REDUCED COMPLEXITY FREQUENCY ESTIMATOR FOR BURST TRANSMISSION

In burst transmission, carrier recovery is a critical point for synchronization systems. With a feedforward carrier phase recovery algorithm, a small frequency offset can significantly increase the cycle slip rate and then the phase error variance. Therefore, in order to obtain an accurate carrier phase estimation, a precise frequency correction is required. For M-states phase shift keying (M-PSK) modulated signals an unbiased feedforward reduced complexity frequency estimator (RCFE), operating in the non-data aided mode (NDA) is derived from the maximum likelihood (ML) principle. A compromise is realized between noise filtering and estimation slip probability by minimizing the estimator variance. It is optimized to operate at a low signal-to-noise ratio and short bursts. Its performance is compared to that of the ML estimator. The estimator is applied to an all-feedforward synchronization structure with QPSK modulated signals. Global performance of the modem synchronization structure is supplied. © 1996 by John Wiley & Sons, Ltd.     

带效率修正的无级变速器速比控制研究

针对无级变速器速比控制问题,在分析了占传动系统损失大部分的CVT效率损失基础上,根据其效率损失模型,具体给出了参数确定步骤,并对传统目标速比在效率补偿的基础上进行了修正,最后制定了金属带式无级变速器和发动机的匹配控制策略,得出补偿效率后的整车最大传动效率的速比控制策略;搭建了CVT硬件在环仿真平台对该策略进行了验证,最后进行了实车测试.结果表明该策略能够提高CVT和发动机的整体传动效率,改善了动力性和燃油经济性.     

超高压电网线路距离保护延时段整定计算

按照逐级逐段配合原则整定超高压电网线路距离保护Ⅱ段会因多级同段配合而导致动作时延过长,这在线路故障主保护拒动时将严重威胁系统安全.提出了一种距离保护延时段整定计算方案,方案中距离保护Ⅱ段只与相邻线路纵联保护配合,若不能满足灵敏度要求,则采用灵敏度调整函数适当提高灵敏度使其能够反应本线路绝大部分故障,同时增加距离保护Ⅱ段延时以确保选择性;并从灵敏度补充的角度将距离保护Ⅲ段当成传统的距离保护Ⅱ段使用,由其确保灵敏度满足规程要求.算例分析表明了该整定方案能够保证距离保护的选择性和灵敏性,并能兼顾速动性,配合逻辑简洁,方便程序实现.     

在动态测量中面阵CCD受控变速读出方法研究

在成象跟踪系统中，光电探测的帧频对于系统的性能有着直接的影响。本文根据ＣＣＤ输出图象信号的电学特征，提出了变速读出的工作原理和技术途径，完成了有关电路的设计。通过实验证明了变速读出方法是提高面阵ＣＣＤ帧频的一种有效途径。     

光电对抗用激光器技术

激光器技术在最近几年发展迅猛,各种规格的激光源是各种军民两用光电设备的关键部件之一.在定向能激光武器中,不断进步的激光器技术大大提高了系统的作战效果,如提高了作战距离和打击精度.现代固体激光器技术由于具有较高的光电转换效率和较小的重量体积,已经成为了光电对抗用的理想光源.然而,任何系统的最终性能还受不同子系统相互配合的...     

Dynamic Aspects of Stimulus-Response Correspondence: Evidence for Two Mechanisms Involved in the Simon Effect.

It has been recently proposed that the time course of the Simon effect may vary across tasks, which might reflect different types of stimulus-response (S-R) transmissions (E. Wascher, U. Schatz, T. Kuder, & R. Verleger, 2001). The authors tested this notion in 4 experiments by comparing Simon effects evoked by horizontal and vertical S-R arrangements. The temporal properties of the effect, as well as lateralized readiness potential-difference waves, indicated a fast and transient influence of the horizontal, but a slow and sustained influence of the vertical spatial stimulus feature on performance. Additional evidence for this temporal dissociation was obtained in experiments that induced a shortening or lengthening of the mean response time. Thus, the data strongly indicate that there are 2 temporally dissociable mechanisms involved in generating the Simon effect for horizontal and vertical S-R relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

履带式推土机电液转向系统及舒适性研究

履带推土机作业环境恶劣,为降低驾驶员的工作劳动强度,对推土机操作舒适性、转向方便灵活等要求越来越高。良好的转向操作性能可以减轻驾驶员的劳动强度,同时也影响着履带车辆转向行驶的机动性、准确性。差速转向机构应用于履带式推土机,提高了转向性能及操作舒适性。尤其,随着电液比例控制技术的发展及液压元件的成熟,自动化、机电液一体化技术的广泛应用,大大提高了转向操纵的舒适性,成为履带推土机转向控制系统的发展趋势。因此,履带车辆的操纵舒适性是当前重点研究方向之一。     

Kinematic and Dynamic Analyses of the Tripode Joint

This paper is concerned with an application of multibody techniques to the dynamic analysis of the tripode joint. The purpose of the mathematical model developed is the computation of all the constraint forces. In fact, the results of this investigation are preliminary for a study on the influence of geometry and inertia design parameters on the noise and vibrations caused by the joint.     

VB与Auto CAD间的数据交换及其在齿轮传动中的应用

介绍了用Visual Basic语言编程设计齿轮传动并与Auto CAD作动态数据交换自动生成图形的软件系统,同时还给出了程序设计过程中参数选择与导入的方法.     

Millimeter-Wave Concurrent Beamforming: A Multi-Player Multi-Armed Bandit Approach

The communication in the Millimeter-wave (mmWave) band, i.e., 30~300 GHz, is characterized by short-range transmissions and the use of antenna beamforming (BF). Thus, multiple mmWave access points (APs) should be installed to fully cover a target environment with gigabits per second (Gbps) connectivity. However, inter-beam interference prevents maximizing the sum rates of the established concurrent links. In this paper, a reinforcement learning (RL) approach is proposed for enabling mmWave concurrent transmissions by finding out beam directions that maximize the long-term average sum rates of the concurrent links. Specifically, the problem is formulated as a multiplayer multiarmed bandit (MAB), where mmWave APs act as the players aiming to maximize their achievable rewards, i.e., data rates, and the arms to play are the available beam directions. In this setup, a selfish concurrent multiplayer MAB strategy is advocated. Four different MAB algorithms, namely, ϵ-greedy, upper confidence bound (UCB), Thompson sampling (TS), and exponential weight algorithm for exploration and exploitation (EXP3) are examined by employing them in each AP to selfishly enhance its beam selection based only on its previous observations. After a few rounds of interactions, mmWave APs learn how to select concurrent beams that enhance the overall system performance. The proposed MAB based mmWave concurrent BF shows comparable performance to the optimal solution.