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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.
41

Global rigidity and symmetry of direction-length frameworks

Clinch, Katharine January 2018 (has links)
A two-dimensional direction-length framework (G; p) consists of a multigraph G = (V ;D;L) whose edge set is formed of "direction" edges D and "length" edges L, and a realisation p of this graph in the plane. The edges of the framework represent geometric constraints: length edges x the distance between their endvertices, whereas direction edges specify the gradient of the line through both endvertices. In this thesis, we consider two problems for direction-length frameworks. Firstly, given a framework (G; p), is it possible to nd a di erent realisation of G which satis es the same direction and length constraints but cannot be obtained by translating (G; p) in the plane, and/or rotating (G; p) by 180 ? If no other such realisation exists, we say (G; p) is globally rigid. Our main result on this topic is a characterisation of the direction-length graphs G which are globally rigid for all "generic" realisations p (where p is generic if it is algebraically independent over Q). Secondly, we consider direction-length frameworks (G; p) which are symmetric in the plane, and ask whether we can move the framework whilst preserving both the edge constraints and the symmetry of the framework. If the only possible motions of the framework are translations, we say the framework is symmetry-forced rigid. Our main result here is for frameworks with single mirror symmetry: we characterise symmetry-forced in nitesimal rigidity for such frameworks which are as generic as possible. We also obtain partial results for frameworks with rotational or dihedral symmetry.
42

Simulation of the synthesis of metal-organic framework materials

Cessford, Naomi Faye January 2014 (has links)
The objective of this work was to develop a molecular simulation method with the capacity to represent the synthesis of metal-organic framework (MOF) structures to the extent of being able to accurately predict the MOF structures that form under specified reaction conditions. MOFs are a class of porous, crystalline solids composed of metal-ion vertices coordinated by organic linker molecules. MOFs are created in a self-assembly process in which the building blocks (reactants) retain their integrity. Under different experimental synthesis conditions, a particular combination of building blocks can react to form differing MOF structures. The structure of MOFs confers a large degree of tunability, allowing almost limitless potential for the materials to be designed with the capacity to fulfil the requirements of a specific application. Consequently, MOFs have shown promise for a variety of applications including gas storage, separation and catalysis. Thus, the ability to accurately predict the MOF formed by specifying reaction parameters such as temperature, pH and the concentrations of reactants has great potential because, upon identification of a promising hypothetical structure for a particular application, the synthesis conditions ascertained via the simulation method could be used as the basis for the determination of an experimental synthesis procedure. In addition, a simulation method with the capacity to predict MOF structures affords the opportunity to gain a fundamental understanding of the influence of the experimental synthesis conditions on the structures formed, so as to enable progress towards the rational design of MOFs. In this work, the experimental synthesis of MOFs via self-assembly is modelled using a kinetic Monte Carlo approach. Ideally, simulation of the self-assembly of the building blocks would be modelled atomistically with all atoms in the reactant and solvent molecules represented explicitly. However, due to the prohibitive computational requirements of such a simulation, in this work a “potential-of-mean-force” (PMF) approach was used to represent the solvent implicitly by encompassing the solvent-mediated behaviour in the interactions between building blocks, thereby reducing the computational cost. The PMF approach to the implicit representation of the solvent involved the utilisation of effective pairwise interactions between the constituents of the reactant species. Following extensive testing to ensure that the explicit-solvent behaviour of the reactants could be replicated using the PMF method, this approach allowed computationally efficient implicit-solvent simulations of the synthesis of MOF materials to be performed. Thorough assessment of a method developed to simulate the synthesis of MOFs required investigation of a system which, under different reaction conditions, forms differing structures. In this respect, the cobalt succinates represent an unparalleled test because under different reaction temperatures, reactant concentrations, pH and reaction time, seven different phases have been identified. Furthermore, the parameters within which the different phases form have been clearly delineated experimentally. The method developed has been employed, under the appropriate reaction conditions, to simulate the synthesis of two of the seven identified phases of the cobalt succinates. Whilst still subject to computational limitations, the MOF-synthesis simulation method yields structures characteristic of those expected experimentally under corresponding reaction conditions.
43

