Philip W. Grant

An Empirical Study on Using Visual Embellishments in Visualization

In written and spoken communications, figures of speech (e.g., metaphors and synecdoche) are often used as an aid to help convey abstract or less tangible concepts. However, the benefits of using rhetorical illustrations or embellishments in visualization have so far been inconclusive. In this work, we report an empirical study to evaluate hypotheses that visual embellishments may aid memorization, visual search and concept comprehension. One major departure from related experiments in the literature is that we make use of a dual-task methodology in our experiment. This design offers an abstraction of typical situations where viewers do not have their full attention focused on visualization (e.g., in meetings and lectures). The secondary task introduces “divided attention”, and makes the effects of visual embellishments more observable. In addition, it also serves as additional masking in memory-based trials. The results of this study show that visual embellishments can help participants better remember the information depicted in visualization. On the other hand, visual embellishments can have a negative impact on the speed of visual search. The results show a complex pattern as to the benefits of visual embellishments in helping participants grasp key concepts from visualization.

Using Competing Ant Colonies to Solve k-way Partitioning Problems with Foraging and Raiding Strategies

The self organizing properties of ant colonies are employed to tackle the classical combinatorial optimization problem of graph partitioning. The graph is mapped onto an artificial environment in a manner that preserves the structural information. Ants from a number of colonies compete for resources. This leads to a restructuring of the global environment corresponding to a good partition. On the example graphs, this is shown to outperform the current best algorithms which are based on recursive bisection techniques.

Facial expression recognition in dynamic sequences

Automatic facial expression analysis aims to analyse human facial expressions and classify them into discrete categories. Methods based on existing work are reliant on extracting information from video sequences and employ either some form of subjective thresholding of dynamic information or attempt to identify the particular individual frames in which the expected behaviour occurs. These methods are inefficient as they require either additional subjective information, tedious manual work or fail to take advantage of the information contained in the dynamic signature from facial movements for the task of expression recognition.In this paper, a novel framework is proposed for automatic facial expression analysis which extracts salient information from video sequences but does not rely on any subjective preprocessing or additional user-supplied information to select frames with peak expressions. The experimental framework demonstrates that the proposed method outperforms static expression recognition systems in terms of recognition rate. The approach does not rely on action units (AUs), and therefore, eliminates errors which are otherwise propagated to the final result due to incorrect initial identification of AUs. The proposed framework explores a parametric space of over 300 dimensions and is tested with six state-of-the-art machine learning techniques. Such robust and extensive experimentation provides an important foundation for the assessment of the performance for future work. A further contribution of the paper is offered in the form of a user study. This was conducted in order to investigate the correlation between human cognitive systems and the proposed framework for the understanding of human emotion classification and the reliability of public databases. HighlightsExtraction of dynamic signals via a parametric space to improve the automatic facial expression recognition rate.An objective comparison with systems utilizing static apex expression recognition.The use of a visualisation technique for the analysis and initial understanding of facial feature data.An intuitive user study to investigate the correlation between human perception and machine vision.

Open architecture for computer-aided control engineering

Some guiding principles for the design of open systems suitable for computer-aided control engineering are presented. Some possible architectures are considered, and an assessment is made of the available technologies that might be suitable for an open environment. An analogy is made with the requirements for computer-aided software engineering, for which a reference model has already been developed. It is concluded that such a model might well provide a clear definition of what is needed in computer-aided control engineering.<<ETX>>

Coordinate free programming of computational fluid dynamics problems

It has long been acknowledged that the development of scientific applications is in need of better software engineering practices. Here we contrast the difference between conventional software development of CFD codes with a method based on coordinate free mathematics. The former approach leads to programs where different aspects, such as the discretisation technique and the coordinate systems, can get entangled with the solver algorithm. The latter approach yields programs that segregate these concerns into fully independent software modules. Such considerations are important for the construction of numerical codes for practical problems. The two approaches are illustrated on the coating problem: the simulation of coating a wire with a polymer.

