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1.
Real-time multimedia applications have to use forward error correction (FEC) anderror concealment techniques to cope with
losses in today’s best-effort Internet. The efficiency of these solutions is known however to depend on the correlation between
losses in the media stream. In this paper we investigate how the packet size distribution affects the packet loss process,
that is, the distribution of the number of lost packets in a block, the related FEC performance and the average loss run length.
We present mathematical models for the loss process of the MMPP+M/D/1/K and the MMPP+M/M/1/K queues; we validate the models
via simulations, and compare the results to simulation results with an MPEG-4 coded video trace. We conclude that the deterministic
packet size distribution (PSD) not only results in lower stationary loss probability than the exponential one, but also gives
a less correlated loss process, both at a particular average link load and at a particular stationary loss probability as
seen by the media stream.Our results show that for applications that can only measure the packet loss probability, the effects
of the PSD on FEC performance are higher in access networks, where a single multimedia stream might affect the multiplexing
behavior. Our results show that the effects of the PSD on FEC performance are higher in access networks, where a single multimedia
stream might affect the multiplexing behavior and thus can improve the queuing performance by decreasing the variance of its
PSD. 相似文献
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Sorption of protactinium from HNO3 solutions with the aid of phosphate resins and various oxides is studied in connection with concentration of Pa
231. Manganese oxide w as found to be the most efficient sorbent, with a high degree of freedom from iron, aluminum, and calcium impurities upon precipitation. The most pronounced differentiation between manganese and protactinium was achieved in solvent extraction by chlorex. The behaviorofprotactinium in response to various techniques for separation of titanium and zirconium was studied, and it was shown that in the salicylate method protactinium undergoes complete coprecipitation with zirconium salicylate. These operations led to the recovery by concentration of Pa
231, the principal bulk component being zirconium.Translated from Atomnaya Énergiya, Vol. 16, No. 2, pp. 134–137, February, 1964 相似文献
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Vikt I. Spitsyn 《Atomic Energy》1964,16(4):472-474
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Ladányi Zsuzsanna Barta Károly Blanka Viktória Pálffy Benjámin 《Water Resources Management》2021,35(3):869-880
Water Resources Management - In the future, according to regional climate-model simulations, the Carpathian Basin (in Central Europe) is predicted to be exposed to intensifying weather extremes... 相似文献
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Guzanová Anna Draganovská Dagmar Ižaríková Gabriela Brezinová Janette Rajt’úková Viktória Živčák Jozef Hudák Radovan Janoško Erik Moro Róbert 《Journal of Mechanical Science and Technology》2021,35(10):4389-4404
Journal of Mechanical Science and Technology - The article deals with selective laser melting process using CoCrW powder. Our aim was to identify the influence of product position on the building... 相似文献
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Wiesel O Tóth IE Boldogkoi Z Hornyák A Bokor V Halász B Gerendai I 《Microscopy research and technique》2004,63(4):244-252
Using the transneuronal viral tracing method, the central nervous system (CNS) connections of the uterine horn were studied in virgin, pregnant, and in lactating rats. The frequency of viral labeling in the brain and the distribution of virus-infected neurons from the uterine horn were compared among groups. There was a marked difference in the frequency of viral labeling in the brain stem. In virgin rats more than half of the brain stems (5 out of 9) were labeled. In contrast, in pregnant animals viral-labeled neurons were detected in only a few cases (3 out of 16) and almost each brain stem of the lactating group was labeled (12 out of 13). A similar, less marked difference was observed in the hypothalamus. The pattern of distribution of infected neurons was similar in each group. In the brain stem, the nucleus of the solitary tract, dorsal motor nucleus of the vagus, area postrema, gigantocellular and paragigantocellular nucleus, ventrolateral medulla, A5 cell group, and caudal raphe nuclei were the most frequently labeled structures. In the diencephalon, viral-infected neurons were detected primarily in the hypothalamic paraventricular nucleus. The telencephalon was devoid of infected cells. Data suggest that the CNS control of the uterine horn varies depending on reproductive status. The low frequency of brain labeling in pregnant rats may be related to the almost complete lack of sympathetic fibers in the uterus prior to parturition and the very high frequency of labeling in lactating animals to the postpartum hyperinnervation of the uterus. 相似文献
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Co‐immobilized Whole Cells with ω‐Transaminase and Ketoreductase Activities for Continuous‐Flow Cascade Reactions 下载免费PDF全文
László Nagy‐Győr Emese Abaházi Dr. Viktória Bódai Dr. Péter Sátorhelyi Dr. Balázs Erdélyi Dr. Diána Balogh‐Weiser Prof. Dr. Csaba Paizs Dr. Gábor Hornyánszky Prof. Dr. László Poppe 《Chembiochem : a European journal of chemical biology》2018,19(17):1845-1848
An improved sol–gel process involving the use of hollow silica microspheres as a supporting additive was applied for the co‐immobilization of whole cells of Escherichia coli with Chromobacterium violaceum ω‐transaminase activity and Lodderomyces elongisporus with ketoreductase activity. The co‐immobilized cells with two different biocatalytic activities could perform a cascade of reactions to convert racemic 4‐phenylbutan‐2‐amine or heptan‐2‐amine into a nearly equimolar mixture of the corresponding enantiomerically pure R amine and S alcohol even in continuous‐flow mode. The novel co‐immobilized whole‐cell system proved to be an easy‐to‐store and durable biocatalyst. 相似文献
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Front Cover: Co‐immobilized Whole Cells with ω‐Transaminase and Ketoreductase Activities for Continuous‐Flow Cascade Reactions (ChemBioChem 17/2018) 下载免费PDF全文