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大功率可编程直流电流源监控系统的开发
Development of Monitoring System on Programmable High-Power DC Current Source
 [PDF]

, 同向前, 黄金亮
Instrumentation and Equipments (IaE) , 2015, DOI: 10.12677/IaE.2015.34016
Abstract: 本文针对可编程直流电流源输出电流的幅值、频率、波形可设定的要求,设计了电流源的系统组成方案和电流参考波形的调制算法。可编程直流电流源由基于PC机的上位机监控系统和基于DSP控制的DC-DC变换器组成,两者通过RS485工业通信总线联系。基于LabVIEW的上位机监控系统的开发可实现对可编程直流电流源输出电流波形的调制和监控。实际装置的运行结果表明,上位机监控系统的设计满足装置的功能要求,操作简明,运行可靠。
According to the output current amplitude, frequency and waveform requirements of the pro-grammable DC current source, the structure scheme and the modulation algorithm were designed. The programmable DC current source is composed of PC monitoring system and DC-DC converter controlled by DSP. PC communicates with DSP by the industrial communication bus RS-485. The PC monitoring system based on LabVIEW is developed, which can achieve the modulation and monitoring on DC current source output. The operation results show that the PC monitoring system satisfies the requirements of device, with simple operation and high reliability.
农村垃圾中转站到处理厂的周期性运输方案研究
Research on the Program of Periodic Transportation from Rural Waste Transfer Station to Treatment Plant
 [PDF]

, 连淑君
Operations Research and Fuzziology (ORF) , 2014, DOI: 10.12677/ORF.2014.43005
Abstract:
本文针对农村垃圾中转站到处理厂的运输进行研究。根据实际情况,提出了两个周期性运输方案:周期运输,即先将垃圾在中转站内进行存储,然后中转站按各自周期将垃圾清运到处理厂;每日运输,有余量的周期性运输,即每天将垃圾运往处理厂,但由于车辆不满载造成垃圾剩余,周期性清运剩余垃圾。通过对运输方案建立费用最小数学模型,从而得出各垃圾中转站的最优中转周期。最后通过具体的案例,证明了方案的有效性。文章模型科学,数据分析合理,分析了农村垃圾的处理方案的优化问题,有一定的参考价值。
The transportation from rural waste transfer station to treatment plant is studied in this article. Based on actual situation, the author proposed two programs of periodic transportation. One is periodic transportation. It refers that the waste was stored in the transfer station first. Then ac-cording to their respective cycle, all the waste in the transfer station is transported to plant. The other periodicity transportation is that the waste is transported every day, but due to the vehicle is not loaded, the surplus waste must be put in the transfer station. After a period of time, the rest of the waste is transported to treatment plant. Transport through the cost minimum mathematical model is set up, which obtains the optimal transfer cycle of waste transfer station. Finally the computational result of the case proves the availability of our programs. The models are scientific and the analysis of data is reasonable in this article. It analyzes the optimization problem of rural waste management option. And it has reference values.
中国高速列车牵引传动系统比较分析
Comparison of Chinese High-Speed Train Traction Drive System
 [PDF]

郑英, 李翔
Open Journal of Transportation Technologies (OJTT) , 2014, DOI: 10.12677/OJTT.2014.33010
Abstract:

本文主要介绍中国高速列车的主要车型,并且重点从技术层面上对比分析了CRH1、CRH2、CRH3、CRH5、CRH380A和CRH380B型动车组的牵引传动系统的主回路及其控制的特点,同时就CRH2型动车组的脉冲整流器和逆变器的主体结构进行了详细的介绍和分析,分析了3电平脉冲整流器的优缺点,同时与具有典型特点的CRH5型车的载波移相多重化的控制特点进行了分析和对比。就CRH2和CRH5型车的中间直流环节和逆变器的控制策略、控制方法进行了详细的介绍和解释,对比其各方面特性的差异,从而得出结论。对于中间直流环节的二次脉动的处理方面,CRH2、CRH5和CRH380A通过逆变器的软件控制,调节逆变器频率,使逆变器输出电压在正负周期的电压与时间乘积趋于相等,来消除二次谐波电压的影响,而CRH3和CRH380B设置了二次谐波吸收回路,通过LC串联谐振电路来消除二次谐波。各车型都采用异步电机的矢量控制,以间接矢量控制为主。
The paper mainly introduces Chinese high-speed trains and analyzes the characteristics of the main circuit and the control block diagram of CRH1, CRH2, CRH3, CRH5, CRH380A and CRH380B. At the same time, the detailed description and analysis of the structure of the pulse converter and the inverter of CRH2 are introduced. The paper also compares the advantages and disadvantages of the tri-level pulse rectifier and the carrier phase shift multi-pulse. Through considering the control strategy of CRH2’s and CRH5’s DC link and the inverter control method in detail and explaining the differences in different aspects, the conclusion is drawn. CRH2, CRH5 and CRH380A adjust the inverter frequency through the inverter control software, so that the product of voltage and time of the inverter’s output voltage can be equal in the positive and negative cycle to eliminate the influence of the second harmonic voltage. While the CRH3 and CRH380B set the second harmonic absorption circuit, the LC series resonant circuit is used to eliminate the second harmonic. All these motors use the vector control. Indirect vector control is mainly used.

