Optical-fibre flowmeter

A technique is described for the measurement of fluid flow using an optical-fibre transducer. The flowmeter has no mechanical moving parts and causes no pressure drop in the liquid stream. The optical system and the detection electronics are intrinsically very simple. Results from a prototype meter are given, and improvements in this design, particularly in the turbulence characteristics of the meter tube, should improve measurement accuracy to an estimated ±5%.     

Integrated direction-sensitive flowmeter

Careful investigation of the cooling of a heated body in a flow shows that in integrated silicon technology a very small flowmeter can be made with a well defined direction-sensitive response over a wide range of flow speeds.     

涡街流量计的二次仪表设计

流量测量在经济建设和社会生活的各个方面得到广泛的应用.涡街流量计通常由流量传感器(又称一次仪表)和流量显示器(又称二次仪表)组成,介绍一种流量计的设计思路,给出硬件组成和软件框图.     

浮子流量检测技术的研究

浮子流量计应用于微小流体信号检测时,决定其检测精度的关键在于对浮子位置的精确检测,本设计方法通过浮子内嵌的衔铁,利用差动变压器式传感器原理,将浮子位移的变化转换为输出电压的变化以确定浮子的准确位置。文中介绍了该系统的物理模型及原理论证。     

An integrated laser blood flowmeter

We have constructed a very small and lightweight blood flowmeter using micromachining and surface mounting techniques for a wearable health monitoring system. The hybrid integrated structure of the optical system incorporates a InGaAsP-InP distributed feedback laser diode (DFB-LD) with a wavelength of 1310 nm, an edge-illuminated photodiode (PD) and a polyimide waveguide on silicon substrate (2 mm /spl times/ 3 mm). This integrated flowmeter can be positioned directly on the tissue and permits real-time monitoring of capillary microcirculation. In-vivo measurements of blood perfusion in a finger confirm the feasibility of the blood flowmeter.     

Electromagnetic inverse scattering of multiple two-dimensional perfectly conducting objects by the differential evolution strategy

Electromagnetic inverse scattering of multiple two-dimensional (2-D) perfectly conducting objects with transverse magnetic (TM) wave incidence by the differential evolution strategy (DES) is presented. The governing electric field integral equations for the scattering problem are expressed as surface integral over the cylinder contours. The cylinder contours are approximately represented by closed cubic B-splines local shape functions in local polar coordinate system. The inverse problem is to locate the cylinders and to reconstruct their shape with or without a priori knowledge of the number of cylinders. It is cast into an optimization problem and is solved using the DES. Both synthetic and real reconstructions are carried out. The reconstruction results agree with the true profiles very well. Comparison with the real-coded genetic algorithm has been carried out. It has been observed that the DES outperforms the real-coded genetic algorithm.     

Monomode fibre optic vortex shedding flowmeter

The use of a monomode optical fibre sensing element in the measurement of flow velocities by an interferometric technique is described, in which the operating principle is the flow induced oscillation of the fibre caused by vortex shedding. The system has been demonstrated to show a linear response with water flows in the Reynolds number range 100?3500.     

超声多普勒流量模拟器研究

相对传统的流量计,超声多普勒流量计测量适合于多种工况条件和液体类型的流量测量,在工业流量测量中具有广泛的应用前景。为了适应多普勒流量计性能测试和评估的需要,加快流量计的研制进程,本文通过对油田应用环境的分析,提出了基于DDS（直接数字式频率合成）技术的多普勒流量模拟器的设计。完成了硬件、固件程序及计算机软件的开发。应用...     

Fibre-optic Coriolis mass flowmeter for liquids

The letter describes a fibre-optic mass flowmeter for liquids, which is based on the Coriolis effect. The flowmeter is optically powered, and employs interferometric detection. Experimental results are presented and discussed     

基于无线通信的涡轮流量计

设计了一种基于MSP430系列超低功耗系列单片机的涡轮流量计,通过无线模块实现主从控制器之间的数据和命令传送,通信时采用了“主一从”的方案。从控制器将传感器采集到的流量信号传送给主控制器,主控制器发送命令控制从控制器的测量、阀门的开、关等动作,主控制器通过CDMA网络传送数据给控制室。流量计结构简单、轻巧、反应灵敏、安装维修方便,不需要铺设通信电缆。     

微气体流量计的模拟与优化

温差法测流量是一种新型气体流量计的基本原理，温度传感器的布置对流量计的性能影响很大。本文使用基于分子运动理论的直接模拟Monte Carlo法对这种微气体流量计通道内的气体流动进行了数值模拟，对比了有无传感器时速度场和温度场的分布，指出传感器的布置对温度场的影响很小，并根据温差分布规律提出了传感器布置的优化方案。     

基于DSP的超声波流量计的研究

超声波流量计因为具有不接触被测介质等优点,已经被不断研究并应用在许多领域,发挥了巨大的作用。设计了基于DSP,以多普勒效应为原理的超声波流量计,完成了硬件设计和软件设计。最后对FIR数字滤波器和FFT算法进行了仿真,证明了方案的可行性。     

具有温度补偿功能的超声波流量计设计

针对当前榨油设备产油量难以准确测量的问题,提出具有温度补偿的测量方案,并完成了硬件设计和软件流程图的绘制.方案采用以DSP TMS320F2810为处理核心的超声波流量计测量流量、单总线式温度传感器DS18B20采集温度,由微处理器STC89C52根据流量信息和温度信息进行补偿计算,最后得出在标准计量温度下的流量信息.     

微气体流量计的模拟与优化

温差法测流量是一种新型气体流量计的基本原理 ,温度传感器的布置对流量计的性能影响很大。本文使用基于分子运动理论的直接模拟MonteCarlo法对这种微气体流量计通道内的气体流动进行了数值模拟 ,对比了有无传感器时速度场和温度场的分布 ,指出传感器的布置对温度场的影响很小 ,并根据温差分布规律提出了传感器布置的优化方案。     

无线通信在流量计中的应用

设计了一种基于超低功耗单片机MSP430F149的涡轮流量计,运用单片机的片内定时器,捕捉涡轮传感器由于流体流过时叶片转动产生的脉冲信号,完成对流量信号的测量,通过无线数传模块传送流量数据,并且可以接收上位机的命令,来控制阀门动作。流量计结构简单、轻巧、反应灵敏、安装维修方便,不需要铺设通信电缆。     

Vortex shedding fluid flowmeter using optical fibre sensor

An optical fibre flowmeter is described which uses a single fibre mounted transversely to the fluid flow within the pipe. The fibre is vibrated by the natural phenomenon of vortex shedding, causing phase modulation of the optical carrier within. The modulation is detected at the fibre exit by the fibredyne technique, and the flow rate determined from the vibration frequency.     

电磁兼容与电磁兼容设计

电磁兼容设计通常包括系统设计/分系统和分机设计,从工程实施上考虑,需要在结构和电路设计综合采取措施。系统/分系统设计要考虑系统内部能兼容工作,更要在EMC设计前,对系统/分系统工作环境进行调查。详细论述了有效并较易采用的一些方法及注意事项。设计中应采用投资少而系统效能又高的设计方案,以减少费效比。     

相位差法超声波流量计的研制

在分析超声波相位差法测量流体流量基本原理的基础上,提出了一种利用过零检测技术测量相位差的方法,并依据此方法给出了系统模型.通过以数据信号处理器为硬件电路核心器件,实现信号的高速采集和运算,满足过零检测所需要的时间分辨率,从而提高了系统的测量精度.此外,完善了外围电路设计,提高了系统的实时性.