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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.
561

Indoor robot localization and collaboration

Zaharans, Eriks January 2013 (has links)
The purpose of this thesis is to create an indoor rescue scenario with multiple self-localizing robots that are able to collaborate for a victim search. Victims are represented by RFID tags and detecting them combined with an accurate enough location data is considered as a successful finding. This setup is created for use in a laboratory assignment at Linköping University. We consider the indoor localization problem by trying to use as few sensors as possible and implement three indoor localization methods - odometry based, passive RFID based, and our approach by fusing both sensor data with particle filter.The Results show that particle filter based localization performs the best in comparison to the two other implemented methods and satisfies the accuracy requirements stated for the scenario. The victim search problem is solved by an ant mobility (pheromone-based) approach which integrates our localization method and provides a collaborative navigation through the rescue area. The purpose of the pheromone mobility approach is to achieve a high coverage with an acceptable resource consumption.Experiments show that area is covered with approximately 30-40% overhead in traveled distance comparing to an optimal path.
562

A macroeconomic study of the costs, consequences and policy implications of sectorial labour reallocation

Tapp, Stephen S. 14 August 2008 (has links)
This thesis uses a macroeconomic approach to study labour adjustments following sector-specific shocks. I develop a general model, investigate its dynamic adjustment process and apply it to study the Canadian economy in 2002–2006. This episode is an interesting case study because it features a significant labour reallocation to the resource sector and away from manufacturing, precipitated by an increase in global commodity prices and an associated exchange rate appreciation. The results establish that impediments to the adjustment process are economically significant in the aggregate for this episode, imposing costs of up to three percent of output during the transition. These findings augment several studies that suggest individual workers can face large and persistent earnings losses during job turnover. However, unlike previous research, I use the search and matching approach — which incorporates explicit labour market frictions — to uncover the sources of these costs for the macroeconomy. The findings emphasize that job loss itself is not particularly important quantitatively, but rather the non-transferability of skills during job turnover is a key concern. Finally, I investigate how labour market policy impacts the economy’s response to sector-specific shocks by analyzing a counterfactual policy change in unemployment benefits and improved skill acquisition through faster learning and training subsidies. The results reveal interesting policy trade-offs. First, I find that increasing unemployment benefits prolongs the economy’s adjustment, reduces employment, output and welfare and increases unemployment incidence and duration. However, because this policy impacts high-productivity and low-productivity sectors differently, it shifts the composition of the remaining jobs towards high-productivity sectors, thereby raising aggregate productivity and also reduces wage inequality. Second, I find that faster skill acquisition has the potential to deliver large economic gains in the long-run, but requires up-front investment costs which entail reduced economic performance in the short-run. / Thesis (Ph.D, Economics) -- Queen's University, 2008-08-05 23:44:39.827
563

The role of primate superior colliculus in naturalistic visual search behavior

SHEN, KELLY 22 December 2010 (has links)
Primates, including humans, explore their visual environment with sequences of gaze fixations interrupted by saccadic eye movements that re-orient the fovea to objects of interest. This visual behavior is thought to involve two separate processes. First, the current foveal image is analyzed and the next object of interest is selected as a saccade target. Second, previously examined objects are retained to prevent their re-examination. Visual behavior has been studied successfully using the visual search paradigm, in which subjects locate a unique target stimulus from amongst multiple distracting stimuli. Models of visual search posit that the process of saccade target selection is guided by a visual salience map. This map receives both stimulus-driven and goal-directed inputs to form representations of visual objects, and a competition between those representations is played out to determine the next saccade target. Neurophysiological studies using nonhuman primates have suggested that the salience map is distributed across a network of brain areas that includes the midbrain superior colliculus (SC). These studies, however, have not ruled out the possibility that selective activity for a saccade target may instead be related to the preparation of the saccade. Moreover, not much is known about the selection of a saccade target beyond the first in a sequence of gaze fixations. Finally, the mechanisms underlying the process of saccade target retention are not well understood. In this thesis, I will investigate the role of the primate SC in visual behavior by recording the activity of single neurons while monkeys perform visual search tasks. The major findings will describe 1) how SC sensory-motor neurons instantiate the visual salience map; 2) how this salience map is dynamically updated so that saccade targets are retained; and 3) how multiple representations on this salience map are processed in parallel for saccade target selection. Given SC’s role in the control of visual behavior and its position within the network involved in cognitive processes, these findings have important implications for our understanding of the neural basis of human cognition and of its dysfunctions in disease states. / Thesis (Ph.D, Neuroscience Studies) -- Queen's University, 2010-12-22 09:52:20.143
564

Reinforcement Learning and Simulation-Based Search in Computer Go

Silver, David Unknown Date
No description available.
565

Text Document Topical Recursive Clustering and Automatic Labeling of a Hierarchy of Document Clusters

