用“函数缝”方法设计多程控接口监控程序模块

通过介绍、分析和比较数字存储示波器中RS232、局域网(LocalAreaNetwork,LAN)、通用接口总线(GeneralPurposeInterfaceBus,GPIB)、多接口程控的各种实现方法,着重论述和提出了一种结构清晰、易于扩展的实现多接口程控的编程方法——“函数缝”方法,给出了VisualC++开发环境下该方法的实现过程,并设计了相关接口动态链接库(DynamicLinkLibraries,DLL)。结果表明,“函数缝”方法便于新程控接口的扩展,同时简化了程序结构。

高斯光束通过含失调窄缝光阑的失调光学系统的传输特性

利用硬边窄缝光阑的近似展开式和适用于失调光学系统的广义衍射公式，得出了高斯光束经含失调窄缝光阑的失调光学系统传输的近似解析式。模拟结果表明输出光束场分布与光束参量、光阑尺寸、AB—CD矩阵元、光阑失调量和光学系统失调量有关。针对给定的光学系统和高斯光束定量分析了各失调量对输出光束场分布的影响．结果表明：光阑横向位移、光学系统横向位移和角位移均引起垂直于z轴截面内明显的光强非轴对称分布。当光阑半宽度为1mm时，光阑的衍射作用使腰斑半径为0．5mm的高斯光束产生-1．586π～1．465π范围的相对相移，且光阑横向位移、光学系统横向位移和角位移均引起焦平面前后相对相移的迅速变化。随光阑宽度变小，各失调量对输出光束特性的影响越明显。

带钢与轧辊间弹性压扁分布函数

根据工作辊、支撑辊挠度与轧辊间弹性压扁的变形协调条件,建立并求解了带钢与轧辊间弹性压扁应力分布函数方程,在实际应用中表明,计算精度较高,与实测结果吻合较好。

A new kind of wavelet-based method for spectrum deconvolution

To subtract the slit function from the measured spectrum, a wavelet-based deconvolution method is proposed to obtain a regularized solution of the problem. The method includes reconstructing the signal from the wavelet modulus maxima. For the purpose of maxima selection, the spatially selective noise filtration technique was used to distinguish modulus maxima produced by signal from the one created by noise. To test the method, sodium spectrum measured at a wide slit was deconvolved. He-Ne spectrum measured at the corresponding slit width was used as slit function. Sodium measured at a narrow slit was used as the reference spectrum. The deconvolutton result shows that this method can enhance the resolution of the degraded spectrum greatly.

Simulation of three-dimensional tension-induced cracks based on cracking potential function-incorporated extended finite element method

In the finite element method,the numerical simulation of three-dimensional crack propagation is relatively rare,and it is often realized by commercial programs.In addition to the geometric complexity,the determination of the cracking direction constitutes a great challenge.In most cases,the local stress state provides the fundamental criterion to judge the presence of cracks and the direction of crack propagation.However,in the case of three-dimensional analysis,the coordination relationship between grid elements due to occurrence of cracks becomes a difficult problem for this method.In this paper,based on the extended finite element method,the stress-related function field is introduced into the calculation domain,and then the boundary value problem of the function is solved.Subsequently,the envelope surface of all propagation directions can be obtained at one time.At last,the possible surface can be selected as the direction of crack development.Based on the aforementioned procedure,such method greatly reduces the programming complexity of tracking the crack propagation.As a suitable method for simulating tension-induced failure,it can simulate multiple cracks simultaneously.

A dynamic problem on the edges of a mode Ι crack subjected to moving unit-step loads

By the theory of complex functions, a dynamic problem on the edges of a mode I crack subjected to moving unit-step loads are investigated. The Riemann-Hilbert problem is easily formulated by the ways of self-similar functions. The analytical solution obtained is rather simple and concise. After the solution was utilized by superposition theorem, the relevant solution on the case of arbitrary loading can be obtained.

