摘要 :
The viewgraph presentation examines optimal design for precision, large aperture structures. Discussion focuses on aspects of design optimization, code architecture and current capabilities, and planned activities and collaborativ...
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The viewgraph presentation examines optimal design for precision, large aperture structures. Discussion focuses on aspects of design optimization, code architecture and current capabilities, and planned activities and collaborative area suggestions. The discussion of design optimization examines design sensitivity analysis; practical considerations; and new analytical environments including finite element-based capability for high-fidelity multidisciplinary analysis, design sensitivity, and optimization. The discussion of code architecture and current capabilities includes basic thermal and structural elements, nonlinear heat transfer solutions and process, and optical modes generation.
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An experimental and theoretical study of the CONDUIT sensitivity tools was conducted. The literature on sensitivity in nonlinear programming was reviewed to see in what ways it could be applied to CONDUIT. One result of this was t...
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An experimental and theoretical study of the CONDUIT sensitivity tools was conducted. The literature on sensitivity in nonlinear programming was reviewed to see in what ways it could be applied to CONDUIT. One result of this was the conclusion that the current insensitivity measure in CONDUIT is the right one. The question of scaling of the specifications in CONDUIT was also studied. Many simple examples were created, analyzed and, in most cases, solved. However, no general solution to the scaling problem was found. Instead, the appropriate scaling needs to be determined by review of a reasonable number of real aircraft design problems.
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A multilevel optimization approach which is applicable to nonhierarchic coupledsystems is presented. The approach includes a general treatment of design (or behavior) constraints and coupling constraints at the discipline level th...
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A multilevel optimization approach which is applicable to nonhierarchic coupledsystems is presented. The approach includes a general treatment of design (or behavior) constraints and coupling constraints at the discipline level through the use of norms. Three different types of norms are examined: the max norm, the Kreisselmeier-Steinhauser (KS) norm, and the 1(sub p) norm. The max norm is recommended. The approach is demonstrated on a class of hub frame structures which simulate multidisciplinary systems. The max norm is shown to produce system-level constraint functions which are non-smooth. A cutting-plane algorithm is presented which adequately deals with the resulting corners in the constraint functions. The algorithm is tested on hub frames with increasing number of members (which simulate disciplines), and the results are summarized.
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摘要 :
A multilevel optimization approach which is applicable to nonhierarchic coupled systems is presented. The approach includes a general treatment of design (or behavior) constraints and coupling constraints at the discipline level t...
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A multilevel optimization approach which is applicable to nonhierarchic coupled systems is presented. The approach includes a general treatment of design (or behavior) constraints and coupling constraints at the discipline level through the use of norms. Three different types of norms are examined: the max norm, the Kreisselmeier-Steinhauser (KS) norm, and the 1(sub p) norm. The max norm is recommended. The approach is demonstrated on a class of hub frame structures which simulate multidisciplinary systems. The max norm is shown to produce system-level constraint functions which are non-smooth. A cutting-plane algorithm is presented which adequately deals with the resulting corners in the constraint functions. The algorithm is tested on hub frames with increasing number of members (which simulate disciplines), and the results are summarized.
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Collaborative optimization is a new design architecture specifically created for large-scale distributed-analysis applications. In this approach, a problem is decomposed into a user-defined number of subspace optimization problems...
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Collaborative optimization is a new design architecture specifically created for large-scale distributed-analysis applications. In this approach, a problem is decomposed into a user-defined number of subspace optimization problems that are driven towards interdisciplinary compatibility and the appropriate solution by a system-level coordination process. This decentralized design strategy allows domain-specific issues to be accommodated by disciplinary analysts, while requiring interdisciplinary decisions to be reached by consensus. The present investigation focuses on application of the collaborative optimization architecture to the multidisciplinary design of a single-stage-to-orbit launch vehicle. Vehicle design, trajectory, and cost issues are directly modeled.
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The development of a coal gasification system design and mass and energy balance simulation program for the TVA and other similar facilities is described. The materials-process-product model (MPPM) and the advanced system for proc...
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The development of a coal gasification system design and mass and energy balance simulation program for the TVA and other similar facilities is described. The materials-process-product model (MPPM) and the advanced system for process engineering (ASPEN) computer program were selected from available steady state and dynamic models. The MPPM was selected to serve as the basis for development of system level design model structure because it provided the capability for process block material and energy balance and high-level systems sizing and costing. The ASPEN simulation serves as the basis for assessing detailed component models for the system design modeling program. The ASPEN components were analyzed to identify particular process blocks and data packages (physical properties) which could be extracted and used in the system design modeling program. While ASPEN physical properties calculation routines are capable of generating physical properties required for process simulation, not all required physical property data are available, and must be user-entered.
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Following the collapse of the Route 198 bridge over the Baltimore-WashingtonParkway in 1989, the FHWA determined that there was a need to reassess, on a national level, the specifications currently used to design, construct, and i...
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Following the collapse of the Route 198 bridge over the Baltimore-WashingtonParkway in 1989, the FHWA determined that there was a need to reassess, on a national level, the specifications currently used to design, construct, and inspect falsework and formwork for highway bridge structures. Towards that end, the FHWA commissioned this synthesis to identify existing information on this subject and present in one document. This effort has included a survey of United States and Canadian highway departments, and comprehensive literature search for related publications. The objective of the study has been to identify the current state-of-the-practice in the United States and abroad, based on a review of available standards, specifications, literature, and published research. Published literature from the United States, Canada, Great Britain, Australia, New Zealand, Japan, and several European countries was identified and forms the basis of this report. This information is summarized and discussed under the general headings of falsework, formwork, and scaffolding. This discussion is followed by an examination of review and inspection procedures. The development of a unified standard, or code of practice, is recommended.
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Helsinki University of Technology, Laboratory of Bridge Engineering has commenceda research program Development of wood bridges in 1992. The first part of the project is Surveying of the background information, which is published ...
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Helsinki University of Technology, Laboratory of Bridge Engineering has commenceda research program Development of wood bridges in 1992. The first part of the project is Surveying of the background information, which is published in Finnish. The report is an excerpt of the above mentioned report. It includes only the conclusions of the report and the literature survey section. In the first section of the report there is a historical study of wood bridges. In the second section of the report the need for the development of wood bridges in Finland is reviewed and the benefits of wood in comparison with other materials are examined. In the third section of the report alternative wood materials available are reviewed. The fourth section is the main part of the report. There are listed books and papers published in periodicals on either wood bridges or other wood structures. Also the existence of that material in the various Helsinki University of Technology Libraries is clarified.
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A part of the joint Caltrans and University of California at Berkeley researchproject focused on the outrigger knee joint systems found in bents of elevated freeway bridges. Experiments on two half-scale as-built models confirmed ...
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A part of the joint Caltrans and University of California at Berkeley researchproject focused on the outrigger knee joint systems found in bents of elevated freeway bridges. Experiments on two half-scale as-built models confirmed the poor performance of existing outrigger knee joint systems observed after the 1989 Loma Prieta earthquake. Two seismic upgrading strategies, a 'ductile' and a 'strong' strategy, were proposed and tested on prototype specimens. The 'strong' strategy was chosen for the final seismic upgrade design. Two variations of the final design, one made using a post-tensioned reinforced concrete jacket, the other made using a steel jacket, were tested on three specimens. The seismic design guidelines, recommending the steel jacket upgrade, contain three parts: an upgrade design procedure based on capacity design principles; and energy balanced hysteresis model for dynamic analysis and tools for predicting or verifying the performance of the upgraded outrigger knee joints, developed in parallel with the experiments; and recommendations for detailing the steel jacket upgrade and a design example.
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