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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.
181

A Dynamical System Approach for Resource-Constrained Mobile Robotics

Alam, Tauhidul 16 April 2018 (has links)
The revolution of autonomous vehicles has led to the development of robots with abundant sensors, actuators with many degrees of freedom, high-performance computing capabilities, and high-speed communication devices. These robots use a large volume of information from sensors to solve diverse problems. However, this usually leads to a significant modeling burden as well as excessive cost and computational requirements. Furthermore, in some scenarios, sophisticated sensors may not work precisely, the real-time processing power of a robot may be inadequate, the communication among robots may be impeded by natural or adversarial conditions, or the actuation control in a robot may be insubstantial. In these cases, we have to rely on simple robots with limited sensing and actuation, minimal onboard processing, moderate communication, and insufficient memory capacity. This reality motivates us to model simple robots such as bouncing and underactuated robots making use of the dynamical system techniques. In this dissertation, we propose a four-pronged approach for solving tasks in resource-constrained scenarios: 1) Combinatorial filters for bouncing robot localization; 2) Bouncing robot navigation and coverage; 3) Stochastic multi-robot patrolling; and 4) Deployment and planning of underactuated aquatic robots. First, we present a global localization method for a bouncing robot equipped with only a clock and contact sensors. Space-efficient and finite automata-based combinatorial filters are synthesized to solve the localization task by determining the robot’s pose (position and orientation) in its environment. Second, we propose a solution for navigation and coverage tasks using single or multiple bouncing robots. The proposed solution finds a navigation plan for a single bouncing robot from the robot’s initial pose to its goal pose with limited sensing. Probabilistic paths from several policies of the robot are combined artfully so that the actual coverage distribution can become as close as possible to a target coverage distribution. A joint trajectory for multiple bouncing robots to visit all the locations of an environment is incrementally generated. Third, a scalable method is proposed to find stochastic strategies for multi-robot patrolling under an adversarial and communication-constrained environment. Then, we evaluate the vulnerability of our patrolling policies by finding the probability of capturing an adversary for a location in our proposed patrolling scenarios. Finally, a data-driven deployment and planning approach is presented for the underactuated aquatic robots called drifters that creates the generalized flow pattern of the water, develops a Markov-chain based motion model, and studies the long- term behavior of a marine environment from a flow point-of-view. In a broad summary, our dynamical system approach is a unique solution to typical robotic tasks and opens a new paradigm for the modeling of simple robotics systems
182

Design Optimization of Frp Composite Panel Building Systems: Emergency Shelter Applications

Bradford, Nicholas M 24 August 2004 (has links)
Using advanced composites, an emergency shelter system has been designed. The system parameters are hurricane resistance to 138 mph wind velocity, simple erection, light weight, high durability and rapid construction. The project involves the solicitation of design proposals from several building system manufacturers and the development of an optimized emergency shelter system. The usage is well suited to pultruded members made from fiber reinforced polymers (FRP). Due to the anisotropic nature of FRP composites, a limited amount of research has been conducted to develop design optimization techniques for panels used in construction. This project allows for the development of optimization techniques for use in pultruded FRP panel members. The Project consisted of a detailed literature review conducted of emergency building industry to assess the validity of existing shelter systems, a state of the art review of connection design in FRP structures with an emphasis on non-standard types of connectors (ie...snap type), systemic structural optimization of emergency shelter for building geometry, roof configuration, foundation anchorage and building envelope, development of statistical methods for evaluation of viable existing emergency shelter systems. Subsequent to the initial phase of the investigation, an interlocking FRP composite panel system was developed. The system was analyzed for local buckling, first ply failure and global deflection criteria using modified equations originally developed for open section members. The results were verified using Finite Element Methods analysis software. The findings from the study indicate the need for a second phase in which the most promising available systems and the concept developed are fully tested to verify their capacity to withstand high wind forces including impact of wind borne debris.
183

