用于电容传感器的脉宽调制电路

设计了一种脉宽调制电路,用于小位移测量。电路以自制的差动电容传感器为基础,由7555定时器、滤波器等电路组成,将微小的位移变化量转化为直流电压,且与位移量基本成线性关系,能实现精度为±0.1 mm的位移测量。电路结构简单、调试方便、成本低,具有很好的稳定性和抗干扰性。实践表明:位移测量的最小二乘线性度为0.33%,灵敏度为0.065 V/mm.     

磁轴承用新型自感位移传感器设计与实验研究

随着磁轴承在航空航天、军事及民用工业领域的广泛应用,提高其位移传感器的可靠性成为发展重点。而传统磁轴承用电感式位移传感器的结构复杂、测量电路元器件过多,降低了磁轴承系统的可靠性。针对高转速和小转子磁轴承,设计了一种新型自感式位移传感器,分析了自感式位移传感器的工作原理,提出了优化的传感器结构,设计了对应的测量电路,并对传感器的性能进行了分析与测试。实验结果表明,在-0.5~0.5 mm测量范围内,传感器的线性度为±1.25%,灵敏度为25.94 mV·μm,迟滞为±0.28%,重复性为±0.22%,传感器的动态响应带宽为4.7 kHz,悬浮精度为2.4μm。该传感器完全适用于磁轴承系统,同时传感器结构简单易实现,测量电路得到大大简化,满足航空航天、军事及民用工业领域高可靠性的要求。     

闭环反馈式宽带磁通门设计

针对数字磁通门响应速度慢的缺点,在深入研究模拟磁通门的基础上,通过采用模拟电路和提高磁通门激励信号频率等方法提高了磁通门带宽。同时,采用硬件及软件补偿方法避免了模拟电路温度性能差的影响,研制了一款宽带磁通门传感器。详细介绍了该磁通门系统的硬件结构、软件设计和实验结果。测试结果显示:在±6.7×104nT测量范围内的非线性误差为0.02%,分辨率小于2 nT,信号处理电路带宽为620 Hz,数字信号输出带宽为330 Hz,在-20~80℃范围内,被测量磁场相对误差不超过±0.32%。     

简单廉价的电流基准电路

设计袖珍式廉价电子测量仪表往往需要简单而精确的基准电路.这种基准电路必须功耗小.工作温度范围宽,在电池放电到很低电压时也能工作.这里介绍一个能满足这些要求的电路,该电路还可用于各种其它场合作为基准电压或基准电流产生电路.电路如图1所示,它只由两个廉价的晶体管阵列,四个电阻和一个电容构成.实测表明,当温度变化范围为-30℃～ 70℃,电源电压变化范围为0.9～10V的情况下,输出电流变化小±3%(标准值0.1042mA).该电路在接近     

电容型土壤含水率传感器的优化设计

针对先前研制的电容型土壤湿度传感器测量范围小,误差大的问题,进行了优化设计,旨在拓宽测量范围,提高测量精度。在理论分析的基础上选择适当的工作频率,最终研制的传感器系统包含振荡电路、多路开关电路、高频探针、隔直检波电路、倍压整流电路以及处理器模块等,其含水率测量范围为0~60%,误差为±2%。该系统能实时测量土壤水分,分辨率高,适应性强,成本低,应用范围广。     

微波叶尖间隙传感器信号校准研究

利用微波雷达传感器测量叶尖间隙时,传感器存在信号泄露、背景回波叠加、电路元器件不平衡以及空间滤波效应等问题,根据这些问题的来源及影响机理,提出了一种具有环境适应性的传感器误差模型,通过将模型从空间域变换到频率域并优化误差提取算法,建立了一套提高传感器线性度、减小测距误差的校准方法。同时,选用小型24 GHz雷达传感器构建了模拟叶尖位移测量平台,使用该校准方法后,传感器线性度由±13.79%提高到±1.57%。拟合标准距离与测量值后,量程内最大测距误差下降到0.021 3 mm,最大标准差下降到0.019 7 mm。该方法有利于提高微波叶尖间隙测量精度。     

微波叶尖间隙传感器信号校准研究EI北大核心CSCD

利用微波雷达传感器测量叶尖间隙时,传感器存在信号泄露、背景回波叠加、电路元器件不平衡以及空间滤波效应等问题,根据这些问题的来源及影响机理,提出了一种具有环境适应性的传感器误差模型,通过将模型从空间域变换到频率域并优化误差提取算法,建立了一套提高传感器线性度、减小测距误差的校准方法。同时,选用小型24 GHz雷达传感器构建了模拟叶尖位移测量平台,使用该校准方法后,传感器线性度由±13.79%提高到±1.57%。拟合标准距离与测量值后,量程内最大测距误差下降到0.021 3 mm,最大标准差下降到0.019 7 mm。该方法有利于提高微波叶尖间隙测量精度。     

NJ-100B型扭转试验机微机控制检测系统的研制

对旧式扭转试验机进行了数字化改造,设计了扭矩和扭角的电子学硬件采集电路,达到扭矩测量±1%、扭角测量1′/周的测量精度.以微机为核心,编写了功能灵活的软件系统,大大方便了实验操作.改造兼顾了性能指标、功能指标及成本花费,具有较好的推广价值.     

基于VCSEL半导体激光器的浊度传感器设计北大核心CSCD

为更准确测量水体的水质浊度,设计一种基于半导体激光器的浊度传感器,该传感器由光学采集模块、信号处理模块、信号输出模块和电源供电模块组成。光学采集模块采用850 nm的VESEL半导体激光器为光源,采用后向散射光检测法,该方式具有宽线性范围,适用于悬浮颗粒物浊度测量。信号处理模块采用I/V转换电路、滤波检波电路、三级运放电路、振荡电路、温度补偿电路和差分放大器对采集的散射光信号进行处理。信号输出模块采用放大电路和4~20 mA转换电路将散射光信号转换成4~20 mA信号。传感器性能测试结果表明:浊度传感器准确度误差在±1.36%以内,稳定性优于0.6%,具有较高的准确性和可靠性。     

基于科氏粉料秤的流量测控系统设计

设计了一种对固体粉料流量进行测量控制的流量计系统.以ARM为控制核心,给出了测控系统的结构组成,设计了仪表箱硬件电路,并搭建了试验的模拟工况环境,在0.5～30 t/h的流量下,对固体粉料的流量进行了连续测量,测量精度优于±0.5%.试验结果证明了该设计的可行性和有效性.     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.