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1.
High-speed air breathing propulsion systems have many attractive military and civil applications. The high propulsive efficiency of these systems allows the exploitation of speed, distance, and bigger payloads, or any combination of the three. The severe operating conditions of these systems require particular attention to overall thermal management of the engine/air-frame. Fuel-cooling the engine structure is a viable way of maintaining thermal balance over a range of flight conditions. Air Force applications have focused on using endothermic hydrocarbon fuels to address this issue because of their compatibility with the military operations. Recent ground tests of scramjet engines have demonstrated adequate performance utilizing state-of-the-art technology in materials. This progress has paved the way for an expendable flight test vehicle in the near future. In order to take full advantage of the capabilities of this propulsion system, advances in fuel-cooled structures, high temperature un-cooled materials, and increased heat capacity of hydrocarbon fuels will be needed to enable expendable systems to reach higher Mach numbers. An additional benefit would be realized in future reusable systems. 相似文献
2.
R Albrecht TC Awes C Baktash P Beckmann F Berger R Bock G Claesson G Clewing L Dragon A Eklund RL Ferguson A Franz S Garpman R Glasow HA Gustafsson HH Gutbrod J Idh P Jacobs K Kampert BW Kolb P Kristiansson IY Lee H Loehner I Lund FE Obenshain A Oskarsson I Otterlund T Peitzmann S Persson F Plasil AM Poskanzer M Purschke H Ritter S Saini R Santo HR Schmidt T Siemiarczuk SP Sorensen E Stenlund ML Tincknell GR Young 《Canadian Metallurgical Quarterly》1991,44(6):2736-2752
3.
The broadband wireless access industry, which provides high-rate network connections to stationary sites, has matured to the point at which it now has a standard for second-generation wireless metropolitan area networks. The IEEE standard 802.16, with its WirelessMANTM air interface, sets the stage for widespread and effective deployments worldwide. This article overviews the technical medium access control and physical layer features of this new standard 相似文献
4.
A foundational development of propositional fuzzy logic programs is presented. Fuzzy logic programs are structured knowledge bases including uncertainties in rules and facts. The precise specifications of uncertainties have a great influence on the performance of the knowledge base. It is shown how fuzzy logic programs can be transformed to neural networks, where adaptations of uncertainties in the knowledge base increase the reliability of the program and are carried out automatically. 相似文献
5.
Ralph Schreiber Britta ReinkeCarsten Vogt Joachim WertherGerd Brunner 《Powder Technology》2003,138(1):31-38
Various particles with sizes between 100 and 200 μm were encapsulated with waxes commonly used in technical coating applications. For this, a homogeneous mixture of molten paraffin and supercritical carbon dioxide was prepared in an autoclave and injected into the high-pressure fluidized bed through a nozzle from the bottom. Due to the different conditions in the mixing autoclave and the fluidized bed, the paraffin precipitated in the vicinity of the nozzle and adhered to the solid particles. A complete, thin, uniform, and solvent-free coating was produced. The use of two paraffins with different alkane compositions resulted in dissimilar spreads on glass beads due to their different glass transition temperatures. A smaller pressure drop across the nozzle led to more uniform and even coatings. Glass beads, ceramic spheres, potassium chloride, and lactose showed similar coating results, whereas different morphologies were observed with a plastic material, characterized by a rougher surface and a lower surface energy. The high quality of the coating was confirmed by standard dissolution tests with coated potassium chloride crystals and lactose agglomerates. 相似文献
6.
Eklund JA 《Applied ergonomics》1995,26(1):15-20
Several studies indicate a relationship between ergonomic work conditions and the quality of the work. The purpose of this study was to evaluate relationships between a number of ergonomic conditions and product quality in car assembly. The most physically demanding tasks, the tasks with the most difficult parts to assemble, and the most psychologically demanding tasks, were identified by interviews with experienced assembly workers. Information on quality deficiencies was obtained from the internal quality statistics of the company and from interviews with quality control personnel. The results showed that the quality deficiencies were three times as common for the work tasks with ergonomics problems, compared with the other tasks. An increased risk of quality deficiencies was seen for all three categories of ergonomics problems investigated. Direct causes of quality deficiencies were identified, such as discomfort from strained parts of the body, organizational factors and time pressure. The analyses pointed to certain types of task that were more likely than others to cause quality problems. The results also showed that an important factor for job satisfaction was the possibility for the workers to perform their tasks with high quality. The study therefore confirms close relationships between ergonomics and quality, and thereby points to the possibility of conducting integrated change programmes aimed at improving work quality and work conditions simultaneously. 相似文献
7.
8.
This paper investigates Swedish recycling centres from the users' perspective. The aim was to describe the characteristics and experiences of the users and their activities when sorting and disposing of waste, and to identify improvements for the users. The typical recycling centre user is a recently retired man, living in a house with a garden, having travelled 5 km alone in his own car. The users requested longer opening hours and better information available at home and at the recycling centre. The major difficulty for the users is to understand which fraction their waste belongs to, and consequently into which container they should throw it. The most important sources of sorting information, in addition to experience from earlier visits, are signs and asking the personnel. Although the service at recycling centres is perceived positively by a majority of users, substantial improvements can still be made, and a number of such suggestions are given. 相似文献
9.
Health care providers and governments are under pressure to maintain and improve the quality of care to an increasing volume
of critical care patients at either end of the life cycle, namely premature and ill term babies together with the elderly.
The provision of a service of critical care utilizing real time service-oriented architectures has the potential to enable
clinicians to be supported in the care of a greater number patients that are, perhaps more importantly, located elsewhere
to their intensive care units. This paper presents a review of recent research in the application of computing and IT to support
the service of critical care and determines the trends and challenges for the application of real time service-oriented architectures
within the domain. It then presents some case study–based research on the design of a service-oriented architecture-based
approach to support two aspects of critical care namely elderly care and neonatal intensive care to provide further context
to trends and opportunities. 相似文献
10.