200 W光伏发电单模块DC/DC变换器设计

随着能源问题和环境问题的日益严重,开发并利用清洁可再生能源是重点问题。本研究根据DC-DC功率变换器课程设计要求,选择Boost级联为主电路,在此基础上对主电路进行了拓扑优化,并完成了相关元器件参数的设定和型号选型,最后对主电路进行了仿真实验计算,得出本设计功率损耗约为15 W,工作效率92.5%。计算结果表明本设计能满足设计要求,系统各元器件工作在较为理想的状态。     

蒲石河抽水蓄能电站输水系统充排水试验方法

高水头大型抽水蓄能电站输水系统的充水和排水,是电站投入运行不可缺少的一项安全检验,初期充排水试验是加载、卸载、检查、监测、发现问题和处理缺陷的过程,为今后电站正式运行提供安全可靠的质量保证。本文详细介绍了辽宁蒲石河抽水蓄能电站输水系统充排水试验方法,可供类似工程参考。     

基于HOG和SVM的双眼虹膜图像的人眼定位算法

针对近红外光下现有的人眼定位算法普遍存在准确性不高、泛化能力不佳等问题，提出了一种基于方向梯度直方图（HOG）和支持向量机（SVM）相结合的双眼虹膜图像的人眼定位算法。利用HOG提取虹膜图像的人眼特征，并结合SVM分类器对HOG特征进行训练从而实现人眼的精确定位。为了减少漏检和误检，进一步提高定位准确率，又提出了多级级联SVM分类器算法；另外针对近红外光线下虹膜图像独特的灰度分布特点，设计了一种图像预处理方法，能够显著提高人眼定位速度。在MIR2016和CASIA-IRIS-Distance数据集上的实验结果表明，基于HOG和SVM的双眼虹膜图像的人眼定位算法具有高准确率、强泛化能力和高实时性。     

A reconfiguration of fire station and fleet locations for the Santiago Fire Department

The geographical distribution of the population of the city of Santiago, Chile, has changed significantly in recent years. In spite of this fact, the location of the fire stations has remained unchanged. We propose a model for the optimal location of the fire stations and a fleet assignment for the Santiago Fire Department (SFD), aimed at maximising the number of events attended to with a predefined standard response. The results of the model are compared with respect to the current location of fire stations and fleet assignment in the SFD. There are different types of resources (stations and vehicles), and different types of events in which the same types of vehicles are used. We analyse various possible current and future scenarios, using a forecast based on historical data. Our results show that by optimally reallocating the resources a 10–30% increase can be achieved in the number of emergency calls that are attended to with an adequate response in time and number of vehicles, without the need for additional fire stations or vehicles. Thus our contribution is empirical and relies on the real world application which is being considered by Chilean government.     

对厂用电负荷进行实际核算的尝试

用需要系数法对水电厂机组厂用电负荷进行核对计算,并与实测数值进行比对,为设备异动风险评估及各种有关电气安全性评价提供参考。     

剂量电离室数字滤波器设计

为满足上海先进质子治疗装置治疗头中剂量电离室电子学A/D转换后的数据率和降噪要求,提出一种多级级联的数字滤波器结构。本文中设计LMS自适应滤波器来滤除50 Hz的工频噪音,相比于传统数字陷波器,不会对有用信号造成损失。通过MATLAB软件仿真对信号处理结果表明,电子学延时减少到170μs,数据率50 kHz,基本符合量化后的剂量数据处理要求。     

Purging Metal Impurities from Nuclear Fuel using Centrifuge Cascades with Additional Feed Component

Abstract

Nuclear fuel can be purged, that is metal impurities can be extracted from the uranium hexafluoride, by feeding an additional component, a kind of Freon, C₆F₁₂, which is chemically stable with respect to uranium hexafluoride, into the centrifuge purge cascade. The metal impurities are then continuously withdrawn from the purge cascade as a result of the additional feed. Centrifuges can not be easily used for the purge process without the Freon because the amount of metal impurities in the nuclear fuel is usually very small, thus the flow of impurities withdrawn from the product end of the purge cascade needs to be periodically closed down to minimize the loss of uranium hexafluoride. This results in the accumulation of light impurities such as air and HF in stages near the product end of the purge cascade. These light impurities inside the centrifuges may reduce the working effectiveness of the centrifuges or even put them out of service. The additional Freon eliminates this problem, because the light gas can be extracted from the cascade as soon as it reaches the product end of the cascade. Numerical calculations using a typical metal impurity CrO₂F₂ illustrate the effect of the additional Freon feed in the purge process.     

水电站电动盘车启动电流的理论计算及问题处理

水轮发电机组轴线的测量与调整是机组总装完成后的一道关键性工序,机组轴线的测量与调整一般通过电动盘车来完成。工程中常采用经验公式来计算电动盘车时加入定转的电流值,多个电站的实践证明,运用经验公式计算出的启动电流与实际加入的电流偏差较多,而采用电磁学推导公式计算的启动电流与实际加入的电流值比较接近。详细阐述了电动盘车启动电流的计算过程和实际应用效果,同时,对电动盘车因不平衡磁拉力及剩磁现象对盘车带来的影响,进行了专项技术分析并采取了相应的解决措施。研制的对应措施在多个水电站得到了运用,经过长时间的运行,发现机组的振动、摆度均在允许的范围内且运行情况良好。研究中推导的电动盘车计算公式及相关问题的处理方式,对水电站轴线的调整有一定的参考和借鉴作用。