基于一种便携式测量仪的轨道车辆轮径测量方法

为快速、精准、便利地测量车轮滚动圆直径,设计了一种测量方法。此方法基于一种便携式非接触测量仪,利用激光位移传感器作为其测量传感器,通过CCD视觉检测技术和DSP技术实现了对车轮滚动圆直径的非接触测量。根据非接触测量原理的需要设计了一款车轮直径测量辅助工装,通过测量仪和辅助工装的联合运用,实现了对列车车轮直径快速、精准、方便地测量。     

圆筒形电容式粮食水分传感器的数学模型与影响因素分析

分析了粮食的介质特性,说明了圆筒形电容式粮食水分传感器的测量原理,得出了传感器电容参数与被测粮食含水量关系的数学模型.运用粮食的导电浴盆效应得出了传感器的等效电路,讨论了影响传感器电容量的因素,为圆筒形电容式粮食水分传感器的设计提供了理论依据.     

微处理器控制的电容式水分测定仪

电容法测定水分是利用样品含水量与其介电常数之间的依赖关系,通过电容传感器测量介电常数,从而确定被测样品中的水分含量。由于这种方法测量精度比较高,装置相对来说比较简单,所以在国内外引起了高度的重视,成为目前快速测定水分含量的一种重要方法。华东师范大学从1975年起先后研制成多种电容式快速水分测定仪,在国内粮食、种子、制药、外贸商检等行业中已得     

一种撮铲式水分快速测定仪

少量样品的非破坏性水分快速、准确测定,是粮食、种子、医药等行业亟待解决的关键技术之一。本文探讨了含水介质的交流导电特性,在发现含水介质导电浴盆效应的基础上提出了撮铲式水分快速测定仪的测量原理,研制成功了撮铲式水分快速测定仪。实测结果表明,仪器在准确度导、重复性好,能满足少量样品的非破坏性水分快速、准确测定需要。     

粮食水分在线测量传感器

研制了一种基于电容测量的粮食水分含量在线测量传感器。提出了一种新的传感器结构并给出了数学模型,通过理论分析和ANSYS仿真实验给出了传感器的结构参数;同时,介绍了传感器信号调理电路的软件、硬件设计。实验测量结果表明:粮食(小麦)水分含量在10%~18%时,传感器测量精度优于0.5%。传感器具有RS-485总线通信接口、体积小、粮仓内布放简单等特点,适用于粮仓在线测量。     

基于茎秆生理电容的作物生长水分测量仪

阐述了茎秆生理电容式水分传感器的工作原理,介绍了以凌阳SPCE061A单片机为主控芯片、具有语音播放功能的作物生长水分测量仪的设计.利用茎秆生理电容传感器检测作物生长的水分信号,信号经调理电路,由单片机完成转换、显示和语音播报.采用PTR8000无线数据传输模块,使测量仪可以构成多机监测系统,实现远程集中控制.实践表明系统工作稳定,数据传输可靠,数据可视化直观.     

电容式智能水分测定仪的设计

少量水分的快速、准确测定成为皮革生产过程中至关重要的环节,在研究了多种水分测定原理的基础上提出一种利用电容式传感器进行水分测定的方案,实现了一种快速的非破坏性测定方法,该方法可以广泛用于皮革、纸板等非刚性物体水分含量的检测。实验结果表明,该仪器具有测定准确度高、速度快、性价比高、操作方便的特点。     

便携电容式棉花含水量测量仪

电容器容值大小与极板间材料的介电常数有关,用聚酰亚胺湿敏材料为介质构成测量电容,电容容值反映棉花含水量,据此原理设计了棉花含水量测量仪,介绍了测量探头主要组成部分及测量原理,分析了电容测量电路,给出了测量仪电路框图和主程序流程。解决了测量仪电路框图和主程序流程。解决了电阻测量法检测干燥棉花精度不足的问题,测量仪功耗低,体积小,符合便携要求。     

基于双列阵电容传感器的气固两相流多参数测量系统

气固两相流体系是复杂的非线性动态系统,其流动过程的复杂性和随机性增加了气固两相流参数检测的难度。设计了一种基于双列阵电容传感器的硬件测量系统,该测量系统具有成本低、响应快、非侵入性和安全性好等优点,广泛应用在工业生产中。其采用Cortex-M4内核的STM32F407IGT6作为主控芯片进行微弱电容信号的采集,将采集的电容数据存储到SD卡且传送至上位机。将上位机接收的数据和SD卡中的数据进行离线分析和处理,得到固相浓度、速度和质量流量。实际使用结果表明,该测量系统测量精度较高、稳定性好,解决了传统测量仪表测量气固两相流时的弊端。     

微传感器压力测量系统

压力是应用最为广泛的物理参数之一,压力测量在工业生产中必不可少.在研究微电容传感器的基础上,分析了压力测量的工作原理,提出一种基于微电容传感器的压力测量的设计方法,给出适合该种传感器的信号检测电路和压力测量系统组成.实践表明,此设计方法具有较高的准确性和应用推广价值.     

