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	2e0a
authors	Besant, C.B.
year	1983
title	Computer-Aided Design and Manufacture. -- 2nd. ed
source	232 p. : ill. Chicester [West Sussex], New York: Halsted Press, 1983. includes bibliography and index -- (Ellis Horwood Series in Engineering Science)
summary	An introduction to computing as an aid to design and manufacture. Provides description of hardware and software of CAD systems, discusses their use in engineering drafting
keywords	drafting, hardware, software, CAD, CAM, practice
series	CADline
last changed	2003/06/02 13:58

_id	e10e
authors	Billon, R. and Rocca, R.
year	1983
title	Comprendre KEOPS: Logiciel de conception assistee par ordinateur en architecture
doi	https://doi.org/10.52842/conf.ecaade.1983.x.s9f
source	Proceedings of the International Conference eCAADe [European Computer Aided Architectural Design Education] Brussels (Belgium) 1983, pp. III.19-III.35
summary	En informatique graphique, la méthode la plus courante pour saisir un bâtiment consiste à dêcrire et à stocker en base de données les "pleins": les murs, planchers, composants. Cette procédure est vite fastidieuse, et ne permet pas réellement une véritable conception assistée par ordinateur. KEOPS expérimente une autre méthode qui consiste à décrire l'esquisse par ses "vides", c'est-à-dire les volumes des locaux en trois dimensions. Le logiciel opère automatiquement la transformation "filaire" en composants et ouvrages du bâtiment en exploitant un savoir technologique. Le benéfice? La réduction spectaculaire du temps de saisie et un logiciel de C.A.O. enfin opérationnel en bâtiment.
series	eCAADe
more	http://www.marseille.archi.fr
last changed	2022/06/07 07:50

_id	8e02
authors	Brown, A.G.P. and Coenen, F.P.
year	2000
title	Spatial reasoning: improving computational efficiency
source	Automation in Construction 9 (4) (2000) pp. 361-367
summary	When spatial data is analysed the result is often very computer intensive: even by the standards of contemporary technologies, the machine power needed is great and the processing times significant. This is particularly so in 3-D and 4-D scenarios. What we describe here is a technique, which tackles this and associated problems. The technique is founded in the idea of quad-tesseral addressing; a technique, which was originally applied to the analysis of atomic structures. It is based on ideas concerning Hierarchical clustering developed in the 1960s and 1970s to improve data access time [G.M. Morton, A computer oriented geodetic database and a new technique on file sequencing, IBM Canada, 1996.], and on atomic isohedral (same shape) tiling strategies developed in the 1970s and 1980s concerned with group theory [B. Grunbaum, G.C. Shephard, Tilings and Patterns, Freeman, New York, 1987.]. The technique was first suggested as a suitable representation for GIS in the early 1980s when the two strands were brought together and a tesseral arithmetic applied [F.C. Holdroyd, The Geometry of Tiling Hierarchies, Ars Combanitoria 16B (1983) 211–244.; S.B.M. Bell, B.M. Diaz, F.C. Holroyd, M.J.J. Jackson, Spatially referenced methods of processing raster and vector data, Image and Vision Computing 1 (4) (1983) 211–220.; Diaz, S.B.M. Bell, Spatial Data Processing Using Tesseral Methods, Natural Environment Research Council, Swindon, 1986.]. Here, we describe how that technique can equally be applied to the analysis of environmental interaction with built forms. The way in which the technique deals with the problems described is first to linearise the three-dimensional (3-D) space being investigated. Then, the reasoning applied to that space is applied within the same environment as the definition of the problem data. We show, with an illustrative example, how the technique can be applied. The problem then remains of how to visualise the results of the analysis so undertaken. We show how this has been accomplished so that the 3-D space and the results are represented in a way which facilitates rapid interpretation of the analysis, which has been carried out.
series	journal paper
more	http://www.elsevier.com/locate/autcon
last changed	2003/05/15 21:22

