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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.

A distributed graph reducer for lazy functional languages /

Howson, Christopher January 1992 (has links)
This thesis describes a model for distributed graph reduction implemented on a network of transputers. The model allows variable size communications between processors, by exchanging subgraphs instead of single nodes. Functional languages with lazy semantics have graph nodes representing unevaluated arguments. These nodes require special treatment by the run time system because they must not be copied. By checking the structure of the transmitted subgraphs, it is possible to determine which unevaluated expressions have no external references to them and so may safely be included in the subgraph with no overhead. This allows large subgraphs to be exchanged while reducing the demands on the communications system. This technique raises the possibility of implementations on a wide variety of distributed computers such as networks of workstations, which hitherto has been considered impractical.

A partial implementation of the contour model of block structured processes

Laviana, Lyn D January 1974 (has links)
No description available.

Enhancing network communication in NPSNET-V virtual Environments using XML : Described dynamic Behavior (DBP) Protocols

Fischer, William D. 09 1900 (has links)
The existing component protocols, as well as new protocols introduced at runtime into NPSNET-V are written in their native programming language. As a result, they require authoring and compiling by a trained programmer. The long time frame required to change or introduce new protocols into NPSNET-V, a dynamically extensible virtual environment, detracts from the dynamicism of the virtual environment. Networking optimization thresholds to support NPSNET-V needed to be determined to ensure that the networking is performed efficiently, and system resources to other systems, such as graphics rendering, are maximized. This thesis implements component protocols described using Extensible Markup Language (XML) into NPSNET-V. These protocols are created with different fidelity resolutions for each protocol, which can be swapped at runtime based on the network state. Network testing was performed to find the ideal maximum packet rates based on the impact on CPU utilization and packet loss. By using XML, non-programmers can edit protocols for inclusion in a simulation at runtime. Important contributions include adding protocols to NPSNET-V with high-resolution and low-resolution versions, described by XML documents. Basic network optimization is added to NPSNET-V to take advantage of the protocolsα resolution switching ability. The network testing revealed a linear correlation between the packet sending rate and CPU utilization, and a polynomial correlation between the packet sending rate and percentage packet loss. / US Army (USA) author

Determination of reservoir daily operation policies by stochastic dynamic programming

Tsou, C. Anthony January 1970 (has links)
Reservoir operation policies are often formulated deterministically on the basis of critical flow hydrology. However, if a dynamic river daily flow forecast system is available for the whole season, the forecast information should be fully utilized in reservoir regulation. Given such a forecast system, two approaches to determining optimal daily operation policies for a single purpose flood control reservoir are suggested. Both approaches use stochastic dynamic programming: one involves the minimization of the expected value of flood damages, and the other involves minimizing the probability of occurrence of an undesirable event, which is a flood damage exceeding a certain amount. The probabilistic approach not only offers a set of alternative optimal daily operation policies, but also indicates the probabilities of being able to achieve the objectives, and thus it forms a basis for comparing and evaluating the alternative objectives. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Duality in convex programming

Muir, David Charles William January 1966 (has links)
Problems of minimizing a convex function or maximizing a concave function over a convex set are called convex programming problems. Duality principles relate two problems, one a minimization problem, the other a maximization problem, in such a way that a solution to one implies a solution to the other and that the minimum value of one is equal to the maximum value of the other. When the functions are linear and the constraint sets are polyhedral, the problems are called linear programming problems. Their duality is well-known. Certain duality results of linear programming can be extended to convex programming by means of the theory of conjugate convex functions introduced by Fenchel ([1], [2]). In this thesis the theory of conjugate functions is generalized and applied to convex programming problems. In particular a duality theorem is given for a class of convex programming problems. This theorem is compared with a duality theorem for convex programming problems given by Dorn [3]. / Science, Faculty of / Mathematics, Department of / Graduate

A convex hull algorithm optimal for point sets in even dimensions

Seidel, Raimund January 1981 (has links)
Finding the convex hull of a finite set of points is important not only for practical applications but also for theoretical reasons: a number of geometrical problems, such as constructing Voronoi diagrams or intersecting hyperspheres, can be reduced to the convex hull problem, and a fast convex hull algorithm yields fast algorithms for these other problems. This thesis deals with the problem of constructing the convex hull of a finite point set in R . Mathematical properties of convex hulls are developed, in particular, their facial structure, their representation, bounds on the number of faces, and the concept of duality. The main result of this thesis is an O(nlogn + n[(d+1)/2]) algorithm for the construction of the convex hull of n points in Rd. It is shown that this algorithm is worst case optimal for even d≥2. / Science, Faculty of / Computer Science, Department of / Graduate

