Optoelectronic Method of Noncontacting Reconstruction of the Profile of a Surface of Three Dimensional Objects of Large Dimensions

An optoelectronic method is considered for noncontacting reconstruction of the surface profile of three-dimensional objects of large dimensions. The optimal conditions for performing measurements are identified. It is shown that the proposed method, in contrast to the already known methods, does not require fine tuning of the equipment. A numerical method is given for compensating distortions caused by aberrations. A method is described for reconstructing the surface profile cell by cell which increases the accuracy of measurements.     

Analysis of Photothermal Characterization of Layered Materials – Design of Optimal Experiments

In this paper numerical calculations are presented for the steady-periodic temperature in layered materials and functionally-graded materials to simulate photothermal methods for the measurement of thermal properties. No laboratory experiments were performed. The temperature is found from a new Green's function formulation which is particularly well-suited to machine calculation. The simulation method is verified by comparison with literature data for a layered material. The method is applied to a class of two-component functionally-graded materials, and results for temperature and sensitivity coefficients are presented. An optimality criterion, based on the sensitivity coefficients, is used for choosing what experimental conditions will be needed for photothermal measurements to determine the spatial distribution of thermal properties. This method for optimal experiment design is completely general and may be applied to any photothermal technique and to any material with spatial variation of thermal properties.     

水平仪检定器准确度性能的探讨

水平仪检定器是用于校准钳工水平仪、框式水平仪分度值误差的主要计量标准器具,水平仪检定器的准确度直接影响水平仪的量值溯源质量。通过分析水平仪检定器工作原理,指出了示值误差是表征水平仪检定器准确度性能的指标,提出了水平仪检定器示值误差数学模型,分析了水平仪检定器示值误差的测量关键。     

Use of diagnostic system for assessment of lifetime of power plant components

The material of some parts of energetic machines may be exposed to increased temperatures. Creep and its combination with fatigue is one aspect of material degradation. This aspect is included in diagnostic system DIALIFE. The system is designed for two levels of evaluation of a residual lifetime. The first OFF-LINE level is determined for use by experts from authorised companies. The second ON-LINE level is determined for the continuous evaluation of the material damage. Results of this diagnostic system can be utilised for the controlled ageing and lifetime extension of power plant components.     

Solutions of some problems of vibration of inhomogeneous bodies

The object of the paper is to solve the problems of vibrations of thick elastic cylindrical and spherical shells when only Young's modulus E varies from point to point on the region according to certain rules. Here Cinelli's method is applied for obtaining the solutions in general form. The general rules for variation of E for which the above method is applicable, is expressed.     

The development of a velocity risk map of Taiwan for seismic resistant design of buildings

Abstract

A seismic risk analysis procedure previously developed for ground acceleration calculations of Taiwan is extended for ground velocity determination. The procedure is particularly suitable for Taiwan and other areas, where only limited information on seismicity is available. A velocity attenuation formula is established and used for risk calculation. This attenuation is consistent with an acceleration attenuation law of Taiwan. The resulting velocity risk map can be used in conjunction with an acceleration risk map produced before to serve as a basis for elastic design response spectrum construction. A risk level is chosen for building design. This level corresponds to a probability of ten percent for the design earthquake motion parameters being exceeded in a time span of fifty years. A form of elastic design spectrum and an equivalent lateral force coefficient are suggested as an application of the risk maps developed.     