Fault diagnosis for industrial printers using case-based reasoning

Abstract The objective of this paper is to discuss first-hand experience of developing a fault-diagnostic application using a commercially available case-based reasoning (CBR) software tool. The paper will analyse the problem domain, discuss the need for a computing solution, compare two different computing approaches (rule-based systems and CBR), and state the effects and potential benefits to industry of introducing such systems.

Parallel computation of two‐dimensional rotational flows of viscoelastic fluids in cylindrical vessels

The numerical simulation of two‐dimensional incompressible complex flows of viscoelastic fluids is presented. The context is one, relevant to the food industry (dough kneading), of stirring within a cylindrical vessel, where stirrers are attached to the lid of the vessel. The motion is driven by the rotation of the outer vessel wall, with various stirrer locations. With a single stirrer, both a concentric and an eccentric configuration are considered. A double‐stirrer eccentric case, with two symmetrically arranged stirrers, is also contrasted against the above. A parallel numerical method is adopted, based on a finite element semi‐implicit time‐stepping Taylor‐Galerkin/pressure‐correction scheme. For viscoelastic fluids, constant viscosity Oldroyd‐B and two shear‐thinning Phan‐Thien/Tanner constitutive models are employed. Both linear and exponential models at two different material parameters are considered. This permits a comparison of various stress, shear and extensional properties and their respective influences upon the flow fields generated. Variation with increasing speed of vessel and change in mixer geometry are analysed with respect to the flow kinematics and stress fields produced. Optimal kneading scenarios are commended with asymmetrical stirrer positioning, one‐stirrer proving better than two. Then, models with enhanced strain‐hardening, amplify levels of localised maxima in rate‐of‐work done per unit power consumed. Simulations are conducted via distributed parallel processing, performed on work‐station clusters, employing a conventional message passing protocol (PVM). Parallel results are compared against those obtained on a single processor (sequential computation). Ideal linear speed‐up with the number of processors has been observed.

A graphical pre-processor for computer-aided control system design

Features in the design of a graphical man-machine interface for pre-processing the inputs to computer-aided control system design software are described in this paper. The primary objective is to allow the control engineer to communicate with a modem graphics workstation in a natural, familiar and friendly way, by means of block diagrams, signal flow graphs and standard mathematical text. Graphical methods for the input and output of these are described. Transformations between different system descriptions are considered which allow all algebraic manipulations and reductions to be performed on signal flow graphs. For these manipulations, rule-based methods are shown to be effective. The possibility of using symbolic computation languages for algebraic operations is also considered.

COARSE GRAIN PARALLEL FINITE ELEMENT SIMULATIONS FOR INCOMPRESSIBLE FLOWS

Parallel simulation of incompressible fluid flows is considered on networks of homogeneous workstations. Coarse-grain parallelization of a Taylor–Galerkin/pressure–correction finite element algorithm are discussed, taking into account network communication costs. The main issues include the parallelization of system assembly, and iterative and direct solvers, that are of common interest to finite element and general numerical computation. The parallelization strategies are implemented on a Sun workstation cluster using the PVM (Parallel Virtual Machine) message passing library. Test results are obtained with a maximum of nineteen workstations and various PVM configurations are exhibited. Parallel efficiency close to ideal has been achieved for some strategies adopted. It is suggested that loadbalancing may not always be beneficial on distributed platforms with broadcasting communication connection. c

Experiences of parallelising finite-element problems in a functional style

Experiences are described of parallelizing a functional finite‐element program (written in Haskell) for the solution of computational fluid‐dynamics problems. A transformation prototyping approach using a system developed at the University of York, which simulates idealised parallel machines on a conventional sequential workstation, is presented. In this paper we demonstrate: (a) the relative simplicity of the functional approach for parallelizing a complex program compared with the conventional procedural approach; (b) the suitability of functional languages for prototyping parallel algorithms to improve an implementation; and (c) the considerable assistance provided by the simulator.