A more rational approach to the problem of an elastoplastic thick-walled cylinder

A new incremental theory has been developed for solving the problem of partially yielded thick-walled cylinders. Incremental stresses and strains are directly used as variables, hence numerical differentiation in the evaluation of stresses and strains is not required. The stresses and strains in all principal directions can be computed at the same time from governing equations for each increment of loading. Since the consideration of loading history is involved, the present theory is particularly suitable for predicting stress and strain distribution of a thick-walled cylinder subjected to nonproportionate loading.     

Local Effects of a Concentrated Load Applied to Orthotropic Beams

An analytical solution for the bending, shearing and normal stresses of infinitely long orthotropic beams subjected to a concentrated load is presented. Numerical values are obtained for three-layered plywood and pine wood.     

Time-optimal Control Systems with Norm Constraints on State Variables at Intermediate Times

The problem of time-optimal control systems with both norm constraints on control inputs and on state variables at discrete intermediate times is formulated as an L-problem in the theory of moments. The simplex method is used for solving a nonlinear minimizing problem inherent in the functional analysis solution to this latter problem. Numerical results are presented for a train operation.     

Agency problem, institutions, and technology policy: Explaining Taiwan's semiconductor industry development

Taiwan has made significant progress in the semiconductor industry with government agencies and bureaucrats as the driving forces over the past 30 years. Taiwan's impressive achievement in the semiconductor industry clearly indicates that the government failures and agency problem usually associated with deep government involvement did not occur in Taiwan. Why is that the case? This paper proposes a principal-agent framework for technology policy and applies the framework to discuss the institutional arrangements through which bureaucrats were controlled effectively in executing the semiconductor industry policies in Taiwan. By analyzing the institutional and organizational arrangements Taiwanese leaders made to mitigate the agency problem, this paper brings bureaucrats into the popular developmental state theory and emphasizes that the success of state intervention should not be taken for granted, and it also brings politics into technology policy analysis and stresses the importance and complexity of agency problem in technology policy.     

Partially plastic thick-walled tubes

A theory is presented for the partial plastic yielding of thick-walled cylindrical tubes acted upon by any combination of internal pressure, external pressure and end load when the material follows an arbitrary stress-strain law. The solution combines (a) the distortion energy theory of plastic flow and (b) the effects of elastic compressibility of the plastic material.Numerical values for stresses and strains are given for certain special cases of internal pressure in thick-walled open-ended tubes for an idealized stress-strain law, and the results are compared with earlier approximate theories.     

Interaction Between Two Internal Collinear Cracks and a Circular Inclusion Under Longitudinal Shear

This paper deals with the evaluation of the stress field in a plate with two unequal and collinear anti-plane shear cracks and a circular inclusion. The solution for the stress state is obtained in a series-form solution. A concrete example is given of a plate with two equal cracks and a circular inclusion subjected to anti-plane shear at infinity. The problem may describe the state of stress on an equatorial section of unidirectional fiber composite when cracks appear in meridional x sections between fibers.     

The solution of boundary value problems by multiple Laplace transformations

By use of the multiple Laplace transform a partial differential equation and its associated boundary conditions characterizing a boundary value problem in n independent real variables can be transferred directly into an algebraic equation in n independent complex variables. This algebraic equation can be solved for the multiple transform of the solution of the boundary value problem. Multiple inversion of this transform then gives the desired solution. The general theory underlying such solution of boundary value problems in two and three independent variables is advanced in detail. Use of this theory is illustrated by solution of two specific problems.     

Torsion of a Laminar Composite Debonded Over a Penny-shaped Area

The effect of an imperfectly bonded laminar composite is examined in terms of the intensification of the torsional stresses operative near the imperfection which is assumed to be a circular shaped area. The laminar composite is modelled by four layers of different materials with the two outer layers being infinite in height and debonding occurs at the interface of the two inner layers. The analysis based on the application of Hankel transforms and the solution of a pair of dual integral equations can be easily extended to a multilayered system. Depending on the size of the layer thickness relative to the radius of the debonded area, delamination may take place either in a stable or unstable fashion. The analytical results also indicate that the influence of lamination tends to lower the stress intensity around an interface imperfection as compared to the stress state in a homogeneous solid containing the same imperfection. Numerical results are obtained for two special laminate geometries and discussed with reference to the pertinent parameters used in the current theory of fracture mechanics.     

Unified Finite Integral Transform Analysis

A special matrix is introduced, the elements of which are zero or first-order operators. This matrix is used to define the initial boundary value problem which covers a wide class of engineering applications. To bring the solution of the problem within the realm of integral transform theory, a new finite integral transform and the corresponding inversion formula are developed. The necessary orthogonality relations is derived using an extension of the Gauss-Green theorem. The formal solution obtained here can be applied to study heat conduction problems, elasticity problems, etc.     

On Incremental Deformations of Initially Stressed Media with Couple Stresses

A two-dimensional theory for the incremental deformations of an initially stressed continuum with couple stresses is established in this paper. As applications of theory, the problems of internal instability and wave propagation are studied. It is found that the otherwise non-dispersive waves become dispersive, and additional local modes of buckling and vibratory motion are observed. To complete the theory, a stress function formulation of equations is also presented.     

基于TRIZ解决中小企业提高科技项目申报能力研究

近年来,科技项目作为政府支持初创期中小企业发展的有效手段,使得很多企业因此受益。而初创期企业由于自身条件所限,申报科技项目的水平和能力明显不足,提高企业申报科技项目的能力,是很多初创期企业的需求,但靠自身能力无法实现。基于TRIZ理论体系,综合利用系统功能分析、资源分析、物场分析等方法分析问题产生的原因,提出原理解并结合实际讨论求得可行方案,在此基础上提出对策建议。     

On A Class of Describing Functions for Dyadic Systems

This paper presents a theory of Sal Input Describing Function (SIDF) for the characterisation and analysis of a class of nonlinear dyadic systems. The SIDFs are determined for single input as well as dual input dyadic elements. The theory is applied to evaluate output response of a closed loop system subjected to sal input functions.     

