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  • 2005-2009  (58)
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  • 1
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    Vickrey Auctions for Railway Tracks (2008)
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    Publication Date: 2020-08-05
    Description: We consider an auction of slots to run trains through a railway network. In contrast to the classical setting for combinatorial auctions, there is not only competition for slots, but slots can mutually exclude each other, such that general conflict constraints on bids arise. This turns the winner determination problem associated with such an auction into a complex combinatorial optimization problem. It also raises a number of auction design questions, in particular, on incentive compatibilty. We propose a single-shot second price auction for railway slots, the Vickrey Track Auction (VTA). We show that this auction is incentive compatible, i.e., rational bidders are always motivated to bid their true valuation, and that it produces efficient allocations, even in the presence of constraints on allocations. These properties are, however, lost when rules on the submission of bids such as, e.g., lowest bids, are imposed. Our results carry over to generalized" Vickrey auctions with combinatorial constraints.
    Keywords: ddc:000
    Language: English
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  • 2
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    Balancing Efficiency and Robustness – A Bi-criteria Optimization Approach to Railway Track Allocation (2008)
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    Publication Date: 2020-08-05
    Description: Technical restrictions and challenging details let railway traffic become one of the most complex transportation systems. Routing trains in a conflict-free way through a track network is one of the basic scheduling problems for any railway company. This article focuses on a robust extension of this problem, also known as train timetabling problem (TTP), which consists in finding a schedule, a conflict free set of train routes, of maximum value for a given railway network. However, timetables are not only required to be profitable. Railway companies are also interested in reliable and robust solutions. Intuitively, we expect a more robust track allocation to be one where disruptions arising from delays are less likely to be propagated causing delays of subsequent trains. This trade-off between an efficient use of railway infrastructure and the prospects of recovery leads us to a bi-criteria optimization approach. On the one hand we want to maximize the profit of a schedule, that is more or less to maximize the number of feasible routed trains. On the other hand if two trains are scheduled as tight as possible after each other it is clear that a delay of the first one always affects the subsequent train. We present extensions of the integer programming formulation in [BorndoerferSchlechte2007] for solving (TTP). These models can incorporate both aspects, because of the additional track configuration variables. We discuss how these variables can directly be used to measure a certain type of robustness of a timetable. For these models which can be solved by column generation techniques, we propose so-called scalarization techniques, see [Ehrgott2005], to determine efficient solutions. Here, an efficient solution is one which does not allow any improvement in profit and robustness at the same time. We prove that the LP-relaxation of the (TTP) including an additional $\epsilon$-constraint remains solvable in polynomial time. Finally, we present some preliminary results on macroscopic real-world data of a part of the German long distance railway network.
    Keywords: ddc:000
    Language: English
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  • 3
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    Simulations of QCD in the Era of Sustained Tflop/s Computing (2008)
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    Publication Date: 2016-06-30
    Description: The latest machine generation installed at supercomputer centres in Germany offers a peak performance in the tens of Tflop/s range. We study performance and scaling of our quantum chromodynamics simulation programme BQCD that we obtained on two of these machines, an IBM Blue Gene/L and an SGI Altix 4700. We compare the performance of Fortran/MPI code with assembler code. The latter allows to exploit concurrency at more levels, in particular in overlapping communication and computation as well as prefetching data from main memory.
    Keywords: ddc:000
    Language: English
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  • 4
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    The minimization of an L^{\infty}-functional subject to an elliptic PDE and state constraints (2008)
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    Publication Date: 2016-06-09
    Description: We study the optimal control of a maximum-norm objective functional subject to an elliptic-type PDE and pointwise state constraints. The problem is transformed into a problem where the non-differentiable L^{\infty}-norm in the functional will be replaced by a scalar variable and additional state constraints. This problem is solved by barrier methods. We will show the existence and convergence of the central path for a class of barrier functions. Numerical experiments complete the presentation.
    Keywords: ddc:000
    Language: English
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  • 5
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    Mehr Mathematik wagen in der Medizin (2008)
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    Publication Date: 2020-11-16
    Description: Der Artikel gibt einen Einblick in das reiche Feld der Zusammenarbeit zwischen Mathematik und Medizin. Beispielhaft werden drei Erfolgsmodelle dargestellt: Medizinische Bildgebung, mathematische Modellierung und Biosignalverarbeitung im Bereich der Dynamik des Herzens sowie mathematische Modellierung und Simulation in der Krebstherapie Hyperthermie und der Mund-Kiefer-Gesichts-Chirurgie. In allen Fällen existiert ein Gleichklang der Interessen von Medizin und Mathematik: Beide Disziplinen wollen die Resultate schnell und zuverlässig. Für die Klinik heißt das, dass notwendige Rechnungen in möglichst kurzer Zeit, und zwar auf dem PC, ablaufen müssen und dass die Resultate so genau und belastbar sein müssen, dass medizinische Entscheidungen darauf aufbauen können. Für die Mathematik folgt daraus, dass höchste Anforderungen an die Effizienz der verwendeten Algorithmen und die darauf aufbauende Software in Numerik und Visualisierung zu stellen sind. Jedes Kapitel endet mit einer Darstellung der Perspektive des jeweiligen Gebietes. Abschließend werden mögliche Handlungsoptionen für Politik und Wirtschaft diskutiert.
    Keywords: ddc:000
    Language: German
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  • 6
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    Constraint Integer Programming: Techniques and Applications (2008)
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    Publication Date: 2022-03-14
    Description: This article introduces constraint integer programming (CIP), which is a novel way to combine constraint programming (CP) and mixed integer programming (MIP) methodologies. CIP is a generalization of MIP that supports the notion of general constraints as in CP. This approach is supported by the CIP framework SCIP, which also integrates techniques for solving satisfiability problems. SCIP is available in source code and free for noncommercial use. We demonstrate the usefulness of CIP on three tasks. First, we apply the constraint integer programming approach to pure mixed integer programs. Computational experiments show that SCIP is almost competitive to current state-of-the-art commercial MIP solvers. Second, we demonstrate how to use CIP techniques to compute the number of optimal solutions of integer programs. Third, we employ the CIP framework to solve chip design verification problems, which involve some highly nonlinear constraint types that are very hard to handle by pure MIP solvers. The CIP approach is very effective here: it can apply the full sophisticated MIP machinery to the linear part of the problem, while dealing with the nonlinear constraints by employing constraint programming techniques.
    Keywords: ddc:000
    Language: English
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  • 7
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    Weiterentwicklung und Ausbau des Internet-Informationsdienstes "Math&Industry" (2008)
    Details
    Publication Date: 2022-04-11
    Description: Mit dem Informationsdienst Math&Industry soll ein Prototyp eines dezentralen Informationssystems für Förderprogramme und Forschungsprojekte geschaffen werden, das sich auf andere Programme (bezüglich angewandter Mathematik, aber auch darüber hinaus) übertragen lässt. Das betrifft sowohl die Konzeption (Strukturierung der Informationen) als auch die Werkzeuge, die anderen BMBF-Förderprogrammen zur Verfügung gestellt werden können. Damit sollen diese in die Lage versetzt werden, die in Math&Industry entwickelten Konzepte und Werkzeuge an ihre spezifischen Bedürfnisse anzupassen.
    Keywords: ddc:000
    Language: German
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  • 8
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    Jahresbericht 2005 (2006)
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    Publication Date: 2019-10-24
    Keywords: ddc:000
    Language: German
    Type: annualzib , doc-type:report
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  • 9
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    Convergence of the Control Reduced Interior Point Method for PDE Constrained Optimal Control with State Constraints (2006)
    Details
    Publication Date: 2014-02-26
    Description: We propose a variant of the control reduced interior point method for the solution of state constrained problems. We show convergence of the corresponding interior point pathfollowing algorithm in function space. Morever, we provide error bounds for the iterates.
    Keywords: ddc:000
    Language: English
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  • 10
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    A Complex Mathematical Model of the Human Menstrual Cycle (2006)
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    Publication Date: 2014-02-26
    Description: This paper aims at presenting the complex coupled network of the human menstrual cycle to the interested community. Beyond the presently popular smaller models, where important network components arise only as extremely simplified source terms, we add: the GnRH pulse generator in the hypothalamus, receptor binding, and the biosynthesis in the ovaries. Simulation and parameter identification are left to a forthcoming paper.
    Keywords: ddc:000
    Language: English
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  • 11
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    A continuity result for Nemyckii Operators and some applications in PDE constrained optimal control (2006)
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    Publication Date: 2014-02-26
    Description: This work explores two applications of a classical result on the continuity of Nemyckii operators to optimal control with PDEs. First, we present an alternative approach to the analysis of Newton's method for function space problems involving semi-smooth Nemyckii operators. A concise proof for superlinear convergence is presented, and sharpened bounds on the rate of convergence are derived. Second, we derive second order sufficient conditions for problems, where the underlying PDE has poor regularity properties. We point out that the analytical structure in both topics is essentially the same.
    Keywords: ddc:000
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  • 12
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    Nash Equilibria in Online Sequential Routing Games (2006)
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    Publication Date: 2014-02-26
    Description: In this paper, we study the efficiency of Nash equilibria for a sequence of nonatomic routing games. We assume that the games are played consecutively in time in an online fashion: by the time of playing game $i$, future games $i+1,\dots,n$ are not known, and, once players of game $i$ are in equilibrium, their corresponding strategies and costs remain fixed. Given a sequence of games, the cost for the sequence of Nash equilibria is defined as the sum of the cost of each game. We analyze the efficiency of a sequence of Nash equilibria in terms of competitive analysis arising in the online optimization field. Our main result states that the online algorithm $\sl {SeqNash}$ consisting of the sequence of Nash equilibria is $\frac{4n}{2+n}$-competitive for affine linear latency functions. For $n=1$, this result contains the bound on the price of anarchy of $\frac{4}{3}$ for affine linear latency functions of Roughgarden and Tardos [2002] as a special case. Furthermore, we analyze a problem variant with a modified cost function that reflects the total congestion cost, when all games have been played. In this case, we prove an upper bound of $\frac{4n}{2+n}$ on the competitive ratio of $\sl {SeqNash}$. We further prove a lower bound of $\frac{3n-2}{n}$ of $\sl {SeqNash}$ showing that for $n=2$ our upper bound is tight.
