Special-purpose Program Research Articles

Stability of continuous welded rail track

As the use of continuous welded rail (CWR) increases in track structures, derailing disasters associated with track buckling also increase in great numbers due to high compressive thermal stress. A three-dimensional CWR track model is developed in the present study to be used for extensive buckling analysis of CWR tracks subjected to temperature load. The analysis model is encoded into a special purpose program using the finite element method. The CWR track model consists of four elements: a mono-symmetric thin-walled open section beam element with 7 degrees of freedom per node to represent the rail; a solid beam-on-elastic-foundation element having 6 degrees of freedom per node to simulate the tie, including vertical and/or longitudinal ballast resistance; an elastic spring element with two nodes and zero length to stand for pad-fastener system; and spring elements for the lateral or longitudinal ballast resistances. Also, two types of significant nonlinearity are included in the track model: the geometric nonlinearity of the rail element, and the materially nonlinear resistance of the ballast. The validity of the present study is strictly verified through a series of comparative analyses with those by others. The nonlinear analysis results have shown that buckling of the track is a three-dimensional problem, and the 2-D rail–tie model and beam model overestimated the CWR track stability.

Introducing QoS awareness in distributed programming: QTcl

AbstractA number of distributed applications require communication services with quality of service (QoS) guarantees. Building global‐scale distributed systems with predictable properties is one of the great challenges for computer systems engineering in the new century. Work undertaken within the Internet Engineering Task Force has led to the definition of novel architectural models for the Internet with QoS support. According to these models, the network has to be appropriately configured in order to provide applications with the required performance guarantees.In next‐generation networks, enabling applications to interact with the underlying QoS services is of primary importance. Hence, several special‐purpose application programming interfaces (APIs) have been defined to let applications negotiate QoS parameters across QoS‐capable networks. However, so far, none of these APIs are available in different operating environments. We believe that such features should be embedded in programming environments for distributed applications. In this work we present how we included QoS control features in Tcl, a programming language that has been widely adopted for the development of distributed multimedia applications. Our work has led to the implementation of QTcl, an extended Tcl interpreter that provides programmers with a new set of primitives, in full compliance with the standard SCRAPI programming interface for the RSVP protocol. QTcl in highly portable, in that it enables standard QoS negotiation to be performed in a seamless fashion on the most common operating systems. Copyright © 2003 John Wiley & Sons, Ltd.

Three-dimensional modelling of the vertical–horizontal rolling process

This paper discusses the utilisation of the slightly compressible finite element formulation to the numerical analysis of the vertical–horizontal rolling process. The first part of the paper details the basis of the plasticity theory for slightly compressible materials and presents an overview of its numerical implementation. Of particular interest in vertical–horizontal rolling are topics related to the prediction of the dog-bone shape when using a Eulerian formulation, the treatment of the frictional boundary conditions along the three-dimensional roll–workpiece contact interfaces and the modelling of the material streamlines within the plastically deforming region. The second part of the paper presents a comparison between theoretical predictions obtained by means of a special purpose computer program developed under the proposed approach and experimental results taken from the literature. Assessment is made in terms of the cross-sectional shapes, roll separating force and torque.

On the Results of the Work of the Arbitrazh Courts in 2001 and the Tasks for Carrying out Judicial Reform and the Federation Special-Purpose Program for Development of the Judicial System of Russia in 2002–2006

On the Results of the Work of the Arbitrazh Courts in 2001 and the Tasks for Carrying out Judicial Reform and the Federation Special-Purpose Program for Development of the Judicial System of Russia in 2002–2006

Optimizing selection of acoustical measurement equipment to meet educational needs

As part of their learning experience, students of acoustics need to know and understand measurement techniques, particularly those involving sound pressure levels, sound intensities, spectrum analyses, and signal generation. It is important to realize that students not only should obtain hands-on experience, but also gain a keen appreciation for significant factors affecting accuracy and long-term stability of the equipment being chosen for use. The requisite equipment may not be inexpensive but some economies can be effected by judicious selection of devices without seriously compromising the validity of experimental results. For example, Type 2 microphones, rather than Type 1, may suffice to yield revealing trends in measurements of ‘‘real life’’ situations; and due consideration must be given to the ruggedness of equipment with respect to storage conditions and environmental exposure during use. Fundamental experiments include measurements of SPL, spectrum analyses, measurement of room reverberation time, testing of loudspeaker response including THD, sound absorption effects, etc. Selection of equipment with due regard to costs can be eased by the purchase of a ‘‘university package’’ of sensing devices that can be applied with FFT and sound generation cards and special purpose computer programs.

