Automatic Decomposition Research Articles

Preprocessing for 2D FE-BE domain decomposition methods

The non-overlapping Domain Decomposition (DD) method is a powerful tool for the coupling of Finite Element (FE) and Boundary Element (BE) methods. Moreover it provides a natural basis for constructing efficient parallel solvers. However, both, the efficiency and the robustness of DD–solvers depends heavily on the underlying decomposition of the domain of interest into subdomains. In this paper, we introduce the Adaptive Domain Decomposition Preprocessor ADDPre which realizes an automatic decomposition of the computational domain into p subdomains, where p is the number of processors to be used. We discuss the codes being involved, the algorithms which they are based on and the data–formats being used for describing the decomposition of the problem. Numerical examples, demonstrating the performance of the preprocessor are presented.

Automated conceptual design of mechanisms

Traditionally, the conceptual design of mechanisms was an art, based primarily on the experience of the designer. Today, despite the great advances in the science of machine systems, mechanism design is still a mixture of art and science. The basic premise behind this research was that experienced designers create complex mechanisms, in part, by concocting abstract representations of simpler building blocks. We made attempts to identify a finite set of design building blocks and to represent them in a manner that enables a rational, and therefore a computable, scheme for creation of mechanisms. Based on a systematic investigation of hundreds of existing mechanisms and machines, we first identified a finite set of kinematic building blocks. We then devised a matrix representation scheme that not only captures the essential nature of the building blocks, but also enables automatic decomposition of a given task into simpler sub-tasks. The matrix representation scheme served as a formal means to: (a) represent and reason with the building blocks at different levels of abstraction, (b) generate alternate conceptual designs, and (c) facilitate rapid simulation of design concepts by readily connecting a series of building blocks. The synthesis methodology based on the matrix representation was successfully implemented in a computer program for design of function generating mechanisms. The program takes as input the user supplied specification of input/output motion requirements and constraints, and automatically generates alternate conceptual designs. The matrix representation method and the automated design procedure are described in this paper, along with a design example.

Automatic Block Decomposition of Parametrically Changing Volumes

A method is introduced for the automatic decomposition of time-varying volumes such as those encountered in engine FEA and CFD. Examples of the application of this method to all-hexahedral mesh generation are also presented.

Bewegungsanalyse für die objektbasierte Video-Codierung

An essential stage for the implementation of object-based video coding techniques is the automatic decomposition of an image sequence into different moving objects. The presented technique for motion segmentation is based on the concept of affine motion hypotheses. In an inital stage a set of motion hypotheses is generated for a given group of images. The segmentation of the group of images is obtained by classifying each image location to one of the extracted motion hypotheses. The iterative nature of the algorithm results in an alternative refinement of the object boundaries and the motion parameters. The extracted objects are characterized by their boundaries and a set of motion parameters. During the segmentation process an additionally depth parameter is assigned to each object Thus occlusion areas and uncovered regions can be predicted on tire basis of the object boundaries in the first image of the group.

Coupling of the Boltzmann and Euler Equations with Automatic Domain Decomposition

A criterion for automatic domain decomposition has been introduced for the coupling of the Boltzmann and Euler equations. This criterion is obtained by using the Grad's 13-moments expansion method. The Boltzmann and Euler equations have been solved by the particle method. This criterion has been further tested for the spatial homogeneous relaxation case and the coupling of the Boltzmann and Euler equations in two dimensional physical space. Some numerical results obtained from the particle code of the full Boltzmann equation are compared with those of coupling of the Boltzmann and Euler equations.