_id	2328
authors	David, B. and Décoppet, A.
year	1983
title	Architectural Programming with CAD
doi	https://doi.org/10.52842/conf.ecaade.1983.x.e3n
source	Proceedings of the International Conference eCAADe [European Computer Aided Architectural Design Education] Brussels (Belgium) 1983, pp. II.23-II.35
summary	We would like to explain to you the programme for a ten-week workshop spending ten hours per week on the architectural programming of a particular project. We have developed a special methodology which is a synthesis between Architectural Programming Methodology and Integrated CAD Methodology and have used it on two occasions. We would like to describe our experience with this workshop.
series	eCAADe
email
more	http://www.grenoble.archi.fr
last changed	2022/06/07 07:50

_id	sigradi2006_e028c
id	sigradi2006_e028c
authors	Griffith, Kenfield; Sass, Larry and Michaud, Dennis
year	2006
title	A strategy for complex-curved building design:Design structure with Bi-lateral contouring as integrally connected ribs
source	SIGraDi 2006 - [Proceedings of the 10th Iberoamerican Congress of Digital Graphics] Santiago de Chile - Chile 21-23 November 2006, pp. 465-469
summary	Shapes in designs created by architects such as Gehry Partners (Shelden, 2002), Foster and Partners, and Kohn Peterson and Fox rely on computational processes for rationalizing complex geometry for building construction. Rationalization is the reduction of a complete geometric shape into discrete components. Unfortunately, for many architects the rationalization is limited reducing solid models to surfaces or data on spread sheets for contractors to follow. Rationalized models produced by the firms listed above do not offer strategies for construction or digital fabrication. For the physical production of CAD description an alternative to the rationalized description is needed. This paper examines the coupling of digital rationalization and digital fabrication with physical mockups (Rich, 1989). Our aim is to explore complex relationships found in early and mid stage design phases when digital fabrication is used to produce design outcomes. Results of our investigation will aid architects and engineers in addressing the complications found in the translation of design models embedded with precision to constructible geometries. We present an algorithmically based approach to design rationalization that supports physical production as well as surface production of desktop models. Our approach is an alternative to conventional rapid prototyping that builds objects by assembly of laterally sliced contours from a solid model. We explored an improved product description for rapid manufacture as bilateral contouring for structure and panelling for strength (Kolarevic, 2003). Infrastructure typically found within aerospace, automotive, and shipbuilding industries, bilateral contouring is an organized matrix of horizontal and vertical interlocking ribs evenly distributed along a surface. These structures are monocoque and semi-monocoque assemblies composed of structural ribs and skinning attached by rivets and adhesives. Alternative, bi-lateral contouring discussed is an interlocking matrix of plywood strips having integral joinery for assembly. Unlike traditional methods of building representations through malleable materials for creating tangible objects (Friedman, 2002), this approach constructs with the implication for building life-size solutions. Three algorithms are presented as examples of rationalized design production with physical results. The first algorithm [Figure 1] deconstructs an initial 2D curved form into ribbed slices to be assembled through integral connections constructed as part of the rib solution. The second algorithm [Figure 2] deconstructs curved forms of greater complexity. The algorithm walks along the surface extracting surface information along horizontal and vertical axes saving surface information resulting in a ribbed structure of slight double curvature. The final algorithm [Figure 3] is expressed as plug-in software for Rhino that deconstructs a design to components for assembly as rib structures. The plug-in also translates geometries to a flatten position for 2D fabrication. The software demonstrates the full scope of the research exploration. Studies published by Dodgson argued that innovation technology (IvT) (Dodgson, Gann, Salter, 2004) helped in solving projects like the Guggenheim in Bilbao, the leaning Tower of Pisa in Italy, and the Millennium Bridge in London. Similarly, the method discussed in this paper will aid in solving physical production problems with complex building forms. References Bentley, P.J. (Ed.). Evolutionary Design by Computers. Morgan Kaufman Publishers Inc. San Francisco, CA, 1-73 Celani, G, (2004) “From simple to complex: using AutoCAD to build generative design systems” in: L. Caldas and J. Duarte (org.) Implementations issues in generative design systems. First Intl. Conference on Design Computing and Cognition, July 2004 Dodgson M, Gann D.M., Salter A, (2004), “Impact of Innovation Technology on Engineering Problem Solving: Lessons from High Profile Public Projects,” Industrial Dynamics, Innovation and Development, 2004 Dristas, (2004) “Design Operators.” Thesis. Massachusetts Institute of Technology, Cambridge, MA, 2004 Friedman, M, (2002), Gehry Talks: Architecture + Practice, Universe Publishing, New York, NY, 2002 Kolarevic, B, (2003), Architecture in the Digital Age: Design and Manufacturing, Spon Press, London, UK, 2003 Opas J, Bochnick H, Tuomi J, (1994), “Manufacturability Analysis as a Part of CAD/CAM Integration”, Intelligent Systems in Design and Manufacturing, 261-292 Rudolph S, Alber R, (2002), “An Evolutionary Approach to the Inverse Problem in Rule-Based Design Representations”, Artificial Intelligence in Design ’02, 329-350 Rich M, (1989), Digital Mockup, American Institute of Aeronautics and Astronautics, Reston, VA, 1989 Schön, D., The Reflective Practitioner: How Professional Think in Action. Basic Books. 1983 Shelden, D, (2003), “Digital Surface Representation and the Constructability of Gehry’s Architecture.” Diss. Massachusetts Institute of Technology, Cambridge, MA, 2003 Smithers T, Conkie A, Doheny J, Logan B, Millington K, (1989), “Design as Intelligent Behaviour: An AI in Design Thesis Programme”, Artificial Intelligence in Design, 293-334 Smithers T, (2002), “Synthesis in Designing”, Artificial Intelligence in Design ’02, 3-24 Stiny, G, (1977), “Ice-ray: a note on the generation of Chinese lattice designs” Environmental and Planning B, volume 4, pp. 89-98
keywords	Digital fabrication; bilateral contouring; integral connection; complex-curve
series	SIGRADI
email
last changed	2016/03/10 09:52

