Douglas S. McCorkle

Optimization of heat transfer utilizing graph based evolutionary algorithms

Abstract This paper examines the use of graph based evolutionary algorithms (GBEAs) for optimization of heat transfer in a complex system. The specific case examined in this paper is the optimization of heat transfer in a biomass cookstove utilizing three-dimensional computational fluid dynamics to generate the fitness function. In this stove hot combustion gases are used to heat a cooking surface. The goal is to provide an even spatial temperature distribution on the cooking surface by redirecting the flow of combustion gases with baffles. The variables in the optimization are the position and size of the baffles, which are described by integer values. GBEAs are a novel type of EA in which a topology or geography is imposed on an evolving population of solutions. The choice of graph controls the rate at which solutions can spread within the population, impacting the diversity of solutions and convergence rate of the EAs. In this study, the choice of graph in the GBEAs changes the number of mating events required for convergence by a factor of approximately 2.25 and the diversity of the population by a factor of 2. These results confirm that by tuning the graph and parameters in GBEAs, computational time can be significantly reduced.

Using the Semantic Web technologies in virtual engineering tools to create extensible interfaces

Ideas and tools developed for the Semantic Web can also be applied to and integrated with engineering tools and software. The ideas upon which the Semantic Web are founded, along with the technologies that are used to implement it, provide a platform on which virtual engineering tools and interfaces can be extended to create a web in which contextual information is readily accessible to engineers. When the Semantic Web and virtual engineering methods are fully realized, computer hardware and networking capabilities will work to provide information and tools to access information meaningfully. The question that must be answered today is: how will information be integrated in a manner that will allow commercial and proprietary software tools to remain separate while also being integrated so that the end user can control and query these tools with little to no knowledge of the tools’ implementation or inner-working details? The answer to this question will depend largely on the ability to implement open interfaces and schemas that can evolve over time as well as open source toolkits that enable development teams to collaborate at a high level. This paper discusses potential applications of the Semantic Web to explore these questions. In addition, specific capabilities being developed in VE-Suite are discussed.

Improving Design Diversity Using Graph Based Evolutionary Algorithms

Graph based evolutionary algorithms (GBEAs) have been shown to have superior performance to evolutionary algorithms on a variety of evolutionary computation test problems as well as on some engineering applications. One of the motivations for creating GBEAs was to produce a diversity of solutions with little additional computational cost. This paper tests that feature of GBEAs on three problems: a real-valued multi-modal function of varying dimension, the plus-one-recall-store (PORS) problem, and an applied engineering design problem. For all of the graphs studied the number of different solutions increased as the connectivity of the graph underlying the algorithm decreased. This indicates that the choice of graph can be used to control the diversity of solutions produced. The availability of multiple solutions is an asset in a product realization system, making it possible for an engineer to explore design alternatives.

Applications of Virtual Engineering in Combustion Equipment Development and Engineering

The implementation of a virtual engineering system at John Zink Company, LLC is starting to change the engineering and development processes for industrial combustion equipment. This system is based on the virtual engineering software called VE-Suite being developed at the Virtual Reality Applications Center (VRAC) of Iowa State University. The goal of the John Zink virtual engineering system is to provide a virtual platform where product design, system engineering, computer simulation, and pilot plant test converge in a virtual space to allow engineers to make sound engineering decisions. Using the virtual engineering system, design engineers are able to inspect the layout of individual components and the system integration through an immersive stereo 3D visualization interface. This visualization tool allows the engineer not only to review the integration of subsystems, but also to review the entire plant layout and to identify areas where the design can be improved. One added benefit is to significantly speed up the design review process and improve the turn around time and efficiency of the review process. Computational Fluid Dynamics (CFD) is used extensively at John Zink to evaluate, improve, and optimize various combustion equipment designs and new product development. Historically, design and product development engineers relied on CFD experts to interpret simulation results. With the implementation of the virtual engineering system, engineers at John Zink are able to assess the performance of their designs using the CFD simulation results from a first person perspective. The virtual engineering environment provided in VE-Suite greatly enhances the value of CFD simulation and allows engineers to gain much needed process insights in order to make sound engineering decisions in the product design, engineering, and development processes. Engineers at John Zink are now focusing on taking the virtual engineering system to the next level: to allow for real-time changes in product design coupled with high-speed computer simulation along with test data to optimize product designs and engineering. It is envisioned that, when fully implemented, the virtual engineering system will be integrated into the overall engineering process at John Zink to deliver products of the highest quality to its customers and significantly shorten the development cycle time for a new generation of highly efficient and environmentally friendly combustion products.Copyright

VE-Suite: A Software Framework for Design-Analysis Integration During Product Realization

