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排序方式: 共有635条查询结果,搜索用时 14 毫秒
41.
42.
Sai S. Niwa E. Mase K. Nishibori M. Inoue J. Obuchi M. Harada T. Ito H. Mizutani K. Kizu M. 《Communications Magazine, IEEE》2009,47(11):120-127
Roadside-to-vehicle and vehicle-to-vehicle communication systems have been proposed as part of ITS development to help achieve vehicle safety and realize more secure road traffic environments. In this article we first introduce several typical applications and their radio range requirements for vehicle safety communication systems to clarify the technical point of view. Then we show some field experiment results in an urban area in Tokyo to investigate and verify the radio propagation characteristics and the quality of communications by using a wireless radio prototype system. Finally, we conclude that the current prototype system has potential to fulfill the radio range requirements of vehicle safety communications, but there are still lots of issues that need to be addressed. 相似文献
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45.
M Utsumi K Moriguchi H Takahashi C Kinoshita A Togari M Mizutani N Ohno 《Journal of electron microscopy》1999,48(2):139-145
The ultrastructure of the parathyroid gland (PTG) of the UM-X7.1 cardiomyopathic hamster (the UM-X7.1) was qualitatively and quantitatively compared with that of the normal hamster. In the UM-X7.1, the Golgi apparatus and rER were well developed compared with those of the control hamster. Morphometric analysis revealed that the mean values of the Golgi apparatus, rER and large vacuolar bodies were significantly greater in the UM-X7.1 than in the normal hamster and the mean value of lipid droplets was significantly less in the UM-X7.1 than in the normal hamster. Ultrastructurally, we consider that in the UM-X7.1, the synthesis and release of the parathyroid hormone may be activated by an excessive amount of circulating catecholamine, and the functional activity of the PTG may be higher than that in the normal hamster. 相似文献
46.
Identifying network density and scale economies for Japanese water supply organizations 总被引:3,自引:0,他引:3
Within this analysis we determine the optimal size (that is, with the minimum average cost) of a water supply enterprise
and reconsider the matter of scale economies, using sample data from Japanese water supply organizations. After surveying
evidence from previous studies of scale economies in the water supply industry, we estimate cost functions with three different
cost models: the log-linear, translog and translog with a hedonic function. We obtain the result that economies of network
density do exist, but that there are slight diseconomies of scale at the sample mean point. The optimal size of a water supply
organization would be one supplying a population of approximately 766,000 people.
Received: 10 March 2000 / Accepted: 8 January 2001 相似文献
47.
This paper is providing a design and evaluation methodology for biomass utilization networks (B-NETs) planning in local areas. The methodology is an effort to integrate various exertions of many researchers as well as stakeholders in the biomass field including process technologies, local area classification and renewable energy mechanisms to design and evaluate B-NETs. The proposed design methodology has three steps: classification, problem formulation and suggesting solution methods. The core part of planning the B-NETs utilization methodology is the superstructure that is a super class model for the processes of biomass utilization networks that has to be built for the local area. The biomass utilization superstructure (BUSS) relates the biomass resources to their products, available processes, and possible future processes of utilization in static manner. Although the local area BUSS is static in nature, it shows the decision makers what kinds of B-NETs are, or can be, available in their area. It is important to note that for each super class process there exists a number of elemental technologies, or what we call unit process (UP), that can perform the job under the same condition with different processing constraint. To support the design and operation process a technological information infrastructure (TII) needs to be built to work as an information pool and simulation tool. With the support of TII and the BUSS different scenarios can be synthesized, analyzed and compared. Scenarios development enables the designer to check processing alternatives as well as biomass promotion mechanisms that fit the concerns of various stakeholders. The results of the methodology application can be given in the form of suggestions of a specific network class(es) or scenarios that can be applied in a class of localities with the same characteristics. Following to methodology configuration, a proposal for optimization methods is discussed and a case study for comparing biomass network scenarios in mountainous city is introduced. 相似文献
48.
Takashi Ogihara Nobuyasu Mizutani Masanori Kato 《Journal of the American Ceramic Society》1989,72(3):421-426
Monodispersed ZrO2 seed particles which were prepared by hydrolysis of zirconium alkoxide solutions were allowed to grow by further addition of zirconium alkoxide and water under conditions in which new particles do not nucleate and grow. The particle growth mechanism is presumed to be a surface reaction in which the rate-determining step is a first-order polynuclearlayer growth mechanism. With this method of powder preparation, it is possible to precisely control the particle size, and it may be useful for applications in ceramic processing. 相似文献
49.
High-frequency measurements of 1.5-μm gatelength AlGaAs/InGaAs pseudomorphic HEMTs have been performed at temperatures ranging from 77 to 463 K. A 28% increase and 27% decrease in f T were observed by changing the temperature from 300 to 77 K and from 300 to 463 K, respectively. The effective saturation velocity evaluated from the total delay time, 1/2πf T, versus reciprocal I DS relation reveals almost the same temperature dependence as f T. It is also shown that the temperature dependence is similar to that of calculated velocity at high electric fields but not to that at low fields. This suggests that the temperature dependence of the HEMT performance is determined by that of the saturation velocity in the channel 相似文献
50.
Kazunori Shimamura Shigeki Masaki Hiroya Tanigawa 《International Journal of Satellite Communications and Networking》1991,9(5):355-362
The optimum BISDN teleconference service for business, called hypermedia teleconference, is designed based on research into typical business activities and ATM, the most promising BISDN architecture. Service characteristics are determined by analysing the daily work practices of a large set of businessmen. It is shown that communication tasks occupy 44 per cent of the working day. The analysis further shows that some 60 per cent of all communication tasks could be performed through an advanced digital teleconference service. Hypermedia teleconference is designed to satisfy the needs of business through personal communication terminals and ATM public networks. The terminals effectively allocate the BISDN's high-speed transmission capability between a number of subchannels that realize distributed multipoint connection links and multimedia paths. The terminals use a new variable-bit-rate ATM codec created to realize high quality video. Users can easily create full featured teleconferences without a centralized connection facility. Terminals allow the synergistic combination of video, voice, telewriting, telepointing and document transmission services. 相似文献