CVC板形控制技术的研究

对板形的控制实际上是对辊缝形状的控制,CVC轧机采用反对称形状的工作辊轴向移动使轧辊的凸度连续可调,从而使辊缝的凸度可调。通过确定CVC工作辊辊型曲线,建立CVC板形控制模型,在生产应用中具有诸多优点。

Fatigue Crack Initiation Sizing Using Acoustic Emission

One of the major concerns in structures is early detection of a growing crack to prevent fracture, predict remaining useful life, schedule maintenance and reduce costly downtimes. AE （acoustic emission） is a non-destructive testing method with potential applications for locating and monitoring fatigue cracks. This paper focuses on in-situ monitoring of structural health, specifically detection of small crack growth and crack initiation in structures using AE technology. A probabilistic AE-based model for small fatigue cracks was developed and the uncertainties of the model were estimated. The paper discusses the methodology used, experimental approach, results obtained and predictive models developed.The developed model can be used to evaluate the integrity of structures and assess structural health by estimating the probability density function of the length of detected cracks. The outcome of this research has significant potential to be used for in-situ monitoring and evaluation of structural integrity.

Quantum twisted double-slits experiments:confirming wavefunctions'physical reality

Are quantum states real? This most fundamental question in quantum mechanics has not yet been satisfactorily resolved, although its realistic interpretation seems to have been rejected by various delayedchoice experiments. Here, to address this long-standing issue, we present a quantum twisted double-slit experiment. By exploiting the subluminal feature of twisted photons, the real nature of a photon during its time in flight is revealed for the first time. We found that photons' arrival times were inconsistent with the states obtained in measurements but agreed with the states during propagation. Our results demonstrate that wavefunctions describe the realistic existence and evolution of quantum entities rather than a pure mathematical abstraction providing a probability list of measurement outcomes. This finding clarifies the long-held misunderstanding of the role of wavefunctions and their collapse in the evolution of quantum entities.

A new procedure for investigating three-dimensional stress fields in a thin plate with a through-the-thickness crack

In the paper, a new procedure is proposed to investigate three-dimensional fracture problems of a thin elastic plate with a long through-the-thickness crack under remote uniform tensile loading. The new procedure includes a new analytical method and high accurate finite element simulations. In the part of theoretical analysis, three-dimensional Maxwell stress functions are employed in order to derive three-dimensional crack tip fields. Based on the theoretical analysis, an equation which can describe the relationship among the three-dimensional J-integral J(z), the stress intensity factor K(z) and the tri-axial stress constraint level Tz(z) is derived first. In the part of finite element simulations, a fine mesh including 153360 elements is constructed to compute the stress field near the crack front, J(z) and Tz(z). Numerical results show that in the plane very close to the free surface, the K field solution is still valid for in-plane stresses. Comparison with the numerical results shows that the analytical results are valid.

An experimental investigation on the mechanism of fluid flow through single rough fracture of rock

The structure of fractures in nature rock appears irregular and induces complicated seepage flow behavior.The mechanism and quantitative description of fluid flow through rock fractures is a difficult subject that has been greatly concerned in the fields of geotechnical,mining,geological,and petroleum engineering.In order to probe the mechanism of fluid flow and the effects of rough structures,we conducted a few laboratory tests of fluid flow through single rough fractures,in which the Weierstrass-Mandelbrot fractal function and PMMA material were employed to produce the fracture models with various fractal roughnesses.A high-speed video camera was employed to record the fluid flow through the entire single rough fracture with a constant hydraulic pressure.The properties of fluid flow varying with the fracture roughness and the influences of the rough structure were analyzed.The components of flow resistance of a single rough fracture were discussed.A fractal model was proposed to relate the fluid resistance to the fracture roughness.A fractal equivalent permeability coefficient of a single rough fracture was formulated.This study aims to provide an experimental basis and reference for better understanding and quantitatively relating the fluid flow properties to the structures of rock fractures.