Cumincad : CUMINCAD Papers : Search Results

CumInCAD is a Cumulative Index about publications in Computer Aided Architectural Design
supported by the sibling associations ACADIA, CAADRIA, eCAADe, SIGraDi, ASCAAD and CAAD futures

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_id	c6e3
authors	Kirsch, Uri
year	1982
title	Approximation Concepts for Optimum Structural Design
source	25 p. Pittsburgh, PA: Design Research Center, CMU, December, 1982. DRC-12-12-82. includes bibliography
summary	When elastic behavior is assumed, the optimum structural design problem is stated in an implicit nonlinear programming form. Approximate behavior models are introduced to obtain explicit constraint functions, essential in many practical design problems. For the displacement analysis formulation, some possible explicit approximations of the nodal displacements in terms of the design variables are reviewed. It is shown that any approximation of the displacements will lead to a solution which does not necessarily satisfy equilibrium. Methods for solving the approximate problem are discussed. Using the force analysis formulation, it is shown that explicit approximations of the redundant forces will lead to solutions which do not necessarily satisfy compatibility. Some simplified models of the explicit problem are presented and solution methods are discussed
keywords	structures, design, engineering, optimization, civil engineering, approximation
series	CADline
last changed	1999/02/12 15:08

_id	2786
authors	Woodwark, J.R.
year	1989
title	Splitting Set-Theoretic Solid Models into Connected Components
source	10 p. : ill. Winchester: IBM UK Scientific Center, IBM United Kingdom Laboratories Limited, June, 1989. IBM UKSC 210. includes bibliography In general, there is no way to tell how many pieces (connected components) a set-theoretic (CSG) solid model represents, except via conversion to a boundary model. Recent work on the elimination of redundant primitives has been linked with techniques for identifying connected components in quad-trees and oct-trees into a strategy to attack this problem. Some success has been achieved, and an experimental Prolog program, working in two dimensions, that finds connected components and determines the set-theoretic representation of each component, is reported, and further developments proposed. CSG / quadtree / octree / primitives / algorithms. 43. Woodwark, J. R. and Quinlan K. M. 'Reducing the Effect of Complexity on Volume Model Evaluation.' Computer Aided Design. April, 1982. pp. 89-95 : ill. includes bibliography.
summary	A major problem with volume modelling systems is that processing times may increase with model complexity in a worse than linear fashion. The authors have addressed this problem, for picture generation, by repeatedly dividing the space occupied by a model, and evaluating the sub-models created only when they meet a criterion of simplicity. Hidden surface elimination has been integrated with evaluation, in such a way that major portions of the model which are not visible are never evaluated. An example demonstrates a better than linear relationship between model complexity and computation time, and also shows the effect of picture complexity on the performance of the process
keywords	CAD, computational geometry, solid modeling, geometric modeling, algorithms, hidden surfaces, CSG
series	CADline
last changed	2003/06/02 13:58

_id	6094
authors	Blinn, J.I.
year	1982
title	A Generalization of Algebraic Surface Drawing
source	ACM Transaction on Graphics, vol. 1, no. 3, pp. 235-256, 1982
summary	The technology of creating realistic and visually interesting images of three- dimensional shapes is advancing on many fronts. One such front is the develop- ment of algorithms for drawing curved surfaces directly from their mathematical definitions rather than by dividing them into large numbers of polygons. Two classes of surfaces which have received attention are the quadric and the bivariate parametric surfaces. Bivariate parametric surfaces are generated by three func- tions of two variables (most popularly polynomials), as the variables take on different values. Algorithms dealing with such surfaces are due to Catmull; Lane, Carpenter, Whitted and Blinn; and Clark.
series	journal paper
last changed	2003/11/21 15:16

