Compensation of timing jitter-induced distortion of sampledwaveforms

The presence of timing jitter between the trigger signal and the sampling strobe in an equivalent-time sampling oscilloscope causes distortion of the recorded waveform. Two methods exist to estimate the waveform from the jittered measurements. One method, called the median method, is based on the calculation of the point-by-point median of a large set of waveform measurements. It is shown here that this method is asymptotically biased if noise is present and if the waveform is nonmonotonic. Another method, called the pdf deconvolution method, is based on an estimation of the jitter probability density function and on a technique to deconvolve this density function from the average of all recorded waveforms. To estimate the jitter probability density function, it is assumed that the waveform has a part which can very well be approximated by a ramp during a time span which is smaller than the standard deviation. It is shown that a significant asymptotic bias is introduced by the method when this assumption is violated. A novel approach is proposed, based on a parametric model of the jitter probability density function, which results in an asymptotic unbiased estimate of the jitter probability density function. The method is experimentally verified, and it is explained why this method is especially useful when one is interested in the Fourier spectrum of the recorded waveform     

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.     

太平洋牡蛎(Crassostrea gigas)鳃氯细胞的超微形态研究

利用透射电子显微镜研究了太平洋牡蛎鳃氯细胞的超微结构。氯细胞主要分布于鳃小叶的基部,呈口袋状,细胞个体较大,在鳃表面有一凹隐的分泌腔。细胞中,细胞核多位于基部,体积较小;具有发达的微细小管系统,但小管的分支程度低;线粒体数量较少且结构不够发达;可见少量的高尔基体,未见内质网。鳃氯细胞是太平洋牡蛎鳃渗透压调节的重要细胞系统。     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Measurements of the thermal magnetoresistance of aluminum

The transverse thermal magnetoresistance of single-crystal plates of pure aluminum has been measured at liquid helium temperatures. It is shown that the high field Lorentz ratio is practically independent of field in agreement with theoretical predictions, and the value of the Lorentz ratio in high fields is discussed in terms of thermal and electrical relaxation times. It is also shown that the previously observed linear increase of the electrical resistivity in high fields is reflected in the thermal resistivity, and the origin of this effect is discussed. It is believed that the linear behavior is not caused by a magnetic breakdown effect in this case, but is due to other intrinsic or nonintrinsic effects.     

装甲材料侵彻试验仿真

采用显式动力学算法对装甲材料侵彻试验的过程进行数值仿真研究。介绍了冲击动力学的基本理论，对侵彻试验中装甲材料的破坏进行了数值模拟，校核了试验靶架的强度，仿真结果和试验值进行了比较。研究结果表明。装甲材料侵彻试验过程的数值仿真是有效可行的。与侵彻试验相比，数值仿真具有可重复性好、周期短、成本低的优点，对物理试验具有重要指导意义。     

Formulation of non-standard dissipative behavior of geomaterials

In this paper, fundamental mathematical concepts for modeling the dissipative behavior of geomaterials are recalled. These concepts are illustrated on two basic models and applied to derive a new form of the evolution law of the modified Cam-clay model. The aim is to discuss the mathematical structure of the constitutive relationships and its consequences on the structural level. It is recalled that non-differentiable potentials provide an appropriate means of modeling rate-independent behavior. The Cam-clay model is revisited and a standard version is presented. It is seen that this standard version is non-dissipative, which at the same time explains why a non-standard version is needed. The partial normality is exploited and an implicit variational formulation of the modified Cam-clay model is derived. As a result, the solution of boundary-value problems can be replaced by seeking stationary points of a functional.An erratum to this article can be found at .     

汽车电子部件振动疲劳试验规范设计

本文根据汽车电子部件加速度振动试验要求 ,设计了与实际载荷作用等价的正弦激振载荷幅度与试验时间的关系 ,制定了一套完整的加速振动试验方案并完成了相关实验 ,得到了强化系数K ;对直接采用道路谱信号应用于UD振动台上的试验进行了设计。整个振动试验设计可指导汽车电子产品试验规范工作 ,具有实际意义和应用价值。     

具多件内装物的瓦楞纸箱尺寸优化设计

跳出传统的设计思路，提出装多件内装物的瓦楞纸箱尺寸优化设计方法，建立优化设计模型，编写程序用于生产，节省纸用量，降低成本。     

Formulation of non-standard dissipative behavior of geomaterials

In this paper, fundamental mathematical concepts for modeling the dissipative behavior of geomaterials are recalled. These concepts are illustrated on two basic models and applied to derive a new form of the evolution law of the modified Cam-clay model. The aim is to discuss the mathematical structure of the constitutive relationships and its consequences on the structural level. It is recalled that non-differentiable potentials provide an appropriate means of modeling rate-independent behavior. The Cam-clay model is revisited and a standard version is presented. It is seen that this standard version is non-dissipative, which at the same time explains why a non-standard version is needed. The partial normality is exploited and an implicit variational formulation of the modified Cam-clay model is derived. As a result, the solution of boundary-value problems can be replaced by seeking stationary points of a functional.     

