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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Satellite power systems (SPS) concept definition study. Volume 2, part 1: System engineering

Top level trade studies are presented, including comparison of solid state and klystron concepts, higher concentration on the solar cells, composite and aluminum structure, and several variations to the reference concept. Detailed trade studies are presented in each of the subsystem areas (solar array, power distribution, structures, thermal control, attitude control and stationkeeping, microwave transmission, and ground receiving station). A description of the selected point design is also presented.

Hanley, G. M.↗
NASA NTRS1980

Coal gasification systems engineering and analysis. Appendix D: Cost and economic studies

The detailed cost estimate documentation for the designs prepared in this study are presented. The include: (1) Koppers-Totzek, (2) Texaco (3) Babcock and Wilcox, (4) BGC-Lurgi, and (5) Lurgi. The alternate product cost estimates include: (1) Koppers-Totzek and Texaco single product facilities (methane, methanol, gasoline, hydrogen), (2) Kopers-Totzek SNG and MBG, (3) Kopers-Totzek and Texaco SNG and MBG, and (4) Lurgi-methane and Lurgi-methane and methanol.

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NASA NTRS1980

Coal gasification systems engineering and analysis. Appendix H: Work breakdown structure

A work breakdown structure (WBS) is presented which encompasses the multiple facets (hardware, software, services, and other tasks) of the coal gasification program. The WBS is shown to provide the basis for the following: management and control; cost estimating; budgeting and reporting; scheduling activities; organizational structuring; specification tree generation; weight allocation and control; procurement and contracting activities; and serves as a tool for program evaluation.

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NASA NTRS1982

Thermal system engineering experiment

The technical feasibility of a solar thermal collector to provide process steam in an industrial environment was determined. The form of the experiment was an industrial field test.

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NASA NTRS1983

Development of a Multilevel Optimization Approach to the Design of Modern Engineering Systems

A general algorithm is proposed which carries out the design process iteratively, starting at the top of the hierarchy and proceeding downward. Each subproblem is optimized separately for fixed controls from higher level subproblems. An optimum sensitivity analysis is then performed which determines the sensitivity of the subproblem design to changes in higher level subproblem controls. The resulting sensitivity derivatives are used to construct constraints which force the controlling subproblems into chosing their own designs so as to improve the lower levels subproblem designs while satisfying their own constraints. The applicability of the proposed algorithm is demonstrated by devising a four-level hierarchy to perform the simultaneous aerodynamic and structural design of a high-performance sailplane wing for maximum cross-country speed. Finally, the concepts discussed are applied to the two-level minimum weight structural design of the sailplane wing. The numerical experiments show that discontinuities in the sensitivity derivatives may delay convergence, but that the algorithm is robust enough to overcome these discontinuities and produce low-weight feasible designs, regardless of whether the optimization is started from the feasible space or the infeasible one.

Barthelemy, J. F. M.↗
NASA NTRS1986

An improved multilevel optimization approach for the design of complex engineering systems

Multilevel optimization methods are being considered for the design of complex systems on distributed networks of computers or even parallel processors. An obstacle to the use of multilevel methods is that they can be computationally expensive because of the cycling necessary to account for the coupling between the subproblems. This research effort aims at increasing the efficiency of multilevel optimization by adapting two techniques that are widely used in conventional one-level optimization: constraint approximation and temporary constraint deletion. These improvements are implemented and tested on three-, ten- and 52-bar planar truss designs. The results show that for larger problems (approximately 100 design variables and larger), the cost of analysis dominates the total cost so that multilevel optimization is no more expensive than one-level optimization. If parallel processing is used or the analysis process itself is decomposed, then multilevel optimization stands to become more economical than one-level optimization.

Barthelemy, J.-F. M.↗
NASA NTRS1984

Optimization in the systems engineering process

The objective is to look at optimization as it applies to the design process at a large aircraft company. The design process at Lockheed-Georgia is described. Some examples of the impact that optimization has had on that process are given, and then some areas that must be considered if optimization is to be successful and supportive in the total design process are indicated. Optimization must continue to be sold and this selling is best done by consistent good performance. For this good performance to occur, the future approaches must be clearly thought out so that the optimization methods solve the problems that actually occur during design. The visibility of the design process must be maintained as further developments are proposed. Careful attention must be given to the management of data in the optimization process, both for technical reasons and for administrative purposes. Finally, to satisfy program needs, provisions must be included to supply data to support program decisions, and to communicate with design processes outside of the optimization process. If designers fail to adequately consider all of these needs, the future acceptance of optimization will be impeded.