Development of an intelligent task management system in a manufacturing information network

Recent research related to agent-based systems has seen significant advances made in terms of the `intelligence' level of collaborative and autonomous features of agents with a number of proposed frameworks reported in contemporary publications. However, the automatic decomposition of job requests into basic tasks to be carried out by relevant agents, which enhances the `intelligence' level of the system, has not received as much attention as it deserves. This article presents an Intelligent Task Management System (ITMS) which can usefully be deployed in a manufacturing information network. It comprises a rule-based inference mechanism responsible for the division of a client's job request into basic tasks and an Object-Oriented Virtual Agent (OOVA) module created using object-oriented technology for achieving automatic task decomposition and assignment. The prototype program of this ITMS has been developed and then tested in an emulated manufacturing environment, using CLIPS as the tool for building the rule-based program and Visual Basic 5 for constructing the OOVA module. It is expected that the experience of developing and implementing the ITMS may be useful for the design of the next generation of collaborative agent-based systems to be adopted in a manufacturing information network. In this article, details related to the structure, design and implementation of the ITMS are covered with actual program codes included. Further, a methodology for the design of the Rule-based Inference Mechanism (RIM) is also presented.

Automatic multiblock decomposition using hypercube++ for grid generation

A new method for an automatic multiblock decomposition of a field around any number of complex geometries is proposed. This method is based on hypercube++ data structure to represent the hierarchical relationship between various types of hypercubes while the geometry of the hypercube is represented by non-uniform rational B-splines (NURBS) volume which maps the physical space of a hypercube onto the parameter space. The generation of grid topology based on the hypercube++ structure consists of two main steps: (1) the hypercube++ generation step, which is applied to the region around a single shape element, for example a wing in an airplane, to generate an appropriate hypercube; and (2) the hypercube++ merging step, which merges simple hypercubes or the ones merged already into a single but more complex hypercube++ to represent the regions around the shape composed of several shape elements. This approach will be demonstrated with some examples to show that it allows a user to construct a multiblock decomposition in a matter of minutes for any three dimensional configurations in an automatic manner.

Conversion of a single process CFD code to distributed and massively parallel processing

An existing computational fluid dynamics (CFD) computer code was converted from a single process execution mode to one employing both massively parallel processing (MPP) on an nCUBE MPP computer using the native nCUBE message passing application programmers interface (API) and distributed processing (DP) on a cluster of workstations using the Parallel Virtual Machine (PVM) API for message passing. Specifications for the conversion included the ability to easily incorporate new message passing API's, automatic decomposition and distribution of a problem to the different processors, direct node to node communication, and the same user interface as in the single process mode. There was also a strong desire to have a single code which could be compiled to run in any programmed message passing API, in the multitasking parallel processing mode already in the code, and in single process mode. These criteria produced a single code which eliminates the concern associated with maintaining multiple versions of a code, provides efficient communication, and minimizes the learning curve for users not conversant with the mechanics of distributed processing.

ESO & NOT photometric monitoring of the Cloverleaf quasar

The Cloverleaf quasar, H1413+117, has been photometrically monitored at ESO (La Silla, Chile) and with the NOT (La Palma, Spain) during the period 1987-1994. All good quality CCD frames have been successfully analysed using two independent methods (i.e. an automatic image decomposition technique and an interactive CLEAN algorithm). The photometric results from the two methods are found to be very similar, and they show that the four lensed QSO images vary significantly in brightness (by up to 0.45 mag), nearly in parallel. The lightcurve of the D component presents some slight departures from the general trend which are very likely caused by micro-lensing effects. Upper limits, at the 99% confidence level, of 150 days on the absolute value for the time delays between the photometric lightcurves of this quadruply imaged variable QSO, are derived. This is unfortunately too large to constrain the lens model but there is little doubt that a better sampling of the lightcurves should allow to accurately derive these time delays. Pending a direct detection of the lensing galaxy (position and redshift), this system thus constitutes another good candidate for a direct and independent determination of the Hubble parameter.

Automatic control of a One-of-a-Kind Production cell

This paper reports the outcome of a research project which aims to solve the problems in automatic control of the shop floor in One-of-a-Kind Production (OKP) through developing a prototype control system for an experimental OKP cell at the laboratory. The main problems in automatic control of the shop floor in OKP are the frequent changes of product structure or type and consequent changes of production system configuration. These changes in OKP make it necessary to have a highly flexible and robust automatic control system. To resolve the problems, a distributed control system has been developed at the CIM laboratory of the Department of Production, Aalborg University, Denmark. This control system has enough flexibility and robustness to cope with the aforementioned changes in OKP. To support the design and implementation of the control system, several concepts, algorithms and control principles, such as task logic routes, address code of production resources, automatic task decomposition algorithm, generic control modules and distributed control principles are also proposed in this paper.

