You limited your search to:

  Partner: UNT Libraries
 Department: Department of Electrical Engineering
 Collection: UNT Theses and Dissertations
Employment of dual frequency excitation method to improve the accuracy of an optical current sensor, by measuring both current and temperature.

Employment of dual frequency excitation method to improve the accuracy of an optical current sensor, by measuring both current and temperature.

Date: December 2008
Creator: Karri, Avinash
Description: Optical current sensors (OCSs) are initially developed to measure relatively large current over a wide range of frequency band. They are also used as protective devices in the event a fault occurs due to a short circuit, in the power generation and distribution industries. The basic principal used in OCS is the Faraday effect. When a light guiding faraday medium is placed in a magnetic field which is produced by the current flowing in the conductor around the magnetic core, the plane of polarization of the linearly polarized light is rotated. The angle of rotation is proportional to the magnetic field strength, proportionality constant and the interaction length. The proportionality constant is the Verdet constant V (λ, T), which is dependent on both temperature and wavelength of the light. Opto electrical methods are used to measure the angle of rotation of the polarization plane. By measuring the angle the current flowing in the current carrying conductor can be calculated. But the accuracy of the OCS is lost of the angle of rotation of the polarization plane is dependent on the Verdet constant, apart from the magnetic field strength. As temperature increases the Verdet constant decreases, so the angle of rotation ...
Contributing Partner: UNT Libraries
Comparison of source diversity and channel diversity methods on symmetric and fading channels.

Comparison of source diversity and channel diversity methods on symmetric and fading channels.

Date: August 2009
Creator: Li, Li
Description: Channel diversity techniques are effective ways to combat channel fading and noise in communication systems. In this thesis, I compare the performance of source and channel diversity techniques on fading and symmetric continuous channels. My experiments suggest that when SNR is low, channel diversity performs better, and when SNR is high, source diversity shows better performance than channel diversity.
Contributing Partner: UNT Libraries
Integrating environmental data acquisition and low cost Wi-Fi data communication.

Integrating environmental data acquisition and low cost Wi-Fi data communication.

Date: December 2009
Creator: Gurung, Sanjaya
Description: This thesis describes environmental data collection and transmission from the field to a server using Wi-Fi. Also discussed are components, radio wave propagation, received power calculations, and throughput tests. Measured receive power resulted close to calculated and simulated values. Throughput tests resulted satisfactory. The thesis provides detailed systematic procedures for Wi-Fi radio link setup and techniques to optimize the quality of a radio link.
Contributing Partner: UNT Libraries
Study of the effects of background and motion camera on the efficacy of Kalman and particle filter algorithms.

Study of the effects of background and motion camera on the efficacy of Kalman and particle filter algorithms.

Date: August 2009
Creator: Morita, Yasuhiro
Description: This study compares independent use of two known algorithms (Kalmar filter with background subtraction and Particle Filter) that are commonly deployed in object tracking applications. Object tracking in general is very challenging; it presents numerous problems that need to be addressed by the application in order to facilitate its successful deployment. Such problems range from abrupt object motion, during tracking, to a change in appearance of the scene and the object, as well as object to scene occlusions, and camera motion among others. It is important to take into consideration some issues, such as, accounting for noise associated with the image in question, ability to predict to an acceptable statistical accuracy, the position of the object at a particular time given its current position. This study tackles some of the issues raised above prior to addressing how the use of either of the aforementioned algorithm, minimize or in some cases eliminate the negative effects
Contributing Partner: UNT Libraries
A New Wireless Sensor Node Design for Program Isolation and Power Flexibility

A New Wireless Sensor Node Design for Program Isolation and Power Flexibility

Date: December 2009
Creator: Skelton, Adam W.
Description: Over-the-air programming systems for wireless sensor networks have drawbacks that stem from fundamental limitations in the hardware used in current sensor nodes. Also, advances in technology make it feasible to use capacitors as the sole energy storage mechanism for sensor nodes using energy harvesting, but most current designs require additional electronics. These two considerations led to the design of a new sensor node. A microcontroller was chosen that meets the Popek and Goldberg virtualization requirements. The hardware design for this new sensor node is presented, as well as a preliminary operating system. The prototypes are tested, and demonstrated to be sustainable with a capacitor and solar panel. The issue of capacitor leakage is considered and measured.
Contributing Partner: UNT Libraries
A Study of Anti-collision Multi-tag Identification Algorithms for Passive RFID Systems

A Study of Anti-collision Multi-tag Identification Algorithms for Passive RFID Systems

