基于PLC的摆动摩擦试验机测控系统研究

本文采用西门子s7-200 PLC进行数据采集和过程控制,利用Visual Basic6.0编程软件开发摩擦试验机上位机的人机界面,通过调用串口通信控件MSComm的方法实现摩擦试验数据的实时采集.本系统能够实现试验机定时工作、报警处理,以及压力和扭矩的实时采集和动态显示.     

质量流量计在油品计量中的应用

本文对质量流量计在油品计量中的应用谈了几点体会：做好质量流量计的选型是关键；进行必要的温压补偿，压力补偿有在线压力补偿、固定压力补偿二种方法；正确的安装是保证质量流量计正常使用的关键；定时进行流量计标定。     

压力定时控制系统

介绍了一种新型压力定时控制系统。该系统具有上、下限压力及安全压力设定、保压时间装定、过载机械和电子保险等功能。全系统采用无触点控制，适应于在易燃、易爆环境中使用。     

变电站计量装置数据采集系统设计研究

文章首先介绍了电能量计量自动化系统的发展趋势,然后设计了数据采集系统硬件系统和软件系统。该系统设计了放置在变电站计量柜中采集终端,通过该终端根据由管理员设定的采集周期对该变电站的所有电能表的数据进行实时采集,将采集的数据存储到采集终端的数据库中,根据管理员设定的上传周期,定时向存放于营销部机房的中心服务器中上传最新数据。     

高精密延时电路在高频信号采集方面的研究

本文研究的为高频信号采集系统中的高精密延时电路,主要采用可控恒流源的方式来实现精密定时,最后实现了1ps的最小步进精度和恒流源的可控性,提高了高频信号采集的精度与速度。     

试论职业信息采集与应用

职业信息的采集非常重要。职业信息的采用，有利于就业指导，更加有利于减轻就业压力，而对于采集来的职业信息有效的利用，这对与职业指导更加重要。     

瓦斯压力对煤岩材料全应力-应变过程瓦斯渗透特性的影响

煤岩材料是典型的多孔介质材料,瓦斯压力是煤岩材料受到的内部孔隙压力.应用自行研制的煤岩材料三轴瓦斯渗流试验装置研究了不同瓦斯压力作用下煤岩材料全应力-应变过程瓦斯渗透特性的变化规律,结果表明,围压恒定时,在某一瓦斯压力下,煤岩材料全应力-应变过程曲线与渗流速度-轴向应变曲线具有较好的对应关系.理论研究表明,瓦斯气体对煤岩材料具有力学和吸附作用.围压恒定时,在一定的瓦斯压力范围内,增加瓦斯压力可增大煤样的渗透率.研究结果对预测煤岩瓦斯涌出和预防煤与瓦斯突出具有现实指导意义.     

压力式传感器校准装置的研制

开发研制了一种压力式传感器的标准装置，使压力式传感器采集的压力值得到溯源，友保证铁路运输生产中的检测、监控设备的准确可靠。     

基于足底压力传感器的不控制减重比例下步态相位识别

下肢外骨骼机器人是帮助下肢运动功能障碍患者步行训练的新手段，能够减轻医护人员的劳动强度，它常采用减重方式完成辅助训练。然而，对于地面行走减重外骨骼机器人系统而言，其减重比例随步态及穿戴方式变化而变化，因此不控制减重比例下的步态相位识别具有重要意义。通过搭建基于Arduino Mega2560板卡和单侧鞋内8个薄膜式压力传感器的足底压力采集系统，分别采集了正常行走、不控制减重比例减重带减重状态下行走时的足底压力信息，并采用神经网络算法进行步态相位识别。结果表明：在减重状态下行走与正常行走相比，左右脚压力值均出现明显下降且两侧具有对称性；足底每个压力传感器处的压力减小比例不同；采用神经网络算法对正常行走时步态相位总体识别率达到96.8%，对减重行走时步态相位总体识别率达到94.8%。研究结果表明该足底压力采集系统可以有效测量减重行走时的足底压力，为在地面不控制减重比例下减重带减重的外骨骼机器人控制策略的制定提供一定支持。     

利用高速采集系统实现角速度波动的测量

利用自行研制的高速采集系统,通过测量和数据处理软件来实现角速度波动信号的采集和处理,利用定时测角原理实现瞬时角速度的测量,并通过实验验证了该方法的可行性.     

本征正交分解技术及其在预测屋盖风压场中的应用

本征正交分解（POD）是以能量表述的随机场的最优分解，采用瑞利商概念及其极值性质推导了POD原理。根据风洞试验同步采集的风压数据利用POD技术预测了圆拱顶屋盖未布置测压点位置的风压时间序列。对预测风压包括均值、均方根值、极值在内的统计特性，时程曲线以及功率谱与实测风压作了比较。通过采用完全二次型组合法计算屋盖风致响应对所提预测方法的有效性进行了检查。     

Estimation of vapour pressure and partial pressure of subliming compounds by low-pressure thermogravimetry

A method for the estimation of vapour pressure and partial pressure of subliming compounds under reduced pressure, using rising temperature thermogravimetry, is described in this paper. The method is based on our recently developed procedure to estimate the vapour pressure from ambient pressure thermogravimetric data using Langmuir equation. Using benzoic acid as the calibration standard, vapour pressure-temperature curves are calculated at 80, 160 and 1000 mbar for salicylic acid and vanadyl bis-2,4-pentanedionate, a precursor used for chemical vapour deposition of vanadium oxides. Using a modification of the Langmuir equation, the partial pressure of these materials at different total pressures is also determined as a function of temperature. Such data can be useful for the deposition of multi-metal oxide thin films or doped thin films by chemical vapour deposition (CVD).     

