Engineering Commons^™

Formation Of Screen-Printed Contacts On Multicrystalline Silicon (Mc-Si) Solar Cells, Vishal R. Mehta

Dissertations

Commercial multicrystalline silicon (me-Si) solar cells use screen-printing process for depositing both the Ag paste based gridded front and Al based back (whole area) metal contacts.. This thesis relates to experimental and theoretical studies of contact formation mechanisms in silicon solar cells. Temperature distribution studies during optical processing by. attached thermocouples to cells indicates that the maximum temperature reached under the front silver metal is less. than 800°C; this is lower than the eutectic point of Ag-Si (≈835°C). An analysis of the interaction of Ag particles and Si via the constituents of glass is given. This mechanism leaches metallic ions …

Multi-Component Boron Coatings On Low Carbon Steel Aisi 1018, Naruemon Suwattananont

Dissertations

Boronizing and metalizing are thermo-chemical surface hardening treatments in which boron and metal atoms diffuse into the metal substrate forming metallic boride layers, providing complex properties of B-Me-Fe system.

To study multi-component boron coatings on low carbon steel AISI 1018, the simultaneous powder pack method of boronizing and metalizing was selected to perform the coatings. One B-Fe system and eight boron-metal (B-Me-Fe) systems from transition metals group IVB (Ti, Zr, Hf), group VB (Nb, Ta), and group VIB (Cr, Mo, W) were studied. The system specimens were thermo-chemically treated at 950°C for 4 hours in a crucible containing powder mixture …

Optimizing Integrated Service For A Transit Route With Heterogeneous Demand, Yavuz Yusuf Ulusoy

Dissertations

The methodology developed in this dissertation attempts to optimize integrated service that minimizes the total cost, including user and supplier costs, of a transit route with heterogeneous demand. While minimizing total cost, a set of practical constraints, such as capacity, operable fleet size and frequency conservation, are considered.

The research problem is presented in three scenarios, consisting of various service patterns (e.g., all-stop, short-turn and express) under heterogeneous demand. A logit-based model was used to estimate passenger transfer demand. An exhaustive search method was developed to find the optimal solutions for a simplified transit route with six stops, and a …

Mechanisms For Quality-Of-Service Provisioning In Networks With Extended Services, Zhen Qin

Dissertations

The emerging network traffic with various Quality-of-Service (QoS) requirements creates a demand for QoS service provisioning beyond the best effort service that Internet currently provides. QoS provisioning requires a framework that satisfies users' QoS and cost demand while maximizes benefits for network service providers. It is considered that QoS provisioning involves three issues: a) estimations of the network QoS performance, which can be achieved by performing network measurement; b) dissemination of the measured QoS states throughout the network with states exchanged among different network routers; and c) QoS routing. In this dissertation, these three issues are addressed.

In QoS networks, …

Coupled Simulation Of Loading And Response Of Columns Under Extreme Events, Navid H. Allahverdi

Dissertations

Forces imparted to structural columns during blast-induced loading depends on the shape and size of columns as well as on the intensity of the blast. Column's geometry - i.e., shape and size - influences the flow field around the column and consequently the flow field determines forces experienced by the column The main objective of this research is to estimate the forces imparted to columns in a blast event through studying the air flow field around columns

In this study, the physics of shock wave reflection and rarefaction waves are reviewed with application to describing the air flow around columns …

Design Of Drug Delivery Strategies Based On Well-Stirred Experiments, Kumud Kanneganti

Theses

Drugs are generally administered to the human body via injections (IV) or through other paths such as the buccal, nasal routes. The main consideration when designing a medication schedule is to maintain a therapeutic level of the drug in the body during the course of treatment. To achieve this goal, when IV drug therapy is selected, particular importance has to given to the dose to be injected and how to maintain the concentration of the pharmaceutical active ingredient (API) in the body between a Minimum Toxic Concentration (MTC) and a Minimum Effective Concentration (MEC). This therapeutic range varies with the …

Exploiting The Concept Of Hysteresis In Ankle Dysfunction And Ankle Strengthening, Akshay Narendra Pujara

Theses

The ankle joint is an important part of the body which is responsible for normal gait cycle. Dorsiflexion, plantar flexion, inversion and eversion are four types of movements controlled by the ankle joint. All these movements are controlled by the ligaments and the muscles associated with the ankle. Disorders of these ligaments and muscles leads to ankle dysfunction.

The hysteresis concept was employed to determine if there is any ankle dysfunction. A recently developed device, the Ankle Torsion Monitor (AnTm) was employed to evaluate the viscoelasticity and stiffness of the ankle joint. The greater the hysteresis loop area (HLA) the …

Axon Guided Axon Growth In Drg Neurons From The Spinal Cord Of Rat Embryos, Neha Jain

Theses

Early studies in the area of neuronal physiology and injury have shown that axons are guided by a number of physical as well as chemical cues. Although the guidance effect of initial axons and their processes on later axons has been shown from a development point of view, little light has been thrown on the subject from the injury point of view. This important ability of axons which plays a key role during development and formation of neuronal networks could become crucial in repairing damaged nerves and disrupted neuronal tracts.

