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An In-Out Approach to Disjunctive Optimization

An In-Out Approach to Disjunctive Optimization

7th international conference Integration of AI and OR Techniques in Constraint programming for Combinatorial Optimization Problems

作者： Fischetti, Matteo Salvagnin, Domenico Univ Padua DEI I-35100 Padua Italy Univ Padua dmpa Padua Italy

ISBN: (纸本)9783642135194

Cutting plane methods are widely used for solving convex optimization problems and are of fundamental importance, e.g., to provide tight bounds for Mixed-Integer Programs (MIPs). this is obtained by embedding a cut-separation module within a search scheme. the importance of a sound search scheme is well known in the Constraint programming (CP) community. Unfortunately, the "standard" search scheme typically used for MIP problems, known as the Kelley method, is often quite unsatisfactory because of saturation issues. In this paper we address the so-called Lift-and-Project closure for 0-1 MIPs associated with all disjunctive cuts generated from a given set of elementary disjunction. We focus on the search scheme embedding the generated cuts. In particular, we analyze a general meta-scheme for cutting plane algorithms, called in-out search, that was recently proposed by Ben-Ameur and Neto [1]. Computational results on test instances from the literature are presented, showing that using a more clever meta-scheme on top of a black-box cut generator may lead to a significant improvement.

关键词： Mixed-integer programming cutting planes disjunctive optimization

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Bonding in the "111" Type Ferropnictide Superconductor LiFeAs

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JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM 2010年第5期23卷 579-581页

作者： Li, Zhi Tse, J. S. Jin, C. Q. Chinese Acad Sci Inst Phys Beijing 100190 Peoples R China Univ Saskatchewan Dept Phys & Engn Phys Saskatoon SK S7N 5E2 Canada

Recently the electronic structure and magnetism of the "111" type LiFeAs superconductor has been investigated by first principles calculations based on the density functional theory. It is concluded that the system has a metallic striped anti-ferromagnetic ground state with a very small magnetic moment. Moreover, the effect of electronic correlation effect is also found to be weak. this finding is consistent with recent experiments and calculations on similar compounds. A strong covalent interaction has been suggested as a reason for the weak electron correlation. In this paper, the Fe As and Fe Fe interactions are examined from the analysis of the electronic localization function (ELF). Surprisingly, no strong evidence supporting Fe As and Fe Fe covalent bonding is found. A more delocalized electron distribution is observed in the Fe layers. therefore, the Fe 3d electrons are not as localized in the oxides and therefore the electron correlation effect is small. this is a plausible explanation for the apparent success of the local density approximation (LSDA) describing the weak magnetism in LiFeAs.

关键词： "111" type iron arsenide superconductors First principle calculations Itinerant magnetism

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Helping Biologists Effectively Build Workflows, without programming

Helping Biologists Effectively Build Workflows, without Prog...

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7th international conference on Data Integration in the Life Sciences

作者： Gordon, Paul M. K. Barker, Ken Sensen, Christoph W. Univ Calgary Dept Comp Sci 2500 Univ Dr NW Calgary AB T2N 1N4 Canada Univ Calgary Dept Biochem & Mol Biol Calgary AB T2N 4N1 Canada

ISBN: (纸本)9783642151194

Seahawk is a browser for Moby Web services, which are online tools using a shared semantic registry and data formats. To make a wider array of tools available within Seahawk, the Daggoo system helps users adapt forms on existing Web sites to Moby's specifications. Biologists were interviewed and given workflow design tasks, which revealed the types of tools present in their conceptual analysis workflows, and the types of control flow they understood. these observations were used to enhance Seahawk so that Moby and external Web tools can be browsed to create workflows "by demonstration". A flow-up user study measured how effectively biologists could 1) demonstrate a workflow for a realistic task, 2) understand the automatically generated workflow, and 3) use the workflow in the Taverna workflow editor/enactor. the results show promise that biologists without programming experience can become self-sufficient in analysis automation, using workflow-by-demonstration as a first step.

关键词： programming by demonstration bioinformatics workflows user study semantic web services

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A Constraint Integer programming Approach for Resource-Constrained Project Scheduling

A Constraint Integer Programming Approach for Resource-Const...

