PC-based微控器构建的新型计算机测控网络

由 PC-based可编程微型控制器构成新型的计算机测控网络 ,具有各站点可在 PC机上编程、可脱机独立运行的特点。文章论述如何构建 PC-based计算机测控网络 ,及其实现方法与编程技术 ,并给出一个已成功应用于实际的基于 RS-4 85总线的

Real time remaining useful life prediction based on nonlinear Wiener based degradation processes with measurement errors

Real time remaining useful life(RUL) prediction based on condition monitoring is an essential part in condition based maintenance(CBM). In the current methods about the real time RUL prediction of the nonlinear degradation process, the measurement error is not considered and forecasting uncertainty is large. Therefore, an approximate analytical RUL distribution in a closed-form of a nonlinear Wiener based degradation process with measurement errors was proposed. The maximum likelihood estimation approach was used to estimate the unknown fixed parameters in the proposed model. When the newly observed data are available, the random parameter is updated by the Bayesian method to make the estimation adapt to the item's individual characteristic and reduce the uncertainty of the estimation. The simulation results show that considering measurement errors in the degradation process can significantly improve the accuracy of real time RUL prediction.

A Method for Determining Surface Free Energy of Bamboo Fiber Materials by Applying Fowkes Theory and Using Computer Aided Machine Vision Based Measurement Technique

The purpose of this study is to develop a standard methodology for measuring the surface free energy (SFE),and its component parts of bamboo fiber materials.The current methods was reviewed to determine the surface tension of natural fibers and the disadvantages of techniques used were discussed.Although numerous techniques have been employed to characterize surface tension of natural fibers,it seems that the credibility of results obtained may often be dubious.In this paper,critical surface tension estimates were obtained from computer aided machine vision based measurement.Data were then analyzed by the least squares method to estimate the components of SFE.SFE was estimated by least squares analysis and also by Schultz' method.By using the Fowkes method the polar and disperse fractions of the surface free energy of bamboo fiber materials can be obtained.Strictly speaking,this method is based on a combination of the knowledge of Fowkes theory. SFE is desirable when adhesion is required,and it avoids some of the limitations of existing studies which has been proposed.The calculation steps described in this research are only intended to explain the methods.The results show that the method that only determines SFE as a single parameter may be unable to differentiate adequately between bamboo fiber materials,but it is feasible and very efficient.In order to obtain the maximum performance from the computer aided machine vision based measurement instruments,this measurement should be recommended and kept available for reference.

Method based on broadband compressed pulse superposition to measure properties of underwater acoustic materials

A method is proposed for the measurements of the performances of underwater acoustic finite sized large area material samples in a free field by using broadband pulse compression technique. As the result of which, the low-frequency cutoff of the standard tests is obviously reduced, and the broadband measurements are also realized. The experimental system provides measurements of complex reflection and transmission coefficients at continuous frequency points. From the data one can obtain the following acoustic parameters: echo reduction and insertion loss, absorption and attenuation coefficients, etc. The measurements are performed for two actual panels with the size 1 m x 1 m in the frequency range from 2-20 kHz.

Measuring method for micro-diameter based on structured-light vision technology

Based on structured-light vision measurement technology, we study a measuring method for microdiameter. The measurement principle and mathematical model are described. A novel grayscale barycenter extraction algorithm along the radial direction is proposed, which can precisely gather the image coor- dinates of the ellipse-shaped light-stripe centers. The accuracy of the measurement result shows marked improvement by using the algorithm. The method executes circle fitting to the measured three-dimensional （3D） data using linear least square method, which can acquire the diameter, surface profile, and other information of the object effectively. On the scene, a line-structured light vision system using the presented method is applied to measure the curvature radius of metal blades. Experimental results show that the measurement precision of the system is higher than 2 μm.

A lattice measuring method based on integral imaging technology

Aiming at the problem that the lattice feature exceeds the view field of the scanning electron microscope(SEM)measuring system,a new lattice measuring method is proposed based on integral imaging technology.When the system works,the SEM measuring system is equivalent to an integral image acquisition system.Firstly,a lattice measuring method is researched based on integral imaging theory.Secondly,the system parameters are calibrated by the VLSI lattice standard.Finally,the value of the lattice standard to be tested is determined based on the calibration parameters and the lattice measuring algorithm.The experimental results show that,compared with the traditional electron microscope measurement method,the relative error of the measured value of the algorithm is maintained within 0.2%,with the same level of measurement accuracy,but it expands the field of view of the electron microscope measurement system,which is suitable for the measurement of samples under high magnification.

Software Measurement Methods: An Analysis of Two Designs

In software engineering, software measures are often proposed without precise identification of the measurable concepts they attempt to quantify: consequently, the numbers obtained are challenging to reproduce in different measurement contexts and to interpret, either as base measures or in combination as derived measures. The lack of consistency when using base measures in data collection can affect both data preparation and data analysis. This paper analyzes the similarities and differences across three different views of measurement methods (ISO International Vocabulary on Metrology, ISO 15939, and ISO 25021), and uses a process proposed for the design of software measurement methods to analyze two examples of such methods selected from the literature.