In the following study, the guidance effect of an older …

Comparison Between Different Techniques Of Preprocessing For Resting State Fmri Analysis, Megha Girdhar

Theses

Resting state functional connectivity as the name suggests is defined as significant temporal correlation between spatially distinct regions of the brain during rest. In this thesis, fMRI resting state dataset was analyzed using different available processing techniques with the same fMRI data to study differences between the various methods. All the imaging data from each of the subjects was processed in an identical fashion. The same method was used for detecting connectivity. The number of independent components in the data was used as the base to differentiate the effect of each of these methods. Independent component analysis was performed on …

Interfacially Polymerized Thin Film Composite Membranes On Microporous Polypropylene Supports For Reverse Osmosis Desalination, Chao Li

Theses

The important technique of interfacial polymerization (IP) is used to fabricate thin film composite (TFC) membranes. In experiments here, microporous polypropylene (PP) flat film membranes were used as a support for fabricating TFC membranes for reverse osmosis by the IP technique. Substantial chemical, pH, and solvent resistance is provided by porous polypropylene membranes. Therefore, it is reasonable to choose porous polypropylene membranes as supports to fabricate TFC membranes for reverse osmosis.

The external and the pore surfaces of polypropylene flat film membrane were hydrophilized first by pre-wetting with acetone, then oxidized with chromic acid solution kept at 65°C. Next, the …

Effects Of Monoclonal Anti-Abeta Antibodies On The Amyloid Beta Peptide Fibrillogenesis And Their Involvement In The Clearance Of Alzheimer's Disease Plaques, Jeffy Pilar Jimenez

USF Tampa Graduate Theses and Dissertations

Alzheimer’s disease (AD) is the most common cause of senile dementia worldwide. AD is a neurodegenerative disorder characterized by the loss of memory and language skill, collapse of the cognitive function, and distortion of social behavior. As of today, the onset mechanisms of AD and cure are unknown; however, three hallmarks are commonly encountered: extra and intracellular accumulation of amyloid beta (A!) peptide plaques, formation of intracellular neurofibrillary tangles, and inevitable neuronal death. Hypothetically, a possible scenario provoking or involved in the onset of AD is a cascade effect that starts with an imbalance in the production and clearance of …

Ecotourism And Water Quality: Linking Management, Activities And Sustainability Indicators In The Caribbean, Ken Darrie Thomas

USF Tampa Graduate Theses and Dissertations

Ecotourism from its genesis and founding theories has been set out to conserve and preserve the environment through sustainable operation that includes surrounding communities in efforts to reduce their poverty levels. Over the years ecotourism has been hypothesized to have departed from this ideal with several researchers, through social, qualitative analyses, have said that these non-sustainable ecotourism operations are simply due to poor management. This work sought to test this central hypothesis as a first approach to quantitatively linking ecotourism activities to management with surface water quality as the key indicator of sustainable ecotourism as a complex system through systems …

Power Flow In Railway Electrification Power System, Sisi Li

Theses

This thesis discusses aspects of the design of the railway electrification system (RES) and in particular the electric distribution system for a 2x25 kV railway power system.

The analysis of Railway Power Supplies (RPS) presents a unique type of load flow problem which is characterized by its constant moving loads, dynamically changing load types (constant current/constant power), and its specialized network structure. The autotransformer power supply system with double track was the system studied in this thesis.

The details of the system studied were provided by Caltrain (California Commuter Rail) for a planned high speed extension to Caltrain system. A …

A Study Of Probability Distributions Of Dct Coefficients In Jpeg Compression, Gopal Thirumalai Narayanan

Theses

The Discrete Cosine Transform (DCT) used in JPEG compression has shown excellent energy compaction properties that rival that of the ideal Karhunen-Loève Transform. Lossy compression in JPEG is achieved by distorting 8x8 block DCT coefficients through quantization. It has been shown in literature that DC block DCT coefficients are Gaussian probability distributed and AC block DCT coefficients are Generalized Normal probability distributed.

In this investigation, three probability density models for individual modes of non- quantized AC block DCT coefficients are evaluated and are used as basis for the derivation of probability distributions for quantized block DCT coefficients. The suitability of …

Study Of Methods To Predict Voltage Collapse, Niki Patel

Theses

One of the problems that must be addressed for a secure power system operation is the voltage collapse problem. The ever increasing size and connectivity of the power grid have lead to making the problem more multifarious. Widespread blackouts, similar to the one that occurred in the northeast in August 2003, could result from failure to address the problem.

This thesis presents an overview of the voltage collapse problem and reviews some existing methods to calculate voltage collapse indicators.

Thevenin and Maximum Power Transfer Theorems are used to provide indicators of the proximity of the system to voltage collapse. The …

Air Piston Approach To Wave Power Generation, Arun Ramadass

Theses

Scientists have calculated that, by tapping just 0.2% of the energy produced by the world's oceans we can provide for all the worlds current energy needs. It is generally accepted that a combination of traditional energy production methods, (oil, coal, gas, nuclear) mixed with a combination of renewable energy production approaches is the future in providing for an increasingly energy hungry world. Wind, solar and biomass have moved into the public arena only in the last few years.