冷杉属植物叶角质层内表面的观察及其系统学意义

 在扫描电镜下,比较观察了冷杉属全世界36种2变种的叶角质层内表面的结构特征,根据叶角 质层内表面胞间凸缘特征的显著差异,将冷杉属植物归为4类:(1)直且发达的单凸缘;(2)双凸缘; (3)不发达的单凸缘;(4)弯曲且发达的单凸缘。并发现这四种凸缘类型在冷杉属中的分布格局与该 类植物的地理分布具有相关性。根据所观察的结果和前人的属下分类系统以及化石资料,认为北美西部是现代冷杉属植物的一个多样性中心。     

基于上升敲出期权的基础设施项目政府担保价值研究

基于基础设施项目政府担保的期权特性辨析,指出带有担保上限的基础设施项目政府担保是一种上升敲出看跌期权,在B-S期权定价模型的基础上,结合特定约束条件提出了政府担保价值的定价模型及其计算公式。     

Text categorization via generalized discriminant analysis

Text categorization is an important research area and has been receiving much attention due to the growth of the on-line information and of Internet. Automated text categorization is generally cast as a multi-class classification problem. Much of previous work focused on binary document classification problems. Support vector machines (SVMs) excel in binary classification, but the elegant theory behind large-margin hyperplane cannot be easily extended to multi-class text classification. In addition, the training time and scaling are also important concerns. On the other hand, other techniques naturally extensible to handle multi-class classification are generally not as accurate as SVM. This paper presents a simple and efficient solution to multi-class text categorization. Classification problems are first formulated as optimization via discriminant analysis. Text categorization is then cast as the problem of finding coordinate transformations that reflects the inherent similarity from the data. While most of the previous approaches decompose a multi-class classification problem into multiple independent binary classification tasks, the proposed approach enables direct multi-class classification. By using generalized singular value decomposition (GSVD), a coordinate transformation that reflects the inherent class structure indicated by the generalized singular values is identified. Extensive experiments demonstrate the efficiency and effectiveness of the proposed approach.     

On synthesizing team target controls under obstacles and collision avoidance

This paper deals with the problem of target control synthesis under obstacles for a group of systems subjected to conditions of collision avoidance. They also satisfy a team property of being obliged to lie within a given moving convex reference set of restricted volume that may be reconfigured to avoid the obstacles and is directed towards the target set. The specification of the desired on-line team feedback control strategies then relies on calculating related backward reachability sets, which is achieved through duality methods of nonlinear analysis. An optimization problem for team target control is finally solved.     

A floquet theory of the linear synchronous machine

The differential equation describing the three-phase linear synchronous machine containing an arbitrary stator MMF distribution is reformulated and solved as a perturbation theory problem. The solution algorithm presented also produces a transformation capable of reducing to constant coefficient form the differential equation describing the machine. The theory is illustrated by applying it to a simple two pole machine.     

Nonlinear thermo-inertial stability of thin circular FGM plates

In this research, linear and non-linear stability behaviour of a thin circular FGM plate subjected to the uniform temperature rise and the constant angular velocity loadings is analyzed. Properties of the FGM media are distributed across the thickness based on a power law form. Each property of the metal or ceramic constituents is considered to be the function of temperature based on the Touloukian model. General equilibrium equations for such conditions are obtained based on the classical plate theory. At first, the non-linear governing equations are established in a complete asymmetrical form. After that, two different analytical methods are presented to study the bifurcation behaviour. Existence of bifurcation phenomenon is examined. Pre-buckling analysis is performed for a plate with the immovable clamped edge. Stability equations are obtained based on the adjacent equilibrium criterion. The resulted equations are solved via the two distinct methodologies, i.e. the exact solution in terms of Coulomb wave functions and the power series method. A non-linear solution is also presented to detect the equilibrium path of the heated rotating FGM plate. It is found that the angular speed may stabilize the homogeneous circular plate which buckles during uniform heating. Furthermore, snapping may occur for FGM plates under the simultaneous action of heating and uniform rotation.     

情报学理论发展动力观的构想

情报学理论内在的矛盾和冲突,既是情报学学科生死存亡的转换枢纽,又是其发展动力的生发带。情报学体系化与问题化的冲突、情报学理论与情报实践的紧张、情报学化与非情报学化的危机这三对矛盾与情报学发展紧密缠结在一起,情报学理论发展的每个转向都与它们相关。情报学不同发展阶段对这些矛盾的解决方式、解决程度生动展示着这个时代情报学理论的主导精神和成熟水平。     

政府研发投入对中国大学技术转移合同的影响——基于三螺旋理论的视角

三螺旋理论强调政府、企业和大学的协同演化和互动,受到了世界各国政府、企业和大学的高度重视,政府在企业—大学互动中的作用更是三螺旋理论讨论的热点问题。从三螺旋理论的视角,以我国大学2003—2010年的省级面板数据为依据,通过实证分析,研究了政府研发投入对大学技术转移合同的影响。研究发现,各省市大学获得的政府科技经费投入非常显著地促进了该省市大学技术转移合同数量和收入两方面的增长;并且,国家科技支撑计划、863计划、国家自然科学基金项目和973计划的数量也是大学技术转移合同数量/收入的促进因素。