A Superwideband Waveguide System for Measuring the Attenuation of Electromagnetic Waves by Fragments of Vegetation

A laboratory bench and technique for measuring the attenuation of microwaves by fragments of vegetation is described. It is shown that the created measuring system and proposed technique ensure the obtaining of continuous attenuation spectra in a wide band of frequencies. Some preliminary results from measuring attenuation by aspen branches are given for the frequency band 0.8–8.5 GHz.     

基于LabVIEW的低频信号频率测量

在对汽车底盘实验台架变速箱的输出轴进行转速测量时,通过测取霍尔传感器输出的脉冲信号的频率得到转速值,而使用LabVIEW内部子VI无法准确测量低于1Hz的信号的频率。为解决这一问题,提出了用测波峰之间时间和测时间段内波峰数两种方法测量低频信号的频率。使用仿真信号比较了两种方法测量的准确性,结果表明,用测波峰之间时间的方法得到的测量结果更为准确。用该方法对变速箱输入输出轴转速进行了测量,得到了比较满意的结果。     

往复式注水泵振动监测判断标准的研究制定

为对往复式注水泵进行状态监测与故障诊断,研究制定了往复式注水泵的振动监测判断标准,通过1台新泵的台架试验和注水站6台泵的测试分析,确定了监测布点方案,测量参数,分析频率,各测点振动警限值,绘制了警限值表和警限值线图,本判断标准的制定为往复式注水泵振动监测提供了科学的依据,具有工程实用价值。     

A new method for measuring engine rotational speed based on the vibration and discrete spectrum correction technique

This paper presents an encoder-less method for measuring the rotational speed of a reciprocating engine. The proposed method obtains the rotational speed of the engine from the lowest harmonic frequency component of its vibration signals, and uses a discrete spectrum correction technique to improve the measurement precision. Results from bench tests and tests on real engines, each having a different number of cylinders, have proven that the proposed method can achieve an extremely high precision when the engine is working in a steady-state or small speed fluctuation condition. As compared to the encoder-based method for measuring engine rotational speed, which is often found in literatures, the proposed method uses a straightforward hardware which is easy to install, and is particularly suitable for use during routine inspection and maintenance of vehicles.     

试验台约束对滑动轴承动特性识别精度的影响

在滑动轴承的动特性测试中,试验台参数对动特性测试精度有重要的影响。以某倒置式轴承动特性试验台为研究对象,基于轴承动力学正反问题,提出滑动轴承动特性系数识别精度的仿真评估方法,分析不同激振频率时试验台约束参数对轴承动特性系数识别精度的影响规律,并对激振频率和约束参数的取值范围进行优选。结果表明：在较低激振频率的条件下,当约束刚度和约束阻尼取值较小时,动特性系数的识别精度受测试误差的影响不大,随着约束刚度和约束阻尼取值增大到一定值,动特性系数的识别精度受测试误差的影响迅速增大。针对研究的试验台,选择激振频率在30~300 Hz之间,选择试验台约束刚度小于试验轴承刚度的0.3%,试验台约束阻尼小于试验轴承阻尼的7%时,能够保证较好的轴承动特性系数的测试精度。     

Bench Tests for Jackhammers: A Review

The determination of jackhammer parameters in bench tests is considered. Test procedures for determining the energy, vibration, and noise parameters of jackhammers are analyzed. This review provides context for the development of the SORP universal test bench and UIPU measuring system.     