A comparative study of mobile internet deployment models in New Zealand

Huang, Raymond Unknown Date (has links)
Internet services play an increasingly important role in modern society. Mobile Internet, a fast-growing technology that combines the Internet with mobile devices, has recently become popular. It is predicted that the convergence between mobile networks and the Internet would become the next generation of network architecture, and mobile IPv6 is likely to emerge as the most efficient and cost-effective instrument to achieve "anywhere and anytime" fast Internet and resolve the problems of worldwide mobility management. This research project reviews mobile Internet competition and the market mix in New Zealand, both major players and minor players being involved. The researcher also investigates the requirements of the mobile Internet deployment model from two perspectives: the market and the consumers. Finally the connection between end user services (for example, mobile Internet) and convergence (for example, network convergence and technology convergence) are examined in the research study conducted.The researcher applies a multi-case study strategy to conduct the research project and interview is adopted as the major research technique in order to collect research data. Several organizations which deploy mobile Internet services in New Zealand are chosen as participants, with the aim of offering both personal insights and business views to the research questions and objectives.
184

Simulation Study of a Semi-Dynamic AGV-Container Unit Job Deployment Scheme

Cheng, Yong Leong 01 1900 (has links)
Automated Guided Vehicle (AGV) Container-Job deployment is essentially a vehicle-dispatching problem. In this problem, the impact of vehicle dispatching polices on the ship makespan for discharging and/or loading operations is analyzed. In particular, given a storage location for each container to be discharged from the ship and given the current location of each container to be loaded onto the ship, the problem is to propose an efficient deployment scheme to dispatch vehicles to containers so as to minimize the makespan of the ship so as to increase the throughput. The makespan of the ship refers to the time a ship spends at the port for loading and unloading operations. In this paper, we will compare the performance of current deployment scheme used with the new proposed deployment scheme, both with deadlock prediction & avoidance algorithm done in previous study [1]. The prediction & avoidance algorithm predicts and avoids cyclic deadlock. The current deployment scheme, namely pmds makes use of a greedy heuristics which dispatches the available vehicle that will reach the quay with the minimum amount of time the vehicle has to spend waiting for the crane to discharge/load the container from/onto the ship. The new deployment scheme, namely mcf aims to formulate the problem as a minimum cost flow problem, which will then be solved by network simplex code. The two simulation models are implemented using discrete-event simulation software, AutoMod, and the performances of both deployment schemes are analyzed. The simulation results show that the new deployment scheme will result in a higher throughput and lower ship makespan than the current deployment scheme. / Singapore-MIT Alliance (SMA)
185

Optimering inför insats  : en idealtypsanalys av korvetten HMS Stockholm

Linell, Jan-Erik January 2009 (has links)
<p>I och med Försvarsmaktens omställning till insatsförsvar med internationella åtaganden har sannolikheten för att marina förband ska nyttjas för väpnad strid ökat markant. Med detta följer ett än större behov av att kunna hantera sådana prövningar. I den här uppsatsen provas idealtypsanalys som metod att mäta korvetten HMS Stockholms effektivitet ur ett organisationsteoretiskt perspektiv. Idealtypen, referensfartyget ”HMS Excellence”, skapas genom att använda 7s modellen (Waterman et al.) för att åskåda organisationen och resultat från den Amerikanska studien <em>”Excellence in the Surface Navy”</em> (Gullickson & Chenette) som indikatorer för effektivitet. Genom att presentera intervjudata från HMS Stockholm i samma dimensioner skapas ett underlag för analys.</p><p>Resultaten från uppsatsen visar att HMS Stockholm är ett effektivt stridsfartyg med vissa organisatoriska brister vars orsak kan spåras till intensiteten i pågående insatsförberedelser. Vidare visar analysen att 7s modellen har potential att vara ett användbart verktyg för att optimera ett stridsfartygs organisation samt som en komponent i idealtypsanalys.</p> / <p>Because of the Swedish Armed Forces reformation from an operational defense force to a rapid action force with international commitments the odds of naval units being involved in armed confrontation has distinctively increased. This leads to an even greater need for battle readiness. In this thesis ideal type analysis is tried as a method to assess the efficiency of the Swedish warship HMS Stockholm from an organization theoretical perspective. The ideal case, a reference war ship named HMS Excellence, is created by combining results from Gullickson & Chenettes study <em>Excellence in the Surface Navy, </em>with the 7s framework. HMS Stockholm is presented in the same manner combining interview data with the 7s framework. The difference between the ideal case and empirical case is used as a measurement of HMS Stockholm´s efficiency.</p><p>The author concludes that HMS Stockholm is an effective organization with an occasional weakness in the systems dimension due to the intensity of deployment preparations. Also, the author argues for ideal type analysis, using the 7s framework, as a tool to optimize deployment preparations and the 7s framework as a tool to optimize war ship organizations.</p>
186

