			Home About us Contact

Complex Domain (complex + domain)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

LayTracks: a new approach to automated geometry adaptive quadrilateral mesh generation using medial axis transform

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2004
W. R. Quadros
Abstract A new mesh generation algorithm called ,LayTracks', to automatically generate an all quad mesh that is adapted to the variation of geometric feature size in the domain is described. LayTracks combines the merits of two popular direct techniques for quadrilateral mesh generation,quad meshing by decomposition and advancing front quad meshing. While the MAT has been used for the domain decomposition before, this is the first attempt to use the MAT, for the robust subdivision of a complex domain into a well defined sub-domain called ,Tracks', for terminating the advancing front of the mesh elements without complex interference checks and to use radius function for providing sizing function for adaptive meshing. The process of subdivision of a domain is analogous to, formation of railway tracks by laying rails on the ground. Each rail starts from a node on the boundary and propagates towards the medial axis (MA) and then from the MA towards the boundary. Quadrilateral elements are then obtained by placing nodes on these rails and connecting them inside each track, formed by adjacent rails. The algorithm has been implemented and tested on some typical geometries and the quality of the output mesh obtained are presented. Extension of this technique to all hexahedral meshing is discussed. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Isaac M. Horowitz: an essential singularity in the complex domain of control theory (1920,2005)

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2-3 2007
Deputy Dean, Eduard Eitelberg Professor
First page of article [source]

Purification and expression of a protein elicitor from Alternaria tenuissima and elicitor-mediated defence responses in tobacco

ANNALS OF APPLIED BIOLOGY, Issue 3 2010
J. Mao
A new protein elicitor, PeaT1, was purified from the mycelium of Alternaria tenuissima by column chromatography. PeaT1 was identified as a heat-stable and acidic protein. It induced systemic acquired resistance to tobacco mosaic virus (TMV) in tobacco plants but did not cause hypersensitive response. The elicitor-encoding gene was cloned by rapid amplification of cDNA ends method. Sequence analysis revealed that the cDNA is 624 bp in length and the open reading frame encodes for a polypeptide of 207 amino acids with a nascent polypeptide-associated complex domain. The peaT1 gene was cloned into the expression vector pET-28a and transformed into Escherichia coli BL21 (DE3). The recombinant elicitor also triggered defence responses in intact tobacco plants. The availability of the pure protein offers the possibility to isolate the corresponding receptor and links it to the downstream signalling pathway. [source]

Knowledge-based system for structured examination, diagnosis and therapy in treatment of traumatised teeth

DENTAL TRAUMATOLOGY, Issue 1 2001
A. Robertson
Abstract , Dental trauma in children and adolescents is a common problem, and the prevalence of these injuries has increased in the last 10,20 years. A dental injury should always be considered an emergency and, thus, be treated immediately to relieve pain, facilitate reduction of displaced teeth, reconstruct lost hard tissue, and improve prognosis. Rational therapy depends upon a correct diagnosis, which can be achieved with the aid of various examination techniques. It must be understood that an incomplete examination can lead to inaccurate diagnosis and less successful treatment. Good knowledge of traumatology and models of treatments can also reduce stress and anxiety for both the patient and the dental team. Knowledge-based Systems (KBS) are a practical implementation of Artificial Intelligence. In complex domains which humans find difficult to understand, KBS can assist in making decisions and can also add knowledge. The aim of this paper is to describe the structure of a knowledge-based system for structured examination, diagnosis and therapy for traumatised primary and permanent teeth. A commercially available program was used as developmental tool for the programming (XpertRule, Attar, London, UK). The paper presents a model for a computerised decision support system for traumatology. [source]

Polygonal finite elements for topology optimization: A unifying paradigm

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2010
Cameron Talischi
Abstract In topology optimization literature, the parameterization of design is commonly carried out on uniform grids consisting of Lagrangian-type finite elements (e.g. linear quads). These formulations, however, suffer from numerical anomalies such as checkerboard patterns and one-node connections, which has prompted extensive research on these topics. A problem less often noted is that the constrained geometry of these discretizations can cause bias in the orientation of members, leading to mesh-dependent sub-optimal designs. Thus, to address the geometric features of the spatial discretization, we examine the use of unstructured meshes in reducing the influence of mesh geometry on topology optimization solutions. More specifically, we consider polygonal meshes constructed from Voronoi tessellations, which in addition to possessing higher degree of geometric isotropy, allow for greater flexibility in discretizing complex domains without suffering from numerical instabilities. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Electrifying diagrams for learning: principles for complex representational systems

COGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 6 2002
Peter C.-H.
Abstract Six characteristics of effective representational systems for conceptual learning in complex domains have been identified. Such representations should: (1) integrate levels of abstraction; (2) combine globally homogeneous with locally heterogeneous representation of concepts; (3) integrate alternative perspectives of the domain; (4) support malleable manipulation of expressions; (5) possess compact procedures; and (6) have uniform procedures. The characteristics were discovered by analysing and evaluating a novel diagrammatic representation that has been invented to support students' comprehension of electricity,AVOW diagrams (Amps, Volts, Ohms, Watts). A task analysis is presented that demonstrates that problem solving using a conventional algebraic approach demands more effort than AVOW diagrams. In an experiment comparing two groups of learners using the alternative approaches, the group using AVOW diagrams learned more than the group using equations and were better able to solve complex transfer problems and questions involving multiple constraints. Analysis of verbal protocols and work scratchings showed that the AVOW diagram group, in contrast to the equations group, acquired a coherently organised network of concepts, learnt effective problem solving procedures, and experienced more positive learning events. The six principles of effective representations were proposed on the basis of these findings. AVOW diagrams are Law Encoding Diagrams, a general class of representations that have been shown to support learning in other scientific domains. [source]