Date: May 2010
Creator: Kamineni, Neelima
Description: The major advantages of radio frequency identification (RFID) technology over barcodes are that the RFID-tagged objects do not require to be in line-of-sight with the reader for their identification and multiple objects can be read simultaneously. But when multiple objects are read simultaneously there is always a problem of collision which reduces the efficiency of the system. This thesis presents a comprehensive study of the dynamic framed slotted ALOHA (DFSA)-based anti-collision multi-tag identification algorithms for passive RFID system. Performance of various DFSA algorithms is compared through extensive simulation results. In addition, a number of simple performance improvement techniques have also been investigated in this thesis, including improved estimation techniques for the number of tags in each read cycle and a low-complexity heuristic stopping criterion that can be easily implemented in the practical system.
Contributing Partner: UNT Libraries
Design and Implementation of Communication Platform for Autonomous Decentralized Systems

Design and Implementation of Communication Platform for Autonomous Decentralized Systems

Date: December 2010
Creator: Gottipati, Naga Sravani
Description: This thesis deals with the decentralized autonomous system, in which individual nodes acting like peers, communicate and participate in collaborative tasks and decision making processes. An experimental test-bed is created using four Garcia robots. The robots act like peers and interact with each other using user datagram protocol (UDP) messages. Each robot continuously monitors for messages coming from other robots and respond accordingly. Each robot broadcasts its location to all the other robots within its vicinity. Robots do not have built-in global positioning system (GPS). So, an indoor localization method based on signal strength is developed to estimate robot's position. The signal strength that the robot gets from the nearby wireless access points is used to calculate the robot's position. Trilateration and fingerprint are some of the indoor localization methods used for this purpose. The communication functionality of the decentralized system has been tested and verified in the autonomous systems laboratory.
Contributing Partner: UNT Libraries
Implementation of Turbo Codes on GNU Radio

Implementation of Turbo Codes on GNU Radio

Date: December 2010
Creator: Talasila, Mahendra
Description: This thesis investigates the design and implementation of turbo codes over the GNU radio. The turbo codes is a class of iterative channel codes which demonstrates strong capability for error correction. A software defined radio (SDR) is a communication system which can implement different modulation schemes and tune to any frequency band by means of software that can control the programmable hardware. SDR utilizes the general purpose computer to perform certain signal processing techniques. We implement a turbo coding system using the Universal Software Radio Peripheral (USRP), a widely used SDR platform from Ettus. Detail configuration and performance comparison are also provided in this research.
Contributing Partner: UNT Libraries
Consensus Building in Sensor Networks and Long Term Planning for the National Airspace System

Consensus Building in Sensor Networks and Long Term Planning for the National Airspace System

Date: May 2011
Creator: Akula, Naga Venkata Swathik
Description: In this thesis, I present my study on the impact of multi-group network structure on the performance of consensus building strategies, and the preliminary mathematical formulation of the problem on improving the performance of the National Airspace system (NAS) through long-term investment. The first part of the thesis is concerned with a structural approach to the consensus building problem in multi-group distributed sensor networks (DSNs) that can be represented by bipartite graph. Direct inference of the convergence behavior of consensus strategies from multi-group DSN structure is one of the contributions of this thesis. The insights gained from the analysis facilitate the design and development of DSNs that meet specific performance criteria. The other part of the thesis is concerned with long-term planning and development of the NAS at a network level, by formulating the planning problem as a resource allocation problem for a flow network. The network-level model viewpoint on NAS planning and development will give insight to the structure of future NAS and will allow evaluation of various paradigms for the planning problem.
Contributing Partner: UNT Libraries
Simulation and Performance Analysis of Strategic Air Traffic Management under Weather Uncertainty

Simulation and Performance Analysis of Strategic Air Traffic Management under Weather Uncertainty

Date: May 2011
Creator: Zhou, Yi
Description: In this thesis, I introduce a promising framework for representing an air traffic flow (stream) and flow-management action operating under weather uncertainty. I propose to use a meshed queuing and Markov-chain model---specifically, a queuing model whose service-rates are modulated by an underlying Markov chain describing weather-impact evolution---to capture traffic management in an uncertain environment. Two techniques for characterizing flow-management performance using the model are developed, namely 1) a master-Markov-chain representation technique that yields accurate results but at relatively high computational cost, and 2) a jump-linear system-based approximation that has promising scalability. The model formulation and two analysis techniques are illustrated with numerous examples. Based on this initial study, I believe that the interfaced weather-impact and traffic-flow model analyzed here holds promise to inform strategic flow contingency management in NextGen.
Contributing Partner: UNT Libraries
FIRST PREV 1 2 3 4 NEXT LAST