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  • 101
    Publikationsdatum: 2024-03-06
    Beschreibung: In this article, we introduce the Maximum Diversity Assortment Selection Problem (MDASP), which is a generalization of the two-dimensional Knapsack Problem (2D-KP). Given a set of rectangles and a rectangular container, the goal of 2D-KP is to determine a subset of rectangles that can be placed in the container without overlapping, i.e., a feasible assortment, such that a maximum area is covered. MDASP is to determine a set of feasible assortments, each of them covering a certain minimum threshold of the container, such that the diversity among them is maximized. Thereby, diversity is defined as the minimum or average normalized Hamming distance of all assortment pairs. MDASP was the topic of the 11th AIMMS-MOPTA Competition in 2019. The methods described in this article and the resulting computational results won the contest. In the following, we give a definition of the problem, introduce a mathematical model and solution approaches, determine upper bounds on the diversity, and conclude with computational experiments conducted on test instances derived from the 2D-KP literature.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 102
    Publikationsdatum: 2024-03-18
    Sprache: Englisch
    Materialart: researchdata , doc-type:ResearchData
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  • 103
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2024-03-18
    Beschreibung: Python implementation of severals tools (PCCA, AJC, SQRA, P/Q estimation) for the analysis of dynamical systems from the transfer operator perspective.
    Sprache: Englisch
    Materialart: software , doc-type:Other
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  • 104
    Publikationsdatum: 2024-03-18
    Beschreibung: The dynamical behavior of social systems can be described by agent-based models. Although single agents follow easily explainable rules, complex time-evolving patterns emerge due to their interaction. The simulation and analysis of such agent-based models, however, is often prohibitively time-consuming if the number of agents is large. In this paper, we show how Koopman operator theory can be used to derive reduced models of agent-based systems using only simulation or real-world data. Our goal is to learn coarse-grained models and to represent the reduced dynamics by ordinary or stochastic differential equations. The new variables are, for instance, aggregated state variables of the agent-based model, modeling the collective behavior of larger groups or the entire population. Using benchmark problems with known coarse-grained models, we demonstrate that the obtained reduced systems are in good agreement with the analytical results, provided that the numbers of agents is sufficiently large.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 105
    Publikationsdatum: 2024-03-18
    Beschreibung: Modeling, simulation and analysis of interacting agent systems is a broad field of research, with existing approaches reaching from informal descriptions of interaction dynamics to more formal, mathematical models. In this paper, we study agent-based models (ABMs) given as continuous-time stochastic processes and their pathwise approximation by ordinary and stochastic differential equations (ODEs and SDEs, respectively) for medium to large populations. By means of an appropriately adapted transfer operator approach we study the behavior of the ABM process on long time scales. We show that, under certain conditions, the transfer operator approach allows to bridge the gap between the pathwise results for large populations on finite timescales, i.e., the SDE limit model, and approaches built to study dynamical behavior on long time scales like large deviation theory. The latter provides a rigorous analysis of rare events including the associated asymptotic rates on timescales that scale exponentially with the population size. We demonstrate that it is possible to reveal metastable structures and timescales of rare events of the ABM process by finite-length trajectories of the SDE process for large enough populations. This approach has the potential to drastically reduce computational effort for the analysis of ABMs.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 106
    Publikationsdatum: 2024-04-05
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 107
    Publikationsdatum: 2024-04-05
    Beschreibung: This thesis is concerned with the wide field of feature tracking in time-dependent data. Many solutions already exist for the tracking of various features in scalar fields that are given as discrete time steps. In the field of meteorology, recently published precipitation data of the COSMO-REA2 reanalysis system gave rise to the analysis of precipitation at a convective scale for which a tracking of precipitation cells over time is desired. A previous study indicated that a tracking based on the widely used overlap criterion does not perform well for the reanalysis data. Based on a novel set of requirements, a new approach to the tracking of regions in time-dependent scalar fields is developed in the course of this thesis and applied in a prototypical study to example datasets of the COSMO-REA2 system. Despite the concrete motivation of using the developed method for subsequent studies of precipitation, the tracking approach is designed to be applicable for arbitrary scalar quantities that can conceptually be given on uniform grids of arbitrary dimensions. Based on a detailed description of the utilized methods, this thesis presents a novel tracking solution whose correspondence identification is based on image registration of successive time steps in combination with a hierarchical watershed segmentation by means of which features are extracted. The proposed implementation allows for an efficient generation of tracking results under the premise that the registration-based correspondence information has been precomputed.
    Sprache: Englisch
    Materialart: masterthesis , doc-type:masterThesis
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  • 108
    Publikationsdatum: 2024-04-26
    Beschreibung: The traditional linear regression model that assumes normal residuals is applied extensively in engineering and science. However, the normality assumption of the model residuals is often ineffective. This drawback can be overcome by using a generalized normal regression model that assumes a non-normal response. In this paper, we propose regression models based on generalizations of the normal distribution. The proposed regression models can be used effectively in modeling data with a highly skewed response. Furthermore, we study in some details the structural properties of the proposed generalizations of the normal distribution. The maximum likelihood method is used for estimating the parameters of the proposed method. The performance of the maximum likelihood estimators in estimating the distributional parameters is assessed through a small simulation study. Applications to two real datasets are given to illustrate the flexibility and the usefulness of the proposed distributions and their regression models.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 109
    Publikationsdatum: 2024-04-26
    Beschreibung: Compressor stations are the heart of every high-pressure gas transport network. Located at intersection areas of the network they are contained in huge complex plants, where they are in combination with valves and regulators responsible for routing and pushing the gas through the network. Due to their complexity and lack of data compressor stations are usually dealt with in the scientific literature in a highly simplified and idealized manner. As part of an ongoing project with one of Germany's largest Transmission System Operators to develop a decision support system for their dispatching center, we investigated how to automatize control of compressor stations. Each station has to be in a particular configuration, leading in combination with the other nearby elements to a discrete set of up to 2000 possible feasible operation modes in the intersection area. Since the desired performance of the station changes over time, the configuration of the station has to adapt. Our goal is to minimize the necessary changes in the overall operation modes and related elements over time, while fulfilling a preset performance envelope or demand scenario. This article describes the chosen model and the implemented mixed integer programming based algorithms to tackle this challenge. By presenting extensive computational results on real world data we demonstrate the performance of our approach.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 110
    Publikationsdatum: 2024-04-26
    Beschreibung: The ongoing energy transition introduces new challenges for distribution networks and brings about the need to expand existing power grid capacities. In order to contain network expansion and with it economic costs, utilization of various flexibility options to reduce expansion needs is discussed. This paper proposes a multiperiod optimal power flow (MPOPF) approach with a new continuous network expansion formulation to optimize the deployment of flexibility options under the objective of minimizing network expansion costs. In a comparison of the newly proposed continuous network expansion formulation with an existing mixed integer formulation and a continuous interpretation of the latter the here proposed formulation is shown to be useful in order to obtain a solvable problem and contain computational efforts. The presented MPOPF including the flexibility options storage units and curtailment is then assessed on synthetic medium voltage grids and applied to evaluate the benefit of a combined vs. a stepwise optimization of these flexibility options. It is demonstrated that using a local solver the proposed approach is applicable and yields a solution in reasonable time. Furthermore, it is shown that the combined optimization generally leads to a more efficient utilization of the considered flexibility options and therefore lower grid expansion costs than the stepwise consideration.
