A solution method for static and dynamic analysis of three-dimensional contact problems with friction

A solution method is presented for the analysis of contact between two (or more) three-dimensional bodies. The surfaces of the contacting bodies are discretized using quadrilateral surface segments. A Lagrange multiplier technique is employed to impose that, in the contact area, the surface displacements of the contacting bodies are compatible with each other. Distributed contact tractions over the surface segments are calculated from the externally applied forces, inertia forces and internal element stresses. Using the segment tractions, Coulomb's law of friction is enforced in a global sense over each surface segment. The time integration of dynamic response is performed using the Newmark method with parameters and . Using these parameters the energy and momentum balance criteria for the contacting bodies are satisfied accurately when a reasonably small time step is used.

The applicability of the algorithm is illustrated by selected sample numerical solutions to static and dynamic contact problems.     

厚壁圆筒在热、磁耦合场作用下的动态响应

运用力学和电磁场的知识对厚壁圆筒结构建立平衡方程,并通过 Laplace 和 Hankel 积分变换对物理方程进行变换,得到一个可解的方程形式.提出一种解析方法求解在热磁冲击作用下厚壁圆筒的动应力和磁场矢量扰动,得到柱体内动应力响应历程和分布规律及磁场矢量扰动的响应历程和分布规律.实例计算表明该方法是简单、有效的,并给出了一些有实际意义的结果.     

Vibration analysis of axially moving magnetic tape with comparisons to static and dynamic experimental results

The demand for greater storage capacity is prompting the development of data storage tape with greater volumetric and areal density. As the data tracks on these tapes become narrower, minimization of the lateral tape motion (LTM) becomes more important to prevent loss of data due to read/write errors. In order to identify and minimize sources of LTM, a vibration model is developed which simplifies the tape drive to a fixed-fixed Euler-Bernoulli beam model with axial velocity. The effects of varying axial velocity, tension, free span length, and tape thickness were investigated. The calculated natural frequencies are compared to those obtained by both static and dynamic experiments. Effects of varying the length, tape thickness, and tension were studied in the static experiment while the effects of changing speed and tension were studied in the dynamic experiment.     

Numerical solution of static and dynamic equations of cables

The mechanical equations of an extensible, perfectly flexible curvilinear material (cable) are formulated. The static problem can be solved either by a minimization technique or by an iterative finite difference method which also permits dealing with forces that are not derived from a potential. In the dynamic alternative the solution of the equations is obtained from finite difference discretization explicit in time - this can apply to different kinds of constitutive laws and to different kinds of boundary conditions. Application of these numerical methods to electric transmission lines subject to electromagnetic forces shows a good agreement between computation and experimental data.     

基于带电直导线周围磁场的磁传感器动静态特性标定方法

目前磁传感器多用于对静态或准静态磁场环境的测试,当被测磁场矢量快速变化时,磁传感器的动态特性成为影响其测量精度的关键因素。针对测试现场环境中难于产生标准的高频交变激励磁场源致使磁传感器动态特性无法准确快速标定的难题,提出一种基于带电直导线周围磁场的磁传感器动静态特性现场快速标定方法。首先提出并构建了一种基于带电直导线的标准宽频带磁场发生器,采用毕奥-萨伐尔定律分析了带电直导线周围磁场分布规律;其次通过在长直导线中加载典型交变激励电流,产生典型交变磁场,采用系统辨识方法实现对磁传感器动态特性标定;最后对某矢量磁传感器测量系统进行了时域、频域动态模型标定。实验表明所提出的磁传感器动态模型标定方法具有简便、快速、高效、准确的优点,便于工业现场对各类磁传感器进行动静态特性标定。     

Binding-time analysis for both static and dynamic expressions

This paper presents a specializer and a binding-time analyzer for a functional language where expressions are allowed to be used as both static and dynamic. With both static and dynamic expressions, data structures can be statically accessed while they are residualized at the same time. Previously, such data structures were treated as completely dynamic, which prevented their components from being accessed statically. The technique presented in this paper effectively allows data structures to be lifted which was prohibited in the conventional partial evaluators. The binding-time analysis is formalized as a type system and the solution is obtained by solving constraints generated by the type system. We prove the correctness of the constraint solving algorithm and show that the algorithm runs efficiently in almost linear time. Kenichi Asai, Ph.D.: He is a research associate at the Department of Computer Science, Faculty of Science, the University of Tokyo. He obtained his bachelors degree, masters degree, and doctor of Science from the University of Tokyo in 1990, 1992, and 1997, respectively. His research interests are in Programming Languages in general, in Partial Evaluation and Reflection in particular. He is a member of ACM, IPSJ, and JSSST.     

