Advances in Engineering Software (1978)最新文献

WAVEGIDE is an interactive program which, when used in conjunction with IMSL's PDE/PROTRAN, can solve waveguide problems on arbitrary cross-sections, with variable permittivity and permeability. The user only has to answer a series of basic questions about his problem, posed in engineering terms, and all propagating modes in a specified interval are calculated, and the corresponding electric and magnetic fields are plotted.

Product models offer a promising method for structuring data describing a building in the databases which will be used in the computer integrated construction process of the next century.

In order to define product model standards which completely describe modern buildings, many years of theoretical and experimental work are needed. In order to ensure industrial backing for the work needed to develop full standards, it seems prudent to organize such work on a step by step basis where partial standards can be agreed on and implemented rather quickly.

In addition to the international work being carried out within the ISO/STEP working group, it is possible to obtain results on a national basis, provided there is a large enough consensus within the construction industry on what ought to be done.

In Finland the basic principles of a building product model, the RATAS-model, have been defined. The model uses a data model consisting of such concepts as objects, attributes, relationships and it describes the building with a five-level abstraction hierarchy starting with the building object. At present a number of prototypes are being developed based on the RATAS-model. These prototypes are developed using different types of application software: relational databases, hypermedia, drafting systems etc., but they all utilize the same conceptual information structure.

This paper presents a Turbo-Basic program that implements a revised version of a new algorithm for the fast and optimum solution of the general linear minimax approximation problem. The algorithm proceeds iteratively and terminates when the global minimum value of the objective function is reached. The initial point may be selected arbitrarily or it may be optimally determined through a linear method to speed up algorithmic convergence. This algorithm is much faster and requires less storage than other approximation techniques. The program is implemented on an IBM-PC AT and tested by a number of approximation problems. Analytical examples are presented to illustrate how the program is used and the effectiveness of the algorithm.

A Computer Assisted Learning (CAL) package has been developed for use on an IBM/PC/XT/AT or compatible machine equipped with a Color Graphics Adapter (CGA). It provides brief descriptions of

• 1.

  (i) important properties of the Gumbel distribution,

• 2.

  (ii) good methods for estimating its parameters and related solution procedures,

• 3.

  (iii) techniques for evaluating the goodness-of-fit, and

• 4.

  (iv) needed formulas for calculating the T-year event and its variance (or standard deviation).

All the methods/techniques described have been translated into corresponding subroutines included in the package to make it readily suitable for practical applications in flood frequency analysis. Depending on his technical knowledge, the user can use the package for learning all the important concepts, for data analysis alone, or for simulation studies.

The paper describes the characteristics of the package and how it is used through some illustrative examples.

The present streamline visualization program is based on the technique of mapping the physical domain to a rectangular block. The streamline computation proceeds by integrating the mapped velocity vectors in isoparametric cells and plotting the coordinates of the streamlines thus obtained. The mapping and interpolation use multilinear functions, and the streamline equations are integrated by the classical Runge-Kutta method with a heuristic strategy for stepsize selection. An example integrating the streamlines in the solution of a vortical flowfield over a delta wing at angle of attack demonstrates the use of the program.