自动气象站信号模拟器通信系统的设计与实现

阐述了通信系统在自动气象站信号模拟器应用中的意义,针对信号模拟器的特点选择了适当的通信方式和通信协议,提出了硬件抗干扰措施,并介绍了以Delphi语言为基础的上位机通信模块设计。测试与实际应用结果表明,自动气象站信号模拟器和上位机之间可以可靠、稳定地实现通信。该通信系统在自动化控制系统和智能仪器仪表中具有良好的应用前景。     

内场试验多通道静态信号模拟器设计

设计了一种87通道的多类型静态信号模拟器，信号类型包括模拟噪声、振动参量的大信号和模拟温度参量的热点偶小信号以及模拟应变参量的电阻性信号。设计中采用增加驱动能力、同类信号分奇偶通道并联输出的方式，解决了通道多、电路复杂的问题，满足了实验设备的内场测试要求，本设计可以为其他多信道信号模拟器研制提供参考。     

无线电罗盘信号模拟器抗干扰电路设计

无线电罗盘信号模拟器用于模拟产生无线电罗盘天线系统输出的含有电台相对方位角度信息的导航信号,是对无线电罗盘进行性能测试和故障检修的必备仪器。文章在对某型无线电罗盘信号模拟器电路中所受干扰进行分析的基础上,给出了抗干扰电路的设计方案,有效解决了无线电罗盘信号模拟器的干扰问题。     

回波模拟器的研制及对卫星雷达高度计发射前的性能评估

给出了回波模拟器的原理及其对卫星高度计的测试和定标方法.通过采用chirp重建技术、全去斜坡技术、海洋回波波谱数字合成技术和高速DSP技术,研制了一台用于卫星高度计测试和定标的全信号海洋回波模拟器,实现了海洋回波信号的全程路径延时模拟和全海况模拟.延时模拟精度为0.2ns、海洋有效波高模拟精度为0.5m、后向散射系数模拟精度为1dB;并将该模拟器用于了卫星高度计全系统的测试和定标.实验结果:有效验证了回波模拟器的原理及其对卫星高度计的测试和定标方法是可行的,也有效验证了一种卫星高度计的动态工作性能.     

雷达目标模拟器LFM信号线性度校准研究

线性调频(LFM)信号由于其良好的时-频聚集性,被广泛应用于雷达系统中,其频率随时间变化的线性程度,对雷达测距精度及距离分辨率影响很大.为准确模拟雷达LFM回波信号,对雷达目标模拟器所产生的LFM信号,必须进行线性度校准.本文提出了一种基于小波变换的雷达目标模拟器LFM信号线性度校准算法,通过对来自不同模拟器的大量实测数据的实验测试,证明了算法的有效性,校准精度优于0.1％.     

六自由度舰船运动模拟器随机海浪谱模拟

为了测试随机海浪引起的振动对舰载设备性能和可靠性的影响,提出利用六自由度舰船运动模拟器复现随机海浪谱,对舰载设备进行环境模拟试验。针对六自由度舰船运动模拟器的实际情况,提出双闭环控制方法,利用实时正解代替输出传感器。研究了基于谱均衡和时域随机化的随机海浪谱驱动信号生成技术,并在六自由度舰船运动模拟器上进行试验。试验结果表明,该方法能在六自由度舰船运动模拟器上模拟随机海浪谱,频域复现精度达到±1 dB。     

雷达回波模拟器设计与应用

雷达回波模拟器在雷达系统的性能测试中有着广泛的应用.以军用工控机为平台,配以自行研制的PC虚拟仪器卡,构成的雷达回波模拟器,能够完成对多种雷达主要性能指标的测试.本文给出了回波模拟的基本原理,模拟器的硬件组成以及在雷达动目标显示系统改善因子测试中的应用.     

