Graphical workstation capability for reliability modeling

In addition to computational capabilities, software tools for estimating the reliability of fault-tolerant digital computer systems must also provide a means of interfacing with the user. Described here is the new graphical interface capability of the hybrid automated reliability predictor (HARP), a software package that implements advanced reliability modeling techniques. The graphics oriented (GO) module provides the user with a graphical language for modeling system failure modes through the selection of various fault-tree gates, including sequence-dependency gates, or by a Markov chain. By using this graphical input language, a fault tree becomes a convenient notation for describing a system. In accounting for any sequence dependencies, HARP converts the fault-tree notation to a complex stochastic process that is reduced to a Markov chain, which it can then solve for system reliability. The graphics capability is available for use on an IBM-compatible PC, a Sun, and a VAX workstation. The GO module is written in the C programming language and uses the graphical kernal system (GKS) standard for graphics implementation. The PC, VAX, and Sun versions of the HARP GO module are currently in beta-testing stages

Beware the Non-uniqueness of Einstein Rings

We explain how an approximation to the rings formed by the host galaxies in lensed QSOs can be inferred from the QSO data alone. A simple ring image can be made from any lens model by a simple piece of computer graphics: just plot a contour map of the arrival-time surface with closely-spaced contours. We go on to explain that rings should be (a) sensitive to time-delay ratios between different pairs of images, but (b) very insensitive to H_0. We illustrate this for the well-known quads 1115+080 and 1608+656.Comment: To appear in AJ (circa Aug 2001

Sketchy rendering for information visualization

We present and evaluate a framework for constructing sketchy style information visualizations that mimic data graphics drawn by hand. We provide an alternative renderer for the Processing graphics environment that redefines core drawing primitives including line, polygon and ellipse rendering. These primitives allow higher-level graphical features such as bar charts, line charts, treemaps and node-link diagrams to be drawn in a sketchy style with a specified degree of sketchiness. The framework is designed to be easily integrated into existing visualization implementations with minimal programming modification or design effort. We show examples of use for statistical graphics, conveying spatial imprecision and for enhancing aesthetic and narrative qualities of visual- ization. We evaluate user perception of sketchiness of areal features through a series of stimulus-response tests in order to assess users’ ability to place sketchiness on a ratio scale, and to estimate area. Results suggest relative area judgment is compromised by sketchy rendering and that its influence is dependent on the shape being rendered. They show that degree of sketchiness may be judged on an ordinal scale but that its judgement varies strongly between individuals. We evaluate higher-level impacts of sketchiness through user testing of scenarios that encourage user engagement with data visualization and willingness to critique visualization de- sign. Results suggest that where a visualization is clearly sketchy, engagement may be increased and that attitudes to participating in visualization annotation are more positive. The results of our work have implications for effective information visualization design that go beyond the traditional role of sketching as a tool for prototyping or its use for an indication of general uncertainty

Calculating an upper bound on the finishing time of a group of threads executing on a GPU: a preliminary case study

Graphics processor units (GPUs) today can be used for computations that go beyond graphics and such use can attain a performance that is orders of magnitude greater than a normal processor. The software executing on a graphics processor is composed of a set of (often thousands of) threads which operate on different parts of the data and thereby jointly compute a result which is delivered to another thread executing on the main processor. Hence the response time of a thread executing on the main processor is dependent on the finishing time of the execution of threads executing on the GPU. Therefore, we present a simple method for calculating an upper bound on the finishing time of threads executing on a GPU, in particular NVIDIA Fermi. Developing such a method is nontrivial because threads executing on a GPU share hardware resources at very fine granularity

Design Guidelines for Agent Based Model Visualization

In the field of agent-based modeling (ABM), visualizations play an important role in identifying, communicating and understanding important behavior of the modeled phenomenon. However, many modelers tend to create ineffective visualizations of Agent Based Models (ABM) due to lack of experience with visual design. This paper provides ABM visualization design guidelines in order to improve visual design with ABM toolkits. These guidelines will assist the modeler in creating clear and understandable ABM visualizations. We begin by introducing a non-hierarchical categorization of ABM visualizations. This categorization serves as a starting point in the creation of an ABM visualization. We go on to present well-known design techniques in the context of ABM visualization. These techniques are based on Gestalt psychology, semiology of graphics, and scientific visualization. They improve the visualization design by facilitating specific tasks, and providing a common language to critique visualizations through the use of visual variables. Subsequently, we discuss the application of these design techniques to simplify, emphasize and explain an ABM visualization. Finally, we illustrate these guidelines using a simple redesign of a NetLogo ABM visualization. These guidelines can be used to inform the development of design tools that assist users in the creation of ABM visualizations.Visualization, Design, Graphics, Guidelines, Communication, Agent-Based Modeling

Representations of facial expressions since Darwin

Darwin’s book on expressions of emotion was one of the first publications to include photographs (Darwin, 1872). The inclusion of expression photographs meant that readers could form their own opinions and could, like Darwin, survey others for their interpretations. As such, the images provided an evidence base and an ‘open source’. Since Darwin, increases in representativeness and realism of emotional expressions come from the use of composite images, colour, multiple views and dynamic displays. Research on understanding emotional expressions has been aided by the use of computer graphics to interpolate parametrically between different expressions and to extrapolate exaggerations. This review tracks the developments in how emotions are illustrated and studied and considers where to go next.Publisher PDFPeer reviewe

A Design-Build-Test-Fly Project Involving Modeling, Manufacturing, and Testing

This paper describes a junior-level semester-long class project for students in Fluid Mechanics courses. The goals of the project are to introduce students to engineering design, project management, and to incorporate material from other courses in engineering graphics, numerical methods, instrumentation and measurements, and manufacturing processes in a single project. The project focuses on airfoil design using computational tools, and the main emphasis lies on verification of results obtained from computational methods with experimentally measured values. Students will use the airfoil shape they select to make wings to go on a model foam glider. The final part of the project will be staged as a competition where student teams vie to see whose glider can fly the furthest under standard launching conditions

Issues in multi-media information networks

In an integrated service environment, where users exchange various types of aural and visual information, networks should appear friendly to its users providing tools for management of multi-media information. Networks should also efficiently satisfy diverse performance requirements of different information being exchanged.In this paper we present new architecture for integrated service networks being investigated and developed by the Distributed Computation and Communication Group at the Department of Computer Science in the Columbia University. Research efforts are devoted to developing both (1) document management software to allow users to manipulate and relate text/graphics/voice information in a dynamic way, and (2) a tree network architecture for reliable and efficient exchange of multi-media information