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The computerization of structural design has been accompanied by a reduction in reliability, as the engineering has been transferred from the human to a 'black box.' With the current introduction of expert systems, a more powerful...
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The computerization of structural design has been accompanied by a reduction in reliability, as the engineering has been transferred from the human to a 'black box.' With the current introduction of expert systems, a more powerful generation of software, a study was undertaken to determine the effect of the new technology on reliability and safety. The study found that expert systems are inherently more reliable than conventional algorithmic programs, due to the accessibility of the knowledge bases and the explanation capability. Improved testing procedures are also possible. An examination of each of the phases of structural design has shown that the use of expert systems will be beneficial. The most urgent need for expert systems technology was found in the analysis phase as intelligent pre- and post-processors for finite element and other structural analysis software.
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This publication proposes a discussion of the general problem of validatingnumerical models for nonlinear, transient dynamics. The predictive quality of a numerical model is generally assessed by comparing the computed response to...
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This publication proposes a discussion of the general problem of validatingnumerical models for nonlinear, transient dynamics. The predictive quality of a numerical model is generally assessed by comparing the computed response to test data. If the correlation is not satisfactory, an inverse problem must be formulated and solved to identify the sources of discrepancy between test and analysis data. Some of the most recent work summarized in this publication has focused on developing test-analysis correlation and inverse problem solving capabilities for nonlinear vibrations. Among the difficulties encountered, we cite the necessity to satisfy continuity of the response when several finite element optimization are successively carried out and the need to propagate variability throughout the optimization of the model's parameters. After a brief discussion of the formulation of inverse problems for nonlinear dynamics, the general principles which, we believe, should guide future developments of inverse problem solving are discussed. In particular, it is proposed to replace the resolution of an inverse problem with multiple forward, stochastic problems. The issue of defining an adequate metrics for test-analysis correlation is also addressed. Our approach is illustrated using data from a nonlinear vibration testbed and an impact experiment both conducted at Los Alamos National Laboratory in support of the advanced strategic computing initiative and our code validation and verification program.
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This study is an attempt to better understand the role of structural and211 ecological factors on infant health for Black and White women in New York City 211 (excluding Staten Island). This study examines the impact of residentia...
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This study is an attempt to better understand the role of structural and211 ecological factors on infant health for Black and White women in New York City 211 (excluding Staten Island). This study examines the impact of residential 211 segregation on neighborhood economic indicators, neighborhood quality, access to 211 health care, and individual perinatal risk factors and subsequent birthweight 211 among 138, 761 Black and White women who gave birth in 1991 or 1992. Using a 211 conceptual framework combining two theoretical perspectives on the role of 211 discrimination and segregation in birth outcomes, a multi-level dataset was 211 constructed that included individual, neighborhood and borough level variables. 211 The databases used for this study were the vital statistics birth records for 211 NYC, 1990 U.S. Census data, and United Hospital Fund NYC Community Health Atlas 211 database.
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We investigate in the proton form factor the possibility to have a zero in the space-like region. As a consequence the e-p differential cross-section would have a dip and a second maximum which are accessible to experiment. If the...
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We investigate in the proton form factor the possibility to have a zero in the space-like region. As a consequence the e-p differential cross-section would have a dip and a second maximum which are accessible to experiment. If the existence of such structure would be revealed it would be very important for understanding the composite nature of the proton. (Atomindex citation 11:554103)
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We report a real-time, two-dimensional light scattering study of the evolution of structure in a two component nonionic micelle system during phase separation via spinodal decomposition. Our principal finding is that domain growth...
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We report a real-time, two-dimensional light scattering study of the evolution of structure in a two component nonionic micelle system during phase separation via spinodal decomposition. Our principal finding is that domain growth proceeds much slower than the cube root of time prediction for simple binary fluids. In fact, the growth kinetics can be empirically described as a stretched exponential approach to a pinned domain size. Although the kinetics are not yet understood, this anomalous behavior may be due to the ability of the spherical micelles to reorganize into more complex structures. The domain structure also shows some anomalies. Although at short times the expected structure factor for a critical quench is observed, at long times the structure factor crosses over to the off-critical form. However, in all cases the average scattered intensity is proportional to the cube of the domain size. These findings are discussed in comparison to standard theories of and experimental work on binary fluids.