Automatic state space decomposition for approximate FSM traversal based on circuit analysis

Exploiting circuit structure is a key issue in the implementation of algorithms for state space decomposition when the target is approximate FSM traversal. Given the gate-level description of a sequential circuit, the information about its structure can be captured by evaluating the affinity between pairs or groups of latches. Two main factors have to be considered in carrying out the structural analysis of a sequential circuit: latch connectivity and latch correlation. The first one takes into account the mutual dependency of each memory element on the others; the second one tells us how related are the functions realized by the logic feeding each latch. In this paper we estimate the affinity of two latches by combining these two factors, and we use this measure to formulate the state space decomposition problem as a graph partitioning problem. We propose an algorithm to automatically determine good partitions of the latch set which induce state space decomposition, and we present approximate FSM traversal and logic optimization results for the largest ISCAS'89 sequential benchmarks.

AUTOMATIC DATA AND COMPUTATION DECOMPOSITION FOR DISTRIBUTED-MEMORY MACHINES

In this paper, we develop an automatic compile-time computation and data decomposition technique for distributed-memory machines. Our method handles complex programs containing perfect and non-perfect loop nests with or without loop-carried dependences. Applying our algorithms, a program will be divided into collections (called clusters) of loop nests, such that data redistributions are allowed only between the clusters. Within each cluster of loop nests, decomposition and data locality constraints are formulated as a system of homogeneous linear equations which is solved by polynomial time algorithms. Our algorithm can selectively relax data locality constraints within a cluster to achieve a balance between parallelism and data locality. Such relaxations are guided by exploiting the hierarchical program nesting structures from outer to inner nesting levels to keep the communications at a outer-most level possible.

Effects of temperature on motor unit action potentials during isometric contraction.

The effect of temperature on motor unit action potential (MUAP) configuration and recruitment was studied using automatic decomposition electromyography (ADEMG) recordings from a concentric needle electrode placed in the first dorsal interosseous (FDI) muscle of 10 normal adult subjects during isometric contraction. Focally cooling the FDI resulted in prolonged MUAP duration (P < 0.001, ANOVA), a finding congruent with those of Buchthal. Focal ulnar cooling at the elbow resulted in the increased MUAP frequency. In contrast to previous studies, there were no significant differences in amplitude or turns. Greater understanding of normal motor unit electrophysiology is necessary to improve diagnostic accuracy of EMG testing.

Multi‐motor unit action potential analysis (MMA)

We have developed an algorithm, called multi-motor unit action potential analysis (MMA), to aid quantification in routine needle EMG examination. In only 5-8 min, it was possible to extract, analyze, and validate 20 motor unit action potentials (MUAPs). In the biceps muscle of normal subjects, the MUAP measurements are compared with measurements using manual, triggered averaging, automatic decomposition, and other MMA algorithms described in the literature. The mean values of MUAP features by MMA fell between the extreme limits obtained from the amplitude-triggered method and the manual method described in the literature. In patients, the results are consistent with routine EMG and similar to those results described in the literature. Fast acquisition and analysis of MUAPs as well as interference pattern (IP) analysis make this technique useful to document EMG abnormalities in routine needle examination.

Novel approach to contiguous band multiplexer design for satellite applications

AbstractA novel and general technique for the optimization of contiguous band multiplexers using sensitivity analysis is presented. The method utilizes exact partial derivatives of circuit responses with respect to all design parameters. The equivalent circuit includes channel filters, waveguide spacings, and three‐port waveguide junctions. A 12‐channel contiguous multiplexer at Ku band has been designed. Utilization of an efficient modelization and automatic decomposition approaches resulted in an excellent simulation performance of the presented multiplexer.

