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	cf2013_023
id	cf2013_023
authors	Yun, Wu and Miyamoto Funito
year	2013
title	An Analysis of Backbone of Outer Spatial Morphology of Campus
source	Global Design and Local Materialization[Proceedings of the 15th International Conference on Computer Aided Architectural Design Futures / ISBN 978-3-642-38973-3] Shanghai, China, July 3-5, 2013, pp. 23-37.
summary	The research is based on the theory of Space syntax (Hillier and Hanson, 1983). Just as the backbone is essential to compose the human body, two sorts of backbones of the outer spatial configuration of campus are proposed and defined in this thesis. The first is syntactically abstract, which is constituted with the axial lines to represent the relations between the buildings located in campus, and to characterize the essential spatial configuration of campus. The second is a road network which could be represented as a realistic backbone for human activities, and through which human get personal impression and knowledge of outer space of campus. Based on the concept of the backbone, several spatial patterns of campuses are explored and extracted, and the relationships with the spatial cognition and comprehension are quantitatively evaluated.
keywords	Backbone, Axial lines map, Road network, Space syntax, Spatial morphology, Space cognition.
series	CAAD Futures
email
last changed	2014/03/24 07:08

_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	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	1247
authors	Hasell, Mary Joyce
year	1983
title	Gaming Simulation: A Communication Tool for Architects and Designers
source	University of Michigan
summary	In today's technological society, people spend more and more time in built environments that they have little or no control in shaping. There is also a large gap in communication between designers of the built environment and non-designers. The language that non-designers use to communicate specific spatial needs, whether aesthetic or functional, is different from the formal language that designers use to communicate these issues with each other. Gaming simulation, as a communication tool, has a number Note of characteristics that make it useful for improving communication and increasing participation among designers and non-designers. In this study, a method of teaching the design of gaming simulation to designers of the built environment is developed. This method includes a Game Design Index or cataloging system of gaming tehniques, within the context of a game design process. A questionnaire was used to interview the designers of the most current physical design games about the gaming techniques in their games. Their answers were organized into the Game Design Index and set within the context of a process for designing a game. This process was tested by teaching a course to graduate students in Urban Planning and Architecture. Further testing was done by holding a game design workshop for professional architects. The findings indicate that it is possible to analyze existing games for their gaming techniques and to index them in an organized way. It is also possible to add this index to an existing game design process. By using this process, graduate students were able to design gaming simulations of high quality, although professionals who attended a day-and-a-half workshop, were not so successful. This latter problem was primarily the result of the complexity of the task and the time constraint imposed. This dissertation describes the game design process that was used to teach neophytes to design games as well as the Game Design Indexes for ten existing games. A comprehensive review of games concerned with physical design is included
series	thesis:PhD
email
last changed	2003/02/12 22:37

_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	a3b0
authors	Schubert, Lenhart K., Papalaskaris, Mary Angela and Taugher, Lay
year	1983
title	Determining Type, Part, Color, and Time Relationships
source	IEEE Computer. IEEE Computer Society, October, 1983. vol. 16: pp. 53-60 : ill. Includes bibliography
summary	Several kinds of inference problems arise constantly in question-answering processes, which without special handling can absorb large computational resources. One kind requires determining how two types of things are related, others require determining these or similar relationships among parts of objects, color or times. As people we are equippedÔ h) 000*°° ÔŒ with certain sensory organs, we have special ways of modeling our perception of color, categorizing and cross-correlating the entities whose localization in space and persistence in time renders them cognitively coherent and of analyzing spatial properties, such as parts structure. To match our cognitive skills AI system will need analogous special methods. The methods described in this paper are designed to supplement a deductive question-answering algorithm that is now operational. The algorithm draws on a base of logical propositions organized as semantic net
keywords	semantic networks, AI, inference, perception, cognition, color, patterns, algorithms
series	CADline
last changed	2003/06/02 13:58