新型结构负载模拟器研究

本文针对飞行器负载模拟器在加载过程中的出现强位置干扰影响加载精度，甚至使加载系统不能运动的特殊问题，设计了一种同步马达位置补偿校正的负载模拟器，这种结构的负载模拟器把舵机位置干扰转化了为一外力扰动，有效地控制了舵机位置干扰的不良影响。位置补偿校正驼达的输入采 用舵机的输入信号，从而使负载模拟器对不同刚度的舵机加载时都能运动起来，为采用先进的控制方法提供了有利条件。使负载模拟器具有较强的适应性。     

基于振幅比例变换法的程控型无线电罗盘信号模拟器设计

无线电罗盘信号模拟器用于模拟产生无线电罗盘天线系统输出的含有电台相对方位角度信息的导航信号,是对无线电罗盘进行性能测试和故障检修的必备仪器。文章在简要分析无线电罗盘"分离式"天线系统的结构组成和信号特性的基础上,重点分析了基于"振幅比例变换法"的无线电罗盘信号模拟器的设计思路和工作原理,给出了"单片机+电感线圈+方位控制电路"的电路结构模型。基于"振幅比例变换法"的无线电罗盘信号模拟器采用全固态结构,具备程控应用功能,模拟方位角度输出快速、准确,电路实现简单,体积小、质量轻。     

基于Bouc-Wen模型的阻尼负载模拟器研制

研制了一种数字控制阻尼负载模拟器,可以模拟Bouc-Wen等非线性滞回模型,通过设定参数来模拟不同的负载特性.如果应用在地震模拟振动台实验中,通过改变负载模拟器参数就可以模拟成不同类型的阻尼器,一方面可以研究阻尼器对结构的减振效果,另一方面可以研究不同类型结构所需要的最优阻尼器参数.该阻尼负载模拟器可以广泛应用于实验领域来代替阻尼器,是一种主动调节型的阻尼器.     

A new type haptics-based virtual environment system for assembly training of complex products

Virtual reality (VR)-based assembly training has been an interesting topic for the last decades. Generally, there are two shortcomings for nowadays virtual assembly training systems. One is that the operators cannot move around the virtual environment in a natural way as people activity in the real world: they are constrained in a fixed position or can only move in a limited space. The other is that most of the virtual assembly training systems are based on geometry constraint modeling only, which lacks haptics feedback. A new type haptics-based virtual environment system for assembly training of complex products is described in this paper. A new low-cost motion simulator is designed and integrated with the virtual environment to realize free walking by human. An automatic data integration interface is developed to transfer geometry, topology, assembly, and physics information from a computer-aided design system to a VR application, and a hierarchical constraint-based data model is rebuilt to construct the virtual assembly environment. Physics-based modeling and haptics feedback are undertaken to simulate the realistic assembly operations. The application examples and evaluation experiments demonstrate that both motion simulator and haptics have great value for training of assembly processes.     

船用中速机油使用性能的评定方法

通过对船用中速机油的现有台架进行改造,增加润滑油净化系统,建立了船用中速机油使用性能评定方法。该方法可模拟船舶发动机实际使用情况,考察船用中速机油受水污染后的碱值衰变、分水性能、活塞清净性及抗磨损等实际使用性能。通过对几种船用中速机油的评定试验表明,选择的试验条件合理,该评定方法可以满足评价油品综合性能的要求。     

船舶分油机操作训练模拟系统的研制

针对船舶分油机的工作特点,在简要介绍其组成及功能的基础上,采用PLC控制开发了船舶分油机模拟仿真系统,该模拟实验系统能够模拟船舶分油机系统的工作原理和操作、控制过程,并可设置船舶分油机常见的故障。通过该模拟器进行实验可以熟悉各种故障现象,熟练掌握船用燃油分油机的操作程序、操作要领和保养维护方法。     

双阀并联控制在船舶舵机电液负载模拟器多余力抑制中的研究

由于船舶舵机电液负载模拟器所模拟的水动力载荷很大,要求加载系统不仅要有很大的出力而且具有很大的负载流量。为满足系统大流量的要求而又能有效抑制被动加载时的多余力,提出了由高响应大流量三级电液流量伺服阀和p-qv伺服阀组成的双阀并联控制方案。通过对船舶舵机电液负载模拟器的建模,p-qv伺服阀模型的分析简化,设计了双阀并联控制实时控制系统。对比双阀并联控制和单流量伺服阀控制的试验曲线,可以看出被动加载时双阀并联控制比单流量伺服阀控制可以更有效地抑制舵机系统启停和换向时的多余力,明显改善系统动态加载性能。     

Improved anti-shudder performance of ATFs—Influence of a new friction modifier and surface chemistry

