阀控式密封铅酸蓄电池与固定型防酸隔爆式铅酸蓄电池的性能比较

对阀控式密封铅酸蓄电池（简称ＶＲＬＡ电池）与传统的固定型防酸隔爆式铅酸蓄电池（简称ＧＧＦ电池）的性能，特点等进行了比较，并对在确保通信安全的前提下，选择哪种蓄电池较为合适提出了建议。     

可充电电池

<正> 可充电电池主要有铅酸蓄电池和碱性蓄电他两种。目前使用的镍镉(NiCd)、镍氢(NiMH)和锂离子(Li-Ion)电池都是碱性电池。 铅酸电池 阀控式免维护铅酸电池的基本结构如图1所示。它由正负极板、隔板、电解液、安全阀、气塞、外壳等部分组成。正极板上的活性物质是二氧化铅(PbO_2),负极板上的活性物质为海绵状纯铅(Pb)。电     

阀控密封铅酸蓄电池的使用和维护

本文通过对阀控式密封铅酸蓄电池特性的分析,讨论了阀控铅酸电池在实际工作中的正确使用和维护保养方法。     

地铁通信阀控式铅酸蓄电池的维护与性能评估

阐述了从地铁建设到运营期间针对阀控式密封铅酸蓄电池需要注意的问题,总结了在使用过程中常见的故障,介绍了其日常维护措施与年度保养内容。同时,针对阀控式密封铅酸蓄电池的渐变失效现象,提出性能预判评估的方法,以及单个蓄电池或蓄电池组更换的参考标准。     

影响蓄电池寿命的因素分析

本文主要分析了阀控密封式铅酸电池和干荷式铅酸蓄电池使用寿命的影响因素,在使用性能方面的优缺点和适用情况,并提出了在平时的使用中如何做好维护工作来减免不利因素造成的伤害,以延长蓄电池的使用寿命.     

阀控式铅酸蓄电池的最佳充电方法

阀控式铅酸蓄电池的最佳充电方法西安通信学院王鸿麟近年来，阀控式铅酸蓄电池在电源中应用得逐渐多起来。由于阀控式蓄电池的充电与以往的充电要求不尽相同，所以传统的充电方法不能适应，以致使电池的寿命受到影响。实践证明，阀控式铅酸蓄电池的浮充电压偏差５％，电池...     

阀控式铅酸蓄电池提前失效原因分析及对策

在实际使用中,许多VRLA蓄电池远未达到设计寿命就提前失效报废了,原因除了电池本身的质量问题,关键在于能否正确地使用、维护VRLA蓄电池。文中探讨了阀控式铅酸蓄电池失效的常见原因,在实践的基础上总结了正确的使用方法和维护手段,延长了蓄电池的循环寿命。     

后备式UPS中阀控式铅酸蓄电池的使用

后备式ＵＰＳ中阀控式铅酸蓄电池的使用贺亮目前，在返修的ＵＰＳ电源中，大约有１／４～１／３是由蓄电池故障引起的。在中小型ＵＰＳ电源中，广泛使用着阀控式铅酸蓄电池（俗称免维护电池）。这种蓄电池采用了先进的阴极吸收式密封技术，但其价格比较贵，一般占ＵＰＳ电...     

通信阀控式铅酸蓄电池的使用及维护

文章主要就阀控式密封铅酸蓄电池（简称VRLA）在电力通信系统使用中应注意的问题作了探讨,并结合实际工作经验,提出了一些对VRLA电池维护方面的建议。     

阀控式密封铅酸蓄电池连接方式的探讨

随着通信事业的发展,阀控式密封铅酸蓄电池(以下简称密封电池)应运而生。其以体积小,可多方向放置,不须初充电,运输安装方便,运行中无酸雾逸出,可以安装于通信机房,无需添加蒸馏水,运行中维护工作量小,适于远程监控等优点,因而倍受青睐。密封电池在国外兴起于70年代     

应变SiGe沟道PMOSFET亚阈值特性模拟

通过简化的模型,对应变SiGe沟道PMOSFET及Si PMOSFET的亚阈值特性作出了简单的理论分析,然后用二维模拟器Medici进行了模拟和对比;研究了截止电流和亚阈值斜率随SiGe PMOSFET垂直结构参数的变化关系。模拟结果同理论分析符合一致,表明应变SiGe沟道PMOSFET的亚阈值特性比Si PMOSFET更差,并且对垂直结构参数敏感,在器件设计时值得关注。     

背景风场和温度梯度对重力波传播的影响

运用射线跟踪方法，计算了背景风场和温度梯度共同影响下大气重力波的传播射线，结果表明，在顺风传播情况下，较小波长的重力波在１００ｋｍ左右的高度上被捕获，较大波长时可穿透传播到热层，但射线在水平方向拉伸；在逆风传播情况下，较长波长的波在１２０ｋｍ之下的高度发生无环反射，较短波长的波在２００ｋｍ以上的高度发生有环反射，而介于两种反射波的波长之间的波则穿透传播到热层高度，射线变陡。分析表明，上述波的反射、     

