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2009

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Articles 31 - 60 of 4610

Full-Text Articles in Engineering

Non-Darcy Flow And Heat Transfer In A Porous Insulation With Infiltration, Hwa-Chong Tien, Kwang-Sheng Chiang Dec 2009

Non-Darcy Flow And Heat Transfer In A Porous Insulation With Infiltration, Hwa-Chong Tien, Kwang-Sheng Chiang

Journal of Marine Science and Technology

This work analyzes non-Darcy flow and heat transfer in a vertical slot filled with a porous matrix. The left and right vertical boundaries of the porous system are maintained at higher and lower temperatures, respectively. The horizontal boundaries are assumed to be impermeable and insulated. The vertical boundaries are either completely impermeable, where free convection is induced, or partially permeable in a way to simulate the wall leakage in the building materials, where both air infiltration and free convection exist. The non-Darcy model, which includes the Brinkman and Forchheimer extensions along with the convection terms, is employed to describe the …

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Robust Stability Bounds For Lur'e System With Parametric Uncertainty, Chyun-Chau Fuh, Pi-Cheng Tung Dec 2009

Robust Stability Bounds For Lur'e System With Parametric Uncertainty, Chyun-Chau Fuh, Pi-Cheng Tung

Journal of Marine Science and Technology

The robust stability of Lur’e system with parametric uncertainty is studied through the Popov-Lyapunov approach. Robust stability bounds of such a system are presented. Since we avoid using norm forms and absolute values, the obtained stability bounds are less conservative. An example demonstrating the feasibility of our method is illustrated

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Self-Organized Nanolayers Of Organosilane Molecules, Ocelio V. Lima Dec 2009

Self-Organized Nanolayers Of Organosilane Molecules, Ocelio V. Lima

Engineering Mechanics Dissertations & Theses

There is a high degree of interest in organic thin films for lightweight, low power, rugged and flexible electronics. Conjugated organic molecules with polycyclic rings are being considered a major enabler of such applications. Due to a surface tension mismatch between the organic molecule with the inorganic support (mainly silicon oxides), molecular packing inside these thin films is often disordered, which suppresses the device performance. There are major efforts focused on modifying the bulk properties, for instance, maximizing orbital overlaps in the solid state, little attention was paid to receive long-range ordered thin films. A novel approach to afford conjugated …

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Development Of A Methodology For Numerical Simulation Of A D C Arc Discharge In A Liquid Dielectric, Christopher James Lewis Dec 2009

Development Of A Methodology For Numerical Simulation Of A D C Arc Discharge In A Liquid Dielectric, Christopher James Lewis

Theses and Dissertations

The majority of literature regarding the numerical simulation of arc discharges in gaseous environments has used a plasma physics approach. Virtually all simulations treat the discharge as an idealized gaseous plasma, which can be described by temperature, pressure, and electric field. This approach can work well if the media is a shielding gas such as Argon; however, the approach does not work well for processes such as underwater welding, EDM, and underwater discharges used to generate high purity particles. The reason these discharges do not have many extensive simulation efforts as described in the literature is because they occur in …

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Spanning Trees For Binary Directed De Bruijn Networks And Their Applications To Load Balancing, Ming-Bo Lin, Ming-Hong Bai, Gene Eu Jan Dec 2009

Spanning Trees For Binary Directed De Bruijn Networks And Their Applications To Load Balancing, Ming-Bo Lin, Ming-Hong Bai, Gene Eu Jan

Journal of Marine Science and Technology

One of the major reasons of using parallel computer systems is that they have the potential for improving performance and resource sharing. To achieve this, an efficient way must be provided to broadcast a message or messages from a node to every other nodes in the system. However, the efficiency of transferring messages in a system is determined by the architecture of the underlying interconnection network of the system. In this paper, we consider the systems based on binary directed de Bruijn networks and define two shortest path spanning trees: the upward-0 spanning tree and the downward-0 spanning tree, to …

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Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung Dec 2009

Design Of A Fuzzy Gain Scheduling Controller Having Input Saturation: A Comparative Study, Yan-Wen Huang, Pi-Cheng Tung