_id	8d5e
authors	Hayes-Roth, Frederick, Waterman, Donald A. and Lenat, Douglas B. (editors)
year	1983
title	Building Expert System
source	vii, 444 p. : ill
summary	Reading,Mass.: Addison-Wesley Pub., 1983. 1: include bibliography: p. 405-420 -- (Teknowledge Series in Knowledge Engineering. Hayes-Roth, Frederick, series editor). This book is a collaboration of 38 expert system researchers and developers. It provides a broad introduction to the concepts and methods necessary for an understanding of how these systems work
keywords	AI, expert systems
series	CADline
last changed	2003/06/02 10:24

_id	4b8e
authors	Kalay, Yehuda E. and Eastman, Charles M.
year	1983
title	Shape Operation : An Algorithm For Binary Combining Boundary Model Solids
source	November, 1983. 30 p. : ill. includes bibliography
summary	The attractiveness of shape operators to end-users of geometric modeling systems stems from their intuitive clarity. Their implementation, however, is one of the most difficult algorithms in computational geometry. This complexity is further increased by the special properties of surfaces, such as orientation, that places the algorithm in the domain of manifold theory more than of set theory. A theoretical base for applying the set-theoretic operators of union, intersection and difference to spatial domains is presented, along with an algorithm that is successful in negotiating these complexities and all their special cases (in particular the presence of coincidental surfaces). The general principles of representing solids through their bounding surfaces and topics in manifold theory and boolean algebra relevant to understanding the algorithm are also discussed. The algorithm has been successfully implemented in three different geometric modeling systems over a period of four years. Some example of its application are included
keywords	algorithms, boolean operations, solid modeling, B-rep, geometric modeling, topology
series	CADline
email
last changed	2003/05/17 10:18

