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排序方式: 共有498条查询结果,搜索用时 15 毫秒
1.
Vologiannidis Stavros Antoniou Efstathios 《Multidimensional Systems and Signal Processing》2021,32(2):559-572
Multidimensional Systems and Signal Processing - In this paper we present new methods for the reduction of a polynomial system matrix describing a discrete linear repetitive process, to equivalent... 相似文献
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A near-optimal multiuser detector for DS-CDMA systems using semidefinite programming relaxation 总被引:1,自引:0,他引:1
A multiuser detector for direct-sequence code-division multiple-access systems based on semidefinite programming (SDP) is proposed. It is shown that maximum likelihood (ML) detection can be carried out by "relaxing" the associated integer programming problem to a dual SDP problem, which leads to a detector of polynomial complexity. Computer simulations that demonstrate that the proposed detector offers near-optimal performance with considerably reduced computational complexity compared with that of existing primal-SDP-relaxation based detectors are presented. 相似文献
4.
Constantinos Simserides 《Journal of Computational Electronics》2003,2(2-4):459-463
We analyze the important changes induced to the density of states (DOS) of a quasi two-dimensional-electron-gas (2DEG), when it is subjected to an in-plane magnetic field, B. The DOS diverges significantly from the famous step-like form and this introduces changes to the pertinent electronic properties. In order to calculate the DOS it is indispensable to use a self-consistent approach. The eigenvalue problem has to be solved for each subband index i and in-plane wavevector, k x, when the quasi 2DEG is parallel to the xy-plane and B is applied along the y-axis. Although the modification of the DOS is usually ignored, we show here that not only the general shape of the DOS varies, but this effect is also quantitative. 相似文献
5.
M D'Silva D Candinas S Lee O Achilleos P Bonnet E Antoniou D Mayer P McMaster 《Canadian Metallurgical Quarterly》1995,8(4):298-306
The purpose of this study was to develop a microsurgical cluster model of heart plus entire thoracic aorta transplantation and to compare it to the isolated model of heart transplantation as a tool to study transplant rejection. Thirty-six syngeneic (DA x DA and Lew x Lew) and allogeneic (DA x PVG and DA x Lew) cluster heart-aorta transplants were compared to 43 syngeneic and allogeneic isolated heart grafts. Graft survival, recipient survival and histological data on myocardial and aortic tissues were assessed. There was no statistically significant difference in graft survival between the two models studied (P > 0.05). In the cluster transplants, the aortic component was spared the severity of acute rejection noted for the myocardial counterpart. In conclusion, the results demonstrated that the cluster model was technically feasible and highly reproducible. Additionally, it was possible to apply this model to the study of experimental allograft rejection using novel immunosuppressants. The success of the cluster model in strongly mismatched transplant strain combinations underscores its potential for application in slower rejection combinations, making it particularly suited for chronic rejection studies. The inherent capacity for sampling a broader range of vessel sizes in one animal makes the cluster model more suitable than the isolated models of aorta or heart for application to experimental protocols. 相似文献
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Double-hydrophilic poly[(oligo(ethylene glycol) methacrylate)-co-methyl methacrylate]-b-poly(2-(diethylamino)ethyl methacrylate), P(EGMA-co-MMA)-b-PDEA, diblock terpolymers were designed and explored in aqueous media. Thanks to the thermosensitivity of the P(EGMA-co-MMA) statistical block and the pH sensitivity of the PDEA block, these terpolymers form two distinct micellar self-assemblies at different conditions of pH and temperature. The thermosensitivity of these terpolymers can be tuned by controlling the LCST of the statistical block through its monomer unit composition. 相似文献
8.
George G. Olympiou Christos M. Kalamaras Constantinos D. Zeinalipour-Yazdi Angelos M. Efstathiou 《Catalysis Today》2007,127(1-4):304-318
Steady-state isotopic transient kinetic analysis (SSITKA) experiments coupled with mass spectrometry were performed for the first time to study essential mechanistic aspects of the water–gas shift (WGS) reaction over alumina-supported Pt, Pd, and Rh catalysts. In particular, the concentrations (μmol g−1) of active intermediate species found in the carbon-path from CO to the CO2 product gas (use of 13CO), and in the hydrogen-path from H2O to the H2 product gas (use of D2O) of the reaction mechanism were determined. It was found that by increasing the reaction temperature from 350 to 500 °C the concentration of active species in both the carbon-path and hydrogen-path increased significantly. Based on the large concentration of active species present in the hydrogen-path (OH/H located on the alumina support), the latter being larger than six equivalent monolayers based on the exposed noble metal surface area (θ > 6.0), the small concentration of OH groups along the periphery of metal-support interface, and the significantly smaller concentration (μmol g−1) of active species present in the carbon-path (adsorbed CO on the noble metal and COOH species on the alumina support and/or the metal-support interface), it might be suggested that diffusion of OH/H species on the alumina support towards catalytic sites present in the hydrogen-path of reaction mechanism might be considered as a slow reaction step. The formation of labile OH/H species is the result of dissociative chemisorption of water on the alumina support, where the role of noble metal is to activate the CO chemisorption and likely to promote formate decomposition into CO2 and H2 products. It was found that there is a good correlation between the surface concentration and binding energy of CO on the noble metal (Pt, Pd or Rh) with the activity of alumina-supported noble metal towards the WGS reaction. 相似文献
9.
Viscosimetric measurements were obtained with the ternary systems polystyrene/dioxane/methanol, polystyrene/benzene/methanol and poly(methyl methacrylate)/dioxane/cyclohexane, changing the solvent mixture composition at constant temperature. The polystyrene and poly(methyl methacrylate) systems exhibit a transition phenomenon with solvent-mixture composition in which the polymer is just above the theta condition. In the case where two theta conditions occur ((θ-intra, θ-inter) the transition point is closely related to the intramolecular theta conditions. Moreover the intramolecular theta conditions vary with the molecular weight in the region of molecular weights where the preferential adsorption also varies. This variation induces a variation of the transition point with molecular weight which obeys a formula analogous to that giving the variation of the preferential adsorption with molecular weight. 相似文献
10.
In order to overcome the difficulty of the determination of the molecular weight of a polymer in the low molecular weight region by viscometry using the Mark–Houwink–Sakurada (MHS) equation, we have proposed the Dondos–Benoit relationship [η]?1 = A2 + AM?1/2, for a number of polymer–solvent systems, for which we give the numerical values of the parameters A1 and A2. Furthermore, we suggest a method for the determination of the above parameters using the MHS constants a and k. 相似文献