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 111
    Publikationsdatum: 2024-04-26
    Beschreibung: With annual consumption of approx. 95 billion cubic me-ters and similar amounts of gas just transshipped through Germany toother EU states, Germany’s gas transport system plays a vital role inEuropean energy supply. The complex, more than 40,000 km long high-pressure transmission network is controlled by several transmission sys-tem operators (TSOs) whose main task is to provide security of supplyin a cost-efficient way. Given the slow speed of gas flows through the gastransmission network pipelines, it has been an essential task for the gasnetwork operators to enhance the forecast tools to build an accurate andeffective gas flow prediction model for the whole network. By incorpo-rating the recent progress in mathematical programming and time seriesmodeling, we aim to model natural gas network and predict gas in- andout-flows at multiple supply and demand nodes for different forecastinghorizons. Our model is able to describe the dynamics in the network bydetecting the key nodes, which may help to build an optimal manage-ment strategy for transmission system operators.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 112
    Publikationsdatum: 2024-04-26
    Beschreibung: Germany is the largest market for natural gas in the European Union, with an annual consumption of approx. 95 billion cubic meters. Germany's high-pressure gas pipeline network is roughly 40,000 km long, which enables highly fluctuating quantities of gas to be transported safely over long distances. Considering that similar amounts of gas are also transshipped through Germany to other EU states, it is clear that Germany's gas transport system is essential to the European energy supply. Since the average velocity of gas in a pipeline is only 25km/h, an adequate high-precision, high-frequency forecasting of supply and demand is crucial for efficient control and operation of such a transmission network. We propose a deep learning model based on spatio-temporal convolutional neural networks (DLST) to tackle the problem of gas flow forecasting in a complex high-pressure transmission network. Experiments show that our model effectively captures comprehensive spatio-temporal correlations through modeling gas networks and consistently outperforms state-of-the-art benchmarks on real-world data sets by at least 21%. The results demonstrate that the proposed model can deal with complex nonlinear gas network flow forecasting with high accuracy and effectiveness.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 113
    Publikationsdatum: 2024-04-26
    Beschreibung: Germany is the largest market for natural gas in the European Union, with an annual consumption of approx. 95 billion cubic meters. Germany's high-pressure gas pipeline network is roughly 40,000 km long, which enables highly fluctuating quantities of gas to be transported safely over long distances. Considering that similar amounts of gas are also transshipped through Germany to other EU states, it is clear that Germany's gas transport system is essential to the European energy supply. Since the average velocity of gas in a pipeline is only 25km/h, an adequate high-precision, high-frequency forecasting of supply and demand is crucial for efficient control and operation of such a transmission network. We propose a deep learning model based on spatio-temporal convolutional neural networks (DLST) to tackle the problem of gas flow forecasting in a complex high-pressure transmission network. Experiments show that our model effectively captures comprehensive spatio-temporal correlations through modeling gas networks and consistently outperforms state-of-the-art benchmarks on real-world data sets by at least 21$\%$. The results demonstrate that the proposed model can deal with complex nonlinear gas network flow forecasting with high accuracy and effectiveness.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 114
    Publikationsdatum: 2024-04-26
    Beschreibung: In designing energy supply systems, designers should heighten the robustness in performance criteria against the uncertainty in energy demands. In this paper, a robust optimal design method using a hierarchical mixed-integer linear programming (MILP) method is proposed to maximize the robustness of energy supply systems under uncertain energy demands based on a mixed-integer linear model. A robust optimal design problem is formulated as a three-level min-max-min MILP one by expressing uncertain energy demands by intervals, evaluating the robustness in a performance criterion based on the minimax regret criterion, and considering relationships among integer design variables, uncertain energy demands, and integer and continuous operation variables. This problem is solved by evaluating upper and lower bounds for the minimum of the maximum regret of the performance criterion repeatedly outside, and evaluating lower and upper bounds for the maximum regret repeatedly inside. Different types of optimization problems are solved by applying a hierarchical MILP method developed for ordinary optimal design problems without and with its modifications. In a case study, the proposed approach is applied to the robust optimal design of a cogeneration system. Through the study, its validity and effectiveness are ascertained, and some features of the obtained robust designs are clarified.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 115
    Publikationsdatum: 2024-04-26
    Beschreibung: We propose a mathematical optimization model and its solution for joint chance constrained DC Optimal Power Flow. In this application, it is particularly important that there is a high probability of transmission limits being satisfied, even in the case of uncertain or fluctuating feed-in from renewable energy sources. In critical network situations where the network risks overload, renewable energy feed-in has to be curtailed by the transmission system operator (TSO). The TSO can reduce the feed-in in discrete steps at each network node. The proposed optimization model minimizes curtailment while ensuring that there is a high probability of transmission limits being maintained. The latter is modeled via (joint) chance constraints that are computationally challenging. Thus, we propose a solution approach based on the robust safe approximation of these constraints. Hereby, probabilistic constraints are replaced by robust constraints with suitably defined uncertainty sets constructed from historical data. The ability to discretely control the power feed-in then leads to a robust optimization problem with decision-dependent uncertainties, i.e. the uncertainty sets depend on decision variables. We propose an equivalent mixed-integer linear reformulation for box uncertainties with the exact linearization of bilinear terms. Finally, we present numerical results for different test cases from the Nesta archive, as well as for a real network. We consider the discrete curtailment of solar feed-in, for which we use real-world weather and network data. The experimental tests demonstrate the effectiveness of this method and run times are very fast. Moreover, on average the calculated robust solutions only lead to a small increase in curtailment, when compared to nominal solutions.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 116
    Publikationsdatum: 2024-04-26
    Beschreibung: The mixed-integer linear programming (MILP) method has been applied widely to optimal design of energy supply systems. A hierarchical MILP method has been proposed to solve such optimal design problems efficiently. In addition, a method of reducing model by time aggregation has been proposed to search design candidates accurately and efficiently at the upper level. In this paper, the hierarchical MILP method and model reduction by time aggregation are applied to the multiobjective optimal design. The methods of clustering periods by the order of time series, by the k-medoids method, and based on an operational strategy are applied for the model reduction. As a case study, the multiobjective optimal design of a gas turbine cogeneration system is investigated by adopting the annual total cost and primary energy consumption as the objective functions, and the clustering methods are compared with one another in terms of the computation efficiency. It turns out that the model reduction by any clustering method is effective to enhance the computation efficiency when importance is given to minimizing the first objective function, but that the model reduction only by the k-medoids method is effective very limitedly when importance is given to minimizing the second objective function.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 117
    Publikationsdatum: 2024-04-26
    Beschreibung: In many business and economics studies, researchers have sought to measure the dynamic dependence of curves with high-dimensional mixed-type predictors. We propose a partially functional autoregressive model (pFAR) where the serial dependence of curves is controlled by coefficient operators that are defined on a two-dimensional surface, and the individual and group effects of mixed-type predictors are estimated with a two-layer regularization. We develop an efficient estimation with the proven asymptotic properties of consistency and sparsity. We show how to choose the sieve and tuning parameters in regularization based on a forward-looking criterion. In addition to the asymptotic properties, numerical validation suggests that the dependence structure is accurately detected. The implementation of the pFAR within a real-world analysis of dependence in German daily natural gas flow curves, with seven lagged curves and 85 scalar predictors, produces superior forecast accuracy and an insightful understanding of the dynamics of natural gas supply and demand for the municipal, industry, and border nodes, respectively.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 118
    Publikationsdatum: 2024-04-26
    Sprache: Englisch
    Materialart: doctoralthesis , doc-type:doctoralThesis
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  • 119
    Publikationsdatum: 2024-04-26
    Beschreibung: As a result of the legislation for gas markets introduced by the European Union in 2005, separate independent companies have to conduct the transport and trading of natural gas. The current gas market of Germany, which has a market value of more than 54 billion USD, consists of Transmission System Operators (TSO), network users, and traders. Traders can nominate a certain amount of gas anytime and anywhere in the network. Such unrestricted access for the traders, on the other hand, increase the uncertainty in the gas supply management. Some customers’ behaviors may cause abrupt structural changes in gas flow time series. In particular, it is a challenging task for the TSO operators to predict gas nominations 6 to 10 hours ahead. In our study, we aim to investigate the regime changes in the time series of nominations to predict the 6 to 10 hours ahead of gas nominations.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 120
    Publikationsdatum: 2024-04-26
    Beschreibung: Lattice problems are a class of optimization problems that are notably hard. There are no classical or quantum algorithms known to solve these problems efficiently. Their hardness has made lattices a major cryptographic primitive for post-quantum cryptography. Several different approaches have been used for lattice problems with different computational profiles; some suffer from super-exponential time, and others require exponential space. This motivated us to develop a novel lattice problem solver, CMAP-LAP, based on the clever coordination of different algorithms that run massively in parallel. With our flexible framework, heterogeneous modules run asynchronously in parallel on a large-scale distributed system while exchanging information, which drastically boosts the overall performance. We also implement full checkpoint-and-restart functionality, which is vital to high-dimensional lattice problems. Through numerical experiments with up to 103,680 cores, we evaluated the performance and stability of our system and demonstrated its high capability for future massive-scale experiments.
