行波微流体驱动技术研究

通过对行波及声流产生机理的研究,得出微管中的流体产生与行波同方向的声流.利用FPW(flexural plate wave)装置进行了跟踪、染色试验,验证了超声行波对微流体驱动的可行性.作为一种新型微流体驱动技术,行波微流体驱动能很好的弥补现有驱动和控制技术的不足.     

配电网馈线终端保护装置的研制

为提高配电网的供电可靠性,防止用户侧的事故波及配电网,从而造成其它用户不必要的停电,提出了一种配电网的馈线终端保护。根据对配电网用户侧波及事故的统计分析,得出该保护应具有过电流储能跳闸和零序接地保护的动作特性。利用成熟的软、硬件技术,合理设计保护装置的结构,使该保护的抗干扰能力、可靠性等得到了较大的提高,很好地满足了配电网的特殊要求。同时根据装置的特殊要求在设计中采用了各种新技术如:利用MEMS工艺的压力传感器来检测SF6开关压力,并通过改进的4~20mA的电流变换回路来传输压力信号;利用超级电容器组替代传统的蓄电池作为备用电源等。目前装置已投入试运行,满足预期的各种功能,状态良好。     

Predictive call admission control for multimedia streaming in CDMA cellular environments

Third-generation (3G) wireless networks based on code-division multiple access (CDMA) have been engineered to provide mobile users with voice as well as advanced packet data services. Support of Internet-based multimedia streaming services is considered a critical factor for future deployment of such networks. Provisioning streaming services in a dependable way, however, requires supporting data transmission at relatively high data rates while maintaining session quality during both intracell and intercell user movements. In this paper, an adaptive bandwidth allocation and admission control scheme is proposed for managing network resources for a streaming service. Streaming requests are assumed to be served by an adaptive server capable of choosing suitable video streaming parameters (e.g., video resolution, frame rate, and encoding parameters) in response to possible requests from the wireless network to vary the currently allocated bandwidth. The devised admission control scheme exploits a priori knowledge of user mobility patterns to minimize the risk of running into an overload condition after acceptance of a new multimedia streaming connection. The obtained simulation results show that, compared to a nonpredictive admission control scheme, the proposed scheme achieves a lower forced-termination probability and higher throughput, while consuming less base-station transmission energy.     

北京市终端能源消费结构特点分析

以1997-2006年北京市终端能源消费为例,从时间角度对不同产业部门能源消费变化及能源消费结构进行了深入分析,总结了不同产业终端能源消费结构的变化特点,为调整北京市终端能源消费结构、节能降耗提出了初步的建议。     

基于大数据平台的电压质量诊断与应用分析

针对传统电压质量异常识别方法效率低下,难以做到全面的识别与监控的问题。文中搭建了电压质量诊断与分析平台模型,通过主成分分析得到影响端用户电压监测分析、配网低压台区运行状态分析等应用的主成分,对数据进行降维,实现数据的简化处理。聚类分析筛选出符合异常特征的电压异常数据,利用电压异常模型确定异常数据,生成电压异常识别结果。基于J2EE技术框架在末端用户电压监测分析、配网低压台区运行状态分析、配网线路故障判断分析等方面进行可视化展示。     

智能电网促进了低压电器新品种的发展与新技术的应用

智能电网对配电和终端用户提出一系列要求,包括能接入各种分布式电源、保证电能质量和用电安全、自适应的故障处理能力等,这些要求促进了低压电器新品种的发展。为了保证低压配电线路供电的连续性和可靠性,从低压选择性断路器的发展和智能断路器的状态检测等方面介绍低压电器的发展。     

Enhanced soft-handoff scheme for real-time streaming services in intelligent transportation systems based on CDMA

Code division multiple access (CDMA)-based radio-on-fiber road-vehicle communication systems were proposed to support real-time streaming services in intelligent transportation systems (ITSs). Soft handoff should be provided for real-time streaming services because these services are required to guarantee real-time property and quality of service (QoS). However, soft handoff of real-time streaming services causes the shortage of resource in view of the system. In this paper, the double-adjustment soft-handoff (DASH) scheme is proposed to support seamless service regardless of the shortage of resource and maximize the resource efficiency when real-time streaming services are served in CDMA-based ITSs. The DASH scheme adjusts the data rate of a call when it starts and finishes soft handoff. The performance of the DASH scheme is evaluated by analytical and simulation methods. Performances are evaluated with respect to the blocking probability, the handoff failure probability, and the carried traffic. Numerical results show that the proposed scheme can give relative good maintenance of calls and good throughput.     