轮胎动态实验台往复运动位移自动测控系统

往复运动位移的自动测控系统是轮胎动态实验台的核心部分，它直接影响实验台的性能。文中提出一种由磁致伸缩线性位移传感器、MAXl95A／D转换器和AT89C52单片机组成的往复位移自动测控系统。现场使用和实验表明，该系统的测量误差小于1mm，具有测量精高、可靠性好和环境适应性强等优点。     

基于航空惯性试验台交流变频驱动系统混合供电技术研究

本文以航空惯性试验台交流变频驱动系统为例,研究试验台变频驱动系统混合供电技术。变频驱动系统混合供电技术通过“储能斩波+常规变压器整流”两种供电方式为变频器提供满足要求的直流电源,本文对这两种供电电源的组成架构、控制策略进行了全面的叙述,并且后续将扩展至大功率脉冲试验台应用方向,节省了建设费用,降低了运营成本。     

液压梭阀的耐久性试验研究

针对原有梭阀工作寿命低、泄漏量大等缺点，设计了一款新的梭阀。为了验证自制梭阀的性能，在高压脉冲疲劳试验台上对原有梭阀和自制梭阀进行了对比性试验验证。试验之前，验证了梭阀加载压力和流量的正确性。试验过程中，用量杯量取了原有梭阀和自制梭阀的泄漏量。整个梭阀的台架试验相比于实际工况而言环境更加恶劣。试验结果表明，自制梭阀泄漏量低，耐久性好，寿命优于原有梭阀。     

振动标定试验台的研究设计

利用曲柄滑块机构的原理,设计了机械式振动标定试验台,该振动台可以提供标准的简谐振动,能够实现一定范围的调幅,能通过调节电机的转速控制振动台的频率。本振动台为加速度转换为位移提供重要的试验依据,为振动加速度传感器的标定提供试验平台,为零件的振动能力提供相应的数据参考。     

台式砂轮机起动时间在线检测新方法

试验研究了台式砂轮机起动过程中定子绕组电流的变化情况，找出了特有的曲线规律。首次提出了一种在出厂总检线上利用测试绕组电流从而达到检测起动时间的新方法。介绍了检测装置软、硬件基本结构。本装置几年来工作情况良好     

负载口独立控制系统主被动加载试验台振动特性分析

主被动加载试验台是对负载口独立控制系统进行主动和被动控制性能试验测试的关键设备。为了分析试验台加载过程中加载力对试验台的振动特性的影响,采用有限元网格划分软件Hypermesh对试验台整机进行了网格划分,定义了材料属性,并通过有限元仿真软件ANSYS Workbench对主被动加载试验台分别进行了静力学分析、模态分析、位移谐响应分析和加速度谐响应分析。仿真结果表明:从试验台的振动过程中的固有频率变化、振幅变化、位移响应分布、加速度响应分布、振动传动路径等可知,主被动试验台在加载试验中,将加载力的频率控制在35 Hz以内,可以避免由于加载而产生的试验台共振现象。     

Method for Jackhammer Testing on the SORP Bench

Russian Engineering Research - A method is proposed for measuring jackhammer parameters on the SORP test bench. This method may be characterized as correct and metrologically impeccable. In...     

空气弹簧液压悬置动特性及隔振特性研究

研究了具有可变刚度阻尼的发动机空气弹簧液压悬置的动特性和隔振特性。针对影响发动机空气弹簧液压悬置动特性的关键参数上液室等效体积刚度,采用理论和试验方法研究了上液室等效体积刚度的等效值,基于该等效值建立了空气弹簧液压悬置的理论模型,对空气腔开闭两种工况进行了空气弹簧液压悬置动特性的仿真和试验研究。搭建了发动机空气弹簧液压悬置系统试验台架,研究了台架各种激励频率下的空气弹簧液压悬置的隔振特性。结果表明:本研究采用的上液室等效体积刚度进行空气弹簧进行建模是正确、可行的,提高了空气弹簧建模效率和准确性;空气弹簧液压悬置在空气腔开启和关闭两种状态下,峰值动刚度增大幅值达78.5%,峰值阻尼角增大幅值达250%。台架试验表明:当台架激励频率小于25Hz时,悬置采用大刚度大阻尼;当台架激励频率大于等于25 Hz时,悬置采用小刚度小阻尼;悬置隔振率提升明显,不同频率下提升幅值达10%～67%。     

Component transfer path analysis method with compensation for test bench dynamics

