26 research outputs found

    Computational Tools and Facilities for the Next-Generation Analysis and Design Environment

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    This document contains presentations from the joint UVA/NASA Workshop on Computational Tools and Facilities for the Next-Generation Analysis and Design Environment held at the Virginia Consortium of Engineering and Science Universities in Hampton, Virginia on September 17-18, 1996. The presentations focused on the computational tools and facilities for analysis and design of engineering systems, including, real-time simulations, immersive systems, collaborative engineering environment, Web-based tools and interactive media for technical training. Workshop attendees represented NASA, commercial software developers, the aerospace industry, government labs, and academia. The workshop objectives were to assess the level of maturity of a number of computational tools and facilities and their potential for application to the next-generation integrated design environment

    Structures Division 1994 Annual Report

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    The NASA Lewis Research Center Structures Division is an international leader and pioneer in developing new structural analysis, life prediction, and failure analysis related to rotating machinery and more specifically to hot section components in air-breathing aircraft engines and spacecraft propulsion systems. The research consists of both deterministic and probabilistic methodology. Studies include, but are not limited to, high-cycle and low-cycle fatigue as well as material creep. Studies of structural failure are at both the micro- and macrolevels. Nondestructive evaluation methods related to structural reliability are developed, applied, and evaluated. Materials from which structural components are made, studied, and tested are monolithics and metal-matrix, polymer-matrix, and ceramic-matrix composites. Aeroelastic models are developed and used to determine the cyclic loading and life of fan and turbine blades. Life models are developed and tested for bearings, seals, and other mechanical components, such as magnetic suspensions. Results of these studies are published in NASA technical papers and reference publication as well as in technical society journal articles. The results of the work of the Structures Division and the bibliography of its publications for calendar year 1994 are presented

    Aeronautical engineering: A continuing bibliography with indexes (supplement 240)

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    This bibliography lists 629 reports, articles, and other documents introduced into the NASA scientific and technical information system in May, 1989. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

    Knowledge composition methodology for effective analysis problem formulation in simulation-based design

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    In simulation-based design, a key challenge is to formulate and solve analysis problems efficiently to evaluate a large variety of design alternatives. The solution of analysis problems has benefited from advancements in commercial off-the-shelf math solvers and computational capabilities. However, the formulation of analysis problems is often a costly and laborious process. Traditional simulation templates used for representing analysis problems are typically brittle with respect to variations in artifact topology and the idealization decisions taken by analysts. These templates often require manual updates and "re-wiring" of the analysis knowledge embodied in them. This makes the use of traditional simulation templates ineffective for multi-disciplinary design and optimization problems. Based on these issues, this dissertation defines a special class of problems known as variable topology multi-body (VTMB) problems that characterizes the types of variations seen in design-analysis interoperability. This research thus primarily answers the following question: How can we improve the effectiveness of the analysis problem formulation process for VTMB problems? The knowledge composition methodology (KCM) presented in this dissertation answers this question by addressing the following research gaps: (1) the lack of formalization of the knowledge used by analysts in formulating simulation templates, and (2) the inability to leverage this knowledge to define model composition methods for formulating simulation templates. KCM overcomes these gaps by providing: (1) formal representation of analysis knowledge as modular, reusable, analyst-intelligible building blocks, (2) graph transformation-based methods to automatically compose simulation templates from these building blocks based on analyst idealization decisions, and (3) meta-models for representing advanced simulation templates VTMB design models, analysis models, and the idealization relationships between them. Applications of the KCM to thermo-mechanical analysis of multi-stratum printed wiring boards and multi-component chip packages demonstrate its effectiveness handling VTMB and idealization variations with significantly enhanced formulation efficiency (from several hours in existing methods to few minutes). In addition to enhancing the effectiveness of analysis problem formulation, KCM is envisioned to provide a foundational approach to model formulation for generalized variable topology problems.Ph.D.Committee Co-Chair: Dr. Christiaan J. J. Paredis; Committee Co-Chair: Dr. Russell S. Peak; Committee Member: Dr. Charles Eastman; Committee Member: Dr. David McDowell; Committee Member: Dr. David Rosen; Committee Member: Dr. Steven J. Fenve

    Infusion of Robustness into the Product Platform Constructal Theory Method

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    Today, mass customization has emerged as a manufacturing paradigm for a number of enterprises to efficiently and effectively satisfy customers requirements for product variety. The competitive nature of todays market makes it necessary for designers to have a methodology for designing customized products in such a dynamic environment. The Product Platform Constructal Theory Method (PPCTM), developed by Dr. Gabriel Hernandez, provides designers a methodical approach for synthesizing multiple modes of managing variety in the development of product platforms for customized products. The use of the PPCTM results in a hierarchical organization of the modes of managing customization, as well as the specification of their range of application across the product platform. The focus in this thesis is to augment the PPCTM in order to develop an effective product platform design method that alleviates three of its major limitations: inability to deal with uncertain distributions of demand, changing design parameters and changing extents of marketplaces. The infusion of concepts of robustness helps to address the first two limitations making the product platforms unaffected by large variations in demand and design parameters. The compromise Decision Support Problem is proposed to address the third limitation of changing extents of marketplaces by making tradeoffs between objectives of the initial market extent and future probable extensions. The result of this work is an augmented PPCTM that facilitates the synthesis of multiple modes for managing product variety in the presence of a dynamic environment. The augmented method is used to design a line of customizable pressure vessels and hand exercisers.M.S.Committee Chair: Mistree, Farrokh; Committee Member: Allen, Janet; Committee Member: Rosen, Davi

    Aeronautical engineering: A continuing bibliography with indexes (supplement 276)

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    This bibliography lists 705 reports, articles, and other documents introduced into the NASA scientific and technical information system in Feb. 1992. Subject coverage includes: design, construction, and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

    The Longer Term Effects of Federal Subsidies on Firm Commercialization and Survival:Evidence from the Advanced Technology Program

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    The goal of this dissertation is to determine the longer term (5-10 year) causal impact of federal R&D subsidies on firms’ survival outcomes and commercialization behavior. The data are small firms which applied to the 1998-2000 Advanced Technology Program (ATP) competitions. A variant of the research design pioneered by Heckman (1979) allows for inherent pre-award differences between awarded and non-awarded firms to be taken into account. This dissertation finds that receiving an ATP award has a positive and significant causal impact on a firm’s survival chances and new product announcements, but not on the more general likelihood of it commercializing any of its research.Doctor of Philosoph

    Aeronautical engineering: A continuing bibliography with indexes (supplement 223)

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    This bibliography lists 423 reports, articles, and other documents introduced into the NASA scientific and technical information system in January, 1988

    Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 248)

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    This publication is a cumulative index to the abstracts contained in Supplements 236 through 247 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included -- subject, personal author, corporate source, foreign technology, contract number, report number and accession number
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