Optimizing the locations of the measuring points for an online calculation of the exhaust flue-gas loss

Flue gas properties are very important for evaluation of a boilers performance. Non-homogeneity of the properties and large dimensions of flue-gas ducts require measurements with large number of measuring points to provide high accuracy of measurement results. An analysis of simpler measuring methods is presented. It is shown that high accuracy can be achieved with small number of measuring points if their positions are optimised with respect to pre-determined conditions in the flue gas duct. The methods can be used as operational measurements to monitor boilers performance and for on-line calculation of boilers efficiency.

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Zusammenfassung Messungen der Rauchgaseigenschaften sind sehr wichtig zur Bestimmung der Kesselleistung. Aufgrund der Inhomogenität der Rauchgaseigenschaften und der großen Ausmaße von Rauchgasleitungen ist die Messung mit einer großen Anzahl an Messpunkten erforderlich, um eine hohe Genauigkeit der Messergebnisse zu erzielen. Hier wird die Analyse einfacher messtechnischer Verfahren vorgestellt. Es hat sich gezeigt, daß eine hohe Messgenauigkeit mit einer geringen Anzahl an Messpunkten dann erzielt werden kann, wenn die Lage der Messstellen unter Berücksichtigung der vorausbestimmten Rauchgaseigenschaften in der Rauchgasleitung optimiert wird. Dieses Verfahren eignet sich für die Durchführung von Messungen bzw. zur Überwachung der Kesselleistung und zur Online-Berechnung des Kesselwirkungsgrades.

     

Methological support to gas-fired boiler plant

The paper discusses providing measurement and monitoring accuracy for pressures in the gas systems of boiler plant. It is shown that the errors in measuring and monitoring pressures on the basis of existing metrological support to boiler plants may exceed the limits laid down for the permissible pressure deviations at the inlet to the gas burners by large factors. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 69–71, May, 1999.     

Semi-implicit and explicit finite element schemes for coupled fluid/thermal problems

A comparative investigation, based on a series of numerical tests, of two purely explicit and one semi-implicit finite element methods used for incompressible flow computation is presented. The ‘segregated’ approach is followed and the equations of motion are considered sequentially. The fundamental concepts and characteristics of the formulations and the solution methodology used are described in technical detail. Various modifications to Chorin's projection algorithm are investigated, particularly with respect to their effects on stability and accuracy. The stability of the semi-implicit method is shown to be less restrictive when compared to the explicit methods as the Reynolds number increases. At large time steps the artificial viscosity is also reduced and higher accuracy is obtained. The performance of the methods discussed in this paper is illustrated by the numerical solutions obtained for the cavity flow and flow past a rearward-facing step problems at high Reynolds numbers, and free convection flow problem at high Rayleigh numbers. It is shown that the semi-implicit method needs fewer iterations than the explicit methods, and the accuracy of the present methods is guaranteed by comparison with the existing methods.     

基于距离约束的关节式坐标测量机蛙跳测量方法研究

针对关节式坐标测量机(ACMM)在大尺寸工件的检测过程中测量范围有限且误差较大的问题,提出了一种基于距离约束的ACMM的蛙跳测量方法。在ACMM进行坐标转换的过程中,利用蛙跳球作为公共基准点,用高精度的三坐标测量机对蛙跳球之间的空间位置关系进行标定。在计算坐标转换参数的过程中,将任意两蛙跳球之间的位置关系作为距离约束条件,消除测量过程中产生的粗大误差并优化坐标转换模型的参数,以提高坐标转换精度。实验结果表明:距离约束能够有效地提高坐标转换参数的精度,同时增加公共基准点的个数会较大地提高蛙跳测量精度。     

纳米压痕仪和激光超声技术检测薄膜弹性模量

在薄膜材料的力学性能测定中,弹性模量是衡量材料软硬程度的重要指标。为了测定弹性模量,本文选取不同种类和厚度的金属薄膜材料,采用纳米压痕技术(nanoindentation)和激光超声技术(laser-acoustics)两种测试方法相互比较,以确保测试的准确性。两种方法在膜厚较大的试样测试中得到了大致相符的试验结果,相对误差最小达到2%。     

