基于无人直升机模拟飞行平台的串口通信程序设计

在实时性要求较高的测控系统中,数据采集和处理必须同步进行,而串口通信具有连接简单、使用方便、数据传送稳定等特点,在工业实时控制系统中得到了广泛地运用。文章以Win API函数作为底层接口,运用多线程编程技术,开发了一个用于无人直升机模拟飞行平台的串口通信软件,该串口通信软件实现了飞行参数实时获取、实时数据处理及实时发送等功能。实际应用中获得了良好的效果。     

容栅技术的几种扩展应用

鉴于容栅技术大部分仪应用在数显卡尺等有限方面的现状,简述了容栅技术的几种扩展应用.对容栅式的雨量计、容栅式数显扳手、容栅式汽车轮胎充气枪,倾角仪、硬度计等几种扩展应用做了简要的分析,分析认为容栅技术可以在各种领域得到广泛应用.     

Impedance mapping of particulate multiphase flows

Multiphase flows occur in many operations in the chemical, petroleum and power generation industries, which cover both multi-component and multiphase situations, such air–water, solid–water, steam and air–oil–water as well as their combinations. Due to the correlation of the multiphase and independence of each phase, the correct measuring of multiphase flow, in terms of concentration, local velocity and mass flow rate, is an extremely challenging task. Electrical resistance tomography has been used for visualisation of the concentration profiles and characterisation of fluid dynamics in particulate two-phase systems that have impedance contract between the main fluid and the second phase fluid or component clusters. This paper reviews the author’s and his colleagues’ previous and current work on electrical resistance tomography, particularly on sensing strategies, data collection systems and image reconstruction algorithms. Recent applications on the characterisations of mixing processing, solid–water and the control of a bubble column are introduced.     

多传感器数据融合技术在动态称重系统中的应用

利用多传感器数据融合技术,通过对超声波传感器、测速传感器、电容传感器以及称重传感器测得的物料质量数据进行数据融合,大大提高了称重系统的测量精度,得到受环境干扰因素更小、精度更高的有关物料的测量数据。仿真结果表明,该方法在数据处理的精确性和稳定性方面都得到改善,可以有效地减小噪声、振动、电磁干扰等环境因素对动态称重系统测量的影响。     

一种新型的电容传感器──基于边缘效应原理的传感器

本文介绍了一种新型的电容传感器。它不同于以往的平行板式电容传感器,而是利用边缘场效应的原理,设计出的具有宽的静动态测量范围(mm级)和高精度的测量仪器。它适用于自动化加工过程中的实时测量,具有快速、稳定和小尺寸的特点。文中对这种测量方法的原理,数学推导及实验进行了详细地描述。实验结果表明:这种边缘场电容传感器具有广泛的应用范围。     

A procedure for correcting for the effect of fluid flow temperature variation on the response of capacitive void fraction meters

In gas–liquid flows through test loops, the fluid temperature increases, causing a change in the dielectric properties, mainly of the liquid component, which interferes with the response of capacitive void fraction meters. This phenomenon causes, for example, deviations of about 4% in the meter response for each 10 ^∘C variation of temperature in the air–water flow. In this work, a simple procedure is proposed for correcting for the response of capacitive void fraction meters being affected due to the flow temperature being different from the calibration temperature. Static and dynamic tests were performed on a capacitive void fraction measuring system with double-helix electrodes. The results showed the effectiveness of the proposed compensation technique, which allowed a significant reduction of the measurement deviations.     

High-precision Coriolis mass flowmeter for bulk material two-phase flows

For measuring or dosing purposes in gas/solid two-phase flows (non-pressurized and pressurized systems) a mass flux measurement device based on the Coriolis principle has been developed. The Coriolis flowmeter developed is applicable for on-line measurements of the mass flux, showing a fast response time to load variations and measuring accuracies of ±1% of the actual measured value. The Coriolis flowmeter was successfully tested in pilot and industrial plants. Different granular materials, such as coal dust, quartz sand, feldspar, plastic granulates and foodstuffs have been measured already. In practice, the Coriolis flowmeter has shown reliable operation in various applications in process engineering. The integration of the Coriolis flowmeter into advanced control systems for feeding or dosing purposes opens new possibilities for on-line control and exact dosing of gas/solid two-phase flows.     

