Design of Accelerated Life Test Plans——Overview and Prospect

Accelerated life test(ALT) is currently the main method of assessing product reliability rapidly, and the design of efficient test plans is a critical step to ensure that ALTs can assess the product reliability accurately, quickly, and economically. With the promotion of the national strategy of civil-military integration, ALT will be widely used in the research and development(RD) of various types of products, and the ALT plan design theory will face further challenges. To aid engineers in selecting appropriate theories and to stimulate researchers to develop the theories required in engineering, with focus on the demands for theory research that arise from the implementation of ALT, this paper reviews and summarizes the development of ALT plan design theory. The development of the theory and method for planning optimal ALT for location-scale distribution, which is the most applied and mature theory of designing the optimal ALT plan, are described in detail. Taking this as the center of radiation, some problems that ALT now faces, such as the verification of the statistical model, limitation of sample size, solutions of resource limits, optimization of the test arrangement, and management of product complexity, are discussed, and the general ideas and methods of solving these problems are analyzed. Suggestions for selecting appropriate ALT plan design theories are proposed, and the urgent solved theory problems and opinions of their solutions are proposed. Based on the principle of convenience for engineers to select appropriate methods according to the problems found in practice, this paper reviews the development of optimal ALT plan design theory by taking the engineering problems arising from the ALT implementation as the main thread, provides guidelines on selecting appropriate theories for engineers, and proposes opinions about the urgent solved theory problems for researchers.     

Test Results of Key and Spherical Pivot Five-Shoe Tilt Pad Journal Bearings—Part II: Dynamic Measurements

Tests were conducted to measure the dynamic characteristics for two types of five-shoe tilt pad journal bearings having a load between pads configuration. Dynamic measurements of the two bearings are presented for 5000, 7000 and 12,000 rpm, and unit loads ranging from 126 kPa to 1724 kPa. Comparisons are made between the measured data and the theoretical prediction. Test data includes fluid film stiffness and damping, with calculated uncertainties and the measured radial stiffness of the pivots. The measured dynamic characteristics show the bearings differ with respect to stiffness and damping, while the measured radial pivot stiffnesses were nearly identical     

Test Analysis of Friction Couples With Solid Lubricant Coatings under Ground–Space Conditions and Prediction of Tribological Characteristics

As a result of an analysis of the literature data on ground–space tribological tests of friction couples with solid lubricant coating (SLC) ARSRI PP 212, the dependences for evaluating the starting antifriction characteristics have been determined. The wear life and coefficient of friction have been compared. According to results, calculation algorithms of tribological characteristics of friction couples with SLC for considered operational conditions have been developed and implemented.     

HORIBA Automotive Test Systems签署协议收购FuelCon AG

正2018年08月14日,HORIBA Europe GmbH宣布同意收购FuelC on AG(简称"FuelC on")的条件。FuelC on将成为发动机、传动系统、制动器和排放测试系统领域的领先供应商HORIBA Automotive Test Systems的一部分。交易的完成须经监管机构批准。     

美国理想工业公司推出全新Sure Test电路分析仪

2006年3月21日，应美国理想工业公司（IDEAL INDUSTRIES INC．）之约，笔者前往他们在北京东方广场的办公室。途经长安街，适逢中南海南墙新华门两侧玉兰花盛开．数百步之内，白花映着红墙黄瓦．间以松柏．真是清新高雅、庄严中透着和谐。     

基于LMS Test.lab的数控转台振动测试研究

基于LMS Test.lab测试系统,根据某成形铣齿机床的加工工艺特性和技术要求,提出与其相配套的数控转台(简称转台)振动测试方案,并进行实际加工工况下振动测试.测试表明,转台的固有频率远低于加工时的激振频率;铣齿过程中转台台面周向振动位移最大,且随着进给速度的增大而增大,随着消隙蜗杆作用力增大而减小.测试结论证明了该测试方案的可行性和有效性.     

基于LMS Test.lab的压缩机管道振动测试与分析

提出了应用LMS Test.lab进行往复压缩机管道振动测试的新方法,利用LMS Test.lab数据采集、分析软件及相关硬件,搭建了往复压缩机管道振动测试系统,对管道系统的固有频率进行了测试,并对测试结果进行了验证,从而证实了本系统的准确性与实用性.     

Correlation Study of Different Shear Stability Test Methods for Hydraulic Oils

Nowadays, different shear stability test methods for hydraulic oils are favored differently by different original equipment manufacturers (OEMs) or in different regions. Therefore, correlation studies between these test methods are becoming very important. In this articles, the correlations among three popular shear stability test methods for hydraulic oils were investigated. In addition, the relationship between these methods and the pump test was investigated. The results showed that the sonic shear test and bearing shear test showed a good correlation in terms of both viscosity loss and shear stability index (SSI). The viscosity change during the pump test can be reproduced both by sonic and bearing shear test methods and the relationship the between bearing shear test and pump test is almost consistent depending on different data sets.     