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 121
    Publikationsdatum: 2024-04-26
    Beschreibung: Lattice problems are a class of optimization problems that are notably hard. There are no classical or quantum algorithms known to solve these problems efficiently. Their hardness has made lattices a major cryptographic primitive for post-quantum cryptography. Several different approaches have been used for lattice problems with different computational profiles; some suffer from super-exponential time, and others require exponential space. This motivated us to develop a novel lattice problem solver, CMAP-LAP, based on the clever coordination of different algorithms that run massively in parallel. With our flexible framework, heterogeneous modules run asynchronously in parallel on a large-scale distributed system while exchanging information, which drastically boosts the overall performance. We also implement full checkpoint-and-restart functionality, which is vital to high-dimensional lattice problems. Through numerical experiments with up to 103,680 cores, we evaluated the performance and stability of our system and demonstrated its high capability for future massive-scale experiments.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 122
    Publikationsdatum: 2024-04-26
    Beschreibung: In the transition towards a pure hydrogen infrastructure, utilizing the existing natural gas infrastructure is a necessity. In this study, the maximal technically feasible injection of hydrogen into the existing German natural gas transmission network is analysed with respect to regulatory limits regarding the gas quality. We propose a transient tracking model based on the general pooling problem including linepack. The analysis is conducted using real-world hourly gas flow data on a network of about 10,000 km length.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 123
    Publikationsdatum: 2024-04-26
    Beschreibung: For cryptanalysis in lattice-based schemes, the performance evaluation of lattice basis reduction using high-performance computers is becoming increasingly important for the determination of the security level. We propose a distributed and asynchronous parallel reduction algorithm based on randomization and DeepBKZ, which is an improved variant of the block Korkine-Zolotarev (BKZ) reduction algorithm. Randomized copies of a lattice basis are distributed to up to 103,680 cores and independently reduced in parallel, while some basis vectors are shared asynchronously among all processes via MPI. There is a trade-off between randomization and information sharing; if a substantial amount of information is shared, all processes will work on the same problem, thereby diminishing the benefit of parallelization. To monitor this balance between randomness and sharing, we propose a metric to quantify the variety of lattice bases. We empirically find an optimal parameter of sharing for high-dimensional lattices. We demonstrate the efficacy of our proposed parallel algorithm and implementation with respect to both performance and scalability through our experiments.
    Sprache: Englisch
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  • 124
    Publikationsdatum: 2024-04-26
    Beschreibung: The stability of flows in porous media plays a vital role in transiting energy supply from natural gas to hydrogen, especially for estimating the usability of existing underground gas storage infrastructures. Thus, this research aims to analyze the interface stability of the tangential-velocity discontinuity between two compressible gases by using Darcy's model to include the porosity effect. The results shown in this research will be a basis for considering whether underground gas storages in porous material can be used to store hydrogen. We show the relation between the Mach number M, the viscosity \mu, and the porosity \epsilon on the stability of the interface. This interface stability affects gases' withdrawal and injection processes, thus will help us to determine the velocity which with gas can be extracted and injected into the storage effectively. By imposing solid walls along the flow direction, the critical values of these parameters regarding the stability of the interface are smaller than when considering no walls. The consideration of bounded flows approaches the problem more realistically. In particular, this analysis plays a vital role when considering two-dimensional gas flows in storages and pipes.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 125
    Publikationsdatum: 2024-04-26
    Beschreibung: It is well known that the interface between two regions of an incompressible ideal fluid flow moving in a relative motion is necessarily destabilized, regardless of the velocity difference's strength. This phenomenon is the so-called Kelvin-Helmholtz instability (KHI). However, a large number of works demonstrated a surprising result that the instability is suppressed for shallow water flows; the interface is stabilized if the Froude number, defined by the velocity difference's ratio to the gravity wave's speed, is sufficiently large. In a limited way, these authors have been used the shallow-water equations without the higher-order effect of the dispersive terms. Thus, this investigation aims to examine these higher-order dispersive effects to analyze the interface stability problem of tangential-velocity discontinuity in shallow-water flows. In particular, we use the Green-Naghdi equations to introduce the dispersive terms related to the depth and the depth-averaged horizontal velocities of the fluid. We show that the interface stability depends on the Froude number (i.e., the velocity difference's strength) and the water depth. A critical value of the Froude number to stabilize the interface is smaller than the case of no dispersive terms, and the flow in a deeper region is more stable than in a shallower one. We also consider the distribution of kinetic and potential energy to clarify a feature characteristic of a large class of instabilities in shallow water flow. The instability of flows is caused by the decrease in the kinetic energy during the perturbation of waves. This phenomenon is known as negative energy modes and plays a vital role in applying the model to industrial equipment. A conclusion is that the equipartition of energies occurs if and only if the velocity difference is zero and the water depth is shallow enough to ignore the dispersive terms.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 126
    Publikationsdatum: 2024-04-26
    Beschreibung: Compressible flows appear in many natural and technological processes, for instance, the flow of natural gases in a pipe system. Thus, a detailed study of the stability of tangential velocity discontinuity in compressible media is relevant and necessary. The first early investigation in two-dimensional (2D) media was given more than 70 years ago. In this article, we continue investigating the stability in three-dimensional (3D) media. The idealized statement of this problem in an infinite spatial space was studied by Syrovatskii in 1954. However, the omission of the absolute sign of cos θ with θ being the angle between vectors of velocity and wave number in a certain inequality produced the inaccurate conclusion that the flow is always unstable for entire values of the Mach number M. First, we revisit this case to arrive at the correct conclusion, namely that the discontinuity surface is stabilized for a large Mach number with a given value of the angle θ. Next, we introduce a real finite spatial system such that it is bounded by solid walls along the flow direction. We show that the discontinuity surface is stable if and only if the dispersion relation equation has only real roots, with a large value of the Mach number; otherwise, the surface is always unstable. In particular, we show that a smaller critical value of the Mach number is required to make the flow in a narrow channel stable.
    Sprache: Englisch
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  • 127
    Publikationsdatum: 2024-04-26
    Sprache: Englisch
    Materialart: doctoralthesis , doc-type:doctoralThesis
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  • 128
    Publikationsdatum: 2024-05-16
    Beschreibung: We study the romanization process of northern Africa from 50 BC till 300 AD. Our goal is to infer the communication strength between different subregions, based on the evolution of the status of cities. Herefore, we use the general inverse infection model, that infers the weights of a known underlying network, given observations of the spreading on this network. As infection process we choose the SI metapopulation model, where I stands for a city with a Roman status. To solve the minimization problem we use the particle swarm optimization algorithm with a specific choice of parameters.
