基于SVPWM五相三电平H桥逆变器中点电位控制研究

针对多相三电平H桥逆变器的电压矢量数量多,难以应用传统的空间矢量PWM算法的问题,提出了一种简化的五相三电平H桥逆变器空间矢量PWM算法。该方法采用相移SPWM思想,将五相三电平H桥逆变器作为两个由单桥臂组成的五相分别予以控制。分析选择合理的工作电压矢量及开关作用顺序,计算了开关周期内的各工作电压矢量的作用时间;不同开关状态下,针对中点电位分析的基础上,提出利用冗余矢量对中点电位进行控制,实现了电容电压的平衡。     

城市快速路互通立交选型思路探讨——以长春市快速路系统互通立交为例

互通立交在城市快速路交通系统中起着举足轻重的作用,城市快速路互通立交的选型对整个立交的交通功能、投资、占地、景观及社会和经济效益等起较为重要的作用。我国各个大中城市相继修建快速路,通过对长春快速路上的互通立交选型进行总结分析,提出一些互通立交选型思路,可供相关专业人员参考。     

航母航空弹药组成及需求分析

为了保证持续的打击能力,舰载机必须往返于航母和战场上空,通过飞行甲板上的挂弹作业完成弹药补给,因而挂弹架次以及弹药需求量对于航空作业的规划安排具有重要意义。针对美国现役"尼米兹"级航母及其舰载机F/A-1 8E/F"超级大黄蜂",重点分析了航母航空弹药类型及舰载机挂弹配置;讨论了作战架次的基本组成并总结了挂弹架次计算的基本步骤。以"尼米兹"级和"福特"级航母为例,详细计算了挂弹架次以及航空弹药需求量,并对弹药库自持力进行分析。结果表明,舰载机挂弹架次和航空弹药需求之间存在互相制约的关系。弹药需求量的分析对于航母设计和作战使用具有一定参考价值。     

缓和曲线过渡区段的地铁限界加宽

以城市轨道交通线路中的三次抛物线方程线形作为研究对象,利用几何分析方法,针对线路缓和曲线段的过渡区段,提出一种基于线路中心线的精确加宽量计算方法;结合缓和曲线段区间,形成系统的缓和曲线段加宽方法;通过控制变量法,同已有的线性插值加宽方法进行对比,说明该计算方法在一定参数范围内的线路条件下,相比于既有方法可以有效地减少隧道土方的开挖量,提高工程效率以及降低工程成本和施工周期。     

基于MDDP系统的智能压机线开发

冲压压力机作为汽车制造行业表面件加工的设备,具有多工况,变载荷、重载荷的特点,在零件加工过程中需要持续往复运行。随着设备的负荷不断增大使用年限地不断增长,一些大型的机械故障也因为磨损、疲劳以及维护保养不及时彻底等因素而开始出现,且出现频次逐渐增高。在既有的正常点巡检和例行检修保养的前提下,一些故障和问题仍无法及时发现或提前预判,从而造成了大量的非计划停机时间、人工成本、备件成本的投入。为此,引入了智能设备的概念,开发MDDP系统,实现设备自主监控、诊断、决策和预测。     

A low-cost testbed of underwater mobile sensing network

Comprised by a swarm of acoustically linked and cooperative autonomous underwater vehicles (AUVs) with onboard sensors, an underwater mobile sensing network (UMSN) will be a complementary means to fixed observatory networks, e.g. seafloor observatory networks and moored buoy arrays. It has obvious advantages over a single large AUV in higher efficiency due to parallel observation, stronger robustness to vehicle failures and lower cost. Although an UMSN can be viewed as a counterpart of wireless mobile sensing networks for air and terrestrial applications, it is much more challenging due to poor performance of underwater acoustic communication, poor performance of underwater positioning and high degree of uncertainty in vehicle dynamics and underwater environment. In order to verify key technologies involved in an UMSN, e.g. cooperation of multi-AUVs based on acoustic communication, a low cost testbed has been developed for experimental study. The design of both hardware and software is introduced. Also the results of a functional test for verification of the effectiveness of the testbed are presented.     

合理确定公路工程建设项目竣工决算

结合近年来在公路工程建设项目竣工决算审查中的实际工作经验,对公路项目竣工决算的审查工作要点和注意事项进行阐述.     

Enhancing grey prediction fuzzy controller for active suspension systems

A grey prediction fuzzy controller (GPFC) was proposed to control an active suspension system and evaluate its control performance. The GPFC employed the grey prediction algorithm to predict the position output error of the sprung mass and the error change as input variables of the traditional fuzzy controller (TFC) in controlling the suspension system to suppress the vibration and the acceleration amplitudes of the sprung mass for improving the ride comfort of the TFC used; however, the TFC or GPFC was employed to control the suspension system, resulting in a large tire deflection so that the road-holding ability in the vehicle becomes worse than with the original passive control strategy. To overcome the problem, this work developed an enhancing grey prediction fuzzy controller (EGPFC) that not only had the original GPFC property but also introduced the tire dynamic effect into the controller design, also using the grey prediction algorithm to predict the next tire deflection error and the error change as input variables of another TFC, to control the suspension system for enhancing the road-holding capability of the vehicle. The EGPFC has better control performances in suppressing the vibration and the acceleration amplitudes of the sprung mass to improve the ride quality and in reducing the tire deflection to enhance the road-holding ability of the vehicle, than both TFC and GPFC, as confirmed by experimental results.     

用于汽车运动噪声源识别的随机阵列生成法

提出一种用于汽车运动噪声源识别的二维随机阵列三步生成技术,它包括阵元法布局、基线筛选和模拟评价。利用这种技术可以大幅度提高随机目标阵列的生成速度,由此得到的随机目标比十字阵列有更好的特性。通过实车试验,更进一步验证了这种方法生成的随机目标阵列的有效性。     

泡沫铝冲击吸能器应用设计

提出了采用泡沫铝冲击吸能器来进行舰船设备限位,研究了舰船隔振装置中泡沫铝冲击吸能器的定量化设计方法,给出了泡沫铝冲击吸能器参数的理论设计计算方法和设计计算流程,并将泡沫铝冲击吸能器理论量化设计方法和设计计算程序用于船舶单层隔振装置实例泡沫铝冲击吸能器的理论设计.针对单层隔振装置计算模型,采用设计计算方法确定了泡沫铝冲击吸能器的参数.