Among OEM strategies for increasing fuel economy and reducing emissions, driveline performance optimisation by using automatic transmissions is particularly important. Technology advances in automatic transmission designs are leading to continued growth of the number of vehicles with automatic transmissions. In fact, over the next five years, it is expected that the market share for automatic transmissions will increase to greater than 60%, with Europe being the largest region for this growth.The performance of automatic transmissions, especially anti-shudder performance, is highly dependent on friction modifiers and other additives in automatic transmission fluids (ATFs). These additives, in a manner similar to engine oil additives, are expected to interact with the steel and clutch material surfaces to form surface films that provide the desired performance. Hence, understanding the tribochemical processes in this automatic transmission system is a very important step towards performance optimisation. While the tribochemistry of engine oil additives and the nature of tribofilms on metallic surfaces are relatively well researched, the tribochemistry of ATFs still remains largely unclear. One reason for this is the level of complexity in analysing the friction materials of automatic transmission systems. Separating lubricant-derived species from the composite clutch friction materials is not trivial.This paper presents a comprehensive look at the tribochemistry of a new friction modifier in ATF systems and assesses the nature of the tribofilms formed on steel and composite friction materials in a variable speed friction test (VSFT) apparatus, which was used to simulate the clutch friction process. The tribofilm evolution is correlated with the tribological response as ageing occurs. Functional groups from the friction modifiers were found on the friction couple surfaces after the test and the mode of their action is discussed. These groups were proposed to form a layer of tribofilm on the top surface after rubbing. The correlation between observed tribochemistry processes and the tribological performance are discussed in detail.     

汽车发动机舱热管理的CFD技术应用

CFD数值仿真技术已经广泛应用于汽车设计中。论文以某MPV车型发动机舱过热为例,通过Hy-permesh和Fluent软件,建立了发动机舱气体流动的仿真模型并进行了分析计算,很好的实施了汽车发动机舱的热管理,有效的解决了发动机水温过热的问题。     

新型数字液压2自由度摇摆台建模与试验研究

摇摆台广泛用于模拟舰船、车辆的运动姿态,在车船设备测试、驾驶模拟器等国防与民用领域都有重要的应用价值。基于此,针对自行研制的模拟海洋环境的2自由度液压运动平台,介绍增量式步进电动机、四边滑阀、非对称液压缸、摇摆台架、同步反馈机构等构成的近似开环控制的系统结构和工作原理,建立其运动学和动力学方程,并通过状态方程描述阀控非对称液压缸换向时的跳变特性。在Matlab/Simulink中构建系统的非线性控制模型框图,将仿真与试验结果进行对比分析,表明了该数字液压摇摆台的可行性。     

A fuzzy logic urea dosage controller design for two-cell selective catalytic reduction systems

Diesel engines have dominated in the heavy-duty vehicular and marine power source. However, the induced air pollution is a big problem. As people's awareness of environmental protection increasing, the emission regulations of diesel-engine are becoming more stringent. In order to achieve the emission regulations, the after-treatment system is a necessary choice. Specifically, the selective catalytic reduction (SCR) system has been widely applied to reduce the NO_X emissions of diesel engine. Different from single-cell SCR systems, the two-cell systems have various benefits from the modeling and control perspective. In this paper, the urea dosage controller design for two-cell SCR systems was investigated. Firstly, the two-cell SCR modeling was introduced. Based on the developed model, the design procedure for the fuzzy logic urea dosage controller was well addressed. Secondly, simulations and comparisons were employed via an experimental verification of the whole vehicle simulator. And the results showed that the designed controller simultaneously achieved high NO_X reduction rate and low tail-pipe ammonia slip.     

Unlubricated gross slip fretting wear of metallic plasma-sprayed coatings for Ti6Al4V surfaces

Plasma-sprayed Al–bronze or CuNiIn coatings are often applied to protect against fretting wear and extend the operational life of Ti-alloy compressor blades in turbine engines. In order to develop a fundamental understanding of how these coating systems perform under gross slip fretting conditions, bench level fretting wear tests were conducted at room temperature to simulate cold engine startup. Alternative coatings such as plasma-sprayed molybdenum and nickel were also evaluated because of their potential for reducing fretting wear under certain simulated engine conditions. The combination of scanning electron microscopy (SEM), surface profilometry, surface chemistry (EDS), and friction analysis were used to study coating performance and evaluate the interfacial wear mechanisms. In this study, it was determined that all coatings caused significant damage to the mating Ti6Al4V surfaces and that the wear mechanisms were all similar to those of the uncoated baseline case.