语音质量客观评价方法的研究

语音质量评价是语音处理系统研发中的重要问题,因此有必要对日益庞杂的语音系统进行测评。文章阐述了语音质量客观评价方法在语音通信技术中的作用,介绍了语音质量的2种客观评价方法,对当前主要语音质量客观评价方法的分类进行了说明,并就未来的研究方向提出了建议。     

顺序流媒体缓存系统的设计与实现

流媒体数据消耗大量的网络带宽,其中很大一部分是因为热门资源的重复传输,鉴于此情况设计一种顺序流媒体缓存系统,减少不必要的传输.该设计基于代理服务器,针对顺序流媒体独特的存储及访问控制机制,结合代理服务器缓存模块的特征,设计并实现了可用于对顺序流媒体进行缓存的系统.测试结果表明,缓存系统很好的解决了顺序流媒体在缓存上存在的难以命中的问题,可准确的对顺序流媒体进行缓存并在后续访问中完全命中,大幅提高了缓存字节命中率.     

初探饱和黄色对于察觉阈限对比的影响

该文通过在暗室中进行的察觉阈限对比实验,对饱和黄色及无彩色的察觉阈限对比进行了研究。得到了在不同背景亮度、不同视角下黄色和非彩色目标物的察觉阈限对比值,并将两种颜色目标物的阈限对比值进行了比较,得出饱和黄色能使察觉阈限对比降低4.59%。     

Computation of Streaming Current in Oil Pipes

The calculation of steaming current in oil pipes is involved in solving the charge conservation equation. It is a nonlinear equation without accurate analytical solution under turbulent-flow condition. Based on some reasonable simplifications, an approximate analytical expression for the equation and a due formula for streaming current are derived. It is proved with experimental results that the formula can accurately predict the streaming current, thus providing a method that is able to reliably and conveniently compute streaming electrification in oil pipe.     

初探饱和黄色对于察觉阍限对此的影响

该文通过在暗室中进行的察觉阈限对比实验，对饱和黄色及无彩色的察觉阂限对比进行了研究。得到了在不同背景亮度、不同视角下黄色和非彩色目标物的察觉阈限对比值，并将两种颜色目标物的阈限对比值进行了比较，得出饱和黄色能使察觉阈限对比降低4．59％。     

dc field effects on streaming electrification in insulating oils

The results of an experimental investigation into the influence of impurities on electrification in insulating liquids in a tube model under an external dc field effect is described. Both conduction and streaming currents were measured as a function of temperature and flow rate using a paper-pressboard model with concentric cylindrical electrode geometry. Positive or negative dc voltage was applied to the inner electrode. The streaming current was measured from a shielded test chamber and the conduction current was measured from the ground electrode. Energization by positive dc voltage always enhanced the streaming electrification; however, when the applied voltage was negative, the polarity of streaming current was field strength dependent. At low fields (<0.52 kV/mm), the streaming current with negative dc field I_sn^c increased with increased field and with field strength >0.52 kV/mm, polarity reversal was observed. The field at which current crossed the zero value has been defined as the zero cross over point (ZCOP). Flow rate did not have any influence on the ZCOP; however, the additive concentration, moisture content and the temperature affected this ZCOP. In the presence of the corrosion inhibitor carbazole, the streaming current with negative dc field, I_sn attained zero at low fields. The conduction currents corresponding to fields where streaming currents were zero were also relatively low. It is therefore possible that by applying a moderate dc field of appropriate polarity the streaming current can be reduced to very low values by adjusting the carbazole concentration in the test liquid     