Numerical solution of static and dynamic nonlinear multi-degree-of-freedom systems

The performance of a dynamic algorithm is demonstrated on a series of nonlinear multi-degree-of-freedom systems. Nonlinear dynamics, large deflections and postbuckling behaviour are dealt with. In highly nonlinear problems of a prevailing static nature it is shown that, due to its clear physical interpretation, the dynamic approach allows easier guessing of initial conditions assuring convergence.     

Classification of malware based on integrated static and dynamic features

Collection of dynamic information requires that malware be executed in a controlled environment; the malware unpacks itself as a preliminary to the execution process. On the other hand, while execution of malware is not needed in order to collect static information, the file must first be unpacked manually. None-the-less, if a file has been executed, it is possible to use both static and dynamic information in designing a single classification method.In this paper, we present the first classification method integrating static and dynamic features into a single test. Our approach improves on previous results based on individual features and reduces by half the time needed to test such features separately.Robustness to changes in malware development is tested by comparing results on two sets of malware, the first collected between 2003 and 2007, and the second collected between 2009 and 2010. When classifying the older set as compared to the entire data set, our integrated test demonstrates significantly more robustness than previous methods by losing just 2.7% in accuracy as opposed to a drop of 7%. We conclude that to achieve acceptable accuracy in classifying the latest malware, some older malware should be included in the set of data.     

A numerical method for the solution of static and dynamic three-dimensional elasticity problems

Kupradze's functional equation, reduced to a regular Fredholm integral equation of the first kind, was solved by applying a new numerical method, based on numerical integration, whose collocation points are chosen in self-similar surfaces. An application of the method to a particular problem of elasticity demonstrated a sufficient accuracy and stability of the method. It was shown that the proposed method is faster, simpler and more easily programmable than the existing classical methods. Finally, suggestions were made for a better use of the method and for possible improvements.     

AspectC++: An integrated approach for static and dynamic adaptation of system software

Modern computer systems require an enormous amount of flexibility. This is especially the case in low-level system software, from embedded devices to networking services. From literature and practice, various approaches to modularize and integrate adaptations have been investigated. However, most of this work is implemented with dynamic languages that offer extensive run-time support and enable easy integration of such approaches. System software is written in languages like C or C++ in order to minimize utilization of system resources and maximize efficiency. While for these languages highly optimized and reliable compilers are available, the support for static and dynamic adaptation is rather limited. In order to overcome these limitations, we present an adaptation approach that is based on a sophisticated combination of static and dynamic aspect weaving for aspects written in AspectC++. This facilitates the incremental evolution and deployment of system software that has to be “always on”. We demonstrate the feasibility of our approach and its applicability to two pieces of system software, namely the Squid web proxy and the eCos operating system, which is used in the domain of resource-constrained deeply embedded systems.     

Fesap—design program for static and dynamic structural analysis

The Structural Analysis Program, SAP, has been widely accepted and modified to perform a wide variety of structural analyses at many universities, government and industrial organizations. This paper will document the development of SAP into a user-oriented program for linear dynamic and static analysis of large complex structures which is referred to as FESAP (Finite Element Structural Analysis Program). The paper will also describe companion computer programs which constitute a total design system for thermo-structural analysis. The total system includes mesh generation programs, a heat transfer program, the structural analysis program, batch and interactive graphic computer programs, and post-processors for the results of the heat transfer and structural analysis programs.     

Wave dispersion characteristics of orthotropic double-nanoplate-system subjected to a longitudinal magnetic field

Microsystem Technologies - This article deals with the wave propagation problem of nanosize double-layered plates while subjected to a longitudinal magnetic field. To achieve more reliable answers,...     