Practical prediction of creep and shrinkage of high strength concrete

Model for practical prediction of creep and shrinkage of normal strength concrete, developed previously, is extended to high strength concrete. It is found that only a minor adjustment for the concrete strength effect is needed in the formulas for drying creep. The formulas for basic creep and shrinkage need no adjustment. The prediction model is compared with test data for creep and shrinkage obtained recently by Ngab, Nilson and Slate, and by Collepardi, Corradi and Valente, and a satisfactory agreement is demonstrated. The coefficient of variation of the deviations from test data is not larger than that for the normal cient of variation of the deviations from test data is not larger than that for the normal strength range. However, the existing data are rather limited and further testing is desirable.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Determination of the Constitutive Constants of Non-Linear Viscoelastic Materials

A simple method for computing the strain and the time dependent constants for non-linear viscoelastic materials is presented. The method is based on the finite time increment formulation of the convolution integral, and is applicable for materials which exhibit separable strain and time variables. The strain-dependent function can take any form including the hyperelastic potentials such as the Mooney-Rivlin strain energy function. The time-dependent function is based on the Prony series. The attraction of the method is that true material constants can be computed for any deformation history.     

Calculation of the critical current density of hard superconductors from the magnetization of cylindrical samples

A new approximation formula for the critical current density is presented which is more exact than those proposed previously and allows the evaluation of the current density in the range of the initial magnetization curve. The relative error is calculated for one practical case and is plotted for the different branches of the magnetization curve.     

On suitable formulations of the method of modal analysis for numerical calculations

The method of modal analysis is a method widely used in structural analysis of linear systems. After a short introduction two step by step formulations for modal calculations are discussed. One of them is of more theoretical interest, the other is recommended for practical calculations for multi-degree-of-freedom systems because it is efficient in computing time. The first is formulated for the whole system the latter for each mode. Likewise a combination of the method of modal analysis and the LAPLACE transformation is established. The numerical calculation of the LAPLACE transformation is done by using the algorithm of the Fast FOURIER transformation. The advantages of the different formulations for numerical calculations are discussed.     

基于能耗的热量表耐久性 试验经济性分析

针对热量表耐久性试验中的能耗问题,基于理论计算的方法对耐久性试验装置运行时能耗进行了分析,给出了串联不同批次数量热量表时,耐久性试验装置的耗能及其对应每一批次热量表的均耗能量,比较了串联批次数量不同时每一批次耗能量的大小;同时,分析了水源保温在热量表耐久性试验中的能耗问题.结果表明,影响热量表耐久性试验经济性的主要因素...     

A study of the effectiveness of Electronic Stability Control in Canada

Electronic Stability Control (ESC) is a crash avoidance system found on many vehicles. Unlike air bags, which only help during a collision, ESC helps to avoid a loss of control that could lead to a collision by preventing skidding. ESC is designed to help the driver stay in control of the vehicle during an emergency manoeuvre, such as when the driver needs to swerve to avoid an obstacle.Our study is an effectiveness evaluation of ESC using crash data. The purpose of a Canadian evaluation study is to examine whether there is an issue with multi-vehicle crashes, and whether ESC is effective in Canadian weather conditions, i.e. on ice, snow and slush.Our results show that ESC is effective for all ESC-sensitive crashes (41.1% effectiveness) and its effectiveness is higher for ESC-sensitive injury crashes only (54.8% effectiveness). In particular, ESC is effective in the case of all multi-vehicle ESC-sensitive crashes (23.2% effectiveness) and of multi-vehicle ESC-sensitive injury crashes (28.4% effectiveness). ESC is also effective for single-vehicle ESC-sensitive crashes, both for all severities of crashes (18.6% effectiveness) and injury crashes only (49.3% effectiveness).The results of the study also show that ESC is effective in Canadian weather conditions (i.e. on ice, snow and slush). The effectiveness of ESC on roads covered with ice, snow and slush is 51.1% for ESC-sensitive crashes of all severities and 71.1% for ESC-sensitive injury crashes. ESC is also effective on dry roads (36.3% effectiveness for ESC-sensitive crashes of all severities and 46.6% effectiveness for ESC-sensitive injury crashes), wet roads (35.8% effectiveness for ESC-sensitive crashes of all severities and 49.5% effectiveness for ESC-sensitive injury crashes) and for both cars (28.5% effectiveness for ESC-sensitive crashes of all severities and 43.7% effectiveness for ESC-sensitive injury crashes) and LTVs (51.9% effectiveness for ESC-sensitive crashes of all severities and 69.6% effectiveness for ESC-sensitive injury crashes).     