    Keywords: ddc:000
    Language: English
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  • 13
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    Adaptive, Fast and Oblivious Convolution in Evolution Equations with Memory (2006)
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    Publication Date: 2016-06-09
    Description: To approximate convolutions which occur in evolution equations with memory terms, a variable-stepsize algorithm is presented for which advancing $N$ steps requires only $O(N\log N)$ operations and $O(\log N)$ active memory, in place of $O(N^2)$ operations and $O(N)$ memory for a direct implementation. A basic feature of the fast algorithm is the reduction, via contour integral representations, to differential equations which are solved numerically with adaptive step sizes. Rather than the kernel itself, its Laplace transform is used in the algorithm. The algorithm is illustrated on three examples: a blow-up example originating from a Schrödinger equation with concentrated nonlinearity, chemical reactions with inhibited diffusion, and viscoelasticity with a fractional order constitutive law.
    Keywords: ddc:000
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  • 14
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    Two-layer Network Design by Branch-and-Cut featuring MIP-based Heuristics (2006)
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    Publication Date: 2020-11-13
    Description: This paper deals with MIP-based primal heuristics to be used within a branch-and-cut approach for solving multi-layer telecommunication network design problems. Based on a mixed-integer programming formulation for two network layers, we present three heuristics for solving important subproblems, two of which solve a sub-MIP. On multi-layer planning instances with many parallel logical links, we show the effectiveness of our heuristics in finding good solutions early in the branch-and-cut search tree.
    Keywords: ddc:000
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  • 15
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    Adaptive Finite Element Simulation of Ventricular Fibrillation Dynamics (2006)
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    Publication Date: 2019-05-10
    Description: The dynamics of ventricular fibrillation caused by irregular excitation is simulated in the frame of the monodomain model with an action potential model due to Aliev-Panfilov for a human 3D geometry. The numerical solution of this multiscale reaction-diffusion problem is attacked by algorithms which are fully adaptive in both space and time (code library {\sc Kardos}). The obtained results clearly demonstrate an accurate resolution of the cardiac potential during the excitation and the plateau phases (in the regular cycle) as well as after a reentrant excitation (in the irregular cycle).
    Keywords: ddc:000
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  • 16
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    Orbitopal Fixing (2006)
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    Publication Date: 2020-12-15
    Description: The topic of this paper are integer programming models in which a subset of 0/1-variables encode a partitioning of a set of objects into disjoint subsets. Such models can be surprisingly hard to solve by branch-and-cut algorithms if the permutation of the subsets of the partition is irrelevant. This kind of symmetry unnecessarily blows up the branch-and-cut tree. We present a general tool, called orbitopal fixing, for enhancing the capabilities of branch-and-cut algorithms in solving this kind of symmetric integer programming models. We devise a linear time algorithm that, applied at each node of the branch-and-cut tree, removes redundant parts of the tree produced by the above mentioned permutations. The method relies on certain polyhedra, called orbitopes, which have been investigated in (Kaibel and Pfetsch (2006)). However, it does not add inequalities to the model, and thus, it does not increase the difficulty of solving the linear programming relaxations. We demonstrate the computational power of orbitopal fixing at the example of a graph partitioning problem motivated from frequency planning in mobile telecommunication networks.
    Keywords: ddc:000
    Language: English
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  • 17
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    Approximability of Unsplittable Shortest Path Routing Problems (2006)
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    Publication Date: 2014-11-10
    Description: In this paper, we discuss the relation of unsplittable shortest path routing (USPR) to other routing schemes and study the approximability of three USPR network planning problems. Given a digraph $D=(V,A)$ and a set $K$ of directed commodities, an USPR is a set of flow paths $\Phi_{(s,t)}$, $(s,t)\in K$, such that there exists a metric $\lambda=(\lambda_a)\in \mathbb{Z}^A_+$ with respect to which each $\Phi_{(s,t)}$ is the unique shortest $(s,t)$-path. In the \textsc{Min-Con-USPR} problem, we seek for an USPR that minimizes the maximum congestion over all arcs. We show that this problem is hard to approximate within a factor of $\mathcal{O}(|V|^{1-\epsilon})$, but easily approximable within min$(|A|,|K|)$ in general and within $\mathcal{O}(1)$ if the underlying graph is an undirected cycle or a bidirected ring. We also construct examples where the minimum congestion that can be obtained by USPR is a factor of $\Omega(|V|^2)$ larger than that achievable by unsplittable flow routing or by shortest multi-path routing, and a factor of $\Omega(|V|)$ larger than by unsplittable source-invariant routing. In the CAP-USPR problem, we seek for a minimum cost installation of integer arc capacities that admit an USPR of the given commodities. We prove that this problem is $\mathcal{NP}$-hard to approximate within $2-\epsilon$ (even in the undirected case), and we devise approximation algorithms for various special cases. The fixed charge network design problem \textsc{Cap-USPR}, where the task is to find a minimum cost subgraph of $D$ whose fixed arc capacities admit an USPR of the commodities, is shown to be $\mathcal{NPO}$-complete. All three problems are of great practical interest in the planning of telecommunication networks that are based on shortest path routing protocols. Our results indicate that they are harder than the corresponding unsplittable flow or shortest multi-path routing problems.
    Keywords: ddc:000
    Language: English
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  • 18
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    Availability and Cost Based Evaluation of Demand-wise Shared Protection (2006)
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    Publication Date: 2014-11-11
    Description: In this paper, we investigate the connection availabilities for the new protection scheme Demand-wise Shared Protection (DSP) and describe an appropriate approach for their computation. The exemplary case study on two realistic network scenarios shows that in most cases the availabilities for DSP are comparable with that for 1+1 path protection and better than in case of shared path protection.
    Keywords: ddc:000
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  • 19
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    THESEUS - Protein Structure Prediction at ZIB (2006)
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    Publication Date: 2016-06-30
    Description: THESEUS, the ZIB threading environment, is a parallel implementation of a protein threading based on a multi-queued branch-and-bound optimal search algorithm to find the best sequence-to-structure alignment through a library of template structures. THESEUS uses a template core model based on secondary structure definition and a scoring function based on knowledge-based potentials reflecting pairwise interactions and the chemical environment, as well as pseudo energies for homology detection, loop alignment, and secondary structure matching. The threading core is implemented in C++ as a SPMD parallization architecture using MPI for communication. The environment is designed for generic testing of different scoring functions, e.g. different secondary structure prediction terms, different scoring matrices and information derived from multiple sequence alignments. A validaton of the structure prediction results has been done on the basis of standard threading benchmark sets. THESEUS successfully participated in the 6th Critical Assessment of Techniques for Protein Structure Prediction (CASP) 2004.
    Keywords: ddc:000
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  • 20
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    On the stability of the multi-queue multi-server processor sharing with limited service (2006)
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    Publication Date: 2014-02-26
    Description: We consider a multi-queue multi-server system with $n$ servers (processors) and $m$ queues. At the system there arrives a stationary and ergodic stream of $m$ different types of requests with service requirements which are served according to the following $k$-limited head of the line processor sharing discipline: The first $k$ requests at the head of the $m$ queues are served in processor sharing by the $n$ processors, where each request may receive at most the capacity of one processor. By means of sample path analysis and Loynes' monotonicity method, a stationary and ergodic state process is constructed, and a necessary as well as a sufficient condition for the stability of the $m$ separate queues are given, which are tight within the class of all stationary ergodic inputs. These conditions lead to tight necessary and sufficient conditions for the whole system, also in case of permanent customers, generalizing an earlier result by the authors for the case of $n$=$k$=1.
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  • 21
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    ConfJump : a fast biomolecular sampling method which drills tunnels through high mountains (2006)
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    Publication Date: 2014-02-26
    Description: In order to compute the thermodynamic weights of the different metastable conformations of a molecule, we want to approximate the molecule's Boltzmann distribution in a reasonable time. This is an essential issue in computational drug design. The energy landscape of active biomolecules is generally very rough with a lot of high barriers and low regions. Many of the algorithms that perform such samplings (e.g. the hybrid Monte Carlo method) have difficulties with such landscapes. They are trapped in low-energy regions for a very long time and cannot overcome high barriers. Moving from one low-energy region to another is a very rare event. For these reasons, the distribution of the generated sampling points converges very slowly against the thermodynamically correct distribution of the molecule. The idea of ConfJump is to use $a~priori$ knowledge of the localization of low-energy regions to enhance the sampling with artificial jumps between these low-energy regions. The artificial jumps are combined with the hybrid Monte Carlo method. This allows the computation of some dynamical properties of the molecule. In ConfJump, the detailed balance condition is satisfied and the mathematically correct molecular distribution is sampled.
    Keywords: ddc:000
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  • 22
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    Mathematik für den Volkssport (2006)
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    Publication Date: 2020-02-11
    Description: "`Volkssport Sudoku"' titelt der Stern in seiner Ausgabe vom 24. Mai2006. In der Tat traut sich derzeit kaum noch eine Zeitung, ohne Sudoku zu erscheinen. Die Begeisterung am Lösen dieser Zahlenrätsel offenbart eine unvermutete Freude am algorithmischen Arbeiten. Mathematisch kann man Sudokus als lineare diophantische Gleichungssysteme mit Nichtnegativitätsbedingungen formulieren. Solche ganzzahligen linearen Programme sind die wichtigsten Modellierungswerkzeuge in zahlreichen Anwendungsgebieten wie z.B. der Optimierung von Telekommunikations- und Verkehrsnetzen. Moderne Verfahren zur Lösung dieser Optimierungsprobleme sind durch Sudokus allerdings deutlich weniger zu beeindrucken als Zeitungsleser.
    Keywords: ddc:000
    Language: German
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  • 23
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    Mathematical Methods for Physical Layout of Printed Circuit Boards: An Overview (2006)
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    Publication Date: 2020-02-11
    Description: This article surveys mathematical models and methods used for physical PCB layout, i.e., component placement and wire routing. The main concepts are briefly described together with relevant references.
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  • 24
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    Competitive Online Multicommodity Routing (2006)
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    Publication Date: 2020-12-15
    Description: We study online multicommodity minimum cost routing problems in networks, where commodities have to be routed sequentially. Arcs are equipped with load dependent price functions defining the routing weights. We discuss an online algorithm that routes each commodity by minimizing a convex cost function that depends on the demands that are previously routed. We present a competitive analysis of this algorithm showing that for affine linear price functions this algorithm is $4K/2+K$-competitive, where $K$ is the number of commodities. For the parallel arc case this algorithm is optimal. Without restrictions on the price functions and network, no algorithm is competitive. Finally, we investigate a variant in which the demands have to be routed unsplittably.