Cobra: a light-weight tool for static and dynamic program analysis

Static source code analysis tools have become indispensable for the development of reliable software applications. The best analyzers can reveal subtle flaws in a code base, but they can also be slow. In part this is due to the collection of detailed information about the possible data and control flow of an application to support the broadest possible range of analyses. For larger code bases it is not unusual that even the best of breed static analyzers can take an hour or more to complete an analysis. In this paper we describe a framework for a much faster, but more light-weight type of static analysis that can support interactive use for standard types of queries. The Cobra tool we designed for this purpose can scale to explore millions of lines of code interactively. The tool is mostly language agnostic, and can therefore easily be configured to resolve even dynamic program analysis queries.     

Development of user-friendly programs for static and dynamic analysis of radial impellers

Radial backward straight-bladed (BSB) impellers and backward curved bladed (BCB) impellers are analysed using the concept of cyclic symmetry. Impellers with single cover plate and two cover plates are considered. Both static and dynamic analyses are done and user-friendly programs for design of these impellers are developed.     

Large displacement extension of consistent shell element for static and dynamic analysis

The superior performance of the consistent shell element in the small deflection range has encouraged the authors to extend the formulation to large displacement static and dynamic analyses. The nonlinear extension is based on a total Lagrangian approach. A detailed derivation of the non-linear extension is based on a total Lagrangian approach. A detailed derivation of the non-linear stiffness matrix and the unbalanced load vector for the consistent shell element is presented in this study. Meanwhile, a simplified method for coding the nonlinear formulation is provided by relating the components for the nonlinear B-matrices to those of the linear B-matrix. The consistent mass matrix for the shell element is also derived and then incorporated with the stiffness matrix to perform large displacement dynamic and free vibration analyses of shell structures. Newmark's method is used for time integration and the Newton-Raphson method is employed for iterating within each increment until equilibrium is achieved. Numerical testing of the nonlinear model through static and dynamic analyses of different plate and shell problems indicates excellent performance of the consistent shell element in the nonlinear range.     

一种新型在线式铁谱仪的静磁场设计与应用

以在线式全流量扫描铁谱仪为背景,对静磁场的磁路进行设计,并从磁荷模型出发,引入广义二项式定理将不可积因子转变为可积因子,从而对该磁场的磁感应强度进行解析计算,通过对比理论值和实际测量值发现解析表达式很好地反映了静磁场的磁感应强度分布规律.在此基础上,将所设计的静磁场应用到某新型涡喷航空发动机性能监测中,对监测到的磨粒进行了分析,监测结果与发动机的实际情况相符合.     

Algorithms for Web service selection with static and dynamic requirements

A main feature of Service Oriented Architectures is the capability to support the development of new applications through the composition of existing Web services that are offered by different service providers. The runtime selection of which providers may better satisfy the end-user requirements in terms of quality of service remains an open issue in the context of Web services. The selection of the service providers has to satisfy requirements of different nature: requirements may refer to static qualities of the service providers, which do not change over time or change slowly compared to the service invocation time (for example related to provider reputation), and to dynamic qualities, which may change on a per-invocation basis (typically related to performance, such as the response time). The main contribution of this paper is to propose a family of novel runtime algorithms that select service providers on the basis of requirements involving both static and dynamic qualities, as in a typical Web scenario. We implement the proposed algorithms in a prototype and compare them with the solutions commonly used in service selection, which consider all the service provider qualities as static for the scope of the selection process. Our experiments show that a static management of quality requirements is viable only in the unrealistic case where workload remains stable over time, but it leads to very poor performance in variable environments. On the other hand, the combined management of static and dynamic quality requirements allows us to achieve better user-perceived performance over a wide range of scenarios, with the response time of the proposed algorithms that is reduced up to a 50 % with respect to that of static algorithms.     

A comparison of static,dynamic, and hybrid analysis for malware detection

In this research, we compare malware detection techniques based on static, dynamic, and hybrid analysis. Specifically, we train Hidden Markov Models (HMMs) on both static and dynamic feature sets and compare the resulting detection rates over a substantial number of malware families. We also consider hybrid cases, where dynamic analysis is used in the training phase, with static techniques used in the detection phase, and vice versa. In our experiments, a fully dynamic approach generally yields the best detection rates. We discuss the implications of this research for malware detection based on hybrid techniques.