The proposed patented device (US Patent No.: 7,468,563) Ocean Wave Energy Converter harnesses the energy of ocean waves by continually raising and …

Minimum Agitation Speed For Solid Suspension And Mixing Time In A Torispherical -Bottomed Pharmaceutical Stirred Tank Under Different Baffling Conditions, Dilanji Bhagya Wijayasekara

Theses

The minimum agitation speed, NS, required to just suspend solid particles dispersed in water was experimentally determined in this work for a glass-lined type of mixing tank provided with a torispherical bottom and agitated with a retreat-blade impeller under different baffling configurations. Ns for the same tank but equipped with a different agitation system, namely an axial impeller, was also experimentally determined for the purpose of comparing of performances of the two systems. The effect of impeller off- bottom clearance and the vessel's liquid level on the minimum agitation speed were also experimentally studied. Njs, was experimentally determined …

Automation Of Anatomic Torsion Monitor For Evaluation And Improvement Of Low Back Dysfunction, Vishal Kumar Singh

Theses

The existing Anatomical Torsion Monitor (ATM) to evaluate mechanical stiffness and viscoelasticity of the low back suffers from various inherent defects. This has to be replaced by an improved device. Also the existing ATM cannot provide oscillations to the low back.

The main objective is to automate the existing ATM for evaluating the low back immediately using objective methods. The specific objective is to provide oscillations for improving the low back dysfunction.

The laser platform and the target chart for recording the readings are dispensed with the existing ATM. Instead, the ultrasound transducers are attached to the pads to record …

Papr Reduction In Ofdm Communications With Generalized Discrete Fourier Transform, Sertac Sayin

Theses

The main advantage of Generalized Discrete Fourier Transform (GDFT) is its ability to design a wide selection of constant modulus orthogonal code sets, based on the desired performance metrics mimicking the engineering specs of interest. One of the main drawbacks of Orthogonal Frequency Division Multiplexing (OFDM) systems is the high Peak to Average Power Ratio (PAPR) value which is directly related to power consumption of the system. Discrete Fourier Transform (DFT) spread OFDM technology, also known as Single Carrier Frequency Division Multiple Access (SCFDMA), which has a lower PAPR value, is used for uplink channel.

In this thesis, the PAPR …

A Comparison Of Software Engines For Simulation Of Closed-Loop Control Systems, Sanket D. Nikam

Theses

A wide array of control system design and simulation software engines is available in market. It includes MATLAB-Simulink, LabVIEW, Maple-MapleSim, Scilab-Scicos, VisSim and Mathematica-Control Professional Suite (CPS). Among all of them MATLAB-Simulink is dominant and widely used software engine. The main aim of this study is to implement different state space control methods for non-linear Furuta pendulum system in each one of them and to compare performance against MATLAB-Simulink.

Different parameters like learning curve, interoperability, flexibility, control design tools, documentation and tech support are considered for efficiency comparison. It is shown that MapleSim has multi-body intuitive physical modeling (acausal) approach …

Stochastic And Deterministic Dynamics Investigation Of The Microstructure Of Granular Materials, Vishagan Ratnaswamy

Theses

Granular materials are ubiquitous in one's daily life. They can be found in the cereal you eat, the sugar you put in your coffee or the sand you walk on in the beach. The study of granular materials has a rich history dating back to the 17th century where Kepler studied the packing of particles. The compaction of granular materials is a problem that is studied by using theory, experiments and simulations. While these studies have yielded some important results, there still are many details about the mechanisms of granular compaction that are unknown.

In this thesis, the density relaxation …

A Fpga/Dsp Based Ultrasound System For Tumor Detection, Ashish Ravindra Ratnakar

Theses

This work presents a method of detection of size and location of tumor using ultrasound transmission. The system utilizes Quantitative Ultrasound (QUS) which means sending an ultrasound signal from a transmitter and receiving it at multiple receivers. This received signal is analyzed for echogenic as well as echolucent tumors to differentiate between the two along with non-tumorous sample and also for delay, signal distortion to determine the size/location of the tumor.

This analysis is further implemented using Field Programmable Gate Array (FPGA) and Digital Signal Processor (DSP) technologies. The proposed detection system utilizes Low Transient Pulse (LTP) technique. In this …

Past Proceedings: First International Conference On Case Histories In Geotechnical Engineering (1984), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Past Proceedings: Third International Conference On Case Histories In Geotechnical Engineering (1993), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Past Proceedings: Third International Conference On Recent Advances In Geotechnical Earthquake Engineering And Soil Dynamics (1995), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Past Proceedings: Fifth International Conference On Recent Advances In Geotechnical Earthquake Engineering And Soil Dynamics (2010), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Past Proceedings: Second International Conference On Case Histories In Geotechnical Engineering (1988), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Past Proceedings: Fourth International Conference On Case Histories In Geotechnical Engineering (1998), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Past Proceedings: Fifth International Conference On Case Histories In Geotechnical Engineering (2004), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.

Past Proceedings: Sixth International Conference On Case Histories In Geotechnical Engineering (2008), Multiple Authors

International Conference on Case Histories in Geotechnical Engineering

No abstract provided.