    Keywords: ddc:000
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  • 25
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    The extreme points of QSTAB(G) and its implications (2006)
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    Publication Date: 2021-03-16
    Description: Perfect graphs constitute a well-studied graph class with a rich structure, reflected by many characterizations w.r.t different concepts. Perfect graphs are, e.g., characterized as precisely those graphs $G$ where the stable set polytope STAB$(G)$ coincides with the clique constraint stable set polytope QSTAB$(G)$. For all imperfect graphs STAB$(G) \subset$ QSTAB$(G)$ holds and, therefore, it is natural to measure imperfection in terms of the difference between STAB$(G)$ and QSTAB$(G)$. Several concepts have been developed in this direction, for instance the dilation ratio of STAB$(G)$ and QSTAB$(G)$ which is equivalent to the imperfection ratio imp$(G)$ of $G$. To determine imp$(G)$, both knowledge on the facets of STAB$(G)$ and the extreme points of QSTAB$(G)$ is required. The anti-blocking theory of polyhedra yields all {\em dominating} extreme points of QSTAB$(G)$, provided a complete description of the facets of STAB$(\overline G)$ is known. As this is typically not the case, we extend the result on anti-blocking polyhedra to a {\em complete} characterization of the extreme points of QSTAB$(G)$ by establishing a 1-1 correspondence to the facet-defining subgraphs of $\overline G$. We discuss several consequences, in particular, we give alternative proofs of several famous results.
    Keywords: ddc:000
    Language: English
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    On exact algorithms for treewidth (2006)
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    Publication Date: 2014-11-10
    Description: We give experimental and theoretical results on the problem of computing the treewidth of a graph by exact exponential time algorithms using exponential space or using only polynomial space. We first report on an implementation of a dynamic programming algorithm for computing the treewidth of a graph with running time $O^\ast(2^n)$. This algorithm is based on the old dynamic programming method introduced by Held and Karp for the {\sc Tra veling Salesman} problem. We use some optimizations that do not affect the worst case running time but improve on the running time on actual instances and can be seen to be practical for small instances. However, our experiments show that the space use d by the algorithm is an important factor to what input sizes the algorithm is effective. For this purpose, we settle the problem of computing treewidth under the restriction that the space used is only polynomial. In this direction we give a simple $O^\ast(4^n)$ al gorithm that requires {\em polynomial} space. We also show that with a more complicated algorithm, using balanced separators, {\sc Treewidth} can be computed in $O^\ast(2.9512^n)$ time and polynomial space.
    Keywords: ddc:000
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    Coarse Grained Molecular Kinetics (2006)
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    Publication Date: 2014-03-10
    Description: The dynamic behavior of molecules can often be described by Markov processes. From computational molecular simulations one can derive transition rates or transition probabilities between subsets of the discretized conformational space. On the basis of this dynamic information, the spatial subsets are combined into a small number of so-called metastable molecular conformations. This is done by clustering methods like the Robust Perron Cluster Analysis (PCCA+). Up to now it is an open question how this coarse graining in space can be transformed to a coarse graining of the Markov chain while preserving the essential dynamic information. In the following article we aim at a consistent coarse graining of transition probabilities or rates on the basis of metastable conformations such that important physical and mathematical relations are preserved. This approach is new because PCCA+ computes molecular conformations as linear combinations of the dominant eigenvectors of the transition matrix which does not hold for other clustering methods.
    Keywords: ddc:000
    Language: English
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    RSWK/SWD und Faceted Browsing: neue Möglichkeiten einer inhaltlich-intuitiven Navigation (2006)
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    Publication Date: 2014-02-26
    Description: Das deutschsprachige Bibliothekswesen verfügt mit den \glqq Regeln für den Schlagwortkatalog \grqq (RSWK) unter Verwendung der \glqq Schlagwortnormdatei \grqq (SWD) über ein Instrumentarium, welches zusammen mit einem \glqq Faceted Browsing \grqq das bisher bestehende Angebot für ein Information Retrieval optimal ergänzen kann. Die Verbindung zwischen Standardvokabular (SWD) und Kettenbildung (RSWK) einerseits und eine nach Facetten-Eigenschaften gegliederte Navigation andererseits unterstützt bestmöglich eine inhaltlich bezogene Recherche. Die Stärken und Schwächen der RSWK/SWD werden erörtert und auch Klassifikationen (DDC und RVK) als mögliche Facetten diskutiert.
    Keywords: ddc:000
    Language: German
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    Accuracy, Stability, Convergence of Rigorous Thermodynamic Sampling Methods (2006)
    Details
    Publication Date: 2016-06-09
    Keywords: ddc:000
    Language: English
    Type: masterthesis , doc-type:masterThesis
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    Primal Heuristics for Mixed Integer Programs (2006)
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    Publication Date: 2022-03-14
    Description: A lot of problems arising in Combinatorial Optimization and Operations Research can be formulated as Mixed Integer Programs (MIP). Although MIP-solving is an NP-hard optimization problem, many practically relevant instances can be solved in reasonable time. In modern MIP-solvers like the branch-cut-and-price-framework SCIP, primal heuristics play a major role in finding and improving feasible solutions at the early steps of the solution process. This helps to reduce the overall computational effort, guides the remaining search process, and proves the feasibility of the MIP model. Furthermore, a heuristic solution with a small gap to optimality often is sufficient in practice. We investigate 16 different heuristics, all of which are available in SCIP. Four of them arise from the literature of the last decade, nine are specific implementations of general heuristic ideas, three have been newly developed. We present an improved version of the feasibility pump heuristic by Fischetti et al., which in experiments produced solutions with only a third of the optimality gap compared to the original version. Furthermore, we introduce two new Large Neighborhood Search (LNS) heuristics. Crossover is an LNS improvement heuristic making use of similarities of diverse MIP solutions to generate new incumbent solutions. RENS is an LNS rounding heuristic which evaluates the space of all possible roundings of a fractional LP-solution. This heuristic makes it possible to determine whether a point can be rounded to an integer solution and which is the best possible rounding. We conclude with a computational comparison of all described heuristics. It points out that a single heuristic on its own has only a slight impact on the overall performance of SCIP, but the combination of all of them reduces the running time by a factor of two compared to a version without any heuristics.
    Keywords: ddc:000
    Language: English
    Type: masterthesis , doc-type:masterThesis
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    A cartesian grid finite volume method for the solution of the Poisson equation with variable coefficients and embedded interfaces (2006)
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    Publication Date: 2014-02-26
    Description: We present a finite volume method for the solution of the two-dimensional Poisson equation $ \nabla\cdot( \beta( {\mbox{\boldmath $x$}}) \nabla u({\mbox{\boldmath $x$}})) = f(\mbox{\boldmath $x$}) $ with variable, discontinuous coefficients and solution discontinuities on irregular domains. The method uses bilinear ansatz functions on Cartesian grids for the solution $u({\mbox{\boldmath $x$})$ resulting in a compact nine-point stencil. The resulting linear problem has been solved with a standard multigrid solver. Singularities associated with vanishing partial volumes of intersected grid cells or the dual bilinear ansatz itself are removed by a two-step asymptotic approach. The method achieves second order of accuracy in the $L^\infty$ and $L^2$ norm.
    Keywords: ddc:000
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    Efficient Sampling of the Stationary Distribution of Metastable Dynamical Systems (2006)
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    Publication Date: 2014-11-11
    Description: In this article we aim at an efficient sampling of the stationary distribution of dynamical systems in the presence of metastabilities. In the past decade many sophisticated algorithms have been inven ted in this field. We do not want to simply add a further one. We address the problem that one has applied a sampling algorithm for a dynamical system many times. This leads to different samplings which more or less represent the stationary distribution partially very well, but which are still far away from ergodicity or from the global stationary distribution. We will show how these samplings can be joined together in order to get one global sampling of the stationary distribution.
    Keywords: ddc:000
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    Polynomial-Time Algorithms for Linear and Convex Optimization on Jump Systems (2006)
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    Publication Date: 2014-02-26
    Description: The concept of jump system, introduced by Buchet and Cunningham (1995), is a set of integer points with a certain exchange property. In this paper, we discuss several linear and convex optimization problems on jump systems and show that these problems can be solved in polynomial time under the assumption that a membership oracle for a jump system is available. We firstly present a polynomial-time implementation of the greedy algorithm for the minimization of a linear function. We then consider the minimization of a separable-convex function on a jump system, and propose the first polynomial-time algorithm for this problem. The algorithm is based on the domain reduction approach developed in Shioura (1998). We finally consider the concept of M-convex functions on constant-parity jump systems which has been recently proposed by Murota (2006). It is shown that the minimization of an M-convex function can be solved in polynomial time by the domain reduction approach.
    Keywords: ddc:000
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    Packing and Partitioning Orbitopes (2006)
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    Publication Date: 2020-12-15
    Description: We introduce orbitopes as the convex hulls of 0/1-matrices that are lexicographically maximal subject to a group acting on the columns. Special cases are packing and partitioning orbitopes, which arise from restrictions to matrices with at most or exactly one 1-entry in each row, respectively. The goal of investigating these polytopes is to gain insight into ways of breaking certain symmetries in integer programs by adding constraints, e.g., for a well-known formulation of the graph coloring problem. We provide a thorough polyhedral investigation of packing and partitioning orbitopes for the cases in which the group acting on the columns is the cyclic group or the symmetric group. Our main results are complete linear inequality descriptions of these polytopes by facet-defining inequalities. For the cyclic group case, the descriptions turn out to be totally unimodular, while for the symmetric group case, both the description and the proof are more involved. The associated separation problems can be solved in linear time.
    Keywords: ddc:000
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    LP-Based Local Approximation for Markov Decision Problems (2006)
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    Publication Date: 2014-11-21
    Description: The standard computational methods for computing the optimal value functions of Markov Decision Problems (MDP) require the exploration of the entire state space. This is practically infeasible for applications with huge numbers of states as they arise, e.\,g., from modeling the decisions in online optimization problems by MDPs. Exploiting column generation techniques, we propose and apply an LP-based method to determine an $\varepsilon$-approximation of the optimal value function at a given state by inspecting only states in a small neighborhood. In the context of online optimization problems, we use these methods in order to evaluate the quality of concrete policies with respect to given initial states. Moreover, the tools can also be used to obtain evidence of the impact of single decisions. This way, they can be utilized in the design of policies.
