向家坝—上海±800kV特高压直流输电工程系统调试技术分析

对世界上输送容量最大、输电距离最长的±800 kV特高压直流输电工程"向家坝—上海特高压直流输电工程"的系统调试进行了介绍,包括系统计算分析、系统调试方案和现场调试实施计划编写以及现场系统调试情况等;对现场系统调试分阶段完成的试验项目进行了分类,对每一类试验项目的结果进行了分析,并给出了结论。对系统调试过程中的主要技术问题,特别是大负荷试验过程中发现的问题进行了详细探讨。这些问题的解决保证了特高压直流输电工程系统调试的顺利进行和工程的按期投入运行。     

大规模源网荷友好互动系统实切试验技术

简要介绍了大规模源网荷友好互动系统实切试验,提出了基于预置指令下发模式的策略验证技术,基于全局GPS时钟同步的实切试验控制指令传输时间测试技术,以及基于过零点检测和滤波算法的频率分析技术,实现了对系统控制时间、动态频率的准确测量。试验结果表明,实切试验的快速切负荷响应时间和直流闭锁故障瞬间电网频率变化满足要求,有效验证了大规模源网荷友好互动系统的功能设计的可行性。     

循环冷却水系统结垢判断和控制方法研究

判断循环水的稳定程度,并采取控制措施,可以有效降低设备结垢风险。针对以中水做补充水的循环冷却水系统,研究了国内外循环水水质判断指数,总结了调节pH值法、控制电导法、差值法等基于多参数分析的结垢控制方法,并对其特点和适用情况作了概述,提出了调节pH值,观测循环水Cl-浓缩倍数和Ca2+浓缩倍数差值(ΔB)趋势,控制"钙硬度+全碱度"上限的复合方法,并指出了未来的发展方向。     

Equalization scheme for series connected Li-ion battery pack based on drop combination strategy

为了提升飞渡电容式均衡方法的速度和效率，提出了建立电压落差的充放电组合策略，分析了落差式组合策略与常规方案的工作过程，对比了二者均衡速度的差异，将均衡电路等效为完全响应的RLC电路，通过公式推导及Matlab计算，分析了能量损失率与电路参数的关系，对比了不同充放电组合对均衡效率的影响。研究表明：落差式组合策略可显著提升飞渡电容式均衡速度，并且可以通过优化充放电组合，提升均衡效率。通过实验对所提出的方案进行了分析与验证，结果表明，该方法能有效解决电池组不均衡问题。     

场所功能的非变异性及变异性混合

场所是由场地、使用者、行为活动等三个要素构成的。相当数量的场所以功能混合的方式适应不断变化的社会生活。场所功能的混合有非变异性混合、变异性混合两种方式,两者既有共性,又有差异。正确理解场所功能混合的规律,将有助于设计人员创作出具有个性及吸引力的、新型的场所空间。     

脉冲色谱法研究醇和水在疏水多孔硅胶上的吸附行为

采用脉冲色谱法测定了140℃时疏水多孔硅胶(HPS)上C2～5醇的吸附等温线及醇和水的Henry常数。分析得出,C2～5醇的吸附等温线在醇分压小于2.5kPa时符合Freundlich模型,醇分压小于0.3kPa时符合Langmuir单分子层模型,C2～5直链醇的Henry常数随醇的沸点和碳原子数的增加呈指数性递增,支链醇与HPS表面的作用力更强;醇的Henry常数可以分解为—CH3,—CH2—,—OH基团贡献值的加和,其对数值分别为0.68,0.60,0.46,-11.42;在气相条件下,因HPS的疏水性而使水分子不易接近HPS表面;HPS对醇-醇物系的分离是由于HPS具有基团选择性的特性。     

Automatic small blend recognition from B-rep models for analysis

The recognition and suppression of small features from B-rep models play an important role in effectively generating the qualified mesh for analysis. This paper presents a new algorithm for recognizing small blends automatically for the purpose of mesh generation. The algorithm first transforms the input B-rep model into an aggregation of faces. Then, each face is judged to be a blend or not based on matching conditions. At last, the blends with larger physical sizes than a threshold value are excluded. The innovations lie in the recognition conditions and the unique calculating procedure of the blend physical size. Several examples are given to demonstrate the validity and applicability of the algorithm.     

Evaluating sensor reliability in classification problems based on evidence theory.

This paper presents a new framework for sensor reliability evaluation in classification problems based on evidence theory (or the Dempster-Shafer theory of belief functions). The evaluation is treated as a two-stage training process. First, the authors assess the static reliability from a training set by comparing the sensor classification readings with the actual values of data, which are both represented by belief functions. Information content contained in the actual values of each target is extracted to determine its influence on the evaluation. Next, considering the ability of the sensor to understand a dynamic working environment, the dynamic reliability is evaluated by measuring the degree of consensus among a group of sensors. Finally, the authors discuss why and how to combine these two kinds of reliabilities. A significant improvement using the authors' method is observed in numerical simulations as compared with the recently proposed method.     

Efficient wavelet construction with Catmull–Clark subdivision

This paper presents an efficient biorthogonal wavelet construction with the generalized Catmull–Clark subdivision based on the lifting scheme. The subdivision wavelet construction scheme is applicable to all variants of Catmull–Clark subdivision, so it is more universal than the previous wavelet construction for the generalized bicubic B-spline subdivision. Because the analysis and synthesis algorithms of the wavelets are composed of a series of local and in-place lifting operations, they can be performed in linear time. The experiments have demonstrated the stability of the proposed wavelet analysis based on the ordinary Catmull–Clark subdivision. Moreover, the resulting Catmull–Clark subdivision wavelets have better fitting quality than the generalized bicubic B-spline subdivision wavelets at a similar computation cost.