Internal Flow Field Measurement of Gas Turbine Based on Optical Flow Method

The in-cylinder flow field of the internal combustion engine is an important factor affecting the quality and combustion quality of the fuel mixture in the cylinder. In order to calculate the high-precision flow field, the paper presents a flow field calculation method based on the optical flow algorithm. The motion of the point was calculated using the change in pixel intensity within two temporally adjacent frame images. The results show the high accuracy and resolution of the flow field at small displacement conditions.

Simultaneous estimation of aerosol optical constants and size distribution from angular light-scattering measurement signals

The angular light-scattering measurement（ALSM） method combined with an improved artificial bee colony algorithm is introduced to determine aerosol optical constants and aerosol size distribution（ASD） simultaneously. Meanwhile, an optimized selection principle of the ALSM signals based on the sensitivity analysis and principle component analysis（PCA）is proposed to improve the accuracy of the retrieval results. The sensitivity analysis of the ALSM signals to the optical constants or characteristic parameters in the ASD is studied first to find the optimized selection region of measurement angles. Then, the PCA is adopted to select the optimized measurement angles within the optimized selection region obtained by sensitivity analysis. The investigation reveals that, compared with random selection measurement angles, the optimized selection measurement angles can provide more useful measurement information to ensure the retrieval accuracy. Finally,the aerosol optical constants and the ASDs are reconstructed simultaneously. The results show that the retrieval accuracy of refractive indices is better than that of absorption indices, while the characteristic parameters in ASDs have similar retrieval accuracy. Moreover, the retrieval accuracy in studying L-N distribution is a little better than that in studying Gamma distribution for the difference of corresponding correlation coefficient matrixes of the ALSM signals. All the results confirm that the proposed technique is an effective and reliable technique in estimating the aerosol optical constants and ASD simultaneously.

Methods Development for the Optical Determination of the Black Carbon Content of Loess Samples

We evaluate the applicability of an optical transmission measurement method commonly used for the analysis of the Black Carbon (BC) content of aerosol sample, to determine the BC content of loess sediments. A number of different sample pretreatment procedures are developed and compared, leading to an optimum preparation process. The results include: 1) Subtraction of the optical attenuation values before and after heating of the sample filters (“ΔATN”) varies linearly with the sample mass. The slope of the regression line provides the best determination of BC concentration. 2) When the sample mass is small, (NaPO3)6 pretreatment is best for BC measurement, and the BC concentration results are given by the slope of the regression between ΔATN and sample mass, for a series of samples of varying mass. 3) HF pretreatment accompanied by centrifugation and rinsing may produce a negative bias on the result. 4) Replicate measurements of BC for loess samples showed a maximum deviation less than 5.6%, suggesting that measurements of the BC concentration of a sequence of loess samples could determine variations to this degree of significance. 5) The overall trends of BC concentration in loess section sequences were similar for all chemical pretreatments. The BC concentration result for replicate samples is comparable when pretreated by the same procedure.

A New Method for Measurement of Local Solid Flux in Gas-Solid Two-phase Flow

Previous works have shown that the suction probe cannot be used to accurately measure the upward and downward particle fluxes independently. A new method using a single optical probe to measure the local solid flux is presented. The measurement of upward, downward and net solid fluxes was carried out in a cold model circulating fluidized bed (CFB) unit. The result shows that the profile of the net solid flux is in good agreement with the previous experimental data measured with a suction probe. The comparison between the average solid flux determined with the optical measuring system and the external solid flux was made, and the maximum deviationturned out to be 22%, with the average error being about 6.9%. These confirm that the optical fiber system can be successfully used to measure the upward, downward and net solid fluxes simultaneously by correctly processing the sampling signals obtained from the optical measuring system.

RESEARCH ON OPTICAL METHOD OF MONITORING PHOTOCATHODE PROCESS

The principle of an optical method of photocathode processing control, which is one ofphotocathode processing monitoring techniques, is discussed. A designed monitoring apparatus is describedand has been applied to investigate the optical parameters of multialkali photoemitter during the process offabrication. Some actual schemes using the method to monitor the preparation of photocathodεs are sug-gested.

