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Articles 2941 - 2970 of 4566

Full-Text Articles in Engineering

The Nature Of Turbulence In A Narrow Apex Angle Isosceles Triangular Duct, Vaidyanathan Krishnan Jan 2007

The Nature Of Turbulence In A Narrow Apex Angle Isosceles Triangular Duct, Vaidyanathan Krishnan

Electronic Theses and Dissertations

An experimental investigation was performed to ascertain the nature of turbulence in a narrow apex angle isosceles triangular duct. The study involved the design and construction of a low noise, low turbulence wind tunnel that had an isosceles triangular test section with an apex angle of 11.5[degrees]. Experiments involved the measurement of velocity fluctuations using hot wire anemometry and wall pressure fluctuations using a condenser microphone. Measurement of the velocity fluctuations reconfirms the coexistence of laminar and turbulent regions at a given cross section for a range of Reynolds numbers. The laminar region is concentrated closer to the apex while …

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Mass Customization Strategies And Their Relationship To Lean Production In The Homebuilding Industry, Isabelina Nahmens Jan 2007

Mass Customization Strategies And Their Relationship To Lean Production In The Homebuilding Industry, Isabelina Nahmens

Electronic Theses and Dissertations

Current housing trends point to an increasing interest from homebuyers to demand houses that reflect their personal and unique styles, and which are individually configured according to these needs (NAHB, 2004). These homebuyers in turn are unwilling to settle for standard models that sacrifice what they really want in a home. At the same time this creates pressure on builders who are reluctant to sacrifice production efficiencies by deviating from standard models. Such customization desired by demanding customers can disrupt the entire estimating, production, delivery and management process, making it even more difficult to manage homebuilding efficiently and effectively. The …

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Zinc Cadmium Sulphide And Zinc Sulphide As Alternative Heterojunction Partners For Cigs2 Solar Cells, Bhaskar Kumar Jan 2007

Zinc Cadmium Sulphide And Zinc Sulphide As Alternative Heterojunction Partners For Cigs2 Solar Cells, Bhaskar Kumar

Electronic Theses and Dissertations

Devices with ZnCdS/ZnS heterojunction partner layer have shown better blue photon response due to higher band gap of these compounds as compared to devices with CdS heterojunction partner layer. CdS heterojunction partner layer has shown high photovoltaic conversion efficiencies with CIGS absorber layer while efficiencies are lower with CuIn1-xGaxS2 (CIGS2). A negative conduction band offset has been observed for CdS/CIGS2 as compared to near flat conduction band alignment in case of CdS/CIGS devices, which results in higher interface dominated recombination. Moreover, it has been predicted that optimum band offsets for higher efficiency solar cells may be achieved for cells with …

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Graph Theoretic Modeling: Case Studies In Redundant Arrays Of Independent Disks And Network Defense, Sanjeeb Nanda Jan 2007

Graph Theoretic Modeling: Case Studies In Redundant Arrays Of Independent Disks And Network Defense, Sanjeeb Nanda

Electronic Theses and Dissertations

Graph theoretic modeling has served as an invaluable tool for solving a variety of problems since its introduction in Euler's paper on the Bridges of Königsberg in 1736 . Two amongst them of contemporary interest are the modeling of Redundant Arrays of Inexpensive Disks (RAID), and the identification of network attacks. While the former is vital to the protection and uninterrupted availability of data, the latter is crucial to the integrity of systems comprising networks. Both are of practical importance due to the continuing growth of data and its demand at increasing numbers of geographically distributed locations through the use …

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Evaluation Of The Amazon Rain Forest As A Distributed Target For Satellite Microwave Radiometer Calibration, Nishant Patel Jan 2007

Evaluation Of The Amazon Rain Forest As A Distributed Target For Satellite Microwave Radiometer Calibration, Nishant Patel

