Analysis pervades all aspects of naval engineering. It is used to determine requirements for new or upgraded systems and to explore concepts for their employment. It is used to evaluate performance. It is used to esta...
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Analysis pervades all aspects of naval engineering. It is used to determine requirements for new or upgraded systems and to explore concepts for their employment. It is used to evaluate performance. It is used to establish design characteristics. And it comes in many varieties. This paper addresses use and misuse of analysis in naval engineering. The paper is oriented toward managers of analytic endeavors rather than the practitioners of analysis. It does not deal in depth with how to perform particular analytic techniques. Instead it discusses general principles that should guide both the selection and application of analytic techniques. The paper identifies problems which are frequently encountered in analyses related to naval engineering and suggests ways to ameliorate their deleterious effects. These problems are addressed from both the perspective of the manager of analysis and that of the user or consumer of results from the analysis. Some of the challenges that face naval engineering analyses as a consequence of hardware and software improvements and of more sophisticated systems are also discussed.
作者：
FRANK, EHGRODZINSKY, AJContinuum Electromechanics Group
Laboratory for Electromagnetic and Electronic Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA U.S.A.
We have formulated a continuum model for linear electrokinetic transduction in cartilage. Expressions are derived for the streaming potential and streaming current induced by oscillatory, uniaxial confined compression...
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We have formulated a continuum model for linear electrokinetic transduction in cartilage. Expressions are derived for the streaming potential and streaming current induced by oscillatory, uniaxial confined compression of the tissue, as well as the mechanical stress generated by a current density or potential difference applied to the tissue. The experimentally observed streaming potential and current-generated stress response, measured on the same specimens, are compared with the predictions of the theory over a wide frequency range. The theory compares well with the data for reasonable values of cartilage intrinsic mechanical parameters and electrokinetic coupling coefficients. Experiments also show a linear relationship between the stimulus amplitude and the transduction response amplitude, within the range of stimulus amplitudes of interest. This observation is shown to be consistent with the predictions of the linear theory.
作者：
FRANK, EHGRODZINSKY, AJContinuum Electromechanics Group
Laboratory for Electromagnetic and Electronic Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA U.S.A.
Articular cartilage contains a high fixed charge density under physiological conditons associated primarily with the ionized proteoglycan molecules of the extracellular matrix. Oscillatory compression of cartilage usi...
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Articular cartilage contains a high fixed charge density under physiological conditons associated primarily with the ionized proteoglycan molecules of the extracellular matrix. Oscillatory compression of cartilage using physiological loads produces electrical potentials that have been shown previously to be the result of an electrokinetic (streaming) transduction mechanism. We have now observed two additional electromechanical phenomena not previously seen in cartilage or other soft tissues: ''streaming current'' and ''current-generated stress''. Sinusoidal mechanical compression induced a sinusoidal streaming current density through cartilage disks when the Ag/AgCl electrodes that were used to compress the cartilage were shorted together externally. Conversely, a sinusoidal current density applied to the tissue generated a sinusoidal mechanical stress within the tissue. Both these phenomena were found to be consistent with the same electrokinetic transduction mechanism responsible for the streaming potential. Changes in the measured streaming potential response that resulted from modification of both ionic strength and pH have provided additional insights into the molecular origins of these transduction processes. Finally, we have now observed streaming potentials in living cartilage maintained in organ culture, as well as in previously frozen tissue.
作者：
Pasquale, JosephComputer Systems Research Group
Computer Science Division Department of Electrical Engineering and Computer Sciences University of California BerkeleyCA94720 United States
A major fundamental problem in decentralized resource control in distributed systems is that in general, no decision-making node knows with complete certainty the current global state of the system. We present an arch...
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Performance analysis is the process of determining the predicted performance of a weapons system. It is generally used to examine predicted performance of systems in a variety of configurations and operational situati...
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Performance analysis is the process of determining the predicted performance of a weapons system. It is generally used to examine predicted performance of systems in a variety of configurations and operational situations; it is accomplished through a variety of techniques, from the computation of straightforward algebraic functions to complex computer simulations. Performance analysis is necessary throughout the life-cycle of weapons systems. It is used to help determine original requirements, for conceptual and detailed design, and to support operational planning and determine upgrade requirements. The development, maintenance, and consistent application of a set of system specific performance analysis methods have enhanced the development of many weapons systems. This paper is in the form of a tutorial on the application of performance analysis techniques, using the development of the Aegis weapons system as a source of examples, and stressing the value of performance analysis methods which have been designed specifically for the Aegis system.
作者：
GERSH, JRThe authoris a principal staff engineer at The Johns Hopkins University Applied Physics Laboratory
where he supervises the AAW Operations Section of the Combat Direction Group. Since joining JHU/APL in 1980 he has been involved in the specification development and testing of advanced surface combat direction systems specializing in the application of rule-based control mechanisms to command and control problems. In 1985-86 he chaired the Doctrine Working Group of the Naval Sea Systems Command's Combat Direction System Engineering Committee. Mr. Gersh served in the U.S. Navy from 1968 to 1977 as a sonar technician and as a junior officer (engineering and gunnery) aboard Atlantic Fleet frigates and as a member of the U.S. Naval Academy's Electrical Engineering faculty. He was educated at Harvard University and the Massachusetts Institute of Technology receiving S. B. S. M. and E. E. degrees in electrical engineering from the latter. He holds certificates as a commercial pilot and flight instructor and is a member of the U.S. Naval Institute the IEEE Computer Society and the American Association for Artificial Intelligence.
For the last four years the most advanced surface combat direction system (CDS) of the U.S. Navy has employed a limited knowledge-based control mechanism. Implemented in the Aegis Weapon System's command and decis...
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For the last four years the most advanced surface combat direction system (CDS) of the U.S. Navy has employed a limited knowledge-based control mechanism. Implemented in the Aegis Weapon System's command and decision element, this capability is called control by doctrine, and is a foundation for the Ticonderoga class cruisers' exceptional performance. Control by doctrine allows CIC personnel to direct that certain CDS functions be performed automatically upon tracks with specified characteristics. In effect, these CDS functions, from identification to engagement, can now be controlled through the specification and activation of general system response rules rather than by individual operator actions. The set of active rules, called doctrine statements, forms a system knowledge-base. The Advanced Combat Direction System, Block 1, successor to today's Naval Tactical Data System, will also employ control by doctrine. As part of a larger effort investigating Aegis/ACDS commonality issues, a Doctrine Working group was chartered to consider, among other things, implications for force-wide interoperability of multiple systems with such rule-based control mechanisms. The working group produced a set of design objectives for doctrine statement standardization across CDSs. Principal features of these objectives are described. The prospect of several such ships operating together in a battle group has raised questions as to the methods by which the actions of ships with those doctrinally-automated systems can best be coordinated. Related questions deal with specific design features for the support of such coordinated action. Work is now being carried out to investigate these questions. Combat system automation through doctrine statements is only one kind of rule-based control. Much work in the area of artificial intelligence deals with the use and maintenance of complex systems of rules, usually in non-real-time problem solving applications. Such systems are just now beginning
Synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) are enhanced resolution imaging radar systems. These systems receive coherent radar signal returns from an illuminated scene and use the signa...
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