Absolute surface form measurement of flat optics based on oblique incidence method

In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the absolute surface shape of the test flat. By adding two sets of measurements, the absolute surface error of the interferometer＇s reference flat can be obtained. The new method can not only calibrate the reference flat error of interferometer, but also provide the absolute measurement method for high precision optical components applied in high power laser systems.

An objective method for color vision deficiencies measurement based on visual evoked potential

The equi-luminance of color stimulus in normal subjects is characterized by L-cone and M-cone activation in retina. For the protanopes and deuternopes, only the activations of one relevant remaining cone type should be considered. The equi-luminance turning curve was established for the recorded visual evoked potentials (VEPs) of the luminance changes of the red and green color stimulus, and the position of the equi-luminance was used to define the kind and degree of color vision deficiencies. In the test of 47 volunteers we got the VEP traces and the equi-luminance turning curves, which was in accordance with the judgment by the pseudoisochromatic plate used in clinic. The method fulfills the objective and quantitative requirements in color vision deficiencies test.

Current measurement method based on magneto-optic rotation effect

Aiming at the approximate measurement of magnetic rotation angle in optical current sensor based on light intensity detection mode,this paper proposes a current measurement method based on triangular constant transformation to reconstruct magnetic rotation angle,so as to avoid the large current measurement error caused by the approximate measurement of the magnetic rotation angle.By extracting the direct current(DC)component and the alternating current(AC)component of the light intensity signal detected by the photoelectric detector(PD),the sine signal containing the magnetic rotation angle is directly obtained by dividing the two components,and then the triangular identity transformation method is used to linearly demodulate the magnetic rotation angle and reconstruct the current waveform.The experimental results show that the relative error of current measurement does not exceed 1.40%in the current range of 0.05—0.50 A,which is less than the approximate linear measurement(ALM)method,and the magnetic rotation angle and the current have a good linear relationship.

Deflection Compensation Model for Flatness Measuring Roll

In flatness measuring system, the flatness measuring signal can be affected by the deflection of flatness measuring roll. The stress on flatness measuring roll was analyzed and a deflection model for the flatness measuring roll was obtained by using the influence function method. The model was developed on the basis of the deformation of flatness measuring roll in roiling process and compensation curve was obtained. The results indicated that the set curve of flatness is in good agreement with the online measured curve of flatness, and good strip flatness can be obtained.

基于时空多视图学习算法的PMU电压数据重构方法

同步相量测量装置(phasor measurement unit,PMU)具有同步性好、分辨率高、相角直接可测等优点,是实现电力系统在线实时状态感知的重要信息源。然而,由于受到设备故障、气候干扰、通信问题等因素影响,实际电网中的PMU数据容易出现数据缺失和异常等情况,这将干扰后续基于PMU数据的电网高级应用,进而影响电网状态感知和运行调度的可靠性。首先,通过分析现场实测的PMU数据,归纳出4种低质量数据情况,并且利用机理分析和相关性分析方法对系统运行状态进行辨识;然后,将多视图学习方法与电网运行机理相结合,提出基于时空信息特征融合的多视图数据初步重构算法,对PMU低质量和缺失数据进行重构;最后,结合系统不同运行状态特点,利用不同视图生成数据进行低质量数据的辨识,并提出一种基于历史数据的自适应加权的缺失数据重构方法。仿真和实测数据表明该方法能有效对PMU低质量数据进行辨识并实时重构生成,为PMU数据在电力系统中的应用提供有效保障。

首次透析前终末期肾病患者脑灰质体积减小可为认知功能提供影像学标记

目的通过基于体素的形态学测量方法,系统分析首次透析前终末期肾病(ESRD)患者的脑灰质体积变化,探讨这些变化与整体认知功能、执行功能及工作记忆功能之间的相关性。方法纳入2022年2月~2024年1月在本院就诊的拟行血液透析治疗的ESRD患者62例及及同期健康对照者37例,分别进行高分辨3D T1结构成像、神经心理学测试(包括整体认知功能、执行功能及工作记忆任务),采用基于体素的形态学测量方法分析两组的脑灰质体积差异,并在回归性别、年龄及受教育程度后对差异脑区灰质体积与量表结果进行Pearson相关分析。结果与健康对照组比较,ESRD组左侧中央后回、双侧颞上回、双侧中央前回、右侧颞极颞中回、左侧直回、左侧中扣带回、双侧眶部额上回、左侧颞中回、双侧海马、左侧梭状回灰质体积显著减小(P<0.001,FWE校正);ESRD组患者左侧中央后回、左侧中央前回、左侧直回、左侧中扣带回、左侧眶部额上回、左侧颞中回、左侧颞上回及左侧海马体积与蒙特利尔认知量表评分呈正相关(P<0.05);右侧颞极颞中回、左侧中扣带回、左侧梭状回及左侧颞上回体积与连线测试-A评分呈负相关(P<0.05);左侧直回及左侧眶部额上回与2-back反应时结果呈负相关(P<0.05)。结论ESRD患者存在普遍脑灰质体积减小,且与整体认知功能、执行功能及工作记忆功能密切相关,可为观察ESRD患者认知功能障碍提供影像学标记。

