双缘COT调制数字电压型控制Buck变换器分析

为了提高恒定导通时间(constant on-time, COT)调制开关变换器的输出电压稳压精度,基于COT调制和双缘脉冲宽度调制的特点,提出了一种工作于电感电流连续导电模式(continuous conduction mode, CCM)的开关变换器双缘恒定导通时间(dual-edge constant on-time, DCOT)调制方法.介绍了DCOT调制数字电压型控制Buck变换器的工作原理,对比分析了COT调制和DCOT调制数字电压型控制Buck变换器的稳态性能和瞬态性能.结果表明:相比于COT调制,采用DCOT调制的数字电压型控制Buck变换器提高了输出电压的稳压精度,其大小为输出电压纹波峰峰值的50%,且瞬态调节时间减少了1个开关周期.最后,通过仿真和实验结果证明了理论分析的正确性.      

物流信息资源整合模式探讨

针对物流系统的信息资源,提出通过企业信息平台和公共信息平台的构建这两大模式来实现物流信息资源的有效整合,而在这两大模式的运作中,双方有效的衔接及信息的共享是决定运作是否成功的关键所在。     

自锚式悬索桥的调索设计

该文根据佛山平胜大桥的调索设计,论述了自锚式悬索桥调索的控制因素与目标,并通过各种可能的调索方案进行对比,选取了最优的吊索张拉方案.最后结合全桥模型试验,验证了调索设计的正确性、合理性.     

一种新型排水结构的排水性能试验研究

目前边坡和支挡工程中最常用的排水结构(PVC排水管)服役一定年限后,易发生堵塞,排水功能失效。为研究一种排水效率高、不易堵塞的新型排水结构(排水钉),在室内开展了历时4个月的PVC排水管和排水钉的排水对比试验,系统研究两者的排水性能和抗淤堵性能;同时开展排水钉设置间距和设置长度对自身排水性能的影响试验,并分析排水钉的反滤机制。结果表明:排水钉能持续保持良好的排水性能,而PVC排水管排水性能则逐渐下降,包裹PVC排水管的土工布发生了一定程度的淤堵,使流速最大降幅达35%;砂土中排水钉的有效排水半径约为1.0 m,排水钉置入边坡应穿过最危险滑动面至少1.5 m;排水钉周围形成天然的反滤层,能发挥排水、挡土和防淤堵的作用。     

克令吊起升系统典型液压故障分析

文章以设备说明书和技术通函为理论依据,结合笔者多年的克令吊实际管理经验,以IHI H300160-300型克令吊为例,介绍了船用克令吊起升(俗称钩头)系统的典型液压故障,给出了分析处理液压问题的处理思路,总结出了非常实用的液压故障排查方法和经验。     

Comparison between North-South Aid and South-South Cooperation: Based on the analysis of the new development finance institutions

According to the different players, development cooperation is often divided into North-South Aid and South-South Cooperation, both of which have a history of several decades. Since the beginning of the 21st century, the rise of a number of emerging economies has brought South-South Cooperation into a new stage, which can be seen from the establishment of some new development finance institutions led by developing countries. BRICS Bank, Asia Infrastructure Investment Bank (AIIB) and Silk Road Fund are three important new development finance institutions. Compared with the traditional development finance institutions like World Bank and International Monetary Fund (IMF), they have their own concepts of development cooperation, which are different from the traditional ones. First, the new finance institutions pay more attention to the equality between partners, not imposing conditions and respecting the ownership of development partners. Second, the new development finance institutions value the market philosophy, which means that they emphasize the importance of field investigation and implement development cooperation in accordance with the actual needs of the partners and the comparative advantages of the providers. Finally, the new development finance institutions focus their resources on problem-solving and avoid doctrines-imposing. They believe that it is easier for the developing countries to achieve development through a gradual and bottom-up model. Although there are differences between the traditional and new development finance institutions, the latter is not parallel to or substitute of the former. They can cooperate with each other and provide better public goods for international cooperation through inclusive competition.     

Efficient Dynamic Threshold Group Signature Scheme Based on Elliptic Curve Cryptosystem

The short secret key characteristic of elliptic curve cryptosystem （ECC） are integrated with the （ t, n ） threshold method to create a practical threshold group signature scheme characterized by simultaneous signing. The scheme not only meets the requirements of anonymity and traceability of group signature but also can withstand Tseng and Wang＇s conspiracy attack. It allows the group manager to add new members and delete old members according to actual application, while the system parameters have a little change. Cryptanalysis result shows that the scheme is efficient and secure.     

基于北斗导航系统的车载嵌入式终端的开发与实现

介绍了基于北斗卫星导航系统开发车载终端的特点及硬件性能和外部结构,并针对公路军事运输的特点进行了功能设计。在开发过程中,将嵌入式技术、计算机技术、GIS技术、北斗卫星定位通讯技术有机结合起来,实现了对移动目标的图上定位和远程通信指挥。     

城市轨道交通建设工程声像档案归档业务探索

从服务于工程建设档案、适应新时代工程档案管理需要出发,成都市城市建设与自然资源档案馆组织相关专业力量,编写了成都市城市轨道交通建设工程全部子项的声像档案制作与归档要求。本文重点介绍了城市轨道交通建设工程声像档案归档类别及范围,供探讨思考,以促进建设工程声像档案接收范围的拓展和服务的提升。