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Full-Text Articles in Engineering

Study Of Electronic Characteristics Of Heterojunction With Intrinsic Thin-Layer Devices And Defect Density Profile Of Nanocrystalline Silicon Germanium Devices, Watson Paul Mulder Jan 2015

Study Of Electronic Characteristics Of Heterojunction With Intrinsic Thin-Layer Devices And Defect Density Profile Of Nanocrystalline Silicon Germanium Devices, Watson Paul Mulder

Graduate Theses and Dissertations

Heterojunction with Intrinsic Thin-layer (HIT) solar cells are an important photovoltaic technology, recently reaching record power conversion efficiencies. HIT cells hold advantages over the conventional crystalline Si solar cells, such as their fabrication at lower temperatures and their shorter fabrication time. It is important to understand the electronic characteristics and transport properties of HIT cells to continue to improve their efficiencies. The fundamental measurements of a HIT solar cell with an innovative n+/p/p+ structure are presented. We also report on a series of these HIT cells fabricated on wafers with different doping concentrations, observing the relationship between doping ...


Uncertainty In Power System Planning, Oluwaseyi Ayorinde Olatujoye Jan 2015

Uncertainty In Power System Planning, Oluwaseyi Ayorinde Olatujoye

Graduate Theses and Dissertations

Deterministic transmission planning is based on deterministic assumptions, by planning for a single forecasted set of conditions. The issue of adaptability in transmission and generation expansion planning has become important for planners in order to deal with future uncertainties. Adaptability is "the ability to change (or be changed) to fit changed circumstances" [ ]. Adaptability planning helps mitigate losses in unforeseen situations and exploit opportunities in expected situations. Adaptability also provides the opportunities to take alternative actions after events unfold. Adaptable plans can help reduce future costs and time, and it also reduces complexity associated with possible future changes to the existing ...


A Broadband Bistable Piezoelectric Cantilever-Based Vibration Energy Harvester With Nonlinear High Power Extraction, Kanishka Aman Singh Jan 2015

A Broadband Bistable Piezoelectric Cantilever-Based Vibration Energy Harvester With Nonlinear High Power Extraction, Kanishka Aman Singh

Graduate Theses and Dissertations

This work presents a nonlinear vibration energy harvester, which combines a nonlinear bistable broadband piezoelectric cantilever used to transduce ambient vibration energy, with synchronized capture for efficient harvesting over broadband sources. An accurate model of the bistable transducer, that augments the Butterworth van Dyke piezoelectric model to capture the external magnetic force added as a bias to the external vibrations, is presented. Its validity has been demonstrated through physical implementation and experimental validation against simulation of the mathematical model. For efficient extraction of the transduced energy, nonlinear extraction circuits, namely synchronous charge extraction (SCE) and parallel synchronized switch harvesting on ...


Dynamic Optimization Based Reactive Power Planning For Improving Short-Term Voltage Performance, Magesh Kumar Paramasivam Jan 2015

Dynamic Optimization Based Reactive Power Planning For Improving Short-Term Voltage Performance, Magesh Kumar Paramasivam

Graduate Theses and Dissertations

Short term voltage stability in the form of delayed voltage recovery (FIDVR) poses a significant threat to system stability and reliability. This work examines the voltage instability issue in a power system with dense concentration of induction motor loads and applies dynamic VAR injection as a counter-measure to ensure short term voltage stability following a large disturbance. The dynamic behavior of motor loads, such as decelerating and stalling, is considered as the major cause of FIDVR incidents especially during summer peak load conditions in areas where low inertia single-phase air conditioning (A/C) motors comprise a significant portion of the ...


Energy Efficiency In Cognitive Radio Network: Study Of Cooperative Sensing Using Different Channel Sensing Methods, Chenxuan Cui Jan 2015

Energy Efficiency In Cognitive Radio Network: Study Of Cooperative Sensing Using Different Channel Sensing Methods, Chenxuan Cui

Graduate Theses and Dissertations

When cognitive radio (CR) operates, it starts by sensing spectrum and looking for idle bandwidth. There are several methods for CR to make a decision on either the channel is occupied or idle, for example, energy detection scheme, cyclostationary detection scheme and matching filtering detection scheme [1]. Among them, the most common method is energy detection scheme because of its algorithm and implementation simplicities [2]. There are two major methods for sensing, the first one is to sense single channel slot with varying bandwidth, whereas the second one is to sense multiple channels and each with same bandwidth. After sensing ...