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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.

Straight-line Coverage in Wireless Sensor Networks

Lee, Tzu-Chen 17 July 2006 (has links)
Wireless sensor networks provide an alternative way of improving our environments, such as environment surveillance, hazard monitoring, and other customized environment application, especially in military applications. Furthermore, the coverage issue in wireless sensor networks also plays an important role. Good coverage of a sensor network is an essential issue to ensure the quality of service. This paper studies the barrier coverage problems of a sensor networks, and will find the optimized straight-line path for both best-case and worst-case coverage problems. The optimal algorithm we proposed has a quadratic time complexity and is based on computational geometry. We proposed the distance function theory and applied it in our problems and we used the sweep and divide concept to solve the problems. Furthermore, the correctness of the proposed method is validated and simulated by experiments.

Multi-Agent Area Coverage Control Using Reinforcement Learning Techniques

Adepegba, Adekunle Akinpelu January 2016 (has links)
An area coverage control law in cooperation with reinforcement learning techniques is proposed for deploying multiple autonomous agents in a two-dimensional planar area. A scalar field characterizes the risk density in the area to be covered yielding nonuniform distribution of agents while providing optimal coverage. This problem has traditionally been addressed in the literature to date using locational optimization and gradient descent techniques, as well as proportional and proportional-derivative controllers. In most cases, agents' actuator energy required to drive them in optimal configurations in the workspace is not considered. Here the maximum coverage is achieved with minimum actuator energy required by each agent. Similar to existing coverage control techniques, the proposed algorithm takes into consideration time-varying risk density. These density functions represent the probability of an event occurring (e.g., the presence of an intruding target) at a certain location or point in the workspace indicating where the agents should be located. To this end, a coverage control algorithm using reinforcement learning that moves the team of mobile agents so as to provide optimal coverage given the density functions as they evolve over time is being proposed. Area coverage is modeled using Centroidal Voronoi Tessellation (CVT) governed by agents. Based on [1,2] and [3], the application of Centroidal Voronoi tessellation is extended to a dynamic changing harbour-like environment. The proposed multi-agent area coverage control law in conjunction with reinforcement learning techniques is implemented in a distributed manner whereby the multi-agent team only need to access information from adjacent agents while simultaneously providing dynamic target surveillance for single and multiple targets and feedback control of the environment. This distributed approach describes how automatic flocking behaviour of a team of mobile agents can be achieved by leveraging the geometrical properties of centroidal Voronoi tessellation in area coverage control while enabling multiple targets tracking without the need of consensus between individual agents. Agent deployment using a time-varying density model is being introduced which is a function of the position of some unknown targets in the environment. A nonlinear derivative of the error coverage function is formulated based on the single-integrator agent dynamics. The agent, aware of its local coverage control condition, learns a value function online while leveraging the same from its neighbours. Moreover, a novel computational adaptive optimal control methodology based on work by [4] is proposed that employs the approximate dynamic programming technique online to iteratively solve the algebraic Riccati equation with completely unknown system dynamics as a solution to linear quadratic regulator problem. Furthermore, an online tuning adaptive optimal control algorithm is implemented using an actor-critic neural network recursive least-squares solution framework. The work in this thesis illustrates that reinforcement learning-based techniques can be successfully applied to non-uniform coverage control. Research combining non-uniform coverage control with reinforcement learning techniques is still at an embryonic stage and several limitations exist. Theoretical results are benchmarked and validated with related works in area coverage control through a set of computer simulations where multiple agents are able to deploy themselves, thus paving the way for efficient distributed Voronoi coverage control problems.

Preframe techniques in constructive locale theory

Townsend, Christopher Francis January 1996 (has links)
No description available.

