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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

The design and control of visual routines for the computation of simple geometric properties and relations

Romanycia, Marc Hector Joseph January 1987 (has links)
The present work is based on the Visual Routine theory of Shimon Ullman. This theory holds that efficient visual perception is managed by first applying spatially parallel methods to an initial input image in order to construct the basic representation-maps of features within the image. Then, this phase is followed by the application of serial methods - visual routines - which are applied to the most salient items in these and other subsequently created maps. Recent work in the visual routine tradition is reviewed, as well as relevant psychological work on preattentive and attentive vision. An analysis is made of the problem of devising a visual routine language for computing geometric properties and relations. The most useful basic representations to compute directly from a world of 2-D geometric shapes are determined. An argument is made for the case that an experimental program is required to establish which basic operations and which methods for controlling them will lead to the efficient computation of geometric properties and relations. A description is given of an implemented computer system which can correctly compute, in images of simple 2-D geometric shapes, the properties vertical, horizontal, closed, and convex, and the relations inside, outside, touching, centred-in, connected, parallel, and being-part-of. The visual routines which compute these, the basic operations out of which the visual routines are composed, and the important logic which controls the goal-directed application of the routines to the image are all described in detail. The entire system is embedded in a Question-and-Answer system which is capable of answering questions of an image, such as "Find all the squares inside triangles" or "Find all the vertical bars outside of closed convex shapes." By asking many such questions about various test images, the effectiveness of the visual routines and their controlling logic is demonstrated. / Science, Faculty of / Computer Science, Department of / Graduate

Geometric programming for engineering design optimization /

Brar, Guri Singh January 1981 (has links)
No description available.

Power Allocation Scheme in Multi-Hop MIMO Amplify-and-Forward Relay Networks

Chen, Jing-Yu 11 July 2011 (has links)
With perfect channel state information at all the transmission terminals, the asymptotic capacity of multi-hop multiple-input multiple-output(MIMO) amplify-andforward(AF) relay channels is derived. Although the derivation is based on the assumption of a large number of antennas, simulation results show that the derived expression is surprisingly accurate for even a small number of antennas, and may even be superior to existing results. In addition, based on the asymptotic result, we present different power allocation schemes to (i) minimization the transmit power; (ii) maximization the network throughput; (iii) minimization the transmit power over all source. Fortunately, the proposed power allocation problems can be formulated using geometric programming(GP). Therefore, the optimal power distribution among the multi-hop relay can be obtained efficiently. For multiuser scenarios, since it is possible that the QoS of each user cannot be satisfied simultaneously, we study jointly admission control and power allocation optimization problem. This joint problem is NP-hard. Therefor, we propose an iterative algorithm to reduced the complexity.


Stiglich, George Randall January 1981 (has links)
Optimal engineering design specifications are usually derived from an iterative design process. Here, different mathematical programs, each representing a particular problem assumption, are solved in order to gain insight into how and why an ideal design changes as model parameters vary. The mathematical technique used in this process is termed sensitivity analysis. The focus of this study is on techniques for performing such analysis on optimization problems which can be modeled as geometric programs. A dual based computationally attractive numerical procedure was developed to generate the locus of optimal solutions to prototype geometric programs corresponding to a large set of program parameter trajectories. Coefficient variation can include individual or simultaneous changes in any or all cost and exponent values. Sensitivity analysis is accomplished by numerically solving a specially constructed nonlinear initial value differential equation problem. Computational procedures were developed for computing an intitial value point, differential equation construction and solution, primal/dual conversion and problem reconstruction in the event of a primal constraint status change. A computer program written to carry out this scheme was described and used in the design of a batch process chemical plant. Preliminary results show the sensitivity analysis procedure developed in this study is attractive in terms of required computation time and perturbation flexibility of model coefficients.