In this article a component transfer path analysis (TPA) procedure is proposed. The method allows one to calculate the total system response resulting from a subcomponent's source excitation. It is based on the knowledge of the frequency response functions (FRFs) of the total system and on a measurement of the stand-alone subcomponent on a test bench. As the true source excitation, for example an engines combustion, is not measurable, equivalent forces at the subcomponent interface are found. The equivalent forces are multiplied with the total system FRFs from the subcomponent interface to response nodes of interest. The resulting responses at and in front of the subcomponent interface are shown to be physically exact for linear, time invariant and stationary operating systems.However, for the method to succeed, the source forces will have to be independent of the global dynamics. In addition, the test bench needs to be rigid in the frequency range of interest. This is typically hard to achieve for analysis in the mid frequency range (100–1000 Hz in vehicle acoustics). Therefore, a way to compensate for the test bench dynamics is also discussed. It is shown that one needs the receptance matrix of the free component at its interfaces and the operational motions of the interface on the test bench. Knowledge of the test bench dynamics is not needed.Measuring excitation and response at the source interface may not be feasible in practice due to space restrictions. In this case, the proposed TPA method can be extended with substitute nodes on the subsystem which are reachable on the test setup and the total system. With the knowledge of the free subcomponent FRFs, physically exact responses at and in front of the gearbox interface can also be calculated.     

计算机辅助螺栓联接实验装置的设计

本文对传统的LZS-85型螺栓连接实验装置进行了改造,完成了计算机和实验装置之间的联接,编制了数据采集软件,为今后更好地进行螺纹连接实验打下了基础。     

石墨水润滑动压推力轴承的起飞转速及磨损的量化研究

针对极端工况下石墨水润滑动压推力轴承的起飞转速及磨损难以量化的问题,利用核主泵半尺寸轴承对量化方法展开研究。建立了石墨水润滑可倾瓦推力轴承模型,采用摩擦副粗糙度作为衡量指标计算了理论起飞转速,并与起飞转速台架试验结果进行了对比;使用质量磨损率作为衡量磨损量化标准,进行了小试样试验和启停台架试验,二者结合对石墨不锈钢摩擦副进行了研究。研究结果表明：理论计算的起飞转速与起飞台架试验结果的误差为20 %,证明理论计算方法具有一定的可行性;小试样试验与启停台架试验的误差为39.2 %,小试样试验可对台架试验的结果进行预估或评价,二者的试验结果可以进行综合分析以指导理论计算。     

基于谐振式MEMS传感器的仪表开发关键技术

针对基于谐振式MEMS传感器开发数字智能仪器仪表的高精度、快响应频率测量技术展开研究。以一谐振式MEMS气压传感器为开发样件,其差分输出是两路40～70 kHz之间的正弦频率信号。对传统的频率测量方法进行阐述分析,提出一种新的结合传统测频方法各自优点的频率检测方法。设计实现相关软、硬件,搭建测试系统,实验结果表明该测频方案针对40～70 kHz的频率信号误差小于±0.02 Hz,响应时间为1 s以内。     

Firmware realization of the bench for testing electronics of drift chambers of the CBД-2 setup

A construction and functions of the bench for checking the electronic equipment for recording signals from drift chambers, which is composed of 1500 channels for measuring nanosecond time intervals, is described. The special attention is paid to realizing the software-based functions of data control, observation, and monitoring.     

高测速双纵模双频激光干涉仪系统的研究

以合适频率的高稳定度电子振荡器信号分别与双纵模热稳频双频激光干涉仪输出的频率过高的测量和参考信号混频,将信号载波频率降至计数器允许频率范围内,得到全交流的高测速双纵模双频激光干涉仪系统。本文给出了高测速双纵模双频激光干涉仪系统光路框图和信号处理框图,并给出了振荡器频率选择的基本公式。所研制系统纵模间隔约728MHz,计数器选用最大允许计数频率10MHz的82c54,振荡器为频率为723MHz的JE0723型介质振荡器。在3m激光测长机上的实验证实:系统分辨率为0.32μm时,最大允许测量速度可达1300mm/s,能满足各种高速运动设备的检测及标定需求。