    Keywords: ddc:000
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    Ein gemischt-ganzzahliges lineares Optimierungsmodell für ein Laserschweißproblem im Karosseriebau (2006)
    Details
    Publication Date: 2014-11-21
    Description: Wir beschäftigen uns mit dem Problem der Betriebsplanung von Laserschweißrobotern im Karosseriebau. Gegeben ist eine Menge von Schweißnähten, die innerhalb einer Fertigungszelle an einem Karosserieteil gefertigt werden müssen. Die Schweißnähte werden durch mehrere parallel betriebene Roboter bearbeitet. Die Aufgabe besteht darin, für jeden Roboter eine Reihenfolge und eine zeitliche Koordinierung seiner Bewegungen zu finden, so dass alle Schweißnähte innerhalb der Taktzeit der Fertigungszelle bearbeitet werden und so wenig Laserquellen wie möglich eingesetzt werden. Dabei müssen einige Nebenbedingungen berücksichtigt werden. Für dieses spezielle Schweißproblem haben wir eine Formulierung als gemischt-ganzzahliges lineares Programm entwickelt, welches sich für die untersuchten praktischen Fälle sehr schnell lösen lässt.
    Keywords: ddc:000
    Language: German
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    Software for Teaching Modeling of Integer Programming Problems (2006)
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    Publication Date: 2021-08-05
    Description: Modern applications of mathematical programming must take into account a multitude of technical details, business demands, and legal requirements. Teaching the mathematical modeling of such issues and their interrelations requires real-world examples that are well beyond the toy sizes that can be tackled with the student editions of most commercial software packages. We present a new tool, which is freely available for academic use including complete source code. It consists of an algebraic modeling language and a linear mixed integer programming solver. The performance and features of the tool are in the range of current state-of-the-art commercial tools, though not in all aspects as good as the best ones. Our tool does allow the execution and analysis of large real-world instances in the classroom and can therefore enhance the teaching of problem solving issues. Teaching experience has been gathered and practical usability was tested in classes at several universities and a two week intensive block course at TU Berlin. The feedback from students and teachers has been very positive.
    Keywords: ddc:000
    Language: English
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    On the Bottleneck Shortest Path Problem (2006)
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    Publication Date: 2014-11-21
    Description: The Bottleneck Shortest Path Problem is a basic problem in network optimization. The goal is to determine the limiting capacity of any path between two specified vertices of the network. This is equivalent to determining the unsplittable maximum flow between the two vertices. In this note we analyze the complexity of the problem, its relation to the Shortest Path Problem, and the impact of the underlying machine/computation model.
    Keywords: ddc:000
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  • 39
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    Graph Coloring Manifolds (2006)
    Details
    Publication Date: 2014-02-26
    Description: We introduce a new and rich class of graph coloring manifolds via the Hom complex construction of Lov\´{a}sz. The class comprises examples of Stiefel manifolds, series of spheres and products of spheres, cubical surfaces, as well as examples of Seifert manifolds. Asymptotically, graph coloring manifolds provide examples of highly connected, highly symmetric manifolds.
    Keywords: ddc:000
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  • 40
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    Polyhedra of Genus 3 with 10 Vertices and Minimal Coordinates (2006)
    Details
    Publication Date: 2014-02-26
    Description: We give coordinate-minimal geometric realizations in general position for 17 of the 20 vertex-minimal triangulations of the orientable surface of genus 3 in the 5x5x5-cube.
    Keywords: ddc:000
    Language: English
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    ConFlow? A new space-based Application for complete Conformational Analysis of Molecules (2006)
    Details
    Publication Date: 2014-02-26
    Description: Biochemical interactions are determined by the 3D-structure of the involved components - thus the identification of conformations is a key for many applications in rational drug design. {\sf ConFlow} is a new multilevel approach to conformational analysis with main focus on completeness in investigation of conformational space. In contrast to known conformational analysis, the starting point for design is a space-based description of conformational areas. A tight integration of sampling and analysis leads to an identification of conformational areas simultaneously during sampling. An incremental decomposition of high-dimensional conformational space is used to guide the analysis. A new concept for the description of conformations and their path connected components based on convex hulls and {\em Hypercubes}is developed. The first results of the {\sf ConFlow} application constitute a 'proof of concept' and are further more highly encouraging. In comparison to conventional industrial applications, {\sf ConFlow} achieves higher accuracy and a specified degree of completeness with comparable effort.
    Keywords: ddc:000
    Language: English
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  • 42
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    Iteratively Solving Linear Inverse Problems under General Convex Contraints (2006)
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    Publication Date: 2014-02-26
    Description: We consider linear inverse problems where the solution is assumed to fulfill some general homogeneous convex constraint. We develop an algorithm that amounts to a projected Landweber iteration and that provides and iterative approach to the solution of this inverse problem. For relatively moderate assumptions on the constraint we can always prove weak convergence of the iterative scheme. In certain cases, i.e. for special families of convex constraints, weak convergence implies norm convergence. The presented approach covers a wide range of problems, e.g. Besov- or BV-restoration for which we present also numerical experiments in the context of image processing.
    Keywords: ddc:000
    Language: English
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    Stable computation of probability densities for metastable dynamical systems (2006)
    Details
    Publication Date: 2014-03-10
    Description: Whenever the invariant stationary density of metastable dynamical systems decomposes into almost invariant partial densities, its computation as eigenvector of some transition probability matrix is an ill-conditioned problem. In order to avoid this computational difficulty, we suggest to apply an aggregation/disaggregation method which only addresses wellconditioned sub-problems and thus results in a stable algorithm. In contrast to existing methods, the aggregation step is done via a sampling algorithm which covers only small patches of the sampling space. Finally, the theoretical analysis is illustrated by two biomolecular examples.
    Keywords: ddc:000
    Language: English
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    Facets of the (s,t)-p-path polytope (2006)
    Details
    Publication Date: 2016-02-29
    Description: \noindent We give a partial description of the $(s,t)-p$-path polytope of a directed graph $D$ which is the convex hull of the incidence vectors of simple directed $(s,t)$-paths in $D$ of length $p$. First, we point out how the $(s,t)-p$-path polytope is located in the family of path and cycle polyhedra. Next, we give some classes of valid inequalities which are very similar to inequalities which are valid for the $p$-cycle polytope, that is, the convex hull of the incidence vectors of simple cycles of length $p$ in $D$. We give necessary and sufficient conditions for these inequalities to be facet defining. Furthermore, we consider a class of inequalities that has been identifie d to be valid for $(s,t)$-paths of cardinality at most $p$. Finally, we transfer the results to related polytopes, in particular, the undirected counterpart of the $(s,t)-p$-path polytope.
    Keywords: ddc:000
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    A Contact-Stabilized Newmark Method for Dynamical Contact Problems (2006)
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    Publication Date: 2020-11-13
    Description: The numerical integration of dynamical contact problems often leads to instabilities at contact boundaries caused by the non-penetration condition between bodies in contact. Even a recent energy dissipative modification due to Kane et al. (1999), which discretizes the non-penetration constraints implicitly, is not able to circumvent artificial oscillations. For this reason, the present paper suggests a contact stabilization which avoids artificial oscillations at contact interfaces and is also energy dissipative. The key idea of this contact stabilization is an additional $L^2$-projection at contact interfaces, which can easily be added to any existing time integration scheme. In case of a lumped mass matrix, this projection can be carried out completely locally, thus creating only negligible additional numerical cost. For the new scheme, an elementary analysis is given, which is confirmed by numerical findings in an illustrative test example (Hertzian two body contact).
    Keywords: ddc:000
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    Implementation eines Resourcebrokers im Kontext eines Grid-Datenmanagement-Systems (2006)
    Details
    Publication Date: 2016-06-30
    Keywords: ddc:000
    Language: German
    Type: masterthesis , doc-type:masterThesis
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    Enumeration and Random Realization of Triangulated Surfaces (2006)
    Details
    Publication Date: 2014-02-26
    Description: We discuss different approaches for the enumeration of triangulated surfaces. In particular, we enumerate all triangulated surfaces with 9 and 10 vertices. We also show how geometric realizations of orientable surfaces with few vertices can be obtained by choosing coordinates randomly.
    Keywords: ddc:000
    Language: English
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    Note on L#-convex Function Minimization Algorithms: Comparison of Murota's and Kolmogorov's Algorithms (2006)
    Details
    Publication Date: 2014-02-26
    Description: The concept of L##-convexity is introduced by Fujishige--Murota (2000) as a discrete convexity for functions defined over the integer lattice. The main aim of this note is to understand the difference of the two algorithms for L##-convex function minimization: Murota's steepest descent algorithm (2003) and Kolmogorov's primal algorithm (2005).
    Keywords: ddc:000
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    Triangulated Manifolds with Few Vertices: Combinatorial Manifolds (2006)
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    Publication Date: 2014-02-26
    Description: In this survey on combinatorial properties of triangulated manifolds we discuss various lower bounds on the number of vertices of simplicial and combinatorial manifolds. Moreover, we give a list of all known examples of vertex-minimal triangulations.
    Keywords: ddc:000
    Language: English
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    Optimizing the Landside Operation of a Container Terminal (2006)
    Details
    Publication Date: 2020-02-11
    Description: This paper concerns the problem of operating a landside container exchange area that is serviced by multiple semi-automated rail mounted gantry cranes (RMGs) that are moving on a single bi-directional traveling lane. Such a facility is being built by Patrick Corporation at the Port Botany terminal in Sydney. The gantry cranes are a scarce resource and handle the bulk of container movements. Thus, they require a sophisticated analysis to achieve near optimal utilization. We present a three stage algorithm to manage the container exchange facility, including the scheduling of cranes, the control of associated short-term container stacking, and the allocation of delivery locations for trucks and other container transporters. The key components of our approach are a time scale decomposition, whereby an integer program controls decisions across a long time horizon to produce a balanced plan that is fed to a series of short time scale online subproblems, and a highly efficient space-time divisioning of short term storage areas. A computational evaluation shows that our heuristic can find effective solutions for the planning problem; on real-world data it yields a solution at most~8\% above a lower bound on optimal RMG utilization.
    Keywords: ddc:000
    Language: English
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    Triangulated Manifolds with Few Vertices: Vertex-Transitive Triangulations I (2006)
    Details
    Publication Date: 2014-02-26
    Description: We describe an algorithm for the enumeration of (candidates of) vertex-transitive combinatorial $d$-manifolds. With an implementation of our algorithm, we determine, up to combinatorial equivalence, all combinatorial manifolds with a vertex-transitive automorphism group on $n\leq 13$ vertices. With the exception of actions of groups of small order, the enumeration is extended to 14 and 15 vertices.
    Keywords: ddc:000
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    Polyhedra of Genus 2 with 10 Vertices and Minimal Coordinates (2006)
    Details
    Publication Date: 2014-02-26
    Description: We give coordinate-minimal geometric realizations in general position of all 865 vertex-minimal triangulations of the orientable surface of genus 2 in the 4x4x4-cube.