一元线性回归分析方法在压力传感器数据拟合中的应用

针对压力传感器在工程测量中需要根据计量检定数据获取压力传感器输出值和所加载标准压力值之间关系的问题,采用正态检验和方差分析的方法分析了压力传感器输出电压值和标准压力值之间的特征关系。根据相关系数值的计算结果,建立一元线性回归模型。分析了一元线性回归模型的拟合优度、模型线性关系、回归系数和模型的残差。结果表明：一元线性回归分析方法能够应用于计量检定工作中的压力传感器检定数据拟合分析,这对计量检定人员研究其他类似检定数据的拟合方法具有重要的参考价值。     

High Pressure Effects on Electronic and Magnetic Properties of LaOFeAs Superconductor

The effect of pressure has been studied on structural and electronic properties of LaOFeAs high-T _c superconductor by ab initio density functional theory by using pseudopotential Quantum Espresso code. The lattice parameters and ionic positions in the ambient pressure and some high pressure up to 20 GPa have been calculated. The obtained data versus the simple scaling relation for the ionic positions and distances for mechanical pressures have been discussed. The results of band structure and magnetic moment calculations of this compound versus the applied pressure are presented in this paper. The results are compared with the other experimental and computational data in the literature.     

Uniaxial pressure dependence of the Debye temperature in metals

The electrical resistance and its temperature coefficient have been measured for a platinum foil as a function of uniaxial pressure over the pressure range 0 to 60 MPa. The measurements were performed at room temperature using the transient hot-strip method. The data are analyzed using the electrical resistivity formula within the Block-Grüneisen approximation. The pressure dependence of the Debye temperature was directly obtained from an expansion of this formula and using the basic definition of the temperature resistivity coefficient. The reliability of the experimental data was then verified using the basic definition of Grüneisen constant. Within the investigated pressure range, the analysis supports the interpretation that the change in resistance of platinum under pressure is mainly due to the change in the amplitude of the atomic vibrations that are directly related to the change in Debye temperature. The pressure dependence of resistance and the Debye temperature of the platinum were reasonably good in spite of the approximations involved.     

爆炸冲击波空中传播特征参量的优化拟合

受测试技术和测试精度影响,空气中传播的爆炸冲击波特征参量的传统经验公式存在一定的差异,文中运用LS-DYNA有限元程序,以TNT为例,计算了空中爆炸冲击波的传播过程,采用仿真计算和文献数据相结合的方法得到了冲击波超压峰值、到达时间、持续时间和比冲量的改良预测公式;把空气中传播的冲击波分为升压阶段和降压阶段两部分考虑,以冲击波的各特征参数对冲击波的压力时程曲线进行了预测。结果表明,改良预测公式与试验数据较为吻合,且比早期的经验公式更为精确。运用这些新预测公式,可以对空中爆炸的冲击波特征参数和传播特性进行有效地预测。     

Neural Network Burst Pressure Prediction in Composite Overwrapped Pressure Vessels Using Mathematically Modeled Acoustic Emission Failure Mechanism Data

The purpose of this research was to predict burst pressures in composite overwrapped pressure vessels (COPVs) by using mathematically modeled acoustic emission (AE) data. Both backpropagation neural network (BPNN) and multiple linear regression (MLR) analyses were performed on various subsets of the low proof pressure AE data to predict burst pressures and to determine if the two methods were comparable. AE data were collected during hydrostatic burst testing on the 15-inch diameter COPVs. Once collected, the AE data were filtered to eliminate noise then classified into AE failure mechanism data using a MATLAB Kohonen self-organizing map (SOM). The matrix cracking only amplitude distribution data were mathematically modeled using bounded Johnson distributions with the four Johnson distribution parameters – ?, λ, γ, and η – employed as inputs to make both the BPNN and MLR predictions. The burst pressure predictions generated using a MATLAB BPNN resulted in a worst case error of 1.997% as compared to ?1.666% for the MLR analysis, suggesting comparability. However, the MLR analysis required the data from all nine COPVs to get approximately the same results as the BPNN training on just five COPVs; plus, MLR analyses are intolerant to noise, whereas BPNNs are not.     

岩石深孔梯段爆破侧向破裂范围计算分析探讨

根据爆炸气体等熵膨胀理论和应力波传播理论,推导了孔壁压力计算公式,以及由应力波传播和爆炸气体引起应力状态的计算公式.同时根据现场实际资料,进行了混装乳化炸药在岩石深孔梯段爆破中的侧向破裂范围的实际计算,计算结果对实际工程有一定的参考应用价值.     

Determination of saturated vapor pressure of organic substances from the triple to critical point

Methods are given of extrapolating the saturated vapor pressure of substances of “atmospheric range” to the entire liquid phase region from the triple to critical point. The extrapolation of the pT parameters from room temperature to the triple point is performed by simultaneous processing of vapor pressure and of differences between the heat capacities of ideal gas and liquid. The liquid-vapor equilibrium in the region from the normal boiling temperature to the critical point is predicted by the law of corresponding states of L.P. Filippov using the experimentally obtained pT data and values of density of liquids. Experimental facilities are described for determining the saturated vapor pressure by the comparison ebulliometric method and for determining the low-temperature heat capacity by the vacuum adiabatic calorimetry. The methods of extrapolating the vapor pressure are tested with standard substances for which reliable pT data are available for the entire liquid phase region.     

Similarity and the formation of correlations for forced convection to supercritical pressure fluids

Investigation of heat transfer to supercritical pressure helium seems to be following a pattern like that of supercritical pressure water. The aim of the paper is to demonstrate the conditions under which heated tubes carrying variable property fluid will have similar heat transfer performance. It is shown how these conditions follow from the governing equations, and their application to the planning and interpretation of experiments is demonstrated using supercritical pressure water data. Recent experimental data and correlations for supercritical pressure helium are examined.