Uma abordagem orientada por objectos para meta-heurísticas multiobjectivo

Claro, João Alberto Vieira de Campos Pereira January 2002 (has links)
Nesta dissertação convergem algumas linhas de investigação na área das meta-heurísticas que, recentemente, têm vindo a ser objecto de particular atenção: a flexibilização, ou seja, a introdução de mecanismos de modificação de componentes e estratégias elementares, o desenvolvimento de abordagens orientadas por objectos, e a adaptação a contextos multiobjectivo. Esta convergência justifica-se pelo facto de as abordagens orientadas por objectos promoverem naturalmente a flexibilização, e pela constatação da inexistência, até ao momento, de abordagens orientadas por objectos para a área das metaheurísticas multiobjectivo. Foi feita uma análise e sistematização do domínio e, em particular, das metaheurísticas multiobjectivo, com ênfase na perspectiva da flexibilização. Esta sistematização fundamenta a proposta de um template para pesquisa local multiobjectivo, e de um conjunto de estratégias genéricas de flexibilização.
44

FV-RAD : a practical framework for rapid application development

Ferreira, Luís Filipe Rocha Maia January 2009 (has links)
Estágio realizado na OPT-Optimização e Planeamento de Transportes, S.A / Tese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 2009
45

Relationships Between Psychogenic Needs and Theoretical Frameworks of Psychotherapists

Ahern, Dennis E. 01 May 1983 (has links)
Each psychotherapist has a personal theoretical framework, that is, a set of assumptions on which his or her psychotherapy is based. It appears from the published writings and opinions of therapists that therapists generally concur that a major factor in the formation of an individual therapist's theoretical framework is the therapist's personality. This study was designed to address this issue by examining the relationship between the psychogenic needs and theoretical framework of the therapist. From an accessible population of 178, responses were obtained from 153 therapist participants (108 males and 45 females) from five Utah training programs and three experience levels. Each of the participants completed a measure of theoretical framework (developed by the author) which assessed general adherence to the principles and techniques of person-centered, behavioral, and rational-emotive therapy. Based on scales from Jackson's Personality Research Form the following psychogenic need variables were also derived: Need for Achievement, Need for Affiliation, Need for Dominance, Need for Exhibition, Need to Give Nurturance, and Need for Order. Other independent variables were based on the experience levels and training programs of the therapists. Multiple regression analyses yielded uniformly small (less than 13.5% variance accounted for), generally non-significant relationships. The only clear relationship between a psychogenic need and the theoretical framework variables was between Need for Affiliation and the person-centered therapy variables. The experience level of the therapist accounted for the greatest portion of variance in the behavior therapy variables. There was no clear relationship between the rational-emotive therapy variables and any of the independent variables. The low magnitude of these results may be partially explained by the relatively low reliability of the research variables. Further, if a relationship does exist between psychogenic needs and theoretical framework, it may not be a linear relationship which was the assumptive basis of the analyses used in the research. An interesting finding was that scores of concurrence with the three theoretical schools had positive intercorrelations of between .14 and .54. An implication of this finding is that theoretical framework may be multidimensional versus unidimensional as it has previously been conceptualized. In summary, this research does not support the relationship between the psychogenic needs and theoretical framework of the therapist. However, given the theoretical emphasis placed on the topic, and the difficulties with this research, further research in the area appears warranted before the issues can be more definitely resolved.
46