Optically Powered Temperature Measuring Instrument for Big Rotor

Abstract: A micro - power consumption non - contact temperature measuring instrument for big rotor is introduced. As it solves very well the signal coupling under high speed rotation and power supply problem for probe, the instrument can realize persistent on - line temperature measurement for big rotor drived by the ordinary light transmitted by optical fiber under the room light.

Optical measuring systems and technologies for some urgent tasks in industry and science

Modern industry and science take novel optical measuring systems and laser technologies with high resolution and productivity for solving actual tasks,including safety problems for mining,oil,atomic and railway in-dustries.The TDI SIE's results in these trends are presented.

Utilization of Extrinsic Fabry-Perot Interferometers with Spectral Interferometric Interrogation for Microdisplacement Measurement

The paper presents a number of signal processing approaches for the spectral interferometric interrogation of extrinsic Fabry-Perot interferometers(EFPIs). The analysis of attainable microdisplacement resolution is performed and the analytical equations describing the dependence of resolution on parameters of the interrogation setup are derived. The efficiency of the proposed signal processing approaches and the validity of analytical derivations are supported by experiments. The proposed approaches allow the interrogation of up to four multiplexed sensors with attained resolution between 30 pm and 80 pm, up to three times improvement of microdisplacement resolution of a single sensor by means of using the reference interferometer and noisecompensating approach, and ability to register signals with frequencies up to 1 kHz in the case of 1 Hz spectrum acquisition rate. The proposed approaches can be used for various applications, including biomedical, industrial inspection, and others, amongst the microdisplacement measurement.

Electro-optical sampling non-synchronous delay scanning measurement of electron beam bunch length at BFEL

The Electro-optical sampling delay scanning technique can be used for electron beam bunch length measurement. A novel non-synchronous delay scanning technique based on the electro-optical sampling measurements is presented. Based on Beijing Free Electron Laser （BFEL）, the electron beam bunch length was measured with the electro-optical sampling technique for the first time in China. The result shows that the electron beam bunch length at BFEL is about 5.6±1.2 ps.

Retrieval of aerosol optical constants from angular light-scattering measurement signals using principal component analysis approach

An angular light-scattering measurement (ALSM) method combined with the probability density function-bmsed ant colony optimization algorithm (PDF-ACO) is proposed for retrieval of aerosol optical constants. An optimal measurement angle selection method using a principal component analysis (PCA) approach is developed to improve retrieval accuracy. Results indicate that optimized angle selection can ensure retrieval accuracy. The aerosol optical constants over Beijing, China, which are available from the Aerosol Robotic Network (AERONET), are then rec on structed. The ALSM method's con vergence properties are also studied via comparison w让h those of the light reflection-transmittance measurement (LRTM) method. Results retrieved using the ALSM method show better convergence speed and accuracy than those retrieved using the LRTM method because the ALSM method does not require solution of the radiative transfer equation and allows more useful signals to be obtained. Additionally, the inverse accuracy of the refractive index results is better than that of the absorption index results;this is attributed to differences between the monodromic characteristics of the refractive index and absorption index retrieval results. All results confirm that the combination of the ALSM method w让h the PDF-ACO algorithm and the optimal measurement angle selection method provides effective and reliable aerosol optical constant reconstructio n.

Absolute surface form measurement of flat optics based on oblique incidence method

In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the absolute surface shape of the test flat. By adding two sets of measurements, the absolute surface error of the interferometer＇s reference flat can be obtained. The new method can not only calibrate the reference flat error of interferometer, but also provide the absolute measurement method for high precision optical components applied in high power laser systems.

Predefined Exponential Basis Set for Half-Bounded Multi Domain Spectral Method

A non-orthogonal predefined exponential basis set is used to handle half-bounded domains in multi domain spectral method (MDSM). This approach works extremely well for real-valued semi-infinite differential problems. It spans simultaneously wide range of exponential decay rates with multi scaling and does not suffer from zero crossing. These two conditions are necessary for many physical problems. For comparison, the method is used to solve different problems and compared with analytical and published results. The comparison exhibits the strengths and accuracy of the presented basis set.