Vita praeponitur : Livet främst

Ericsson, Johnny January 2006 (has links)
<p>En teoretisk kontroll av luftvärnsbataljonens sjukvårdsfunktion</p><p>Syftet med detta arbete är att inom ramen för funktionsmålsättning för Försvarsmaktens hälso- och sjukvård kontrollera om luftvärnsbataljonens sjukvårdsfunktion enligt org. 09 är korrekt dimensionerad.</p><p> Frågeställningen är: När, med hänsyn till grupperingsgeometri, medicinska tidskrav samt evakueringskapacitet blir sjukvårdsfunktionen en begränsande faktor för luftvärnsbataljonen.</p><p> För att svara på detta jämförs luftvärnsbataljonens TOEM med kraven ur funktionsmålsättning för Försvarsmaktens hälso- sjukvård i syfte att kontrollera om sjukvårdsfunktionen ges förutsättning att lösa ställda uppgifter. Vidare analyseras faktorerna, aktionsradie, förlustskadeberäkningar preventiv medicin, samt evakueringskapacitet och grupperingsgeometri.</p><p>Den viktigaste slutsatsen ur arbetet är: Det är inte sannolikt att samtliga enheter inom bataljonen kan åtnjuta möjligheten till adekvat sjukvård inom de tider som de medicinska kraven ställer.</p> / <p>The purpose of this essay is to investigate if the medical function in the Air Defence Battalion is enough.</p><p> The question to be answered in this essay is as follows: When, considering deployment geometry, medical time-demands and evacuation capacity does the medical function become a limiting factor for the AD Battalion?</p><p> A descriptive method is used in this essay. Material has been gathered and analysed to show the limitations of the battalion considering the medical function. A study has also been made. The material and the study are used as a base in the discussion and from the discussion and the results from the analysis, conclusions are drawn.</p><p>One of these conclusions is that: It is not probable that all units in the Air Defence Battalion will receive proper medical attention within the time-span established in the guiding medical documents.</p>
187