_id	e26b
authors	Kalay, Yehuda E.
year	1983
title	Modeling Polyhedral Solids Bounded by Multi-Curved Parametric Surfaces
source	Computer Aided Design May, 1983. Vol. 15: pp. 141-146 : ill. includes bibliography.
summary	An integrated solids modelling system for representing and manipulating objects bounded by bicubic parametric surfaces is presented. Its basic capabilities include the representation of solids through a surface based model, such that the surface underlying any face can be replaced by another surface that has been modelled independently. Other functionalities include scaling, rotation and translation of shapes and their pairwise combination into more complex shapes by means of spatial set operators. This approach integrates within a single system the representation and manipulation of polyhedral solids bounded by multi-curved parametric surfaces, thereby combining solid modelling with surface modelling techniques
keywords	solid modeling, curves, curved surfaces, integration, systems, B-rep, intersection, boolean operations
series	CADline
email
last changed	2003/06/02 10:24

_id	a04f
authors	Smeltzer, G.T.A.
year	1983
title	Integration of Design Methods, Industrial Engineering and Informatics
doi	https://doi.org/10.52842/conf.ecaade.1983.x.q8r
source	Proceedings of the International Conference eCAADe [European Computer Aided Architectural Design Education] Brussels (Belgium) 1983, pp. I.20-I.28
summary	With the composition of a new CAD education plan the opportunity presents itself to enter into new, valuable relationships with other faculties or faculty-units, at present already working in specific fields as computing or designing. Certain aspects, which are important for CAD-Education, have already been taught for a longer period before CAD became a special, recognized part in the curriculum of the faculty. Because the university cannot afford duplication anymore, and because a unit concerned with CAD cannot have all the necessary knowhow of all specialities at its own disposal, it is an important task of that unit to integrate relevant parts or aspects of faculty or unit-curricula.
keywords	CAD Education, Curriculum
series	eCAADe
email
last changed	2022/06/07 07:50

_id	acadia03_014
id	acadia03_014
authors	Woo, J.-H., Clayton, M., Johnson, R. and Flores, B.
year	2003
title	Case Study of Tacit Knowledge Sharing in a Distributed Design Studio
doi	https://doi.org/10.52842/conf.acadia.2003.107
source	Connecting >> Crossroads of Digital Discourse [Proceedings of the 2003 Annual Conference of the Association for Computer Aided Design In Architecture / ISBN 1-880250-12-8] Indianapolis (Indiana) 24-27 October 2003, pp. 107-116
summary	This paper demonstrates the effects of experts’ tacit knowledge on improving architectural students’ design artifacts in a distributed design studio. In geographically distributed design environments, the Internet is an important medium by which architects can share tacit knowledge in the form of dialogue via online communication technologies, such as online chat and Instant Messaging (IM). In spring 2003, the National Aeronautics and Space Administration (NASA) and 8 schools conducted a collaborative design studio to develop a crew restraint system for space flights. Online chat software was used as a primary communication channel. Throughout the entire design studio, NASA professionals served as knowledge holders while undergraduate students participated as knowledge seekers. An interpretive content analysis and case study methodology were used in this study. We qualitatively observed the interactions between NASA and the students based upon two aspects: knowledge reflection and design improvement. Data were collected using document analysis of all knowledge sources and students’ design artifacts. The findings of this study indicate that the online chat system is useful in sharing tacit knowledge for the early part of design processes in a distributed design environment. Experts’ tacit knowledge appears to not only influence how students understand problems, but how they initiate conceptual design. This study provides empirical evidence regarding tacit knowledge sharing, and strengthens Schon’s (1983) claim about knowledge reflection in design studio. Furthermore, this study introduces architectural practitioners to the practical necessity of tacit knowledge sharing. This study is significant because its findings indicate the appropriate knowledge management strategy for architectural practitioners.
series	ACADIA
email
last changed	2022/06/07 07:57