Journal of Marine Science and Technology

A fuzzy gain scheduling proportional controllers that exhibits the improved performance than the conventional linear fixed gain controller having input saturation is proposed in this paper. We proposed an adaptive anti-windup control system in which the gain of a proportional controller is dynamically tuned by a fuzzy PD system. The methodology employed in the analysis is based on the describing function (DF), which is determined the range of the universal discourse for the output of the fuzzy PD system. Other approaches are the linear quadratic regulator (LQR) method and combined back-calculation and generalized conditioning anti-windup. In this paper, a comparison …

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Design And Implementation Of Dstatcom For Fast Load Compensation Of Unbalanced Loads, Wei-Neng Chang, Kuan-Dih Yeh Dec 2009

Design And Implementation Of Dstatcom For Fast Load Compensation Of Unbalanced Loads, Wei-Neng Chang, Kuan-Dih Yeh

Journal of Marine Science and Technology

This paper proposes a distribution level static synchronous compensator (DSTATCOM) for fast load compensation of unbalanced loads in electric power distribution systems. For fast response requirement, a new feedforward compensation scheme is derived and employed in the paper. First, the compensation scheme of the DSTATCOM is derived with the symmetrical components method. Then, computer simulation with the program Matlab/Simulink preliminarily verifies the effectiveness of the proposed DSTATCOM. Accordingly, a hardware prototype is built with a floating-point DSP TMS320C6711-based system. Use of a current-regulated PWM (CRPWM) inverter as the power stage of the DSTATCOM generates needed compensation currents for real-time load …

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Dsp-Based Implementation Of A Real-Time Doa Estimator For Underwater Acoustic Sources, Sheng-Yun Hou, Shun-Hsyung Chang, Hsien-Sen Hung, Jiang-Yao Chen Dec 2009

Dsp-Based Implementation Of A Real-Time Doa Estimator For Underwater Acoustic Sources, Sheng-Yun Hou, Shun-Hsyung Chang, Hsien-Sen Hung, Jiang-Yao Chen

Journal of Marine Science and Technology

Many direction-of-arrival (DOA) estimation algorithms for acoustic sources based on sensor array measurements have been well developed and verified via computer simulations and/or small-scale water trough experiments. However, these results are not in practical use because the testing scenarios may not reflect real underwater environments. In order to have a better understanding of DOA estimation in sea experiments, a prototype of DSP-based acoustic DOA estimator is designed and implemented. The prototype system is based on TMS320VC33 digital signal processor and is validated by both computer simulation and experiments performed on the shallow water of Bi-Sha fishery harbor located near the …

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Cpt-Based Simplified Liquefaction Assessment By Using Fuzzy-Neural Network, Shuh-Gi Chern, Ching-Yinn Lee Dec 2009

Cpt-Based Simplified Liquefaction Assessment By Using Fuzzy-Neural Network, Shuh-Gi Chern, Ching-Yinn Lee

Journal of Marine Science and Technology

Due to the difficulty and the cost of obtaining high quality undisturbed samples, simplified methods based on in-situ tests such as the standard penetration test (SPT) and the cone penetration test (CPT) are preferred by geotechnical engineers for evaluation of earthquake induced liquefaction potential of soils. Because of the increasing popularity worldwide of the CPT for site characterization, significant progress on the CPTbased methods has been made. In most existing CPT-based methods, empirically determined curves are used to predict liquefaction and non-liquefaction. These empirical curves are generally relied on engineering judgment and are essentially performance functions that were established based …

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Fundamental Properties Of Linear Ship Steering Dynamic Models, Ching-Yaw Tzeng, Ju-Fen Chen Dec 2009

Fundamental Properties Of Linear Ship Steering Dynamic Models, Ching-Yaw Tzeng, Ju-Fen Chen

Journal of Marine Science and Technology

This paper is concerned with the fundamental properties associated with the Nomoto models. Specifically, the state space model associated with the first order Nomoto model is both observable and controllable. The state space model associated with the second order Nomoto model is also observable; however, it is controllable only if the effective sway time constant is different from the effective yaw time constant. The zero appearing in the transfer function model is found responsible for the overshoot behaviors, which are typical in the yaw rate for large rudder angle steering. This suggests that a second order Nomoto model is more …

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The Construction Common Product Coding System And Auto Id Technology In Construction, Nai-Hsin Pan Dec 2009