Multicriteria linear fractional programming

Choo, Eng-Ung January 1981 (has links)
The object of this thesis is to study the multi-criteria linear fractional programming problems (MLFP). The characterizations of efficiency, weak efficiency and proper efficiency are derived. In the bicriteria case, the set E of all efficient solutions of (MLFP) is path-connected by a finite number of line segments and the efficient frontier F(E) can be evaluated by using the row parametric technique in linear programming. The weakly efficient (respectively, properly efficient) solutions can be generated by solving the generalized Tchebycheff norm problems (Tβ) (respectively, (βα)) with different parameters β and α. The set E[sup=W] of all weakly efficient solutions of (MLFP) is compact and path-connected by finitely many line segments. A dual problem is formulated which is a natural extension of the usual dual in linear programming, the Wolfe dual in nonlinear programming and the Isermann dual in multiple objective linear programming. Duality results are established under the assumption that the criteria are concave functions. The matrix of the dual variables of (MLFP) can be evaluated by solving L linear programs. A heuristic arrow search algorithm is developed for solving general multicriteria programming problems interactively. The decision maker merely selects his most preferred one amongst-the presented alternatives. Solutions generated are evenly distributed over the desired neighbourhood of the weakly efficient frontier. The algorithm is convergent in the bicriteria case, with appropriate convexity conditions. When applied to solve (MLFP), the arrow search algorithm uses only the linear programming techniques. / Business, Sauder School of / Graduate

Program manipulation using a grammar-based meta-programming system

Cameron, Robert Douglas January 1983 (has links)
Program manipulation is defined as the automated or semi-automated tailoring, modification or transformation of software to achieve programs with improved performance or other characteristics or to adapt programs to alternative uses. Program manipulation programs (and other sorts of software tool as well) are characterized as "programs about programs" or meta-programs. It is proposed that the implementation of these meta-programs be aided by a new type of meta-tool, the meta-programming system, which is characterized by its systematic treatment of programs as data objects. In support of the meta-programming system concept, a grammar-based scheme (called GRAMPS) for specifying meta-programming systems is put forward. This scheme is illustrated in its particular application to the programming language Pascal (yielding a specification for the meta-programming system Pascal MPS). The suitability of GRAMPS-based systems for implementing meta-programs is evaluated through theoretical consideration of the properties of GRAMPS systems in general, and an analysis of programming experiments using Pascal MPS in particular. The use of meta-programming systems for program manipulation tasks is analysed with respect to several application areas. Meta-programming systems are compared with various alternatives for the implementation of program transformations. Several types of programming utility are discussed including the use of meta-programs to develop versions of target programs specialized for program analysis. The use of meta-programming systems in the implementation of syntactic editors and integrated program manipulation systems is also considered. The results presented support both the GRAMPS scheme itself and the grammar-based treatment of programs as data objects in general. From a theoretical viewpoint, GRAMPS was found to have four important completeness properties. From an experimental perspective, Pascal MPS was found to be generally convenient and practical for large-scale applications. In each of the application areas considered, the meta-programming system approach compared favorably with available alternatives. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The role of exception mechanisms in software systems design

Atkins, Margaret Stella January 1985 (has links)
Exception handling is a crucial aspect of practical programming, particularly in systems allowing logical concurrency such as multi-process distributed systems. First, a survey of existing exception handling mechanisms in operating systems is performed, which shows a diversity of implementations, depending on the process model and the method of inter-process communication. The thesis then develops a model for designing software which exploits the different mechanisms for handling normal and exceptional events. The model is applicable in many multi-process programming environments, and not only preserves modularity, but also enhances efficiency and reliability, while often increasing concurrency. To derive such a model, exceptions in multi-process software are classified primarily according to the program level at which they are detected and handled. Server-to-client exceptions are of particular interest because of their ubiquity; these are exceptions detected by a server and handled by a client. The model treats systems programs as event driven, and proposes dividing the events into normal or exceptional, according to the cost and mechanisms for handling them. Techniques are described for designing software according to three criteria: minimising the average run-time, minimising the exception processing time, and incrementally increasing the program's functionality. Many examples are given which illustrate the use of the general model. Program paradigms in several languages and in several systems are introduced to model features which are system dependent, through illustrative examples for asynchronous i/o multiplexing, and for exception notification from a server to its client or clients. Finally, some programs which have been implemented according to the rules of the model are described and compared with their more conventional counterparts. These programs illustrate the practicality and usefulness of the model for diverse systems and concurrent environments. / Science, Faculty of / Computer Science, Department of / Graduate

Necessary conditions for a solution of a non-linear programming problem

Lee, Linda May January 1973 (has links)
The conditions required for a solution of general non-linear programming problems of the form min{f(x): x є X, g(x) ≤ 0, h(x)=0}; where f is called the objective function, g the inequality constraint and. h the equality constraint, are presented in this thesis. The following cases are studied: (1) X, a finite dimensional space; f, a real valued function; and g and h finite dimensional vector functions. (2) X, an infinite dimensional space; f, a real valued function; and g and h either finite or infinite dimensional vector functions. An application of this type of problem to optimal control will be given and the recent developments in this area will be discussed. / Science, Faculty of / Mathematics, Department of / Graduate

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