Engineering Analysis Tools Research Articles

A time‐dependent incompressible viscous BEM for moderate Reynolds numbers

AbstractThe boundary element method is applied to transient viscous incompressible flow. The time‐domain formulation allows a boundary‐only solution for linear Stokes flow. For higher speed flows in which the non‐linear convective effects cannot be ignored, a volume integral must be retained. However, the introduction of reference velocities often limits the non‐linear region to the vicinity of obstacles or bounding surfaces. Additionally, the volume terms are rewritten to eliminate the need for the calculation of velocity gradients. A general purpose numerical implementation of this new formulation then produces a very attractive tool for engineering analysis. This implementation includes a Newton‐Raphson algorithm, permitting accurate solutions up to the moderate Reynolds number range. Several numerical examples are provided to validate the present approach.

An integration and analysis tool for engineers

System design methodologies can greatly help the understanding of complex manufacturing situations. The IDEF0 structured analysis method is one of the favoured tools for industry.

Design analysis through techniques of parametric cost estimation

This paper focuses on the parametric model as tool for design engineering analysis. The technique is made relevant to routine, every-day living and proceeds to the engineering design function with a case study of over 4000 instances where the parametric model provided estimates closer to actual costs than the traditional ‘bottom-ups’ means to cost estimation in an aerospace industrial application.

AN INTERACTIVE HYBRID (SYMBOLIC-NUMERIC) SYSTEM APPROACH TO NEAR OPTIMAL DESIGN OF MECHANICAL COMPONENTS

Abstract A hybrid (symbolic-numeric) system, referred to as OPTDEX, (OPTIMAL DESIGN EXPERT) for the optimal design or mechanical components and systems has been developed. The system is written in Golden Common LISP and IBM Professional (Ryan-McFarland) FORTRAN for execution on the IBM PC/AT microcomputer. Graphical output has been implemented using the Graphical Kernel System (GKS) standard. This microcomputer-based implementation makes the system particularly attractive as an easily accessible, low cost engineering analysis and design tool. Experience with the system indicates that the time required to achieve, at least, partially optimized engineering design solutions is similar to that which may be expected with standard, nonoptimization-based, microcomputer computation. Any added computational time may be justified and subsequently offset by increased long term design efficacy.

Interactive hybrid (symbolic-numeric) system approach to near optimal design of mechanical components

A hybrid symbolic-numeric system, referred to as OPTDEX, (Optimal Design Expert) for the optimal design of mechanical components and systems has been developed. The system is written in Golden Common LISP and IBM Professional (Ryan-McFarland) FORTRAN for execution on the IBM PC/AT microcomputer. Graphical output has been implemented using the Graphical Kernal System (GKS) standard. This microcomputer-based implementation makes the system particularly attractive as an easily accessible, low-cost engineering analysis and design tool.

Use of Electronic Worksheets for Calculation of Stagewise Solvent Extraction Processes

Abstract The electronic worksheet, a powerful new tool for engineering analysis, is used to calculate flowsheets for stagewise solvent extraction processes. The algorithms presented give the component concentration of each stage at steady-state conditions and an estimate of the time to reach steady state. Any number of inlet and exit streams can be included and a different distribution ratio can be specified for each stage. The procedure is illustrated using a nuclear waste flowsheet. Although this paper deals with stagewise solvent extraction, it shows the utility of the electronic worksheet for many types of scientific and engineering calculations.

SMART: Scientific database management and engineering analysis routines and tools

Development of user-friendly and flexible scientific programs is a key to their widespread usage, extension and maintenance. The paper describes capabilities of a library called SMART that can be used in the development of such programs. The library contains many interactive programming aids and screen management utilities that can help in development of the user interfaces. A very flexible full screen data editor is available. Many other subroutines are available, such as vector and matrix operations, in-core data management, out-of-core numerical and relational database management, and graphics. The library is not advocated to be comprehensive. It is meant to show the kind of capabilities that are needed in development and maintenance of scientific programs. Such libraries can be of particular use in research on computational methods for scientific applications.

Evaluation of finite element system architectures

The finite element method is a powerful engineering analysis tool. However, the scope and size of the problems solved are limited by the capabilities and costs of computers currently used. New computer architectures with parallel processing capabilities can exploit the parallelism in the finite element method. Because of the large number of alternative hardware and software configurations and the high costs incurred in the development of such systems, a methodology is needed to compare proposed finite element systems without implementing either hardware or software. This paper presents such a methodology. System architectures are evaluated by simulating the execution of the finite element software on the hardware. Hardware is represented as a set of processors and resources, while the software is modeled as a set of computational tasks organized into an acyclic directed graph. The simulation is performed by scheduling routines. The result of the scheduling routines is a schedule consisting of task-processor assignments and task starting and finishing times. Also, processor and resource utilization levels are generated. These results provide a means of comparing proposed finit element systems.

