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61.
The thermodynamic cycle of a resonant, MEMS-based, micro heat engine is characterized. The micro heat engine is an external combustion engine made of a cavity encapsulated between two membranes. The cavity is filled with saturated liquid–vapor mixture working fluid. Heat is added to and rejected from the engine at a frequency corresponding to the resonant frequency of the engine. Both pressure–volume and temperature-entropy diagrams are used to investigate the thermodynamic cycle of the resonant micro heat engine. The results show that the working cycle is nearly rectangular in shape and consists of two constant temperature processes and two constant volume processes. We hypothesize that major sources of irreversibility in the engine are heat transfer over finite temperature differences during heat addition and rejection, heat transfer into and out of engine thermal mass, viscous losses due to liquid working fluid motion, and heat escape from the engine to the surroundings. The maximum pressure and volume changes measured inside the engine cavity are 45?Pa and 0.55?mm3, respectively. The results show that for a heat addition of 1?mJ, the engine operates over a very small temperature difference. The small operating temperature difference is mostly attributable to the large thermal storage of the engine structure, the membranes and the wicks. The measured second law efficiency of the micro heat engine is 16?%. 相似文献
62.
AW Nichols 《Canadian Metallurgical Quarterly》1981,12(3):533-538
While the concept of a "right to health care" has been evolving in the United States, this should be distinguished from "the right to health," guaranteed in the constitutions of many socialist countries. In an effort to promote "quality of life" for their citizens, governments can, and do provide health care, but this does not always lead to health. In so doing, governments open access to care for those previously underserved--or unserved. For the United States at this time the goal becomes one of assuring equity, which will likely be achieved by locally based private and/or governmental entities, federated for greater efficiency and regulated by federal and state governments. Such programs will be staffed by a new breed of physician, the medical student of today. 相似文献
63.
A moving grid algorithm is presented for simulation of 3D oxidation processes. The algorithm combines local displacement of
mesh points according to material velocity and local mesh cleanup. Several examples are shown that demonstrate the capabolity
to simulate both the growth of thin layers of oxide during polysilicon gate reoxidation, as well at stress dependent growth
of 3D locos oxides. 相似文献
64.
MAGORZATA LEWANDOWSKA WIESAW WITNICKI RZEJ PITKOWSKI† & ZDZISAW JASIESKI† 《Journal of microscopy》2006,223(3):275-278
Single crystals of pure Cu and Cu‐8%Al with two initial orientations, {112}〈111〉 and {112}〈110〉, were subjected to monotonic compression in channel‐die at room temperature (293 K). The dislocation microstructure and local crystallography were investigated by transmission electron microscopy after different amounts of deformation. Various factors, such as initial single crystal orientation, chemical composition and amount of plastic deformation, were analysed in order to determine their influence on the microstructure evolution, local orientation variations and strain localization phenomena. 相似文献
65.
Kate Sanders Sally Fincher Dennis Bouvier Gary Lewandowski Briana Morrison Laurie Murphy Marian Petre Brad Richards Josh Tenenberg Lynda Thomas Richard Anderson Ruth Anderson Sue Fitzgerald Alicia Gutschow Susan Haller Raymond Lister Renée McCauley John McTaggart Christine Prasad Terry Scott Dermot Shinners-Kennedy Suzanne Westbrook Carol Zander 《Expert Systems》2005,22(3):121-128
Abstract: This paper presents a case study of the use of a repeated single‐criterion card sort with an unusually large, diverse participant group. The study, whose goal was to elicit novice programmers' knowledge of programming concepts, involved over 20 researchers from four continents and 276 participants drawn from 20 different institutions. In this paper we present the design of the study and the unexpected result that there were few discernible systematic differences in the population. The study was one of the activities of the National Science Foundation funded Bootstrapping Research in Computer Science Education project (2003). 相似文献
66.
A complete knowledge based procedure for the design and manufacture of a round hole broach tool is described. The knowledge based design system (KBDS) produces a tool specification from user inputs describing the task to be performed. These design results are then used by the knowledge base to generate a geometric CAD/CAM representation, which can be utilized directly to display a drawing of the tool or to generate a CNC program for producing it. The process of formulating a knowledge-based design system demonstrates: the integration of expertise from experts, handbooks and theory; the awareness of restrictions on the scope of design that can be handled by a given system: the use of failure handling mechanisms to detect design failures and either adjust the emerging design or indicate infeasibility. 相似文献
67.
Viscous water and gels have been proven to be more effective on forest fires than plain water. In 1963 and 1964, a new member
of this family of fire retardants was tested. The authors describe the properties and characteristics of the compound, report
the results of laboratory and field tests, and compare its effectiveness to that of plain water and other viscosity agents. 相似文献
68.
69.
STANISŁAW K. DUDA 《International journal of control》2013,86(5):1387-1399
This paper presents a new theory for determining dynamic output feedback of the least order for a linear, time-invariant, controllable and observable SIMO system, such that poles of the closed-loop system lie in a given region Γ in the complex plane. When some poles have prespecified stationary locations in the complex plane, dynamic output feedback is obtained in the sense that the remaining poles lie in Γ This theory applies to continuous-time as well as discrete-time systems. Here a design algorithm for complete system realization and an illustrative example are given. 相似文献
70.