Lemmerman, L. A.↗
NASA NTRS1988

Human operator response to error-likely situations in complex engineering systems

The causes of human error in complex systems are examined. First, a conceptual framework is provided in which two broad categories of error are discussed: errors of action, or slips, and errors of intention, or mistakes. Conditions in which slips and mistakes might be expected to occur are identified, based on existing theories of human error. Regarding the role of workload, it is hypothesized that workload may act as a catalyst for error. Two experiments are presented in which humans' response to error-likely situations were examined. Subjects controlled PLANT under a variety of conditions and periodically provided subjective ratings of mental effort. A complex pattern of results was obtained, which was not consistent with predictions. Generally, the results of this research indicate that: (1) humans respond to conditions in which errors might be expected by attempting to reduce the possibility of error, and (2) adaptation to conditions is a potent influence on human behavior in discretionary situations. Subjects' explanations for changes in effort ratings are also explored.

Morris, Nancy M.↗
NASA NTRS1989

Systems engineering and integration of control centers in support of multiple programs

The NASA Johnson Space Center's new Multiprogram Control Center (MPCC) addresses the control requirements of complex STS payloads as well as unmanned vehicles. An account is given of the relationship of the MPCC to the STS Mission Control Center, with a view to significant difficulties that may be encountered and solutions thus far devised for generic problems. Examples of MPCC workstation applications encompass telemetry decommutation, engineering unit conversion, data-base management, trajectory processing, and flight design.

Miller, David N.↗
NASA NTRS1993

Systems engineering and integration and management for manned space flight programs

This paper discusses the history of SE&I management of the overall program architecture, organizational structure and the relationship of SE&I to other program organizational elements. A brief discussion of the method of executing the SE&I process, a summary of some of the major lessons learned, and identification of things that have proven successful are included.

Morris, Owen↗
NASA NTRS1993

Political and institutional factors affecting systems engineering

External groups have a significant impact on NASA's programs. Ten groups affecting NASA are identified, and examples are given for some of the them. Methods of dealing with these external inputs are discussed, the most important being good and open two way communications and an objective attitude on the part of the NASA participants. The importance of planning ahead, of developing rapport with these groups, and of effective use of NASA contractors is covered. The need for an overall strategic plan for the U.S. space program is stressed.

Yardley, John F.↗
NASA NTRS1993

Open environments to support systems engineering tool integration: A study using the Portable Common Tool Environment (PCTE)

A study of computer engineering tool integration using the Portable Common Tool Environment (PCTE) Public Interface Standard is presented. Over a 10-week time frame, three existing software products were encapsulated to work in the Emeraude environment, an implementation of the PCTE version 1.5 standard. The software products used were a computer-aided software engineering (CASE) design tool, a software reuse tool, and a computer architecture design and analysis tool. The tool set was then demonstrated to work in a coordinated design process in the Emeraude environment. The project and the features of PCTE used are described, experience with the use of Emeraude environment over the project time frame is summarized, and several related areas for future research are summarized.

Eckhardt, Dave E., Jr.↗
NASA NTRS1995

[Development of Engineering Systems for Space Station Freedom]

From January, 1990 through September, 1995, Cleveland State University (CSU) and Lewis Research Center (LeRC) participated in a research cooperative agreement. Extensive study and experimentation were done by CSU on research technologies, methods, and techniques employed by the Space Station Freedom (SSF) project and, later, the Space Experiments Division (SED). In spite of many problems occasioned by the virtual cancellation of Space Station Freedom at LeRC, and organizational and financial problem at LeRC, CSU was able to do valuable work in the study and improvement of research operating methods there.

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NASA NTRS1999

Aerospace Engineering Systems and the Advanced Design Technologies Testbed Experience

Continuous improvement of aerospace product development processes is a driving requirement across much of the aerospace community. As up to 90% of the cost of an aerospace product is committed during the first 10% of the development cycle, there is a strong emphasis on capturing, creating, and communicating better information (both requirements and performance) early in the product development process. The community has responded by pursuing the development of computer-based systems designed to enhance the decision-making capabilities of product development individuals and teams. Recently, the historical foci on sharing the geometrical representation and on configuration management are being augmented: 1) Physics-based analysis tools for filling the design space database; 2) Distributed computational resources to reduce response time and cost; 3) Web-based technologies to relieve machine-dependence; and 4) Artificial intelligence technologies to accelerate processes and reduce process variability. The Advanced Design Technologies Testbed (ADTT) activity at NASA Ames Research Center was initiated to study the strengths and weaknesses of the technologies supporting each of these trends, as well as the overall impact of the combination of these trends on a product development event. Lessons learned and recommendations for future activities are reported.

VanDalsem, William R.↗