The Construction Common Product Coding System And Auto Id Technology In Construction, Nai-Hsin Pan

Journal of Marine Science and Technology

Automatic data identification (Auto ID) technology such as bar code has grown rapidly in various industries. During the last couple of years, a small number of construction companies have also started to implement Auto ID technologies for a limited number of applications. The focus of these applications has primarily been limited to the internal operations of a few larger companies. One of the major barriers to adopt modern Auto ID technologies in the construction industry is the lack of Construction Common Product Code System (CCPCS). The main objective of this research is to investigate the problems created by inadequate CCPCS …

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A Novel Stability Condition And Its Application To Ga-Based Fuzzy Control For Nonlinear Systems With Uncertainty, Po-Chen Chen, Cheng-Wu Chen, Wei-Ling Chiang, Ken Yeh Dec 2009

A Novel Stability Condition And Its Application To Ga-Based Fuzzy Control For Nonlinear Systems With Uncertainty, Po-Chen Chen, Cheng-Wu Chen, Wei-Ling Chiang, Ken Yeh

Journal of Marine Science and Technology

In this study, we strive to combine the advantages of fuzzy logic control (FLC), genetic algorithms (GA), H∞ tracking control schemes, smooth control and adaptive laws to design an adaptive fuzzy sliding model controller for the rapid and efficient stabilization of complex and nonlinear systems. First, we utilize a reference model and a fuzzy model (both involving FLC rules) to describe and well-approximate an uncertain, nonlinear plant. The FLC rules and the consequent parameter are decided on via GA. A boundary-layer function is introduced into these updated laws to cover modeling errors and to guarantee that the state errors converge …

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Service Life Prediction Of Pier For The Existing Reinforced Concete Bridges In Chloride-Laden Environment, Ming-Te Liang, Ran Huang, Shen-An Feng, Chi-Jang Yeh Dec 2009

Service Life Prediction Of Pier For The Existing Reinforced Concete Bridges In Chloride-Laden Environment, Ming-Te Liang, Ran Huang, Shen-An Feng, Chi-Jang Yeh

Journal of Marine Science and Technology

The prediction method of service life for bridge structures is played an important role of bridge management system. In this paper, the mathematical modeling was to study the servise life prediction of pier for existing reinforced concrete (RC) bridge exposed to chloride environment. The corrosion process has three stages, the initiation time (tc), the depassivation time (tp), and the corrosion (propagation) time (tcorr). The total service life of pier for the existing RC bridge can be expressed as t = tc + tp + tcorr. Many mathematical models were applied to predicting each value of the tc, tp, and tcorr. …

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Passive Earth Pressures On A Pile Cap With A Dense Sand Backfill, Robert Ashall Marsh Dec 2009

Passive Earth Pressures On A Pile Cap With A Dense Sand Backfill, Robert Ashall Marsh

Theses and Dissertations

Pile groups are often used to provide support for structures. Capping a pile group further adds to the system's resistance due to the passive earth pressure from surrounding backfill. While ultimate passive earth pressure under static loading conditions can be readily calculated using several different theories, the effects of cyclic and dynamic loading on the passive earth pressure response are less understood. Data derived from the full-scale testing of a pile cap system with a densely compacted sand backfill under static, cyclic, and dynamic loadings was analyzed with particular focus on soil pressures measured directly using pressure plates. Based on …

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Manifest Greatness Version5 By Marc Guerrero With Tato Malay, Emmanuel Mario B. Santos Aka Marc Guerrero Dec 2009

Manifest Greatness Version5 By Marc Guerrero With Tato Malay, Emmanuel Mario B. Santos Aka Marc Guerrero

Emmanuel Mario B Santos aka Marc Guerrero

MANIFEST GREATNESS version5 by Marc Guerrero with Tato Malay

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Computational Modeling Of Biochemical Systems Using Cellular Automata, Advait Apte Dec 2009

Computational Modeling Of Biochemical Systems Using Cellular Automata, Advait Apte