    Keywords: ddc:000
    Language: English
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    Combinatorial 3-Manifolds with 10 Vertices (2006)
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    Publication Date: 2014-02-26
    Description: We give a complete enumeration of combinatorial 3-manifolds with 10 vertices: There are precisely 247882 triangulated 3-spheres with 10 vertices as well as 518 vertex-minimal triangulations of the sphere product $S^2 x S^1$ and 615 triangulations of the twisted sphere product $S^2 \underline{x} S^1$. An analysis of the 3-spheres with up to 10 vertices shows that all these spheres are shellable, but that there are 29 vertex-minimal non-shellable 3-balls with 9 vertices.
    Keywords: ddc:000
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    Adaptive Linearly Implicit Methods for Linear Poroelastic Equations (2006)
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    Publication Date: 2019-05-10
    Description: Adaptive numerical methods in time and space are introduced and studied for linear poroelastic models in two and three space dimensions. We present equivalent models for linear poroelasticity and choose both the {\em displacement--pressure} and the {\em stress--pressure} formulation for our computations. Their discretizations are provided by means of linearly implicit schemes in time and linear finite elements in space. Our concept of adaptivity opens a way to a fast and reliable simulation of different loading cases defined by corresponding boundary conditions. We present some examples using our code {\sf Kardos} and show that the method works efficiently. In particular, it could be used in the simulation of some bone healing models.
    Keywords: ddc:000
    Language: English
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    A computational approach to microRNA detection (2006)
    Details
    Publication Date: 2016-06-30
    Description: During the last few years more and more functionalities of RNA have been discovered that were previously thought of being carried out by proteins alone. One of the most striking discoveries was the de tection of microRNAs, a class of noncoding RNAs that play an important role in post-transcriptional gene regulation. Large-scale analyses are needed for the still increasingly growing amount of sequen ce data derived from new experimental technologies. In this paper we present a framework for the detection of the distinctive precursor structure of microRNAS that is based on the well-known Smith-Wat erman algorithm and various filtering steps. We conducted experiments on real genomic data and we found several new putative hits for microRNA precursor structures.
    Keywords: ddc:000
    Language: English
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  • 56
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    Neustart für Bibliotheken ins Informationszeitalter (2006)
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    Publication Date: 2014-02-26
    Description: Wir erleben zu Beginn des aufkommenden Informationszeitalters mit dem Siegeszug von Google und anderen Internet-Technologien einen Wandel im Verhalten von Wissenschaftlern und Studenten, der mit dem Einsatz von {\sl Google Scholar} und {\sl Google Book Search} einen Paradigmenwechsel für Bibliotheken und Informationsversorger gleichkommt. Der Artikel untersucht die technischen Hintergründe für den Erfolg dieser besonderen Art des Information Retrievals: Fulltext Indexing und Citation Ranking als besondere Form des Information Minig. Er diskutiert Stärken und auch Schwächen des Google-Ansatzes. Der Autor stellt sich auch der Frage, unter welchen Bedingungen es möglich ist, ein zu {\sl Google Scholar} und der {\sl Google Book Search} konkurrenzfähiges Retrieval in der Landschaft der Bibliotheken und Bibliotheksverbünde zu entrichten. Die These ist, dass dieses unter Einsatz des {\sl Open Source} Indexierers {\sl Lucene} und des Web-Robots {\sl Nutch} möglich ist. Bibliotheken können durch gezielten Einsatz solcher Internet-Technologien dem Nutzer die Leistungen, welche Google uns mit seinen Tools im {\sl Visible Web} und mit Referenzen auf {\sl Citations} in der Welt der Literatur zur Verfügung stellt, in vergleichbarer Art auch für ihre eigenen durch Lizenzen geschützten digitalen Journale und ihre speziellen lokal verfügbaren Ressourcen, auf die Internet-Suchmaschinen keine Zugriff haben, anbieten. Es besteht die Hoffnung, dass Nutzer dann nicht - wie in einer kürzlichen Studie des OCLC konstatiert - überwiegend im Internet verbleiben, sondern bei ihrer Suche auch den Weg zu den Angeboten der örtlichen Bibliothek attraktiv finden.
    Keywords: ddc:000
    Language: German
    Type: reportzib , doc-type:preprint
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  • 57
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    Waiting times for M/M systems under generalized processor sharing (2006)
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    Publication Date: 2014-02-26
    Description: We consider a system where the arrivals form a Poisson process and the required service times of the requests are exponentially distributed. According to the generalized processor sharing discipline, each request in the system receives a fraction of the capacity of one processor which depends on the actual number of requests in the system. We derive systems of ordinary differential equations for the LST and for the moments of the conditional waiting time of a request with given required service time as well as a stable and fast recursive algorithm for the LST of the second moment of the conditional waiting time, which in particular yields the second moment of the unconditional waiting time. Moreover, asymptotically tight upper bounds for the moments of the conditional waiting time are given. The presented numerical results for the first two moments of the sojourn times in the $M/M/m-PS$ system show that the proposed algorithms work well.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 58
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    Domain Decomposition Method for Maxwell's Equations: Scattering off Periodic Structures (2006)
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    Publication Date: 2022-07-07
    Description: We present a domain decomposition approach for the computation of the electromagnetic field within periodic structures. We use a Schwarz method with transparent boundary conditions at the interfaces of the domains. Transparent boundary conditions are approximated by the perfectly matched layer method (PML). To cope with Wood anomalies appearing in periodic structures an adaptive strategy to determine optimal PML parameters is developed. We focus on the application to typical EUV lithography line masks. Light propagation within the multi-layer stack of the EUV mask is treated analytically. This results in a drastic reduction of the computational costs and allows for the simulation of next generation lithography masks on a standard personal computer.
    Keywords: ddc:000
    Language: English
    Type: reportzib , doc-type:preprint
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  • 59
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    Incremental modification of styrene-butadiene rubber with tert-dodecyl mercaptan (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 116-123 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The molecular weights and molecular weight distribution of a styrene-butadiene rubber produced at 5°C. according to an incrementally modified recipe with tert-dodecyl mercaptan modifier, do not differ significantly from those of similar conventionally modified rubbers. The limiting effect of diffusion upon the mass transfer of mercaptan in the system provides a consistent explanation of this finding.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051318
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  • 60
    Electronic Resource
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    Glass transitions in polymers (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. S1 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051319
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  • 61
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    Polymer news (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. S4 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051321
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  • 62
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    Use of the HLB system in selecting emulsifiers for emulsion polymerization (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 135-148 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the present work a wide variety of nonionic emulsifiers and anionic/nonionic blends of emulsifiers were evaluated in the emulsion polymerization of vinyl acetate and styrene. It was found that the emulsion stability and other polymer emulsion properties are often dependent upon a certain property of the emulsifier known as the HLB value. It has been shown elsewhere that the HLB value can be correlated with a fundamental physical property of the system oil-water-emulsifier, namely, the spreading coefficient of the internal phase liquid on the surface of a 1% solution of the emulsifier in the external phase. In the emulsion polymerization of styrene, good emulsion stability coupled with adequate conversion rate was obtained in an emulsifier HLB range of 13 to 16. For certain emulsifier blends it was found that emulsion viscosity and emulsion particle size were strongly dependent on the HLB of the emulsifier. Similar comments apply to vinyl acetate polymerization, except that the most stable emulsions were obtained with emulsifiers in an HLB range from 14.5 to 17.5. These observations on preferred HLB range apply only to nonionic emulsifiers and anionic/nonionic emulsifier blends, which were the emulsifier types screened in the present investigation. For both styrene and vinyl acetate the most generally satisfactory emulsion properties were obtained in the present work by the use of an anionic/nonionic emulsifier blend (G-3300/G-3920).