基于LMS Test．1ab的压缩机管道振动测试与分析

提出了应用LMS Test．1ab进行往复压缩机管道振动测试的新方法，利用LMS Test．1ab数据采集、分析软件及相关硬件，搭建了往复压缩机管道振动测试系统，对管道系统的固有频率进行了测试，并对测试结果进行了验证，从而证实了本系统的准确性与实用性。     

Gamma Test噪声估计的Kalman神经网络在动态工业过程建模中的应用

Kalman神经网络以其良好的自适应非线性逼近能力,被广泛用于复杂非线性动态工业过程建模。传统噪声估计方法难以得到观测噪声不确定动态工业过程的噪声估计值,因而常将观测噪声估计值置零以进行Kalman神经网络建模,影响Kalman神经网络的建模效果,限制了Kalman神经网络在观测噪声不确定动态工业过程建模中的应用。有效利用观测输入输出数据,提出样本有效噪声估计(Gamma test,GT)改进的Kalman神经网络建模方法。采用衰减记忆的GT对输入输出数据进行实时估计,得到准确的观测噪声估计值,再利用Kalman神经网络实现精确建模。验证结果表明,该方法对EKF神经网络模型和UKF神经网络模型均有很好的改善作用,有效解决观测噪声不确定引起的Kalman神经网络模型发散问题,为采用Kalman神经网络建立噪声不确定动态工业过程的精确模型提供了一条有效途径。     

Test of a Fluid-Film Wave Bearing at 350°C with Liquid Lubricants

A novel fluid-film wave bearing has been run at a higher temperature (350°C) than ever before with a perfluoropolyether (PFPE)-K liquid lubricant. Additionally, the wave journal bearing (45 mm diameter and 24 mm long) completed an 8-h endurance test at the NASA Glenn Research Center. The lubricant was PFPE-K XHT 500. After being maintained at 350° C for 8 h, the bearing temperature was raised to 356°C for the last 30 min of the run. The speed was 29,000 rpm and the load ranged from 2670 to 3560 N. The bearing was perfectly stable both dynamically and thermally. The observed temperature was more than 150°C above that run with current turbine engine lubricants. The use of high-temperature bearings as tested here would allow efficiency increases of more than 5% in aero or terrestrial turbine engines.     

基于LMS Test.Lab的电磁作动器振动测试与分析

作动器的动态特性对振动主动控制起着关键的影响作用。针对电磁作动器的频响特性进行研究,建立了典型线圈电磁作动器的力学模型,并通过LMS Test.Lab测试系统对两款性能不同的电磁作动器进行了频响测试和研究。     

Unbalance Response of a Super-Critical Rotor Supported by Foil Bearings—Comparison with Test Results©

This article compares theoretical and experimental results on the unbalance response of a super-critical rotor supported by two kinds of gas foil bearings. Analysis of the super-critical rotor is performed with viscoelastic foil bearings (VEFB) and conventional bump foil bearings and compared with early published experimental data. The vibration orbits obtained by theoretical investigation on the viscoelastic foil bearings (VEFB) and the conventional bump foil bearings are compared with the experimental vibration orbits of the super-critical rotor supported by both foil bearings. A numerical analysis program can calculate the static and dynamic characteristics of the elastically supported gas foil bearing using the measured stiffness and damping of the elastic foundation. After the stiffness and damping of both foil bearings are calculated using the perturbation method, vibration orbits of the flexible rotor modeled by the finite element method are calculated. Vibration orbits calculated by numerical analysis agree well with experimental data when the vibration amplitude is small and the rotating speed is below the bending critical speed. The numerical results also show that the enhanced structural damping of the elastic foundation reduces vibration near the bending critical speed.     

Rotordynamic Analysis of an Oil-Free Turbocharger Supported on Lobed Gas Foil Bearings—Predictions versus Test Data

This article presents the predictions of the rotordynamic performance of oil-free turbochargers (TCs) for various lobed gas foil bearings (GFBs) with the first-generation bump-type configuration and compares these predictions to the measured test data reported earlier. The three-lobed GFBs used for the simulations have increased bearing clearances and mechanical preloads with a fixed minimum bearing clearance, thus yielding larger average bearing clearances and higher wedge effects at the same time. The engine-induced TC housing excitation is found to have no influence on the critical speeds and damping ratios of the rotor rigid modes. The synchronous and asynchronous GFB analyses imply decreases in destabilizing forces for the highly lobed GFBs. The predicted critical speed and damping ratio of the TC rotor supported on the lobed GFBs demonstrate increasing system natural frequency and enhanced rotordynamic stability with increasing mechanical preload. The rotordynamic and bearing analyses of the lobed GFBs validate the beneficial effects of the mechanical preload on the rotordynamic stability of GFBs even with an increased average bearing clearance, which leads to a decreased bearing friction torque as well.     