_id	8b75
authors	Cullen, Ian
year	1983
title	Expert Systems in Architectural and Planning Education
source	Proceedings of the International Conference eCAADe [European Computer Aided Architectural Design Education] Brussels (Belgium) 1983, pp. IV.1-IV.15
doi	https://doi.org/10.52842/conf.ecaade.1983.x.a7j
summary	The paper discusses the problems and possibilities of a project initiated recently within the Bartlett in the general area of knowledge engineering. The aim is to assemble a set of knowledge bases which may be explored interactively by students. The system will differ from traditional CAL packages in that it will be both problem oriented - designed to extract from the students the information required to reach a specific decision - and capable of providing an explanation of its approach at any point.
keywords	Knowledge Engineering
series	eCAADe
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	8324
authors	Musso, Arne
year	1983
title	Justifying Designs
source	Proceedings of the International Conference eCAADe [European Computer Aided Architectural Design Education] Brussels (Belgium) 1983, pp. 0.1-0.9
doi	https://doi.org/10.52842/conf.ecaade.1983.x.k6l
summary	A distinction is made between non-justified (not 'unjustified') and justified designs. A good justification requires that a description of the solution space and a rule for selecting one solution should be given. The old but rarely used concept of the planning model is described and it is stressed that it is a useful aid when justifying design decisions. A simple example is presented to illustrate the method. It is pointed out that the use of computers can be helpful when dealing with large solution spaces, complicated evaluation rules and high demands on the quality of the justification. An increasing demand for design justification is observed, which may result in increased computer application. The hope is expressed that planning models will be used in this connection for better communication.
keywords	Planning Model, Design Decisions, Communication
series	eCAADe
more	http://www.tu-berlin.de
last changed	2022/06/07 07:50

_id	0cfd
authors	Zawack, Daniel J. and Thompson, Gerald L.
year	1983
title	A Dynamic Space-Time Network Flow Model for City Traffic Congestion
source	43 p. : ill. graphs Pittsburgh, PA: Design Research Center CMU, December, 1983. DRC-70-18-83. includes bibliography
summary	A space-time network is used to model traffic flows over time for a capacitated road transportation system having one-way and two-way streets. Also traffic signal lights, which change the network structure, are explicitly incorporated into the model. A linear (time) cost per unit flow is associated with each arc, and it is shown that under the model structure, travel time on a street is piecewise linear convex function of the number of units travelling on that street. Hence congestion effects are explicitly considered while maintaining the linear nature of the model. Two efficient solutions methods are proposed. A network flow solution for multiple source single destination network and a shortest path solution for a single source single destination network
keywords	dynamic programming, simulation, planning, graphs, networks, transportation
series	CADline
last changed	2003/06/02 10:24

_id	8beb
authors	Tomkinson, James H.
year	1983
title	UCAD : Building Design Automation with General Purpose Software Tools on UNIX
source	ACM IEEE Design Automation Conference proceedings (20th : 1983 : Miami Beach, Florida). pp. 774-787 : ill. includes bibliography: p. 778
summary	This paper describes a unique approach to a successful Design Automation System. It is an evolutionary approach, building on flexible, general purpose UNIX software tools. It is useful in such areas of design as circuit schematics, custom IC, backplanes, software code generation, building space management, music composition and many others. Examples from two year design automation effort known as UCAD are included
keywords	design, automation, software, UNIX, CAD, applications
series	CADline
last changed	2003/06/02 13:58

_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	4491
authors	Bouyat, M., H. Botta and Vignat, J. C.
year	1983
title	VERDI : A Computer Aided Design System for Development and City Planning
source	ACM IEEE Design Automation Conference Proceedings (20th : 1983 : Miami Beach, Florida). pp. 382-385 : ill. includes bibliography
summary	The system presented is a CAD system for use in planning road and other facility networks. Taking a draft master plan as its point of departure the system makes it possible: (1) To plan in a dynamic fashion since it permits the back-and-forth study of the interconnections between the design of the master plan and network design; (2) to preserve, from one work session to another, data that has already been acquired and calculated; (3) to make relevant technical evaluations in the following three fields: earthworks, roads, and sewage networks
keywords	CAD, urban planning, applications
series	CADline
last changed	2003/06/02 13:58

_id	620a
authors	Galle, Per
year	1983
title	A Theorem Relating to Exhaustive Generation of Floor Plans
source	Bulletin of Computer Aided Architectural Design. May, 1983. pp. 30-33 : ill
summary	Many problems arise in connection with automated design of architectural floor plans. If modular grids are used, one problem is to avoid repeated generation of the same plan on different modular grids. Using the concept of 'modular complexity,' the paper presents and proves a theorem which offers a solution to this problem
keywords	automation, design, planning, architecture, floor plans, grids, search, synthesis
series	CADline
last changed	1999/02/12 15:08