Modeling and development of an ANN-based smart pressure sensor in a dynamic environment

In many engineering applications, a capacitive pressure sensor (CPS) is placed in a dynamic environment in which the temperature variation is quite large. Since the response characteristics of a CPS are highly nonlinear and temperature dependent, in such situations, complex signal processing techniques are needed to obtain correct readout of the applied pressure. We have proposed an artificial neural network (ANN)-based smart capacitive pressure sensor, whose response characteristics can be estimated within an accuracy of ±1% error over a wide variation of temperature starting from −50°C to 150°C. This modeling scheme automatically takes care of all the nonidealities, such as, nonlinearity, offset, gain and temperature dependence, of the sensor. A novel idea of automatic collection of temperature information and its feeding into the ANN model is also proposed. In the practical implementation of this scheme, the hardware complexity poses a serious impairment. Since the tanh() functions are needed for implementation in the ANN-based model, to reduce the hardware requirement, we provide a simple scheme for computation of tanh(). Sensitivity analysis of the model with respect to the finite word-length constraint on the final stored weight values, and number of terms used in the implementation of tanh() function, have been carried out. A microcontroller-based implementation scheme for the ANN-based model is also suggested.     

3种型号湿敏电容传感器温度和迟滞特性的分析比较

为掌握目前气象行业使用的湿敏电容湿度传感器的测量准确度、迟滞误差、温度系数等测量特性,文章对3种不同型号的湿度传感器进行了测试,对不同温度点下传感器的相对湿度测量示值误差和迟滞误差进行了分析和比较,测试和分析结果表明不同传感器的温度和迟滞特性有较大的差异。其分析比较的结果对湿度传感器的选择和使用具有参考价值。     

Ultrasonic fingerprint sensor in underglass prototype using impedance mismatching

Fingerprint imaging is a powerful tool in biometric identification systems. There are several methods for measuring fingerprints, such as optics, capacitive, and ultrasonic methods. The previous ultrasonic imaging techniques have been available in immersion systems which require the hands to be put into water. Also, pulse-echo system in dry condition has coupling layer which is similar acoustic impedance to human tissue or high impedance materials based on waveguide. For fingerprint imaging in the dry state, we propose an ultrasonic imaging technique in underglass by using the impedance mismatch between the fingertip and the solid plate. We present the image results according to the plate material such as acrylic, glass and PDMS. In addition, simulation results based on small 2-D array transducers in a near field suggest the feasibility of compact and fast fingerprint scanning system. Therefore, this work presents feasibility of ultrasonic pulse-echo fingerprint sensing method for dry hand.     

Dynamic identification of electrostatically actuated MEMS in the frequency domain

Micro-electro-mechanical systems (MEMS) are commonly constituted by suspended structures such as beams and spring-supported plates and are applied in a wide range of fields such as sensing, optics, radio frequency communications, fluidics, biology, etc. The components that form the basis of MEMS devices are often actuated using electrostatic capacitive strategy, and performances are improved by the micro-scale dielectric gap between the electrodes. The dynamic dimensioning and characterization are made more complicated by the nonlinearity of the electrostatic actuation and by the electro-mechanical coupling, which involves the capacitive force and the elastic reaction of the structure. The dynamic characterization is affected by specific problems related to electro-mechanical coupling, which need a dedicated approach. Some of the effects that take place during the dynamic tests on electrostatically actuated MEMS are studied in this work and are described using compact analytic models; using the proposed approaches, results of experiments in the presence of electro-mechanical coupled domains can be predicted and interpreted correctly. Structural properties such as residual stress or strain dependent on the fabrication process may influence the measurements in both, the static and dynamic fields. The goal of this study is to describe the most common experimental problems related to the dynamic characterization of electrostatically actuated microsystems; theoretical approaches that are able to describe the effects involved are proposed to predict and interpret experimental results.     