Theses and Dissertations

Biological systems exhibit complex behaviors through coordinated responses of individual biological components. With the advent of genome-scale techniques, one focus has been to develop methods to model interactions between components to accurately describe intact system function. Mathematical modeling techniques such as constraint-based modeling, agent-based modeling, cellular automata (CA) modeling and differential equation modeling are employed as computational tools to study biological phenomenon. We have shown that cellular automata simulations can be used as a computational tool for 12 predicting the dynamics of biological systems with stochastic behavior. The basic premise for the research was the observations made during a study …

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Energy Dissipation Caused By Asphalt Roadway Gouges For Use In Accident Reconstruction, Charles L. Crosby Dec 2009

Energy Dissipation Caused By Asphalt Roadway Gouges For Use In Accident Reconstruction, Charles L. Crosby

Theses and Dissertations

In reconstruction of on-roadway vehicle accidents, roadway surface gouges and the forces and energy attributed to the related vehicle components become important keys to resolving an accurate accident reconstruction. These roadway gouge forces vary depending upon such factors as surface temperature and the velocity and geometry of the gouging mechanism. Accounting for the forces applied to vehicle components and the energy dissipated from such forces can be helpful in accident reconstruction where supporting data exists. This research documents the force necessary to create a given roadway gouge geometry. Controlled pavement gouging tests were performed using roadway surface temperature and gouging …

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Should Tortuosity Still Be Used In Upscaling?, Francisco J. Valdes-Parada, Mark L. Porter, Brian D. Wood Dec 2009

Should Tortuosity Still Be Used In Upscaling?, Francisco J. Valdes-Parada, Mark L. Porter, Brian D. Wood

Francisco J. Valdes-Parada

The concept of tortuosity is an integral part of models that describe trans- port in multiscale systems. Traditionally, tortuosity is de#12;ned as the ratio of an e#11;ective path length to the shortest path length in a representative sample of the porous medium microstructure. While the latter can be unambiguously speci#12;ed, the same is not true for the e#11;ective path length, since it changes from one type of transport to another. Consequently, it is possible to have di#11;erent tortuosity values for di#11;erent transport processes taking place in the same system. In order to avoid running into unclear interpretations, we pro- pose …

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Smes And Virtual R&D Teams: A Motive Channel For Relationship Between Smes, Nader Ale Ebrahim, Shamsuddin Ahmed, Zahari Taha Dec 2009

Smes And Virtual R&D Teams: A Motive Channel For Relationship Between Smes, Nader Ale Ebrahim, Shamsuddin Ahmed, Zahari Taha

Nader Ale Ebrahim

This paper explores potential advantages and barriers of virtual teams toward making an interrelation between small and medium-sized firms (SMEs) with a comprehensive review on different aspects of virtual teams in SMEs based on authentic and reputed publications. The purpose of the state-of-the-art literature review is to provide an overview of what is known about the structure and dynamics of virtual collaboration in SMEs which they are the back bone of the world business. This study seeks to address some of the advantages of virtual R&D team in the existing extensive literature on the increase SMEs interrelations. Besides of identify …

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On The Analytical And Numerical Solutions Of Discretized Constrained Optimal Control Problem, Adeshina I. Adekunle Dec 2009

On The Analytical And Numerical Solutions Of Discretized Constrained Optimal Control Problem, Adeshina I. Adekunle

Adeshina I. Adekunle MR

The analytical and numerical solutions of continuous linear quadratic optimal control problem are presented. Numerical solutions are obtained by shooting method and the conjugate gradient method(CGM) via quadratic programming of the discretized continuous optimal control problem. Our results show that both analytical and numerical solutions agree favourably.

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Manifest Greatness Version3 By Marc Guerrero With Jay Fajardo, Emmanuel Mario B. Santos Aka Marc Guerrero Dec 2009

Manifest Greatness Version3 By Marc Guerrero With Jay Fajardo, Emmanuel Mario B. Santos Aka Marc Guerrero

Emmanuel Mario B Santos aka Marc Guerrero

MANIFEST GREATNESS version3 by Marc Guerrero with Jay Fajardo

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Manifest Greatness Version2 With Danielle Van Asch-Prevot, Emmanuel Mario B. Santos Aka Marc Guerrero Dec 2009

Manifest Greatness Version2 With Danielle Van Asch-Prevot, Emmanuel Mario B. Santos Aka Marc Guerrero