    Sprache: Deutsch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 129
    Publikationsdatum: 2024-06-13
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 130
    Titel: Grundlagen der Eingruppierung TVöD und TV-L : das aktuelle Eingruppierungsrecht im öffentlichen Dienst
    Autor: Richter, Achim
    Beteiligte Person(en): Gamisch, Annett , Mohr, Thomas
    Ausgabe: 7., aktualisierte Auflage, Bearbeitungsstand: Juni 2017
    Verlag: Berlin :Walhalla und Praetoria Verlag,
    Erscheinungsjahr: 2021
    Seiten: 112 Seiten
    ISBN: 978-3-8029-1599-4
    Materialart: Buch
    Sprache: Deutsch
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  • 131
    Titel: Crashkurs BWA : betriebswirtschaftliche Auswertungen erstellen, lesen und verstehen
    Autor: Träger, Elisabeth
    Ausgabe: 1. Auflage
    Erscheinungsjahr: 2021
    Seiten: 180 Seiten
    ISBN: 978-3-648-13768-0
    Materialart: Buch
    Sprache: Deutsch
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  • 132
    Buch
    Buch
    Freiburg im Breisgau :Haufe-Lexware,
    Titel: Schwierige Geschäftsvorfälle richtig buchen /
    Autor: Thomsen, Iris
    Beteiligte Person(en): Zöllner, Nikolaus
    Ausgabe: 15. Auflage
    Verlag: Freiburg im Breisgau :Haufe-Lexware,
    Erscheinungsjahr: 2021
    Seiten: 413 Seiten
    ISBN: 978-3-648-14840-2
    Materialart: Buch
    Sprache: Deutsch
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  • 133
    Buch
    Buch
    München :C.H. Beck,
    Titel: Erfurter Kommentar zum Arbeitsrecht
    Beteiligte Person(en): Müller-Glöge, Rudi , Preis, Ulrich , Gallner, Inken
    Ausgabe: 22. Auflage
    Verlag: München :C.H. Beck,
    Erscheinungsjahr: 2021
    Seiten: 3100 Seiten
    ISBN: 978-3-406-77038-8
    Materialart: Buch
    Sprache: Deutsch
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  • 134
    Buch
    Buch
    Beijing ; Boston ; Farnham ; Sebastopol :O'Reilly,
    Titel: Programming Rust : fast, safe systems development
    Autor: Blandy, Jim
    Beteiligte Person(en): Orendorff, Jason , Tindall, Leonora
    Ausgabe: Second edition
    Verlag: Beijing ; Boston ; Farnham ; Sebastopol :O'Reilly,
    Erscheinungsjahr: 2021
    Seiten: xix, 711 Seiten
    ISBN: 9781492052562
    Materialart: Buch
    Sprache: Englisch
    Paralleltitel: Erscheint auch als Druck-Ausgabe 978-1-492-05259-3
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  • 135
    Buch
    Buch
    Weinheim :Wiley-VCH,
    Titel: Git für Dummies /
    Autor: Kaufmann, Michael
    Beteiligte Person(en): Binkle, Harald
    Verlag: Weinheim :Wiley-VCH,
    Erscheinungsjahr: 2021
    Seiten: 417 Seiten
    ISBN: 978-3-527-71697-5
    Materialart: Buch
    Sprache: Deutsch
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  • 136
    Buch
    Buch
    Landshut :BMU Media Verlag,
    Titel: Git Handbuch für Einsteiger : Der leichte Weg zum Git-Experten
    Autor: Fuchs, Paul
    Verlag: Landshut :BMU Media Verlag,
    Erscheinungsjahr: 2021
    Seiten: 307 Seiten
    ISBN: 978-3-96645-119-2
    Materialart: Buch
    Sprache: Deutsch
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  • 137
    Buch
    Buch
    Sincxpress Bv,
    Titel: Linear Algebra : Theory, Intuition, Code
    Autor: Cohen, Mike X
    Verlag: Sincxpress Bv,
    Erscheinungsjahr: 2021
    Seiten: 548 S.
    ISBN: 978-90-831366-0-8
    Materialart: Buch
    Sprache: Deutsch
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  • 138
    Buch
    Buch
    Bonn :Rheinwerk Verlag,
    Titel: HTML und CSS : das umfassende Handbuch
    Autor: Wolf, Jürgen
    Ausgabe: 4., aktualisierte und überarbeitete Auflage
    Verlag: Bonn :Rheinwerk Verlag,
    Erscheinungsjahr: 2021
    Seiten: 1158 Seiten
    ISBN: 978-3-8362-8117-1
    Materialart: Buch
    Sprache: Deutsch
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  • 139
    Titel: Forschungsdatenmanagement und Recht : Datenschutz-, Urheber- und Vertragsrecht
    Autor: Baumann, Paul
    Beteiligte Person(en): Krahn, Philipp , Lauber-Rönsberg, Anne
    Verlag: Feldkirch/Düns :Neugebauer,
    Erscheinungsjahr: 2021
    Seiten: 304 Seiten
    ISBN: 978-3-85376-328-5
    Materialart: Buch
    Sprache: Deutsch
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  • 140
    Buch
    Buch
    Cambridge :Cambridge University Press,
    Titel: ¬The¬ science of science /
    Autor: Wang, Dashun
    Beteiligte Person(en): Barabási, Albert-László
    Verlag: Cambridge :Cambridge University Press,
    Erscheinungsjahr: 2021
    Seiten: x, 303 Seiten
    ISBN: 978-1-108-71695-6
    Materialart: Buch
    Sprache: Englisch
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  • 141
    Buch
    Buch
    Basel :Springer International Publishing,
    Titel: Introduction to Quantum Computing /
    Autor: LaPierre, Ray
    Verlag: Basel :Springer International Publishing,
    Erscheinungsjahr: 2021
    Seiten: 368 Seiten
    ISBN: 978-3-030-69317-6
    Materialart: Buch
    Sprache: Englisch
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  • 142
    Titel: Handbuch Prüfung ortsfester elektrischer Anlagen und Betriebsmittel : Prüfabläufe, Grenz- und Richtwerte gem. DIN VDE 0100-600 und 0105-100 für die Prüfung vor Ort
    Autor: Donath, Karl [Verfasser]
    Beteiligte Person(en): Rottmann, Rainer [Verfasser] , Orgel, Christian [Verfasser]
    Ausgabe: 4. überarbeitete Auflage
    Verlag: Forum Verlag Herkert,
    Erscheinungsjahr: 2021
    Seiten: 374 Seiten
    Materialart: Buch
    Sprache: Deutsch
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  • 143
    Titel: Handbuch Prüfung ortsveränderlicher elektrischer Geräte : Prüfabläufe, Grenz- und Richtwerte gem. DIN VDE 0701-0702 für die Prüfung vor Ort
    Beteiligte Person(en): Donath, Karl [Verfasser] , Rottmann, Rainer [Verfasser] , Gavrancic, Milan [Verfasser] , Orgel, Christian [Verfasser]
    Ausgabe: 4. überarbeitete Auflage
    Verlag: Forum Verlag Herkert,
    Erscheinungsjahr: 2021
    Seiten: 311 Seiten
    ISBN: 978-3-96314-615-2
    Materialart: Buch
    Sprache: Deutsch
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  • 144
    Titel: Docker : das Praxisbuch für Entwickler und DevOps-Teams
    Autor: Öggl, Bernd
    Beteiligte Person(en): Kofler, Michael
    Ausgabe: 3. Aufl.