A Study on Legal System of Pawnbroking Industry Management

Ko, Chiao-yi 20 August 2009 (has links)
¡§Pawnbroking Industry¡¨ is an ancient industry in our country, its history has existed over one thousand year at least. Initially, pawnbroking industry began to develop from the temple. With the religious spirit of expressing humanitarianism, the temple used its principal to provide the poor with a method of loaning money. Nevertheless, as times goes by and a business characteristic of earning profits easily, the industry has gradually combined with usury behavior and transformed into another diverse sort of complex industry and fairly differ from the original concept of charity as well. As it¡¦s proclaimed in Article 8 of Constitution of the Republic of China that ¡§Financial institutions shall, in accordance with law, be subject to State control.¡¨ Even though, pawnbroking industry isn¡¦t a portion of financial institutions, it¡¦s still necessary to legally manage because the characteristic of making profit and the business model. Consequently, for the sake of achieving the above goal, our government established ¡§Pawnbroking Industry Management Directions¡¨ in 1940 to be in accordance with, and the directions have lasted for sixty years. Afterwards, to strengthen the lawful position and suit the demand of times change, ¡§Pawnbroking Industry Act¡¨ was legislated and declared officially in 2001, and the act became the significant legislation of pawnbroking industry management in our country. From then on, the official authority of pawnbroking industry management has been definitely empowered by the law, and been epochal significance in the history of pawnbroking industry management. The legal system of management is examined herein by the basic methods of administrative law, namely, the five major frameworks, including administrative principles, administrative organization, limitation of administrative power, administrative relief, and administrative supervision from every respect and viewpoint. Meanwhile, bibliography exploration, historical narration, comparative analysis, and practice observation are adopted as the principal research approaches to explore whether there¡¦s any improvement required regarding the legal system of pawnbroking industry management on the basis of five major frameworks of administrative law. Additionally, practical implementation and suggestions for regulations and actions concerning future pawnbroking industry management are hereby provided, which can be a reference for the police authorities in exercising their powers, establish the administrative standards of Taiwan according to law, and improving the legal appearance of our country under the rule of law.
47

PHP karkasų architektūrinis tyrimas / PHP frameworks architectural research

Vaitkūnas, Mantas 26 August 2013 (has links)
Šiuo metu yra sukurta daugybė PHP karkasų, tačiau yra mažas informacijos kiekis subjektyviai nusakančios privalumus ir trūkumus. Pagrindinis darbo tikslas yra ištirti Yii, Zend 2 ir Symfony2 karkasus, bei juos palyginti. Šiame dokumente aprašytas darbas susideda iš trijų pagrindinių dalių. Pirmoji dokumento dalis – karkasų apžvalga. Šioje dalyje apžvelgiami Yii, Zend 2 ir Symfony2 karkasai. Antrojoje (projektinėje) dokumento dalyje aprašoma sistema, kuri yra kuriama atskirai su kiekvienu iš karkasų. Šiame skyriuje pateikiama visa sistemos architektūra, reikalavimai sistemai, bendri apribojimai, statinis vaizdas. Trečioje (tyrimo ir eksperimentinėje) dokumento dalyje, detalizuojami atlikti tyrimai ir eksperimentai. Tyrimai vykdomi kuriant QR kodų generavimo ir vartotojų lankomumo statistikų sekimo sistemą. Šių tyrimų metu tiriamas darbo imlumas, našumas, funkcionalumas ir atlikta pasirinktų karkasų kodo analizė. / Currently there are created plenty of different PHP frameworks, but the amount of information subjectively outlining the pros and cons is low. Main purpose of this research is to investigate and compare three main frameworks: Yii, Zend 2 and Symfony. This document describes work consisting of three main parts. The first part of the document is a framework review. This section provides and overview of Yii, Zend 2 and Symfony2 frameworks. Second (design) part is a description of the system which was developed using each of the frameworks. This section contains the entire system architecture, system requirements, general restrictions and static image. The third (research and experimental) part of the document, consists of detailed studies and experiments. Studies were carried out in developing QR code generation and visitor monitoring system. During these studies the capacity, performance, functionality and code of three main frameworks were analyzed.
48