Development of a Methodology to Predict Cylinder Liner Scuffing in the 6V92TA Engine Lubricant Test©

The requirements placed on lubricating oils at the top ring reversal point are becoming increasingly severe due to recent changes in engine technology, most of which are driven by emissions regulations. As a result, revised engine tests to evaluate cylinder liner scuffing are being introduced to engine oil specifications. Despite the high cost and generally poor repeatability of full-scale engine data, no laboratory screener test is commercially available. In the present study, various lubricant characteristics were correlated with the level of scuffing in the Detroit Diesel 6V92TA engine test. Good initial agreement was obtained with lubricant volatility measured at 525°C, which is predicted to be the approximate contact temperature under the most extreme conditions likely to exist during normal operation.

Measurement of lubricant volatility, however, yields no indication of additive response and also appears to become less accurate when applied to unconventional basestocks. As a result, a laboratory-scale wear test was developed to predict scuffing resistance under high stress conditions. The results of the wear and volatility rests are combined using a simple equation to form the Diesel Engine Oil Scuff Test (DEOST). The resulting methodology provides an R² correlation of 70 percent with scuffing measured in the 6V92TA engine and is sensitive to both basestock characteristics and antiwear additives. In addition, the DEOST results indicated that viscosity index improvers provide little benefit under high-temperature operation, an effect commonly observed by failure of petroleum-based multigrade oils in the 6V92TA engine test.     

The Engineering Professional and the Labor Market Demands： Electronic Engineer and Mechanical Engineer

The purpose of this study is to present results of a jobs classified survey from a newspaper in circulation in the city of Manaus （AM, Brazil）, between late 1990s and early 2000s. The structure and functionality of the CBO （Brazilian Occupational Classification） 2002, fundamental tool for data analysis was used, followed by collection, diagnosis and data analysis to identify the characteristics and transformations of the occupational tasks of the electronic and mechanical engineer. The analysis was based on CBO data in three distinct steps described in the methodology section, compared with a study conducted in the early 1990s, and finally, the overall prevailing trend required in professional engineering training in times of complexity and in the knowledge era was presented.     

Design and application of refrigerant recovery and filling control system based on MSP430

提出了一种应用于空调系统的多功能冷媒回收加注装置的控制方案。本方案硬件电路基于MSP430单片机设计,同时采用了高精度称重传感器和高性能放大器;软件设计采用中位值平均滤波算法。本装置不仅可以将冷媒废液净化后回收,而且可以定量加注新冷媒。同时,本装置具有施压、抽真空、加冷冻油等功能。实践证明,本控制系统成本较低、稳定性好,具有较高的实用价值。     

Fabrication and characterization of rugate structures composed of SiO_2 and Nb_2O_5

1Introduction Opticalcoatingdesignsbasedonlayers,whichareinhomogeneousalongthestackaxis,haveopticalandmechanicalpropertiesthatdiffer fromthoseofconventionalhigh low index stacks.Particularly,thewideaccessibleangular rangeandthelowopticalscatterlevelmake themsuperiortotraditionalstackswithrespect toselectedpurposessuchasomni directionalde vicesornotchfilters[14].Manufacturingsuch systemsinpracticerequiresthecalculation,dep osition,monitoringandcharacterizationofopti calcoatingswithawelldefinedc…     

Journal of Measurement Science and Instrumentation

Journal of Measurement Science and Instrumentation(CN14-1357/TH,ISSN 1674-8042)is published by North University of China.It is a comprehensive academic journal,aiming to present scientific research papers in the fields of measurement science and instrumentation,including general principles,technologies and instrumentation of measurement and control applied to such academic and industrial fields as mechanics,electric and electronic engineering,magnetics,optics,chemistry,biology,and so on.     

Journal of Measurement Science and Instrumentation

Journal of Measurement Science and Instrumentation(CN14-1357/TH,ISSN 1674-8042)is published by North University of China.It is a comprehensive academic journal,aiming to present scientific research papers in the fields of measurement science and instrumentation,including general principles,technologies and instrumentation of measurement and control applied to such academic and industrial fields as mechanics,electric and electronic engineering,magnetics,optics,chemistry,biology,and so on.