    Erscheinungsjahr: 2021
    Seiten: 496 S. : , Illustrationen, Diagramme
    ISBN: 978-3-8362-8634-3
    Materialart: Buch
    Sprache: Deutsch
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  • 145
    Titel: Götzendämmerung : Kunst und Künstliche Intelligenz
    Beteiligte Person(en): Dotzler, Bernhard J. , Karpat, Berkan
    Verlag: Bielefeld :transcript,
    Erscheinungsjahr: 2021
    Seiten: 154 Seiten
    ISBN: 978-3-8376-5976-4
    Materialart: Buch
    Sprache: Deutsch
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  • 146
    Buch
    Buch
    München :C.H. Beck,
    Titel: Muster : Theorie der digitalen Gesellschaft
    Autor: Nassehi, Armin
    Ausgabe: 1. Auflage
    Verlag: München :C.H. Beck,
    Erscheinungsjahr: 2021
    Seiten: 352 Seiten
    ISBN: 978-3-406-76786-9
    Materialart: Buch
    Sprache: Deutsch
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  • 147
    Buch
    Buch
    München :Verlag Franz Vahlen GmbH,
    Titel: Liberating structures : Entscheidungsfindung revolutionieren
    Autor: Steinhöfer, Daniel
    Verlag: München :Verlag Franz Vahlen GmbH,
    Erscheinungsjahr: 2021
    Seiten: 120 Seiten
    ISBN: 978-3-8006-5929-6
    Materialart: Buch
    Sprache: Deutsch
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  • 148
    Titel: Crashkurs Internes Kontrollsystem für Buchhaltung und Steuern /
    Autor: Alves, Winfried
    Ausgabe: 2. völlig überarbeitete und erweiterte Auflage
    Erscheinungsjahr: 2021
    Seiten: 167 Seiten
    ISBN: 978-3-648-14049-9
    Materialart: Buch
    Sprache: Deutsch
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  • 149
    Publikationsdatum: 2023-01-06
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 150
    Publikationsdatum: 2023-01-06
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 151
    Publikationsdatum: 2023-02-03
    Beschreibung: This is the documentation on current results of a research project jointly conducted by Stiftung Deutsche Kinemathek (SDK) and Zuse Institute Berlin (ZIB). In this project, we are working on a practical yet sustainable archiving solution for audiovisual material. In the course of the project two major obstacles were identified: 1) Metadata is collected according to standards established in the community but lacking a prescribed serialisation format. 2) Storage size of audiovisual material and time scales of production processes make it often impractical to defer submission for archival storage until all components have arrived and can be processed in one go.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 152
    Publikationsdatum: 2023-02-03
    Beschreibung: Kunst- und Kulturinstitutionen beschäftigen sich zunehmend mit der Digitalisierung ihrer Sammlungen, auch und gerade im Angesicht der Pandemie 2020. Dabei spielen nicht nur technische und organisatorische Fragen eine Rolle, vor allem rechtliche Aspekte führen oft zu Unsicherheit bei der digitalen Zugänglichmachung der Daten. Um diesen Unsicherheiten kompakt zu begegnen, gibt digiS die "Rechtsfibel" in Zusammenarbeit mit iRights und Paul Klimpel als Autor heraus. Darin werden unter anderem konkrete Fragen des Urheberrechts zu verschiedenen Objektgattungen, Lizenzfragen, Persönlichkeitsrecht und Datenschutz, die Online-Präsentation von Digitalisaten und zur Archivierung behandelt. Die Handreichung soll Mitarbeiter*innen in Kultur(-erbe)einrichtungen ermutigen, sich mit den rechtlichen Fragen bei der Digitalisierung auseinanderzusetzen, indem sie die vielen Facetten dieses Bereichs verständlich darstellt.
    Sprache: Deutsch
    Materialart: other , doc-type:Other
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  • 153
    Publikationsdatum: 2023-03-20
    Beschreibung: As the natural gas market is moving towards short-term planning, accurate and robust short-term forecasts of the demand and supply of natural gas is of fundamental importance for a stable energy supply, a natural gas control schedule, and transport operation on a daily basis. We propose a hybrid forecast model, Functional AutoRegressive and Convolutional Neural Network model, based on state-of-the-art statistical modeling and artificial neural networks. We conduct short-term forecasting of the hourly natural gas flows of 92 distribution nodes in the German high-pressure gas pipeline network, showing that the proposed model provides nice and stable accuracy for different types of nodes. It outperforms all the alternative models, with an improved relative accuracy up to twofold for plant nodes and up to fourfold for municipal nodes. For the border nodes with rather flat gas flows, it has an accuracy that is comparable to the best performing alternative model.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 154
    Publikationsdatum: 2023-03-20
    Beschreibung: The choice of solvents influences crystalline solid formed during the crystallization of active pharmaceutical ingredients (API). The underlying effects are not always well understood because of the complexity of the systems. Theoretical models are often insufficient to describe this phenomenon. In this study, the crystallization behavior of the model drug paracetamol in different solvents was studied based on experimental and molecular dynamics data. The crystallization process was followed in situ using time-resolved Raman spectroscopy. Molecular dynamics with simulated annealing algorithm was used for an atomistic understanding of the underlying processes. The experimental and theoretical data indicate that paracetamol molecules adopt a particular geometry in a given solvent predefining the crystallization of certain polymorphs.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 155
  • 156
    Publikationsdatum: 2023-03-31
    Beschreibung: We present an extension of Taylor's Theorem for the piecewise polynomial expansion of non-smooth evaluation procedures involving absolute value operations. Evaluation procedures are computer programs of mathematical functions in closed form expression and allow a different treatment of smooth operations or calls to the absolute value function. The well known classical Theorem of Taylor defines polynomial approximations of sufficiently smooth functions and is widely used for the derivation and analysis of numerical integrators for systems of ordinary differential- or differential-algebraic equations, for the construction of solvers for continuous non-linear optimization of finite dimensional objective functions and for root solving of non-linear systems of equations. The long term goal is the stabilization and acceleration of already known methods and the derivation of new methods by incorporating piecewise polynomial Taylor expansions. The herein provided proof of the higher order approximation quality of the new generalized expansions is constructive and allows efficiently designed algorithms for the execution and computation of the piecewise polynomial expansions. As a demonstration towards the ultimate goal we will derive a prototype of a {\$}{\$}k{\$}{\$}k-step method on the basis of polynomial interpolation and the proposed generalized expansions.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 157
    Publikationsdatum: 2023-03-31
    Beschreibung: Tom Streubel has observed that for functions in abs-normal form, generalized Taylor expansions of arbitrary order $\bar d-1$ can be generated by algorithmic piecewise differentiation. Abs-normal form means that the real or vector valued function is defined by an evaluation procedure that involves the absolute value function $|...|$ apart from arithmetic operations and $\bar d$ times continuously differentiable univariate intrinsic functions. The additive terms in Streubel's expansion are abs-polynomial, i.e. involve neither divisions nor intrinsics. When and where no absolute values occur, Moore's recurrences can be used to propagate univariate Taylor polynomials through the evaluation procedure with a computational effort of $\mathcal O({\bar d}^2)$, provided all univariate intrinsics are defined as solutions of linear ODEs. This regularity assumption holds for all standard intrinsics, but for irregular elementaries one has to resort to Faa di Bruno's formula, which has exponential complexity in $\bar d$. As already conjectured we show that the Moore recurrences can be adapted for regular intrinsics to the abs-normal case. Finally, we observe that where the intrinsics are real analytic the expansions can be extended to infinite series that converge absolutely on spherical domains.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 158
    Publikationsdatum: 2023-03-31
    Beschreibung: Tom Streubel has observed that for functions in abs-normal form, generalized Taylor expansions of arbitrary order $\bar d-1$ can be generated by algorithmic piecewise differentiation. Abs-normal form means that the real or vector valued function is defined by an evaluation procedure that involves the absolute value function $|...|$ apart from arithmetic operations and $\bar d$ times continuously differentiable univariate intrinsic functions. The additive terms in Streubel's expansion are abs-polynomial, i.e. involve neither divisions nor intrinsics. When and where no absolute values occur, Moore's recurrences can be used to propagate univariate Taylor polynomials through the evaluation procedure with a computational effort of $\mathcal O({\bar d}^2)$, provided all univariate intrinsics are defined as solutions of linear ODEs. This regularity assumption holds for all standard intrinsics, but for irregular elementaries one has to resort to Faa di Bruno's formula, which has exponential complexity in $\bar d$. As already conjectured we show that the Moore recurrences can be adapted for regular intrinsics to the abs-normal case. Finally, we observe that where the intrinsics are real analytic the expansions can be extended to infinite series that converge absolutely on spherical domains.
    Sprache: Englisch
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  • 159
    Publikationsdatum: 2023-04-14
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 160
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2023-04-17
    Beschreibung: 混合整数計画法 (Mixed Integer Programming: MIP) は,MIP を解くソフトウェアである MIP ソルバが大規模な現実問題を解けるようになったこともあり,現実問題を解く有用な OR の手法として広く知られるようになった.しかしながら,MIP ソルバの開発に欠かせないベンチマーク・データセットおよび性能測定方法についてはそれほど広く知られているとは言い難い.ベンチマーク・データセットは注意を払って作成しないと,多くのバイアスがかかってしまう.それらのバイアスを可能な限りのぞき,真に有用なベンチマーク・テストの結果を得るためには複数の人数で多大な労力を割く必要がある.本稿では,そのような MIP ソルバ開発の背景として重要な役割を果たしてきた MIPLIB と Hans Mittelmann’s benchmarks について解説する.また,本稿において Hans Mittelmann’s benchmarks は,BENCHMARKS FOR OPTIMIZATION SOFTWAREのページ (http://plato.asu.edu/bench.html) に示されているベンチマークである.
