Engineering Commons^™

An Optogenetic Brain-Machine Interface For Spatiotemporal Neuromodulation, Ryan Andrew Baumgartner

Theses and Dissertations

Direct neural stimulation has recently become a standard therapy for neurological disorders such as Parkinson's Disease, Essential Tremors, and Dystonia. Currently, deep brain electro-stimulation and neuro-pharmaceutical treatments are the dominant therapeutic options available to the public. As our understanding of brain function and neurological diseases improves, we are able to develop more advanced neuromodulation techniques. These methods could become viable treatment solutions for treating brain dysfunction. Optogenetics, first introduced by a research team led by Karl Deisseroth at Stanford University, has proved to be a versatile technique with remarkable potential to be used in treatments for brain disorders, dysfunction, and …

Improving Mri Surface Coil Decoupling To Reduce B1 Distortion, Christian K. Larson

Theses and Dissertations

As clinical MRI systems continue to advance, larger focus is being given to image

uniformity. Good image uniformity begins with generating uniform magnetic fields, which

are easily distorted by induced currents on receive-only surface coils. It has become an

industry standard to combat these induced currents by placing RF blocking networks on

surface coils. This paper explores the effect of blocking network impedance of phased array surface coils on B1 distortion. It has been found and verified, that traditional approaches for blocking network design in complex phased arrays can leave undesirable B1 distortions at 3 Tesla. The traditional approach of …

A Novel Transport Based Model For Wire Media And Its Application To Scattering Problems, Ebrahim Forati

Theses and Dissertations

Artificially engineered materials, known as metamaterials, have attracted the interest of researchers because of the potential for novel applications. Effective modeling of metamaterials is a crucial step for analyzing and synthesizing devices. In this thesis, we focus on wire medium (both isotropic and uniaxial) and validate a novel transport based model for them.

Scattering problems involving wire media are computationally intensive due to the spatially dispersive nature of homogenized wire media. However, it will be shown that using the new model to solve scattering problems can simplify the calculations a great deal.

For scattering problems, an integro-differential equation based on …

Speech Perception In Reverberated Condition By Cochlear Implants, Moulesh Bhandary

Theses and Dissertations

Previous Studies for bilateral cochlear implants users examined cocktail -party setting under anechoic listening conditions. However in real world listeners always encounter problems of reverberation, which could significantly deteriorate speech intelligibility for all listeners, independent of their hearing status.

The object of this study is to investigate the effects of reverberation on the binaural benefits for speech recognition by bilateral cochlear-implant (CI) listeners.

Bilateral CI subject was tested under different reverberation conditions. IEEE recorded sentences from one male speaker mixed with either speech shaped noise (ssn), energy masking, or with 2 female competing takers (2fsn), informational masking, at different signal …

Cryoimaging-Microscopy Implementation For 3d Optical Imaging, Mohammad Masoudimotlagh

Theses and Dissertations

The structures and biochemistry properties of biological tissues are mostly affected by diseases. The visualization of organ structure and biochemistry helps in early detection and progression monitoring of diseases.

Although, 2D imaging has traditionally been used to gain information from the tissue, it does not accurately represent many of the structures and functions. There currently exists a need for sensitive and specific methods to show detailed information about the structure of the tissue with high resolution and in 3D. The potential advantage of the high resolution 3D images is the ability to accurately probe structural and biochemical properties of the …

Optimal Dc Power Distribution System Design For Data Center With Efficiency Improvement, Xuechao Wang

Theses and Dissertations

Data Center Power Distribution design is very popular today focusing on improved energy efficiency and reduced operating cost. Conventionally data centers use low efficiency electrical power distribution systems with large AC power transformers, high power losses, and AC UPS and PDU power conversions. Most IT servers utilize low voltage level (12V or 48V) as the power source, which requires a step-down transformer and AC to DC rectifiers in every PDU. The "Proposed 380V DC Power Distribution System" promises to deliver high transmission efficiency and low power component cost.

This is a comprehensive design including data center physical architecture and equipment …

Coupled Electromagnetic And Thermal Analysis And Design Optimization Of Synchronous Electric Machines, Yi Wang

Theses and Dissertations

A new technique for coupling the electromagnetic, thermal, and air-flow analysis is proposed for electronically controlled synchronous machines. A computationally efficient finite element analysis (CE-FEA) technique is employed for the electromagnetic field analysis. An equivalent circuit network is used for thermal and air-flow analysis. An iterative algorithm, which exploits the fact that the type of machines studied have very low rotor losses and also a relatively reduced dependency of core losses with temperature and load, has been developed. The overall computational time is significantly reduced in comparison with the conventional coupling method, such that the new technique is highly suitable …

Short-Term Forecasting Of Wind Speed And Wind Power Based On Bp And Adaboost_Bp, Sibei Mi

Theses and Dissertations

Due to wind is intermittent and less dispatchable, wind power fluctuates as the wind fluctuating and is uncontrollable. Therefore, when wind power accounts for a higher proportion of total electricity generation of the system, power generation plan needs to arrange according to the variation of wind power output. The way to solve the problem is forecasting the wind power.