Product realization is a complex decision-making process requiring intensive interactions between engineers, especially between designers and analysts. It is necessary to develop effective tools to help them manage the heterogeneous software tools, multidisciplinary engineering models, and information flows during the process. Multidisciplinary analysis results must be synthesized with the design models to support designers making decisions based on an overall understanding about the product’s performance. Meanwhile, along the product realization timeline, these tools, models, and information must be constantly updated and modified. In this paper, we present a flexible software framework, VE-Suite, to handle the “two-dimensional” characteristics of design-analysis integration. The data structure and communication mechanism in VE-Suite enable convenient design-analysis integration not only across the boundary of disciplines, but also along the product realization timeline. An ongoing design scenario of a hydraulic mixing nozzle is presented; some temporary results are introduced to demonstrate the significance of the two-dimensional integration and the effectiveness of the VE-Suite.© 2005 ASME

A Case Study of the Implementation and Maintenance of a Fee for Service Lighting System for a Rural Village in Sub Saharan Africa

Electricity is a critical need for the rural poor in developing countries. Often this need is met with disposable batteries. This results in high cost and problems with disposal. For example it was recently reported that an isolated rural village in West Africa with a population of 770 uses more than 21,000 disposable batteries per year and that purchase of these batteries accounts for 20–40% of household expense. As a result many organizations are seeking way to meet the need for village energy. This paper presents a case study of one such experience. In this study the efforts to meet the lighting needs of a cluster of eight rural villages with a population of approximately 8,000 people are discussed. A key aspect of this discussion is the challenge of creating a continuing and sustainable village lighting solution. In this case the technology chosen to implement a lighting system was a distributed micro-grid managed locally in each village. The success of this lighting grid has been in large part due to the continuing support of the local micro-grid system both financially and through continued engagement to maintain and upgrade the micro-grid systems.Copyright

Proper Orthogonal Decomposition-Based Reduced Order Model of a Hydraulic Mixing Nozzle

In this work, a reduced order model is constructed for a hydraulic mixing nozzle using proper orthogonal decomposition. Data from several CFD computations are collected to provide the data for input to the reduced order model and flow is projected onto the most dominant principal axes to study the flow structures. Flow structures are compared for the original and optimized shape nozzles to study the effect of changing the nozzle’s shape on the flow characteristics. This study also addresses issues regarding the time required for collecting CFD data and how it has been reduced by using a modified convergence criterion.

Interactive Design Using CFD and Virtual Engineering

Virtual engineering is a powerful concept, defined as a technology that integrates geometric models and related engineering tools such as analysis and simulation, optimization and decision-making tools, etc. within a computer generated environment that facilitates multidisciplinary and collaborative product realization [1]. Virtual engineering applications can be constructed from scratch with high-level programming languages. However, since the end-user of the virtual engineering application is most likely not a programming expert, high-level support is needed to provide the user with the capability to construct his own application in an intuitive manner and with minimal coding. In this paper, we present a framework of the virtual engineering environment and its implementation, identify the general requirements for a virtual engineering application, and summarize the architecture. A virtual engineering application on computational fluid dynamics (CFD)-based interactive design is used to motivate the research as well as to evaluate the performance of the system. The sample application is related to the coal transport system of a coal-fired power plant. Finally, the topics for future research are given.

An application of graph based evolutionary algorithms for diversity preservation

A difficult application case of evolutionary algorithms is that in which individual fitness evaluations take several processor-minutes to a few processor-hours. The design of evolutionary algorithms with such expensive fitness evaluation differs substantially from the norm where fitness evaluation is rapid. In this paper we apply evolutionary algorithms to a thermal systems engineering design problem - the design of a biomas cook stove currently in use in Central America. Fitness evaluation involves the use of computational fluid dynamics (CFD) modeling of the flow of hot air and heat transport within the stove to equalize the surface temperature. The goal is to optimize the placement and size of baffles that deflect hot gasses underneath the cook top of the stove. Three techniques are used to permit evolutionary algorithm to function on this challenging problem using a population of relatively small size. First, computations are performed on a Linux cluster machine yielding a large, fixed performance increase. Second, the resolution of the mesh for CFD computations used a minimal; mesh that yields acceptable fidelity of CFD computations. Third, a diversity preserving technique called a graph based evolutionary algorithm (GBEA) is used to retain population diversity during evolution. A usable stove design, subsequently deployed in the field, was located by the evolutionary algorithm. In this paper we demonstrate that GBEAs preserve diversity on this baffle design problem and give evidence that highly connected graphs is a good choice for future work on analogous CFD problems. Diversity preservation is a function of both tournament size and the connectivity (geography) of the graph used.

An Overview of Computational Environments for Engineering

The concept of a computational environment as an engineering tool was first discussed in the 1960’s. As envisioned today integrated computational environments bring together the engineering models, tools, and visualizations that describe an engineered product or process into a single interactive environment that can be used throughout the life of the product. Many of the components of computational environments have been integrated into systems such as problem solving environments, model integration frameworks, and virtual environments. However the development of an integrated (or complete) computational environment that supports engineering from initial concept, through analysis and design, manufacturing, operation, and retirement or decommissioning has been illusive. This paper reviews the goals of integrated computational environments and proposes a set of tools that are needed to develop and support development of these integrated computational environments and should be pursued by the AIAA Meshing, Visualization, and Computational Environments Technical Committee.