    Sprache: Japanisch
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  • 161
    Publikationsdatum: 2023-04-19
    Beschreibung: We present a transductive learning approach for morphometric osteophyte grading based on geometric deep learning. We formulate the grading task as semi-supervised node classification problem on a graph embedded in shape space. To account for the high-dimensionality and non-Euclidean structure of shape space we employ a combination of an intrinsic dimension reduction together with a graph convolutional neural network. We demonstrate the performance of our derived classifier in comparisons to an alternative extrinsic approach.
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 162
    Publikationsdatum: 2023-07-14
    Beschreibung: A decision support system relies on frequent re-solving of similar problem instances. While the general structure remains the same in corresponding applications, the input parameters are updated on a regular basis. We propose a generative neural network design for learning integer decision variables of mixed-integer linear programming (MILP) formulations of these problems. We utilise a deep neural network discriminator and a MILP solver as our oracle to train our generative neural network. In this article, we present the results of our design applied to the transient gas optimisation problem. With the trained network we produce a feasible solution in 2.5s, use it as a warm-start solution, and thereby decrease global optimal solution solve time by 60.5%.
    Sprache: Englisch
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  • 163
    Publikationsdatum: 2023-07-17
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 164
    Publikationsdatum: 2023-07-17
    Beschreibung: In order to better understand the relationship between shape of the nasal cavity and to find objective classification for breathing obstruction, a population of 25 cases of healthy nasal cavity and 27 cases with diagnosed nasal airway obstruction (NAO) was examined for correlations between morphological, clinical and CFD parameters. For this purpose a workflow was implemented in Tcl to perform automatic measurements of morphological parameters of nasal cavity surfaces in Amira, which has as output a table with all estimated values. Furthermore, the statistical analysis was designed using Python to find the most probable subset of parameters that are predictors of nasal cavity pathology and consisted of correlation analysis, the selection of the best possible subset of parameters that could be used as predictors of clinically stated pathology of the nasal cavity by a logistic regression classifier. As a result, 10 most promising parameters were identified: mean distance between the two isthmuses, left isthmus contour, area ratio between the two isthmuses, left isthmus height, height ratio between the two isthmuses, left isthmus width, right isthmus width, right isthmus hydraulic diameter, mean distance of septal curvature between the septum enclosing walls of the nasal cavity, velocities volume average by expiration. As it turns out, most parameters refer to the isthmus region. This was to be expected since this region plays an important role in the airflow system of the nasal cavity.
    Sprache: Englisch
    Materialart: bachelorthesis , doc-type:bachelorThesis
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  • 165
    Publikationsdatum: 2023-07-17
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 166
    Publikationsdatum: 2023-07-17
    Beschreibung: The growing importance of mathematical software in everyday life—in applications such as internet communication, traffic, and artificial intelligence—necessitates advances in software documentation services to raise awareness of existing packages and their usage. Such information helps potential software developers and users make informed choices about packages that could advance their work in modeling, simulation, and analysis. At the same time, software presents novel challenges to information services that require the development of new methods and means of processing. swMATH provides users with an overview of a broad range of mathematical software and extends documentation services for publications related to such software. It acts as a counterpart to the established abstracting and reviewing services for mathematical publications and has nearly 30,000 entries, making it one of the most comprehensive documentation services in mathematics.
    Sprache: Englisch
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  • 167
    Publikationsdatum: 2023-07-17
    Beschreibung: More and more diseases have been found to be strongly correlated with disturbances in the microbiome constitution, e.g., obesity, diabetes, or some cancer types. Thanks to modern high-throughput omics technologies, it becomes possible to directly analyze human microbiome and its influence on the health status. Microbial communities are monitored over long periods of time and the associations between their members are explored. These relationships can be described by a time-evolving graph. In order to understand responses of the microbial community members to a distinct range of perturbations such as antibiotics exposure or diseases and general dynamical properties, the time-evolving graph of the human microbial communities has to be analyzed. This becomes especially challenging due to dozens of complex interactions among microbes and metastable dynamics. The key to solving this problem is the representation of the time-evolving graphs as fixed-length feature vectors preserving the original dynamics. We propose a method for learning the embedding of the time-evolving graph that is based on the spectral analysis of transfer operators and graph kernels. We demonstrate that our method can capture temporary changes in the time-evolving graph on both synthetic data and real-world data. Our experiments demonstrate the efficacy of the method. Furthermore, we show that our method can be applied to human microbiome data to study dynamic processes.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 168
    Publikationsdatum: 2023-08-02
    Beschreibung: Urban transportation systems are subject to a high level of variation and fluctuation in demand over the day. When this variation and fluctuation are observed in both time and space, it is crucial to develop line plans that are responsive to demand. A multi-period line planning approach that considers a changing demand during the planning horizon is proposed. If such systems are also subject to limitations of resources, a dynamic transfer of resources from one line to another throughout the planning horizon should also be considered. A mathematical modelling framework is developed to solve the line planning problem with a cost-oriented approach considering transfer of resources during a finite length planning horizon of multiple periods. We use real-life public transportation network data for our computational results. We analyze whether or not multi-period solutions outperform single period solutions in terms of feasibility and relevant costs. The importance of demand variation on multi-period solutions is investigated. We evaluate the impact of resource transfer constraints on the effectiveness of solutions. We also study the effect of period lengths along with the problem parameters that are significant for and sensitive to the optimality of solutions.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 169
    Publikationsdatum: 2023-08-02
    Beschreibung: Public transportation networks are typically operated with a periodic timetable. The Periodic Event Scheduling Problem (PESP) is the standard mathematical modelling tool for periodic timetabling. Since PESP can be solved in linear time on trees, it is a natural question to ask whether there are polynomial-time algorithms for input networks of bounded treewidth. We show that deciding the feasibility of a PESP instance is NP-hard even when the treewidth is 2, the branchwidth is 2, or the carvingwidth is 3. Analogous results hold for the optimization of reduced PESP instances, where the feasibility problem is trivial. To complete the picture, we present two pseudo-polynomial-time dynamic programming algorithms solving PESP on input networks with bounded tree- or branchwidth. We further analyze the parameterized complexity of PESP with bounded cyclomatic number, diameter, or vertex cover number. For event-activity networks with a special -- but standard -- structure, we give explicit and sharp bounds on the branchwidth in terms of the maximum degree and the carvingwidth of an underlying line network. Finally, we investigate several parameters on the smallest instance of the benchmarking library PESPlib.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 170
    Publikationsdatum: 2023-08-02
    Beschreibung: Conformational dynamics is essential to biomolecular processes. Markov State Models (MSMs) are widely used to elucidate dynamic properties of molecular systems from unbiased Molecular Dynamics (MD). However, the implementation of reweighting schemes for MSMs to analyze biased simulations is still at an early stage of development. Several dynamical reweighing approaches have been proposed, which can be classified as approaches based on (i) Kramers rate theory, (ii) rescaling of the probability density flux, (iii) reweighting by formulating a likelihood function, (iv) path reweighting. We present the state-of-the-art and discuss the methodological differences of these methods, their limitations and recent applications.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 171
    Publikationsdatum: 2023-08-04
    Beschreibung: Phage display biopanning with Illumina next-generation sequencing (NGS) is applied to reveal insights into peptide-based adhesion domains for polypropylene (PP). One biopanning round followed by NGS selects robust PP-binding peptides that are not evident by Sanger sequencing. NGS provides a significant statistical base that enables motif analysis, statistics on positional residue depletion/enrichment, and data analysis to suppress false-positive sequences from amplification bias. The selected sequences are employed as water-based primers for PP?metal adhesion to condition PP surfaces and increase adhesive strength by 100\% relative to nonprimed PP.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 172
    Publikationsdatum: 2023-08-24
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 173
    Publikationsdatum: 2023-10-02
