Topological models for boundary representation: a comparison with n-dimensional generalized maps

In boundary representation, a geometric object is represented by the union of a ‘topological’ model, which describes the topology of the modelled object, and an ‘embedding’ model, which describes the embedding of the object, for instance in three-dimensional Euclidean space. In recent years, numerous topological models have been developed for boundary representation, and there have been important developments with respect to dimension and orientability. In the main, two types of topological models can be distinguished. ‘Incidence graphs’ are graphs or hypergraphs, where the nodes generally represent the cells of the modelled subdivision (vertex, edge, face, etc.), and the edges represent the adjacency and incidence relations between these cells. ‘Ordered’ models use a single type of basic element (more or less explicitly defined), on which ‘element functions’ act; the cells of the modelled subdivision are implicitly defined in this type of model. In this paper some of the most representative ordered topological models are compared using the concepts of the n-dimensional generalized map and the n-dimensional map. The main result is that ordered topological models are (roughly speaking) equivalent with respect to the class of objects which can be modelled (i.e. with respect to dimension and orientability).     

The living in a lattice rule language

This paper presents a rule-based query language for an object-oriented database model. The database model supports complex objects, object identity, classes and types, and a class/type hierarchy. The instances are described by ‘object relations’ which are functions from a set of objects to value sets and other object sets. The rule language is based on object-terms which provide access to objects via the class hierarchy. Rules are divided into two classes: object-preserving rules manipulating existing objects (yielding a new ‘view’ on objects available in the object base) and object-generating rules creating new objects with properties derived from existing objects. The derived object sets are included in a class lattice. We give conditions for whether the instances of the ‘rules’ heads are ‘consistent’, i.e. represent object relations where the properties of the derived objects are functionally determined by the objects.     

A silicon pressure sensor with a low-cost contactless interferometric optical readout

A novel miniature pressure sensor based on a silicon micromembrane with non-electric contactless readout of its deflection by low-cost integrated interferometric optical means (a simple ‘white’-light source and a special single-chip photodetector) has been elaborated. In contrast to the well-known piezoresistive or capacitive readout, the contactless optical approach will provide accurate measurements of absolute or differential pressure even in severe environments and at elevated temperatures. Preliminary experiments performed show the feasibility of such a sensor.     

An approach towards the design of intelligent man-machine interfaces used in process control

This paper is related to improvements carried out n the field of human-machine communication in complex industrial processes, using the concept of the ‘intelligent’ interface. Following a review of literature on this subject, an ‘intelligent’ interface design based on ergonomical concepts is described. Finally, we present our approach to the design of an ‘intelligent’ interface. The Decisional Module of Imagery (D.M.I.) as it is called, is based on two models: a task model and a user model. The D.M.I.'s structure and its integration in an experimental platform are described in the last part of this paper.     

A Large scale finite element analysis using domain decomposition method on a parallel computer

A parallel finite element analysis based on a domain decomposition technique (DDT) is considered. In the present DDT, an analysis domain is divided into a number of smaller subdomains without overlap. Finite element analyses of the subdomains are performed under the constraint of both displacement continuity and force equivalence among them. The constraint is satisfied through iterative calculations based on either the Uzawa algorithm or the Conjugate Gradient (CG) method. Owing to the iterative algorithm, a large scale finite element analysis can be divided into a number of smaller ones which can be carried out in parallel.

The DDT is implemented on a parallel computer network composed of a number of 32-bit microprocessors, transputers. The developed parallel calculation system named the ‘FEM server type system’ involves peculiar features such as network independence and dynamic workload balance.

The characteristics of the domain decomposition method such as computational speed and memory requirement are first examined in detail through the finite element calculations of homogeneous or inhomogeneous cracked plate subjected to a tensile load on a single CPU computer.

The ‘speedup’ and ‘performance’ features of the FEM server type system are discussed on a parallel computer system composed of up to 16 transputers, with changing network types and domain decompositions. It is clearly demonstrated that the present parallel computing system requires a much smaller amount of computational memory than the conventional finite element method and also that, due to the feature of dynamic workload balancing, high performance (over 90%) is achieved even in a large scale finite element calculation with irregular domain decomposition.     

On uncertainty versus size in branching programs

We propose an information-theoretic approach to proving lower bounds on the size of branching programs. The argument is based on Kraft type inequalities for the average amount of uncertainty about (or entropy of) a given input during the various stages of computation. The uncertainty is measured by the average depth of so-called ‘splitting trees’ for sets of inputs reaching particular nodes of the program.

We first demonstrate the approach for read-once branching programs. Then, we introduce a strictly larger class of so-called ‘balanced’ branching programs and, using the suggested approach, prove that some explicit Boolean functions cannot be computed by balanced programs of polynomial size. These lower bounds are new since some explicit functions, which are known to be hard for most previously considered restricted classes of branching programs, can be easily computed by balanced branching programs of polynomial size.     