高参数石油基和煤基火箭煤油射线法密度测量实验研究

基于Beer-Lambert定律,采用γ射线吸收法,研制了高参数火箭煤油密度测量装置,对液态及超临界压力下火箭煤油的密度进行测量方法研究。测量温度范围293~673 K,压力范围0.3~30 MPa,密度测量结果的扩展相对不确定度为2.2%~3.2%(置信因子k=2)。选取常压、温度293 K和压力5 MPa、温度673 K的环己烷分别作为高密度和低密度标准流体,抵消了温度变化对测量装置射线吸收率的影响。通过对环己烷和甲苯密度测量的校验,验证了测量方法的可靠性和准确性。在此基础上,完成了石油基和煤基火箭煤油的密度测量,并计算了石油基和煤基火箭煤油等压热膨胀系数。利用实验数据,拟合了宽广温度压力范围内两种火箭煤油密度的Tait函数关系式,密度实验数据与方程的平均绝对偏差为0.21%,最大绝对偏差为1.32%。测量结果表明:在所测量的温度和压力范围内,煤基煤油与石油基煤油的密度值基本一致。所得密度实验测量数据为高参数火箭煤油物性及传热等研究提供了基础数据。

排污权交易对福建绿色发展效率的影响研究

绿色发展是一种基于传统发展模式的可持续发展的创新模式,提高绿色发展的关键是提高绿色发展效率。为进一步检验排污权交易政策对福建省绿色发展效率的影响,该文首先采用数据包络分析方法的超效率模型测算绿色发展效率,其次将2011-2020年未实际开展排污权交易的省份作为控制组,通过合成控制法分析排污权交易对福建省绿色发展效率的影响情况,并进行了稳健性检验。结果表明:(1)资源配置效率是导致绿色发展效率不均衡的关键因素。(2)福建省排污权交易政策的实施对绿色发展效率呈促进作用,从拟合的结果来看,2015年若未实施排污权交易,其绿色发展效率均值将比实际值有所下降。

人口老龄化对经济高质量发展影响的空间效应——基于省级面板数据

选取2012—2022年省级面板数据,运用定基极差熵权法、空间计量模型和时空地理加权回归模型分析人口老龄化对经济高质量发展的空间影响效应。研究结果表明:从全国层面来看,人口老龄化不仅促进了本地区经济高质量发展,同时对周边地区也有正向空间溢出效应;人口老龄化对经济高质量发展的影响效应存在区域异质性,东南沿海和中南部地区表现为促进作用,西部和北部地区表现为抑制作用,并且呈现出很强的空间集聚特征。

基于反向用户测量的5G基站坐标定位技术研究

该文针对基站隐藏安装场景位置工勘不准确导致定位目标用户定位精度不高的问题,提出了一种反向定位基站的方法。该方法通过测试终端向基站发起多次5G(5th Generation)测量,获取测试终端与基站之间的5G测量值往返时延(RTT,Round-TripTime),最后构建观测方程并采用最小二乘法求解得到基站的坐标位置。试验结果表明,该方法能有效获得隐藏安装场景中基站的准确位置。

无线传感器网络人员定位算法

无线传感器网络用于人员定位给煤矿安全生产提供了有效保障。根据定位机制不同,无线传感器网络节点定位算法分为Range-based和Range-free定位算法,其中Range-based定位算法因定位精度高、误差小而在煤矿矿井中得到广泛应用。在阐述比较RSSI测距法等7种典型测距方法的基础上,分析了三边测量法等5种定位算法,指出了在选择或设计人员定位算法时应综合考虑矿井具体环境状况和特定的应用需求。

项目化教学法在“建筑工程计量与计价”实训课程中的应用研究

探讨项目化教学法在“建筑工程计量与计价”实训课程中的应用,通过将教学内容融入工程项目中,引导学生完成工程项目以实现教学目标,提高学生的实践能力和综合素质。从项目化教学法的特点和使用方法出发,将其应用于“建筑工程计量与计价”实训课程中,通过设计项目任务、实施过程和总结评价等环节,培养学生的实践技能和职业素养。最后,通过学生提问和教师反馈等方式,及时解决问题和调整教学方法,提高课程的教学效果和质量。实践证明,项目化教学法能够有效地提高学生的学习积极性和主动性,增强学生的实践能力和综合素质,为建筑行业培养更多的优秀人才。

煤矿通风阻力高效测定与应用

应用最新CZC5(B)型矿井通风阻力检测仪等仪器对双红一矿通风阻力进行测定,测定各点相关参数,并通过附带的数据处理软件快速计算出路线的阻力结果,通过分析测定结果给出煤矿阻力分布情况,提出对应降阻建议,对煤矿及时掌握矿井通风阻力状况和降低通风损耗等通风管理工作有着重要意义。