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 174
    Publikationsdatum: 2023-11-03
    Beschreibung: The temporally and spatially resolved tracking of lithium intercalation and electrode degradation processes are crucial for detecting and understanding performance losses during the operation of lithium-batteries. Here, high-throughput X-ray computed tomography has enabled the identification of mechanical degradation processes in a commercial Li/MnO2 primary battery and the indirect tracking of lithium diffusion; furthermore, complementary neutron computed tomography has identified the direct lithium diffusion process and the electrode wetting by the electrolyte. Virtual electrode unrolling techniques provide a deeper view inside the electrode layers and are used to detect minor fluctuations which are difficult to observe using conventional three dimensional rendering tools. Moreover, the ‘unrolling’ provides a platform for correlating multi-modal image data which is expected to find wider application in battery science and engineering to study diverse effects e.g. electrode degradation or lithium diffusion blocking during battery cycling.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 175
    Publikationsdatum: 2023-11-03
    Beschreibung: On average, an approved drug today costs $2-3 billion and takes over ten years to develop1. In part, this is due to expensive and time-consuming wet-lab experiments, poor initial hit compounds, and the high attrition rates in the (pre-)clinical phases. Structure-based virtual screening (SBVS) has the potential to mitigate these problems. With SBVS, the quality of the hits improves with the number of compounds screened2. However, despite the fact that large compound databases exist, the ability to carry out large-scale SBVSs on computer clusters in an accessible, efficient, and flexible manner has remained elusive. Here we designed VirtualFlow, a highly automated and versatile open-source platform with perfect scaling behaviour that is able to prepare and efficiently screen ultra-large ligand libraries of compounds. VirtualFlow is able to use a variety of the most powerful docking programs. Using VirtualFlow, we have prepared the largest and freely available ready-to-dock ligand library available, with over 1.4 billion commercially available molecules. To demonstrate the power of VirtualFlow, we screened over 1 billion compounds and discovered a small molecule inhibitor (iKeap1) that engages KEAP1 with nanomolar affinity (Kd = 114 nM) and disrupts the interaction between KEAP1 and the transcription factor NRF2. We also identified a set of structurally diverse molecules that bind to KEAP1 with submicromolar affinity. This illustrates the potential of VirtualFlow to access vast regions of the chemical space and identify binders with high affinity for target proteins.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 176
    Publikationsdatum: 2023-11-03
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 177
    Publikationsdatum: 2023-11-03
    Beschreibung: Fast domain propagation of linear constraints has become a crucial component of today's best algorithms and solvers for mixed integer programming and pseudo-boolean optimization to achieve peak solving performance. Irregularities in the form of dynamic algorithmic behaviour, dependency structures, and sparsity patterns in the input data make efficient implementations of domain propagation on GPUs and, more generally, on parallel architectures challenging. This is one of the main reasons why domain propagation in state-of-the-art solvers is single thread only. In this paper, we present a new algorithm for domain propagation which (a) avoids these problems and allows for an efficient implementation on GPUs, and is (b) capable of running propagation rounds entirely on the GPU, without any need for synchronization or communication with the CPU. We present extensive computational results which demonstrate the effectiveness of our approach and show that ample speedups are possible on practically relevant problems: on state-of-the-art GPUs, our geometric mean speed-up for reasonably-large instances is around 10x to 20x and can be as high as 195x on favorably-large instances.
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 178
    Publikationsdatum: 2023-11-03
    Beschreibung: Structure-based virtual screening approaches have the ability to dramatically reduce the time and costs associated to the discovery of new drug candidates. Studies have shown that the true hit rate of virtual screenings improves with the scale of the screened ligand libraries. Therefore, we have recently developed an open source drug discovery platform (VirtualFlow), which is able to routinely carry out ultra-large virtual screenings. One of the primary challenges of molecular docking is the circumstance when the protein is highly dynamic or when the structure of the protein cannot be captured by a static pose. To accommodate protein dynamics, we report the extension of VirtualFlow to allow the docking of ligands using a grey wolf optimization algorithm using the docking program GWOVina, which substantially improves the quality and efficiency of flexible receptor docking compared to AutoDock Vina. We demonstrate the linear scaling behavior of VirtualFlow utilizing GWOVina up to 128 000 CPUs. The newly supported docking method will be valuable for drug discovery projects in which protein dynamics and flexibility play a significant role.
    Sprache: Englisch
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  • 179
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2023-11-03
    Beschreibung: The determination of time of death is one of the central tasks in forensic medicine. A standard method of time of death estimation elies on matching temperature measurements of the corpse with a post-mortem cooling model. In addition to widely used empirical post-mortem models, modelling based on a precise mathematical simulation of the cooling process have been gaining popularity. The simulation based cooling models and the resulting time of death estimates dependon a large variety of parameters. These include hermal properties for different body tissue types, environmental conditions such as temperature and air flow, and the presence of clothing and coverings. In this thesis we focus on a specific arameter - the contact between corpse and underground - and investigate its influence on the time of death estimation. Resulting we aim to answer the question whether it is necessary to consider contact mechanics in the underlying mathematical cooling model.
    Sprache: Englisch
    Materialart: masterthesis , doc-type:masterThesis
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  • 180
    Publikationsdatum: 2023-11-03
    Beschreibung: Though gait asymmetry is used as a metric of functional recovery in clinical rehabilitation, there is no consensus on an ideal method for its evaluation. Various methods have been proposed but are limited in scope, as they can often use only positive signals or discrete values extracted from time-scale data as input. By defining five symmetry axioms, a framework for benchmarking existing methods was established and a new method was described here for the first time: the weighted universal symmetry index (wUSI), which overcomes limitations of other methods. Both existing methods and the wUSI were mathematically compared to each other and in respect to their ability to fulfill the proposed symmetry axioms. Eligible methods that fulfilled these axioms were then applied using both discrete and continuous approaches to ground reaction force (GRF) data collected from healthy gait, both with and without artificially induced asymmetry using a single instrumented elbow crutch. The wUSI with a continuous approach was the only symmetry method capable of determining GRF asymmetries in different walking conditions in all three planes of motion. When used with a continuous approach, the wUSI method was able to detect asymmetries while avoiding artificial inflation, a common problem reported in other methods. In conclusion, the wUSI is proposed as a universal method to quantify three-dimensional GRF asymmetries, which may also be expanded to other biomechanical signals.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 181
    Publikationsdatum: 2023-11-03
    Beschreibung: In state-of-the-art mixed-integer programming solvers, a large array of reduction techniques are applied to simplify the problem and strengthen the model formulation before starting the actual branch-and-cut phase. Despite their mathematical simplicity, these methods can have significant impact on the solvability of a given problem. However, a crucial property for employing presolve techniques successfully is their speed. Hence, most methods inspect constraints or variables individually in order to guarantee linear complexity. In this paper, we present new hashing-based pairing mechanisms that help to overcome known performance limitations of more powerful presolve techniques that consider pairs of rows or columns. Additionally, we develop an enhancement to one of these presolve techniques by exploiting the presence of set-packing structures on binary variables in order to strengthen the resulting reductions without increasing runtime. We analyze the impact of these methods on the MIPLIB 2017 benchmark set based on an implementation in the MIP solver SCIP.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 182
    Publikationsdatum: 2023-11-03
    Beschreibung: In this paper, we introduce the Maximum Diversity Assortment Selection Problem (MADASS), which is a generalization of the 2-dimensional Cutting Stock Problem (2CSP). Given a set of rectangles and a rectangular container, the goal of 2CSP is to determine a subset of rectangles that can be placed in the container without overlapping, i.e., a feasible assortment, such that a maximum area is covered. In MADASS, we need to determine a set of feasible assortments, each of them covering a certain minimum threshold of the container, such that the diversity among them is maximized. Thereby, diversity is defined as minimum or average normalized Hamming-Distance of all assortment pairs. The MADASS Problem was used in the 11th AIMMS-MOPTA Competition in 2019. The methods we describe in this article and the computational results won the contest. In the following, we give a definition of the problem, introduce a mathematical model and solution approaches, determine upper bounds on the diversity, and conclude with computational experiments conducted on test instances derived from the 2CSP literature.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 183