清乾隆年间台湾林爽文事件性质辨析

安徽大学学报(哲学社会科学版) , 2007,
Abstract: 史学界普遍认为,清乾隆年间台湾林爽文事件是一场“农民阶级反对地主阶级的阶级斗争”,也有学者认为是“恢复明室”的“革命”。但从林爽文事件爆发的原因、初期事件参与者的诉求、起事后林爽文竖旗建号许封文武官员、乾隆帝平定事件的根本出发点等四个方面考察,林爽文事件的性质是由危害台湾地方治安转化为危害台湾的“动乱”,实质上是一宗企图分裂国家的事件。
间伐强度对柏木低效人工林灌草多样性的影响

东北林业大学学报 , 2015,
Abstract:
几丁质酶研究历史和发展前景
,
微生物学通报 , 1993,
Abstract:
黄杆菌(Flavobacterium sp.)几丁质酶的纯化和性质
,
微生物学报 , 1994,
Abstract: 黄杆菌(Flavobacteium sp.)在几丁质的诱导下产生几丁质酶.通过(NH_4)_2SO_4沉淀、DEAE纤维素柱层析、Sephacryl 300柱层析及Sephadex G-75柱层析,从Flavobacterium sp.培养上清液中分离纯化了几丁质酶.SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)纯度分析表明,纯化后的几丁质酶达到了均一的程度.用SDS-PAGE测得该酶的分子量约45D00道尔顿.该酶水解几丁质的最适pH为 7.0,最适温度为50℃,-20C贮存两年以上仍有活性.水解几丁质的Km值为5.0mg/ml.金属离子对几丁质酶活性影响较大,Ca~(2+) 、Co~(2+)’和Cu~(2+)对酶有激活作用.而NH_4~-、Ba~(2+)、Mg~(2+)、Mn~(2+)对酶有抑制作用.几丁质酶水解几丁质的产物是几丁质二糖.
高糖尿病患者教育质量的临床研究
宋梅,
第三军医大学学报 , 2007,
Abstract:
综合孔径微波辐射计二阶量化数字相关器研究
,
电子学报 , 2002,
Abstract: 微波辐射计作为一种无源遥感器,在遥感技术领域有着巨大的应用前景.传统的微波辐射计的空间分辨率受到天线孔径的限制.综合孔径微波辐射计利用了干涉测量原理和复相关技术,是一种可以有效地提高空间分辨率的新型辐射计.本文针对综合孔径微波辐射计的数字相关器进行了深入研究,分析论证了二阶量化数字相关器的工作机理,并对采用该种相关器的系统的信噪比进行了分析.初步的试验验证结果证明了该方案的有效性.
圆锥扫描自动跟踪体制在船载“动中通”中的应用
鸿宇,胡正
南京邮电大学学报(自然科学版) , 2006,
Abstract: 结合实际研究项目介绍了一种新型船载卫星通信系统的关键技术,该系统采用的是捷联式的有源稳定跟踪平台,特点在于利用圆锥扫描原理实现天线姿态稳定跟踪,从而降低了系统对天线稳定平台的精度要求,主要探讨了圆锥扫描技术在天线自动跟踪系统中的应用。阐述了圆锥扫描自动跟踪的原理、系统组成以及系统的具体实现方案,分析了扫描参数对系统性能的影响及选择原则。实验测试表明,该系统能够获得较高的跟踪精度和跟踪实时性,能够使天线稳定地对准卫星。
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