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电子学 & 通信 : 学术学位
This dissertation investigates major operating and pricing issues associated with unbundled transmission systems, including transmission loss allocation, parallel flow evaluation, transmission pricing, coordination of different energy trading markets, congestion management and transmission rights, d
In view of limited spectral resources, the explosive growth in the number of wireless users accompanied by a shift to more sophisticated broadband services, makes mutual interference among users an increasingly pressing problem. Despite the fact that antenna arrays and beamforming are widely recogni
The goal of this research was to build an Nx N all-optical WDM switch, which is indispensable for the next-generation of all-optical packet-switched networks. We started from the basic concepts of telecommunication network architectures, optical networks, WDM network elements and basic components in
A methodology for evaluating and reducing rotor losses, heating, and operational limitations of high-speed flywheel batteries.
Flywheel batteries are machines that store kinetic energy in the form of a rotating flywheel. Energy is transferred to and from the flywheel via a motor-generator mounted on the flywheel rotor. For mobile systems in particular, it is important to maximize the stored energy while minimizing the mass
Three main types of electric machines, DC motors, AC induction motors, and AC synchronous motors, have driven industry for nearly a century. Although brushed machines are more expensive in terms of maintenance and manufacture when compared to their brushless counterparts, they have been historically
Eigenvalue decomposition and multiresolution are widely used techniques for signal representation. Both techniques divide a signal into an ordered set of components. The first component can be considered an approximation of the input signal; subsequent components improve the approximation. Principal
Effect of current crowding and device structure on operation of gallium nitride-based light-emitting diodes.
The photon recycling semiconductor (PRS) light emitting diode (LED) is a concept to produce both colorful and white LEDs. PRS LEDs have two or more active regions in one chip. Only the active region that emits in the shortest wavelength, which is called the primary active region, is injected with cu
Astronomic and atmospheric remote sensing in the THz region have driven the demand for highly-sensitive mixers/receivers and focal-plane imaging arrays. Niobium hot-electron bolometers (HEB's) have received much attention in recent years owning to their merits such as broad IF bandwidth, high sensit
The Iterative Closest Point (ICP) algorithm is one of the most commonly used range image processing methods. However, slow operational speeds and high input bandwidths limit the use of ICP in high-speed real-time applications.;This thesis presents and examines a novel hardware implementation of a hi
Over the years, Frequency Selective Surfaces (FSSs) have found frequent use as radomes and spatial filters in both commercial and military applications. Past research has concentrated on the synthesis of broadband microwave absorbers and spatial filters using multilayered dielectrics via the applica
Cardiac arrhythmia is the number one cause of cardiac arrest and is currently treated with a number of different ablation techniques, drugs, or implantable defibrillators. A direct and lasting cure can be obtained by ablating certain tissue regions using catheters. However, catheter based ablation i
A fast method for computing current distribution on printed circuit boards and microwave integrated circuits using the method of moments.
In order to determine current distribution on Printed Circuit Board (PCB) or Microwave Integrated Circuit (MIC) structure using the full-wave Method of Moments (MoM), the impedance of the structure must be computed first. A full-wave impedance matrix is frequency dependent in a non-trivial way; Gree
Conventional in-plane lasers are poorly suited to direct intensity modulation, due to their limited differential efficiency and inherently low input impedance. Bipolar cascade lasers address these problems by incorporating multiple diodes, connected in series, but have proven very difficult to make,
Embedded personal authentication systems based on biometric information offers great security and convenience. The biometric processing is data intensive and the implementation on a resource-constrained mobile device is required to be efficient in terms of speed, memory, as well as energy consumptio
This dissertation considers four independent but interconnected problems relating to motion estimation and motion-based segmentation in digital image sequences. The work is based on velocity tuned 2D + T filter method which tunes the mother function to spatial translation, temporal translation, spat
A study of power electronic building block (PEBB)-based integrated shipboard power systems during reconfiguration.
The U.S. Navy has developed in their ships, and is continually improving, electric propulsion, ship service power, and electric loads. The latest topology under design is the integrated power system (IPS). The IPS entails the all electric ship concept with electric propulsion, direct current (DC) di
Wireless communications system performance under fading conditions can be greatly improved when multiple antennas are used at the transmitter and/or at the receiver. Information-theoretic results indicate that, under certain fading statistics, the available data rates are proportional to the antenna
Growth and characterization of nanocrystalline diamond films for microelectronics and microelectromechanical systems.
Diamond is widely known for its extraordinary properties, such as high thermal conductivity, energy bandgap and high material hardness and durability making it a very attractive material for microelectronic and mechanical applications. Synthetic diamonds produced by chemical vapor deposition (CVD) m
DESIGN AND FABRICATION OF MONOLITHIC BROADBAND MICROWAVE GALLIUM-ARSENIDE LOW NOISE FET AMPLIFIERS (MMIC, CAD, CHARACTERIZATION).
The design of a broadband low noise FET amplifier is a complicated process since it requires achieving both flat gain and a low noise figure over the desired octave frequency band. Difficulties also occur in the realization of these designs due to limitations in fabrication techniques. This thesis r
The scaling of CMOS technology has made it feasible to integrate complex digital signal processing functions in wireless transceivers. Several analog functions in communication systems are increasingly being displaced by algorithms implemented in a digital baseband processor. As a result, more strin