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Articles 1 - 11 of 11
Full-Text Articles in Engineering
Modulation And Multiple Access Techniques For Ultra-Wideband Communication Systems, Song Cui
Modulation And Multiple Access Techniques For Ultra-Wideband Communication Systems, Song Cui
ETD Archive
Two new energy detection (ED) Ultra-Wideband (UWB) systems are proposed in this dissertation. The first one is an ED UWB system based on pulse width modulation (PWM). The bit error rate (BER) performance of this ED PWM system is slightly worse than ED pulse position modulation (PPM) system in additive white Gaussian noise (AWGN) channels. However, the BER performance of this ED PWM system surpasses that of a PPM system in multipath channels since a PWM system does not suffer cross-modulation interference (CMI) as a PPM system. In the presence of synchronization errors, the BER performance of a PWM system …
Simplifying Embedded System Development Through Whole-Program Compilers, William Patrick Mccartney
Simplifying Embedded System Development Through Whole-Program Compilers, William Patrick Mccartney
ETD Archive
As embedded systems embrace ever more complicated microcontrollers, they present both new capability and new complexity. To simplify their development, some lessons of computer application development will translate with additional work. This thesis offers one such translation. It shows how whole-program compilers - those that broadly analyze a program's entire source code - can achieve performance gains and remove faults in embedded system applications. In so doing, this yields a novel stackless threading system named UnStacked C. UnStacked C enables cooperative multithreading without the risk of stack overflows in embedded system applications. We also propose a novel preemption system called …
Wireless Signals And Male Fertility, Rand Mouradi
Wireless Signals And Male Fertility, Rand Mouradi
ETD Archive
Rapid advances in wireless technology have increased the number of users of mobile devices. As of 2011, the number of cell phone subscribers have reached 5.3 billion worldwide. Mobile devices have saturated our environment with radio frequency (RF) signals. This situation has created public concern over the effect of such signals on human health. This dissertation focuses on the correlation of RF signals emitted by cell phones with male infertility. A thorough discussion is provided on the effects of RF signals on the development of central nervous system (CNS) neoplasm, the design of these mobile devices, the range of the …
Partial-Data Interpolation During Arcing Of An X-Ray Tube In A Computed Tomography Scanner, Jaisingh Rajwade
Partial-Data Interpolation During Arcing Of An X-Ray Tube In A Computed Tomography Scanner, Jaisingh Rajwade
ETD Archive
X-ray tubes are used in computed tomography (CT) scanners as the energy source for generation of images. These tubes occasionally tend to arc, an undesired phenomenon where high current surges through the tube. During the time that the x-ray tube recovers to full voltage after an arc, image data is being collected. Normally this data, acquired at less than full voltage, is discarded and interpolation is performed over the arc duration. However, this is not ideal and some residual imperfections in images, called artifacts, still remain. Proposed here is an algorithm that corrects for improper tube voltage, allowing previously discarded …
Free Space Optical Communications With High Intensity Laser Power Beaming, Daniel Edward Raible
Free Space Optical Communications With High Intensity Laser Power Beaming, Daniel Edward Raible
ETD Archive
This research demonstrates the feasibility of utilizing high intensity laser power beaming (HILPB) systems as a conduit for robust free-space optical communications over large distances and in challenging atmospheric conditions. The uniqueness of vertical multi-junction (VMJ) photovoltaic cells used in HILPB systems in their ability to receive and to convert at high efficiency, very high intensity laser light of over 200 W/cm2, presents a unique opportunity for the development of the robust free space optical communication system by modulating information signals onto the transmitted high intensity photonic energy. Experiments were conducted to investigate and validate several optical communications concepts. A …
Dynamic Harmonic Domain Modeling Of Flexible Alternating Current Transmission System Controllers, Bharat Gnvsr Vyakaranam
Dynamic Harmonic Domain Modeling Of Flexible Alternating Current Transmission System Controllers, Bharat Gnvsr Vyakaranam
