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排序方式: 共有59条查询结果,搜索用时 171 毫秒
1.
Mohammed Hawa Jamal S. Rahhal Dia I. Abu-Al-Nadi 《Peer-to-Peer Networking and Applications》2012,5(3):279-291
Peer-to-Peer (P2P) traffic has increased rapidly over the past few years, with file sharing providing the main drive behind
such traffic. In this work we perform a measurement study of the content shared over the popular BitTorrent P2P file sharing
network. We mathematically model the file size distributions of shared files after categorizing them into Audio, Video, Archive
and CD image classes. For each of these categories we look into the most popular shared file formats and investigate their
file size statistics. This provides an important milestone to building a realistic simulation framework for P2P systems, and
for future analytical modeling of P2P networks. 相似文献
2.
3.
对双齿轮——六杆机构进行了系统地研究.建立了输出运动方程,简要介绍了该机构所能实现的六种运动特性,把两个间歇条件联立解方程,解决了间歇机构的综合问题,推荐了选取机构参数的方法和范围,讨论了机构参数对运动和动力特性的影响,总结了该机构的主要优点和适用范围. 相似文献
4.
5.
The unicellular eukaryote Tetrahymena is a popular model for the study of lipid metabolism. Less attention, however, has been given to the inositol phospholipids
of the cell, although it is known that this class of lipids plays an important role in eukaryotic cell signaling. Tetrahymena pyriformis phosphatidylinositol was isolated, purified, and characterized by proton nuclear magnetic resonance analysis and [2-3H]myoinositol labeling. Labeling was also used for polyphosphoinositide (phosphatidylinositol phosphate and phosphatidylinositol
bisphosphate) identification. Tetrahymena inositol phospholipids were found to belong to the diacylglycerol group, although major Tetrahymena phospholipids, phosphatidylcholine and aminoethylphosphonoglycerides, have been found to be mainly alkylacylglyceroderivatives.
Further characterization of Tetrahymena phosphatidylinositol by gas chromatographic analysis indicated that 80% of fatty acids were myristic acid and plamitic acid.
This is also in contrast to the fatty acid profile of Tetrahymena phosphatidylcholine and phosphatidylethanolamine, with respect both to the fatty acid length and degree of unsaturation,
and may indicate that specific diacylglycerol species are connected with the phosphatidylinositol metabolism in this cell.
Treatment of [3H]inositol-labeled Tetrahymena cells with mastoparan, a G-protein-activating peptide, induced changes in the polyphosphoinositide levels, suggesting that
inositol phospholipids may form in Tetrahymena a functional signaling system similar to that of higher eukaryotes. Addition of 10 μM mastoparan resulted in a rapid and
transient increase in [3H]phosphatidylinositol phosphate followed by a decrease in [3H]phosphatidylinositol bisphosphate. Similar changes in lipids have been reported when phosphoinositide-phospholipase C pathway
is activated in both animal and plant cells. 相似文献
6.
Streit D.C. Tan K.L. Dia R.M. Liu J.K. Han A.C. Velebir J.R. Wang S.K. Trinh T.Q. Chow P.-M.D. Lui P.H. Yen H.C. 《Electron Device Letters, IEEE》1991,12(4):149-150
The authors have fabricated 0.1-μm T-gate pseudomorphic (PM) InGaAs power high-electron-mobility transistors (HEMTs) with record power and gain performance at 94 GHz. Devices with 40-μm gate peripheries achieved 10.6-mW output power with 7.3-dB gain and 14.3% power-added efficiency (PAE). Devices with 160-μm gate peripheries achieved 62.7-mW output power with 4.0-dB gain and 13.2% PAE. The authors believe the superior performance of these devices is due to the combination of a short 0.1-μm T-gate, high-quality material, optimized device profile, and the reduction in source inductance due to source vias 相似文献
7.
Multiple input multiple output (MIMO) systems showed good utilization of channel characteristics. In MIMO systems multiple
signals are transmitted using multiple antenna system. This provides each receiver the combined signals and hence, array processing
techniques helps in reducing the effects of interference among them. In this paper we devise the use of pre-coded MIMO system
to reduce the effects of frequency selectivity and hence, enhance the systems capacity and/or reduce the bit error rate. In
this technique we introduce a temporal pre-coder on each antenna signal; this creates a deterministic multi-path signals similar
to signals received when the channel is multi-path fading channel. The same antenna signal will arrive at each receiver forming
orthogonal sub-space and the receiver will be simple add and delay of the received signals. Ant colony optimization is used
in this paper to select the best pre-code. Results showed that we can diagonalize the channel matrix and practically eliminate
the interference for frequency selective fading channel. Simulation of two transmitting two receiving antennas pre-coded MIMO
system showed that the capacity can be doubled. 相似文献
8.
Amina Meslem Aliou Dia Claudine Beghein Mouhammad El Hassan Ilinca Nastase Pierre-Jean Vialle 《Building and Environment》2011
The general context of the present study is the design of high induction HVAC air diffusers by means of passive jet control. When the diffuser is a perforated panel with lobed orifices (Meslem et al. 2010), the optimization of jet induction consists in improving the orifice’s geometry, the spacing between orifices and their arrangement on the panel. In this study, the flow field of a turbulent twin cross-shaped jet is investigated numerically using the standard k-ε model, the Shear Stress Transport (SST) k-ω model and the Reynolds Stress Model (RSM). The results are compared with PIV measurements. The objective is to assess their capability and limitations to predict the significant features of twin jet flow when the flow is numerically resolved through a lobed diffuser. It is shown that the k-ε and RSM models are more appropriate for predicting potential jet core length, the change in jet centreline streamwise velocity, and flow expansion in the symmetry plane of the twin jet flow. However, these models overestimate the overall flow expansion and the jet volumetric flow rate. The SST k-ω model seems more appropriate for the prediction of such dynamic integral quantities. A high level of turbulent kinetic energy predicted by the k-ε and RSM models in the near field of jets is probably the reason for this overestimation of jet induction. The SST k-ω model would appear to be the most appropriate tool for optimizing orifice design, orifice to orifice spacing and relative orifice orientation on a perforated panel diffuser. 相似文献
9.
10.
Abdalla?A.?ObeidatEmail author Maen?A.?Gharaibeh Dia?H.?Al?Samarh Mohammad?H.?Qaseer Nabil?Y.?Ayoub 《Journal of Superconductivity and Novel Magnetism》2011,24(6):1911-1916
The magnetization and the initial susceptibility have been calculated for a one-dimensional linear chain structured dilute
ferrofluid considering nearest neighbor magnetic interaction for N-particles. The initial susceptibility is calculated as a function of the orientation angle between the field and the chain
direction. Our results predict Curie–Weiss behavior for a one-dimensional magnetic fluid, and showed that the ordering temperature
T
0 depends on the particles separation in a very complicated way. This more general case of calculation reduces to simple results
found by the Dimer and Trimer models when N equals 2 and 3, respectively. 相似文献