Accuracy of cross correlation velocity measurements in two-phase gas–solid flows

The paper presents a detailed discussion of the errors of quantisation and sampling (conversion) caused by A/D converters and brought up for discussion on the basis of some original formulae derived. These converters are implemented in analogue–digital parts of measuring systems designed and produced to be in operation according to the cross correlation method of measurement of mean flow velocity of solid particles especially in pipelines of pneumatic transport. The discussion is based on an analysis of a real measuring system in which electrostatic flow probes were used to detect the smallest changes in charge carried by solid particles in pipes of pneumatic transport and in the air during their two-phase gas–solid flows. In the cross correlation of signals induced in electrostatic flow probes a non-intrusive electrostatic method is employed which is based on the phenomenon of electrostatic induction brought about by the time-varying charge of particulates in conveying pipes or by the so-called electrostatic flow noise. The conclusion of the discussion can be spread among other kinds of cross correlation method including the capacitive or electromagnetic methods based on the types of sensors named after the names of the methods. Certain excerpts in the paper are taken from or based in part on some passages from the author's monograph (Gajewski, 2010 [1]).     

Concentration and pressure measurements of dense sand and gravel multiphase flows under transient flow conditions in a vertically oriented closed conduit — Assessment of system and sensor performance

The hydraulic transport of sediments in sediment–water multiphase mixtures is an important process in nature and many industrial applications. The flows are characterized by complex transient phenomena, in which the overall system scale and the particle scale are equally important. Experimental research into dense mixture flows is focused on measurement of flowrates, differential pressures and concentrations of the suspended sediments.Concentration measurements are especially challenging in the case of coarse particles (beyond millimeter size scale) flowing in dense mixtures, limiting the range of available sensors for accurately measuring the in-situ solids concentrations. For the investigation of transient processes, a quick sensor response is required, which makes concentration measurement based on mixture conductivity an interesting option.This study is focused on combined concentration and pressure measurements in dense sediment–water mixtures with coarse particles in a vertically oriented closed conduit, using differential pressure sensors over the vertical segments and conductivity probes for measuring the mixture concentration. We experimentally investigated the dispersion process of an initially densely packed batch of sand and gravel by measuring the concentration on different segments of the conduit, resulting in data on mixture wall shear stresses for different sand and gravel mixtures and data of attenuation of concentration gradients in vertical upward and downward flow, in the conduit horizontal top section and in the centrifugal pump.We describe in the detail the sensor calibration and data processing method, giving a best practice for the use of conductivity concentration sensors in dense coarse particle mixtures, and we suggest a novel method for analysis of density wave amplification and attenuation based on concentration measurements in general, which allows for the detailed analysis of transient multiphase flow phenomena at pipe system component level.     

Photogrammetry and laser scanner technology applied to length measurements in car testing laboratories

The important reforms developed in vehicles require geometrical measurements in car testing laboratories. They are usually performed by using coordinate measuring machines in gantry configuration or laser trackers. The uncertainty values obtained from this instrumentation is very low in comparison with the high tolerances required by the standards applied to the measurements, UNE 26-192:1987 and ISO 612:1978. This fact, together with the requirements about economical investments, lead to the research of the suitability of different metrological systems and procedures.Photogrammetric and laser scanning systems require lower economical investment so they can be useful in car testing laboratories. In this work, two of these systems are tested to verify their capability to fulfil the parameters and tolerances required for the standards UNE 26-192:1987 and ISO 612:1978. The uncertainty evaluation of these techniques is performed using a standard artefact based of five delrin spheres which is previously calibrated using a coordinate measuring machine.Geometrical parameters height, length, width, front track and wheelbase are measured from a car using the techniques under study, and MATLAB software aided in data processing. The results obtained are compared with the geometrical data previously provided by the manufacturer and the tolerance and uncertainty intervals defined by the standards. Both techniques demonstrate their metrological capacities for the performed measurements and required tolerances, although photogrammetry appears as a more advisable technique. Photogrammetry requires lower economic investment and offers higher portability, although human operator requires more expertise for target positioning and illumination controlling.     