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051402
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  • 63
    Electronic Resource
    Electronic Resource
    Influence of the initiator on the grafting of polyvinyl polymers (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 149-152 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dependence of grafting on the type of initiator has been examined in the case of three polymer-monomer systems: polystyrene-methyl methacrylate, polymethyl methacrylate-vinyl acetate, and polyethyl α-chloroacrylate-vinyl acetate. The different initiators used in these experiments were benzoyl peroxide (Bz2O2), azobisisobutyronitrile (AIBN), di-tert-butyl peroxide (DTBP), and tert-butyl hydroperoxide (TBHP). In each case the graft copolymers were separated from the homopolymers by fractional precipitation or by extraction. In the case of the system polystyrene-methyl methacrylate, an appreciable degree of grafting as well as formation of graft copolymer occur in the presence of Bz2O2; in contrast, the grafting is low with DTBP and doubtful with AIBN. For the other two systems no noticeable differences occurred as function of the initiator. In the case of polyethyl α-chloroacrylate the amount of graft copolymer is exceptionally high owing to the sensitivity of this polymer to a radical attack; this sensitivity results in the partial insolubility of the graft copolymers in the presence of TBHP and DTBP, but not in the presence of AIBN.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051403
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  • 64
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    A new synthetic elastomer based on a chlorophosphonated polyolefin (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 157-162 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new synthetic elastomer has been obtained based on an ethylene-propylene copolymer prepared using an organometallic catalyst system. Reactive sites (phosphonyl dichloride groups) are placed on the copolymer chain by treating the polymer with phosphorus trichloride and oxygen. After hydrolysis or alcoholysis of the phosphonyl dichloride groups to phosphonic acid or phosphonic acid esters, vulcanization may be carried out by reaction with metallic oxides, particularly lead oxide. Vulcanizates of the polyolefin elastomer have outstanding resistance to heat, ozone, and oxygen, and have excellent electrical properties. This combination suggests the use of this material in high temperature electrical applications.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051405
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  • 65
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    Changes in fine structure and mechanical properties induced by cyanoethylation of cotton yarns. II. Reacted without longitudinal shrinkagePaper presented before the 138th Meeting of the American Chemical Society, New York, September 11-16, 1960. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 163-170 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The cellulose of cotton yarns was reacted with acrylonitrile under conditions preventing their longitudinal contraction. Changes taking place in the fine structure of the fiber were studied by means of optical microscopy, density measurements, x-ray diffraction, and thermal stress behavior measurements. The results indicate that in spite of the strong tensions developed in the yarns, the reaction proceeds in both the accessible and the crystalline regions with considerable volume expansion and eventual disappearance of crystalline structure. Suggestions of a glass transition temperature appear at substitutions slightly above D.S. = 1. Annealing becomes possible at substitutions above D.S. = 2 with the development of the cyanoethyl cellulose crystal structure and over 40% increase in tensile strength. Changes in tenacity, ultimate elongation, energy of rupture, and immediate elastic recovery were also observed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051406
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  • 66
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    Poly(4-methyl-1-pentene) and some soluble crystalline copolymers (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 184-190 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(4-methyl-1-pentene) has been prepared by polymerizing the monomer over a catalyst made from titanium tetrachloride and lithium aluminum tetradecyl. The molecular weight of the crystalline polymer was invariably too high for fiber preparation, even when polymerization variables were varied drastically, so a technique for thermal cracking was developed. By heating grease-free, crystalline poly(4-methyl-1-pentene) in a vacuum at about 280°, it was possible to lower smoothly the molecular weight of the polymer to any desired value, without undesirable crosslinking or by-product formation. The polymer was melt-spun by conventional techniques to highly oriented, tough fibers. Copolymerization of 10-25% 1-hexene and other linear 1-olefins with 4-methyl-1-pentene gives products which are still high-melting, but which are readily soluble in such solvents as cyclohexane or chloroform, in contrast to the homopolymer which is only slightly soluble. Polymerization in solvents for the copolymer gave solutions which were converted to fibers and film without intermediate isolation of polymer or removal of the catalyst. An interesting terpolymer in which divinylbenzene was the third component was found to be initially soluble, but was readily crosslinked at elevated temperature.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051409
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  • 67
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    Structural characterization of vulcanizates. Part II. Use of triphenylphosphine to determine the structures of sulfur linkages in unaccelerated natural rubber-sulfur vulcanizate networks (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 299-302 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Treatment of unaccelerated natural rubber-sulfur vulcanizate networks with triphenylphosphine in benzene at 80°C. effects the removal of part of the combined sulfur, the proportion removed decreasing with increasing cure time. This partial desulfurization of the network is attributed, on the basis of the mode of interaction of simple organic di- and polysulfides with triphenylphosphine, to the conversion of polysulfide linkages in the network into either mono- or disulfide groups. Knowledge of the amount of sulfur removed by the reagent, and of the chemical degree of crosslinking and combined sulfur content of the untreated networks permits the following semiquantitative conclusions to be reached concerning the structures of the sulfur linkages in the networks: (1) long polysulfidic crosslinks (—S11— to —S12—) are initially formed, which on continued cure progressively decrease in length to a limiting value of —S2— to —S4—; and (2) a very high proportion to the combined sulfur (ca. 77% for short cure times, increasing to ca. 95% on extended cure) is present in cyclic monosulfide groups situated along the polyisoprene chains.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051508
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  • 68
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    The relationship between glass temperature, molar cohesion, and polymer structurePresented before the Division of Polymer Chemistry at the 138th meeting of the American Chemical Society, New York, September 1960. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 318-321 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An empirical equation relating glass temperature, molar cohesion, and polymer structure has been developed from data found in the literature. A fairly extensive list of group cohesion values has been obtained from this relationship and glass temperatures which are in good agreement with reported values have been calculated. The equation is $$ H_c = 0.5nRT_g - 25n $$ where Hc is the molar cohesion and n is an empirical number obtained from the polymer structure.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051511
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  • 69
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    Isobutylene copolymers of vinylbenzyl chloride and isopropenylbenzyl chloride (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 452-459 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The styrene derivatives vinylbenzyl chloride and isopropenylbenzyl chloride were prepared and copolymerized with isobutylene and propylene in order to produce polymers with reactive halogens. Vinylbenzyl chloride and isobutylene have relative reactivities such that the copolymer is much richer in isobutylene than the starting mixture, while with isopropenylbenzyl chloride and isobutylene the difference in reactivities is less and is in the opposite direction. Copolymers containing small amounts of the reactive benzylic chlorine were vulcanized, either with amines or with a conventional butyl rubber cure. Permselective membranes were prepared from copolymers rich in benzylic chlorine.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051611
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  • 70
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    The mechanism of post cure of viton ARegistered trademark of E. I. du Pont de Nemours & Co., Inc. Fluorocarbon elastomerBased on a lecture delivered at the 2nd International Synthetic Rubber Symposium, London, October 1960, by arrangement with Rubber and Plastics World. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 460-467 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The necessity for oven post-curing Viton A vulcanizates is explained in the following way: The formation of crosslinks is accompanied by the elimination of HF from the polymer. In the subsequent reaction of HF with the magnesium oxide present as acid acceptor water is formed which acts to inhibit the full development of cure unless it is removed from the vicinity of the polymer by post-curing in an open system. Measurement of the rate of elimination of water from the polymer serves as a method of following the development of crosslinking during cure. Approximately two moles of water, derived from four moles of hydrogen fluoride, are associated with the use of one mole of diamine curing agent. This ratio is confirmed by independent estimates of the relationship of crosslinking density to curing agent level based on measurements of swollen compression moduli.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051612
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  • 71
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    Room temperature sulfur and nonsulfur vulcanization of natural rubber: With sulfur and piperidinium n-pentamethylenedithiocarbamate and with quinone dioxime (GMF) and yellow mercuric oxide (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 349-353 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Calendered sheets of pale crepe rubber containing an ultra-accelerator, piperidinium N-pentamethylenedithiocarbamate, and zinc oxide were embedded in powdered sulfur and kept at room temperature. Tensile strengths up to 294.2 kg./cm.2 (4185 psi) and elongations up to 530% were attained; the combined sulfur in 115 weeks was 3.60%. Calendered pale crepe rubber containing 10 parts of yellow mercuric oxide to 100 parts of rubber allowed to stand covered with quinone dioxime (GMF) powder at room temperature slowly vulcanizes, reaching a tensile strength of 53.1 kg./cm.2 (754 psi) in 405 days, and retaining this condition for at least twice this same period of time. The elongation reached 740%, and the set was 0.16. The tensile strength obtained is almost as high as that obtained in a press cure with quinone dioxime alone. The untreated sample containing yellow mercuric oxide alone showed a tensile strength of only 5.3 kg./cm.2 (75 psi). Calendered pale crepe with no mercuric oxide set in quinone dioxime and calendered pale crepe containing 2 parts of quinone dioxime, when allowed to stand at room temperature, showed no signs of vulcanization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051515
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  • 72
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    Uniformity of substitution during the emulsion xanthation of celluloseA portion of a thesis submitted in partial fulfillment of the requirements of The Institute of Paper Chemistry for the degree of Doctor of Philosophy from Lawrence College, Appleton, Wis., June, 1960. This work was carried out under the direction of Kyle Ward, Jr. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 364-369 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Viscose-grade cotton linters (DPw = 1135) were converted to viscose by the emulsion xanthation technique. Two variables - namely, substitution level and xanthation time - were considered insofar as their influence on the uniformity of substitution with regard to chain length was concerned. The stable diethylacetamide derivatives were prepared by reaction with diethylchloroacetamide and fractionally precipitated from aqueous 2-chloroethanol. The DPw and degree of substitution (DS) of the individual fractions were determined. The results in each case indicated that the longer chains were more highly substituted than the shorter chains. For a constant xanthation time (6 hr.), uniformity in substitution improved with increasing substitution level. For a constant CS2:cellulose ratio (1.48), uniformity increased with xanthation time. A mechanism is suggested which accounts for these phenomena.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/app.1961.070051517
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  • 73
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    A comparison of the thermal gradient and elution methods of polymer fractionation (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 354-363 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The elution method is essentially a single-stage process, whereas the thermal gradient method is a multistage process which depends upon a thermal gradient to bring about reprecipitation of polymer in the fractions. As a test of the effectiveness of the thermal gradient, comparisons have been made of fractionation by these two column methods on high molecular weight polystyrene samples. It was found that the thermal gradient method definitely provides superior resolution and reproducibility, as expected. However, the degree of fractionation obtained by the elution method was surprising, accounting for at least 80% of the sample under the usual conditions and giving complete fractionation with certain modifications of conditions. These results indicate the difference in performance of the two methods is less than expected from an elementary consideration of the operation of the columns, and fractionation by the elution method, as conducted here, exceeds that expected for a single-stage extraction process. Although the reasons for the observed behavior are not clear, the following conclusions have been reached about certain factors which influence fractionation. Alternative methods of controlling the concentration of polymer in the fractions give almost equivalent results but enhanced resolution of the high molecular weight portion of the sample is obtained with extended solvent gradients. The inhibitor, tert-butyl catechol, which it was necessary to add to the solvents to limit degradation of the very high molecular weight sample, plays a specific role in the fractionation due to a reaction with the polystyrene which alters the fractionation behavior without affecting the molecular weight. Also, trace amounts of chemical heterogeneity in the polymers, presumably hydroxyl groups, have a marked adverse effect on fractionation by the elution method and probably account for molecular weight reversals observed in some fractionations by the thermal gradient method. It is suggested that adsorption on the surface of the beads is responsiblp for the adverse effect of chemical heterogeneity on the fractionation and that possibly an adsorption which increases with molecular weight contributes to fractionation by the elution and thermal gradient methods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051516
