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161.
电容电压的平衡是模块化多电平换流器正常运行的前提,是所有控制算法必须考虑的基本问题。介绍模块化多电平换流器的基本运行原理,研究了载波移相在模块化多电平中的应用。为抑制电容电压的不平衡,设计了电容电压均衡控制器,最后在MATLAB/Simulink中搭建了仿真模型,仿真结果表明设计的控制器能较好地稳定电容电压。 相似文献
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Research has shown that even when rail travel is the most cost-effective mode of transport for a particular journey, many travellers will still choose other modes. This indicates the existence of non-financial barriers to rail use, and this paper reviews the evidence on the importance of such barriers, focusing particularly on the UK but also considering research from other countries. A total of 37 distinct barriers were identified, and these can be divided into “hard”, “soft” and “complementary” factors. Travellers are unlikely to consider these barriers individually, viewing them instead as a package, which can make it difficult to identify which barriers are most significant. In many cases, all barriers which exist for a particular traveller will need to be addressed before mode shift occurs. After considering the relative importance of the different barriers, the paper concludes by making some suggestions as to the most effective ways in which these barriers can be overcome and mode shift to rail achieved. This has key implications for transport policy, as it can inform the targeting of the limited funds available to influence travel behaviour and increase the sustainability of travel patterns. 相似文献
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The feasibility of implementing short sea shipping (SSS) between two specific ports has been typically approached on the operative level, in terms of time and cost for a specific origin–destination pair. This paper focuses on the strategic level. Particularly, its goal is to study the potential of SSS in different industrial sectors by analysing their freight-distribution strategies. To achieve the objective, some standard freight-distribution strategies are defined based on the requirements of the industry, the demand and the product being transported. The information is complemented with a survey of more than 100 Spanish companies distributing internationally. As a result it is concluded that there are economies of scale related to the size of the carrier (the ship) and its capacity to absorb the variability in demand. This potential increases with the cargo value. Additionally, a framework of supply/distribution chains is provided which can help to identify potential customers/sectors and the feasibility of new potential shipping lines. The value of this paper resides in its approach (strategic, instead of operational/tactical), and the solid groundwork point provided for future researchers. 相似文献
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秦沈客运专线PC箱形简支梁现浇施工技术 总被引:1,自引:1,他引:0
通过对秦沈客运专线B2 8-9标段施工实践的总结 ,综合介绍PC简支箱梁的现浇施工方法 ,并对现浇膺架的设计及膺架预拱度调整、混凝土施工、预施应力、高位落梁及纵、横向移梁等施工工艺作详细的论述。 相似文献
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从主电路的选择出发,提出采用输入串联,输出并联的2个半桥电路双模块DC-DC变流器来实现主从控制方式,描述了DC-DC控制系统框图,并对控制部分如何用微机产生2个半桥的驱动波形,如何解决均压及移相问题进行了具体阐述,试验表明系统具有较好的动态性能,输出纹波小。 相似文献
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介绍了一种以微处理器技术为核心,实现铁路信号移频发送设备智能化的方案,用来替代由分离元件构成的移频发送设备的接口电路,从方案设计思想、设备的硬件组成框图和软件设计流程等方面进行了详细的论述。该方案采用了以ATMEI公司的ATmaga128芯片为核心的微处理器技术,由于晶振的高稳定性和单片机的高可靠性及智能化,提高了原有设备的性能。 相似文献