Electronic Theses and Dissertations

For over three decades, satellite radars have used the Amazon tropical rain forest as a stable homogeneous and isotropic scattering target for calibration. This thesis extends previous work to consider the use of the Amazon as a blackbody target for passive microwave inter-satellite calibration. The characterization of a natural target for radiometric calibration is a formidable task due to the difficulty in obtaining an absolute brightness temperature standard. Previously, multi-frequency microwave brightness temperatures measured by the Tropical Rainfall Measuring Mission Microwave Imager (TMI) were used to provide multi-year observations in local time windows. Our approach differs in that we will …

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Comparison Of Thm Formation During Disinfection: Ferrate Versus Free Chlorine For Different Source Waters, Adhem Mukattash Jan 2007

Comparison Of Thm Formation During Disinfection: Ferrate Versus Free Chlorine For Different Source Waters, Adhem Mukattash

Electronic Theses and Dissertations

The objective of the study was to compare the trihalomethanes (THMs) produced from ferrate with hypochlorite and to determine how different the THM production would be for a given degree of disinfection (3 log reduction in Heterotrophic Plate Count (HPC)). Different water samples were collected from Lake Claire, Atlantic Ocean, and secondary effluent from an advanced wastewater treatment plant. THM formation was determined using a standard assay over 7 days at room temperature. In addition samples were tested for Total Coliform Escherichia coli (TC/E.coli), and heterotrophic bacteria using HPC by spreadplating on R2A agar. Dissolved organic carbon (DOC) was measured …

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Coalition Formation And Teamwork In Embodied Agents, Majid Ali Khan Jan 2007

Coalition Formation And Teamwork In Embodied Agents, Majid Ali Khan

Electronic Theses and Dissertations

Embodied agents are agents acting in the physical world, such as persons, robots, unmanned air or ground vehicles and so on. These types of agents are subject to spatio-temporal constraints, which do not exist for agents acting in a virtual environment. The movement of embodied agents is limited by obstacles and maximum velocity, while their communication is limited by the transmission range of their wireless devices. This dissertation presents contributions to the techniques of coalition formation and teamwork coordination for embodied agents. We considered embodied agents in three different settings, each of them representative of a class of practical applications. …

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Modeling, Design And Evaluation Of Networking Systems And Protocols Through Simulation, Daniel Jonathan Lacks Jan 2007

Modeling, Design And Evaluation Of Networking Systems And Protocols Through Simulation, Daniel Jonathan Lacks

Electronic Theses and Dissertations

Computer modeling and simulation is a practical way to design and test a system without actually having to build it. Simulation has many benefits which apply to many different domains: it reduces costs creating different prototypes for mechanical engineers, increases the safety of chemical engineers exposed to dangerous chemicals, speeds up the time to model physical reactions, and trains soldiers to prepare for battle. The motivation behind this work is to build a common software framework that can be used to create new networking simulators on top of an HLA-based federation for distributed simulation. The goals are to model and …

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A Method Of Content-Based Image Retrieval For The Generation Of Image Mosaics, Michael Snead Jan 2007

A Method Of Content-Based Image Retrieval For The Generation Of Image Mosaics, Michael Snead

Electronic Theses and Dissertations

An image mosaic is an artistic work that uses a number of smaller images creatively combined together to form another larger image. Each building block image, or tessera, has its own distinctive and meaningful content, but when viewed from a distance the tesserae come together to form an aesthetically pleasing montage. This work presents the design and implementation of MosaiX, a computer software system that generates these image mosaics automatically. To control the image mosaic creation process, several parameters are used within the system. Each parameter affects the overall mosaic quality, as well as required processing time, in its own …

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Extending Distributed Temporal Protocol Logic To A Proof Based Framework For Authentication Protocols, Shahabuddin Muhammad Jan 2007

Extending Distributed Temporal Protocol Logic To A Proof Based Framework For Authentication Protocols, Shahabuddin Muhammad

