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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.
201

LIEF: An Algorithm for Learning Information Extraction Rules from Unstructured Documents

Pen, Chih-Jen 02 August 2001 (has links)
In the past, information was stored more or less well-structured in database. Nowadays, a lot of information is presented in unstructured format. The management of and retrieval from such large vast of textual information has been a challenging issue for organizations or individuals. Information extraction is the process of extracting relevant data from semi-structured or unstructured documents and transforming them into structured representations. Many information extraction learning techniques have been proposed. However, they are ineffectiveness on unstructured documents. Thus, in the research, we proposed a new information extraction learning algorithm, called LIEF, that enhancing existing information extraction learning techniques. According to the empirical evaluations on news documents that are unstructured format, the LIEF algorithm proposed showed its capabilities in accuracy rate.
202

Ariadne’s Thread: A Letter to Descartes

Christou, Geoffrey 06 September 2013 (has links)
As Galileo peered through a lens to see the twinkle of the Jovian moons, and Antonie Van Leeuwenhoek did the same to study the tremulous basis of all life, so the fabric of threads we weave across time and space – the vast net of relations that bind and separate us – is visible only through a lens. Footprints in the snow and the weathered stone steps of buildings hint at the shape of these threads, but the coming of spring and the hardness of stone limit our observations. The Global Positioning System (GPS) now provides us a lens to see the path that individuals, families, and communities take in space-time -- their worldlines. When millions of GPS signatures are collected from hundreds of individuals, heritable patterns emerge that embody particular individual’s ideas and practices, as well as those of the society and the environment in which they operate. Besides providing a tool to test assumptions about how space is used, I argue in this thesis that by allowing us to glimpse a terra incognita, mapping worldlines also provides a unique perspective on our spatial relationship to one another.
203

Path Building in Emerging Entrepreneurial Firms: An Investigation of Networks in the Making

Iarossi, Juliana 24 July 2012 (has links)
Underpinning economic growth is the emergence of entrepreneurial ventures with the potential to grow that boost job creation and provide new sources of products for mature companies. The critical role associated with new firms, underscores the importance of understanding how entrepreneurship unfolds. Network-based research, while leading the way to rich empirical studies provides a limited understanding of how entrepreneurial networks are built and their impact on the emergence of a new venture. Employing a multiple case study design and a perspective based on organizational path building, three young technology ventures were investigated in terms of the formation of networks around five key entrepreneurial activities defined by entrepreneurs. Rich insight into new venture emergence is presented in terms of the reciprocal relationship between specific activities enacted by entrepreneurs and the networks that form to execute those activities revealing the path building mechanisms that evolve to drive network development. The findings of this research not only contribute to theories of new venture emergence, but also offer an interesting opportunity for future research into factors that may influence the outcome of entrepreneurial ventures and provide practical insight for organizations seeking to sustain or develop an entrepreneurial path.
204

K Shortest Path Implementation

Nagubadi, RadhaKrishna January 2013 (has links)
The problem of computing K shortest loopless paths, or ranking of the K shortest loopless paths between a pair of given vertices in a network is a well-studied generalization of shortest path problem. The K shortest paths problem determines not only one shortest path but the K best shortest paths from s to t in an increasing order of weight of the paths. Yen’s algorithm is known to be the efficient and widely used algorithm for determining K shortest loopless paths. Here, we introduce a new algorithm by modifying the Yen’s algorithm in the following way: instead of removing the vertices and the edges from the graph, we store them in two different sets. Then we modified the Dijkstra’s algorithm by taking these two sets into consideration. Thus the algorithm applies glass box methodology by using the modified Dijkstra’s algorithm for our dedicated purpose. Thus the efficiency is improved. The computational results conducted over different datasets, shows the proposed algorithm has better performance results.
205

Path integral Langevin dynamics of complex molecular systems: from low-temperature quantum clusters to biomolecules