Performance Analysis and Deployment Techniques forWireless Sensor Networks

She, Huimin January 2012 (has links)
Recently, wireless sensor network (WSN) has become a promising technology with a wide range of applications such as supply chain monitoring and environment surveillance. It is typically composed of multiple tiny devices equipped with limited sensing, computing and wireless communication capabilities. Design of such networks presents several technique challenges while dealing with various requirements and diverse constraints. Performance analysis and deployment techniquesare required to provide insight on design parameters and system behaviors. Based on network calculus, a deterministic analysis method is presented for evaluating the worst-case delay and buffer cost of sensor networks. To this end,traffic splitting and multiplexing models are proposed and their delay and buffer bounds are derived. These models can be used in combination to characterize complex traffic flowing scenarios. Furthermore, the method integrates a variable duty cycle to allow the sensor nodes to operate at low rates thus saving power. In an attempt to balance traffic load and improve resource utilization and performance,traffic splitting mechanisms are introduced for sensor networks with general topologies. To provide reliable data delivery in sensor networks, retransmission has been one of the most popular schemes. We propose an analytical method to evaluate the maximum data transmission delay and energy consumption of two types of retransmission schemes: hop-by-hop retransmission and end-to-end retransmission.In order to validate the tightness of the bounds obtained by the analysis method, the simulation results and analytical results are compared with various input traffic loads. The results show that the analytic bounds are correct and tight. Stochastic network calculus has been developed as a useful tool for Qualityof Service (QoS) analysis of wireless networks. We propose a stochastic servicecurve model for the Rayleigh fading channel and then provide formulas to derive the probabilistic delay and backlog bounds in the cases of deterministic and stochastic arrival curves. The simulation results verify that the tightness of the bounds are good. Moreover, a detailed mechanism for bandwidth estimation of random wireless channels is developed. The bandwidth is derived from the measurement of statistical backlogs based on probe packet trains. It is expressed by statistical service curves that are allowed to violate a service guarantee with a certain probability. The theoretic foundation and the detailed step-by-step procedure of the estimation method are presented. One fundamental application of WSNs is event detection in a Field of Interest(FoI), where a set of sensors are deployed to monitor any ongoing events. To satisfy a certain level of detection quality in such applications, it is desirable that events in the region can be detected by a required number of sensors. Hence, an important problem is how to conduct sensor deployment for achieving certain coverage requirements. In this thesis, a probabilistic event coverage analysis methodis proposed for evaluating the coverage performance of heterogeneous sensor networks with randomly deployed sensors and stochastic event occurrences. Moreover,we present a framework for analyzing node deployment schemes in terms of three performance metrics: coverage, lifetime, and cost. The method can be used to evaluate the benefits and trade-offs of different deployment schemes and thus provide guidelines for network designers. / <p>QC 20120906</p>
188

Efficient Detection on Stochastic Faults in PLC Based Automated Assembly Systems With Novel Sensor Deployment and Diagnoser Design

Wu, Zhenhua 2012 May 1900 (has links)
In this dissertation, we proposed solutions on novel sensor deployment and diagnoser design to efficiently detect stochastic faults in PLC based automated systems First, a fuzzy quantitative graph based sensor deployment was called upon to model cause-effect relationship between faults and sensors. Analytic hierarchy process (AHP) was used to aggregate the heterogeneous properties between sensors and faults into single edge values in fuzzy graph, thus quantitatively determining the fault detectability. An appropriate multiple objective model was set up to minimize fault unobservability and cost while achieving required detectability performance. Lexicographical mixed integer linear programming and greedy search were respectively used to optimize the model, thus assigning the sensors to faults. Second, a diagnoser based on real time fuzzy Petri net (RTFPN) was proposed to detect faults in discrete manufacturing systems. It used the real time PN to model the manufacturing plant while using fuzzy PN to isolate the faults. It has the capability of handling uncertainties and including industry knowledge to diagnose faults. The proposed approach was implemented using Visual Basic, and tested as well as validated on a dual robot arm. Finally, the proposed sensor deployment approach and diagnoser were comprehensively evaluated based on design of experiment techniques. Two-stage statistical analysis including analysis of variance (ANOVA) and least significance difference (LSD) were conducted to evaluate the diagnosis performance including positive detection rate, false alarm, accuracy and detect delay. It illustrated the proposed approaches have better performance on those evaluation metrics. The major contributions of this research include the following aspects: (1) a novel fuzzy quantitative graph based sensor deployment approach handling sensor heterogeneity, and optimizing multiple objectives based on lexicographical integer linear programming and greedy algorithm, respectively. A case study on a five tank system showed that system detectability was improved from the approach of signed directed graph's 0.62 to the proposed approach's 0.70. The other case study on a dual robot arm also show improvement on system's detectability improved from the approach of signed directed graph's 0.61 to the proposed approach's 0.65. (2) A novel real time fuzzy Petri net diagnoser was used to remedy nonsynchronization and integrate useful but incomplete knowledge for diagnosis purpose. The third case study on a dual robot arm shows that the diagnoser can achieve a high detection accuracy of 93% and maximum detection delay of eight steps. (3) The comprehensive evaluation approach can be referenced by other diagnosis systems' design, optimization and evaluation.
189