Parallel Numeric Algorithms On Faster Computers

Parallel Numeric Algorithms On Faster Computers

Stress concentration in cone–cylinder intersection

The finite element method and shell theory were employed to investigate cone–cylinder shell intersections. The developed special-purpose computer program Sais (stress analysis in intersecting shells) was used for elastic stress analysis of branch connections. A comparison of calculated results with experimental data is presented. A parametric study of non-radial models of the cone–cylinder shell intersection subjected to internal pressure loading was performed. The intersections of thin and middle thickness shells were analysed. The results are presented in graphical form. Non-dimensional geometric and angular parameters are considered to analyse the effects of changing these parameters on stress ratios in the shell intersection.

Development of a Windows-based indoor air quality simulation software package

A Microsoft Windows-based indoor air quality (IAQ) simulation software package has been developed and has completed a small-scale beta test and quality assurance review. Tentatively named Simulation Tool Kit for Indoor Air Quality and Inhalation Exposure, or STKi for short, this package complements and supplements existing IAQ simulation packages and is designed mainly for advanced users. STKi Version 1 consists of a general-purpose simulation program and four stand-alone, special-purpose programs. The general-purpose program performs multi-zone, multi-pollutant simulations and allows gas-phase chemical reactions. With a large collection of models for sources, sinks, and air filters/cleaners, it can perform simulations for a wide range of indoor air pollution scenarios. The special-purpose programs implement fundamentally based models, which are often excluded from existing IAQ simulation programs despite their improved performance over statistical models. In addition to performing conventional IAQ simulation, which generates time–concentration profiles, STKi can estimate the adequate ventilation rate when certain air quality criteria are given, a unique feature useful for product stewardship and risk management. STKi will be developed in a cumulative manner. More special-purpose simulation programs will be added to the package. Key numerical methods used in STKi are discussed. Ways to convert the STKi programs into language-independent simulation modules that can be used by multi-pathway exposure models are also being explored.

Stresses in ellipsoidal pressure vessel heads with noncentral nozzle

The objective of this paper is further investigation of the shell intersection problem. The shell theory and finite element method are used for stress analysis of nozzle connections in ellipsoidal heads of the pressure vessels. Ellipsoidal heads having attached nozzles considerably displaced from the head axis are mainly considered. The features of the numerical procedure, structural modeling of nozzle-head shell intersections and SAIS special-purpose computer program are discussed. The results of stress analysis and parametric study of an ellipsoidal vessel head with a noncentral nozzle under internal pressure loading are presented.

On the buckling of cylindrical shells with through cracks under axial load

Presence of cracks or similar imperfections can considerably reduce the buckling load of a shell structure. In this paper, the buckling of cylindrical shells with through cracks has been studied. A general finite element model has been proposed, verified and applied to some novel cracked shell buckling problems for which documented results are not available. A special purpose program has been developed for generating finite elements models of cylindrical shells with cracks of varying length and orientation. The buckling behavior of cracked cylinders in tension and compression has been studied. The results of the analysis are presented in parametric form when it seems to be appropriate. Sensitivity of the buckling load to the crack length and orientation has also been investigated.

Snap-Through Buckling Analyses of Composite Shallow Spherical Shells

The purpose of this work is to present some numerical results on nonlinear, snap-through buckling of shallow spherical shells made of laminated composite materials under general static loading. Isotropic shells are covered as a special case of the general problem. A special-purpose finite-difference computer program has been developed. Moreover, the general-purpose computer program ANSYS has also been used. Effects of various material properties on the nonlinear behavior of the shells are investigated. One of the conclusions of the study is that ANSYS may yield erroneous results in some cases. Another conclusion is that the buckling curves of composite shallow spherical shells have a shape similar to that of the corresponding isotropic shell. This finding implies that the geometry of a shell may be an important factor in giving a characteristic shape to the buckling curve, at least for the shell parameters considered here.

Impact assessment of oncology research in the European Union

In this study the distribution of papers published by authors from the European Union (EU) in oncological journals was analysed, as was the impact of oncological research in the EU compared with that produced in other countries. Papers published during 1995 in the oncological journals listed by ISI (Institute for Scientific Information, Philadelphia, U.S.A.) were downloaded. The parameters of impact factor (IF), source country population and gross domestic product (GDP) were considered. An analysis of the key words, both those reported by the authors and those attributed by ISI, was carried out using a special purpose program. 36.5% of papers published in oncological journals come from the EU (the U.K., Italy, Germany and France ranking at the top) and 40.7% from the U.S.A. The mean IF was 2.4 for EU papers, 3.3 for the US and 2.4 for other countries. Our data confirm that smaller countries performed better than larger ones. The key words analysis shows that the leading fields of research were breast cancer for diseases, cisplatin for drugs and p53 for experimental studies. A standardisation of key words on behalf of journal editors is proposed.