_id	09f3
authors	Burt, Michael, Kent, Eli and Ne'eman, Eliyahu (et al)
year	1982
title	Single- and Multilayer Large-Span Membrane Structures for Daylight, Energy Control, and Savings
source	1982? PP. 177-183 : ill. includes bibliography
summary	This paper examines membrane-covered structures. Such structures offer many advantages and their cost of construction is lower than that of equivalent alternatives. However, these thin, single-layer membrane covers cannot provide the control of daylight and heat required to make them environmentally satisfactory and energy-efficient. To improve the performance of membrane covers, a new solution has been studied. Double-layer membranes can be built without severe technical difficulties and provide a much higher degree of static and dynamic control. Further work is being carried out to study the option of incorporating into the two layer membrane structures solar collectors between the layers, thus converting the large area of the membrane cover into an active solar system
keywords	lighting, energy, analysis, topology, structures, building
series	CADline
last changed	2003/06/02 10:24

_id	c1bf
authors	Gouraud, H.
year	1982
title	Continuous shading of curved surfaces
source	IEEE Transactions on Computers, 20, no. 6, 623-629
summary	A procedure for computing shaded pictures of curved surfaces is presented. The surface is approximated by small polygons in order to solve easily the hidden-parts problem, but the shading of each polygon is computed so that the discontinuities of shade are eliminated across the surface and a smooth appearance is obtained. In order to achieve speed efficiency, the technique developed by Watkins is used which makes possible a hardware implementation of this algorithm.
series	journal paper
last changed	2003/04/23 15:14

_id	cf2011_p027
id	cf2011_p027
authors	Herssens, Jasmien; Heylighen Ann
year	2011
title	A Framework of Haptic Design Parameters for Architects: Sensory Paradox Between Content and Representation
source	Computer Aided Architectural Design Futures 2011 [Proceedings of the 14th International Conference on Computer Aided Architectural Design Futures / ISBN 9782874561429] Liege (Belgium) 4-8 July 2011, pp. 685-700.
summary	Architects‚Äîlike other designers‚Äîtend to think, know and work in a visual way. In design research, this way of knowing and working is highly valued as paramount to design expertise (Cross 1982, 2006). In case of architecture, however, it is not only a particular strength, but may as well be regarded as a serious weakness. The absence of non-visual features in traditional architectural spatial representations indicates how these are disregarded as important elements in conceiving space (Dischinger 2006). This bias towards vision, and the suppression of other senses‚Äîin the way architecture is conceived, taught and critiqued‚Äîresults in a disappearance of sensory qualities (Pallasmaa 2005). Nevertheless, if architects design with more attention to non visual senses, they are able to contribute to more inclusive environments. Indeed if an environment offers a range of sensory triggers, people with different sensory capacities are able to navigate and enjoy it. Rather than implementing as many sensory triggers as possible, the intention is to make buildings and spaces accessible and enjoyable for more people, in line with the objective of inclusive design (Clarkson et al. 2007), also called Design for All or Universal Design (Ostroff 2001). Within this overall objective, the aim of our study is to develop haptic design parameters that support architects during design in paying more attention to the role of haptics, i.e. the sense of touch, in the built environment by informing them about the haptic implications of their design decisions. In the context of our study, haptic design parameters are defined as variables that can be decided upon by designers throughout the design process, and the value of which determines the haptic characteristics of the resulting design. These characteristics are based on the expertise of people who are congenitally blind, as they are more attentive to non visual information, and of professional caregivers working with them. The parameters do not intend to be prescriptive, nor to impose a particular method. Instead they seek to facilitate a more inclusive design attitude by informing designers and helping them to think differently. As the insights from the empirical studies with people born blind and caregivers have been reported elsewhere (Authors 2010), this paper starts by outlining the haptic design parameters resulting from them. Following the classification of haptics into active, dynamic and passive touch, the built environment unfolds into surfaces that can act as ‚Äúmovement‚Äù, ‚Äúguiding‚Äù and/or ‚Äúrest‚Äù plane. Furthermore design techniques are suggested to check the haptic qualities during the design process. Subsequently, the paper reports on a focus group interview/workshop with professional architects to assess the usability of the haptic design parameters for design practice. The architects were then asked to try out the parameters in the context of a concrete design project. The reactions suggest that the participating architects immediately picked up the underlying idea of the parameters, and recognized their relevance in relation to the design project at stake, but that their representation confronts us with a sensory paradox: although the parameters question the impact of the visual in architectural design, they are meant to be used by designers, who are used to think, know and work in a visual way.
keywords	blindness, design parameters, haptics, inclusive design, vision
series	CAAD Futures
email
last changed	2012/02/11 19:21