Ing, Christopher 22 October 2011 (has links)
This thesis presents an implementation of path integral molecular dynamics (PIMD) for sampling equilibrium and dynamical properties within the molecular modelling toolkit (MMTK) [J. Comp. Chem. 21, 79 (2000)], an open source Python package. Rigorous simulation using this code serves to benchmark this implementation as well as the robust- ness of the path integral Langevin equation as a thermostat [J. Chem. Phys. 133, 124104 (2010)]. PIMD is used to calculate equilibrium properties for clusters of HeN-CO2 at low- temperatures, with comparison to experimental and exact results. We characterize the convergence of structural and energetic properties as a function of path-integral discretiza- tion error. The radial and angular distribution of these clusters is studied as a function of size in the absence of rotation and bosonic exchange. These distributions are subsequently used to calculate vibrational shifts of CO2. This result is compared to high-accuracy path integral Monte Carlo simulations which include rotational and exchange effects. These sim- ulations indicate that the neglect of rotational degrees of freedom leads to an unphysical localization of helium atoms and incorrect vibrational shifts when compared to experiment. Approximate real-time quantum dynamics is presented for doped helium clusters using the ring-polymer molecular dynamics (RPMD) method. The accuracy of RPMD is tested iii for low-temperature simulations and compared to exact results. Preliminary calculation of the dynamics of the helium solvated CO2 dopant with respect to the center of mass of the cluster is presented. The effect of a cartesian integrator versus a normal-mode integrator for quantum dynamics is addressed. The path integral ground-state method is applied in order to calculate T = 0 properties. A convergence study of the ground-state energy of the quantum harmonic oscillator with respect to sampling time and path discretization is shown. As a final application of this implementation, a sugar in a periodic water box is simulated at T = 300K. The calculation of rotamer populations and a dipole autocorrelation indicate negligible change with the inclusion of quantum effects. This work offers a comprehensive foundation from which to base future PIMD centered research.
206

Análise da eficácia do instrumento RECIPROC #25 em atingir o forame apical sem glide path / Analysis of the effectiveness of the instrument RECIPROC #25 to achieve the foramen without glide path

Thiane Elys Prado Arruda Cavalcante 10 February 2012 (has links)
O presente estudo avaliou a eficáciado instrumento Reciproc#25 em atingir o forame de canais de molares inferiores sem um glide path manual prévio. Para isso, uma amostra geral de 300 molares inferiores foi radiografada e previamente selecionada quanto ao grau de curvatura segundo critério de Schneider sendo divididos em classes I e II. Após a aplicação dos critérios de inclusão e exclusão, uma amostragem total de 502 canais radiculares foi incluída para formar os grupos experimentais: 253 canais no grupo de molares inferiores classe I e 249 no grupo de molares classe II. Todos os canais foram instrumentados diretamente com a lima 25, sem nenhum glide path prévio, seguindo criteriosamente as diretrizes do fabricante. Os dados foram descritos como a frequência da distribuição do número de canais (%) nos quais foi possível chegar ao forame apical sem a necessidade de glide path, assim como o número de fraturas em cada grupo. Os resultados compilados dos 2 grupos experimentais mostraram que em 93,4% do total dos canais instrumentados, o instrumento R25 foi capaz de ir até o forame apical sem a necessidade de glide path. Em 6,4% do total dos canais, o instrumento R25 não chegou até o forame apical e em somente 0,2% dos casos ocorreu fratura da lima (um caso no grupo classe I, enquanto no grupo classe II não houve nenhuma ocorrência de fratura). O teste Qui-quadrado foi realizado para verificar se uma determinada classe de canais encontra-se mais associada ou não a necessidade de glide path quando o sistema Reciproc é usado. No grupo de molares classe II houve maior número de canais (23) que o instrumento R25 não foi capaz de ir até o forame apical do que no grupo de molares classe I (9), sendo essa diferença estatisticamente significante (Qui-quadrado, p=0,020, X2=5,452). Dentro das condições experimentais do presente estudo, pode-se concluir então quea lima R25 mostrou uma alta eficácia em instrumentar toda a extensão dos canais de molares inferiores classe I e II sem a necessidade de glide path prévio. Além disso, o sistema de instrumentação proposto mostrou-se altamente seguro quanto ao índice de fratura. / The aim of the present studywas to evaluate the effectiveness of the Reciproc #25 instrument in reaching the apical foramen of mandibular molars root canals without any manual glide path. For this, a general sample of 300 mandibular molars was radiographed and graded accordantly the degree of curvature (Schneiders criteria) classes I and II. After applying the inclusion and exclusion criteria, a total of 502 root canals were included to form the two experimental groups: 253 canals in the class Igroupand 249 in the class II group. All canals were instrumented directly with R25 file, without any manual glide path, carefully following the manufactures guidelines. The pooled results of two experimental groups showed that the R25 instrument was able to reach the apical foramen without glide path in 93.4% of the cases. In 6.4%, the instrument R25 was unable to reach the apical foramen and in only 0.2% of the cases occurredinstrument fracture (one fracture in the class I group andnone in the class II group). The chi-square test was accomplished to verify that a certain class of channels is more associated with or without the need for glide path when the Reciproc system is used. . In the group of class II molar higher number of channels (23) that the instrument was not able to go to the apical foramen than in the molar class I (9), and this difference was statistically significant (Chi-square test, p = 0.020, X2 = 5.452) Within the experimental conditions of this study, it can be concluded that the file R 25 showed to be a highly effective instrument in the instrumentation of the entire length of the canals of mandibular molars class I and II without prior glide path. In addition, the instrumentation system was shown to be highly safe in the rate of fracture.
207