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.     

Dissipative heating under conditions of shear flow of liquid in a flat channel of finite length in view of temperature dependence of viscosity

A steady-state process of heat transfer is considered under conditions of Couette-type shear flow in a flat channel of finite length. The problem is solved in view of dissipation of mechanical energy and of temperature dependence of viscosity under symmetric boundary conditions of the third kind on the channel walls. A number of simplifying assumptions are made, and approximate solutions are obtained within two formulations of the initial problem. In the first case, the constant velocity of the moving channel wall is assigned. This problem is conventional and leads to quite predictable results. In the second case, it is assumed that it is the resultant force applied to the moving channel wall which is assigned. The wall velocity in the steady-state mode is not known in advance. It is found that, in this case, the dependence of kinematic and thermal characteristics of the process on Froude number exhibits a hysteretic pattern.     

液氧贮槽增压管线冻堵故障分析

由于没有将液氧贮槽升压后再向槽车充装液氧,在充装过程中使贮槽内形成负压,导致外界空气被倒吸入放空管线,长期积累使增压管线结冰冻堵。通过吹扫增压管线排除了故障。为防止同类故障再次发生,改进了向槽车充装液氧的操作规程。     

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)     

声音定向传输中的失真分析

对声音定向传输中的失真问题进行分析和实验。从理论上分析了声音在空气中传播时声源信号的幅值与谐波失真的关系;实验验证说明了这一失真现象及其数值关系;提出了利用预处理方法减小失真的解决方案。     

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.     

克伦特罗残留检测免疫芯片的研制

为实现克伦特罗残留的规模检测设计其残留检测的免疫芯片。以玻片为载体并对玻片表面进行APTES-DGA化学修饰,将克伦特罗抗体偶联至玻片表面, 以牛血清白蛋白封闭玻片表面活性基团,加待测品和标样,标样中辣根过氧化酶标记的克伦特罗和待测品中的克伦特罗与克伦特罗抗体竞争性结合,借助辣根过氧化酶催化化学发光反应并检测光信号值,检测过程中考查加样体积、温育温度、温育时间、洗液浓度及化学发光积分时间等对检测结果的影响,检测方法学试验中考查检出限、定量限、线性和回收率等指标。结果显示：通过APTES-DGA修饰载玻片具有较好的信号均一性和抗体偶联能力,检测过程中加样体积为50 μL、温育温度为37 ℃、温育时间为30 min、洗液浓度为10倍稀释液、化学发光积分时间为60 s具有较稳定的检测结果。本法研制的免疫芯片检测克伦特罗残留快速、简单、准确。     

Effect of orientation of the substrate on the conditions of growth of HgTe films by molecular beam epitaxy

The kinetics of growth of HgTe films under conditions of molecular beam epitaxy on the (310)- and (100)-oriented CdTe buffer layers is studied by ellipsometry. It is established that the minimum pressure of Hg vapors required for growth of HgTe films on the (310) surface is four times lower than the pressure required for growth on the (100) surface. It is found that, during the growth of HgTe films, no Te adsorption layer is formed on the (310) surface, whereas a Te adsorption layer is actually formed on the (100) surface. The equivalent thickness of this layer is 1 Å.     

鲍鱼壳珍珠层无机文石片的层状微结构研究

贝壳珍珠层是软体动物壳的最内层,经过若干世纪的自然进化,贝壳珍珠层形成了优良的微结构,并使贝壳具有了相当高的强度、刚度及断裂韧性.本文利用扫描电镜(SEM)观察了鲍鱼贝壳珍珠层的主要微结构特征,发现其是由层状的无机文石片和有机胶原蛋白质组成的生物陶瓷复合材料.根据发现的贝壳珍珠层层状微结构特征,建立贝壳珍珠层三维有限元模型,并用此模型分析了珍珠层的拉伸屈服极限与无机文石片拉伸屈服极限及其厚度的关系,研究表明珍珠层的屈服极限随无机文石片屈服极限的增加和无机文石片厚度的减小而增加.