A novel capacitive system for the concentration measurement of pneumatically conveyed pulverized fuel at power stations

A novel capacitive system for the concentration measurement of gas–solid flow in pneumatically conveyed pulverized fuel at power stations has been developed. The capacitance sensor for measuring the concentration uses source-grid sensing electrodes. An active sensor and a dummy sensor are used to form a differential configuration. In order to eliminate baseline drift, to be immune to stray capacitance, and to ensure accurate measurement under very low solids/air mass flux ratio conditions, a correlated double sample (CDS) technique and lock-in detector with closed loop are used in the interface circuit. A laboratory scale pneumatically conveyed pulverized fuel loop system incorporating facilities for calibration has been fabricated for this purpose. The test section is a vertical ceramic tube of diameter 100 mm with an upward flow direction and pulverized fuel has been used as the solid phase. Results demonstrate that the system is capable of achieving linearity within ±5% at different temperatures or moisture content.     

调幅式电容位移传感器的峰值检波电路设计

针对调幅式电容位移传感器解调过程中由系统不确定相移导致的信号解调不准确问题,提出了一种基于改进的峰值保持电路的调幅式电容位移传感测量方法。首先,分析了调幅式电容位移传感器及其检测电路的工作原理,在研究调幅信号附加相移产生机理的基础上,提出了延迟反馈式峰值保持电路,用以去除附加相移对峰值解调的影响。然后,设计并制作了调幅式电容位移传感器,并对其各个性能指标进行了测试。最后,对实验结果和误差进行了分析。实验显示,提出的峰值保持电路的输出线性度优于0.05%,制作的传感器在0～25μm内数据测量稳定性优于10nm/30min,传感器测量偏差最大值为36nm。结果表明,采用延迟反馈型峰值保持电路有效地解决了系统不确定相移带来的峰值检波不准确的问题,所制作的电容传感器满足了高精度测量的要求。     

电容式大测深绝缘纸板微水份测量传感器

介绍一种测量深度较大的电容式微水份传感器，它利用同一平面上两平行浮动电极形成的边缘电场感应被测纸板较深处的水份变化，在低频正弦驱动源的作用下，从由传感器和绝缘纸板构成的等效阻容耦合电路的输出电压中得到与绝缘纸板微水份有关的幅值和相差角，利用特定的函数关系得出绝缘纸板含水质量分数。在结构设计上充分考虑了厚绝缘纸板微水份测量的特点，使该传感器满足了灵敏度高、测量深度大、性能稳定和安装方便的设计要求：由它构成的微水份测量系统，可以用于现场干燥过程中的变压器绝缘纸板微水份检测。     

The Feasibility of Neutron Moderation Imaging for Land Mine Detection

Neutron moderation land mine detection involves irradiating the ground with fast neutrons and subsequently detecting the thermalized neutrons which return. This technique has been studied since the 1950s, but only using non-imaging detectors. Without imaging, natural variations in moisture content, surface irregularities, and sensor height variations produce sufficient false alarms to render the method impractical in all but the driest conditions. This paper describes research to design and build a prototype land mine detector based on neutron moderation imaging. After reviewing various neutron detector technologies, a design concept was developed. It consists of a novel thermal neutron imaging system, a unique neutron source to uniformly irradiate the underlying ground, and hardware and software for image generation and enhancement. A proof-of-principle imager has been built, but with a point source offset from the detector to roughly approximate a very weak uniform source at the detector plane. Imagery from the detector of mine surrogates is presented. Realistic Monte Carlo simulations were performed using the same two dimensional neutron imaging geometry as the detector in order to assess its performance. The target-to-background contrast was calculated for various soil types and moisture contents, explosive types and sizes, burial depths, detector standoffs, and ground height variations. The simulations showed that the neutron moderation imager is feasible as a land mine detector in a slow scanning or confirmation role and that image quality should be sufficient to significantly improve detector performance and reduce false alarm rates compared to non-imaging albedo detection, particularly in moist soils, where surface irregularities exist and when the sensor height is uncertain. Performance capability, including spatial resolution and detection times, was estimated.     

润滑油含水率检测电容传感器的设计及实验研究

利用油与水介电常数差别较大的特性,借助电容式传感器可测出油品含水率。设计平行板式、圆柱形、圆筒形和螺旋线式4种电容传感器,对润滑油含水率进行检测。对4种传感器检测结果进行比较,分析测量值与理论值之间的差异,阐述影响电容传感器检测精度的因素,比较4种类型传感器的分辨率。结果表明:平行板式与圆柱式电容传感器对水的分辨率相对其他2种传感器效果要好,且在高含水率时,平行板传感器效果更加明显。     

Low Cost Microwave Sensor for Moisture Content Measurement in Paper Milling Industry

The interest about RF and microwave sensors for the measurement of dielectric properties of materials during industrial processes has been growing recently. Microwave sensors are particularly attractive for their ability of performing non-invasive measurements. An interesting field of application is the real-time moisture measurement during industrial processes. A smart active sensor for measuring the moisture content of felts used in the paper milling industry and more generally of sheet-like materials, is here proposed. The sensor consists of a cavity backed slot resonator interacting with the material under test through near fields. The design aspects of the sensor and the related measuring front-end are discussed with respect to the dielectric properties of the material, and to the resonator response. The parametric sensitivity of the measuring method with the distance between the sample and the sensor surface and the sample thickness is also analyzed. An inversion procedure based on an Artificial Neural Network (ANN) approach is proposed in order to determine the moisture content of the felts. Measurements on several reference felts, with different density, thickness, and moisture content levels, ranging from dry to waterlogged state, proved the effectiveness of the proposed sensor architecture and the ANN-based inversion procedure.