Statistical Critical Path Identification and Classification

Panagiotakopoulos, Georgios 01 May 2011 (has links)
This thesis targets the problem of critical path identification in sub-micron devices. Delays are described using Probability density functions (Pdfs) in order to model the probabilistic nature of the problem. Thus, a deterministic critical path response is not possible. The probability that each path is critical is reported instead. Extensive literature review has being done and presented in detail. Heuristics for accurate critical path calculations are described and results are compared to those from Monte Carlo simulations.
208

Análise da eficácia do instrumento RECIPROC #25 em atingir o forame apical sem glide path / Analysis of the effectiveness of the instrument RECIPROC #25 to achieve the foramen without glide path

Thiane Elys Prado Arruda Cavalcante 10 February 2012 (has links)
O presente estudo avaliou a eficáciado instrumento Reciproc#25 em atingir o forame de canais de molares inferiores sem um glide path manual prévio. Para isso, uma amostra geral de 300 molares inferiores foi radiografada e previamente selecionada quanto ao grau de curvatura segundo critério de Schneider sendo divididos em classes I e II. Após a aplicação dos critérios de inclusão e exclusão, uma amostragem total de 502 canais radiculares foi incluída para formar os grupos experimentais: 253 canais no grupo de molares inferiores classe I e 249 no grupo de molares classe II. Todos os canais foram instrumentados diretamente com a lima 25, sem nenhum glide path prévio, seguindo criteriosamente as diretrizes do fabricante. Os dados foram descritos como a frequência da distribuição do número de canais (%) nos quais foi possível chegar ao forame apical sem a necessidade de glide path, assim como o número de fraturas em cada grupo. Os resultados compilados dos 2 grupos experimentais mostraram que em 93,4% do total dos canais instrumentados, o instrumento R25 foi capaz de ir até o forame apical sem a necessidade de glide path. Em 6,4% do total dos canais, o instrumento R25 não chegou até o forame apical e em somente 0,2% dos casos ocorreu fratura da lima (um caso no grupo classe I, enquanto no grupo classe II não houve nenhuma ocorrência de fratura). O teste Qui-quadrado foi realizado para verificar se uma determinada classe de canais encontra-se mais associada ou não a necessidade de glide path quando o sistema Reciproc é usado. No grupo de molares classe II houve maior número de canais (23) que o instrumento R25 não foi capaz de ir até o forame apical do que no grupo de molares classe I (9), sendo essa diferença estatisticamente significante (Qui-quadrado, p=0,020, X2=5,452). Dentro das condições experimentais do presente estudo, pode-se concluir então quea lima R25 mostrou uma alta eficácia em instrumentar toda a extensão dos canais de molares inferiores classe I e II sem a necessidade de glide path prévio. Além disso, o sistema de instrumentação proposto mostrou-se altamente seguro quanto ao índice de fratura. / The aim of the present studywas to evaluate the effectiveness of the Reciproc #25 instrument in reaching the apical foramen of mandibular molars root canals without any manual glide path. For this, a general sample of 300 mandibular molars was radiographed and graded accordantly the degree of curvature (Schneiders criteria) classes I and II. After applying the inclusion and exclusion criteria, a total of 502 root canals were included to form the two experimental groups: 253 canals in the class Igroupand 249 in the class II group. All canals were instrumented directly with R25 file, without any manual glide path, carefully following the manufactures guidelines. The pooled results of two experimental groups showed that the R25 instrument was able to reach the apical foramen without glide path in 93.4% of the cases. In 6.4%, the instrument R25 was unable to reach the apical foramen and in only 0.2% of the cases occurredinstrument fracture (one fracture in the class I group andnone in the class II group). The chi-square test was accomplished to verify that a certain class of channels is more associated with or without the need for glide path when the Reciproc system is used. . In the group of class II molar higher number of channels (23) that the instrument was not able to go to the apical foramen than in the molar class I (9), and this difference was statistically significant (Chi-square test, p = 0.020, X2 = 5.452) Within the experimental conditions of this study, it can be concluded that the file R 25 showed to be a highly effective instrument in the instrumentation of the entire length of the canals of mandibular molars class I and II without prior glide path. In addition, the instrumentation system was shown to be highly safe in the rate of fracture.
209

