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排序方式: 共有650条查询结果,搜索用时 31 毫秒
61.
Slawomir J. Ambroziak Ryszard J. Katulski Jaroslaw Sadowski Jacek Stefanski 《通讯和计算机》2013,(9):1247-1252
The aim of this paper is the path loss modelling for the radiolocation services in radio communication networks, particularly in cellular networks. The main results of the measurements obtained in the physical layer of the UMTS are introduced. A new method for the utilization of the multipath propagation phenomenon to improve the estimation of the distance between the MS (mobile station) and the BS (base station) is outlined. This method significantly increases the quality of location services in systems which use a radio interface with DS (direct sequence) CDMA (code division multiple access). 相似文献
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63.
The asymptotic stabilisation problem of a class of large-scale interconnected systems is considered, where the non-linear interconnections between subsystems satisfy quadratic constraints that are functions of the whole system's state vector. A decentralised combined observer-controller compensator is proposed and analysed, where the subsystems’ state vectors are estimated using local sliding mode observers. The closed-loop system driven by the proposed decentralised compensator is guaranteed to be asymptotically stable subject to two conditions that are easily verifiable. Simulation results illustrate the effectiveness of the proposed decentralised combined observer-controller compensator. 相似文献
64.
This paper describes key aspects of remote service invocation in federations of OSGi containers. It refers to the OSGi Remote Service Admin specification and describes its efficient implementation over message‐oriented middleware. Scalability problems of several different approaches to implementation are identified, and a solution in a form of innovative Remote Service Admin model extension is proposed. The extension, named On‐demand Remote Service Admin, is analyzed and validated in the context of a motivating scenario. Validation includes performance and scalability evaluation, which confirms that all assumed requirements have been satisfied by the constructed prototype. Finally, the presented research is compared with related works. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
65.
ElŻbieta Hajnicz 《Journal of Logic, Language and Information》1999,8(1):17-43
In this paper we show that properties of non-linear time structures have not been studied enough. Axioms forcing the existence of a branching point in a branching area of a structure are presented for various classes of structures. We show also that the classical Dedekind continuity axiom does not work well in non-linear structures and we suggest stronger versions. Finally, some interdependencies between the axioms presented are proved. 相似文献
66.
When V. V. Nalimov in his important book Naukometriya (Moskva 1969) postulated research on the process of developement of science with the aid of quantitative methods, he listed
many different indicators. There were among them the number and growth of scientific publications — books and periodicals,
the number of scientists, the level of expenditure.
This article shows that the importance of these indicators was recognised by earlier authors.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
67.
Ryszard Rywotycki 《Food chemistry》2007,101(2):540-548
The studies aimed to determine the occurrence and formation of nitrosamine contamination levels with dimethylnitrosamine (DMNA) and diethylnitrosamine (DENA) in meat of various kinds, species and genders of farm animals slaughtered at meat processing plants all over Poland. The meat after cooling, cutting and jointing was classified, then comminuted and divided into several experimental variants. Moreover, the effect of the most frequent functional additives used in food industry, such as sodium chloride and sodium ascorbate, and baking process upon the level of the meat pollution was researched. Nitrosamine (DMNA and DENA) concentrations were assessed by Varian 3400 gas chromatograph coupled with Finnigan MAT ITD 800 spectrometer. The quantitative and qualitative states of respective nitrosamines were determined by comparing the chromatogram values. 相似文献
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69.
Testing of electrical properties of nanocomposites (Co0,45Fe0,45Zr0,1)x + (Al2O3)1+x within the concentration range of 0.30 < x < 0.65, produced by means of magnetron sputtering of a target composed of stripes of metallic alloy and dielectric, has been carried out. It has been found that the studied materials contain metallic nanoparticles of a diameter ranging from 6 to 10 nm. Alternating current conduction at x < 0.50 is realized by hopping mechanism while at x > 0.50 metallic conductivity is observed.The obtained results have been analyzed using a model of hopping conductivity in the egime developed earlier. This analysis allowed to extract dependences of activation energy ΔEτ and times τ in a hopping regime after isochronous (15 min) thermal annealings within the range from 293 K to 673 K. 相似文献
70.