Engineering Commons^™

Plasmonic Field Confinement For Separate Absorption-Multiplication In Ingaas Nanopillar Avalanche Photodiodes, Alan C. Farrell, Pradeep Senanayake, Chung-Hong Hung, George El-Howayek, Abhejit Rajagopal, Marc Currie, Majeed M. Hayat, Diana L. Huffaker

Electrical and Computer Engineering Faculty Research and Publications

Avalanche photodiodes (APDs) are essential components in quantum key distribution systems and active imaging systems requiring both ultrafast response time to measure photon time of flight and high gain to detect low photon flux. The internal gain of an APD can improve system signal-to-noise ratio (SNR). Excess noise is typically kept low through the selection of material with intrinsically low excess noise, using separate-absorption-multiplication (SAM) heterostructures, or taking advantage of the dead-space effect using thin multiplication regions. In this work we demonstrate the first measurement of excess noise and gain-bandwidth product in III–V nanopillars exhibiting substantially lower excess noise factors …

Forecasting Design Day Demand Using Extremal Quantile Regression, David Joseph Kaftan, Jarrett L. Smalley, George F. Corliss, Ronald H. Brown, Richard James Povinelli

Electrical and Computer Engineering Faculty Research and Publications

Extreme events occur rarely, making them difficult to predict. Extreme cold events strain natural gas systems to their limits. Natural gas distribution companies need to be prepared to satisfy demand on any given day that is at or warmer than an extreme cold threshold. The hypothetical day with temperature at this threshold is called the Design Day. To guarantee Design Day demand is satisfied, distribution companies need to determine the demand that is unlikely to be exceeded on the Design Day.

We approach determining this demand as an extremal quantile regression problem. We review current methods for extremal quantile regression. …

Fast Gpu-Based Approach To Branchless Distance-Driven Projection And Back-Projection In Cone Beam Ct, Daniel Edward Schlifske

Master's Theses (2009 -)

Modern CT image reconstruction algorithms rely on projection and back-projection operations to refine an image estimate in iterative image reconstruction. A widely-used state-of-the-art technique is distance-driven projection and back-projection. While the distance-driven technique yields superior image quality in iterative algorithms, it is a computationally demanding process. This has a detrimental effect on the relevance of the algorithms in clinical settings. A few methods have been proposed for enhancing the distance-driven technique in order to take advantage of modern computer hardware. This study explores a two-dimensional extension of the branchless method, which is a technique that does not compromise image quality. …

Towards Mhealth Solutions For Asthma Patients, Nahid Negar

Master's Theses (2009 -)

With the recent, rapid growth in mobile-computing technology, mobile health (mHealth) is becoming a popular research topic. mHealth is one of several examples of how using technology in the health sector is being more advanced every day. mHealth is being applied to the care of a broad spectrum of diseases from acute to chronic, such as the flu, asthma, and cancer. Due to the easy-to-understand and friendly user interfaces, mobility and cost effectiveness; a mobile application can be a powerful tool to collect patient information. Asthma is a common disease around the globe. Collecting the proper symptom, trigger, peak-flow and …

Bidirectional Ac-Dc Converter For Vehicle-To-Grid (V2g) Applications, Arjun Raj Prabu Andhra Sridhar

Master's Theses (2009 -)

Electric vehicles are growing at a rapid pace in the internal combustion engine dominated transportation sector, and bring environmental and economic benefits to society. Electric vehicles produce nearly zero carbon emission, provided that they are charged through renewable energy sources. Electric vehicles reduce our dependency on foreign oil and also offer additional benefits like Vehicle-to-grid (V2G). V2G is a technology that allows electric energy stored in the electric vehicle batteries to be returned to the grid during peak demand. V2G can also provide voltage regulation, voltage shaving, reactive power compensation and distributed generation. This necessitates that an electric vehicle battery …

Error Probabilities For Optical Receivers That Employ Dynamically Biased Avalanche Photodiodes, Georges El-Howayek, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

A novel theory was recently reported for the avalanche multiplication process in avalanche photodiodes (APDs) under dynamic reverse-biasing conditions. It has been shown theoretically that the bit-synchronized, periodic modulation of the electric field in the multiplication region can offer improvements in the gain-bandwidth product by reducing intersymbol interference in optical receivers. This paper reports a rigorous formulation of the sensitivity of optical receivers that employ dynamically biased APDs. To enable the sensitivity analysis, a recurrence theory is developed to calculate the joint probability distribution function (PDF) of the stochastic gain and avalanche buildup time in APDs that are operated under …

Survivable Cloud Network Mapping For Disaster Recovery Support, Feng Gu, Khaled B. Shaban, Nasir Ghani, Samee Khan, Mahshid R. Naeini, Majeed M. Hayat, Chadi Assi

Electrical and Computer Engineering Faculty Research and Publications

Network virtualization is a key provision for improving the scalability and reliability of cloud computing services. In recent years, various mapping schemes have been developed to reserve VN resources over substrate networks. However, many cloud providers are very concerned about improving service reliability under catastrophic disaster conditions yielding multiple system failures. To address this challenge, this work presents a novel failure region-disjoint VN mapping scheme to improve VN mapping survivability. The problem is first formulated as a mixed integer linear programming problem and then two heuristic solutions are proposed to compute a pair of failure region-disjoint VN mappings. The solution …

