FEView: An interactive visualization tool for finite elements

This paper presents a finite element visualization facility, FEView, which has been implemented based upon an object-oriented graphics library. The visualization tool works as an external module to an interactive program Geomview for viewing and manipulating geometric objects. The graphical user interface has been built on top of the Forms Library, a graphical user interface toolkit for Silicon Graphics workstations.

A finite element mesh can be considered as a collection of faces with edges, wire frame, or point cloud, and the corresponding numerical results gained through finite element analyses can be visualized via color shading and field icons (such as arrows) on the geometric shapes. Also, a scalar field can be represented as a weather map to highlight color shading domains with scalar values falling into the range of interest. Numerical results for two-dimensional cases can be shown with three-dimensional effects by using values of the scalar field. FEView provides animation control over single frame stepping and adjustable speed playing. It has been equipped with geometry operation functionality, in which a particular part of an object can be obtained by specifying material indices, element numbers, and cutting boxes. In local analysis mode, FEView is able to provide local information about finite element objects by picking up the position of interest via mouse manipulation.     

Visual interactive modelling and manpower planning

Following some years extensive use of a Staff Simulation Model by the Personnel Department of Barclays Bank to demonstrate the effect of different staffing policies, it was felt that there was a need to improve the model, both technically and from the point of view of the presentation of the results. It was decided to use Visual Interactive Modelling Systems as in this way, the changes in the assumption could be seen in a colour, pictorial form on a screen. The results could also be shown diagrammatically either on the screen or as a screen print-out. The pictorial output had an immediate impact, and was felt to be a vast improvement on the large number of sheets of numerical computer print-outs previously produced.     

Visual interactive simulation: A methodological perspective

The ideas and methods of Visual Interactive Simulation (VIS) are nearly fifteen years old, yet are still often misunderstood or misrepresented. It is argued that VIS is primarily a methodology, a way of solving problems with simulation modeling, not necessarily a way of building simulation models. Two distinct methodologies are identified, namely active and passive VIS. It is shown that simulation languages and packages tend to implicitly employ a particular methodology, and that each approach requires a different problem-solving life cycle. Present research, and necessary future research, are reviewed from our methodological perspective.     

An interactive programming system for Pascal

Interactive program development tools are being increasingly recognized as helpful in the construction of programs. This paper describes an integrated incremental program development system for Pascal called Pathcal. Pathcal contains facilities for creation, editing, debugging and testing of procedures and programs. The system facilities are all Pascal procedures or variables and because of this allows the programmer to program the system in itself.This work was supported by The National Swedish Board of Technical Development (STU) under contract dnr. 78-4167.     

An interactive algorithm for nonlinear vector optimization

In this paper an interactive algorithm for nonlinear vector optimization problems is presented. This algorithm decides, after solving only two optimization problems, whether or not there are efficient points in the feasible set. In the latter case, an efficient point depending on parameters is automatically computed, and (which is much more important) efficient points for each parameter can be calculated by this procedure.     

Stability and monotonicity for interactive Markov chains

In a Markov chain model of a social process, interest often centers on the distribution of the population by state. One question, the stability question, is whether this distribution converges to an equilibrium value. For an ordinary Markov chain (a chain with constant transition probabilities), complete answers are available. For an interactive Markov chain (a chain which allows the transition probabilities governing each individual to depend on the locations by state of the rest of the population), few stability results are available. This paper presents new results. Roughly, the main result is that an interactive Markov chain with unique equilibrium will be stable if the chain satisfies a certain monotonicity property. The property is a generalization to interactive Markov chains of the standard definition of monotonicity for ordinary Markov chains.     

An interactive program for finite incidence structures

It has been shown (see [3]) that every finite incidence structure can be represented in a suitable way by a polynomial over a convenient finite field. In this paper we present a FORTRAN interactive program which examines the incidence structure associated to a given polynomial over GF(9). Further, a second program is exhibited, which determines a complete system of mutually orthogonal latin squares related to a polynomial associated to a projective plane of order nine.     

