An investigation of quartz type pressure transducer behavior under continuous pressure conditions and metrological characterization

In this work the behavior of high accurate quartz based pressure transducer under the continuous pressure conditions was investigated and metrologically characterized. Paroscientific digiquartz pressure transducer which belongs to the pressure laboratory of INRIM was chosen as a device. First measurements were realized in INRIM and UME in 2005. Two different measurement procedures were applied. The pressure was applied at each pressure points approximately during 25 min to observe the behavior of transducer under applied continuous pressure conditions. The results of standard calibration procedure were compared with the results of applied continuous conditions procedure. The same measurements were repeated in INRIM and UME in 2010 to compare the results taken from 2005 to 2010 and the long term stability was evaluated.     

Air velocity and flow measurement using a Pitot tube

The accurate measurement of both air velocity and volumetric airflow can be accomplished using a Pitot tube, a differential pressure transducer, and a computer system which includes the necessary hardware and software to convert the raw transducer signals into the proper engineering units. The incorporation of sensors to measure the air temperature, barometric pressure, and relative humidity can further increase the accuracy of the velocity and flow measurements. The Pitot tube measures air velocity directly by means of a pressure transducer which generates an electrical signal which is proportional to the difference between the pressure generated by the total pressure and the still air (static pressure). The volumetric flow is then calculated by measuring the average velocity of an air stream passing through a passage of a known diameter. When measuring volumetric flow, the ‘passage of a known diameter’ must be designed to reduce air turbulence as the air mass flows over the Pitot tube. Also, the placement of the pitot tube in the passage will influence how accurately the measured flow tracks the actual flow through the passage. Calibrating the measurement system in a wind tunnel can further increase the accuracy of the velocity and the flow measurements. This objective of this paper is to provide the field engineer with single, concise source of information on flow measurement using a Pitot tube.     

Ferrofluids flow transducer for liquids

Water, being a limited and vulnerable natural resource, must be protected and economically administrated. A correct administration requires, among other things, flow measurements in order to control water consumption. Flowmeters whose characteristic equations are based on a pressure drop are generally non-linear, the flow measured not being proportional to the pressure drop. The flowmeters mostly used are those having local hydraulic resistance. Usually the local hydraulic resistance for liquid flows is obtained by decreasing the flowing section as, for example, in the Venturi tube. Although Venturi tubes have a high reliability, their disadvantages consist in the need for accurate manufacture, high price and the difficulty of replacement. These drawbacks may be avoided by realizing a flow transducer with a straight tube and a magnetic liquid manometer. In this context we present, for the first time, the operating principle and the “voltage–flow” characteristic curve of an inductive ferrofluids flow transducer for water. The transducer uses the properties of the magnetic liquid and has no moving parts (components). It can be used in steady flow conditions. The device can be adapted practically to any flow range by using a straight pipe of suitable section and an adequate U-tube manometer.     

一种石油生产永置式地面井口持水率动静态测量装置研究

为满足采油地面井口多相流持水率测量的实际要求,本文结合电导动态测量与筒状电容静态测量技术,研制了一种永置式石油生产地面井口多相流持水率动静态测量装置(PDSWHMD＿SM)。具体地,文中采用有限元方法(FEM)构建了电导-电容一体式传感器(CCIS)数值模型,在此基础上对CCIS管道内流体处于流动及静止状态下分相介质的分布特性、CCIS结构参数、CCIS电学分布特性、不同多相流工况下的响应特性等进行了深入研究,最终确定了CCIS最优结构参数：H_e=90 mm、ID=30 mm、Ih_e=3 mm、H_c=375 mm、IR₁=26 mm、T_c=1 mm、H_m=56 mm,证明了其测量误差在5%以内。另外,本文以总流量5～70 m³/d,持水率50%～90%等多相流工况为例进行了实验研究,实验结果表明：研制的装置PDSWHMD＿SM持水率测量误差同样在5%以内。仿真和实验均证明了PDSWHMD＿SM具有良好的持水率测量性能。     

A purpose-built dynamometer to objectively measure static and dynamic knee torque

This paper reports the development of a purpose-built knee dynamometer (PBKD) to evaluate passive range of motion (ROM) and isometric muscle strength measurements of the knee. The PBKD uses a TorqSense rotary torque transducer and objectively measures isometric knee muscle strength in a valid and reliable manner and passive resistance to motion through range. The device and all associated instrumentation underwent dynamic and static calibration to ensure consistent and accurate measurements were obtained in terms of knee joint angular position, passive torque measures, and isometric torque measures. Eleven healthy male participants performed a knee flexion and extension task designed to evaluate knee function. The validation of the PBKD entailed measuring the consistency of measurement and accuracy of measurement. Accuracy of the PBKD was determined by comparing peak isometric muscle strength measurements against a KIN-COM machine. No significant differences were observed both passively and isometrically between cycles and between trials. This device can have widespread applications within the rehabilitation and clinical environment and could be used as a functional outcome measuring tool to distinguish pathological from non-pathological knees. The presented preliminary results indicate that reliable and accurate measurements of knee ROM and muscle strength can be obtained.     

