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41.
Power and bandwidth-efficient multilevel coding matched to noncoherent transmission with multiple-symbol differential detection is discussed. A simplified metric calculation is proposed, which has a computational complexity comparable to conventional differential detection, but offers almost the entire performance gain provided by multiple-symbol differential detection 相似文献
42.
Cliff Kuang 《城市环境设计》2009,(7):8-10
已经很少有建筑师像Will Alsop一样,如此致力于这种不同寻常的设计美学。更少有人能如此成功地实现自己的设计。马上建设完成的“芯片”大厦的设计灵感就是来自于堆积的薯条;而这个安大略艺术设计学院的扩建部分在最近一段时期的建筑中是最奇怪、最令人兴奋的。Will Alsop(1947年11月12日生)是一位出生在伦敦的英国建筑师。他对大部分出现在英国的一些独特的和有争议的现代建筑负有责任。AlsopA9建筑经常因其充满活力的色彩运用和不一般的形式而显得非同寻常。 相似文献
43.
A single-loop linear periodic system with time delay is considered. Using the mathematical tool of integral Fredholm equations
of the second kind, a characteristic function is constructed, the roots of which are inverses of the multipliers of the system.
Rigorous sufficient stability conditions are given, which are based on approximate representation of the characteristic function
in the form of a polynomial. 相似文献
44.
Basin and petroleum systems modelling is a powerful tool in petroleum exploration, but uncertainties remain in terms of the evaluation of a petroleum accumulation's size and quality, even when the petroleum system is well known and the latest modelling technology is applied. In order to interpret the results of a modelling exercise, it is necessary to understand the advantages and disadvantages of the various possible approaches used to assess petroleum migration and accumulation. This paper attempts to compare the influence of different migration modelling techniques – the flowpath, Darcy “hybrid” and invasion percolation approaches – on basin‐wide mass balance calculations for a temperature‐ and pressure‐calibrated, numerical four‐dimensional basin model. The study was performed using PetroMod® software. The study area is the well‐known Jeanne d'Arc Basin located offshore Newfoundland, eastern Canada. Model predictions were verified against pre‐existing data including the quantity and quality of discovered hydrocarbons in the basin. Modelling results showed that the Darcy method produced substantially different results compared to the other migration techniques and this was due to the high accumulation efficiency. The flowpath method, and a combination of flowpath and Darcy methods (referred to as the “hybrid” method) yielded similar results; furthermore, the hybrid method predicted the petroleum composition quite accurately. The invasion percolation method gave similar results to the hybrid approach, but little or no variation in API and GOR across the basin was predicted. The adsorption model initially applied did not adequately reproduce the natural behaviour of source rocks with respect to petroleum expulsion efficiency. Therefore a revised model was implemented in which the adsorption capacity was reduced with increasing maturity. This revised adsorption model led to more realistic volumes of hydrocarbons being retained within the source rock. The application of this approach had only a minor impact on the volume and quality of the petroleum present in the reservoir units. 相似文献
45.
K. D. Cliff 《Journal of research of the National Institute of Standards and Technology》1990,95(2):135-138
A procedure for the calibration of instruments for the detection of 222Rn in air is described. The method is based on the alpha-spectrometric determination of the concentration in air of 218Po in the calibration chamber. The calibration chamber is described, together with the method of maintaining a high aerosol concentration. The 218Po concentration at steady state in the chamber is found to be 98% of the 222Rn concentration typically. An assessment of the sources of uncertainty in the method presented indicate that the 222Rn concentration in the chamber can be determined with an overall uncertainty of about 7% at the 95% confidence level. 相似文献
46.
A.-M. Silvester R. Schober L. Lampe 《Wireless Communications, IEEE Transactions on》2007,6(4):1208-1212
In this paper, we propose a simple orthogonal space-time block coding (OSTBC) technique for continuous-phase modulation (CPM). Although the straightforward combination of orthogonal designs (ODs) and CPM was deemed impossible in X. Zhang and M.P. Fitz (2003) G. Wang and X-G Xia (2004) we show that this is easily accomplished with a burst-based approach. In fact, using the proposed technique ODs can be combined with any CPM scheme. After an appropriate ST combining at the receiver, the same detection techniques as in case of single-antenna transmission can be applied. This is a significant advantage over previously proposed ST coding schemes for CPM. We also derive accurate approximations for the bit error rate and the frame error rate of CPM with OSTBC. Both analysis and simulations show in good agreement the excellent performance of the proposed scheme 相似文献
47.
48.
Lampe A. Schober R. Gerstacker W. Huber J. 《Selected Areas in Communications, IEEE Journal on》2002,20(2):339-350
A novel multiuser detector for direct sequence code division multiple access is proposed. The receiver performs iterated soft decision interference cancellation (ISDIC) based on multiuser interference suppression filters designed for minimization of the mean-square error. Assuming a complex modulation format, we show that the multiuser interference becomes rotationally variant in the course of the iterations. Regarding this rotational variance in the design of the multiuser interference suppression filter, the presented iterative multiuser detector achieves significant performance gains compared with conventional ISDIC employing a standard minimum mean-squared error filter which is optimum only for rotationally invariant multiuser interference 相似文献
49.
Summary A number of copolymers of methyl methacrylate and chlorophenyl methacrylates of different structure was prepared and analyzed by ultraviolet spectroscopy. It was found that the copolymer composition can be determined using a calibration curve based on mixtures of the appropriate homopolymers. The U. V. spectroscopical results are in good agreement with the chlorine analysis. 相似文献
50.