单模太赫兹半导体激光器高精度调谐特性研究

大量物质的特征吸收谱在太赫兹范围内,因此近年来太赫兹光谱应用的发展备受关注。相比于现有的商业光谱仪,基于可调谐单模激光器的光谱测量方法具有高精度和高光谱获取速度的优势。太赫兹量子级联激光器是可调谐激光源的理想选择。在利用其实现光谱测量前,需对其调谐特性进行研究,但是现有测量方法受到精度限制。研究发现,利用太赫兹量子级联光频梳和单模激光器之间的拍频,可在微波波段得到对应的拍频信号。当调谐单模激光器时,拍频信号会发生相应的频移。因此,结合量子级联激光器的自探测,利用频谱分析仪测量拍频信号的频移情况,可以实现对单模激光器调谐的高精度测量。最终得到所测太赫兹单模激光器的调谐速率为53 MHz/K（温度调谐）和2.7 MHz/mA（电流调谐）。     

Material characterization and interfacial boundary identification by solving an inverse elasto statics boundary elements problem

An inverse geometry problem of identifying simultaneously two irregular interfacial boundaries along with the mechanical properties of the interface domain located between the components of multiple (three) connected regions is investigated. A discrete number of displacement measurements obtained from a uniaxial tension test are used as extra information to solve this inverse problem. A unique combination of global and local optimization method is used, that is, the imperialist competitive algorithm (ICA) to find the best initial guesses of the unknown parameters to be used by the local optimization methods, that is, the conjugate gradient method (CGM) and the simplex method (SM). The CGM and SM are used in series. The performance of these local optimization methods is dependents on the initial guesses of the unknown boundaries and the mechanical properties, that is, Poisson’s ratio and Young’s modulus, so ICA provides the best initial guesses. The boundary elements method is employed to solve the direct two-dimensional (2D) elastostatics problem. A fitness function, which is the summation of squared differences between measured and computed displacements at identical locations on the exterior boundary, is minimized. Several example problems are solved and the accuracy of the obtained results is discussed. The influence of the value of the material properties of the subregions and the effect of measurement errors on the estimation process are also addressed.     

炸药爆速的连续测量技术研究

爆速是研究炸药性能的重要指标,虽然传统的爆速测量方法操作简单,但是由于测量点少、精度低,经常无法采集到有效的数据,而且也很难反映出炸药在整个爆轰过程中爆速的变化。为了弥补目前炸药爆速测量的缺陷,提出一种爆速的连续测量技术,采用高速数据采集与连续电阻丝探针相结合的方法来测试水下爆炸、工程爆破、爆炸焊接等工况下的各种炸药爆速,爆轰行程每米测量点数为2.5万,测量范围从50 m/s到10 000 m/s,测量精度可以控制在小于1.0%,通过数学拟合算法和编制程序对测量数据信号进行图形可视化分析,并绘制出连续行程-爆速分析曲线,可以满足不同形式炸药爆速测量的试验研究。     

1.2 Measuring technique for partial hydrogen pressures in nitrogen-neon atmospheres

Gaseous impurities inside the discharge tube of a high pressure metal iodide lamp can have a large influence on the electrical and radiation properties of the lamp. Since the main gaseous impurity is hydrogen this gas must be eliminated from the discharge tube. One way of eliminating this gas is to use a hydrogen gettering material inside the outer bulb of the lamp since, under operational conditions hydrogen can diffuse through the quartz wall of the discharge tube into the outerr bulb.Because most types of high pressure metal iodide lamps have a mixture of a noble gas and nitrogen inside the outer bulb the gettering material must react only with the hydrogen and not with the nitrogen. For this reason the qetter has to be selective. In order to invistigate the selective gettering action of different chemical compounds a simple measuring technique was used to measure continuosly the hydrogen partial pressure inside the nitrogen-noble gas atmosphere.Most investigators use a mass-spectrometer or a gas chromatograph to register the change of the partial hydrogen pressure during the lifetime of the lamp. A much better technique is the use of a nickel diffusion leak combined with a manometer. A higher accuracy can be reached with this methods and it is possible to add or pump away thhe hydrogen without changig the nitrogen or noble gas atmosphere.The selective gettering action of a ZrAl alloys has been examined by this measuring technique and the results of this investigation are given.     