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7th international conference Integration of AI and OR Techniques in Constraint programming for Combinatorial Optimization Problems

作者： Berthold, Timo Heinz, Stefan Luebbecke, Marco E. Moehring, Rolf H. Schulz, Jens Zuse Inst Berlin Takustr 7 D-14195 Berlin Germany Tech Univ Darmstadt Fachbereich Math D-64293 Darmstadt Germany Tech Univ Berlin Math Inst D-10623 Berlin Germany

ISBN: (纸本)9783642135194

We propose a hybrid approach for solving the resource-constrained project scheduling problem which is an extremely hard to solve combinatorial optimization problem of practical relevance. Jobs have to be scheduled on (renewable) resources subject to precedence constraints such that the resource capacities are never exceeded and the latest completion time of all jobs is minimized. the problem has challenged researchers from different communities, such as integer programming (IP), constraint programming (CP), and satisfiability testing (SAT). Still, there are instances with 60 jobs which have not been solved for many years. the currently best known approach, LAZYFD, is a hybrid between CP and SAT techniques. In this paper we propose an even stronger hybridization by integrating all the three areas, IP, CP, and SAT, into a single branch-and-bound scheme. We show that lower bounds from the linear relaxation of the IP formulation and conflict analysis are key ingredients for pruning the search tree. First computational experiments show very promising results. For five instances of the well-known PSPLIB we report an improvement of lower bounds. Our implementation is generic, thus it can be potentially applied to similar problems as well.

关键词： Integer programming

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Memoization of methods using software transactional memory to track internal state dependencies 10

Memoization of methods using software transactional memory t...

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Proceedings of the 8th international conference on the Principles and Practice of programming in Java

作者： Rito, Hugo Cachopo, João INESC-ID Lisboa Technical University of Lisbon Portugal

ISBN: (纸本)9781450302692

Memoization is a well-known technique for improving the performance of a program, but it has been confined mostly to functional programming, where no mutable state or side-effects exist. Most object-oriented programs, however, are built around objects with an internal state that is mutable over the course of the program. therefore, the execution of methods often depends on the internal state of some objects or produces side-effects, thus making the application of memoization impractical for object-oriented programs in general. In this paper, we propose an extended memoization approach that builds on the support provided by a Software Transactional Memory (STM) to identify both internal state dependencies and side-effects, hence removing many of the limitations of traditional memoization. We describe the Automatic Transaction-Oriented Memoization (ATOM) system, a thread-safe implementation of our memoization model that requires minimal learning effort from programmers, while offering a simple and customizable interface. Additionally, we describe a memoization advisory system that collects per-method performance statistics with the ultimate goal of aiding programmers in their task of choosing which methods are profitable to memoize. We argue that ATOM is the first memoization system adequate to the unique characteristics of object-oriented programs and we show how memoization can be implemented almost for free in systems that use an STM, presenting the reasons why this synergy can be particularly useful in transactional contexts. We show the usefulness of memoizing object-oriented programs by applying memoization to the STMBench7 benchmark, a standard benchmark developed for evaluating STM> implementations. the memoized version of the benchmark shows up to a 14-fold increase in the throughput for a read-dominated workload. © 2010 ACM.

关键词： functional programming

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Basic VHDL tests conforming to IEC 61508

Basic VHDL tests conforming to IEC 61508

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international conference on Networked Sensing Systems

作者： Hayek, Ali Schreiber, Michael Borcsok, Josef Computer Architecture and System Programming University of Kassel 34121 Kassel Germany

ISBN: (纸本)9781424479108

the development of embedded sensing applications based on integrated circuits leads to ever-growing complexity of VHDL-code and requires sophisticated testability to achieve high diagnostic coverage. the norm IEC 61508 provides a set of requirements for the implementation of safety-related software. this paper deals with the testing of VHDL modules according to IEC 61508. Since VHDL is a hardware description language and differs from traditional software languages, new testing aspects and common coverage criteria are examined with respect to basic needs resulting from those differences. therefore, a development process according to the V-Model is introduced and a classification of VHDL modules is proposed, providing a basis on which several testing methods and exit-criteria can be evaluated with respect to specific design attributes common for each class. © 2010 IEEE.

关键词： Computer hardware description languages

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Multi-level topology-aware and multi-level parallelism on grid computing environments: A comparison of global arrays and OpenMP implementations

Multi-level topology-aware and multi-level parallelism on gr...

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7th Annual international conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON 2010

作者： Sirisup, Sirod U-Ruekolan, Suriya 112 Thailand Science Park Pahon Yothin Rd. Klong 1 Klong Luang Pathumthani 12120 Thailand

ISBN: (纸本)9789746724913

the Global Arrays toolkit is a library that allows programmers to write parallel programs that use large arrays distributed across processing nodes through the Aggregate Remote Memory Copy Interface (ARMCI). OpenMP is an application programming interface that supports shared memory multiprocessing on many architectures and platforms. In the Symmetric-Multi Processors (SMP), the Global Arrays toolkit will expose the programmers quite similar to that provided by OpenMP. In this study, we will further our investigation on the performance of a parallel application implemented with the Global Arrays toolkit and OpenMP on Grid computing environment. the investigation focuses on the case that an SMP cluster is included in the Grid computing environment. the multi-level parallelism together with multi-level topology-aware techniques have been used in both implementations. We have found that performance of the evaluating application implemented with Global Arrays technique is comparable to that of the application implemented with OpenMP. this implies that programmer can directly port the Global Arrays application directly to the SMP cluster yet its performance is not dropped compared to the native implementation.

