Theses and Dissertations

This study aims at evaluating the performance of a company, 'XYZ Company', that has 115 service locations. Because of its ability of handling large numbers of inputs and outputs, and removing the need of predefining the factors' weights, Data Envelopment Analysis (DEA) is used. DEA is benchmark tool that measures the efficiency of entities with respect to each other by assessing their performance of utilizing inputs to produce outputs.

AbstractVarious strain-compensated InGaN-AlGaInN quantum well (QW) structures are investigated by self-consistent 6-band k∙p method, which considers valence band mixing, the strain effect, spontaneous and piezoelectric polarizations and the carrier screening effect, for their spontaneous emission and gain properties. The InGaN QW with In-content of 28% is sandwiched by AlGaInN barriers, which are Al0.2Ga0.8N, Al0.56Ga0.32In0.12N, Al0.72Ga0.13In0.15N, Al0.78Ga0.1In0.12N, and Al0.82Ga0.1In0.08N, with corresponding band gaps of 3.821eV, 4.156eV, 4.465eV, 4.765eV, and 5.065eV, respectively.

Nowadays CAD/CAM/CNC is widely used in all fields of manufacturing andproduction. With the help of them, ideas and designs can be quickly and accuratelybrought to reality. This thesis deals with manufacturing of rather complex high-strengthaluminum parts. The parts will be used for a new kind of alpine ski which incorporatessuspension with springs and dampeners. The requirements of the parts are quite typicalfor high-performance equipment - they need to be lightweight, strong, stiff, and aresubjected to various packaging constraints.

With the advent of nanotechnology, many fields of Engineering and Science took a leap to the next level of advancements. The broad scope of nanotechnology initiated many studies of heat transfer and thermal engineering. Nano-fluids are one such technology and can be thought of as engineered colloidal fluids with nano-sized colloidal particles. There are different types of nano-fluids based on the colloidal particle and base fluids. Nano-fluids can primarily be categorized into metallic, ceramics, oxide, magnetic and carbon based.

Renewable power generation resources are one of the biggest trends emerging thepower systems world. The inherent variability of these power sources brings chal-lenges in terms of planning, reliability and feasibility factors.

This work determines optimal planar geometric light source and optical imager configurations and electromagnetic wavelengths for maximizing the reflected signal intensity when using machine vision technology to image roadway markings with embedded spherical glass beads. It is found through a first set of experiments that roadway marking samples exhibiting little or no bead rolling effects are uniformly reflective with respect to the azimuthal angle of observation when measured for retroreflectivity within industry standard 30-meter geometry.

In response to the high cost and limited instrumentation available on commercial tribometers a student designed tribometer was conceived, built, and tested. This tribometer combines multiple tribology testing configurations into a single compact and reconfiguration tribometer, dubbed the multifunctional tribometer. This tribometer is also capable of operating in expanded experimental spaces not covered within the limited scope of industry standardized tribological tests.

Crosslinked epoxy resins have become popular materials in advanced engineering applications such as the aerospace, packaging, coatings, electrical, and adhesive industries. These resins offer a high strength to weight ratio, but have a drawback of being inherently brittle and exhibit poor flaw tolerance. In microelectronic packaging applications, the thermal expansion coefficients (CTEs) of neat epoxy resins are too high. The addition of inorganic fillers is a traditional solution for increasing fracture toughness and lowering CTE.

Tubular flange girders (TFG) are an innovative I-shaped steel bridge girder proposed for horizontally curved bridge systems. The I-shaped TFG has a steel tube flanges rather than a conventional flat plate flange for one or both flanges. The closed tube section significantly increases the torsional stiffness of the section and the open I-shaped section provides flexural stiffness.

With increase in the indoor usage of communication, there has been increase in the need for optimal design of mobile coverage for buildings with a lot of users. Cellular service companies had been pushing the limits with their macro-cell approach however, with the advent of 4G LTE and their higher frequency use, the penetration inside the buildings adds to their troubles. A Distributed Antenna System(DAS) extends the mobile coverage from the base station to distributed antennas through a network topology of coaxial cables and power splitters.