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    Effects of by-products, trace components, and similar compounds in viscose on ripening (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 375-383 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects on viscose ripening of a variety of materials are reported. (1) Normal constituents (Na2CO3, Na2CS3, NaCl) appeared not to affect ripening; however, Na2S retarded ripening. By-product removal appeared to retard ripening. (2) Oxidizing agents (H2O2, Na2Sx) accelerated ripening; reducing agent (Na2SO3) retarded ripening; this is suggestive of possible addition product formation. (3) Na2SO4, (CH3)2SO, KClO3, Na2BH4 showed no effect on ripening. (4) Salts which precipitated as hydroxides or carbonates did not appear to affect ripening. (5) Salts which formed insoluble sulfides resulted in an initial increase in ripening rates. In later stages, ripening proceeded normally, probably after the salts were removed from solution as insoluble sulfides. (6) FeCl3, BiCl3 and Na3AsO3 appeared to retard ripening. (7) A comparison of the effect on ripening of the trivalent state of elements in group V of the periodic table showed that the rate of ripening decreased with the oxidation potential of the element. (8) The addition of sodium zincate retarded ripening and suggested possible cross-linking of xanthate and by-product sulfur, or of two xanthate groups. (9) Addition of tin and chromium salts at the 0.5% level resulted in gelation of the viscose within 30 min. after the addition.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051601
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    Radiation crosslinking of vinyl chloride-vinyl stearate copolymer (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 388-396 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The crosslinking of internally plasticized polyvinyl chloride-stearate copolymer by irradiation with high-energy electrons was studied. Based on gel yields and swelling as a measure of relative crosslinking, the effect of added tetra-functional monomers, and of carbon black and silica fillers are discussed. Crosslinking by dicumyl peroxide a t 170°C. even in the presence of a stabilizer, causes concurrent decomposition (dehydrochlorination) which is avoided in the radiation-crosslinking process. The heat stability of the copolymer is not impaired by radiation crosslinking under the proper conditions. Results of tensile measurements a t 25 and 150°C. are given for the radiation-crosslinked copolymer with and without filler reinforcement.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051603
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  • 76
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    Studies on the γ-irradiation of natural rubber latex. The effects of organic halogen compounds on crosslinking by γ-irradiation (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 401-407 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: As the accelerating effect of water in the crosslinking reaction of rubber in natural latex by γ-irradiation was assumed to stem from the decomposition of water into radicals by γ-irradiation, more effective reagents were sought among the organic halides which have greater G values for radical formation by γ-irradiation and, simultaneously, an affinity for rubber greater than that of water. 1,2-Dichloroethane, chloroform, carbon tetrachloride, and benzene (for comparison) were tested, and these compounds, except for benzene, were found to accelerate the reaction in proportion to their G values for radical formation. Benzene was found to have no effect, in concentrations between 1 and 5 phr. The optimum dosage was decreased to 2.1 × 106, 1.0 × 106, and 7.6 × 105 r by the addition of 1, 3, and 5 phr of carbon tetrachloride, respectively, and was assumed to have decreased to 1.17 × 107, 9.0 × 106, and 7.6 × 106 r with 1, 3, and 5 phr of 1,2-dichloroethane, and to 8.6 × 106, 6.2 × 106, and 5.2 × 106 r with 1, 3, and 5 phr of chloroform, respectively. The physical properties of the films obtained at the optimum dosages under these accelerating conditions were equal to those of the latex irradiated up to the optimum dosage with no addition of halide. No side reactions occurred during the halide-accelerated crosslinking that were sufficiently extensive to influence the infrared spectra.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051605
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  • 77
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    The estimation of catalytic parameters of metal acetylacetonates in isocyanate polymerization reactionsContribution No. 202. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 424-427 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The polyaddition process involving a hydroxy-terminated linear polyester and an organic diisocyanate in the presence of a series of metal acetylacetonates has been investigated. The method involved kinetic analysis of plasticity build-up in a Brabender Plastograph. Catalytic orders and relative catalytic constants (kc/k0) were determined for Mn(Aa)3, VO(Aa)2, V(Aa)3, Fe(Aa)3, Cu(Aa)2, Co(Aa)3, and Cr(Aa)3; the constants decrease in that order. Catalytic orders are unity for all complexes save manganese, which is 1.75. No correlation between dissociation potential and catalytic coefficient has been found, and it is believed that catalysis may be associated with the paramagnetic properties of the metal.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/app.1961.070051607
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  • 78
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    The strain dependence of rubber viscoelasticity. Part III. Natural and butyl rubber at high extensions (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 428-435 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dynamic Young's moduli are derived from observations of wave propagation in stretched filaments of natural and butyl rubbers. Extensions up to about 700% are studied within a temperature range of -45 to +50°C. and a frequency range of 0.2 to 20 kycles/sec. At constant temperature and frequency both the real (E') and imaginary (E″) components increase with increasing extension. The loss factor (E″/E') decreases with increasing extension, but the decrease is more pronounced for the butyl rubber so that the large difference in damping between the two polymers in the unstrained state is greatly reduced at high extensions. Approximate relaxation spectra are derived for the strained materials on the basis of several assumptions regarding the applicability of the WLF equation. It is found that the spectra are displaced in the direction of longer times by increasing extension; this is equivalent to an increase in the monomeric friction coefficient with extension. The effect is more pronounced for the natural rubber than for the butyl, and consequently the ratio of the friction coefficients (butyl:natural) falls from several hundred unstrained state to approximately 3 at 550% extension.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051608
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  • 79
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    Viscoelastic factors in the strength of elastomers under complex stress by a puncture methodPresented at the Tenth Canadian High Polymer Forum, Ste. Marguerite, Quebec, September 7-9, 1960.Contribution No. 262 from the research laboratory of the Goodyear Tire & Rubber Company. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 442-451 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Investigations of the viscoelastic aspects of the mechanical behavior of polymers have been limited almost exclusively to relatively simple conditions of homogeneous stress, that is, to tension or shear loadings. In the present work a study has been made from the viscoelastic standpoint of the response of several elastomers to a much more complex type of stress distribution arising from penetration up to failure by a cylindrical indentor for a range of temperatures and rates of penetration. The failure or “puncture point” was determined by a dip in the recorded curve of load versus depth of penetration. The puncture strength values were reduced to 25°C. by applying the ratio of absolute temperatures and plotted against the logarithm of the reciprocal of the rate of penetration. These curves were then shifted on the time scale to give a master curve after the manner of Tobolsky and of Ferry. The logarithms of the shift factors thus obtained were related to the reciprocal of the absolute temperature over the range studied. The results indicate a broader generality for the viscoelastic principle of time-temperature equivalence than has usually been supposed.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051610
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  • 80
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    Status of investigations for improving weatherability of linear polyethylene and copolymers (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 612-619 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In an attempt to extend the outdoor serviceability of items molded from linear polyethylene and copolymers, three ultraviolet absorbers, namely, Cyasorb UV-9 (2-hydroxy-4-methoxybenzophenone), Cyasorb UV-314 (2,2′-dihydroxy-4-n-octoxybenzophenone), and TBS (4-tert-butyl phenyl salicylate), sixteen different pigments, and combinations of both ultraviolet absorber and pigment were investigated. Injection-molded test specimens were employed in this study. The laboratory source of radiation to which these samples were exposed was an Atlas XW Weatherometer. Similar samples also were exposed at various outdoor locations including Phoenix, Arizona, Summit, New Jersey, and Newark, New Jersey, to utilize practical conditions of outdoor weathering. During these weathering studies surface cracking was observed as occurring at approximately the same time as a significant decrease in tensile strength, elongation, and melt index. Such observations became a method of rapidly screening a large number of formulations for resistance to ultraviolet radiation. For optimal outdoor serviceability with respect to retention of elongation, tensile strength, and melt index properties of molded items, the following steps are necessary. A high-density resin having as low a melt index as possible is selected. The molded item is designed to minimize the formation of molded-in stresses and strains. Proper selection of UV absorbers, pigments, and combinations of both are made. Pigments such as green, orange, peacock blue, monastral purple, red, and black, in high concentrations, will prolong the outdoor weatherability of a given product.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051717
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  • 81
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    Viscoelastic properties of regenerated cellulose sheet (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 647-654 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The viscoelastic properties of regenerated cellulose containing several different softeners or water only were investigated. Measurements of creep and Young's modulus were made on the Instron tensile tester, and the creep curves were fitted to a mechanical model consisting of Voigt and Maxwell elements of springs and dashpots in series. The elastic and viscous parameters were determined for the various softened films and compared with each other and with measurements of Young's modulus. It was found that the elastic modulus is a function of the effective molar concentration of the softener in the film which is related to its ability to break hydrogen bonds. The inelastic deformation was found to be a linear function of the heat of vaporization of softener (including water) in the film which is related to hydrogen-bonding energy. Thus, inelastic deformation requires breaking of interchain hydrogen bonds in contrast to pure elastic deformation which involves stretching of hydrogen bonds. A relationship of the Voigt unit and of the Maxwell unit on the composition of the cellulose-softener system and on cellulose-softener interaction has been demonstrated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051806
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    Polysaccharide B-1459: A new hydrocolloid polyelectrolyte produced from glucose by bacterial fermentationPresented before the Division of Carbohydrate Chemistry at the 136th National Meeting of the American Chemical Society, Atlantic City, September 1959. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 519-526 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The exocellular polysaccharide fermented from glucose in good yield by Xanthomonas campestrìs NRRL B-1459, has been characterized. The general aspects of chemical constitution have been established, as well as the physical properties related to practical applicability. This macromolecular polysaccharide is composed of D-mannose, D-glucose, D-glucuronic acid (as the potassium salt), and a small proportion of acetyl groups. It can be produced on an industrial scale and is stable is storage. Analytical fractionation indicates fairly sharp molecular distribution for the native polysaccharide. The polysaccharide forms homogeneous dispersions in water which show plastic rheological properties and viscosity comparable with that of high-grade plant gums. Outstanding characteristics of practical significance are the atypical insensitivity of solution viscosity to salt effects and to heat, especially when salt is present. Solutions of low concentration show a restricted viscosity decrease upon salt addition; those of higher concentrations show substantial increases. Viscosity is enhanced still further by monovalent cations at basic pH and by divalent cations at neutral or slightly basic pH. Salt moderates or eliminates any viscosity decrease due to heat and, in somewhat higher concentrations, it increases the viscosity of heated solutions. Heating or deacetylating Polysaccharide B-1459 causes no impairment of its properties, but actual improvement. The constitutional basis for these unusual properties is discussed.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/app.1961.070051704
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    Digital recording and automatic computation of film tensile stress-strain dataPresented at ASTM Committee D-20 Meeting, Detroit, Michigan, October 3, 1960. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 527-533 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A system is described for automatic collection of stress-strain data for polymeric films on magnetic tape for subsequent automatic data reduction and computation of a variety of stress-strain parameters. Two shaft analog-to-digital encoders attached to a conventional tensile tester feed digital information to an incremental pulse recorder which stores all stress and strain data in two channels on 0.625-in. magnetic tape. Specimen information and test constants are inserted by the operator through a keyboard located at the tensile tester. The tape is subsequently fed into a standard digital computer through a special incremental pulse magnetic tape reader. The data pulses are internally stored and converted by means of a special program into eight significant stress-strain parameters for polymeric film samples, plus averages and standard deviations for groups of replicate determinations. These parameters include: corrected length of specimen, initial maximum tensile modulus, offset yield stress, strain at break, strain at maximum stress, maximum tensile stress, tensile stress at break, and work to break. While the program described applies to polymer film testing, both it and the digital recording equipment accessories are applicable with suitable modification, to any analog experimental data. Significant savings in man-hours and increased information output result from use of this system.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051705
