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931.
932.
Turbo码综合性能分析与Turbo编码调制 总被引:1,自引:0,他引:1
对 Turbo码的 RSC分量码、交织器、调制方式、信道以及迭代译码算法进行了综合研究与性能分析,并给出了一种基于逐比特MAP算法的Turbo编码与多元调制相结合的编码调制方式。仿真结果表明,该方案将Turbo码的高编码增益与多元调制的高频谱利用率有效地结合在一起,是一种功率和频谱高效的编码调制方式,比传统的TCM方式有更好的性能。 相似文献
933.
An integral method is investigated and developed in the current work. The effects of the parameters of inlet distortions
on the trend of downstream flow feature in compressor are simulated. Other than the drag-to-lift ratio of the blade and the
inlet incidence angle, it is found that the distorted inlet velocity is another essential parameter to control the distortion
in propagation. Based on this study, a novel critical distortion line and corresponding critical distortion factor are proposed
to express the effect of the two essential inlet parameters on the propagation of distortion, namely, the inlet incidence
angle and the distorted inlet velocity. From the viewpoint of compressor efficiency, the propagation of inlet flow distortion
is further described by a compressor critical performance and its critical characteristic. The results present a useful physical
insight to an axial flow compressor behavior and asymptotic behavior of the propagation of inlet distortion, and confirm the
active role of compressor in determining the velocity distribution when compressor responds to an inlet flow distortion.
Received: 20 December 2001 / Accepted: 21 August 2002
The authors would like to thank HQ RSAF for permission to publish this work, their financial support and encouragement. The
first author wants to acknowledge Prof. Frank Marble of California Institute of Technology, for bringing the problem to the
author's attention and for his helpful discussion. 相似文献
934.
微通道电泳芯片系统中信号识别算法的设计与实现 总被引:1,自引:0,他引:1
介绍适用于微通道电泳芯片系统的DNA测序软件的总体流程,以及其中的信号处理与识别算法。以激光诱导荧光检测系统所采集到的原始数据为源信号,以小波平滑和小波去噪为理论基础,将滤波算法和峰值识别算法综合在一起进行设计,从而使其适用于检测速度更快、样品量更少的微通道电泳芯片系统。将本算法应用于DNA片段的分离实验中,可以有效地达到滤波以及信号识别的目的。 相似文献
935.
R. Gnanamoorthy N. Rajiv K. Gopinath Y. Miyahsita Y. Mutoh 《Journal of Failure Analysis and Prevention》2002,2(4):71-75
Powder-metal-processed bearings and gears are finding increasing application because of their economical and technical advantages.
The residual pores from the sintering operatives act as lubricant pockets and dampen sound and vibration. However, porosity
also decreases the mechanical strength and reduces the life of components fabricated by powder processing relative to similar
wrought components. The rolling contact fatigue behavior of sintered and heat treated steel rollers was investigated using
a fatigue test machine designed and fabricated for that purpose. The powder-metal-processed and the wrought steel rollers
that were tested had similar composition and hardness and were mated against wrought steel rollers of high hardness. The contact
stress versus number of cycles to failure data showed that the wrought steel had a very high endurance limit under rolling
contact fatigue compared to the sintered steels investigated. Rolling contact fatigue behavior was found to depend on the
porosity present in the material. Large surface peeling failures and pitting type fatigue failures were observed in the sintered
and hardened steels, while only pitting type failures were observed in the wrought steels 相似文献
936.
A modification of the well-known water-quality model 'quality simulation along river systems'(QUASAR) is presented in order to extend its ability, so that it may be considered applicable under unsteady-flow conditions. An aggregated dead-zone travel-time parameter, based on (a) the kinematic wave velocity (celerity) of the flow wave and (b) the behaviour of the solute within so-called 'dead zones', has been incorporated into the existing model formulation. This extends the current continuously-stirred tank reactor-based model process to account for the behaviour of solute under unsteady-flow conditions. The enhanced water-quality model has been validated by application to the Colorado River. 相似文献
937.
一种连续波多站发射机及频谱分析 总被引:2,自引:2,他引:0
介绍了一种连续波多站发射机的新方案,从理论上对该机的发射频谱进行了分析,并与实际结果进行比较。理论和实际都证明该方案具有很好的交调抑制、谐波抑制和杂波抑制、相噪低等诸多优点。 相似文献
938.
通过对乙烯厂甲醇车间蒸汽转化炉炉管的材料成分、力学性能、金相组织等的分析,确定定其失效模式为高温蠕变损伤,找到造成及影响炉管失效的主要因素。并对炉管的修复以及预防提出了有效的方法及建议。 相似文献
939.
Jun‐Sik Kim Maenghyo Cho 《International journal for numerical methods in engineering》2002,55(11):1323-1343
A finite element based on the efficient higher‐order zig‐zag theory with multiple delaminations is developed. The bending part of the formulation is constructed from the concept of DKQ element. Unlike conventional elements, a developed element has its reference in the bottom surface which simplifies zig‐zag terms on formulation. Exact patch solutions are developed on elements which have the bottom reference system. The present element passes proper bending patch tests in the arbitrary mesh configurations in isotropic materials. Zig‐zag formulation is adopted to model laminated plates with multiple delaminations. To assess the accuracy and efficiency of the present element based on higher‐order zig‐zag theory with multiple delaminations, the linear buckling problem of laminated plates with multiple delaminations has been analysed. The results have been compared with three‐dimensional elasticity solutions. The present element works as an efficient tool for analysing the behaviour of the laminated composites with multiple delaminations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
940.
一族Liouville可积系及其双约束流的Hamilton系统 总被引:3,自引:0,他引:3
构造了Loop代数 A2的一个子代数,由此建立了一个3×3等谱问题,由屠规彰格式得到了一族Liouville意义下的可积Hamilton方程族。通过建立双对称约束,得到了该方程族的两组约束流,并将其化为广义Hamilton系统。 相似文献