Improved Terahertz Modulation Using Germanium Telluride (Gete) Chalcogenide Thin Films, A. H. Gwin, C. H. Kodama, T. Laurvick, Ronald A. Coutu Jr., P. F. Taday

Electrical and Computer Engineering Faculty Research and Publications

We demonstrate improved terahertz (THz) modulation using thermally crystallized germanium telluride (GeTe) thin films. GeTe is a chalcogenidematerial that exhibits a nonvolatile, amorphous to crystalline phase change at approximately 200 °C, as well as six orders of magnitude decreased electrical resistivity. In this study, amorphous GeTe thin filmswere sputtered on sapphire substrates and then tested using THz time-domain spectroscopy (THz-TDS). The test samples, heated in-situ while collecting THz-TDS measurements, exhibited a gradual absorbance increase, an abrupt nonvolatile reduction at the transition temperature, followed by another gradual increase in absorbance. The transition temperature was verified by conducting similar thermal tests while …

Establishing The Relative Merits Of Interior And Spoke-Type Permanent-Magnet Machines With Ferrite Or Ndfeb Through Systematic Design Optimization, Peng Zhang, Gennadi Y. Sizov, Dan M. Ionel, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

In this paper, a multiobjective design optimization method combining design-of-experiments techniques and differential-evolution algorithms is presented. The method was implemented and utilized in order to provide practical engineering insights for the optimal design of interior and spoke-type permanent-magnet machines. Two combinations with 12 slots and 8 poles and 12 slots and 10 poles, respectively, have been studied in conjunction with rare-earth neodymium-iron-boron (NdFeB) and ferrites. As part of the optimization process, a computationally efficient finite-element electromagnetic analysis was employed for estimating the performance of thousands of candidate designs. Three optimization objectives were concurrently considered for minimum total material cost, power …

Design And Characterization Of A Low Cost Mems Imu Cluster For Precision Navigation, Daniel R. Greenheck

Master's Theses (2009 -)

The fast paced development of micro-electromechanical systems (MEMS) technology in recent years has resulted in the availability of low cost gyroscopes and accelerometers in commercial markets. These sensors can be integrated into a single device known as an inertial measurement unit (IMU). An IMU is capable of tracking and navigating a vehicle for a short period of time in the absence of external position and attitude updates. The precision of the manufacturing techniques used to fabricate commercial MEMS sensors as well as their mechanical nature result in noise and errors that limit their performance. It has been mathematically shown that …

Vocal Classification Of Vocalizations Of A Pair Of Asian Small-Clawed Otters To Determine Stress, Peter M. Scheifele, Michael T. Johnson, Michelle Fry, Benjamin Hamel, Kathryn Laclede

Electrical and Computer Engineering Faculty Research and Publications

Asian Small-Clawed Otters (Aonyx cinerea) are a small, protected but threatened species living in freshwater. They are gregarious and live in monogamous pairs for their lifetimes, communicating via scent and acoustic vocalizations. This study utilized a hidden Markov model (HMM) to classify stress versus non-stress calls from a sibling pair under professional care. Vocalizations were expertly annotated by keepers into seven contextual categories. Four of these—aggression, separation anxiety, pain, and prefeeding—were identified as stressful contexts, and three of them—feeding, training, and play—were identified as non-stressful contexts. The vocalizations were segmented, manually categorized into broad vocal type call types, and analyzed …

Common Mode Voltage Mitigation Strategies Using Pwm In Neutral-Point-Clamped Multilevel Inverters, Chad Alexander Somogyi

Master's Theses (2009 -)

Over the last several decades, there has been consistent growth in the research and development of multilevel voltage-source inverter-based adjustable speed motor drives (ASDs) as a result of low cost, high reliability power semiconductors. The three-level neutral-point-clamped (NPC) ASD is a popular multilevel inverter used in low and medium voltage applications because of its ability to produce lower levels of total harmonic distortion (THD) and withstand higher voltages while preserving the rated output power compared to two-level ASDs. As with other voltage-source inverters, three-level NPC ASDs produce common-mode voltage (CMV) that can cause motor shaft voltages, bearing currents, and excess …

Investigation Of The Surface Adhesion Phenomena And Mechanism Of Gold-Plated Contacts At Superlow Making/Breaking Speed, Wanbin Ren, Cheng Chang, Yu Chen, Shengjun Xue, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

Surface adhesion phenomena of gold-plated copper contact materials are studied in conditions of nonarc load (5/15/25 V and 0.2/0.5/1 A) and superlow speed (25 and 50 nm/s) realized by a piezoactuator during the making and breaking processes. It is shown that softening and melting of local asperities leads to interface adhesion, which results from the joule heat generated by the contact resistance; it is determined that the change of contact force with time obeys the negative exponential distribution and the time constant is associated with the adhesion force directly. Based on the fitting experimental data, the relationship between the adhesion …