Electronic Theses and Dissertations

Running critical applications, such as e-commerce, in a distributed environment requires assurance of the identities of the participants communicating with each other. Providing such assurance in a distributed environment is a difficult task. The goal of a security protocol is to overcome the vulnerabilities of a distributed environment by providing a secure way to disseminate critical information into the network. However, designing a security protocol is itself an error-prone process. In addition to employing an authentication protocol, one also needs to make sure that the protocol successfully achieves its authentication goals. The Distributed Temporal Protocol Logic (DTPL) provides a language …

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Redistribution Of Manganese Ion Implanted In Silicon, Arun Kumar Shunmugavelu Jan 2007

Redistribution Of Manganese Ion Implanted In Silicon, Arun Kumar Shunmugavelu

Electronic Theses and Dissertations

Ion implantation and the subsequent redistribution of manganese atoms in Czochralski Silicon (Cz-Si) and Floating Zone Silicon (Fz-Si) due to thermal annealing between 300 C and 1000 C is studied using Secondary Ion Mass Spectroscopy. The samples ion implanted at 340 C showed multiple peak formation above 900 C. This was not observed for the samples ion implanted at room temperature. Cz-Si and Fz-Si showed similar redistribution profiles.

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Microwave Synthesis Of Nanocrystalline Hydroxy Apatite And Comparison Of Its Biomechanical Properties With Tio2 Structures, Saurabh Verma Jan 2007

Microwave Synthesis Of Nanocrystalline Hydroxy Apatite And Comparison Of Its Biomechanical Properties With Tio2 Structures, Saurabh Verma

Electronic Theses and Dissertations

Nanocrystalline hydroxyapatite (HAp) powder of size 10-20 nm was synthesized applying microwave radiation using calcium nitrate tetrahydrate and sodium phosphate dibasic anhydrous as the starting materials. Microwave power of 600 W and Ca/P ratio of 1.66 in the starting chemicals served as the major factors in the synthesis of nanocrystalline HAp powder. Phase composition and evolution were studied using X-ray diffraction (XRD) technique. Morphology, agglomeration and particle-size of the synthesized powder were studied using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques. Energy Dispersive Spectrum (EDS) was used to determine the elemental composition of the powder. Thermal properties …

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Steady State And Dynamic Analysis And Optimization Of Single-Stage Power Factor Correction Converters, Khalid Rustom Jan 2007

Steady State And Dynamic Analysis And Optimization Of Single-Stage Power Factor Correction Converters, Khalid Rustom

Electronic Theses and Dissertations

With the increased interest in applying Power Factor Correction (PFC) to off-line AC-DC converters, the field of integrated, single-stage PFC converter development has attracted wide attention. Considering the tens of millions of low-to-medium power supplies manufactured each year for today's rechargeable equipment, the expected reduction in cost by utilizing advanced technologies is significant. To date, only a few single-stage topologies have made it to the market due to the inherit limitations in this structure. The high voltage and current stresses on the components led to reduced efficiency and an increased failure rate. In addition, the component prices tend to increase …

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A Neat Approach To Genetic Programming, Adelein Rodriguez Jan 2007

A Neat Approach To Genetic Programming, Adelein Rodriguez

Electronic Theses and Dissertations

The evolution of explicitly represented topologies such as graphs involves devising methods for mutating, comparing and combining structures in meaningful ways and identifying and maintaining the necessary topological diversity. Research has been conducted in the area of the evolution of trees in genetic programming and of neural networks and some of these problems have been addressed independently by the different research communities. In the domain of neural networks, NEAT (Neuroevolution of Augmenting Topologies) has shown to be a successful method for evolving increasingly complex networks. This system's success is based on three interrelated elements: speciation, marking of historical information in …

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Dynamic Speed Monitoring System Effectiveness On Sharp Curves, Vasu Tavasna Persaud Jan 2007

Dynamic Speed Monitoring System Effectiveness On Sharp Curves, Vasu Tavasna Persaud