Flower constellation optimization and implementation

Bruccoleri, Christian 15 May 2009 (has links)
Satellite constellations provide the infrastructure to implement some of the most important global services of our times both in civilian and military applications, ranging from telecommunications to global positioning, and to observation systems. Flower Constellations constitute a set of satellite constellations characterized by periodic dynamics. They have been introduced while trying to augment the existing design methodologies for satellite constellations. The dynamics of a Flower Constellation identify a set of implicit rotating reference frames on which the satellites follow the same closed-loop relative trajectory. In particular, when one of these rotating reference frames is “Planet Centered, Planet Fixed”, then all the orbits become compatible (or resonant) with the planet; consequently, the projection of the relative path on the planet results in a repeating ground track. The satellite constellations design methodology currently most utilized is the Walker Delta Pattern or, more generally, Walker Constellations. The set of orbital planes and initial spacecraft positions are represented by a set of only three integers and two real parameters rather than by all the orbital elements; Flower Constellations provide a more general framework in which most of the former restrictions are removed, by allowing the use of resonant elliptical orbits. Flower Constellations can represent hundreds of spacecraft with a set of 6 integers and 5 real parameters only and existing constellations can be easily reproduced. How to design a Flower Constellation to satisfy specific mission requirements is an important problem for promoting the acceptance of this novel concept by the space community. Therefore one of the main goals of this work is that of proposing design techniques that can be applied to satisfy practical mission requirements. The results obtained by applying Global optimization techniques, such as Genetic Algorithms, to some relevant navigation and Earth observation space-based systems show that the Flower Constellations not only are as effective asWalker Constellations, but can also be applied to non-traditional constellation problem domains, such as regional coverage and reconnaissance.

The Study of the Relationship Among the Crisis Incident of the Enterprise and News Coverage

Tu, Chiu-ching 15 August 2006 (has links)
The purpose of this study is focused on The Study of the Relationship Among the Crisis Incident of the Enterprise and News Coverage. The Content report analysis and semi-structured interviews were adopted in the study. In the Content report analysis,the samples were come from HANSHIN Department Store¡BGRAND HI-LAI Hotel and Kaohsinug Pacific SOGO Department Store. This study was used Semi-structured interviews for further investigation from 3 business¡¦s PR related personnel and 4 different planes media reporter. Therefore,7 persons were interviewed for this study. The following results were derived: Business owner and the media rechallenges the ordinary familiar outside person, the matter, the thing, the environment, the variable which the increase crisis links up.otherwises, The benefit sponsor's role possibly turns the key which the danger thing sends, The crisis cause existence is indefinite, cause troubles the status to form the migration -like trend, also changes the crisis already to have condition, presents the mobilized development. Reporter and the news originate the interaction relates into the parallel pattern, the strengthening "the scene principle" report.And the picture has become various media competition new stage, Gradually substitutes for the frame news fact another tool. The news originates the multiplication, the information czar's phenomenon gradually blurs. Eventually, this study was concluded the valuable analyzed results and also provide the references for business¡BPR and the future investigation. Keywords¡GCrisis Incident¡ANews Coverage

Magazine coverage of breast cancer in 1993 and 2003: a qualitative content analysis

Reyes, Naomi Louise 29 August 2005 (has links)
Breast cancer has touched the lives of countless people, yet many women have misconceptions about the disease. One of the most common sources for breast cancer information used by American women is popular magazines. The current study sought to describe the content of magazine articles on breast cancer from 1993 and 2003 in an attempt to determine whether article content differed, and if so, in what ways and for what reasons. Topical theme, identification of risk factors, preventive measures, and sources mentioned were categories developed to determine possible differences in content between the two years. Twice as many articles on breast cancer appeared in 1993 as in 2003. In 1993, living with breast cancer was a theme of many articles, while in 2003, hormone replacement therapy was a dominant theme. Family history was emphasized as a risk factor in articles from 1993, while long-term hormone-replacement therapy was emphasized in 2003. In general, articles in 2003 focused on overall health practices in the possible prevention of breast cancer. Social, political, and scientific occurrences relating to breast cancer that took place from the early 1990s through 2003 were considered when analyzing content. Most of the differences in content appeared to reflect such occurrences.