The Effects of Inspector Error on The Operation of a c-Chart

A model for inspector performance is developed which allows for the possibility that some defects are not observed. It is assumed that the number of defects per inspection unit is Poisson and each defect is missed with probability 1-p. The resulting distribution of observed defects is found to be Poisson with a different parameter. The implications of this model for the operation of a c-chart are discussed. It is shown that when more than one inspector is used, the operating characteristic curve for the chart will be flatter than under error-free inspection.     

Influence of the type of cathode on the dynamic characteristics of ionization waves

The influence of different types of cathodes on the dynamic characteristics of ionization waves is determined experimentally. It is established that when the discharge is initiated by negative pulses, the maximum wave propagation velocity is observed for a cold cathode while the maximum peaking of the output pulse leading edge is observed for a heated cathode. The mechanism for this effect is discussed. Pis’ma Zh. Tekh. Fiz. 24, 39–42 (July 12, 1998)     

印刷制版原理的剖析

总结了照相凹版、阳图PS版、阴图PS版、丝网印刷版、无水平印版、银盐扩散版等印版的制版原理,并分析归纳出得到的印版是凹版还是凸版的规律.利于同学们理解制版的原理,根据负片类型和感光胶类型就可以迅速分析出应该得到凹版或凸版,特别适合于化学基础较差、对感光胶分解和固化机理了解甚少的学生学习印刷制版原理.     

Probabilistic Assessment of UPV Test Result of a Degasser Unit

The novelty of this paper is to address a fundamental characteristic of ultrasonic pulse velocity (UPV) test result called distribution pattern and development of a methodology to simplify non-normal distribution patterns of UPV into normal distribution domain for easy applicability of quality assurance criteria for practicing engineers. In this paper probabilistic assessment methodology of UPV test results collected from a de-gasser structure of a refinery in India is discussed. Detailed analysis is performed to identify the distribution characteristics of UPV. No conventional distribution type including normal distribution fitted for UPV test results. A further attempt is made to derive simplified normal distributions with two different modes from the empirical cumulative distribution function of in situ test results. This creates scope for application of existing normal distribution based quality assurance criteria to non-normal domain of UPV. Criteria of characteristic strength instead of mean value is proposed as a better parameter for estimation of the quality of the material. Detailed physical interpretation and justification for the methodology is discussed with mathematical reasoning. The method is discussed in reference to existing literature. It is shown that the method is applicable to derive quality assurance criteria where simple assumption of normal distribution is not valid for UPV. Thus the method has the potential to make UPV a more useful test based on statistical reasoning for application on full scale structures.     

夏季热湿地区新风冷负荷特点及新风湿负荷的处理

以广州为例,分析了热湿地区空调建筑物新风负荷的特点,得出在整个夏季新风冷负荷中潜冷负荷占87.9%,由此可见用于夏季新风除湿的能耗远远超过用于新风降温的能耗.对常见的三种除湿方式用于夏季空调新风除湿方案进行了综合分析,认为液体干燥剂除湿系统最适合用于热湿地区夏季新风湿负荷的处理.     

压力表检定中数据判读及测试问题的解决

分析讨论了压力表检定中数据的设定、读取及判定,给出了压力表示值误差是否超出允许误差的快速判定方法,对压力表检定过程中耐压测试和压力表指针偏转平稳性测试中的问题进行了讨论。     

Estimation of the effects of countermeasures on different types of accidents in the presence of regression effects

In an earlier paper [Danielsson, 1986], we studied the problem of estimating the safety effect of a countermeasure on the expected number of accidents at road junctions when high-accident sites are selected for the study. Often, however, the countermeasure leads to varying effectiveness on different types of accidents. This paper is a generalization in that we estimate effects of countermeasures for each type of accident. A major result, for which empirical support is provided, is that the expected regression effect is the same for all types of accidents.