Design and implementation of a framework for semi-autonomous mobile robots

Sanders, David Marc 21 January 2011 (has links)
The design of a framework to control multiple semi-autonomous mobile robots is presented. The goals are to create a flexible framework that allows easy task reconfiguration for a fleet of mobile robots, and to provide a means of off-loading computationally intensive tasks to a central server. Four major components are specified: controllable devices, application servers, an application directory, and a mobile management system. Remote firmware upgrades via the mobile management system are achieved with the remotely managed operating system framework or RMOS. A prototype was created using field programmable gate arrays and system on a programmable chip technology from Altera. It was built with the application of selective herbicide spraying in mind. Although the prototype was a successful implementation of the designed framework, selective herbicide application was not implemented. A broad-leaf weed detection algorithm using Boltzmann machines was investigated. Its performance was good, but similar to that obtained by a statistical analysis of the input images of a lawn.
49

Design and implementation of a framework for semi-autonomous mobile robots

Sanders, David Marc 21 January 2011 (has links)
The design of a framework to control multiple semi-autonomous mobile robots is presented. The goals are to create a flexible framework that allows easy task reconfiguration for a fleet of mobile robots, and to provide a means of off-loading computationally intensive tasks to a central server. Four major components are specified: controllable devices, application servers, an application directory, and a mobile management system. Remote firmware upgrades via the mobile management system are achieved with the remotely managed operating system framework or RMOS. A prototype was created using field programmable gate arrays and system on a programmable chip technology from Altera. It was built with the application of selective herbicide spraying in mind. Although the prototype was a successful implementation of the designed framework, selective herbicide application was not implemented. A broad-leaf weed detection algorithm using Boltzmann machines was investigated. Its performance was good, but similar to that obtained by a statistical analysis of the input images of a lawn.
50

Design, Synthesis, and Characterization of Porous Metal-Organic Materials

Park, Jinhee 03 October 2013 (has links)
Porous metal-organic materials (MOMs) are assembled through coordination between two types of building units, metal or metal-containing nodes and organic linkers. Metal-organic frameworks (MOFs) have 3-D infinite structures and are especially known for high porosity and enormous surface area, leading to diverse applications such as selective gas separation, gas storage and catalysis. In contrast, metal-organic polygons/polyhedra (MOPs) as discrete molecular coordination assemblies are soluble in certain solvents, allowing us to study their solution-chemistry. In the first project, a microporous MOF with 1-dimensional (1D) bridging helical chain secondary building units (SBUs) shows facile transition from micro- to mesoporosity upon activation conditions. The quickly activated MOF shows permanent microporosity while the slow removal of coordinated aqua ligand results in formation of the mesopores in the microporous MOF. Second, a strategy to introduce not only the functional groups but also functionalized meso-cavities into microporous MOFs through metal-ligand-fragment coassembly has been studied. With this functionalization, the interior of the MOFs can be tuned by a wide range of functional groups on the ligand fragments, including polar and ionic ones. Depending on the functional groups on the ligand fragments, the introduced cavities can be extended to mesopores in a controllable manner. Third, a MOF constructed from dicopper paddlewheels and a predesigned ligand bearing carboxylate, pyridine, and amide groups enables selective adsorption of CO2 over CH4 and high H2 adsorption. The cooperative catalytic activity in a tandem one-pot deacetalization-Knoevenagel condensation was demonstrated. In the fourth and fifth section, an optically and thermally switchable azobenzene was introduced into a MOF and MOPs, respectively. The freshly synthesized MOF adsorbed a significant amount of CO2. Upon light irradiation, the adsorbed gas molecules were squeezed out of the MOF due to the change of conformation of the azobenzene groups inside the pores. The adsorbent returned to its original state when allowed to stay with gentle heating. In addition, solubility of srMOPs was optically controlled by trans-cis isomerization of the azobenzene moieties. Interestingly, guest molecules were trapped during cis to trans isomerization and released in the trans to cis conversion. This srMOP can be applied to uses requiring stimuli responsive capture and release of guest molecules, such as in controlled drug delivery systems. Finally, an organic linker with multiple conformations was used to synthesize both single and core-shell molecular squares, whose formations were controlled by reaction temperatures. Intriguingly the core-shell structure assembly was successfully employed as a template to prepare a heterobimetallic assembly, in which the metal substitution occurred exclusively in the core. This work might pave the way for the exploration of enzyme-mimicking molecular catalysts.

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