New Methods for Quality Analysis of Deep‐Drawn Packaging Components from Paperboard

Optimization of the quality of deep‐drawn cups requires methods for precise measuring of quality criteria. This paper presents new objective methods to describe the quality of deep‐drawn packaging components made of paperboard. The state of the art for quality analysis in three‐dimensional paperboard forming is presented. Methods for the analysis of visual quality using image analysis and for the analysis of shape accuracy using surface scans are developed. Experimental results are used for the verification of the methods and for the investigation of influences of main process parameters. The new methods are found to be both precise and objective. A large blankholder force has been shown to cause an increasing number of wrinkles and has a negative influence on the shape accuracy. A high die temperature also increases the number of wrinkles but enhances the shape accuracy. The punch temperature has no effect on the number of wrinkles, but high punch temperature has a significant and positive effect on the shape accuracy. Copyright © 2014 John Wiley & Sons, Ltd.     

飞机表面划痕非接触测量仪的研究

介绍了一种飞机表面划痕非接触测量仪。它以激光三角传感器为主要组成部件，并附以机械扫描装置，可完成被测飞机表面划痕的非接触测量。在分析了被测表面散、反射特性的基础上，给出了激光三角传感器正确放置方式，并提出改善测量精度的传感器姿态调整法。针对浅划痕测量时噪声较大的特点，提出利用子波分析的方法突出被测划痕形貌的信号处理方法，实验表明了此方法的可行性。本测量仪具有非接触测量、测量范围大、精度高、结构简单、成本较低的特点。     

组合热膜探头在气体流速测量中的应用

介绍了一种用于测量气体流速的组合热膜探头,并对组合热膜探头的温度特性以及温度补偿性能进行了实验研究.实验结果表明,组合热膜探头在微小流速测量中具有较高的灵敏度,可以弥补毕托管在低速情况下测量误差较大的缺陷,且具有较好的一致性。     

Experimental analysis on calibration of instrument broadening in a lidar system with Fabry–Perot etalon

A Brillouin lidar system based on a Fabry–Perot (F-P) etalon and intensified charge coupled device (ICCD) is widely used in measuring ocean physical properties. In previous signal detecting methods, the resolution of the obtained Brillouin spectrum is the major limitation on measurement accuracy of the Brillouin spectrum. The effect due to the instrument of the F-P etalon is relatively minor and typically neglected. However, because methods for obtaining a high resolution spectrum have greatly improved the spectral resolution, the instrument broadening has become the major error source and should be taken into consideration in the measurement. Instrument broadening is a common topic and has been widely researched. Unfortunately, for applications involving a high resolution spectrum, no detailed study has analyzed the performance of the methods for calibrating the broadening with high resolution experimental data. In this paper, the capability and the time costs of methods for reducing the broadening effect are evaluated for a high resolution spectrum obtained from underwater experiments. We also discuss in detail the implementation of the methods. Experimental results show that the three methods considered can effectively calibrate the broadening effect and improve the measurement accuracy from tens of MHz to MHz magnitude. Considering the similar performance of the methods, one method that is sufficient for online measurement is recommended as the optimal method.     

基于双光栅的平行度检测

为了对大型目标的平行度进行测量,设计并搭建了一套由双衍射光栅组成的平行度检测系统。采用两块衍射光栅正交组成光路,产生多条平行线作为基准线。通过照相机对参考线和待测目标进行拍照,对获得的图像进行处理,利用参考线的平行度偏差对目标所在平面的倾斜进行矫正,得到待测物的平行度测量结果。测量结果表明这种方法简单准确,满足测量精度高。     

Objective algorithms for the aerosol problem

Retrieval of the aerosol size distribution from optical measurements at ground level is well known to be a difficult problem. Nowadays objective techniques that can give a solution without the intervention of the researcher do not exist. We propose several objective methods that are well based in the mathematical and physical points of view. Their accuracy is evaluated and the top performance of the objective inversion techniques is presented. Moreover physical and experimental suggestions can be drawn to improve the accuracy. Inversions with experimental optical depths are also shown.     