    Publikationsdatum: 2023-11-03
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 184
    Publikationsdatum: 2023-11-06
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 185
    Publikationsdatum: 2023-11-06
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 186
    Publikationsdatum: 2023-11-06
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 187
    Publikationsdatum: 2023-11-06
    Sprache: Englisch
    Materialart: book , doc-type:book
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  • 188
    Publikationsdatum: 2023-11-06
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 189
    Publikationsdatum: 2023-11-06
    Beschreibung: We present visual methods for the analysis and comparison of the results of curved fibre reconstruction algorithms, i.e., of algorithms extracting characteristics of curved fibres from X-ray computed tomography scans. In this work, we extend previous methods for the analysis and comparison of results of different fibre reconstruction algorithms or parametrisations to the analysis of curved fibres. We propose fibre dissimilarity measures for such curved fibres and apply these to compare multiple results to a specified reference. We further propose visualisation methods to analyse differences between multiple results quantitatively and qualitatively. In two case studies, we show that the presented methods provide valuable insights for advancing and parametrising fibre reconstruction algorithms, and support in improving their results in characterising curved fibres.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 190
    Publikationsdatum: 2023-11-06
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 191
    Publikationsdatum: 2024-01-12
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 192
    Publikationsdatum: 2024-01-12
    Beschreibung: Two essential ingredients of modern mixed-integer programming (MIP) solvers are diving heuristics that simulate a partial depth-first search in a branch-and-bound search tree and conflict analysis of infeasible subproblems to learn valid constraints. So far, these techniques have mostly been studied independently: primal heuristics under the aspect of finding high-quality feasible solutions early during the solving process and conflict analysis for fathoming nodes of the search tree and improving the dual bound. Here, we combine both concepts in two different ways. First, we develop a diving heuristic that targets the generation of valid conflict constraints from the Farkas dual. We show that in the primal this is equivalent to the optimistic strategy of diving towards the best bound with respect to the objective function. Secondly, we use information derived from conflict analysis to enhance the search of a diving heuristic akin to classical coefficient diving. The computational performance of both methods is evaluated using an implementation in the source-open MIP solver SCIP. Experiments are carried out on publicly available test sets including Miplib 2010 and Cor@l.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 193
    Publikationsdatum: 2024-01-12
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 194
    Publikationsdatum: 2024-01-12
    Beschreibung: Conflict learning plays an important role in solving mixed integer programs (MIPs) and is implemented in most major MIP solvers. A major step for MIP conflict learning is to aggregate the LP relaxation of an infeasible subproblem to a single globally valid constraint, the dual proof, that proves infeasibility within the local bounds. Among others, one way of learning is to add these constraints to the problem formulation for the remainder of the search. We suggest to not restrict this procedure to infeasible subproblems, but to also use global proof constraints from subproblems that are not (yet) infeasible, but can be expected to be pruned soon. As a special case, we also consider learning from integer feasible LP solutions. First experiments of this conflict-free learning strategy show promising results on the MIPLIB2017 benchmark set.
    Sprache: Englisch
    Materialart: conferenceobject , doc-type:conferenceObject
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  • 195
    Publikationsdatum: 2024-01-12
    Beschreibung: The SCIP Optimization Suite provides a collection of software packages for mathematical optimization centered around the constraint integer programming frame- work SCIP. This paper discusses enhancements and extensions contained in version 7.0 of the SCIP Optimization Suite. The new version features the parallel presolving library PaPILO as a new addition to the suite. PaPILO 1.0 simplifies mixed-integer linear op- timization problems and can be used stand-alone or integrated into SCIP via a presolver plugin. SCIP 7.0 provides additional support for decomposition algorithms. Besides im- provements in the Benders’ decomposition solver of SCIP, user-defined decomposition structures can be read, which are used by the automated Benders’ decomposition solver and two primal heuristics. Additionally, SCIP 7.0 comes with a tree size estimation that is used to predict the completion of the overall solving process and potentially trigger restarts. Moreover, substantial performance improvements of the MIP core were achieved by new developments in presolving, primal heuristics, branching rules, conflict analysis, and symmetry handling. Last, not least, the report presents updates to other components and extensions of the SCIP Optimization Suite, in particular, the LP solver SoPlex and the mixed-integer semidefinite programming solver SCIP-SDP.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 196
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2024-01-12
    Beschreibung: The generalization of MIP techniques to deal with nonlinear, potentially non-convex, constraints have been a fruitful direction of research for computational MINLP in the last decade. In this paper, we follow that path in order to extend another essential subroutine of modern MIP solvers towards the case of nonlinear optimization: the analysis of infeasible subproblems for learning additional valid constraints. To this end, we derive two different strategies, geared towards two different solution approaches. These are using local dual proofs of infeasibility for LP-based branch-and-bound and the creation of nonlinear dual proofs for NLP-based branch-and-bound, respectively. We discuss implementation details of both approaches and present an extensive computational study, showing that both techniques can significantly enhance performance when solving MINLPs to global optimality.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 197
    Publikationsdatum: 2024-01-12
    Beschreibung: We propose a hybrid discrete-continuous algorithm for flight planning in free flight airspaces. In a first step, our DisCOptER method discrete-continuous optimization for enhanced resolution) computes a globally optimal approximate flight path on a discretization of the problem using the A* method. This route initializes a Newton method that converges rapidly to the smooth optimum in a second step. The correctness, accuracy, and complexity of the method are goverened by the choice of the crossover point that determines the coarseness of the discretization. We analyze the optimal choice of the crossover point and demonstrate the asymtotic superority of DisCOptER over a purely discrete approach.
    Sprache: Englisch
    Materialart: article , doc-type:article
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  • 198
    Publikationsdatum: 2024-01-12
    Beschreibung: We propose a hybrid discrete-continuous algorithm for flight planning in free flight airspaces. In a first step, our DisCOptER method discrete-continuous optimization for enhanced resolution) computes a globally optimal approximate flight path on a discretization of the problem using the A* method. This route initializes a Newton method that converges rapidly to the smooth optimum in a second step. The correctness, accuracy, and complexity of the method are goverened by the choice of the crossover point that determines the coarseness of the discretization. We analyze the optimal choice of the crossover point and demonstrate the asymtotic superority of DisCOptER over a purely discrete approach.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 199
    Publikationsdatum: 2024-01-12
    Beschreibung: Due to the increase in accessibility and robustness of sequencing technology, single cell RNA-seq (scRNA-seq) data has become abundant. The technology has made significant contributions to discovering novel phenotypes and heterogeneities of cells. Recently, there has been a push for using single-- or multiple scRNA-seq snapshots to infer the underlying gene regulatory networks (GRNs) steering the cells' biological functions. To date, this aspiration remains unrealised. In this paper, we took a bottom-up approach and curated a stochastic two gene interaction model capturing the dynamics of a complete system of genes, mRNAs, and proteins. In the model, the regulation was placed upstream from the mRNA on the gene level. We then inferred the underlying regulatory interactions from only the observation of the mRNA population through~time. We could detect signatures of the regulation by combining information of the mean, covariance, and the skewness of the mRNA counts through time. We also saw that reordering the observations using pseudo-time did not conserve the covariance and skewness of the true time course. The underlying GRN could be captured consistently when we fitted the moments up to degree three; however, this required a computationally expensive non-linear least squares minimisation solver. There are still major numerical challenges to overcome for inference of GRNs from scRNA-seq data. These challenges entail finding informative summary statistics of the data which capture the critical regulatory information. Furthermore, the statistics have to evolve linearly or piece-wise linearly through time to achieve computational feasibility and scalability.
    Sprache: Englisch
    Materialart: reportzib , doc-type:preprint
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  • 200
    Publikationsdatum: 2023-12-20
    Sprache: Englisch
    Materialart: article , doc-type:article
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