基于补偿零序压差原理的110kV线路纵向故障保护方案

针对现有保护装置没有计及纵向故障的保护方案的问题,首先分析110 kV负荷站变压器中性点接地和不接地方式下线路的单相、两相断线故障特征。其次依据断线故障特征提出了基于线路双端零序电气量的补偿零序电压差动原理的断线保护方案,实现了断线故障的快速可靠动作。最后在110 kV纵联差动保护装置上增加断线保护逻辑,并在数字仿真系统上建立110 kV负荷站输电系统,验证了所提断线保护方案的有效性。     

TPT—2PTT并联机床奇异性及平稳性研究

提出了一种新型的TPT—2PTT三平移自由度并联机床构型。在运动学正、逆解的基础上，对雅可比矩阵及速度进行了研究，分析了机构的奇异性及平稳性。研究结果表明：该机构具有运动平稳、不存在奇异点、易于控制等优点。     

An efficient multi-objective optimization method for black-box functions using sequential approximate technique

Multi-objective optimization problems in practical engineering usually involve expensive black-box functions. How to reduce the number of function evaluations at a good approximation of Pareto frontier has been a crucial issue. To this aim, an efficient multi-objective optimization method based on a sequential approximate technique is suggested in this paper. In each iteration, according to the prediction of radial basis function with a micro multi-objective genetic algorithm, an extended trust region updating strategy is adopted to adjust the design region, a sample inheriting strategy is presented to reduce the number of new function evaluations, and then a local-densifying strategy is proposed to improve the accuracy of approximations in concerned regions. At the end of each iteration, the obtained actual Pareto optimal points are stored in an external archive and are updated as the iteration process. The effect of the present method is demonstrated by eight test functions. Finally, it is employed to perform the structure optimization of a vehicle door.     

Anthocyanins composition and antioxidant activity of two major wild Nitraria tangutorun Bobr. variations from Qinghai-Tibet Plateau

Nitraria tangutorun Bobr., a unique kind of fruit, widely spreads in the Qinghai-Tibet Plateau. In the present study, nine anthocyanins were identified in two variations (purple fruit and red fruit) of N. tangutorun by HPLC/DAD-ESI/MS. Cyanidin-3-O-(trans-p-coumaroyl)-diglucoside (215.76 ± 22.91 mg of Mv3G5G equivalent per 100 g of fresh weight) and pelargonidin-3-O-(p-coumaroyl)-diglucoside (5.13 ± 0.35 mg of Mv3G5G equivalent per 100 g of fresh weight) were the main anthocyanins in the purple and red fruits respectively. In addition, most of the anthocyanins were acylated by coumaric acid, and the rare anthocyanins that naturally presented a coumaric acid in both cis and trans configurations have been detected. Furthermore, the extract of the two variations showed significantly different antioxidant activity (p < 0.01) according to DPPH, ABTS and FRAP assay. Purple fruit possessed higher antioxidant activity than red fruit. There were significant correlations between antioxidant activity and both the total polyphenol content and anthocyanins content. This work is valuable for elucidation of anthocyanins composition in N. tangutorun and for further utilization as a functional food and medicine material.     

Towards low emissions and high thermal efficiency of gasoline compression ignition engine under high loads by modulating the fuel reactivity and injection strategy

Gasoline compression ignition(GCI) is a practicable way to obtain low emissions and high thermal efficiency of gasoline-like fuels in internal combustion engines. In this paper, the research octane number(RON) and injection strategy were coordinated to optimize the GCI engine performance and emissions under high loads. The direct injection and port injection were used to achieve two injection strategies: direct injection(DI) and port injection plus direct injection(PIDI), and the primary reference fuels(PRF) with the RON of 60, 70, 80 and 90 were used. The results show that using lower RON fuels under high loads, DI mode can achieve higher efficiency, while PIDI mode can achieve lower combustion noise at an expense of slightly lower fuel economy. When the DI mode is converted to PIDI mode with a pre-injection ratio of 30%, using PRF70 under 12 bar and the exhaust gas recirculation(EGR) rate of 40%, the gross indicated thermal efficiency and the maximum pressure rise rate are reduced by 1% and by 2 bar/°CA, respectively, while the particle emissions also decrease significantly, thus achieving low emissions and high efficiency. However, under the same load and EGR rate, DI mode produces less regulated and unregulated emissions than PIDI mode. In addition, the effect of fuel RON was obvious, the lower RON fuels exhibit obvious three-stage heat release in PIDI mode, however, PRF90 with higher RON only exhibits two-stage heat release, and the peak value of the firststage heat release rate is also lower than those of other fuels.     

颗粒计数仪在北京第九水厂水处理中的应用

介绍了颗粒计数仪在水厂的使用效果,并论述采用该计数仪对于控制水质安全和优化工艺过程的必要性．对水厂的工艺过程改进有一定的参考价值。特别是对水质的优化监测．降低饮用水中致病原虫的风险将起非常重要的作用。     

硅基PIN光电探测器结构参数对其性能的影响

对硅基PIN光电探测器器件模型进行了理论分析,讨论了硅基PIN光电探测器的I-V特性与器件的i层厚度和整体宽度的变化关系,并进行了仿真分析。实验结果表明,随着i层厚度从5μm增加到70μm,器件的正向电流逐步减小,且i层厚度与其正向电流成反比;随着器件宽度从50μm增加到90μm,器件的正向电流逐步增大,且器件宽度与其正向电流成正比;引入保护环结构可以明显降低器件的暗电流。对PIN器件的结构参数进行了优化设计,结果表明在所设置的器件工艺条件下,当器件的i层厚度为50μm、整体宽度为70μm时,器件的性能最佳。