_id	ecaade2012_087
id	ecaade2012_087
authors	Lorenz, Wolfgang E.
year	2012
title	Estimating the Fractal Dimension of Architecture: Using two Measurement Methods implemented in AutoCAD by VBA
doi	https://doi.org/10.52842/conf.ecaade.2012.1.505
source	Achten, Henri; Pavlicek, Jiri; Hulin, Jaroslav; Matejovska, Dana (eds.), Digital Physicality - Proceedings of the 30th eCAADe Conference - Volume 1 / ISBN 978-9-4912070-2-0, Czech Technical University in Prague, Faculty of Architecture (Czech Republic) 12-14 September 2012, pp. 505-513
summary	The concept of describing and analyzing architecture from a fractal point of view, on which this paper is based, can be traced back to Benoît Mandelbrot (1981) and Carl Bovill (1996) to a considerable extent. In particular, this includes the distinction between scalebound (offering a limited number of characteristic elements) and scaling objects (offering many characteristic elements of scale) made by B. Mandelbrot (1981). In the fi rst place such a differentiation is based upon a visual description. This paper explores the possibility of assistance by two measurement methods, fi rst time introduced to architecture by C. Bovill (1996). While the box-counting method measures or more precisely estimates the box-counting dimension D b of objects (e.g. facades), range analysis examines the rhythm of a design. As CAD programs are familiar to architects during design processes, the author implemented both methods in AutoCAD using the scripting language VBA. First measurements indicate promising results for indicating the distinction between what B. Mandelbrot called scalebound and scaling buildings.
wos	WOS:000330322400052
keywords	Box-Counting Method; Range Analysis; Hurst-Exponent; Analyzing Architecture; Scalebound and Scaling objects
series	eCAADe
email
last changed	2022/06/07 07:59

_id	caadria2010_003
id	caadria2010_003
authors	Vaughan, Josephine and Michael J. Ostwald
year	2010
title	Refining a computational fractal method of analysis: testing Bovill’s architectural data
doi	https://doi.org/10.52842/conf.caadria.2010.029
source	Proceedings of the 15th International Conference on Computer Aided Architectural Design Research in Asia / Hong Kong 7-10 April 2010, pp. 29-38
summary	In 1996 Bovill applied Mandelbrot’s fractal method for calculating the approximate visual complexity of images to architecture. This method is one of only a limited number of quantifiable approaches to provide a measure of the relative complexity of an architectural form. However, the method has rarely been tested despite many scholars uncritically repeating Bovill’s conclusions. While Bovill’s original work was calculated manually, a software program, Archimage, is presently being developed by the authors as a tool to assist architectural designers and researchers to understand the visual complexity of building designs. The present research returns to Bovill’s original architectural data (elevations of famous buildings) and re-calculates the results published therein using Archimage and the commercial software Benoit. These results are then compvared with those produced by Bovill (1996) and Lorenz (2003), to determine if any consistency can be found between the sets. The level of consistency will assist in determining the validity of Bovill’s method and provide important data in the ongoing process to refine the Archimage software and the analytical method.
keywords	Computational analysis tools; design analysis; visual complexity
series	CAADRIA
email
last changed	2022/06/07 07:58

_id	ae1b
authors	Zarnowiecka, Jadwiga C.
year	1998
title	Chaos, Databases and Fractal Dimension of Regional Architecture
doi	https://doi.org/10.52842/conf.ecaade.1998.267
source	Computerised Craftsmanship [eCAADe Conference Proceedings] Paris (France) 24-26 September 1998, pp. 267-270
summary	Modern research on chaos started in the 60's from an incredible finding that simple mathematical equations can model systems as complicated as waterfalls. In the 70's some scientists in the USA and in Europe started to find their way through the chaos. They were dealing with different spheres of science: mathematics, physics, biology, chemistry, physiology, ecology, economy. In the next 10 years? time the term 'chaos' has become generally known in science. Scientists gather in research groups according to their interests as to chaos and secondly according to their scientific specialities. (Gleick 1996) Objects that described chaos were irregular in shape, ripped. In 1975 Benoit Mandelbrot called them fractals. Fractal dimension that described fractal objects was also his invention. Fractal dimension is a way to measure quality: the degree of harshness, uneveness, irregularity of a given object. Carl Bovill (1996) showed how one can use fractal geometry in architecture and designing. This very fact made me try to use fractal geometry to deal with regional architecture. What or who is the degree of regionality of a given object to be for? A specially qualified person is able to state it nearly automatically. However, regionality is in some sense an unmeasurable feature. While dealing with data basis or checking particular projects, creation of procedures of automatic acquiring information concerning regionality is becoming a necessity.
series	eCAADe
email
more	http://www.paris-valdemarne.archi.fr/archive/ecaade98/html/20zarnowiecka/index.htm
last changed	2022/06/07 07:57

