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  • 1
    Electronic Resource
    Electronic Resource
    Shifted-contour auxiliary-field Monte Carlo for molecular electronic structure (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 8241-8248 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The shifted-contour auxiliary-field Monte Carlo (SCAFMC) approach has been recently developed by Rom, Charutz and Neuhauser as an extension of the auxiliary-field Monte Carlo (AFMC) method. AFMC replaces the difficult fully interacting electrons problem by an ensemble of simpler problems where the electrons interact with a fluctuating electric field but not with each other. SCAFMC is based on shifting the auxiliary-field contour of integration to pass through the (imaginary) stationary point, leading to numerical stability at long propagation times. The new approach converges to the full CI energy in electronic structure calculations (both ground and low-lying excited states). Here we expand the application of SCAFMC from atomic to molecular problems. First, we calculate ground-state energies of a highly correlated transition-metal system (Cr2) with a moderate (12 orbitals) active space size, and demonstrate that SCAFMC is able to extract the energies accurately. In addition, we use SCAFMC to calculate a C–C bond-stretch energy in ethane with complete active spaces of up to 28 orbitals. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477486
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  • 2
    Electronic Resource
    Electronic Resource
    Initial state laser control of curve-crossing reactions using the Rayleigh–Ritz variational procedure (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 7045-7051 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new two-step procedure for laser control of photodissociation is presented. In the first step of the procedure, we show that control of photodissociation product yields can be exerted through preparation of the initial wave function prior to application of the photodissociation field in contrast to previous laser control studies where attention has focused on the design of the field which induces dissociation. Specifically, for a chosen channel from which maximum product yield is desired and a given photodissociation field, the optimal linear combination of vibrational eigenstates which comprise the initial wave function is found using a straightforward variational calculation. Any photodissociation pulse shape and amplitude can be assumed since the Schrödinger equation is solved directly. Application of this method to control of product yields in the photodissociation of hydrogen iodide is demonstrated. The second step of the control procedure involves the preparation of the coherent superposition of discrete levels obtained from the previous step; design of the preparatory field can be done analytically for two or three level systems as demonstrated here or with other well-studied iterative field design methods. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471421
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  • 3
    Electronic Resource
    Electronic Resource
    Minimum utility cost of mass exchange networks with variable single component supplies and targets (1993)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 32 (1993), S. 1937-1950 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00021a018
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  • 4
    Electronic Resource
    Electronic Resource
    Oxygen-dependent and -independent mechanisms of renal injury in experimental ascending pyelonephritis (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 13 (1996), S. 0 
    Details
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract Pyelonephritis is the most common urinary tract infection affecting females of all age groups. Despite concerted efforts the mechanism of renal injury in pyelonephritis is not clearly understood. In the present study we have made an attempt to characterise the mediators of inflammatory insult in an experimental model of ascending pyelonephritis. Mice infected with Escherichia coli O6:K13:H1 were sacrificed at 2, 7 and 14 days post-infection. Luminol-dependent chemiluminescence response, NADPH oxidase, acid phosphatase, β-glucuronidase and N-acetyl-β-d-glucosaminidase activities were monitored in circulating as well as renal phagocytic cells in order to determine the role of reactive oxygen species and lysosomal enzymes in genesis of renal injury. We have demonstrated that reactive oxygen species are generated at the initiation of infection and the levels increase progressively during the course of infection. While intracellular release of lysosomal enzymes was seen in all groups, extracellular release was primarily observed at 7 and 14 days post-infection only. The results indicate that while reactive oxygen species play a significant role in tissue injury during all stages of infection, lysosomal enzyme release in extracellular milieu augments tissue destruction at later stages only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-695X.1996.tb00213.x
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  • 5
    Electronic Resource
    Electronic Resource
    Constraint management on distributed design configurations (1995)
    Springer
    Engineering with computers 11 (1995), S. 199-212 
    Details
    ISSN: 1435-5663
