Browsing by Author "Shu, Jiang"
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- Computational Steering in the Problem Solving Environment WBCSimShu, Jiang; Watson, Layne T.; Ramakrishnan, Naren; Kamke, Frederick A.; Deshpande, Shubhangi (Department of Computer Science, Virginia Polytechnic Institute & State University, 2009)Computational steering allows scientists to interactively control a numerical experiment and adjust parameters of the computation on-the-fly and explore “what if ” analysis. Computational steering effectively reduces computational time, makes research more efficient, and opens up new product design opportunities. There are several problem solving environments (PSEs) featuring computational steering. However, there is hardly any work explaining how to enable computational steering for PSEs embedded with legacy simulation codes. This paper describes a practical approach to implement computational steering for such PSEs by using WBCSim as an example. WBCSim is a Web based simulation system designed to increase the productivity of wood scientists conducting research on wood-based composites manufacturing processes. WBCSim serves as a prototypical example for the design, construction, and evaluation of small-scale PSEs. Various changes have been made to support computational steering across the three layers—client, server, developer—comprising the WBCSim system. A detailed description of the WBCSim system architecture is presented, along with a typical scenario of computational steering usage.
- Data Driven Surrogate Based Optimization in the Problem Solving Environment WBCSimDeshpande, Shubhangi; Watson, Layne T.; Shu, Jiang; Kamke, Frederick A.; Ramakrishnan, Naren (Department of Computer Science, Virginia Polytechnic Institute & State University, 2009)Large scale, multidisciplinary, engineering designs are always difficult due to the complexity and dimensionality of these problems. Direct coupling between the analysis codes and the optimization routines can be prohibitively time consuming due to the complexity of the underlying simulation codes. One way of tackling this problem is by constructing computationally cheap(er) approximations of the expensive simulations, that mimic the behavior of the simulation model as closely as possible. This paper presents a data driven, surrogate based optimization algorithm that uses a trust region based sequential approximate optimization (SAO) framework and a statistical sampling approach based on design of experiment (DOE) arrays. The algorithm is implemented using techniques from two packages—SURFPACK and SHEPPACK that provide a collection of approximation algorithms to build the surrogates and three different DOE techniques—full factorial (FF), Latin hypercube sampling (LHS), and central composite design (CCD)—are used to train the surrogates. The results are compared with the optimization results obtained by directly coupling an optimizer with the simulation code. The biggest concern in using the SAO framework based on statistical sampling is the generation of the required database. As the number of design variables grows, the computational cost of generating the required database grows rapidly. A data driven approach is proposed to tackle this situation, where the trick is to run the expensive simulation if and only if a nearby data point does not exist in the cumulatively growing database. Over time the database matures and is enriched as more and more optimizations are performed. Results show that the proposed methodology dramatically reduces the total number of calls to the expensive simulation runs during the optimization process.
- An Experiment Management Component for the WBCSim Problem Solving EnvironmentShu, Jiang (Virginia Tech, 2002-12-13)This thesis describes a computing environment WBCSim and its experiment management component. WBCSim is a web-based simulation system used to increase the productivity of wood scientists conducting research on wood-based composite and material manufacturing processes. This experiment management component integrates a web-based graphical front end, server scripts, and a database management system to allow scientists to easily save, retrieve, and perform customized operations on experimental data. A detailed description of the system architecture and the experiment management component is presented, along with a typical scenario of usage.
- Experiment Management for the Problem Solving Environment WBCSimShu, Jiang (Virginia Tech, 2009-08-10)A problem solving environment (PSE) is a computational system that provides a complete and convenient set of high level tools for solving problems from a specific domain. This thesis takes an in-depth look at the experiment management aspect of PSEs, which can be divided into three levels: 1) data management, 2) change management, and 3) execution management. At the data management level, anything related to an experiment (computer simulation) should be stored and documented. A database management system can be used to store the simulation runs for a PSE. Then various high level interfaces can be provided to allow users to save, retrieve, search, and compare these simulation runs. At the change management level, a scientist should only focus on how to solve a problem in the experiment domain. Aside from running experiments, a scientist may only consider how to define a new model, how to modify an existing model, and how to interpret an experiment result. By using XML to describe a simulation model and unify various implementation layers, changing an existing model in a PSE can be intuitive and fast. At the execution management level, how an experiment is executed is the main concern. By providing a computational steering capability, a scientist can pause, examine, and compare the intermediate results from a simulation. Contrasted with the traditional way of running a lengthy simulation to see the result at the end, computational steering can leverage the user's expert knowledge on the fly (during the simulation run) and provide new insights and new product design opportunities. This thesis illustrates these concepts and implementation by using WBCSim as an example. WBCSim is a PSE that increases the productivity of wood scientists conducting research on wood-based composite materials and manufacturing processes. It integrates Fortran 90 simulation codes with a Web based graphical front end, an optimization tool, and various visualization tools. The WBCSim project was begun in 1997 with support from United States Department of Agriculture, Department of Energy, and Virginia Tech. It has since been used by students in several wood science classes, by graduate students and faculty, and by researchers at several forest products companies. WBCSim also serves as a test bed for the design, construction, and evaluation of useful, production quality PSEs.
- A problem solving environment for the wood-based composites industryKamke, Frederick A.; Watson, Layne T.; Lee, Jong-Nam; Shu, Jiang (Department of Computer Science, Virginia Polytechnic Institute & State University, 2005)Product quality and cost efficiency continue to grow in importance for the wood-based composites industry. The complex dynamics of the manufacturing process lends itself to the adoption of simulation models. Simulation models may be used to understand and manipulate the many parameters involved in the manufacturing process. However, most of the simulation models that have been developed over the last two decades have not been implemented due to a lack of continued technical support and a poor user interface. WBCSim is a prototype, Web based, problem solving environment (PSE) that was developed to assist manufacturers and scientists in the design and manufacture of selected wood-based composite products. At the heart of WBCSim is a collection of legacy codes, which are described here. This PSE demonstrates the possibility of implementing scientific computing into a manufacturing application.
- Unification of Problem Solving Environment Implementation Layers with XMLShu, Jiang; Watson, Layne T.; Ramakrishnan, Naren; Kamke, Frederick A.; North, Christopher L. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2005)This paper describes how XML is used to unify the implementation layers of a problem solving environment WBCSim. WBCSim is a Web based simulation system designed to increase the productivity of wood scientists conducting research on wood-based composites manufacturing processes. WBCSim serves as a prototypical example for the design, construction, and evaluation of small-scale problem solving environments. WBCSim supports five process models. A XML datasheet is tailored for each model. The WBCSim interface layer, server scripts and database management system all use this XML datasheet to improve the usability and maintainability of the three layers--client, server, developer--comprising the WBCSim system. A detailed description of the WBCSim system architecture is presented along with a typical scenario of usage.
- WBCSim: An Environment for Modeling Wood-Based Composites ManufacturingShu, Jiang; Watson, Layne T.; Zombori, B.G.; Kamke, Frederick A. (Department of Computer Science, Virginia Polytechnic Institute & State University, 2002)This paper describes a computing environment WBCSim that increases the productivity of wood scientists conducting research on wood-based composite materials and manufacturing processes. WBCSim integrates Fortran 90 simulation codes with a Web-based graphical front end, an optimization tool, and various visualization tools. WBCSim serves as an example for the design, construction, and evaluation of small-scale problem solving environments. WBCSim supports six models. A detailed description of the system architecture and a typical scenario of usage are presented, along with optimization and visualization features.