Noise transmission loss of a rectangular plate in an infinite baffle

An improved analytical procedure has been developed that allows for an efficient solution of the finite plate noise transmission problem. The plate is modeled with classical thin plate theory and is assumed to be simply supported on all four sides. The incident acoustic pressure is modeled as a plane wave impinging on the plate at an arbitrary angle of incidence. Assuming the radiation damping is negligible compared to the structural damping, the incident, reflected, and transmitted pressures are approximated by the blocked pressure which allows the plate vibrations to be calculated by a normal-mode approach. A Green's function integral equation is used to link the plate vibrations to the transmitted farfield sound waves. The incident and transmitted acoustic powers are calculated by integrating the incident and transmitted intensities over their appropriate areas, and transmission loss is calculated from the ratio of incident to transmitted acoustic powers. The result is a versatile research and engineering analysis tool that not only enables the determination of which modes are dominating the noise transmission, but also allows for the problem to be broken down into its composite parts. This includes determining what the modal behavior is, such as, coupling between the incident noise and the plate vibrations; the plate resonance behavior; and the coupling between the plate vibrations and the transmitted noise. The effect of varying the angle of incidence and the farfield directivity can also be determined from the analytical model. The analysis approach was developed to study propeller noise transmission into aircraft and is seen to be equally applicable to sound transmission through building walls, floors, and windows.

A Software Package For Electric EngineeringAnalysis And Design

A new software package developed in the Electronic Department of the University of Genova is presented. SAM-1 program is able to perform digital simulation of electric networks, control systems, electrical drives and physical systems described by means of linear and non linear differential equation sets. Particularly, the author is developing a library of macromodels for all the most significant power electronic circuital topologies and for electric machines. The implementation methodologies and two macromodels are presented and the simulation results are discussed to verify that SAM-1 program can be successfully used as a CAD tool for the design and analysis of electric circuits and particularly the power electronics ones. INTRODUCTION In these last years the software packages have become a necessary tool for engineering analysis and design. Particularly, electric engineering general purpose software packages such as EMTP, Saber, ELDO [1] are heavily employed in order to verify the operating conditions of electrical plants, transmission systems and electrical drives with relevant control circuits. They can be also successfully used to design innovative electrical configurations or to analyze misoperating conditions in order to realize protective relais coordination. However, special purpose software packages sometimes can be developed if particular topologies have to be studied, if calculation times become unreasonably long, or if convergence problems arise. Transactions on Engineering Sciences vol 3, © 1993 WIT Press, www.witpress.com, ISSN 1743-3533 106 Software Applications in Electrical Engineering In this paper a new software tool developed in the Electronic Department of the University of Genova, called SAM-1 Program, will be presented [2]. This CAD tool consists of an evolution of the CSS1 Program, a software package oriented to the analysis of control and regulation systems. SAM-1 PROGRAM CHARACTERISTICS SAM-1 Program is a general purpose package able to perform digital simulation of electric networks, control systems, electrical drives and all physical systems containing both linear and non-linear elements. Substantially, SAM-1 numerically solves high order linear and non linear differential equations sets using Runge-Kutta method both of second and fourth order. If the 2 order Runge-Kutta method is utilized, analyzing a status equations set: x = ax + bn with x(0) = XQ (1) fixing a certain At integration step and starting from x^, it is possible to obtain x as Xn + l = Xn + x'n At (2) where x^ is the weighed derivative equal to: x'n = Xx + i/2 = x (nAt + 1/2 At) = Xn + in • 1/2 At (3) A graphic interpretation in the case of only one equation may be useful as shown in Fig. 1. If particular systems have to be studied, the 2° order RungeKutta method can result inadequate. Infact, approximation becomes too bad if integration steps are too large. Thus a 4^ order Runge-Kutta method has been included. To briefly explain this method, starting from a point (0, yo) and fixed an integration step, if the equation to solve is: y = f(x,y) (4) it is necessary to obtain: Transactions on Engineering Sciences vol 3, © 1993 WIT Press, www.witpress.com, ISSN 1743-3533 Software Applications in Electrical Engineering 107

Bessemer steel in Europe and America

The mechanical integrity of the soft tissue structures supporting the fetus may play a role in maintaining a healthy pregnancy and triggering the onset of labor. Currently, the level of mechanical loading on the uterus, cervix, and fetal membranes during pregnancy is unknown, and it is hypothesized that the over-stretch of these tissues contributes to the premature onset of contractility, tissue remodeling, and membrane rupture, leading to preterm birth. The purpose of this review article is to introduce and discuss engineering analysis tools to evaluate and predict the mechanical loads on the uterus, cervix, and fetal membranes. Here we will explore the potential of using computational biomechanics and finite element analysis to study the causes of preterm birth and to develop a diagnostic tool that can predict gestational outcome. We will define engineering terms and identify the potential engineering variables that could be used to signal an abnormal pregnancy. We will discuss the translational ability of computational models for the better management of clinical patients. We will also discuss the process of model validation and the limitations of these models. We will explore how we can borrow from parallel engineering fields to push the boundary of patient care so that we can work toward eliminating preterm birth.