A method for correcting discharge of boat-mounted ADCP measurements

GPS data are usually used to measure boat velocity during boat-mounted acoustic Doppler current profiler (ADCP) measurements when bottom tracking is biased by moving bed. GPS cannot provide consistently accurate boat velocity reference because of multipath errors, satellite signal reception problems, and heading errors. In addition, the computation of water velocity from an ADCP mounted onto a moving boat is a vector-algebra problem, thus the discharge calculation is subject to the compass error when GPS is used for boat velocity reference. This paper proposes a method for correcting discharge based on the idea that the discharge calculation is independent of the boat path. The processing of two sets of boat-mounted ADCP measurements integrated with differential GPS and non-differential GPS was simulated to verify the method. The results show that the proposed method performs well in both differential and non-differential GPS conditions. The relative errors range from 0.1% to 1.5% for all measurements with the mean relative errors of 0.7%. Analytical assessment of the GPS errors shows the proposed method is insensitive to the positioning accuracy of GPS, but positioning error of non-differential GPS may induce relative discharge error of more than 1% when the river or stream is narrow. On the contrary, a relatively small compass or heading error can cause a significant error in water velocity and discharge when using GPS as the boat velocity reference. Therefore, integrating a differential GPS and maintaining a slow boat speed are best practices for discharge measurement, especially for narrow streams or short boat paths.     

一种轻便高效的大直径回转支承滚道直径测量装置

研制一种新的测量大型回转支承滚道直径的检测装置.运用弓高弦长测量方法测量,用光栅精确检测弓高数据,通过显示器对测量结果实现数字输出.该装置可以实现用小装置测量大直径.文中介绍了其工作原理、结构组成等,并对该检测装置进行了误差分析.结果表明,该检测装置具有较高的检测精度.     

Measuring river velocity and discharge with acoustic Doppler profilers

Acoustic Doppler profilers and associated software packages presently are being used to measure water velocity, channel bathymetry, and river discharge. The instruments have various configurations and frequencies; choice of the appropriate instrument depends on various factors including depth, width, and sediment load of the rivers being measured. The acoustic Doppler profilers are mounted on powerboats or small remote-controlled or tethered rafts or catamarans. Profilers enable users to make fast, accurate, and economical discharge measurements on large rivers and rivers with unsteady flow conditions because of flooding or irregular releases from reservoirs. This article describes the principles of operation, application of acoustic Doppler profilers to the measurement of velocity and discharge, and calibration and verification issues.     

Measurements of blood viscosity using a pressure-scanning slit viscometer

A newly designed pressure-scanning slit viscometer is developed to combine an optical device without refraction while measuring blood viscosity over a range of shear rates. The capillary tube in a previously designed capillary viscometer was replaced with a transparent slit, which is affordable to mount optical measurement of flowing blood cells. Using a pressure transducer, we measured the change of pressure in a collecting chamber with respect to the time, p(t), from which the viscosity and shear rate were mathematically calculated. For water, standard oil and whole blood, excellent agreement was found between the results from the pressure-scanning slit viscometer and those from a commercially available rotating viscometer. This new viscometer overcomes the drawbacks of the previously designed capillary viscometer in the measuring whole blood viscosity. First, the pressure-scanning slit viscometer can combine an optical instrument such as a microscope. Second, this design is low cost and simple (i.e., ease of operation, no moving parts, and disposable).     

Electric spark discharge as an ultrasonic generator in flow measurement situations

In this paper, a gap discharge approach to create acoustic signals for ultrasonic low pressure gas flow measurements is investigated. The objective is to develop an ultrasonic gas flow meter system that is capable of operation in extreme industrial environments. These environments might have extremely high temperatures (1200 °C), moisture, steam, dust, low gas pressure and large transmission distances.Most other types of ultrasonic transducers found show sensitivity to such conditions: their operation suffers, or they may even stop functioning if exposed to such environments. The development of new transducer technology is therefore crucial to allow ultrasonic flow measurements in extreme industrial environments. In this paper, the gap discharge emitter is evaluated as a candidate to be used in these applications. Its capabilities as a sound source are investigated, and its impact on flow meter performance is estimated. It can be concluded that, despite the uncertainties it introduces to a flow meter system, it stands out as a strong candidate to be used as an acoustic emitter in a gas flow meter system for extreme environments.     

Ancillary device for flow rate measurement using dye tracer technique

Dye tracer technique is a successful tool for measuring liquid flow in closed conduits and open channels. The technique is based on the continuous injection of a tracer into the flow and on the measurement of the dilution ratio. As one of the requirements, the tracer injection rate must be known and well controlled. A device was designed to obtain this control. Such device implements a volumetric flow measurement technique and provides accurate digital display readout. Experimental results indicate that the apparatus can be used to measure the injection flow rate in a range from 235 to 2000 ml min⁻¹ with a relative error smaller than 1.5% of the reading. Even with these low injection flow, the dilution method can be applied to determine the much higher flow rates typically found in domestic or industrial outfalls as well as in artificial or natural channels. This paper also presents an application of the dilution method to flow rate measurement of an industrial outfall and the uncertainty analysis associated with the obtained values. The results indicate that the main errors of discharge estimation can arise from non-steady state flow conditions, incomplete tracer mixing, uncertainty of tracer concentration and tracer injection rate measurements.     