Automatic decomposition electromyography in idiopathic inflammatory myopathies.

Automatic decomposition electromyography (ADEMG) is a commercially available software package with installed reference values that enables the objective measurement of motor unit action potentials (MUAPs). To assess the diagnostic yield of this package in idiopathic inflammatory myopathies (IIM) we performed bicepts brachii ADEMG in 17 patients with polymyositis, dermatomyositis and inclusion body myositis. Results were compared with those in 12 controls, and with the results of conventional EMG of the biceps and other muscles. Decreased mean values for MUAP duration occurred significantly more frequently in IIM patients than in controls; other MUAP characteristics did not differ. In IIM patients, decreased mean amplitude and increased mean number of turns occurred significantly less frequently on ADEMG than did corresponding abnormalities on conventional biceps EMG. Decreased mean values for duration and amplitude, and increased mean values for number of turns were seen significantly less often on ADEMG than corresponding abnormalities on conventional EMG of four different, individually chosen muscles. Overall evaluation of ADEMG resulted in a diagnosis of "possible myopathy" in 1 and "probable myopathy" in 8 patients, whereas overall evaluation of conventional EMG led to a diagnosis "suggestive of IIM" in 13 patients. We conclude that, although measurement of mean MUAP duration might be valuable in IIM diagnosis, our results do not favour the use of biceps brachii ADEMG and the installed reference values for the diagnosis of IIM. We suggest modifications to improve ADEMG's applicability.

Optimal design of contiguous band multiplexers

An optimisation technique as well as a sensitivity analysis for multiplexing networks are presented. The method uses exact partial derivatives of circuit responses with respect to all design parameters. The equivalent circuit includes channel filters, waveguide spacings and a three-port waveguide junction.A 12 channel contiguous multiplexer at Ku band has been designed. Use of an efficient model and automatic decomposition approaches resulted in an excellent simulation performance of the presented multiplexer.

Structural safety analysis of fixed offshore platforms

The objective of this paper is to discuss the structural safety analysis of large framed offshore structures on distributed memory parallel computers. It involves: automatic FEM domain decomposition, sparse multifrontal method, elastic-plastic incremental analysis with strain-hardening and large displacements effects and reliability analysis procedures. An application is presented to illustrate the strategy potentialities on the Intel iPSC/860 hypercube.

Finite difference approximations for the three-dimensional Laplacian in irregular grids

Two numerical approximations of the three-dimensional Laplacian Operator at a point are each obtained in a form which is suitable for computation at nodes generated in an automatic decomposition of an arbitrary three-dimensional region. The first expression is derived by an extension of a technique previously developed for two-dimensional configurations and is shown to generalise the well known Cartesian form. The second approximation, which assumes a linear dependence of the scalar field on certain nodal values of this field, and for which a variational justification is established, also reduces to the Cartesian form for a particular arrangement of surrounding nodes.

Quantitative electromyographic analysis of the external urethral sphincter using automatic decomposition electromyography on normal subjects

Motor unit action potentials (MUPs) of the external urethral sphincter muscle during cystometry were analysed on six normal males. Electrodes were of concentric needle type having the exposed tip surface of 0.07 mm2, and the potential changes were analysed by automatic decomposition electromyography (ADEMG), for isolation and characterization of unit discharges. Number of analysed units was as follows: Two at rest, 4 at first desire to void, and 6 at maximum desire to void. Number of the recorded units and the firing rate were increased along with the degree of bladder filling. Average MUP figures as follows: Amplitude of 206 microV, 8.3 msec. duration, and 5.4 Hz firing rate at rest; 246 microV, 9.7 msec and 7.3 Hz at first desire to void; 277 microV. 9.7 msec and 7.2 Hz at maximum desire to void, respectively. It is concluded that external urethral sphincter maintains its urinary continence by excitation of the neuromuscular units, and by the increase in the firing rate of individual MUP during bladder filling.