_id	bacd
authors	Abadí Abbo, Isaac
year	1999
title	APPLICATION OF SPATIAL DESIGN ABILITY IN A POSTGRADUATE COURSE
source	Full-scale Modeling and the Simulation of Light [Proceedings of the 7th European Full-scale Modeling Association Conference / ISBN 3-85437-167-5] Florence (Italy) 18-20 February 1999, pp. 75-82
summary	Spatial Design Ability (SDA) has been defined by the author (1983) as the capacity to anticipate the effects (psychological impressions) that architectural spaces or its components produce in observers or users. This concept, which requires the evaluation of spaces by the people that uses it, was proposed as a guideline to a Masters Degree Course in Architectural Design at the Universidad Autonoma de Aguascalientes in Mexico. The theory and the exercises required for the experience needed a model that could simulate spaces in terms of all the variables involved. Full-scale modeling as has been tested in previous research, offered the most effective mean to experiment with space. A simple, primitive model was designed and built: an articulated ceiling that allows variation in height and shape, and a series of wooden panels for the walls and structure. Several exercises were carried out, mainly to experience cause -effect relationships between space and the psychological impressions they produce. Students researched into spatial taxonomy, intentional sequences of space and spatial character. Results showed that students achieved the expected anticipation of space and that full-scale modeling, even with a simple model, proved to be an effective tool for this purpose. The low cost of the model and the short time it took to be built, opens an important possibility for Institutions involved in architectural studies, both as a research and as a learning tool.
keywords	Spatial Design Ability, Architectural Space, User Evaluation, Learning, Model Simulation, Real Environments
series	other
type	normal paper
email
more	http://info.tuwien.ac.at/efa
last changed	2004/05/04 11:27

_id	ecaade2009_123
id	ecaade2009_123
authors	Achten, Henri; Beetz, Jakob
year	2009
title	What Happened to Collaborative Design?
doi	https://doi.org/10.52842/conf.ecaade.2009.357
source	Computation: The New Realm of Architectural Design [27th eCAADe Conference Proceedings / ISBN 978-0-9541183-8-9] Istanbul (Turkey) 16-19 September 2009, pp. 357-366
summary	In this paper we present the results of a comprehensive literature survey on the development of collaborative design. We reviewed 324 papers on collaborative design, taken from various sources (conferences, journals, and PhD-theses). We grouped the papers based on common themes, and in that way derived a classification of themes through the last 25 years (1983-2008). Each category is described, its development, and key publications are identified.
wos	WOS:000334282200043
keywords	Collaborative design
series	eCAADe
email
last changed	2022/06/07 07:54

_id	2387
authors	Akin, Omer, Baykan, Can D. and Rao, Radha D.
year	1983
title	Searching in the UNIX Directory
source	December, 1983. 19 p. : ill., tables. includes bibliography
summary	The structure of the directory space and subjects search behaviors in the UNIX operating system environment are examined. Protocol analysis with two subjects and survey of the contents of the directory space of all users of E-VAX and X-VAX systems in the Architecture and Computer Science Systems at Carnegie Mellon University were conducted. Depth first search characterized both the organization of the directories and the behavior of the subjects. Single step as opposed to multiple step traversal of the directory tree was also prevalent in the subject`s behaviors. Recommendations for system friendliness, in term of reusability, orientation, robustness, and consistency are developed
keywords	UNIX, user interface, protocol analysis
series	CADline
email
last changed	2003/06/02 13:58