Characterization of special fibers and fiber devices

Methods for characterizing birefringent fibers (both those with high circular or linear birefringence and those with negligible intrinsic birefringence) are presented, and their relative merits are discussed. Fibers with high nonlinear coefficients exhibit interesting optical phenomena, and methods are developed to determine second harmonic, Pockels and Kerr effects, parametric phenomena, and the Verdet constant of silica and higher-loss, nonsilica fibers. Fibers containing rare-earth ions are of interest both as active (laser and amplifiers) and passive systems. Techniques are developed to characterize these devices, and conventional methods are modified to quantify dopant parameters within the fiber. Techniques for the measurement of the diverse properties of all these different fibers are presented with results, and, where appropriate, the problems with their characterization are discussed     

Experimental identification of inertial and friction parameters for electro-hydraulic motion simulators

The fullness of dynamics equations and the degree of uncertainty in dynamic parameters are important factors in application of the identified models to model-based control strategies. Therefore, in this paper, the experimental identification of inertial parameters and friction coefficients are dealt with for an electro-hydraulic motion simulator, normally consisting of the Stewart platform. The model with arbitrary geometry, inertia distribution and frictions are obtained based on a structured Boltzmann-Hamel-d’Alembert formulation, and then the estimation equations are explicitly expressed in terms of a linear form with respect to the base parameters of minimal dimension to be identified. The identified parameters are obtained through solving the estimation equations by simple least square method. Moreover, exciting trajectories are also designed respectively in the actuating space and task space. Finally, the identified parameters are used to validate the developed model by comparing the predicted forces with respect to the actuating forces for a random trajectory.     

Large-area oxidation of AlAs layers for dielectric stacks and thick buried oxides

The wet oxidation of AlAs and AlGaAs has been limited to relatively small lateral dimensions and relatively thin layers. Approaches are described to extend the oxide dimensions both horizontally and vertically, creating large-area and thick buried oxides. Two types of large-area structures are examined: dielectric stacks with thin buried oxides and semiconductor-on-insulator structures with thick buried oxides. Low Al-content AlGaAs layers with low oxidation rates are used as the high-index layers in large-area dielectric-stack structures. High Al-content AlGaAs layers with low volume contraction are used to create stable, thick buried oxides with millimeter-scale areas.     

Multi-user receivers for a multiple-access system based on chaotic sequences on unknown asynchronous frequency-selective channels

This article deals with the problem of multi-user detection for a chaos-based multiple-access system, using a Differential Chaos Shift Keying (DCSK) modulation. The transmission channels are frequency-selective (multipath), and the channel characteristics (gains and delays) are unknown at the receiver side. It is only assumed that estimates of the minimum and maximum delays are available, only for the channel corresponding to the user of interest. Under such assumptions, a least-mean-square detector is derived, whose theoretical performances are provided. This detector is compared with the detector obtained when the delays are known, and with the LMMSE detector, for which all system parameters are available. The theoretical analysis is confirmed by the simulation results, which show that the LMS detector is not dramatically degraded with respect to the LMMSE detector, and that it is quite robust with respect to poor accuracy of the delay estimation.     

Polyphase Barker sequences

Polyphase sequences are time-discrete complex sequences with constant magnitude and variable phase. In this letter polyphase sequences with aperiodic autocorrelation function (ACF) sidelobes of values less than or equal to 1 are presented. Such sequences are called Barker sequences. Binary Barker sequences with elements 1 or -1 are only known up to 13 elements. Now, with an iteration scheme, polyphase Barker sequences are found up to 25 elements, except for 20 elements.<>     

利用星载激光雷达研究中国海及其周边海域的云层分布

利用2007~2010年4年间的CALIPSO 5 km二级云数据对中国海及其周边海域层数不同的云的出现概率（COF）随年度、月份和区域的变化进行了统计分析,并将2007年、2008年的部分统计结果与MODIS数据的统计结果相比较。结果表明：在研究区域,不同年份的层数相同的云的出现概率差别小于3%,且不同年份的出现概率区域分布相近,在靠近赤道的海域高于80%,在20°N附近海域低于50%,这与MODIS数据的统计结果相一致;同一年不同月份的出现概率差异明显,但是4年都是在6、7月出现最大值,层数相同的云的出现概率随纬度变化而明显变化。     

海量超声数据体可视化研究

近年来,随着科学数据的快速增长,海量数据的可视化分析成了急需解决的难题.越来越多的处理海量数据的方法向着并行、分布式处理的方向发展.本文提出了一种混合的框架来处理海量的超声数据,该框架通过整合多种硬件环境和计算资源来处理海量数据;所有的数据都存放在一个基于高速网络环境的数据共享中心,具有高性能显卡的前端工作站将耗时的处理任务分配到网络中的计算结点,而自身处理显示和交互的操作;同时基于OpenCL和OpenMP实现了可视化算法在GPU和CPU上的并行计算;核外算法应用在本框架中来处理海量的体数据.实验结果表明,本文提出的框架不仅可以处理海量数据,而且具有较高的交互性能.     

Control aspects of intraaortic balloon pumping: an overview

Temporary or permanent, internal or external, in-series or bypass cardiac assist devices are examined with emphasis on intraaortic balloon pumping. Physiological and clinical consequences of the medical assistance are discussed. Major advantages of the devices are to provide adequate perfusion and, secondarily, to unload the heart and to reduce oxygen consumption of the failing myocardium. Major problems with the cardiac assist devices are related to synchronization with the natural heart, or proper timing, and to the determination of suitable control variables. Optimization algorithms based on the selected performance criteria and computer-based automatic controls are instituted to overcome some of these shortcomings. Finally schemes of automatic control of implantable assist devices are discussed