Consumer-oriented versus technology-oriented systems: designing services for people

Current computer systems providing consumer services seem to be designed primarily on ‘technology-oriented’ thinking, based on the ‘efficiency’ and the operating methods of the computer. To be of benefit to a wider variety of consumers, the system design may have to reflect a more ‘consumer-oriented’ approach, based on factors such as the needs, preferences, skills and knowledge of the user. This article demonstrates the differences between user evaluations of two computer systems designed to help in house-hunting, modelled on (a) consumer-oriented, and (b) technology-oriented approaches. Although particularly relevant to consumer systems, the article may have important implications for consumer and public services in general.     

New horizontal frustum optical waveguide fabrication using UV proximity printing

This paper presents a novel method for fabricating the horizontal frustum structure as a planar optical waveguide using the proximity printing technique. A horizontal frustum optical waveguide with both lateral and vertical taper structure was produced. The orthogonal and inclined masks with the diffraction effect were employed in the lithography process. This method can precisely control each horizontal frustum optical waveguide geometric profile in the fabrication process. The horizontal frustum optical waveguide and its array with the same inclined angle were generated. The beam propagation simulation software (BPM_CAD) was used to model the optical performance. The simulation results reveal that the mode profile matched into horizontal frustum optical waveguide and fiber from the laser diode. The optical loss of the horizontal hemi-frustum optical waveguide structure was less than 0.2 dB. The horizontal hemi-frustum waveguide will be used for fiber coupling on boards for future optical communication systems.     

The constituents of business interaction––generic layered patterns

In order to perform business modelling as apart of information systems development, there is a need for frameworks and methods. The paper proposes a framework for business interaction based on a language/action perspective. The framework is an architecture of five generic layers. The first layer concept is ‘business act’, which functions as the basic unit of analysis. The following four layer concepts are ‘action pair’, ‘exchange’, ‘business transaction’, and ‘transaction group’. The framework is inspired by a similar framework constructed by Weigand et al. The paper makes a critical examination of this framework as a basis for the proposed framework.     

A comparison of software-based techniques intended to increase the reliability of embedded applications in the presence of EMI

Corruption of the instruction pointer in an embedded computer system has been shown to be a common failure mode in the presence of electromagnetic interference, and previous investigators have suggested that the use of techniques such as ‘Function Tokens’ (FT) and ‘NOP Fills’ (NF) can reduce the impact of such failures. In this paper, both a statistical analysis and empirical tests of code from an embedded application are used to assess and compare these techniques. Two main results are presented. First, it is demonstrated that claims about the effectiveness of FT may neither be well founded nor generally applicable; specifically, it is concluded that rather than increasing system reliability, the use of FT will have the opposite effect. Second, it is demonstrated that NF may be easily applied in most embedded applications, and that the use of this approach can have a positive impact on system reliability.     

Knowledge-based analysis of carotid angiograms

The project described is concerned with the development of a practical system for interpreting carotid angiograms. The general requirements of such a system are identified and some of the design considerations are discussed. The analysis strategies and types of knowledge used by an expert in recognizing and naming vessels and categorizing abnormalities on a single-plane angiogram are described- Two distinct types of knowledge are identified: ‘facts’ knowledge which is drawn from various areas of science, and ‘strategy’ knowledge which determines how the facts should be used. It is suggested that confidence parameters should be associated with each type of knowledge and these should be used in the control of the analysis of an angiogram. The ‘facts’ and ‘strategy’ knowledge bases have a hierarchical structure which, if exploited, would enable the system to be easily adapted for use in other application areas.     

Comments on: ‘Diagonal dominance for multivariable Nyquist array methods using function minimization’

The above paper (Leininger, 1979) claims to give a ‘new’ method for achieving diagonal dominance in multivariable systems. This is, however, not the first time that a function minimization approach has been used to obtain dominance. An optimisation oriented method was first proposed in 1975 (Ahson, 1975). This method is based on a new formulation of diagonal dominance criterion which takes into account model parameter uncertainties.     

Getting to know each other—Artificial social intelligence for autonomous robots

This paper proposes a research direction to study the development of ‘artificial social intelligence’ of autonomous robots which should result in ‘individualized robot societies’. The approach is highly inspired by the ‘social intelligence hypothesis’, derived from the investigation of primate societies, suggesting that primate intelligence originally evolved to solve social problems and was only later extended to problems outside the social domain. We suggest that it might be a general principle in the evolution of intelligence, applicable to both natural and artificial systems. Arguments are presented why the investigation of social intelligence for artifacts is not only an interesting research issue for the study of biological principles, but may be a necessary prerequisite for those scenarios in which autonomous robots are integrated into human societies, interacting and communicating both with humans and with each other. As a starting point to study experimentally the development of robots' ‘social relationships’, the investigation of collection and use of body images by means of imitation is proposed. A specific experimental setup which we use to test the theoretical considerations is described. The paper outlines in what kind of applications and for what kind of robot group structures social intelligence might be advantageous.     