_id	8d59
authors	Andersen, J.M.
year	1983
title	CAD in Architectural Practice
source	Mechanical Engineering. July, 1983. pp. 48-54 : ill. includes a short bibliography
summary	A leading architecture/engineering firm has made use of in- house computer system since 1963. This paper discusses some special topics in using computers for the design of HVAC systems, and the process of implementing CAD in the HVAC engineering practice
keywords	computer graphics, HVAC, applications, practice, architecture
series	CADline
last changed	2003/06/02 13:58

_id	21d8
authors	Balas, Egon and Toth, Paolo
year	1983
title	Branch and Bound Methods for the Traveling Salesman Problem
source	December, 1983, 65 p. : ill., tables. Includes bibliography
summary	This paper reviews the state of the art in enumerative solution methods for the traveling salesman problem (TSP). The introduction (Section 1) discusses the main ingredients of branch and bound methods for the TSP. Sections 2,3 and 4 discuss classes of methods based on three different relaxation of the TSP: the assignment problem with the TSP cost function, the 1-tree problem with a Lagrangean objective function, and the assignment problem with a lagrangean objective function. Section 5 briefly reviews some other relaxations of the TSP, while section 6 discusses the performance of some state of the art computer codes. Besides material from the literature, the paper also includes the results and statistical analysis of some computational experiments designed for the purposes of this review
keywords	relaxation, branch-and-bound, algorithms, applications
series	CADline
last changed	2003/06/02 13:58

_id	e118
authors	Balas, Egon
year	1983
title	Disjunctive Programming and a Hierarchy of Relaxations for Discrete Optimization Problems
source	December, 1983. 38 p. : ill. includes bibliography
summary	The author discuss a new conceptual framework for the convexification of discrete optimization problems, and a general technique for obtaining approximations to the convex hull of the feasible set. The concepts come from disjunctive programming and the key tool is a description of the convex hull of a union of polyhedra in terms of a higher dimensional polyhedron. Although this description was known for several years, only recently was it shown by Jeroslow and Lowe to yield improved representations of discrete optimization problems. The author expresses the feasible set of a discrete optimization problem as the intersection (conjunction) of unions of polyhedra, and define an operation that takes one such expression into another, equivalent one, with fewer conjuncts. He then introduces a class of relaxations based on replacing each conjunct (union of polyhedra) by its convex hull. The strength of the relaxations increases as the number of conjuncts decreases, and the class of relaxations forms a hierarchy that spans the spectrum between the common linear programming relaxation, and the convex hull of the feasible set itself. Instances where this approach presents advantages include critical path problems in disjunctive graphs, network synthesis problems, certain fixed charge network flow problems, etc. The approach on the first of these problems is illustrated, which is a model for machine sequencing
keywords	polyhedra, computational geometry, optimization, programming, convex hull, graphs
series	CADline
last changed	1999/02/12 15:07

_id	41af
authors	Barnhill, Robert E.
year	1983
title	A Survey of the Representation and Design of Surfaces
source	IEEE Computer Graphics and Applications. October, 1983. vol. 3: pp. 9-16 : ill. includes bibliography
summary	The approach of devising robust surface methods applicable to arbitrarily located data was taken by the CAGD Group at the University of Utah. Adopting two broad classes of methods suitable for solving the problems (i.e., problems for which simplifying geometric assumptions cannot be made): (1) surface interpolants defined over triangles or tetrahedra and (2) distance-weighted interpolants. Interactive computer graphics was used to display surfaces for adequate visualization. Although some figures were given, it must be kept in mind that some 3-D medium, or at least motion, is necessary to understand surfaces
keywords	computational geometry, computer graphics, representation, curved surfaces, mathematics
series	CADline
last changed	2003/06/02 10:24

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