基于物理信息神经网络的金属表面吸收率测量方法

漫反射金属吸收率的准确测量十分重要且比较困难.量热法可靠性较高,但是参数反演较为困难.为此,建立了一种物理信息神经网络方法.该方法通过神经网络拟合温度上升段曲线,进而获得吸收率.为了验证该方法,开展了数值仿真和实验研究.数值仿真结果表明,该方法适用于吸收率测量,抗干扰能力强,反演精度高,在0.05—0.2的吸收率范围内,最大误差为0.00092.实验以喷砂镀金铝板为被测对象,受表面粗糙度、镀金工艺等影响,这些样品的吸收率处于2%—10%之间,测量重复精度优于1%.基于物理信息神经网络的吸收率测量方法有望成为一种有力的金属表面吸收率测量方法.

大量程高线性光谱共焦位移测量系统

兼具高精度、高稳定性并能实现非接触测量的光谱共焦位移测量系统在工业、医疗、科研等许多领域得到了广泛应用。目前制约光谱共焦位移测量系统应用发展的因素是大量程和高线性度。讨论了光谱共焦位移测量系统中色散物镜实现线性轴向色散的条件,设计了一种高线性色散和大色散范围的色散物镜,指定了适合的公差范围,加工装配了一组色散物镜,搭建了光谱共焦位移测量系统,采用双频激光干涉仪进行了位移标定,并对标准量块进行了厚度测量。结果表明,该系统工作波段为450 nm~650 nm,实际位移范围为10 200μm,线性拟合判定系数R^(2)达到0.993 7,实际测量最大误差仅为3μm,证明该光谱共焦位移测量系统同时具备大量程、高线性度和高测量精度的特点。

非均衡性测量法在一次性使用静脉采血针不良事件报告风险信号挖掘与分析中的应用

目的及时识别一次性使用静脉采血针风险,发挥医疗器械不良事件监测体系的实时监测效能。方法采用非均衡性测量法中的报告比值比(Reporting Odds Ratio,ROR)法和比例报告比(Proportional Reporting Ratio,PRR)法对广东省医疗机构上报的234例一次性使用静脉采血针不良事件的真实世界报告进行风险信号挖掘,调查、分析事件发生原因。结果监测发现,不同持有人的一次性使用静脉采血针有关连接组件松脱不良事件报告数量与占比存在失衡,符合风险信号判定标准。经分析研究,该风险信号得到确认,发生原因主要为产品原因,含说明书不完善、生产工艺问题、设计缺陷。结论非均衡性测量法中的ROR法和PRR法可有效挖掘和识别不同持有人的一次性使用静脉采血针不良事件风险,在有源、无源和体外诊断试剂类医疗器械不良事件风险信号的挖掘、识别、分析应用方面具有一定参考和推广价值。

复杂曲面光学元件高精度面形检测技术概述

复杂曲面光学元件应用于光学系统中可以增大系统设计自由度,同时减少系统所需元件数量,有利于实现光学系统的紧凑化、轻量化,被誉为现代光学系统的变革性元件,被广泛应用于空间光学、光刻系统、汽车照明等领域,极大推动了航天、国防及高科技民用事业的发展。然而,复杂曲面光学元件对面形精度要求较高,如何对其面形进行高精度检测从而指导加工成为限制该类元件大范围应用的瓶颈。文章对10余种常用的复杂曲面光学元件面形检测方法进行了分类梳理,按照是否采用干涉原理,将检测方法分为非干涉检测法和干涉检测法两大类,分别介绍了各种检测方法的原理和适用范围,回顾了各方法的发展历程,着重分析了几种典型方法进行面形检测的特点,并对未来复杂曲面光学元件高精度面形检测技术的发展趋势加以展望。