Li, Xiaoxiao Unknown Date
No description available.
566

Performance Improvement of ED at VGH Using Simulation and Optimization

Zhao, Yuancheng 15 September 2013 (has links)
Emergency department(ED) is one of the busiest clinical units in Winnipeg Victoria Gen-eral Hospital (VGH) which faces the challenge of patients’ long waiting-time as increas-ing healthcare demand and limited resources. This research investigates the critical factors of the ED operation to enhance the operational efficiency using simulation modeling and optimization. The contribution of this research is the integration of simulation and optimization for the performance improvement of ED operations. Discrete-events simula-tion (DES) methodology provides a cost-effective tool to analyse the performance of the ED operations and evaluates the potential alternatives. Design of experiments (DOE) and Scatter search (SS) of model optimization are proposed to search the ED potential capaci-ty for waiting-time reduction. The patient-flow is accelerated along with the waiting-time reduction, which results in better efficient patient throughput in the ED. A specific strate-gy is suggested to improve the ED operation based on the simulation model.
567

Ruošinių realizacijos optimizavimo procedūrų sudarymas ir tyrimas / Creation and research optimization of blank realization procedures

Šidla, Donatas 30 May 2004 (has links)
The object of Master Thesis is the creation and research optimization of blank realization procedures. Four main parts comprise the thesis: analysis of the problem, theoretical solutions, research and outcomes, conclusions and recommendations. Optimization methods, their advantages and limitations have been analyzed in the first part. The most appropriate optimization method for problem solving was selected. Designed optimization methods have been presented in the theoretical solutions part: exhaustive search, tabu search and a new one, presented by the author. A program was created for comparison of these methods. In the third part of the thesis outcomes of the research are presented. Designed methods were tested and compared by their routes length, process time, computations duration and other parameters. Conclusions of the thesis and recommendations for implementation of analyzed procedures have been presented in the part of conclusions. Literature in Lithuanian, English was used in preparing the thesis. There are 19 tables and 29 pictures in the thesis.
568

Būsimų studentų paieškos ir motyvavimo studijuoti Šiaulių universitete organizavimas / Organization of the search of prospective students and study motivation at Siauliai University

Liolytė, Dalia 01 June 2005 (has links)
Organization peculiarities and problems of the search of prospective students and study motivation at Siauliai University have been framed and evaluated in Master thesis; strong and weak angles of Siauliai University performance in the areas of the search and motivation have been highlighted. Both theoretical and practical researches of different Lithuanian and foreign authors have been analyzed and systematized. Performed research has partly confirmed the hypotheses framed by the authors that the search of prospective students at Siauliai University is not the area of major importance as all places intended for students are naturally taken up and that major factors which in most cases influenced students to choose Siauliai University for their studies are an attractive study curriculum and convenient geographical position; consequently, most of the students from Siauliai and its region chose this particular university.
569

Dynamic Models of Human Capital Investment

Ashworth, Jared January 2015 (has links)
<p>My dissertation examines human capital investments and their role in individual's labor market outcomes. Chapter 2 analyzes how public school teachers decide to make human capital investments and the effects that these decisions have on their future labor market outcomes. In particular, I look at the decisions of employed teachers to obtain an advanced degree. Teachers' education and career decisions are modeled via a dynamic framework in the presence of teacher-specific unobserved heterogeneity. I find that teachers' decisions to obtain master's degrees are motivated by more than just an increase in salary. In particular, I observe teachers with master's degrees receiving a better draw on job characteristics, as measured by school quality, and that teachers are willing to pay between $1,500 and $20,000 to to move up one quartile in school quality. I also find that teachers value having broad access to online degree programs more than they dislike tuition costs. Counterfactual simulations by unobserved ability are consistent with a story that high-type teachers value both the salary increase and a better draw in career prospects, whereas low-type teachers are mostly interested in the salary increase.</p><p>Chapter 3 investigates the evolution over the last two decades in the wage returns to schooling and early work experience. Using data from the 1979 and 1997 panels of the National Longitudinal Survey of Youth, we isolate changes in skill prices from changes in composition by estimating a dynamic model of schooling and work decisions. Importantly, this allows us to account for the endogenous nature of the changes in educational and accumulated work experience over this time period. We find an increase over this period in the returns to working in high school, but a decrease in the returns to working while in college. We also find an increase in the incidence of working in college, but that any detrimental impact of in-college work experience is offset by changes in other observable characteristics. Overall, our decomposition of the evolution in skill premia suggests that both price and composition effects play an important role. The role of unobserved ability is also important.</p> / Dissertation
570

Computing stable models of logic programs

Singhi, Soumya 01 January 2003 (has links)
Solution of any search problem lies in its search space. A search is a systematic examination of candidate solutions of a search problem. In this thesis, we present a search heuristic that we can cr-smodels. cr-smodels prunes the search space to quickly reach to the solution of a problem. The idea is to pick an atom for branching , that lowers the growth rate of the linear recurrence and thuse, minimizes the remaining search space. Our goal in developing cr-smodels is to develop a search heuristic that is efficient on a wide range of problems. Then, we test cr-smodels over a wide range of randomly generated benchmarks. we observed that often randomly generated graphs with no Hamiltonian cycle were trivial to solve. Since, Hamiltonian cycle is an important benchmark problem, my other goal is to develop techniques that generate hard instances of graphs with no Hamiltonian cycle.

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