Relating The Experimental Ionization Coefficients In Semiconductors To The Nonlocal Ionization Coefficients, Jeng Shiuh Cheong, Majeed M. Hayat, Xinxin Zhou, John P.R. David

Electrical and Computer Engineering Faculty Research and Publications

The experimentally determined impact ionization coefficients, , include intrinsically the presence of a dead-space, where carriers cannot impact ionize as they do not have sufficient energy. These, therefore, cannot be used by nonlocal ionization models, which require the enabled ionization coefficients, which describe the ionization probability after the dead-space. A relatively simple relationship is shown to exist between α'(β') and , which requires only the knowledge of the carrier threshold energies. This allows conventionally limited to the local model framework, to be used to give a very good prediction of the avalanche multiplication and excess noise for a wide range …

Data Cleaning In The Energy Domain, Hermine Nathalie Akouemo Kengmo Kenfack

Dissertations (1934 -)

This dissertation addresses the problem of data cleaning in the energy domain, especially for natural gas and electric time series. The detection and imputation of anomalies improves the performance of forecasting models necessary to lower purchasing and storage costs for utilities and plan for peak energy loads or distribution shortages. There are various types of anomalies, each induced by diverse causes and sources depending on the field of study. The definition of false positives also depends on the context. The analysis is focused on energy data because of the availability of data and information to make a theoretical and practical …

Using Cross-Linked Su-8 To Flip-Chip Bond, Assemble, And Package Mems Devices, Robert A. Lake, Ronald A. Coutu Jr.

Electrical and Computer Engineering Faculty Research and Publications

This paper investigates using an SU-8 photoresist as an adhesive material for flip-chip bonding, assembling, and packaging microelectromechanical systems devices. An important factor, when using SU-8 as an adhesive material is to control ultraviolet (UV) exposure during fabrication to maximize bond strength due to material cross linking. This approach is much improved over previous efforts where SU-8 bake times and temperatures where changed to alter material cross-linking. In this paper, bake times and temperatures were maintained constant and total UV exposure energy was varied. Once fabricated, bond strength was systematically tested to determine the tensile loads needed to separate bonded …

Analytical Modeling Of A Novel High-Q Disk Resonator For Liquid-Phase Applications, Mohomad S. Sotoudegan, Stephen M. Heinrich, Fabien Josse, Nicholas J. Nigro, Isabelle Dufour, Oliver Brand

Civil and Environmental Engineering Faculty Research and Publications

To overcome the detrimental effects of liquid environments on microelectromechanical systems resonator performance, the in-fluid vibration of a novel disk resonator supported by two electrothermally driven legs is investigated through analytical modeling and the effects of the system’s geometric/material parameters on the dynamic response are explored. The all-shear interaction device (ASID) is based on engaging the surrounding fluid primarily through shearing action. The theory comprises a continuous-system, multimodal model, and a single-degree-of-freedom model, the latter yielding simple formulas for the fundamental-mode resonant characteristics that often furnish excellent estimates to the results based on the more general model. Comparisons between theoretical …

Breaking The Buildup-Time Limit Of Sensitivity In Avalanche Photodiodes By Dynamic Biasing, Majeed M. Hayat, Payman Zarkesh-Ha, George El-Howayek, Robert Efroymson, Joe C. Campbell

Electrical and Computer Engineering Faculty Research and Publications

Avalanche photodiodes (APDs) are the preferred photodetectors for direct-detection, high data-rate long-haul optical telecommunications. APDs can detect low-level optical signals due to their internal amplification of the photon-generated electrical current, which is attributable to the avalanche of electron and hole impact ionizations. Despite recent advances in APDs aimed at reducing the average avalanche-buildup time, which causes intersymbol interference and compromises receiver sensitivity at high data rates, operable speeds of commercially available APDs have been limited to 10Gbps. We report the first demonstration of a dynamically biased APD that breaks the traditional sensitivity-versus-speed limit by employing a data-synchronous sinusoidal reverse-bias that …

Predicting Scenarios For Successful Autodissemination Of Pyriproxyfen By Malaria Vectors From Their Resting Sites To Aquatic Habitats; Description And Simulation Analysis Of A Field-Parameterizable Model, Samson Sifael Kiware, George F. Corliss, Stephen Merrill, Dickson W. Lwetoijera, Gregor J. Devine, Silas Majambere, Gerry F. Killeen

Electrical and Computer Engineering Faculty Research and Publications

Background

Large-cage experiments indicate pyriproxifen (PPF) can be transferred from resting sites to aquatic habitats by Anopheles arabiensis - malaria vector mosquitoes to inhibit emergence of their own offspring. PPF coverage is amplified twice: (1) partial coverage of resting sites with PPF contamination results in far higher contamination coverage of adult mosquitoes because they are mobile and use numerous resting sites per gonotrophic cycle, and (2) even greater contamination coverage of aquatic habitats results from accumulation of PPF from multiple oviposition events.

Methods and Findings

Deterministic mathematical models are described that use only field-measurable input parameters and capture the biological …