Electronic Theses and Dissertations

The design of rural interchanges is of critical concern due to the need for the safe transition of vehicles from one high speed roadways to another and vice versa. This transition is accomplished by entry and exit ramps of various forms. The southbound entry loop ramp at the US 27/ US 192 trumpet interchange in Polk County, Florida does not provide such safe transition since historically there has been a high incidence of vehicular off-tracking. The geometry of the southbound entry ramp coupled with high approach speeds are two of the contributing factors. Due to the high cost of interchange …

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Optimizing The Design Of Multimodal User Interfaces, Leah Reeves Jan 2007

Optimizing The Design Of Multimodal User Interfaces, Leah Reeves

Electronic Theses and Dissertations

Due to a current lack of principle-driven multimodal user interface design guidelines, designers may encounter difficulties when choosing the most appropriate display modality for given users or specific tasks (e.g., verbal versus spatial tasks). The development of multimodal display guidelines from both a user and task domain perspective is thus critical to the achievement of successful human-system interaction. Specifically, there is a need to determine how to design task information presentation (e.g., via which modalities) to capitalize on an individual operator's information processing capabilities and the inherent efficiencies associated with redundant sensory information, thereby alleviating information overload. The present effort …

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Methods Of Extrapolating Low Cycle Fatigue Data To High Stress Amplitudes, David Charles Radonovich Jan 2007

Methods Of Extrapolating Low Cycle Fatigue Data To High Stress Amplitudes, David Charles Radonovich

Electronic Theses and Dissertations

Modern gas turbine component design applies much effort into prediction and avoidance of fatigue. Advances in the prediction of low-cycle fatigue (LCF) cracks will reduce repair and replacement costs of turbine components. These cracks have the potential to cause component failure. Regression modeling of low-cycle fatigue (LCF)test data is typically restricted for use over the range of the test data. It is often difficult to characterize the plastic strain curve fit constants when the plastic strain is a small fraction of the total strain acquired. This is often the case with high strength, moderate ductility Ni-base superalloys. The intent of …

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Cognitive Learning From Computer-Based Information Systems By Incorporating Knowledge Construction Interventions, Wajdi Wazzan Jan 2007

Cognitive Learning From Computer-Based Information Systems By Incorporating Knowledge Construction Interventions, Wajdi Wazzan

Electronic Theses and Dissertations

The aim of the present study was to develop and empirically evaluate different categories of instructional activities, which stimulate the generation and construction of knowledge on the part of an individual student. These generative activities are primed by prompts or scaffolds, which can easily be inserted into specific curriculum addressing any domain of knowledge. To assess the manner in which the knowledge construction interventions influence the learning outcomes from computerized information systems, we have developed an online computer-based information system that describes the functions and mechanisms associated with the bus system of the US army Abrams M1A2 tank. Seven versions …

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Reversion Of Poly-Phosphates To Ortho-Phosphates In Water Distribution Systems, Avinash Shekhar Jan 2007

Reversion Of Poly-Phosphates To Ortho-Phosphates In Water Distribution Systems, Avinash Shekhar

Electronic Theses and Dissertations

Orthophosphates and polyphosphates are rarely present at significant levels in raw water source but are purposefully added to the water in various forms to inhibit corrosion, iron oxidation (red water), or calcium carbonate precipitation (scale formation). Orthophosphates serve as building blocks for polyphosphates, which includes structures in linear chain, branched chains (metaphosphate) and "glassy" polyphosphate polymers. The advantage of polyphosphates over ortho phosphates lies in the fact that they slowly revert to orthophosphates and thus provide corrosion inhibition action over longer period of time in distribution systems. A study was completed for Tampa Bay Water on water distribution systems in …

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Temperature Inside The Landfill: Effects Of Liquid Injection And Ambient Temperature, Amit Kumar Jan 2007

Temperature Inside The Landfill: Effects Of Liquid Injection And Ambient Temperature, Amit Kumar