一种永置式石油生产地面多井组单井轮巡 三相流监测装置及应用研究

为了解决传统石油开发集中计量方式难以获取单口油井油气水三相流相关参数的难题,采用流体体积和有限元分析等方法在建立该测量装置的数值仿真模型基础上对其结构参数、气液分离效果等进行了深入研究与优化,从而确定了该监测装置的最优结构参数,并研制了可以在现有集中计量环境中长期、稳定与可靠使用的一种永置式石油生产多井组单井轮巡三相流监测装置。另外,还在搭建的永置式石油生产地面多井组单井轮巡三相流多参数监测平台上开展了实验研究,实验结果表明,所研制的装置在气、液相流量5～70 m³/d,液相持水率50%～90%等混合流体下持水率、气量测量误差均小于10%,流量测量误差小于4%。仿真和实验均证明了永置式监测装置具有良好的多分相测量性能。     

The smart-orifice meter: a mini head meter for volume flow measurement

Differential pressure based flow meters generally consist of a flow restriction element which generates a differential pressure and a pressure transducer, externally piped to the restriction, which measures the flow related differential pressure. The smart-orifice mini head meter presented takes advantage of silicon technology by incorporating a differential pressure microsensor. In contrast to conventional head meters, it represents a single compact and economic device for general flow meter applications, in particular where small size is of concern. Computational fluid dynamics analyses were applied to develop a non-standard orifice design and prototypes of the smart-orifice were fabricated. The performance of the mini head meter in water flow measurement was determined in a computer supported test bench facility. It was compared to the results predicted by the simulation, as well as to a conventional head meter arrangement with externally mounted pressure transducer, including measurements with water at elevated temperature and different absolute line pressures. The results are very promising and verify the competitiveness of the smart-orifice as a mini head meter.     

基于PLC的双恒压供水控制系统设计

该双恒压供水控制系统是以PLC控制为核心,变频调速技术为基础,并结合压力传感器、变频器、水泵、继电器、接触器等组成。在此系统中,PLC将压力设定值与测量值的偏差经PID运算后得到的控制量作用到变频器,从而通过变频器控制水泵的转速调节管网的压力,实现恒压供水的目的。     

轧辊磨床在线测量装置误差分析及改进

针对轧辊磨床在线测量装置产生的原理性测量误差,提出一种新型的测量装置,阐述其工作原理,通过理论计算对两种测量误差进行比较.结果表明,改进后的测量装置可以消除现有测量装置所造成的测量误差,可提高轧辊磨削在线测量精度.     

Error separation in CMM coordinate metrology

测量形状误差是精密制造业质量控制的关键部分。坐标测量机(CMM)是自动化精确测量维度尺寸和几何形状的机器。本文选用两种类型的坐标测量机触发探针进行标准工件测量,旨在研究不同的每转波数(UPR)时不可预见的动态固有误差的影响。整个实验过程使用探针类型和探针速度参数,采用快速傅立叶变换分析实验结果,得到受CMM机械结构和探针扫描速度影响而可预见的几何误差。实验结果表明,UPR的数量在进行圆形测量时对CMM准确度水平起非常重要的作用。本文对探针系统和坐标测量机结构响应的具体误差公式也进行了假设与分析,以经验数据来预测PRISMO-Bridge-CMM在NIS中的准确度。     

Evaluation of errors of temperature measurements with the aid of a thin-layer transducer in concentrated contacts

Error analysis results from temperature measurements taken with a thin-layer transducer are presented in this paper. Errors resulting from the influence of the time constant, contact pressure and isolating layer of the transducer have been determined. The formulae which permit the calculation of temperature corrections resulting from the influence of the isolating layer of the transducer are presented. The influence of some other sources that disturb the measurements has also been evaluated. It has been found that the maximum values of the total measurement error may be high but not high enough to question the justification of the application of this measurement method.     

HY1200系列声速剖面仪

HY1200系列声速剖面仪采用环鸣法测量声速，能快速地为测深仪、声纳、水下声标等提供实时声速剖面数据，可供其有效地校正测量误差，提高水深测量精度。文章阐述了其声速测量原理，介绍了声速仪的组成、功能与操作，并对试验和应用结果进行了分析，提出了使用注意事项。     

基于ICA的动态测量误差分解重构方法

提出了利用独立成分分析（ICA）方法对动态测量误差进行分解重构的方法。详细介绍了利用ICA方法进行误差分解重构的基本算法,利用三坐标测量机和双频激光干涉仪设计了动态测量误差测量装置,并进行了实验。分别利用自适应滤波、小波分析和ICA方法对动态误差数据进行处理,分离重构线性变化、周期变化的系统误差和动态随机误差。研究结果表明,要精确分析动态测量误差和辨别误差组成成分,必须充分应用测量得到的误差总体样本进行分析。与自适应滤波、小波分析两种方法相比,利用ICA方法可以更有效地精确分离重构线性变化、周期变化的系统误差和动态随机误差。