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We report a real-time, two-dimensional light scattering study of the evolution of structure in a two component nonionic micelle system during phase separation via spinodal decomposition. Our principal finding is that domain growth...
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We report a real-time, two-dimensional light scattering study of the evolution of structure in a two component nonionic micelle system during phase separation via spinodal decomposition. Our principal finding is that domain growth proceeds much slower than the cube root of time prediction for simple binary fluids. In fact, the growth kinetics can be empirically described as a stretched exponential approach to a pinned domain size. Although the kinetics are not yet understood, this anomalous behavior may be due to the ability of the spherical micelles to reorganize into more complex structures. The domain structure also shows some anomalies. Although at short times the expected structure factor for a critical quench is observed, at long times the structure factor crosses over to the off-critical form. However, in all cases the average scattered intensity is proportional to the cube of the domain size. These findings are discussed in comparison to standard theories of and experimental work on binary fluids.
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We review the program of parity violation in the scattering of polarized electrons at JLab. Results are presented from recent experiments measuring the weak form factors, which in turn measure the contribution of strange quarks to...
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We review the program of parity violation in the scattering of polarized electrons at JLab. Results are presented from recent experiments measuring the weak form factors, which in turn measure the contribution of strange quarks to the elastic form factors. In addition, we discuss the physics of parity violation in deep inelastic scattering, which will become possible with the upgrade of the JLab energy to 12 GeV.
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Hadronic form factors are objects that contribute significantly to our understanding of the structure of matter. The simplest hadronic system is the pion, whose electromagnetic structure is given by a single form factor (F). In th...
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Hadronic form factors are objects that contribute significantly to our understanding of the structure of matter. The simplest hadronic system is the pion, whose electromagnetic structure is given by a single form factor (F). In this talk the results from the most recent Fpi at Jefferson Lab are presented.
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Changes in the political, social, economic, and technological environments of organizations have provided an increasingly turbulent context within which organizations must operate. One consequence of these changes is growing conce...
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Changes in the political, social, economic, and technological environments of organizations have provided an increasingly turbulent context within which organizations must operate. One consequence of these changes is growing concern with developing structural forms which adapt more easily. The Air Force has also become interested in this issue and has requested study focusing on some non-traditional options to more traditional functional structure. This paper reports results of a pilot work for this effort. Included are a discussion of the importance of structure, theoretical models for structural variations and alternatives, a methodology which can be used to study structural issues, and an application of both methodology and theory to specific Air Force situations (aircraft maintenance and systems acquisition). Discussion is provided by answers to specific questions regarding structural issues in the Air Force.
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Factors pertaining to the problem of quantifying the value of human life are enumerated, and some of the schemes and rationale that have been used in such quantification are reviewed. Factors considered in the loss of life involve...
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Factors pertaining to the problem of quantifying the value of human life are enumerated, and some of the schemes and rationale that have been used in such quantification are reviewed. Factors considered in the loss of life involve direct economic costs such as hospitalization and legal services as well as indirect economic costs such as loss of future production and consumption. Also considered are non-economic losses such as the suffering of a bereaved family. Distinctions are drawn between economically motivated questions and those based on social and moral values. Other issues concern the difference between a statistical life and a specific individual, and scale effect (loss of X number of lives per X number of events). A survey of studies made in the U.S. and France on the value of human life is presented. Specific schemes used to assign a dollar value to a human life include assessments for traffic accidents, air crashes, and castastrophic events. In evaluating money costs due to illness or death, several calculations are given. It is noted that additional factors need to be considered in basing a valuation of human life on expected lifetime earnings. Results of various studies' estimates of the value of human life are presented in tabular form.
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