In this paper, we focus on the wind speed and wind power forecasting in the time scales of 10min, 1h and 3h in the future. BP Neural Network and Adaboost_BP Neural Network are selected as the forecasting model for wind speed …

Propagation Of An Optical Vortex In Fiber Arrays With Triangular Lattices, Muhammad Abdulrahman Mushref

Theses and Dissertations

The propagation of optical vortices (OVs) in linear and nonlinear media is an important field of research in science and engineering. The most important goal is to explore the properties of guiding dynamics for potential applications such as sensing, all-optical switching, frequency mixing and modulation. In this dissertation, we present analytical methods and numerical techniques to investigate the propagation of an optical vortex in fiber array waveguides. Analytically, we model wave propagation in a waveguide by coupled mode Equations as a simplified approximation. The beam propagation method (BPM) is also employed to numerically solve the paraxial wave Equation by finite …

Enhancement To Camera Calibration: Representation, Robust Statistics, And 3d Calibration Tool, Qiaotian Li

Theses and Dissertations

This thesis demonstrates theenhancement to camera calibrationin three aspects: representation of pose, robust statistics and 3D calibration tool. Camera calibration is the reconstruction of digital camera information based on digital images of an object in 3D space, since the digital images are 2D projections of a 3D object onto the camera sensor. Camera calibration is the estimation of the interior orientation (IO) parameters and exterior orientation (EO) parameters of a digital camera. Camera calibration is an essential part of image metrology. If the quality of camera calibration cannot be guaranteed, neither can the reliability of the subsequent analysis and applications …

System Theoretic Analysis Of Battery Equalization Systems, Haoqi Chen

Theses and Dissertations

Battery equalizers are widely used in multi-battery systems to maintain balanced charge among individual battery cells. While the research on the hardware realization of battery equalizers has received significant attention, rigorous analysis of battery equalization from the system's point of view remains largely unexplored. In this research, we study three types of battery equalization system structures: series-based, layer-based, and module-based. Specifically, we develop mathematical models that describe the system-level behavior of the battery equalization processes under these equalization structures. Then, based on the mathematical models, analytical methods are derived to evaluate the performance of the equalization processes. We also carry …

Design Of A Micro-Focus X-Ray Source Validated By Model Protein Crystals, Lavanya Ramachandran

Theses and Dissertations

The main objective of this thesis was to build a Laboratory Microfocus X-ray Source for Protein Crystallography (LMXS-PC), an X-ray source that would provide prospective users programmatic control and remote capability.

A study of the crystal was conducted using Photoactive Yellow protein (PYP) and cytochrome c nitrite reductase (ccNiR). The instrument was then tested by mounting the crystal in the instrument and collecting data.

The other objective of my research work was to determine the crystal structure of PYP using X-ray crystallography techniques. I attempted many trials in PYP crystal in an effort to achieve a high-quality diffraction pattern; however, …

Monitoring Changes In Hemodynamics Following Optogenetic Stimulation, Seth Thomas Frye

Theses and Dissertations

The brain is composed of billions of neurons, all of which connected through a vast network. After years of study and applications of different technologies and techniques, there are still more questions than answers when it comes to the fundamental functions of the brain. This project aims to provide a new tool which can be used to gain a better understanding of the fundamental mechanisms that govern neurological processes inside the brain. In order for neural networks to operate, blood has to be supplied through neighboring blood vessels. As such, the increase or decrease in the blood supply has been …

Optical Studies Of Oxidative Stress In Lung Tissue: Rodent Models, Reyhaneh Sepehr

Theses and Dissertations

Objectives: There currently exists a need for reliable measurements of tissue metabolic state at cellular levels. The objective of this research was to study tools capable of evaluating cellular redox states in intact tissue. To meet this goal, three different instruments (cryoimager, fluorometer, and fluorescent microscope) were used to study the metabolism and functions of the mitochondria at different levels and regimes (cryo, ex vivo, in vivo and in vitro).

Introduction: Through optical monitoring of autofluorescent mitochondrial metabolic coenzymes, as well as exogenous fluorophores, the state of mitochondria can be probed in real time in many intact organs and in …

Modeling And Protection Scheme For Ieee 34 Radial Distribution Feeder With And Without Distributed Generation, Sidharth Parmar Ashok

Theses and Dissertations

The existing power system was not designed with distribution generation (DG) in mind. As DG penetration is being considered by many distribution utilities, there is a rising need to address many incompatibility issues which puts a big emphasis on the need to review and implement suitable protection scheme. The usual practice for existing distribution feeders is the Overcurrent scheme which includes coordination between fuses and reclosers. But when DG is added to the distribution feeder, the configuration is no more radial as there is contribution of fault currents from the DG's and if the existing protection scheme is applied then …

Transverse Anderson Localization In Disordered Optical Fibers, Salman Karbasivalashani

Theses and Dissertations

In any wave-guiding system, disorder and randomness in the wave propagation medium are

considered as annoyances that result in wave scattering and inefficient wave transport. In contrast, in this work, the disorder is utilized in the transverse directions of an optical fiber for an effective light transport. The transversely disordered refractive index profile is invariant along the direction of propagation that results in transverse Anderson localization of light. A launched beam of light into the disordered fiber initially expands until it reaches the localization regime then propagates without further expansion in the transverse directions.

A disordered polymer optical fiber composed …