_id	e323
authors	Holtz, Neal M. and Rasdorf, William J.
year	1982
title	The Use of LISP for Computer-Aided Design Systems
source	18, [19] p. Pittsburgh: Design Research Center, Carnegie-Mellon University, April, 1982. includes bibliography
summary	It is suggested that the LISP programming language has many advantages and few disadvantages for use in developing complex engineering application programs. The paper attempts to explore that possibility by briefly explaining a few of the concepts of the language, by discussing some of the criticisms of it, and by mentioning some new developments. In summary it is suggested that LISP may currently be the best programming language to use for the development of computer- aided design (CAD) systems
keywords	LISP, CAD, systems, programming, languages, CAE, engineering
series	CADline
last changed	2003/06/02 13:58

_id	8c27
authors	Kalay, Yehuda E.
year	1982
title	Determining the Spatial Containment of a Point in General Polyhedra
source	Computer graphics and Image Processing. 1982. vol. 19: pp. 303-334 : ill. includes bibliography. See also criticism and improvements in Orlowski, Marian
summary	Determining the inclusion of a point in volume-enclosing polyhedra (shapes) in 3D space is, in principle, the extension of the well-known problem of determining the inclusion of a point in a polygon in 2D space. However, the extra degree of freedom makes 3D point-polyhedron containment analysis much more difficult to solve than the 2D point polygon problem, mainly because of the nonsequential ordering of the shape elements, which requires global shape data to be applied for resolving special cases. Two general O(n) algorithms for solving the problem by reducing the 3D case into the solvable 2D case are presented. The first algorithm, denoted 'the projection method,' is applicable to any planar- faced polyhedron, reducing the dimensionality by employing parallel projection to generate planar images of the shape faces, together with an image of the point being tested for inclusion. The containment relationship of these images is used to increment a global parity-counter when appropriate, representing an abstraction for counting the intersections between the surface of the shape and a halfline extending from the point to infinity. An 'inside' relationship is established when the parity-count is odd. Special cases (coincidence of the halfline with edges or vertices of the shape) are resolved by eliminating the coincidental elements and re-projecting the merged faces. The second algorithm, denoted 'the intersection method,' is applicable to any well- formed shape, including curved-surfaced ones. It reduces the dimensionality by intersecting the polygonal trace of the shape surface at the plane of intersection, which is tested for containing the trace of the point in the plane, directly establishing the overall 3D containment relationship. A particular O(n) implementation of the 2D point-in-polygon inclusion algorithm, which is used for solving the problem once reduced in dimensionality, is also presented. The presentation is complemented by discussions of the problems associated with point-polyhedron relationship determination in general, and comparative analysis of the two particular algorithms presented
keywords	geometric modeling, point inclusion, polygons, polyhedra, computational geometry, algorithms, search, B-rep
series	CADline
email
last changed	2003/06/02 10:24

_id	2415
authors	Nievergelt, J. and Preparata, Franco P.
year	1982
title	Plane-Sweep Algorithms for Intersecting Geometric Figures
source	Communications of the ACM. October, 1982. vol. 25: pp. 739-747 : ill. includes bibliography
summary	Algorithms in computational geometry are of increasing importance in computer-aided design, for example, in the layout of integrated circuits. The efficient computation of the intersection of several superimposed figures is a basic problem. Plane figures defined by points connected by straight line segments are considered, for example, polygons (not necessarily simple) and maps (embedded planar graphs). The regions into which the plane is partitioned by these intersecting figures are to be processed in various ways such as listing the boundary of each region in cyclic order or sweeping the interior of each region. Let m be the total number of points of all the figures involved and s be the total number of intersections of all line segments. A two plane-sweep algorithm that solves the problems above is presented; in the general case (non convexity) in time O((n+s)log-n) and space O(n+s); when the regions of each given figure are convex, the same can be achieved in time O(n log n +s) and space O(n)
keywords	computational geometry, algorithms, intersection, mapping, polygons, data structures, analysis
series	CADline
last changed	2003/06/02 10:24