Present problems in coordinate metrology for nano and micro scale measurements

From macro scale to nano scale measurements, the relationship between measuring range and measuring accuracy is a key parameter for measuring abilities. When measuring targets are three-dimensional (3D) and include complex geometrical features, high-accuracy cannot be achieved by conventional measuring methods. In this article, we discuss the limitations of 3D metrology in micro and nano scale profile measurements. For nano and micro scale measurements, we have to develop three key technologies as intelligent measuring methods, in-process measurements and high-accuracy standards.     

Measurement of the Optical Properties of Gold Colloids by Photoacoustic Spectroscopy

The particular features of gold have generated widespread interest for applications in different areas of science and technology. Notably, gold nanoparticles can be prepared with different sizes and forms and can be easily functionalized with a wide range of ligands. Developing effective experimental techniques to characterize such properties is thus important. In this work, photoacoustic spectroscopy was used to explore the relationship between the nanoparticle size and the optical absorption coefficient (at 405 nm and 532 nm) of gold colloid solutions, according to the Beer–Lambert’s law. A correlation between this optical parameter and the nanoparticle size was found. In addition, for comparison purposes, conventional UV–visible spectroscopy was used for measuring the absorbance at these two wavelengths. Very good agreement was obtained between the optical properties measured by the two methodologies at 405 nm. However, large discrepancies were obtained when measurements were performed at 532 nm. At the latter wavelength, the extent of radiation dispersion is too large for the Beer–Lambert’s law to be valid when the conventional spectroscopy technique is used. Unlike the UV–visible spectroscopy, the photoacoustic method is minimally affected by radiation dispersion effects. Thus, the photoacoustic method presents fewer limitations in that regard in characterizing the optical properties of metallic colloidal suspensions.     

Quartz thickness-shear mode pressure sensor design for enhanced sensitivity

Companies in the oil and gas industry rely upon acquisition of accurate downhole pressure data for management of reservoir resources. Pressure data must be acquired in extreme environments present in wells, including high pressures, high temperatures, and high levels of shock and vibration. A primary concern of oil and gas companies is that pressure transducers provide reliable data throughout the duration of well-testing jobs. Important performance parameters for well-test pressure gauges include inaccuracy arising from nonlinearity, hysteresis, nonrepeatability, and temperature. Accurate pressure measurements are required for determination of reservoir resources. Sensor output per unit pressure (sensitivity) and the corresponding minimum resolvable pressure (resolution) are important performance considerations. Pressure resolution is the key parameter for dynamic well-test analyses used to determine reservoir properties. Design limits, including maximum allowable pressure over the operating temperature range, also must be known. Pressure transducers must retain acceptable performance characteristics including accuracy, sensitivity, and resolution for long periods of operation to provide reliable data and reduce the frequency and cost of recalibration. This paper describes a unique quartz thickness-shear mode sensor that was developed for downhole pressure measurements. Pressure transducers that use this sensor meet the demanding requirements of downhole testing.     

Photothermal gas analyzer for simultaneous measurements of thermal diffusivity and thermal effusivity

In this paper, we describe a new, simple, and fast photothermal method for simultaneous measurements of two important gas thermal properties: thermal diffusivity and thermal effusivity. The method consists essentially in combining a photoacoustic cell and a thermal wave pyroelectric cell enclosed in a single compact gas analyzer. The photoacoustic cell is kept filled with synthetic air and sealed. The pyroelectric cell is also filled with synthetic air, and after some warm up time, the synthetic air is exchanged to the gas of interest. It is shown that the analysis of the transient and saturation signals of both photoacoustic and pyroelectric cells is capable of measuring the thermal properties with an accuracy of 3%. This particular capability of performing simultaneously the measurements of thermal diffusivity and thermal effusivity allows us to carry on the complete characterization of the thermal properties of gases.