Flow electrification of transformer oil effects of mixed fields

Static electrification in transformer oil is investigated experimentally using a laboratory synthetic closed cycle, where the oil is pumped in a coaxial electrode arrangement. The electrode system is electrically energized radially with dc and/or ac, and the electrostatic charging tendency (ECT) of the oil is quantified by measuring the streaming current. The results indicate that for the same voltage ratio (K=Vˆ/(Vˆ+V)), increasing the ac or the dc voltage component leads to higher ECT of oil, although the ECT under only ac field is much lower than that under dc field. The unenergized streaming current is inherently affected by the electrode material and configuration; where electrodes having a lower work function give higher positive ECT of oil at high temperature. The energized streaming current increases with oil temperature, oil velocity and electric field; where negative dc voltage application to the outer electrode gives both higher conduction and streaming currents. While the conduction current decreases with oil velocity, increasing the frequency of mixed ac voltage has no significant effect on streaming current. Moreover, the effect of combined radial electric (ac or dc) and axial magnetic (ac or dc) fields on ECT of oil is investigated, and the results reveal that the ECT is enhanced by the magnetic field while the radial conduction current decreases. Derived formulas for the streaming current for unenergized and ac energized cases are also presented together with expressions of the volume and surface charge densities for the coaxial electrode system     

合理选择煤粉细度是降低发电综合成本重要措施

针对太仓港环保发电有限公司供煤形势紧张导致实际入炉燃煤偏离设计煤种的客观情况,对1、2号炉燃用东北煤种进行了燃烧特性试验,认为不同煤种(煤质)应选择合适的煤粉细度,才能降低飞灰含碳量,提高锅炉效率,降低燃煤损失,从而降低发电综合成本。     

基于RED5无人机直播系统的设计与实现

为了解决无人机航拍视频实时传输且可随时随地浏览的问题,分析提出一种基于RED5流媒体服务器的无人机视频直播系统设计解决方案。研究分析了流媒体技术、RTMP协议、RED5流媒体服务器、H264视频格式。实现无人机航拍采集到的视频用x264编码方式通过3G/4G模块传到流媒体服务器,经客户端请求,进行实时直播或点播功能,通过Web服务器保存视频等信息,实现视频信息管理功能。实验结果表明,该系统在现有的网络条件下具有良好的流畅性稳定性,该设计可行,系统实用可靠。     

我国电力系统终端用户的无功管理与电价

电力系统无功功率就地平衡, 是减少无功输送过程中产生损耗最有效的技术措施之一。目前我国电网中无功功率补偿的布局不够合理, 没有做到真正意义上的无功就地平衡, 造成巨大损失。在当前市场经济的环境下, 除了采用先进的技术和管理之外, 还可采取新的电价形成机制, 例如视在功率电价体制, 以调动用户安装和管理好无功功率补偿装置的积极性, 提高终端用户的功率因数。这有利于减少全系统损耗和提高系统电压质量。     

移动网络下流媒体传输拥塞控制机制的研究

在移动网络环境下,实现流媒体数据的传输已经得到非常广泛的应用。由于经典的TCP友好速率控制机制,在网络发生拥塞时,将无线误码丢包误认为拥塞丢包,会降低网络传输速率,导致网络利用率过度降低。如何保证移动网络环境下流媒体发送端正确区分拥塞丢包和无线链路丢包,实现网络传输速率的准确调整是个很重要的研究课题。本文分析了TFRC协议以及AIMD等拥塞控制机制在该数据传输问题中的适用性,提出了在TFRC协议基础上的一种改进的M TFRC协议,添加了丢包区分算法,可以准确区分丢包类型。通过NS2分析仿真,验证了M TFRC相比TFRC提高了网络吞吐量,维持较高的网络利用率,从而保证移动网络环境下流媒体服务质量。     

A Framework for Evaluation of Advanced Direct Load Control With Minimum Disruption

The advent of advanced sensor technology and the breakthroughs in telecommunication open up several new possibilities for demand-side management. More recently, there has been greater interest from utilities as well as system operators in utilizing load as a system resource through the application of new technologies. With the wider application of demand-side management, there is an increasing emphasis on control of loads with minimum disruption. This paper develops a new framework for designing as well as assessing such an advanced direct load control program with the objective of minimizing end-user discomfort and is formulated as an optimization problem. With a fairly general setup for demand-side management, a simulation-based framework is developed for the stochastic optimization problem. Next, using this framework, insights into the effect of different parameters and constraints in the model on load control are developed.      

用多参数研究变压器油的热老化

以常用的老化参数（介质损耗因数、酸值、电导率、表面张力）和油流带电电荷密度这个新参数研究变压器油的热老化。试验结果表明,这些参数与油的热老化程度有很大的关系。而且油流带电电荷密度与介质损耗因数和电导率有一定的相关性。