Uma fórmula de Itô-Ventzell para caminhos Hölder / An Itô-Ventzell type formula for Hölder paths

Castrequini, Rafael Andretto, 1984- 26 August 2018 (has links)
Orientador: Pedro José Catuogno / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-26T02:18:47Z (GMT). No. of bitstreams: 1 Castrequini_RafaelAndretto_D.pdf: 917541 bytes, checksum: c03f74c254be62fceaa032d8a3fd40ec (MD5) Previous issue date: 2014 / Resumo: Provaremos uma fórmula do tipo Itô-Ventzel para caminhos Hölder cujo expoente é maior que 1/3. Os exemplos fundamentais de caminhos onde a fórmula é válida é o movimento Browniano fracionário. Nossa fórmula estende (e coincide) a versão clássica feita por H. Kunita na década de 80. As ferramentas utilizadas residem no contexto dos rough paths seguindo a abordagem de M. Gubinelli. Tais tecnicas começaram a serem desenvolvidas por T. Lyons no final de 90. Como aplicação, estudaremos equações diferenciais dirigidas por caminhos cujo expoente é maior que 1/2 (Sistemas de Young). Onde a idéia aqui é empregar nossa fórmula aplicando o método das caracteristicas nesse contexto, seguindo novamente os trabalhos de H. Kunita / Abstract: We prove an Itô-Ventezel type formula for Hölder paths with exponent is greater than 1/3. The most important class of examples of theses paths is given by fractional Brownian motion. Our formula is an extension (and agree) to classic version done by H. Kunita in 80's. The technical tools used rely on rough path theory following M. Gubinelli's approach. Those techniques were developed in the late 90's. by T. Lyons. As an application, we study differential equations driven by paths with exponent greater than 1/2 (Young Systems). The ideia here is to employ our formula together with method of characteristics in this setting, following Kunita's work / Doutorado / Matematica / Doutor em Matemática
210

Finding the right conditions for wind power : A business environment perspective on Sweden

Mårtensson, Andreas January 2012 (has links)
Mitigating the projections of climate change will require large investments in renewableenergy sources. In Sweden, a major share of new renewable energy production will have tocome from wind power. However, in 2009 wind power provided less than 2 percent of thecountry’s energy consumption.The main purpose of this thesis is to further the understanding of issues that affect thedevelopment of wind power in Sweden.The study has been carried out by qualitative interviews with five of the country’s leadingwind power developers. Duncan’s concept of external environment has been applied to definethe study and develop the interview questions.The study has resulted in the findings of eight key issues that affect the development of windpower in Sweden as well as areas in need of improvements from an investor’s perspective.Overall the thesis finds that wind power developers are very happy with the efforts from theSwedish government and the present conditions will likely allow wind power to have agrowing place in the Swedish energy system, provided that the current positive conditions are maintained.

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