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排序方式: 共有102条查询结果,搜索用时 15 毫秒
1.
We consider the transmission of K binary phase-shift keying signals over M diversity channels through a rich scattering environment. Improved group detection rules are proposed to mitigate the effect of the improper multiaccess interference, and an enhancement of the system receive diversity order is shown to be obtained. For example, it is demonstrated that a further gain of |g~|/2 per group is obtained compared with conventional group detection, where |g~| is the interfering group size. In addition, when there is only one antenna per group, the considered receiver with the improved detection rules is equivalent to the decorrelator. In this case, it is shown that (K-1) interferers can be ed out, and that an M-(K-1/2) receive diversity order is achieved, compared with only M-/sup 2/K+1 with the conventional detection rules. Numerical results will further put in evidence such gains.  相似文献   
2.
Five labdane diterpenoids, austroinulin, iso-austroinulin, sterebin E, sterebin E acetate, and sterebin A acetate, along with hydrocarbons, aliphatic alcohols, β-amyrin, β-sitosterol and stigmasterol were isolated from the chloroform soluble fraction of the methanol extract of Stevia rebaudiana leaves. Chlorogenic and caffeic acids were isolated from the EtOAc fraction. All the isolated compounds were identified using spectral tools. The chloroform and methanol extracts proved significant anti-inflammatory effect and caused marked inhibition of carrageenan-induced paw oedema in rats.  相似文献   
3.
The influence of processing conditions and interfacial modification on the morphology evolution and the composition range within which fully co‐continuous high density polyethylene/polystyrene blend structures can exist during blending in a single screw extruder was studied. Blends ranging from pure A to pure B component, with and without compatibilizer, were prepared under two different shear rates. It was found that high shear rates displaced the breakdown–coalescence balance of the dispersed nodules to the side of coalescence, narrowing the percolation domain and the critical composition for full co‐continuity decreased with increasing shear rates. The addition of a tri‐block compatibilizer induced the percolation threshold of the polystyrene phase to begin at lower percentages of polyethylene but the phase inversion point did not change. The experimental results are discussed in the light of various theoretical models. Copyright © 2005 Society of Chemical Industry  相似文献   
4.
Multimedia Tools and Applications - Studies of visual attention of patients with Dementia such as Parkinson’s Disease Dementia and Alzheimer Disease is a promising way for non-invasive...  相似文献   
5.
In this work, we investigate the effect of the thermal insulation by leather wastes (wet-blue chrome shavings and buffing dust) and carpentry wastes (wood shavings and sawdust) on the energy consumption of a model building using the average climatic data of the city of Casablanca (Morocco). For this study, we used the dynamic thermal simulation tool “TRNSYS 16” which predicts the thermal behavior of building and systems associated with it. Using this software, we evaluated the effect of the above material wastes on thermal comfort and building energy consumption. The type and the thickness of the materials were considered as variants to choose the better solution. The average temperatures of building supposed thermally insulated compared to those obtained without insulation clearly show the thermal insulation ability of tested materials during the cold and warm periods of the year. Increasing the thickness of the insulator makes locals increasingly comfortable. Because of their performance, leather and carpentry wastes can compete with conventional insulating materials such as polystyrene and cork.  相似文献   
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7.
A boronic acid-based anthracene fluorescent probe was functionalised with an acrylamide unit to incorporate into a hydrogel system for monosaccharide detection. In solution, the fluorescent probe displayed a strong fluorescence turn-on response upon exposure to fructose, and an expected trend in apparent binding constants, as judged by a fluorescence response where D-fructose>D-galactose>D-mannose>D-glucose. The hydrogel incorporating the boronic acid monomer demonstrated the ability to detect monosaccharides by fluorescence with the same overall trend as the monomer in solution with the addition of D-fructose resulting in a 10-fold enhancement (≤0.25 mol/L).  相似文献   
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9.
We investigate the achievable rate of receive antenna selection MIMO systems in the presence of mutual coupling and spatial correlation. For that, we assume the antenna array to consist of dipole antennas placed side-by-side in a linear pattern and in a very limited physical space. In a first step, we will assume perfect channel state information at the receiver side only and a negligible training overhead compared with the payload. We will demonstrate that in contrast to what might be expected based on results for cases without mutual coupling, MIMO receive antenna selection can achieve higher data rates than the system using all antennas provided that the total number of receive antennas is larger than a critical value that we will further discuss. We then propose an optimal antenna selection processing that ensures rate maximization regardless of the number of antennas used. In a later step, we will address the impact of training overhead on the system achievable rate when the training overhead is considerable. We will show that such a rate is reduced dramatically due to the large amount of training overhead arising from the presence of mutual coupling. To overcome this problem, we will thus propose a novel channel estimation method, which reduces the training overhead greatly and improves the system achievable rate performance.  相似文献   
10.
The fractionated crystallization of high density polyethylene dispersed in a poly(ethylene terephthalate) matrix at composition of 15 wt-% was studied. The effect of the molecular weight of polyethylene with and without compatibilization was particularly addressed regarding its influence on the morphology of the blends. For non-compatibilized blends, the dramatic influence of the molecular weight of the polyethylene on the viscosity ratio and therefore on the dispersion is reflected on the relative intensities of the twin crystallization peaks of polyethylene that are developed upon cooling. These peaks reflect two sets of particles that are nucleated by more or less active heterogeneities. The influence of the addition of an ethylene-glycidyl methacrylate copolymer on the morphology and on the crystallization of the blends was also investigated. For a high molecular weight polyethylene, the compatibilizer shows less efficiency as far as dispersion is concerned.  相似文献   
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