Defining a taxonomy of output modalities from an HCI perspective

The paper addresses an issue that must be resolved to produce a scientifically sound and practically useful reference model for intelligent multimedia presentation systems (IMP systems), namely that of providing, from the point of view of Human-Computer Interaction (HCI), a systematic understanding of the types of output information to be presented by IMP systems. The term ‘medium’, as it is used in the context of multimedia systems, is too coarse-grained for distinguishing between different types of output information. The paper introduces the notion of (representational) ‘modalities’ to enable sufficiently fine-grained distinctions to be made. For the term itself to be meaningful, ‘multimodal’ presentations must be composed of unimodal representations. In the approach presented, unimodal representations are defined from a small number of basic properties whose combinations specify the ‘generic’ level of a taxonomy of unimodal output modalities. Additional basic property distinctions serve to generate the more fine-grained ‘atomic’ and ‘sub-atomic’ levels in a hierarchical fashion. The taxonomy is set up with the aim of satisfying four basic requirements, viz. completeness, orthogonality, relevance and intuitiveness. A concluding discussion illustrates the practical use of the taxonomy.     

Optimal measurement trajectories for distributed parameter systems

The paper deals with the optimal sensor location problem associated with minimax filtering for linear distributed parameter systems under the moving sensors. The problem of optimal choice of a measurement trajectory is treated here as an H^∞-optimal control one under phase constraints with the objective to minimize a given ‘weak’ performance index under ‘worst’ possible disturbances. Existence of a solution to such a problem is established for the case of quadratic constraints on the disturbances and necessary conditions for optimally are derived on the basis of constructing a sequence of suboptimal solutions associated, in turn, with a sequence of finite-dimensional maximum principles.     

Exact one-way methods for acoustic waveguides

Exact one-way re-formulations of the Helmholtz equation are useful for waveguide problems, since the resulting equations can be efficiently solved as ‘initial’ value problems by range marching methods. Some numerical methods for these re-formulations are reviewed in this paper. This includes a switched method that avoids the singularities of the operators and the large range step methods that give exact solutions for range independent regions and allow large range steps for weakly range dependent regions. For waveguides with curved bottoms, a method based on a local orthogonal transformation is described. As an interesting application, the scattering problem of periodic waveguides is considered.     

Heuristic approach to allocation of trucks in a transportation system

This paper considers the problem of how luggages should be assign to each truck for the transportation system consists of a depot, a fixed area and two types of luggages, called schedule problem. The main purpose of this paper is to propose a procedure for the problem subject to keep the balance of work loads among truck drivers. The procedure is based on 3 (heuristic) rules for replacing the addresses of each luggage with the ‘conventional address,’ converting size of each luggage into ‘weight’ and introducing a measure to keep the balance of work loads. The procedure consists of three stages according to ‘priority’ of the types of luggages. A case study is presented that demonstrate the practical usefulness of the procedure.     

Test feature selection for a complex electro-hydraulic servo system using frequency response measurements

A technique for the selection of the best set of test features for checkout or go-no-go test of a complex electro-hydraulic servo system from input-output measurements is presented. The first step is to establish checkout tolerance bands on the system response. Then the measurement set based on gain and phase which would best discriminate between the ‘healthy’ and ‘sick’ systems is selected from an initially large set of sampled frequencies via an optimization procedure in which the feature efficiency vector is introduced to add or discard features until a satisfactory set is obtained. Finally the selected feature sets are assessed for effectiveness via a ‘goodness’ criterion.     

Boundary matching algorithm for connected component labelling using linear quadtrees

A computationally fast top-down recursive algorithm for connected component labelling using linear quadtrees is presented. The input data structure used is a linear quadtree representing only black leaf nodes. The boundary matching approach used ensures that at most two adjacencies of any black leaf node are considered. Neighbour searching is carried out within restricted subsets of the input quadtree. The time and space complexities of the algorithm are O(Bn) and O(B) respectively for a linear quadtree with B black leaves constructed from a binary array of size 2ⁿ × 2ⁿ. Simulations show the algorithm to be twice as fast as an existing algorithm that uses an identical input data structure. The top-down algorithm presented can also be used to efficiently generate a linear quadtree representing all nodes — ‘grey’, ‘black’ and ‘white’ — in preorder when given an input linear quadtree representing only ‘black’ leaf nodes. The boundary matching algorithm is computationally fast and has low static and dynamic storage costs, making it useful for applications where linear quadtrees are held in main memory.