_id	2243
authors	O'Rourke, J., Chien, C.-B. and Olson, Th. (et al)
year	1982
title	A New Linear Algorithm for Intersecting Convex Polygons
source	Computer Graphics and Image Processing. 1982. vol. 19: pp. 384-391 : ill. includes a short bibliography
summary	An algorithm is presented that computes the intersection of two convex polygons in linear time. The algorithm is fundamentally different from the only known linear algorithms for this problem, due to Shamos and to Hoey. These algorithms depend on a division of the plane into either angular sectors (Shamos) or parallel slabs (Hoey), and are mildly complex. The authors' algorithm searches for the intersection points of the polygons by advancing a single pointer around each polygon, and is very easy to program
keywords	algorithms, boolean operations, polygons, intersection, search
series	CADline
last changed	2003/06/02 14:42

_id	233c
authors	Udupa, Jayaram K., Srihari, Sargur N. and Herman, Gabor T.
year	1982
title	Boundary Detection in Multidimensions
source	IEEE Transactions on Pattern Analysis and Machine Intelligence. January, 1982. vol. PAM-4: pp. 41-50 : ill. includes bibliography
summary	The development of image processing algorithms for time varying imagery and computerized tomography data calls for generalization of the concepts of adjacency, connectivity, boundary, etc. to three and four dimensional discrete spaces. This paper defines these basic concepts in unified terminology and presents algorithms for a boundary detection task in multidimensional space. The performance of these algorithms is discussed with respect to theoretical maximum complexity, and is illustrated with simulated computerized tomography data
keywords	algorithms, image processing, performance, applications
series	CADline
last changed	2003/06/02 13:58