Optimering inför insats  : en idealtypsanalys av korvetten HMS Stockholm

Linell, Jan-Erik January 2009 (has links)
I och med Försvarsmaktens omställning till insatsförsvar med internationella åtaganden har sannolikheten för att marina förband ska nyttjas för väpnad strid ökat markant. Med detta följer ett än större behov av att kunna hantera sådana prövningar. I den här uppsatsen provas idealtypsanalys som metod att mäta korvetten HMS Stockholms effektivitet ur ett organisationsteoretiskt perspektiv. Idealtypen, referensfartyget ”HMS Excellence”, skapas genom att använda 7s modellen (Waterman et al.) för att åskåda organisationen och resultat från den Amerikanska studien ”Excellence in the Surface Navy” (Gullickson &amp; Chenette) som indikatorer för effektivitet. Genom att presentera intervjudata från HMS Stockholm i samma dimensioner skapas ett underlag för analys. Resultaten från uppsatsen visar att HMS Stockholm är ett effektivt stridsfartyg med vissa organisatoriska brister vars orsak kan spåras till intensiteten i pågående insatsförberedelser. Vidare visar analysen att 7s modellen har potential att vara ett användbart verktyg för att optimera ett stridsfartygs organisation samt som en komponent i idealtypsanalys. / Because of the Swedish Armed Forces reformation from an operational defense force to a rapid action force with international commitments the odds of naval units being involved in armed confrontation has distinctively increased. This leads to an even greater need for battle readiness. In this thesis ideal type analysis is tried as a method to assess the efficiency of the Swedish warship HMS Stockholm from an organization theoretical perspective. The ideal case, a reference war ship named HMS Excellence, is created by combining results from Gullickson &amp; Chenettes study Excellence in the Surface Navy, with the 7s framework. HMS Stockholm is presented in the same manner combining interview data with the 7s framework. The difference between the ideal case and empirical case is used as a measurement of HMS Stockholm´s efficiency. The author concludes that HMS Stockholm is an effective organization with an occasional weakness in the systems dimension due to the intensity of deployment preparations. Also, the author argues for ideal type analysis, using the 7s framework, as a tool to optimize deployment preparations and the 7s framework as a tool to optimize war ship organizations.
190

Vita praeponitur : Livet främst

Ericsson, Johnny January 2006 (has links)
En teoretisk kontroll av luftvärnsbataljonens sjukvårdsfunktion Syftet med detta arbete är att inom ramen för funktionsmålsättning för Försvarsmaktens hälso- och sjukvård kontrollera om luftvärnsbataljonens sjukvårdsfunktion enligt org. 09 är korrekt dimensionerad.  Frågeställningen är: När, med hänsyn till grupperingsgeometri, medicinska tidskrav samt evakueringskapacitet blir sjukvårdsfunktionen en begränsande faktor för luftvärnsbataljonen.  För att svara på detta jämförs luftvärnsbataljonens TOEM med kraven ur funktionsmålsättning för Försvarsmaktens hälso- sjukvård i syfte att kontrollera om sjukvårdsfunktionen ges förutsättning att lösa ställda uppgifter. Vidare analyseras faktorerna, aktionsradie, förlustskadeberäkningar preventiv medicin, samt evakueringskapacitet och grupperingsgeometri. Den viktigaste slutsatsen ur arbetet är: Det är inte sannolikt att samtliga enheter inom bataljonen kan åtnjuta möjligheten till adekvat sjukvård inom de tider som de medicinska kraven ställer. / The purpose of this essay is to investigate if the medical function in the Air Defence Battalion is enough.  The question to be answered in this essay is as follows: When, considering deployment geometry, medical time-demands and evacuation capacity does the medical function become a limiting factor for the AD Battalion?  A descriptive method is used in this essay. Material has been gathered and analysed to show the limitations of the battalion considering the medical function. A study has also been made. The material and the study are used as a base in the discussion and from the discussion and the results from the analysis, conclusions are drawn. One of these conclusions is that: It is not probable that all units in the Air Defence Battalion will receive proper medical attention within the time-span established in the guiding medical documents.

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