Electronic Theses and Dissertations

This study represents an analysis of comprehensive temperature and moisture content data collected from the anaerobic portion of a bioreactor landfill at the New River Regional Landfill, Florida, USA. The main focus of the study was the analysis of effects of the liquid injection on the temperature inside the landfill. When the leachate or groundwater at lower temperature than the landfilled waste is injected into the landfill, it has an initial cooling effect on the waste until the biological activity, enhanced by the additional moisture, releases heat. This cooling effect was tested in the study to determine whether it could …

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Film Growth Of Novel Frequency Agile Complex-Oxide Piezoelectric Material, Bindu Sreeramakavacham Jan 2007

Film Growth Of Novel Frequency Agile Complex-Oxide Piezoelectric Material, Bindu Sreeramakavacham

Electronic Theses and Dissertations

Piezoelectric materials are well known for their applications in surface (SAW) and bulk acoustic wave (BAW) devices such as oscillators, resonators and sensors. Quartz has been the main material used in such applications. Ternary calcium gallium germanate (CGG) structure-type materials, so-called langasites, recently emerged as very promising because of their piezoelectric properties superior to quartz. This thesis discusses the growth of langasite-type La3Ga5.5Ta0.5O14 (LGT) films by liquid phase epitaxy (LPE) technique and their chemical and structural characterization. In addition, the different techniques suitable for the growth of LGT are discussed and compared. To adjust the materials properties for given applications, …

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Investigation Of Pn Junction Delineation Resolution Using Electron Beam Induced Current, Christopher Hayden Hontgas Jan 2007

Investigation Of Pn Junction Delineation Resolution Using Electron Beam Induced Current, Christopher Hayden Hontgas

Electronic Theses and Dissertations

This dissertation will investigate electron beam induced current (EBIC) for determining semiconductor material and device parameters. While previous experimental work on PN junction delineation using EBIC with the scanning electron microscope has resulted in resolution to approximately 10 nm, theoretical study shows the potential use of EBIC for higher resolution (nanometer) PN junction and FET channel length delineation using the transmission electron microscope. Theoretical arguments using computer simulations of electron beam generation volume, collection probability and EBIC were performed and are presented for the purpose of determining EBIC use in a 300 keV transmission electron microscope (TEM) for PN junction …

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Mac Layer And Routing Protocols For Wireless Ad Hoc Networks With Asymmetric Links And Performance Evaluation Studies, Guoqiang Wang Jan 2007

Mac Layer And Routing Protocols For Wireless Ad Hoc Networks With Asymmetric Links And Performance Evaluation Studies, Guoqiang Wang

Electronic Theses and Dissertations

In a heterogeneous mobile ad hoc network (MANET), assorted devices with different computation and communication capabilities co-exist. In this thesis, we consider the case when the nodes of a MANET have various degrees of mobility and range, and the communication links are asymmetric. Many routing protocols for ad hoc networks routinely assume that all communication links are symmetric, if node A can hear node B and node B can also hear node A. Most current MAC layer protocols are unable to exploit the asymmetric links present in a network, thus leading to an inefficient overall bandwidth utilization, or, in the …

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Supersonic Crossflow Visualization Using The University Of Central Florida Supersonic Wind Tunnel, Peter Himmerich Jan 2007

Supersonic Crossflow Visualization Using The University Of Central Florida Supersonic Wind Tunnel, Peter Himmerich

Electronic Theses and Dissertations

The next generation air breathing engine that would enable an alternative to conventional air travel or suborbital flight is the supersonic ramjet engine (SCRAM) which requires a highly accelerated rate of fuel mixing and combustion. For this type of engine, one of the improvement opportunities lies in the injection of the fuel into the supersonic flow inside the combustor. In order to determine the flow field that develops when a sonic jet of secondary gas is injected into a supersonic free stream, a dedicated test section was developed which was attached to the existing supersonic wind tunnel at the University …

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Multi-View Geometric Constraints For Human Action Recognition And Tracking, Alexei Gritai Jan 2007