_id	avocaad_2001_16
id	avocaad_2001_16
authors	Yu-Ying Chang, Yu-Tung Liu, Chien-Hui Wong
year	2001
title	Some Phenomena of Spatial Characteristics of Cyberspace
source	AVOCAAD - ADDED VALUE OF COMPUTER AIDED ARCHITECTURAL DESIGN, Nys Koenraad, Provoost Tom, Verbeke Johan, Verleye Johan (Eds.), (2001) Hogeschool voor Wetenschap en Kunst - Departement Architectuur Sint-Lucas, Campus Brussel, ISBN 80-76101-05-1
summary	"Space," which has long been an important concept in architecture (Bloomer & Moore, 1977; Mitchell, 1995, 1999), has attracted interest of researchers from various academic disciplines in recent years (Agnew, 1993; Benko & Strohmayer, 1996; Chang, 1999; Foucault, 1982; Gould, 1998). Researchers from disciplines such as anthropology, geography, sociology, philosophy, and linguistics regard it as the basis of the discussion of various theories in social sciences and humanities (Chen, 1999). On the other hand, since the invention of Internet, Internet users have been experiencing a new and magic "world." According to the definitions in traditional architecture theories, "space" is generated whenever people define a finite void by some physical elements (Zevi, 1985). However, although Internet is a virtual, immense, invisible and intangible world, navigating in it, we can still sense the very presence of ourselves and others in a wonderland. This sense could be testified by our naming of Internet as Cyberspace -- an exotic kind of space. Therefore, as people nowadays rely more and more on the Internet in their daily life, and as more and more architectural scholars and designers begin to invest their efforts in the design of virtual places online (e.g., Maher, 1999; Li & Maher, 2000), we cannot help but ask whether there are indeed sensible spaces in Internet. And if yes, these spaces exist in terms of what forms and created by what ways?To join the current interdisciplinary discussion on the issue of space, and to obtain new definition as well as insightful understanding of "space", this study explores the spatial phenomena in Internet. We hope that our findings would ultimately be also useful for contemporary architectural designers and scholars in their designs in the real world.As a preliminary exploration, the main objective of this study is to discover the elements involved in the creation/construction of Internet spaces and to examine the relationship between human participants and Internet spaces. In addition, this study also attempts to investigate whether participants from different academic disciplines define or experience Internet spaces in different ways, and to find what spatial elements of Internet they emphasize the most.In order to achieve a more comprehensive understanding of the spatial phenomena in Internet and to overcome the subjectivity of the members of the research team, the research design of this study was divided into two stages. At the first stage, we conducted literature review to study existing theories of space (which are based on observations and investigations of the physical world). At the second stage of this study, we recruited 8 Internet regular users to approach this topic from different point of views, and to see whether people with different academic training would define and experience Internet spaces differently.The results of this study reveal that the relationship between human participants and Internet spaces is different from that between human participants and physical spaces. In the physical world, physical elements of space must be established first; it then begins to be regarded as a place after interaction between/among human participants or interaction between human participants and the physical environment. In contrast, in Internet, a sense of place is first created through human interactions (or activities), Internet participants then begin to sense the existence of a space. Therefore, it seems that, among the many spatial elements of Internet we found, "interaction/reciprocity" Ñ either between/among human participants or between human participants and the computer interface Ð seems to be the most crucial element.In addition, another interesting result of this study is that verbal (linguistic) elements could provoke a sense of space in a degree higher than 2D visual representation and no less than 3D visual simulations. Nevertheless, verbal and 3D visual elements seem to work in different ways in terms of cognitive behaviors: Verbal elements provoke visual imagery and other sensory perceptions by "imagining" and then excite personal experiences of space; visual elements, on the other hand, provoke and excite visual experiences of space directly by "mapping".Finally, it was found that participants with different academic training did experience and define space differently. For example, when experiencing and analyzing Internet spaces, architecture designers, the creators of the physical world, emphasize the design of circulation and orientation, while participants with linguistics training focus more on subtle language usage. Visual designers tend to analyze the graphical elements of virtual spaces based on traditional painting theories; industrial designers, on the other hand, tend to treat these spaces as industrial products, emphasizing concept of user-center and the control of the computer interface.The findings of this study seem to add new information to our understanding of virtual space. It would be interesting for future studies to investigate how this information influences architectural designers in their real-world practices in this digital age. In addition, to obtain a fuller picture of Internet space, further research is needed to study the same issue by examining more Internet participants who have no formal linguistics and graphical training.
series	AVOCAAD
email
last changed	2005/09/09 10:48

_id	2045
authors	Balas, Egon
year	1982
title	A Class of Location, Distribution and Scheduling Problems : Modeling and Solution Methods
source	21 p., 8 + 4 p. of appendix : ill. Carnegie Mellon University, Pittsburgh, PA: Design Research Center, December, 1982. includes bibliography
summary	Discusses the potential of set covering techniques. Illustrates problem formulation techniques on several important classes of real-world problems. Also describes a class of algorithms for solving set covering problems, based on cutting planes, heuristics and subgradient optimization
keywords	problem solving, methods, algorithms, problem definition, modeling, optimization, operations research
series	CADline
last changed	1999/02/12 15:07

_id	cf2003_m_040
id	cf2003_m_040
authors	BAY, Joo-Hwa
year	2003
title	Making Rebuttals Available Digitally for Minimising Biases in Mental Judgements
source	Digital Design - Research and Practice [Proceedings of the 10th International Conference on Computer Aided Architectural Design Futures / ISBN 1-4020-1210-1] Tainan (Taiwan) 13–15 October 2003, pp. 147-156
summary	The problem of heuristic biases (illusions) discussed by Tversky and Kahneman (1982) that can lead to errors in judgement by human designers, when they use precedent knowledge presented graphically (Bay 2001). A Cognitive framework of belief, goal, and decision, and a framework of representation of architectural knowledge by Tzonis are used to map out the problem of heuristic biases in the human mind. These are used to discuss what aspects of knowledge can be presented explicitly and digitally to users to make rebuttal more available for human thinking at the cognitive level. The discussion is applicable to both inductive and analytic digital knowledge systems that use precedent knowledge. This discussion is targeted directly at means of addressing bias in the human mind using digital means. The problem of human bias in machine learning and generalisation are discussed in a different paper, and the problems of international or non-intentional machine bias are not part of discussion in this paper.
keywords	analogy, bias, design thinking, environmental design, heuristics
series	CAAD Futures
last changed	2003/11/22 07:26