    Keywords: collaborative engineering ; configurations ; constraint management ; distributed databases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Architecture, engineering and construction (AEC) design processes involve the participation of many designers who may work independently in geographically distinct locations. Independent designs evolve owing to changes made by the designers and discipline-specific CAD applications, and these changes need to be evaluated and configured with respect to a set of project constraints for overall design consistency. In addition, each designer needs to be informed about the relevant changes made by other designers. Most rework orders result from inadequate sharing of the evolving design information between various participants in the design process. The awareness of important changes through automatedconstraint management can avoid expensive reworks at the later stages of the projects. In this paper, we present an incremental approach to constraint checking in AEC design configurations. A configuration represents a design state stored in multiple databases: each configuration has a set ofdiscipline-specific databases and an associated set ofinter-disciplinary constraints. The constraints are evaluated on the databases to give the third component of configurations: a set ofviolations. Including violations in the configuration definition allows us to support partially consistent configurations. Partially consistent configurations are important from a practical standpoint since all the design information may not be available, or may not be consistent, at all stages of the AEC design process. We provide a formal description ofconfigurations and the semantics of changes on configurations. This framework facilitates incremental constraint checking to support the notions ofpersistent andwhat-if configurations. We also provide a classification of constraints that is helpful in selective evaluation of constraints.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01208814
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  • 6
    Electronic Resource
    Electronic Resource
    Variable target mass-exchange network synthesis through linear programming (1996)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1326-1340 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mass-exchange network (MEN) synthesis problem is considered with streams whose target compositions are allowed to vary between upper and lower bounds. The design task is to determine the minimum mass separating agent (utility) cost needed for the transfer of a single component from the rich to the lean streams. The mathematical formulation of this synthesis problem leads to a mixed integer nonlinear program. In this work, we propose a novel formulation of the problem that leads to a linear program. Stream decomposition is employed in attaining this novel linear programming formulation and rigorous proofs are presented which establish that the two formulations have the same solution. The linear programming formulation reduces the complexity of the considered MEN synthesis problem, thus making feasible its solution even for large-scale problems. Two examples, illustrating the procedure, are presented. Both demonstrate that significant utility cost savings can be achieved over the fixed composition MEN synthesis problem.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690420513
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  • 7
    Electronic Resource
    Electronic Resource
    An underwood-like model for a finite mass exchanger (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1843-1851 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model is presented for a multicomponent, two-stream, countercurrent mass exchanger with a finite number of stages. The model relates the outlet compositions to the inlet compositions and the flow rate ratio of the two streams going through the exchanger, as well as the number of stages in the exchanger. An iterative solution procedure employing this model is proposed for the mass exchanger design problem. The model requires solution of a polynomial equation whose roots may be complex. Bounds to the real roots of the polynomial have also been established. Two examples illustrating how the method is employed are presented. The second example demonstrates that the iterative procedure converges even in the complex domain, and that complex roots exist for a real column.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410803
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  • 8
    Electronic Resource
    Electronic Resource
    Capabilities-Based Query Rewriting in Mediator Systems (1998)
    Springer
    Distributed and parallel databases 6 (1998), S. 73-110 
    Details
    ISSN: 1573-7578
    Keywords: heterogeneous sources ; mediator systems ; query rewriting ; query containment ; cost optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Users today are struggling to integrate a broad range of information sources providing different levels of query capabilities. Currently, data sources with different and limited capabilities are accessed either by writing rich functional wrappers for the more primitive sources, or by dealing with all sources at a “lowest common denominator”. This paper explores a third approach, in which a mediator ensures that sources receive queries they can handle, while still taking advantage of all of the query power of the source. We propose an architecture that enables this, and identify a key component of that architecture, the Capabilities-Based Rewriter (CBR). The CBR takes as input a description of the capabilities of a data source, and a query targeted for that data source. From these, the CBR determines component queries to be sent to the sources, commensurate with their abilities, and computes a plan for combining their results using joins, unions, selections, and projections. We provide a language to describe the query capability of data sources and a plan generation algorithm. Our description language and plan generation algorithm are schema independent and handle SPJ queries. We also extend CBR with a cost-based optimizer. The net effect is that we prune without losing completeness. Finally we compare the implementation of a CBR for the Garlic project with the algorithms proposed in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008646830769
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