波浪运动补偿稳定平台系统液压机构的仿真试验

利用Simulink仿真软件对该系统的液压补偿机构进行了仿真试验研究,并采用了PID控制、模糊控制和Fuzzy-PI复合控制三种控制算法进行比较。仿真结果表明,Fuzzy-PI复合控制的控制效果均优于常规的PID控制和模糊控制,是一种有效的控制算法;但系统还存在着一定的滞后,还需要改进。     

A Hemodynamic Study of the Effect of Neuromuscular Electrical Stimulation on Enhancing Popliteal Venous Flow

Neuromuscular electrical stimulation has been studied to be a method of prophylaxis for deep venous thrombosis by activating the calf muscle pump. However, there is little evidence of the effects of different stimulating parameters on hemodynamics and comfort levels. The objective of this paper is to compare the effects of different stimulating parameters(current amplitude, pulse-width) on hemodynamic alterations of the popliteal vein and the comfort levels in a group of fourteen healthy subjects. Doppler ultrasound detection of peak venous velocity and blood volume were taken from baseline, twelve sequential electrical stimulations and foot dorsiflexion for each subject. A visual analogue scale was used to assess the subjects' pain perception of neuromuscular electrical stimulation. The results showed that peak venous velocity and blood volume augmented as current amplitude and pulse-width increased while pain level also increased. A compromise was reached that parameters consisting of an amplitude of 10 m A and a pulse-width of 500 μs would obtain a high-peak venous velocity and blood flow volume with a relatively comfortable perception. In addition, parameters consisting of an amplitude of 20 m A and a pulse-width of 300 μs were also shown to be a promising choice. However, further studies need to be done to validate and enrich these findings.     

内应力对结构模态影响理论及数值验证

采用有限元法,从具有内应力的单元物理方程出发,推导出内应力对刚度产生影响,进而建立了内应力对结构模态影响程度的表达式。以二节点杆件为例,通过对比有无内应力情况下刚度矩阵,证实内应力不仅影响结构刚度,进而使结构振动固有频率发生偏离。而且,还会滋生出新的振动模态,验证了内应力影响模态理论的准确性;以焊缝的残余应力作为内应力实例,船体舱段为结构实例,比较不同焊接残余应力水平下结构二阶垂向振动的频率,数值验证了内应力对结构模态的影响。     

缸内直喷CNG发动机燃烧过程及NO生成率的仿真分析

基于缸内直喷CNG试验样机,在前期燃烧过程可视化试验研究结果的基础上,利用三维仿真软件FIRE建立了燃烧过程的仿真计算模型。在验证模型的基础上,计算分析了不同喷气量对缸内速度场、浓度场、火焰传播速度、温度场和NO生成率的影响。结果表明,当缸内温度大于2 000 K且喷气量当量比为0.8～1范围内时先生成NO,且最大NO生成率出现在放热率峰值之后;当喷气量减小时,放热率峰值降低,NO生成率降低。     

对转集成电机推进器研究

集成电机推进器是一种新型的推进装置,它由电机直接带动螺旋桨旋转,具有诸多优点。本文简述集成电机推进器的发展历程和结构设计特点。介绍对转电机的设计思路和方法。为满足超小型水下机器人的实际需要,设计了1个对转集成电机推进器,基于磁路方法设计了驱动用直流永磁无刷电机,然后在Ansoft软件中建立直流无刷电机的模型进行仿真分析。结果表明设计是合理的,满足设计要求,证明集成电机推进器的可行性。     

倾斜船台光学基准平面计算法及误差分析

本文介绍倾斜船台非水平光学基准平面（平行或垂直于船台表面的光学基准平面）的测量技术，可较精确地对分段及船体的几何量进行检测。对本技术的测量误差作了深入分析，工程应用和理论计算表明，其误差满足工程精度的要求。     

车辆导航数据串行多任务采集系统

PC机的数据采集一般是采用一对一的方式,单串口的PC机只能采集一个传感器的数据,如何设计PC机的分布式多任务采集系统,作者根据自己在设计车辆导航系统时的经验,介绍如何使用DELPHI平台实现PC机串口分时采集磁阻传感器HMR3300和GPS接收机的数据,并给出了完整的解决方案.