_id	69b3
authors	Markelin, Antero
year	1993
title	Efficiency of Model Endoscopic Simulation - An Experimental Research at the University of Stuttgart
source	Endoscopy as a Tool in Architecture [Proceedings of the 1st European Architectural Endoscopy Association Conference / ISBN 951-722-069-3] Tampere (Finland), 25-28 August 1993, pp. 31-34
summary	At the Institute of Urban Planning at the University of Stuttgart early experiments were made with the help of endoscopes in the late 1970’s. The intention was to find new instruments to visualize urban design projects. The first experiment included the use of a 16 mm film of a 1:170 scale model of the market place at Karlsruhe, including design alternatives (with trees, without trees etc). The film was shown to the Karlsruhe authorities, who had to make the decision about the alternatives. It was said, that the film gave a great help for the decision-making and a design proposition had never before been presented in such understandable way. In 1975-77, with the support of the Deutsche Forschungsgemeinschaft (German Research Foundation) an investigation was carried out into existing endoscopic simulation facilities, such as those in Wageningen, Lund and Berkeley. The resulting publication was mainly concerned with technical installations and their applications. However a key question remained: ”Can reality be simulated with endoscopy?” In 1979-82, in order to answer that question, at the Institute was carried out the most extensive research of the time, into the validity of endoscopic simulation. Of special importance was the inclusion of social scientists and psychologists from the University of Heidelberg and Mannheim. A report was produced in 1983. The research was concerned with the theory of model simulation, its ways of use and its users, and then the establishment of requirements for effective model simulation. For the main research work with models or simulation films, psychological tests were developed which enabled a tested person to give accurate responses or evidence without getting involved in alien technical terminology. It was also thought that the use of semantic differentials would make the work imprecise or arbitrary.
keywords	Architectural Endoscopy
series	EAEA
more	http://info.tuwien.ac.at/eaea/
last changed	2005/09/09 10:43

_id	ad7d
authors	Sethi, Awanti P. and Thompson, Gerald L.
year	1983
title	Solution of Constrained Generalized Transportation Problems Using the Pivot and Probe Algorithm
source	17 p. Pittsburgh PA: Design Research Center, CMU, December, 1983. DRC-70-17-83. includes bibliography
summary	In this paper the authors use a specialized version of their Pivot and Probe algorithm to solve generalized transportation problems with side constraints. The dual of an m x n generalized transportation problem with t side constraints is a linear program with m + n + t variables and up to m x n constraints. They solve the dual problem using the probe operation to select only the most important constraints to consider. Also presented is a computational experience on problems of sizes up to 180 x 180, having various degrees of density and having as many as 10 side constraints. It was found that for a given size and density, problems become harder to solve as the number of side constraints increases. Ô h)000*°° ÔŒ Also, for a fixed number of side constraints, the solution difficulty increases with size and density. The authors found that their method was able to solve problems of the quoted sizes relatively quickly, with relatively few pivots, and without using basis reinversion
keywords	linear programming, topology, planning, constraints, operations research, algorithms, methods
series	CADline
last changed	2003/06/02 10:24

_id	452c
authors	Vanier, D. J. and Worling, Jamie
year	1986
title	Three-dimensional Visualization: A Case Study
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 92-102
summary	Three-dimensional computer visualization has intrigued both building designers and computer scientists for decades. Research and conference papers present an extensive list of existing and potential uses for threedimensional geometric data for the building industry (Baer et al., 1979). Early studies on visualization include urban planning (Rogers, 1980), treeshading simulation (Schiler and Greenberg, 1980), sun studies (Anon, 1984), finite element analysis (Proulx, 1983), and facade texture rendering (Nizzolese, 1980). With the advent of better interfaces, faster computer processing speeds and better application packages, there had been interest on the part of both researchers and practitioners in three-dimensional -models for energy analysis (Pittman and Greenberg, 1980), modelling with transparencies (Hebert, 1982), super-realistic rendering (Greenberg, 1984), visual impact (Bridges, 1983), interference clash checking (Trickett, 1980), and complex object visualization (Haward, 1984). The Division of Building Research is currently investigating the application of geometric modelling in the building delivery process using sophisticated software (Evans, 1985). The first stage of the project (Vanier, 1985), a feasibility study, deals with the aesthetics of the mode. It identifies two significant requirements for geometric modelling systems: the need for a comprehensive data structure and the requirement for realistic accuracies and tolerances. This chapter presents the results of the second phase of this geometric modelling project, which is the construction of 'working' and 'presentation' models for a building.
series	CAAD Futures
email
last changed	2003/05/16 20:58

_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

_id	8c67
authors	Brachman, Ronald J., Levesque, Hector J. and Fikes, Richard E.
year	1983
title	Krypton : A Functional Approach to Knowledge Representation
source	IEEE Computer. IEEE Computer Society, October, 1983. vol. 16: pp. 67-73 : ill. includes bibliography
summary	While the basic ideas of frame systems are straight forward, complication arise in their design. A design strategy was developed and have been implemented in a representation system called Krypton. Krypton distinguishes between definitional and factual information by using both frame- based and logic-based languages. The result is a system defined in functional not structural terms
keywords	AI, frames, knowledge, representation, systems
series	CADline
last changed	2003/06/02 10:24

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