关键词： Application programming interfaces (API)

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Security-constrained unit commitment using mixed-integer programming with Benders Decomposition

Security-constrained unit commitment using mixed-integer pro...

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7th Annual international conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON 2010

作者： Laothumyingyong, Nalan Damrongkulkamjorn, Parnjit Department of Electrical Engineering Faculty of Engineering Kasetsart University Bangkok Thailand

ISBN: (纸本)9789746724913

the objective of this paper is to determine the 24-hour unit commitment with minimum total generation cost subjecting to power flow constraints in both normal operating state and contingency state, which is considered the security-constrained unit commitment (SCUC). In this paper, the Benders' Decomposition technique has been applied by decomposing the problem into two parts: the master problem;and the sub-problems. the master problem which is the unit commitment problem contains integer variables as the on-off status of the generating units, and therefore could be solved as Mixed-Integer programming problem. the branch-and-cut method has been chosen to solve the master mixed-integer problem. there are two subproblems considered in this research: the power flow mismatch equations;and the operating limits of power systems. If the conditions in any subproblems are violated, the Benders Cuts corresponding to the violated constraints are added to the master problem and the mixed-integer unit commitment problem could be resolved. the proposed algorithm is tested on the IEEE 57-bus system with 7 thermal generating units. the 24-hour load data is made available along with the additional data for generating units. the results of typical unit commitment, security-constrained unit commitment under normal operating states and SCUC with contingency states are compared. the results show that the total generating costs of SCUC with contingency are higher than the others. However the committed units of that SCUC ensure that the system could still serve load when contingency occurs.

关键词： Integer programming

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Hybrid Parallel programming with MPI and Unified Parallel C 10

Hybrid Parallel Programming with MPI and Unified Parallel C

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7th ACM international conference on Computing Frontiers (CF)

作者： Dinan, James Balaji, Pavan Lusk, Ewing Sadayappan, P. thakur, Rajeev Ohio State Univ Dept Comp Sci & Engn 2015 Neil Ave Columbus OH 43210 USA Argonne Natl Lab Div Math & Comp Sci Argonne IL 60439 USA

ISBN: (纸本)9781450300445

the Message Passing Interface (MPI) is one of the most widely used programming models for parallel computing. However, the amount of memory available to an MPI process is limited by the amount of local memory within a compute node. Partitioned Global Address Space (PGAS) models such as Unified Parallel C (UPC) are growing in popularity because of their ability to provide a shared global address space that spans the memories of multiple compute nodes. However, taking advantage of UPC can require a large recoding effort for existing parallel applications. In this paper, we explore a new hybrid parallel programming model that combines MPI and UPC. this model allows MPI programmers incremental access to a greater amount of memory, enabling memory-constrained MPI codes to process larger data sets. In addition, the hybrid model offers UPC programmers an opportunity to create static UPC groups that are connected overMPI. As we demonstrate, the use of such groups can significantly improve the scalability of locality-constrained UPC codes. this paper presents a detailed description of the hybrid model and demonstrates its effectiveness in two applications: a random access benchmark and the Barnes-Hut cosmological simulation. Experimental results indicate that the hybrid model can greatly enhance performance;using hybrid UPC groups that span two cluster nodes, RA performance increases by a factor of 1.33 and using groups that span four cluster nodes, Barnes-Hut experiences a twofold speedup at the expense of a 2% increase in code size.

关键词： MPI UPC PGAS Hybrid Parallel programming

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Studies of productivity growth Index on the China's Yangtze River Delta cities

Studies of productivity growth Index on the China's Yangtze ...

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international conference on Services Systems and Services Management, ICSSSM

作者： Lan Xu Business School East China University of Science and Technology Shanghai China

this paper sets up a Malmquist Productivity Index system of economic growth to study the comprehensive capacities and important economic indicators for the 16 cities in the Yangtze River Delta Region. In the progress, it makes use of the Two-Stage Linear programming techniques to estimate the distance functions in reflection of the regional economic frontier. Further, the paper analyzes productivity growth because of the scale effect and technical progress which cause the internal differences to move on the different levels. the paper concludes to provide strategic suggestions with the collaborations, mutual activities, and functional division for each city in the delta region.

关键词： Productivity Rivers Cities and towns Economic indicators Linear programming Production Cause effect analysis Collaboration Industrial economics Manufacturing industries

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