Acceleration is a basic concept in physics and engineering which is widely applied in fluid mechanics and vibration analysis. Recently, research has evolved to create a miniature device capable of measuring three components of acceleration. Electrical engineers have created a device called MinIMU-9 v2 that measures three components of acceleration. The system obtains acceleration components paralleling global (earth) coordinates. MinIMU-9 is designed to connect with an Arduino board (hardware) to maximize its functionality.

The human mind is very imprecise and uncertain most of the time. We are allowed to think as we wish, as things really are. This, however, is not how computers are designed to allow us to solve realistic problems. Now the question arises: how do we represent uncertainty and impreciseness using very accurate devices? In order to add flexibility into mechanical design, fuzzy logic can be used to represent the imprecise data, such as how humans think.

Cellular processes such as adhesion, proliferation, and differentiation are controlled in part by cell interactions with the microenvironment. Cells can sense and respond to a variety of stimuli, including soluble and insoluble factors (such as proteins and small molecules) and externally applied mechanical stresses. Mechanical properties of the environment, such as substrate stiffness, have also been suggested to play an important role in cell processes. The roles of both biochemical and mechanical signaling in fate modification of stem cells have been explored independently.

Wave energy and related devices have attracted more and more attention. The need for an accurate prediction system for ocean waveforms is urgent. Past research has involved the basic mathematical models and theories of predicting waveforms. The Cramer Rao Bound (CRB) is the key value to describe the accuracy of these models. The general form of the CRB has been derived in previous works, which also proposed several recommendations for the layout of sensors. However, the recommended layouts are not optimal, and the models do not capture the complicated ocean wave environment.

Styrenic block copolymers are one of the most used constituents in pressure sensitive adhesives due to their rubbery, yet viscous nature that allows them to flow out and adhere to substrates and yet have resiliency to resist creep. This study focused on high temperature performance benefits certain styrene-miscible or styrene-associating resins, referred to as styrenic block reinforcing additives (SBRAs), imparted to styrenic-block-copolymer-based pressure sensitive adhesives.

The major objective of this project is to design and implement a car guiding system in a desk-size area, with a remote-controlled toy car. The software, including the calculation, image processing, and movement control, was coded with Python and C++. Q-learning algorithm was selected to be the core of the calculation part, and OpenCV library was used for image processing.The hardware consists of a webcam, a laptop, and a toy car with Bluetooth connection.

The III-nitride material system has revolutionized the 21st century solid statelighting industry with the development of power-saving blue and white light-emitting diodes. Current research efforts into this material system include achieving highefficiency at longer wavelengths (green into red and beyond), the development of low-threshold current density and high gain solid state lasers, extending the capabilities of these materials into high voltage and current density power electronic devices, and reducing the cost of devices to compete with alternatives on the market.

Tissue engineering has a significant impact on biological and medical area. It helps to eventually realize the repair, replace or improve tissue function or even the complete organ. Inkjet cell printing, as a simple and novel way in bio-fabrication, is a promising tool to fabricate cell pattern and scaffolds that directly serve the purpose of tissue engineering.This thesis introduces a thermal inkjet cell printing device. The mechanical design, software and pertinent test data are described.

The Lehigh Ocean Research Craft Autonomous, or LORCA, was designed and built at Lehigh University's Composites Laboratory as a versatile unmanned boat, or Unmanned Surface Vehicle (USV). Ten 1.2m long boats have been built in various configurations, with the last seven built identically. The boat is fully self-righting with an enclosed electric motor, allowing it to be deployed in ocean conditions and rolled over without losing power or damaging equipment. Composite materials were used wherever possible in construction resulting in a craft that is strong, fast, and lightweight.

The history of the Lattice Boltzmann Method and its application to fluid mechanics are investigated here. Detailed formulations are provided to form a basis for the Lattice Boltzmann Method and its many variations. These variations are designed to overcome shortcomings in the standard single relaxation time Lattice Boltzmann model.

Neuronal cultures are widely used in neuroscience research. In vitro cell culture models have shown potential as drug testing platforms characterized by high throughput, low cost, good reproducibility and ease of handling and observation. However, in vitro neuronal culture models have been criticized for failure to capture important characteristics of in vivo models. For example, randomness of circuits in conventional in vitro cultures prevents accurate in vitro modeling of cortical development and of pathogenesis of neurological and psychiatric disorders.