An interactive approach for Bi-attribute multi-item auctions

The advances in the technological infrastructure and in the Internet led electronic auctions to become popular. With online sites, people buy/sell inexpensive products/services through auctions. In this paper, we develop an interactive approach that provides aid to both the buyer and the bidders in a bi-attribute, multi-item auction environment. Our approach is applicable for both reverse and forward auctions. We test our approach for underlying linear preference functions of the buyer. We also adapt it as a heuristic for the case the buyer has a nonlinear preference function. The test results show that our approach works well.     

An interactive approach for multiobjective decision making

We develop an interactive approach for multiobjective decision-making problems, where the solution space is defined by a set of constraints. We first reduce the solution space by eliminating some undesirable regions. We generate solutions (partition ideals) that dominate portions of the efficient frontier and the decision maker (DM) compares these with feasible solutions. Whenever the decision maker prefers a feasible solution, we eliminate the region dominated by the partition ideal. We then employ an interactive search method on the reduced solution space to help the DM further converge toward a highly preferred solution. We demonstrate our approach and discuss some variations.     

An interactive approach for vector optimization problems

This paper deals with an interactive approach for vector optimization problems. The best compromise solutions are obtained using one of the methods which depends on the global preference, namely Geoffrion's method. The stability set of the first kind is analyzed and used to reduce the parametric space of the problem. An example is given for the sake of illustration.     

An interactive model for the layout of buildings

The TOPAZ model and its derivatives, TOPLAY and TOPMET which have been developed for sketch planning design of buildings, are presented and their use is illustrated by application to a 40 000 m² insurance building. TOPMET introduces a completely new approach to solve the inherently difficult quadratic assignment layout problem. The new approach is relatively simple and readily adaptable to microcomputer usage in an interactive form using colour graphics. It also exhibits artificial intelligence behaviour and offers further development possibilities. The paper concludes that while the sketch planning phase of multi-storey building design has received relatively little attention from computer modellers to date, the use of models such as those described in conjunction with inexpensive colour graphic microcomputers is now set for extensive development and application.     

An interactive visual simulation system for industrial management

This paper describes a discrete event interactive simulation system which allows a user to watch the progress of a simulation model on a visual display terminal. The user may interact with the model in a flexible manner, in order to explore the consequence of alternative decisions or strategies. Output from the simulation may be directed, in an animated form, to a refresh display computer graphics screen, a black and white visual display unit or an intelligent colour visual display divice. The interactive system has been specifically designed to assist in decision making processes associated with industrial management problem situations.     

An interactive method for multiple-objective mathematical programming problems

An interactive method is developed for solving the general nonlinear multiple objective mathematical programming problems. The method asks the decision maker to provide partial information (local tradeoff ratios) about his utility (preference) function at each iteration. Using the information, the method generates an efficient solution and presents it to the decision maker. In so doing, the best compromise solution is sought in a finite number of iterations. This method differs from the existing feasible direction methods in that (i) it allows the decision maker to consider only efficient solutions throughout, (ii) the requirement of line search is optional, and (iii) it solves the problems with linear objective functions and linear utility function in one iteration. Using various problems selected from the literature, five line search variations of the method are tested and compared to one another. The nonexisting decision maker is simulated using three different recognition levels, and their impact on the method is also investigated.     

Methods for the visualization of clustered climate data

Summary  Increasing amounts of large climate data require new analysis techniques. The area of data mining investigates new paradigms and methods including factors like scalability, flexibility and problem abstraction for large data sets. The field of visual data mining in particular offers valuable methods for analyzing large amounts of data intuitively. In this paper we describe our approach of integrating cluster analysis and visualization methods for the exploration of climate data. We integrated cluster algorithms, appropriate visualization techniques and sophisticated interaction paradigms into a general framework.     

Magnetic Eigenmaps for the visualization of directed networks

We propose a framework for the visualization of directed networks relying on the eigenfunctions of the magnetic Laplacian, called here Magnetic Eigenmaps. The magnetic Laplacian is a complex deformation of the well-known combinatorial Laplacian. Features such as density of links and directionality patterns are revealed by plotting the phases of the first magnetic eigenvectors. An interpretation of the magnetic eigenvectors is given in connection with the angular synchronization problem. Illustrations of our method are given for both artificial and real networks.