An efficient correction storage scheme for unsteady flows

An efficient correction storage scheme on a structured grid is applied to a sequence of approximate Jacobian systems arising at each time step from a linearization of the discrete nonlinear system of equations, obtained by the implicit time discretization of the conservation laws for unsteady fluid flows. The contribution of freezing the Jacobian matrix to computing costs is investigated within the correction storage scheme. The performance of the procedure is exhibited by measuring CPU time required to obtain a fully developed laminar vortex shedding flow past a circular cylinder, and is compared with that of a collective iterative method on a single grid. In addition, some computed results of the flow are presented in terms of some functionals along with measured data. The computational test shows that the computing costs may be saved in favor of the correction storage scheme with the frozen Jacobian matrix, to a great extent.     

电容式压力传感器的厚膜集成化研究

采用厚膜传感技术研制电容式感压元件,并通过厚膜混合集成技术将信号处理电路集成在感压元件上成为一体,进行电容式压力传感器的厚膜集成化研究。结果表明：研制成的新型厚膜电容式集成压力传感器,线性达到0．5％,迟滞小于0．5％,具有重复性好,受分布电容,寄生电容影响小,精度高,抗过载,耐腐蚀等特点,对厚膜感压元件,信号处理电路的设计与平面化加工以及集成化等进行了介绍,并对集成化中相关工艺,兼容性及性能进行了讨论。     

Time-dependent characteristics of the nonequilibrium condensation in subsonic flows

High-speed moist air or steam flow has long been of important subject in engineering and industrial applications. Of many complicated gas dynamics problems involved in moist air flows, the most challenging task is to understand the nonequilibrium condensation phenomenon when the moist air rapidly expands through a flow device. Many theoretical and experimental studies using supersonic wind tunnels have devoted to the understanding of the nonequilibrium condensation flow physics so far. However, the nonequilibrium condensation can be also generated in the subsonic flows induced by the unsteady expansion waves in shock tube. The major flow physics of the nonequilibrium condensation in this application may be different from those obtained in the supersonic wind tunnels. In the current study, the nonequilibrium condensation phenomenon caused by the unsteady expansion waves in a shock tube is analyzed by using the two-dimensional, unsteady, Navier-Stokes equations, which are fully coupled with a droplet growth equation. The third-order TVD MUSCL scheme is applied to solve the governing equation systems. The computational results are compared with the previous experimental data. The time-dependent behavior of nonequilibrium condensation of moist air in shock tube is investigated in details. The results show that the major characteristics of the nonequilibrium condensation phenomenon in shock tube are very different from those in the supersonic wind tunnels.     

电网电容电流外加信号单频测量法的研究与应用

针对高压电力系统发生单相接地时,流经故障点的电流急剧增加,产生很强的间隙弧光接地过电压问题,对电网电容电流外加信号测量控制器的方法进行了详细的分析,充分论证了测量电网电容电流的必要性,对电网电容电流外加信号单频测量控制器的方法进行了研究,将外加信号单频测量法的原理计算分析与其他测量方法进行了比较。研究结果表明,电容电流外加信号单频测量法具有测量准确,特别是电网系统阻尼大,回路Q值低或位移电压很小时,更能显示外加信号单频测量法的优势,为进一步进行优化电网电容电流测量法的设计与应用奠定了基础。     

Integration of close range photogrammetry and expert system capabilities in order to design and implement optical image based measurement systems for intelligent diagnosing disease

In medical applications and disease diagnosis devices, image is considered as a tool for measurement and data acquisition. Most of the imaging methods usually used in medical applications are invasive and have several side effects on human body. So, other types of image based measurement systems should be developed for medical applications. The systems must be able to use the images captured in visible part of the electromagnetic spectrum. In this research a new image based disease diagnosis method has been developed which uses optical images for measuring required symptoms. In the systems which are implanted based on the suggested method measurement capabilities of close range photogrammetry and decision making ability of expert system are integrated. The integrated system can be used for the diseases whose symptoms are visible or appear as deformations out of body and around the affected area. For evaluation of the suggested method, an integrated system has been designed and implemented for intelligent diagnosing foot deformity.