The Hajj : past, present and future : the communication aspect

al-Ken, Akeel Ibrahim January 1995 (has links)
It is the aim of this thesis to investigate the work of the Saudi Arabian media and the information services in relation to the Hajj, to examine their policies, procedures and problems faced by them, and to propose solutions and improvements. The basic objective of this study during the Hajj is to examine how the Saudi Arabian media can serve more effectively the needs of the pilgrims, with their different cultures and languages. An historical examination of the evolution of the Hajj, the services and the media form the background and context for the examination of the current position. The following research methods were adopted: 1- Group discussions and interviews were carried out amongsts ome of the Islamic media visiting the Hajj in order to highlight any problems and concerns about the work of the Saudi Arabian media during the Hajj. 2- A content analysis of the Saudi Arabian newspapers during the Hajj season was carried out using a quota sampling procedure. In total 434 articles were studied using nine coding categories. 3- The content and form of Saudi Arabian radio and television programmes, Hajj handbooks,cassettes and video tapes provided for the pilgrims were analysed. 4- The daily routine of the average pilgrim during the 1993 Hajj season was observed. This work is divided into eight chapters. The Introduction (Chapter One) covers a statement of the problems, aims of the study and gives the various sources of information. In Chapter Two the historical background of the city of Mecca and the Kaaba is discussed, thus providing the historical aspects of the Hajj. The Saudi Arabian Royal Family and the Hajj are discussedin Chapter Three with respect to the importance of the Hajj as a religious obligation. Chapter Four examines the present Saudi Arabian official Hajj policy and procedures, the ministries and committees administering the Hajj and their terms of reference, and specific problems related to the Muslim calendar, weather, transport, accommodation, food, health, and security. Chapter Five is' devoted to the development of the Saudi Arabian media and their coverage of the Hau. Chapter Six analyses the problems which face the Saudi Arabian media during the Hai. Chapter Seven deals with proposed solutions. Finally, conclusions are presented regarding the main features of the present communication systems with regard to the coverage of the Hajj. There are nine major findings in this study: 1- Much has been written on the history of the two Holy cities of Mecca and al-Madina and Arabia's Hajj before and under the Islam, but little attention has been paid to the communication aspects of information and instruction available to the pilgrims. 2- The Saudi Arabian media strives to cater for all the pilgrims during their Haij. 3- The Pilgrims, however need more and better targeted information before, as well as after, their arrival in Saudi Arabia. 4- Most of the pilgrims have no radio or television sets in their buildings and so they are not directly exposed to Saudi Arabian Information. 5- The Saudi Arabian Hajj newspapers provide special information supplements, but these are not as effective as had been hoped. 6- The Islamic media delegation which visit Saudi Arabia during the Hajj believes that the Saudi Arabian media does not serve the pilgrims from different cultures adequately as there is a lack of programme targeting and a shortage of information for non arabic speaking pilgrims. 7- The Saudi Arabian television channels are unable, as yet, to provide services in the main pilgrims' languages, but new technologies should be able to redress this. 8- The Saudi Arabian Radio and TV stations need better scheduling. 9- No systematic study has yet been carried out about the pilgrims' attitudes, their daily movements, access and reaction to the Saudi Arabian Media during the Hail: such a study should form the basis of future media and information policies.