Multi-View Geometric Constraints For Human Action Recognition And Tracking, Alexei Gritai

Electronic Theses and Dissertations

Human actions are the essence of a human life and a natural product of the human mind. Analysis of human activities by a machine has attracted the attention of many researchers. This analysis is very important in a variety of domains including surveillance, video retrieval, human-computer interaction, athlete performance investigation, etc. This dissertation makes three major contributions to automatic analysis of human actions. First, we conjecture that the relationship between body joints of two actors in the same posture can be described by a 3D rigid transformation. This transformation simultaneously captures different poses and various sizes and proportions. As a …

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Management Systems Fit For Organizational Performance, Rey Diaz Jan 2007

Management Systems Fit For Organizational Performance, Rey Diaz

Electronic Theses and Dissertations

The present study identifies the dimensions and variables using prior research within each of the constructs under the management systems, fit and, organizational strategy, structure, lifecycle and performance. The constructs from the research model were defined with a combination of direct, calculated and coded measures. Context analysis for each case categorized management systems design into either prescriptive or descriptive. The selected performance measures have been extensively investigated in the research fields associated with organizational management. The study uses the multiple case study design with cross-sectional data spanning from 1991 to 2005 and involving 19 aerospace companies in the United States. …

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Using Electrochemical Monitoring To Predict Metal Release In Drinking Water Distribution Systems, Rajendra D. Vaidya Jan 2007

Using Electrochemical Monitoring To Predict Metal Release In Drinking Water Distribution Systems, Rajendra D. Vaidya

Electronic Theses and Dissertations

Corrosion of distribution system piping and home plumbing materials is a major concern in the water community. Iron release adverse affects aesthetic water quality and the release of copper and lead is regulated by the Lead and Copper rule (LCR) and can adversely affect consumer health. Corrosion control is typically done by pH regulation and/or addition of corrosion inhibitors. Monitoring of corrosion control is typically done after the fact by monitoring metal release, functional group concentration of the selected chemical species or water quality. Hence, the associated laboratory analyses create a significant delay prior to the assessment of corrosion in …

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Effect Of Horizontal Piles On The Soil Bearing Capacity For Circular Footing Above Cavity, Rafael L. Arosemena Jan 2007

Effect Of Horizontal Piles On The Soil Bearing Capacity For Circular Footing Above Cavity, Rafael L. Arosemena

Electronic Theses and Dissertations

The design of foundation in normal soil conditions is governed by bearing capacity, minimum depth of foundation and settlement. However, foundation design in karst regions needs to consider an additional criterion associated to the possibility of subsurface subsidence and ravelling sinkholes. Under this environment, alternative techniques are needed to improve the subsurface soil. In this study general background information is given to understand the geological characteristics of Central Florida and why this area is considered to be a karst region and susceptible to sinkholes formation. Traditional foundation design techniques on karst regions are addressed in this paper. Finally, the use …

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Controls Algorithm For A Satellite Using Earth's Magnetic Field: Orbit Maneuvers And Attitude Positioning, Karthik Ganesh Jan 2007

Controls Algorithm For A Satellite Using Earth's Magnetic Field: Orbit Maneuvers And Attitude Positioning, Karthik Ganesh

Electronic Theses and Dissertations

This document describes the design, analysis of Orbit Maneuvers and Attitude Control for NanoSat class satellites, which uses an electro-magnetic force controller which was proposed by the Florida Space Institute (FSI). Orbit Maneuvering and the Attitude Control System (ACS) play a very important role for the success of this mission, as that can allow making the satellite go to the desired orbit as well do the sun pointing of the solar arrays with su¢ cient accuracy to achieve desired power levels. The primary mission would be to attain attitude stabilization using the torque from the coils. This is also used …

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Hybrid Photonic Signal Processing, Farzan Naseer Ghauri Jan 2007

Hybrid Photonic Signal Processing, Farzan Naseer Ghauri

Electronic Theses and Dissertations

This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an …

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