Analysis of uncertainties and geometric tolerances in assemblies of parts

Fleming, Alan Duncan January 1988 (has links)
Computer models of the geometry of the real world have a tendency to assume that the shapes and positions of objects can be described exactly. However, real surfaces are subject to irregularities such as bumps and undulations and so do not have perfect, mathematically definable forms. Engineers recognise this fact and so assign tolerance specifications to their designs. This thesis develops a representation of geometric tolerance and uncertainty in assemblies of rigid parts. Geometric tolerances are defined by tolerance zones which are regions in which the real surface must lie. Parts in an assembly can slop about and so their positions are uncertain. Toleranced parts and assemblies of toleranced parts are represented by networks of tolerance zones and datums. Each arc in the network represents a relationship implied by the tolerance specification or by a contact between the parts. It is shown how all geometric constraints can be converted to an algebraic form. Useful results can be obtained from the network of tolerance zones and datums. For example it is possible to determine whether the parts of an assembly can be guaranteed to fit together. It is also possible to determine the maximum slop that could occur in the assembly assuming that the parts satisfy the tolerance specification. Two applications of this work are (1) tolerance checking during design and (2) analysis of uncertainty build-up in a robot assembly plan. I n the former, a designer could check a proposed tolerance specification to make sure that certain design requirements are satisfied. In the latter, knowledge of manufacturing tolerances of parts being manipulated can be used to determine the constraints on the positions of the parts when they are in contact with other parts.

A B-spline geometric modeling methodology for free surface simulation

Nandihalli, Sunil S. January 2004 (has links)
Thesis (M.S.)--Mississippi State University. Department of Computational Engineering. / Title from title screen. Includes bibliographical references.

Energy sensitive machining parameter optimization model

Gupta, Deepak Prakash. January 2005 (has links)
Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains ix, 71 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 67-71).

Otimização de um problema de arranjo físico via programação geométrica

Brito, Anna Karollyna Albino 24 February 2016 (has links)
Submitted by Maike Costa (maiksebas@gmail.com) on 2017-10-03T10:24:15Z No. of bitstreams: 1 arquivototal.pdf: 1182785 bytes, checksum: 09b090b0cefdf73a855f55479a9b17b1 (MD5) / Made available in DSpace on 2017-10-03T10:24:15Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1182785 bytes, checksum: 09b090b0cefdf73a855f55479a9b17b1 (MD5) Previous issue date: 2016-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Planning a physical arrangement (layout) of a given installation means making decisions on how to be prepared their work centers (MOREIRA, 2012). The design of this layout should identify where facilities are supposed to be, so that mitigates processes that do not provide operational value that activities should be allocated. This dissertation work forward the optimization of a physical arrangement problem by formulating it as a signomial geometric programming problem and solving it through representable functions as the difference between convex functions in its standard form. It was developed an algorithm to solve the problem and it should be implemented and tested to for the problem under study obtain an efficient global solution. / O planejamento de um arranjo físico (layout) de uma dada instalação significa tomar decisões sobre a forma de como serão dispostos os seus centros de trabalho (MOREIRA, 2012). O projeto deste layout deve identificar onde deverão ser alocadas as instalações de forma que mitigue processos que não fornecem valor as atividades operacionais. Esta dissertação trabalha frente à otimização de um problema de arranjo físico, formulando-o como um problema de programação geométrica signomial e resolvendo-o por meio de funções representáveis, como a diferença entre funções convexas na sua forma padrão. Desenvolveu-se um algoritmo para resolver o problema, e o mesmo deve ser implementado e testado para que o problema em estudo obtenha uma solução global eficiente.

A geometric programming based procedure to design bridge superstructures

Mehrotra, Anuj 01 August 2012 (has links)
The routine procedure for designing bridge superstructures relies heavily on the past experience of the designer and is extremely time consuming and costly to try out alternative designs. Typically, a designer is more concerned about satisfying the design requirements laid down by the American Association of State Highway and Transportation Officials (AASHTO) than in coming up with the best possible design from the economic point of view. Thus, application of suitable mathematical programming techniques to determine optimal designs can result in tremendous savings. In this thesis, a procedure based on Generalized Geometric Programming (GGP) is developed to optimally design and select bridge superstructures. The bridge superstructure design problems are formulated as GGP problems incorporating all the design considerations as specified by AASHTO and the Virginia Department of Transportation (VDOT). A primal based algorithm is used in which, the resulting optimization problems are transformed to the solution of a series of Linear Programming problems that are easy to solve. A computer implementation of the algorithm is also developed. The software is extremely versatile and user friendly. It provides several options to help determine the optimal solution under varying design conditions, and is implemented on several representative problems provided by VDOT. Comparison of the resulting optimal with the existing designs promises huge savings in terms of both cost and effort. The methodology that is developed can be used to solve other Engineering Designs Problems as well. / Master of Science

Geometric programming and signal flow graph assisted design of interconnect and analog circuits

張永泰, Cheung, Wing-tai. January 2007 (has links)
published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

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