Use of Double Anaerobic Coverage and its Implications

Gomez, Eddie, Shinde, Gaurav, Patel, Niyat, Matthias, Kathyrn, Nix, David January 2013 (has links)
Class of 2013 Abstract / Specific Aims: Metronidazole and clindamycin can be prescribed for anaerobic infections; however, patients are periodically prescribed a second agent with duplicate anaerobic coverage. The purpose of this project was to evaluate the frequency, appropriateness, and potential consequences of combination therapy against anaerobic organisms in patients prescribed metronidazole or clindamycin. Methods: In this IRB approved project, adult patients who were prescribed either intravenous metronidazole or intravenous clindamycin with or without another agent with anaerobic coverage for at least 48 hours at an academic medical center between May 2010 and April 2012 were evaluated. Subjects were excluded if documented Clostridium difficile associated diarrhea within 14 days prior to intravenous metronidazole, if use of oral vancomycin within 14 days prior to intravenous metronidazole, or if presence of diarrhea with more than six unformed stools 48 hours prior to intravenous metronidazole. Data collected includes demographic information, site of infection, surgical interventions, antibiotic therapy prescribed, therapy outcomes, and reported adverse events. The odds ratio for combination anti-anaerobic therapy was calculated for metronidazole and clindamycin. The appropriateness of combination anaerobic coverage therapy was evaluated based on expert opinion and guideline statements. The frequency of potential complications such as adverse drug events, Clostridium difficile infection, other diarrheal illness and superinfections associated with enteric organisms within 30 days after starting anaerobic therapy will be reported Main Results: In Progress Conclusion: To be determined

Sensor Deployment and Coverage Maintenance by a Team of Robots

Li, Qiao January 2015 (has links)
Wireless sensor and robot networks (WSRNs) are an integration of wireless sensor network (WSNs) and multi-robot systems. They comprise of networked sensor and mobile robots that communicate via wireless links to perform distributed sensing and actuation tasks in a region of interest (ROI). In addition to gathering and reporting data from the environment, sensors may also report failures of neighboring sensors or lack of coverage in certain neighborhood to nearby mobile robot. Once an event has been detected, robots coordinate with each other to make a decision on the most appropriate way to perform the action. Coverage can be established and improved in different ways in wireless sensor and robot networks. Initial random sensor placement, if applied, may be improved via robot-assisted sensor relocation or additional placement. One or more robots may carry sensors and move within the ROI; while traveling, they drop sensors at proper positions to construct desired coverage. Robots may relocate and place spare sensors according to certain energy optimality criteria. This thesis proposes a solution, which we call Election-Based Deployment (EBD), for simultaneous sensor deployment and coverage maintenance in multi-robot scenario in failure-prone environment. To our knowledge, it is the first carrier-based localized algorithm that is able to achieve 100% coverage of the ROI with multiple robots in failure-prone environment since it combines both sensor deployment and coverage maintenance process. We can observe from the simulation results that EBD outperforms the existing algorithms and balances the workload of robots while reducing the communication overhead to a great extent.

Equity, access and utilisation in the state-funded universal insurance scheme (RSBY/MSBY) in Chhattisgarh State, India: What are the implications for Universal Health Coverage?

Nandi, Sulakshana January 2019 (has links)
Philosophiae Doctor - PhD / Universal Health Coverage (UHC) has provided the impetus for the introduction of publicly-funded health insurance (PFHI) schemes, involving the private sector, especially in low-and middle-income countries with mixed health systems. Although equity is considered as being core to UHC, the implication of UHC interventions for equity in access (availability, affordability and acceptability) beyond financial protection is inadequately researched. India introduced a national PFHI scheme (Rashtriya Swasthya Bima Yojana) in 2007 which has since then been expanded considerably through the Pradhan Mantri Jan Aarogya Yojana (PMJAY) scheme. However, contestation remains as to whether PFHI schemes are the most appropriate interventions for UHC in India. Evidence so far provides cause for concern regarding their impact on financial protection and health equity. With PFHI schemes burgeoning globally, there is an urgent need for a holistic understanding of the pathways of impact of these schemes, including their roles in promoting equity of access and achievement of UHC objectives. The state-funded universal health insurance scheme (RSBY/MSBY) in Chhattisgarh State provided the opportunity to explore these pathways of impact, especially on vulnerable communities, as the State has a universal health insurance scheme. This PhD aims to study equity, access and utilisation in the state-funded universal insurance scheme in Chhattisgarh State of India, in the context of Universal Health Coverage. It is presented as a thesis by publications.

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