_id	1b10
id	1b10
authors	Bay, Joo-Hwa
year	2001
title	Cognitive Biases - The case of tropical architecture
source	Delft University of Technology
summary	This dissertation investigates, i) How cognitive biases (or illusions) may lead to errors in design thinking, ii) Why architects use architectural precedents as heuristics despite such possible errors, and iii) Develops a design tool that can overcome this type of errors through the introduction of a rebuttal mechanism. The mechanism controls biases and improves accuracy in architectural thinking. // The research method applied is interdisciplinary. It employs knowledge from cognitive science, environmental engineering, and architectural theory. The case study approach is also used. The investigation is made in the case of tropical architecture. The investigation of architectural biases draws from work by A. Tversky and D. Kahneman in 1982 on “Heuristics and biases”. According to Tversky and Kahneman, the use of heuristics of representativeness (based on similarity) and availability (based on ease of recall and imaginability) for judgement of probability can result in cognitive biases of illusions of validity and biases due to imaginability respectively. This theory can be used analogically to understand how errors arise in the judgement of environmental behaviour anticipated from various spatial configurations, leading to designs with dysfunctional performances when built. Incomplete information, limited time, and human mental resources make design thinking in practice difficult and impossible to solve. It is not possible to analyse all possible alternative solutions, multiple contingencies, and multiple conflicting demands, as doing so will lead to combinatorial explosion. One of the ways to cope with the difficult design problem is to use precedents as heuristic devices, as shortcuts in design thinking, and at the risk of errors. This is done with analogical, pre-parametric, and qualitative means of thinking, without quantitative calculations. Heuristics can be efficient and reasonably effective, but may not always be good enough or even correct, because they can have associated cognitive biases that lead to errors. Several debiasing strategies are discussed, and one possibility is to introduce a rebuttal mechanism to refocus the designer’s thinking on the negative and opposite outcomes in his judgements, in order to debias these illusions. The research is carried out within the framework of design theory developed by the Design Knowledge System Research Centre, TUDelft. This strategy is tested with an experiment. The results show that the introduction of a rebuttal mechanism can debias and improve design judgements substantially in environmental control. The tool developed has possible applications in design practice and education, and in particular, in the designing of sustainable environments.
keywords	Design bias; Design knowledge; Design rebuttal; Design Precedent; Pre-parametric design; Tropical architecture; Sustainability
series	thesis:PhD
type	normal paper
email
last changed	2006/05/28 07:42

_id	eabb
authors	Boeykens, St. Geebelen, B. and Neuckermans, H.
year	2002
title	Design phase transitions in object-oriented modeling of architecture
doi	https://doi.org/10.52842/conf.ecaade.2002.310
source	Connecting the Real and the Virtual - design e-ducation [20th eCAADe Conference Proceedings / ISBN 0-9541183-0-8] Warsaw (Poland) 18-20 September 2002, pp. 310-313
summary	The project IDEA+ aims to develop an “Integrated Design Environment for Architecture”. Its goal is providing a tool for the designer-architect that can be of assistance in the early-design phases. It should provide the possibility to perform tests (like heat or cost calculations) and simple simulations in the different (early) design phases, without the need for a fully detailed design or remodeling in a different application. The test for daylighting is already in development (Geebelen, to be published). The conceptual foundation for this design environment has been laid out in a scheme in which different design phases and scales are defined, together with appropriate tests at the different levels (Neuckermans, 1992). It is a translation of the “designerly” way of thinking of the architect (Cross, 1982). This conceptual model has been translated into a “Core Object Model” (Hendricx, 2000), which defines a structured object model to describe the necessary building model. These developments form the theoretical basis for the implementation of IDEA+ (both the data structure & prototype software), which is currently in progress. The research project addresses some issues, which are at the forefront of the architect’s interest while designing with CAAD. These are treated from the point of view of a practicing architect.
series	eCAADe
email
last changed	2022/06/07 07:52

