子波理论与应用:进展与展望

子波理论被认为是傅里叶分析的重大突破,它已成为当今从应用数学到信号与图象处理等众多领域的研究热点。本文综述了子波分析这一前沿领域的发展现状,评述了它的最新进展(包括离散与连续子波变换、快速子波算法及应用),指出了这一领域研究的有关问题。     

变速运行下抽油机系统力学参数相关性分析

抽油机变速运行技术能降低电机的峰值功率,改善抽油系统的运行状况。目前在国内外各大油田试验推广,以实现抽油系统的节能降载,提高抽油机的系统效率。为了分析在变速运行过程中造成电机峰值功率降低的主要因素,将整个抽油系统划分为3个子节点,通过现场试验的方式,测取各节点的力学参数变化情况,并引入变异系数的概念,用来描述和对比各项数据的离散程度的大小。在进行数据处理时,结合统计学理论,使用SPSS软件对变化的力学参数作相关性分析,结果表明电机功率的变化与转速变化具有强相关性,电机扭矩的变化与电机的惯性扭矩同样具有强相关性,而减速箱扭矩的变化与曲柄惯性扭矩以及游梁惯性扭矩具有极弱相关性,在分析和对比悬点速度曲线时发现悬点的梯形台式平稳运行有助于降低减速箱扭矩的波动。     

Equalization issues in multicarrier transmission using filter banks

In multicarrier data transmission using filter banks, adaptive equalizers can be introduced in the receiver in every subchannel, to achieve high bit rates. Following conventional data transmission techniques, two approaches can be envisaged, namely the double sampling equalizer and the critical sampling equalizer. Both schemes are discussed and assessed in the present paper, in the multicarrier context. Estimations are given for the lengths of the equalizers as a function of the channel distortion and of the roll-off factor of the prototype filter in the receiver filter bank. The importance of the roll-off factor is stressed, since it controls the computational complexity of the system. Simulation results associated with two channel models are given to support the theoretical analysis. They show that the critical sampling approach has an advantage in computation rate over the double sampling scheme, when the prototype filter roll-off is above 0.5 and when the mean square output error is the performance criterion and no timing offset is introduced.     

氯盐腐蚀条件下钢筋混凝土结构抗力衰减模型研究

采用改进的Fick第二扩散定律来描述混凝土内氯离子的扩散过程,从而可以预测混凝土内钢筋开始锈蚀的时间;建立了均匀腐蚀、点腐蚀以及两者同时存在条件下的钢筋腐蚀速度模型,为结构抗力衷减规律的研究奠定了基础。算例表明建立的模型是合理的。     

Improved Update Step for Scalable Video Coding in Video Surveillance

Many evolving video services and applications for intelligent security systems require reliable transmission of high quality video to diverse clients over heterogeneous networks using available system resources. Scalable video coding (SVC) is one of the emerging video compression technologies with such potential capabilities. Advances in lifting-based motion-compensated temporal filtering (MCTF) have enabled highly efficient and flexible spatial, temporal, signal-to-noise ratio (SNR), and complexity scalability to be realized over a wide range of bit rates. In this paper, we present an algorithm to improve the update step of MCTF, which serves as an important informative step for the coding performance of SVC. A novel update-step algorithm, which takes advantage of the chrominance information of the video sequence and the correlation of the motion vectors (MVs) of the neighboring blocks as well as the correlation of the derived update MVs in the low-pass frames, is proposed to improve update step of MCTF by (1) computing correct update motion information, (2) generating correct amount of energy contained in the high-pass frames. Experimental results show that the proposed algorithm can significantly improve the quality of the reconstructed video sequence in visual quality.

欧IV标准的催化转化器结构耐久性验证

接近发动机排气歧管位置的催化转化器由于其最大限度地发挥了催化剂的效能,被欧IV排放标准的车辆广泛应用。本文介绍这种催化转化器的结构和试验验证过程,包括试验目的、试验方案、失效模式、试验参数的确定等等,给出了确定加速耐久性试验的循环次数方程。     

基于PLC的变频恒压变流量供水节能系统的研究与应用

针对传统供水系统能源浪费严重、自动化程度低等特点,设计开发了一种以PLC、变频器为核心构成的变频恒压变流量供水系统。介绍了该系统的节能原理、系统构成及工作原理、硬件、软件设计及系统优点,证明了变频恒压控制系统优越的技术性能和极其显著的经济效益,具有很好的推广应用价值和进一步的研究价值。     

一种基于模块的调度策略

Cache的缺失严重影响着计算机系统的运行效率.现代构件化软件架构中模块化程度越来越高,操作系统中传统的调度策略忽视任务的模块特性,若模块具有特定的代码/数据访问集合,模块间不合理的任务调度会导致严重的Cache缺失.本文提出了一种基于模块的调度策略MBS,可以尽量连续调度同一模块中的任务,尤其适应于构件化的服务系统.分析与实验结果表明,MBS可以有效减少此类系统的Cache缺失,明显提高系统性能.     

提高真丝印花绸色牢度的工艺研究

针对真丝印花绸普遍存在的水洗牢度差问题进行了研究探讨。通过实践,采用单宁—吐酒石法对真丝印花绸进行固色,提高了真丝印花绸的水洗牢度,并提出了在提高真丝印花绸色牢度方面需要注意的几个问题。     

（NixZn0.825—xCu0.170Co0.005）Fe1.90O3.85铁氧体的电磁性能

采用配方式（ＮｉｘＺｎ０．８２５－ｘＣｕ０．１７０Ｃｏ０．００５）Ｆｅ１．９０Ｏ３．８５（简称ＮｉＣｕＺｎ铁氧体）在较宽的组成范围内（ｘ＝０．２９５～０．７５０）研究了ＮｉＣｕＺｎ铁氧体的电磁性能,发现ＮｉＣｕＺｎ铁氧体的μ,Ｑ以及温度特性随Ｎｉ含量ｘ的变化与ＮｉＺｎ铁氧体有很大不同,并对产生这种现象的原因进行了初步探讨。