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Approximating Two-Stage Chance-Constrained Programs with Classical Probability Bounds

Optimization Letters

Singh, Bismark; Watson, Jean-Paul

We consider a joint-chance constraint (JCC) as a union of sets, and approximate this union using bounds from classical probability theory. When these bounds are used in an optimization model constrained by the JCC, we obtain corresponding upper and lower bounds on the optimal objective function value. We compare the strength of these bounds against each other under two different sampling schemes, and observe that a larger correlation between the uncertainties tends to result in more computationally challenging optimization models. We also observe the same set of inequalities to provide the tightest upper and lower bounds in our computational experiments.

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TYPE Journal Article YEAR 2018
DOIOSTI

MueLu User's Guide

Berger-Vergiat, Luc; Glusa, Christian; Hu, Jonathan J.; Siefert, Christopher; Tuminaro, Raymond S.; Mayr, Matthias; Prokopenko, Andrey; Wiesner, Tobias

This is the official user guide for MUELU multigrid library in Trilinos version 12.13 (Dev). This guide provides an overview of MUELU, its capabilities, and instructions for new users who want to start using MUELU with a minimum of effort. Detailed information is given on how to drive MUELU through its XML interface. Links to more advanced use cases are given. This guide gives information on how to achieve good parallel performance, as well as how to introduce new algorithms Finally, readers will find a comprehensive listing of available MUELU options. Any options not documented in this manual should be considered strictly experimental.

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TYPE SAND Report YEAR 2018
DOIOSTI

Evaluation of High Temperature Plastics as a Ceramic Replacement

Redline, Erica; Dial, Brent E.; Stavig, Mark E.; Sawyer, Patricia S.; Miller, Lance L.

This report describes the 2015-2017 fiscal year research efforts to evaluate high temperature plastics as replacement materials for ceramics in electrical contact assemblies. The main objective of this work was to assess the feasibility of replacing existing high-price ceramic inserts with a polymeric material. Current ceramic parts are expensive due to machining costs and can suffer brittle failure. Therefore, replacing the ceramic with a more cost-effective material — in this case a plastic — is highly desirable. Not only are plastics easier to process, but they can also eliminate final tooling and are less brittle than ceramics. This effort used a three-phase approach: selection of appropriate materials determined by a comprehensive literature review, performance of an initial thermal stability screening, understanding of aging behavior under normal and off-normal conditions, and evaluation of performance at elevated temperatures. Two polymers were determined to meet the desired criteria: polybenzimidazole, and Vespel® SP-1 polyimide. Polymer derived ceramics may also be useful but will require further development of molding capabilities that were beyond the scope of this program.

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TYPE SAND Report YEAR 2018
DOIOSTI
Results 26001–26100 of 99,299
Results 26001–26100 of 99,299