基于服装个性化智能定制的三维人体测量系统物-像结构算法的研究

目前,我国基于服装个性化智能量身定制的理念日趋完善。但是,在消费者目标尺寸自动获取方面仍然缺乏实用的设备和技术,成为了大多数企业个性化智能定制发展的一个瓶颈,其根本原因是缺少实用性强的个性化智能定制系统。人体动态测量与其他工业产品精密测量相比具有自身独有的特殊性和困难。在探讨了现有的光学类基于个性化智能定制系统的现状的前提下,针对目前存在的激光三维人体扫描测量系统普遍存在硬件设备庞大、结构复杂的问题,对文中提出的基于个性化智能定制系统进行了原理设计,建立了系统的物-像结构算法的数学模型。该算法采用了扫描单元旋转的测量方式,使系统能够在垂直方向上获得较大的测量范围,目的是使系统采用较小的硬件获取满意的三维人体空间坐标,有利于节省竖直空间、减小体积。该算法已成功应用于基于服装个性化智能定制系统。为了验证本算法的精度,设计了与法国力克系统的三维人台对比扫描实验,实验数据验证了本系统结构算法的精度、工程实用性和可靠性。

基于光学法的水下爆炸冲击波流场压强测量与分析

针对水下爆炸流场多参数测量,发展了基于OpenCV图像处理技术的光学法,对水下爆炸实验中冲击波超压进行测量并与理论和数值结果作对比。发现基于OpenCV图像处理技术的光学法能够较好地实现冲击波阵面的捕获与超压测量并实现冲击波传播过程、爆轰产物发展等流场信息的获取,可为光学法在水下爆炸实验中的应用提供借鉴参考。

明渠非标准断面法测流水位流量关系的率定及影响因素分析

为探究明渠非标准断面法测流的水位流量关系曲线的率定问题,以新疆第三师某团场25处渠道量水断面为研究对象,利用FlowTracker 2手持式声学多普勒流速仪进行了水位流量关系率定工作.根据实测结果,率定了各渠道量水断面的水位流量关系曲线,并对所率定出的曲线进行了符号检验、适线检验和偏离数值检验及误差分析,在此基础上,对流量拟合参数的影响因素进行了分析.结果表明:所率定的25处渠道量水断面中,14处具有稳定的水位流量关系,5处受回水影响、6处受渠道淤积影响为不稳定的水位流量关系;在渠道粗糙系数Ra、边坡系数m及坡降i相同的条件下,流量拟合参数与渠道底宽b总体上呈正相关;在渠道粗糙系数Ra、边坡系数m及底宽b相同的条件下,流量拟合参数与渠道坡降i总体上呈负相关.研究结果可以为灌区自动化量水设备测流准确性的校核提供参考依据.

基于时空图像法监测流量的测量误差分析

流量测量是开展水文分析和水资源管理的必要任务,有助于了解河流的水量变化,预测洪水风险,优化水资源分配。传统接触式测流方法装置布设复杂、测量效率低,以视频测流为代表的非接触式方法极大地提高施测效率,降低了成本,但对测流结果的误差分析不足,导致测流结果在水文分析与水资源管理中的应用存在风险。为分析视频测流误差,在通过视频图像法计算断面水位、时空图像法(Space-time Image Velocity,STIV)计算断面流速的基础上,假定单次测量的误差分布,推求了水位和流速测量误差、流量测算误差及其主要来源。并定义了误差平均带宽(EAB)来定量评估误差的大小。以栾川县养子沟流域为对象开展实例研究,结果表明:在水位或流速快速上升阶段,测量误差区间较小;仅考虑水位的不确定性、仅考虑流速的不确定性,以及同时考虑水位和流速的不确定性时流量测量误差平均带宽(EAB)值分别为4.98%、10.83%和15.83%,流速测量不确定性对流量的影响比水位测量不确定性对流量的影响更大。考虑水位与流速不确定性影响的视频测流方法有利于提高流量测量准确性,为流域水资源管理提供可靠的数据支撑,特别是在需要对不断变化的水体状况进行监测和响应的情况下。对误差的深入理解也有助于改进视频测流技术,以减小误差并提高其在实际应用中的可靠性。