A Mathematica Based Environment For AnalysisAnd Optimum Design Of Composite Structures

Tremendous advances have been made in the development of powerful computer algebra (CA) systems that are capable of performing complex computational tasks in a unified environment involving numerical and symbolic calculations, graphics, and animation. Using one such system, called Mathematica, the paper presents a computational environment as an alternative to the use of spreadsheets and special purpose programs in the structural design practice. The design requirements are entered as equations using essentially the same notation in which such equations appear in books and design manuals. The same set of equations can also be turned into an optimization problem by defining expressions for an objective function and suitable constraint functions. These ideas are illustrated by taking examples of optimum designs of reinforced concrete beams and composite laminates.

Theoretical analysis of composite shell intersections

In this study, a systematic approach is presented for the stress analysis of shell intersections made of composite materials. The finite element method used is based on a modified mixed formulation and two-dimensional laminated shell theory. The calculation algorithm and capabilities of the special-purpose computer program SAIS are discussed. The numerical and the experimental results are compared. A parametric study of intersecting composite laminated cylindrical shells was performed. The numerical results presented show the effects of specific properties of composite materials on stresses in shell intersections under internal pressure loading.

Power optimization of core-based systems by address bus encoding

This paper presents a solution to the problem of reducing the power dissipated by a digital system containing an intellectual proprietary core processor which repeatedly executes a special-purpose program. The proposed method relies on a novel, application-dependent low-power address bus encoding scheme. The analysis of the execution traces of a given program allows an accurate computation of the correlations that may exist between blocks of bits in consecutive patterns; this information can be successfully exploited to determine an encoding which sensibly reduces the bus transition activity. Experimental results, obtained on a set of special-purpose applications, are very satisfactory; reductions of the bus activity up to 64.8% (41.8% on average) have been achieved over the original address streams. In addition, data concerning the quality and the performance of the automatically synthesized encoding/decoding circuits, as well as the results obtained for a realistic core-based design, indicate the practical usefulness of the proposed power optimization strategy.

Solution of Ground Water Flow Problems with General Purpose and Special Purpose Computer Codes

AbstractIncreasingly, ground water hydrologists and engineers must solve saturated/unsaturated flow and transport problems. The unsaturated component of flow is especially important when considering transport of contaminants that originate from surface or near‐surface sources such as waste spill sites, landfills, and hazardous waste storage sites. Numerical solution of such problems has been accomplished with special purpose computer programs developed for solution of unsaturated flow problems. However, general purpose partial differential equation (PDE) solvers also exist, which often provide greater model flexibility. In this paper, the performance of PDE2D, a general PDE solver, and SWMS_2D, a special purpose program, are compared for solution of unsaturated flow and transport problems. Both programs accurately calculated changes in water volume in the flow domain for four examples, but PDE2D did not calculate boundary fluxes as well as SWMS_2D, resulting in high mass balance errors. However, PDE2D yielded a smoother solution of the example solute transport problem, despite a large mass balance error. SWMS_2D offers ease of use and excellent mass balances while PDE2D offers the user greater flexibility in terms of the types of problems solved, and a grid generator that ensures that the element size and distribution of elements are appropriate for a given problem.

Approximation of spectrum alpha peaks by robust estimation

A fitting method based on the robust approach M-Huber's estimate has been developed to analyze alpha spectra. It is shown that the approximation depends on the method of estimation for a selected model. The advantage of this technique is demonstrated by processing experimental alpha spectra using a special purpose computer program.

Stress Analysis of Shell Intersections With Torus Transition Under Internal Pressure Loading

Thin shell theory and finite element method were used to investigate shell intersections with torus transition. The developed special-purpose computer program SAIS is employed for elastic stress analysis of the shell intersections. Comparison of calculated results with experimental data are presented. The parametric study of models for the radial nozzle connections in shells under internal pressure loading was performed. The results are presented in graphical form. Nondimensional geometric parameters are considered to analyze the effects of changing these parameters on stress ratios in the shell intersections.

A Course in Computational Nonassociative Algebra

This paper describes a two-semester graduate-level course designed during 1995 at Universidade Federal do Rio Grande do Sul (UFRGS). A major goal of the course was to introduce several problems in the theory of nonassociative algebra and to show how computer algebra methods can be used to gain insight. The course utilized AXIOM as well as the special purpose program Albert.

Simulation in Manufacturing.

From the Publisher: Simulation software tools have changed from special purpose programming languages to interactive PC systems one of which, called AIM, was developed by the Pritsker Corporation in alliance with IBM and is highlighted in this book for allowing simulation modellers to speak in manufacturing rather than computer terms. The book gives a balanced account of various skills which the practising simulation analyst must possess for successful modelling, regardless of which system is employed. As well as modelling itself, these include aspects of statistics, queuing theory and experimentation to which suitable references for deeper study are given.