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  • 84
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    Effects of heterogeneous acetylation and methylation on mechanical properties of isotropic cellulose film (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 545-552 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects on mechanical properties of heterogeneous acetylation and methylation of isotropic cellulose films have been studied. The effects on breaking load, extensibility, yield point, elastic recovery, and initial Young's modulus in the air-dry state were very small. It is concluded that these properties are not markedly influenced in cellulose derivatives by variation of the nature of the intermolecular cohesive forces in the way that might have been anticipated from the analogy of a simple molecular network. It is suggested that the lack of effect of such treatments, and also the cause of the low elastic recovery in cellulose and its derivatives, may be connected with molecular stiffness, dipole distribution, and supracrystalline structure. Cellulose and its derivatives are contrasted with nylon in this respect. The effects of methylation or acetylation on mechanical properties in water are much more extensive and are attributed to a solubilizing effect which, in the case of progressive acetylation, is ultimately opposed by the formation of acetate-acetate intermolecular bonds that are relatively stable to water.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051708
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  • 85
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    Heterogeneous polymer systems. I. Torsional modulus studies (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 580-588 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Torsional modulus-temperature data have been obtained on heterogeneous polymer compositions prepared by several procedures. Both the state of aggregation of the component chain molecules and their degree of compatibility are significant variables. Modulus curves similar to those for crystalline polymers can be obtained from incompatible polymers having glass temperatures sufficiently far apart. Detailed interpretations are presented for modulus curves of both individual homopolymers and bicomponent heterogeneous polymer mixtures.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/app.1961.070051713
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  • 86
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    Grafting of vinyl monomers onto crosslinked polymers. I. Grafting of methyl methacrylate onto fibers spun from polymer blends of polyvinyl alcohol and its partially N-methylolcarbamoylethylated productsPresented at a meeting of the Chemical Society of Japan, Tokyo, October 19, 1960. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 563-573 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Improvements in physical properties of polyvinyl alcohol fibers were attempted by means of both crosslinking and graft copolymerization. By using the ceric iron redox system on synthetic fibers spun from polymer blends containing polyvinyl alcohol (PVA) and its partially (about 15 mole-%) N-methylolcarbamoylethylated products (PVM) in which the blend ratios were 0/100, 10/90, 15/85, and 20/80 by weight, methyl methacrylate (MMA) was grafted at 30°C. in the aldehyde-free acetone-water system after crosslinking by heat treatment or successive acid treatment. Grafting increases with increasing PVM component. This may be ascribed to the coarsening of the fiber texture caused by polymer blending and the increasing of methylol groups as a reducing agent. Moisture regains decrease with increasing graft fraction, but these appear to be greater than the additive values of backbone and graft polymer. Less shrinkage in boiling water is obtained with the increase of PVM component and grafting; the decreased shrinkage is significant in the acid-treated PVM-PVA fibers, and it reaches a nearly sufficient value at about 50% graft-on. The PVA fibers do not give sufficient shrink-proofing. The inherent tenacity and elongation of the grafted fibers increase slightly with increasing graft-on or denier except at the high grafting above about 100, 150, and 300 in the PVA, acid-treated, and acid-untreated PVM/PVA fibers, respectively; whereas the tensile strength in grams/denier decreases with grafting. Although at high grafting, a destruction in the fiber texture will perhaps occur, the coarser the texture of backbone fiber, the harder the change by grafting. The knot/normal ratios in tensile strength or elongation of the grafted fibers have been retained at above 90%. The elastic recovery of the grafted fibers is considerably improved as compared to the conventional Vinylon fibers. The improvements in the acid-treated and grafted PVM/PVA (20/80) fibers are significantly greater above and below 50% graft-on, especially in the range of lower extension. As expected, the thermosetting property is also appreciably imparted with grafting. In the conventional Vinylon fibers, the formalization for shrink-proofing is usually at a sacrifice of elastic recovery. But MMA grafting in the PVM/PVA fibers gives a fairly good elastic recovery and less shrinkage in addition to thermosetting property, making the most of the characteristics in the longer intermolecular crosslinkages formed between methylol groups or PVA-OH groups and methylol groups.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/app.1961.070051711
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  • 87
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    International rubber conference (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 620-620 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051718
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  • 88
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    Symposium on structure and properties of regenerated cellulosePresented before the Division of Cellulose Chemistry, at the 139th Meeting of the American Chemical Society, St. Louis, Missouri, March 21-30, 1961 (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 621-623 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051801
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  • 89
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    The resilience of chemically modified cottons. II. Reactions of cellulose with formaldehyde under acid conditions (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 704-713 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A study has been made of the reactions of cellulose with formaldehyde under acid conditions, where the fabrics are baked at elevated temperature. These treatments have involved cotton cellulose in a “dry” or relatively unswollen state and have resulted in the treated fabrics exhibiting improved crease rccovery both dry and wet. It has been found that boiling 1% acetic acid solution reduces the acetal contents of the treated fabrics and causes corresponding decreases in both dry and wet crease-recovery improvement. The reproducibility of these treatments, with respect both to extents of formaldehyde incorporation and to dry and wet crease recovery, is found to be very good within a single treatment and, more importantly, tietween different treatments carried out under the same conditions. The rates of acetal removal by the boiling 1% acetic acid and the relationships between acetal content and crease-recovery improvement have been found to be fairly complex. A study has also been made of the rates of acetal removal by boiling 1% acetic acid for samples of cotton card sliver treated with acid and subsequently heated in sealed tubes with paraformaldehyde. The rates of acetal removal in this case have been observed to be qualitatively similar to those observed for treated fabrics. The implications of these findings are discussed.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/app.1961.070051813
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  • 90
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    Polymer news (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 753-753 
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    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1961.070051818
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  • 91
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    Theis-Kaltband-Handbuch; Herausgegeben aus Anlaß des 50jährigen Bestehens der Friedr. Gustav Theis, Kaltwalzwerke, Hohenlimburg. 175 S. m. zahlr. Abb., Normen u. Tab.  -  Verlag für Wirtschaftspublizistik, Wiesbaden. (Nicht im Buchhandel.) (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 68-68 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120116
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  • 92
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    Masthead (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961) 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120201
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  • 93
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    Electronic Resource
    Über die Korrosion von Metallen in hölzernen Gehäusen (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 1-10 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Corrosion of metal in wooden casingsCertain woods (e.g. beech and oak) contain up to 5 per cent, combined acid, mainly acetic acid. During furnace drying and steam treatment, a considerable quantity of acetic acid is released which, being volatile, is liable to promote corrosion through the gaseous phase. The dependence of this acid separation on the external conditions and the escape of the acid from the wood during storage have been investigated.Corrosion tests showed that the free acetic acid of the wood does not promote corrosion until the air humidity has reached about 70 per cent. In moist basements, even normally dry and properly packed casings (e.g. clock casing) absorb so much moisture in a matter of days that steel parts begin to rust.Measures to prevent such corrosion include: storing at humidities below approx. 75 per cent., using casing made from adequately seasoned wood (which is relatively free from acid), and wrapping the steel parts to be protected (especially clocks) with VPI paper.
    Notes: Gewisse Holzarten (z.B. Buche und Eiche) enthalten bis zu 5% gebundene Säure, in der Hauptsache Essigsäure. Beim künstlichen Trocknen und beim Dämpfen spaltet sich hiervon in erheblicher Menge freie Essigsäure ab, die, da sie flüchtig ist, über die Gasphase korrosionsbegünstigend wirken kann. Die Abhängigkeit dieser Säureabspaltung von den äußeren Bedingungen und das Entweichen der Säure aus dem Holz bei der Lagerung wurden untersucht.Wie Rostversuche ergaben, wirkte die freie Essigsäure des Holzes erst bei Luftfeuchtigkeiten oberhalb etwa 80% rostbegünstigend. In feuchten Kellern nehmen auch an sich trockene, normal verpackte Gehäuse (z. B. Uhrgehäuse) in einigen Tagen soviel Feuchtigkeit auf, daß Stahlteile zu rosten beginnen.Maßnahmen zur Korrosionsverhütung sind: Lagerung bei Feuchtigkeiten unterhalb etwa 75%, Herstellung der Gehäuse aus genügend abgelagertem und damit säurearmem Holz, Umhüllung der zu schützenden Stahlteile (im besonderen bei Uhren) mit VPI-Papier.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120102
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  • 94
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    Electronic Resource
    Überzüge organischer Natur (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 46-58 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120110
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  • 95
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    Electronic Resource
    Corrosion Data Survey, 1960 Edition, compiled by G. A. Nelson, Copyright 1950, 1954, 1960 Shell Development Company, Emeryville, California (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 68-68 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120114
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  • 96
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    Electronic Resource
    Aus Industrie und Technik (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 70-72 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120118
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  • 97
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    Electronic Resource
    Allgemeines, Theorie und Messung der Korrosion (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 88-98 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120205
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  • 98
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    Electronic Resource
    Nichteisenmetalle (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 107-110 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120207
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  • 99
    Electronic Resource
    Electronic Resource
    Beitrag zur Systematik der Korrosion der Metalle im Erdreich VI (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 85-88 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: The systematology of the corrosion of metals in soil (VI) Lead, zinc and aluminum coatingsThe results of the field tests carried out by the U.S. Bureau of Standards with metallic coatings in U.S. soils have been evaluated on the basis of the results obtained and published so far. It was found that the resistance of lead coatings on iron pipes depends on the duration of the test, on the pH value of the soil, and on the average annual rainfall. In this respect, it was possible to find simple relationships explaining the behaviour of „parkway cable“ in different U.S. soils. Similarly, it was possible to find a simple law governing the longterm corrosion behaviour of galvanized iron' pipes buried in the soil. Like the behaviour of metallic coatings in new electrolytes, the behaviour of metallic coatings in the soil can be illustrated by corrosion rate/pH diagrams. The resistance of dip and powder calorized iron pipes depends on the pH value of the soil, and on its airing.
    Notes: Die Ergebnisse der von US-Bureau of Standards mit metallischen Überzügen in USA-Böden durchgeführten Naturkorrosionsversuche wurden unter Zugrundelegung der bisher gewonnenen und bekanntgegebene Erkenntnisse ausgewertet. Dabie wurde festgestellt, daß die Widerstandsfähigkeit von Bleiüberzügen auf Eisenrohren von der Versuchsdauer, dem pH-Wert des Bodens und der durchschnittlichen jährlichen Regenmenge abhängt. Für das Verhalten von „parkway cable„ in verschiedenen USA-Böden konnten in dieser Hinsicht einfache Zusammenhänge gefunden werden. Verzinkte Eisenrohre ließen ebenfalls im Erdboden hinsichtlich ihres Korrosions-Dauerverhaltens eine einfache Gesetzmäßigkeit erkennen. Für das Verhalten der verschiedenen metallischen Überzüge im Erdreich können ähnlich wie für deren Verhalten im neuen Elektrolyten, Korrosionsgeschwindigkeits-pH-Diagramme entwickelt werden. Die Widerstandsfähigkeit von tauch- und pulverkalorisierten Eisenrohren hängt vom pH-Wert des Bodens und von dessen Belüftung ab.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120204
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  • 100
    Electronic Resource
    Electronic Resource
    Eisenmetalle (1961)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 12 (1961), S. 300-303 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19610120507
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