ETD Archive
Flexible alternating current transmission system (FACTS) and multi-line FACTS controllers play an important role in electrical power transmission systems by improving power quality and increasing power transmission capacity. These controllers are nonlinear and highly complex when compared to mechanical switches. Consequently, during transient conditions, it is very difficult to use conventional time and frequency domain techniques alone to determine the precise dynamic behavior of the harmonics introduced into the system by these controllers. In particular, the time-varying nature of the harmonic components is not captured by these techniques. The contribution of this work to the state of power systems analysis …
Intelligent Controls For A Semi-Active Hydraulic Prosthetic Knee, Timothy Allen Wilmot
Intelligent Controls For A Semi-Active Hydraulic Prosthetic Knee, Timothy Allen Wilmot
ETD Archive
We discuss open loop control development and simulation results for a semi-active above-knee prosthesis. The control signal consists of two hydraulic valve settings. These valves control a rotary actuator that provides torque to the prosthetic knee. We develop open loop control using biogeography-based optimization (BBO), which is a recently developed evolutionary algorithm, and gradient descent. We use gradient descent to show that the control generated by BBO is locally optimal. This research contributes to the field of evolutionary algorithms by demonstrating that BBO is successful at finding optimal solutions to complex, real-world, nonlinear, time varying control problems. The research contributes …
The Relational Database: A New Static Analysis Tool?, Adam M. Dutko
The Relational Database: A New Static Analysis Tool?, Adam M. Dutko
ETD Archive
Code comprehension is pivotal to reducing errors in software. Reading source code improves code comprehension and enables effective fixes but as a code base grows meta-data become increasingly important. Static Analysis techniques provide an avenue for software developers to learn more about their code through meta-data while also helping them safely detect potential errors in their source. Unfortunately, many Static Analysis tools have a steep learning curve and are limited in scope. This thesis seeks to make Static Analysis accessible and extensible by asking what ubiquitous tools like SQL and relational databases can offer and what they cannot. We begin …
Efficient Time Of Arrival Calculation For Acoustic Source Localization Using Wireless Sensor Networks, Prashanth G. Reddy
Efficient Time Of Arrival Calculation For Acoustic Source Localization Using Wireless Sensor Networks, Prashanth G. Reddy
ETD Archive
Acoustic source localization is a very useful tool in surveillance and tracking applications. Potential exists for ubiquitous presence of acoustic source localization systems. However, due to several significant challenges they are currently limited in their applications. Wireless Sensor Networks (WSN) offer a feasible solution that can allow for large, ever present acoustic localization systems. Some fundamental challenges remain. This thesis presents some ideas for helping solve the challenging problems faced by networked acoustic localization systems. We make use of a low-power WSN designed specifically for distributed acoustic source localization. Our ideas are based on three important observations. First, sounds emanating …
Implementing A Piezoelectric Transformer For A Ferroelectric Phase Shifter Circuit, Anthony M. Roberts
Implementing A Piezoelectric Transformer For A Ferroelectric Phase Shifter Circuit, Anthony M. Roberts
ETD Archive
No abstract provided.
Implementation Of An Advanced Controller On A Torsional Mechanism, Chintan Trivedi
Implementation Of An Advanced Controller On A Torsional Mechanism, Chintan Trivedi
ETD Archive
The hardware implementation of an active disturbance rejection controller (ADRC) is presented in the thesis for a mechanical torsional plant. ADRC is a novel disturbance rejection control technique that is not completely dependent on mathematical models of physical systems. In ADRC framework external disturbances, system uncertainties, and internal dynamics of the system are estimated as a generalized disturbance by an extended state observer and the generalized disturbance is effectively canceled by a PD controller. A torsional plant represents a class of rotational systems. Its control challenges are the vibrations caused by mass imbalance, centrifugal imbalance, and the imbalance caused by …