_id	8239
authors	Campello, Ruy Eduardo and Maculan, Nelson
year	1982
title	On Deep Disjunctive Cutting Planes for Set Partitioning : A Computationally Oriented Research.
source	Pittsburgh: Design Research Center, CMU [DRC-70-11-82], 10 p.
summary	Several mathematical programming problems can be formulated as Disjunctive Programming Problems. This approach offers a powerful procedure for the generation of new and strong cutting planes with desirable properties. For general integer programs, the traditional cutting plane methodologies proved less efficient than enumerative techniques. However, for certain classes of problems, such as set partitioning, cutting planes are known to be efficient. Since the disjunctive cuts are strong, they can be expected to perform better. This paper reports on computational results with disjunctive B(.) cuts for the set partitioning problem, evaluated in terms of computer resources and other independent measures in solving specific randomly generated test problems under controlled conditions. [includes bibliography].
keywords	Mathematics, Operations Research, Integer Programming, Optimization
series	CADline
last changed	1999/02/15 15:17

_id	89e4
authors	Cendes, Z.J., Shenton, D. and H. Shahnasser
year	1982
title	Adaptive Finite Element Mesh Generation Using the Delaunay Algorithm
source	3 p. : ill. Pittsburgh: Design Research Center, CMU, December, 1982
summary	Includes bibliography. A two-dimensional generator is described which automatically creates optimal finite element meshes using the Delaunay triangulation algorithm. The mesh generator is adaptive in the sense that elements containing the largest normalized errors are automatically refined, providing meshes with a uniform error density. The system runs on a PERQ computer made by Three Rivers Computer Company. It is menu oriented and utilizes multiple command and display windows to create and edit the object description interactively. Mesh generation from the object data base is automatic, although it may be modified interactively by the user if desired. Application of the mesh generator to electric machine design and to magnetic bubble simulation shows it to be one of the most powerful and easy to use systems yet devised
keywords	electrical engineering, triangulation, algorithms, OOPS, finite elements, analysis
series	CADline
last changed	2003/06/02 13:58

_id	e7b8
authors	Dahl, Veronica
year	1983
title	Logic Programming as a Representation of Knowledge
source	IEEE Computer. IEEE Computer Society, October, 1983. vol. 16: pp. 106-110 : ill. includes bibliography
summary	Logic has traditionally provided a firm conceptual framework for representing knowledge. As it can formally deal with the notion of logical consequence, the introduction of Prolog has made it possible to represent knowledge in terms of logic and also to expect appropriate inferences to be drawn from it automatically. This article illustrates and explores these ideas with respect to two central representational issues: problem solving knowledge and database knowledge. The technical aspects of both subjects have been covered elsewhere (Kowalski, R. Logic for problem solving, North- Holland pub. 1979 ; Dahl, V. on database system development through logic ACM Trans.vol.7/no.3/Mar.1982 pp.102). This explanation uses simple, nontechnical terms
keywords	PROLOG, knowledge, representation, logic, programming, problem solving, database
series	CADline
last changed	1999/02/12 15:08

_id	4eb7
authors	Kirsch, Uri
year	1982
title	Optimal Design of Continuous Prestressed Concrete Structures
source	25 p. : il. tables Pittsburgh, PA: Design Research Center, CMU, December, 1982. DRC-12-11-82. includes bibliography: p. 20-21
summary	Optimal design of continuous prestressed systems is stated in a nonlinear programming form. The design variables are the concrete dimensions, tendon coordinates, and prestressing force. The constraints are related to various behavior and design requirements and the objective function represents the overall cost. Some simplified models, intended to improve the solution efficiency, are presented. These include: explicit formulations of the general problem and the problem of minimizing the concrete dimensions; linear programming formulation of the tendon configuration and prestressing force optimization; and direct determination of the prestressing force for given concrete dimensions and tendon coordinates. Some examples illustrate the various problem formulations and solution methodology
keywords	engineering, structures, optimization, linear programming
series	CADline
last changed	1999/02/12 15:08

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