Emmanuel Mario B Santos aka Marc Guerrero

MANIFEST GREATNESS version2 by Marc Guerrero with Danielle van Asch-Prevot

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Decision-Based Data Fusion Of Complementary Features For The Early Diagnosis Of Alzheimer's Disease, Metin Ahiskali Dec 2009

Decision-Based Data Fusion Of Complementary Features For The Early Diagnosis Of Alzheimer's Disease, Metin Ahiskali

Theses and Dissertations

As the average life expectancy increases, particularly in developing countries, the prevalence of Alzheimer's disease (AD), which is the most common form of dementia worldwide, has increased dramatically. As there is no cure to stop or reverse the effects of AD, the early diagnosis and detection is of utmost concern. Recent pharmacological advances have shown the ability to slow the progression of AD; however, the efficacy of these treatments is dependent on the ability to detect the disease at the earliest stage possible. Many patients are limited to small community clinics, by geographic and/or financial constraints. Making diagnosis possible at …

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Investigation Of The Mechanical Properties Of Poly (Ethylene Glycol) Diacrylate By Nanoindentation Using Atomic Force Microscopy, Zouheir Drira Dec 2009

Investigation Of The Mechanical Properties Of Poly (Ethylene Glycol) Diacrylate By Nanoindentation Using Atomic Force Microscopy, Zouheir Drira

Theses and Dissertations

Poly (ethylene glycol) (PEG) hydrogel based polymers are among the most widely used synthetic materials for biomedical applications. Because of their biocompatibility, and ease of fabrication, hydrogels are highly suitable for use as constructs to engineer tissues as well as for cell transplantation. A critical parameter of importance for PEG hydrogels is their mechanical properties which are highly dependent on the environmental conditions. Properties of PEG-based hydrogels can be engineered to resemble scaffolds composed of extracellular matrix molecules, which provide structural support, adhesive sites and mechanical as well as biomechanical signals to most cells. The mechanical properties of these synthetic …

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Polar Fuzzy Logic Based Power System Stabilizer, D. K. Chaturvedi Dec 2009

Polar Fuzzy Logic Based Power System Stabilizer, D. K. Chaturvedi

D. K. Chaturvedi Dr.

A neuro fuzzy logic based adaptive power system stabilizer (AFPSS) has been developed using angularspeed deviation and angular acceleration as the input variables. It consists of two main parts, namely, fuzzylogic controller (FLC) and generalized neuron (GN) based identifier. The inference mechanism of the fuzzylogic controller is represented by rule-base and a data-base. Three parameters have been introduced to tunethe FPSS. These parameters are decided on the basis of GN-identifier output and present system conditions.This mechanism of tuning the AFPSS makes the fuzzy logic based power system stabilizer adaptive tochanges with the operating conditions. Therefore, the degradation of the system …

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Analyzing Systems Integration Best Practices And Assessment In Dod Space Systems Acquisition, Douglas R. Dillon, Enriqueta M. Styres Dec 2009

Analyzing Systems Integration Best Practices And Assessment In Dod Space Systems Acquisition, Douglas R. Dillon, Enriqueta M. Styres

Theses and Dissertations

Senior leadership of the Air Force's Space and Missile Center suggested an investigation of systems integration within the space acquisition community in the fall of 2008. This thesis performs that investigation. A review concluded that while Systems Integration (SI) is extensively discussed as an area deserving considerable attention in the Systems Engineering literature, definitions are weak and methods and tools non-existent. Known SI activities are not being traced and assessed for adequacy throughout system development. Employing the Space System Acquisition Lifecycle Framework as the environment for this research, a method of characterizing and tracing SI throughout a program‘s lifecycle by …

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Extending The Strategy Based Risk Model Using The Delphi Method: An Application To The Validation Process For Research And Developmental (R&D) Satellites, Amanda J. Langenbrunner, Mary R. Trautwein Dec 2009

Extending The Strategy Based Risk Model Using The Delphi Method: An Application To The Validation Process For Research And Developmental (R&D) Satellites, Amanda J. Langenbrunner, Mary R. Trautwein

Theses and Dissertations

The validation between a research and developmental satellite and its ground system is critical to ensuring the success on-orbit. However, the exact process for completing validation is not documented, frequently underfunded, and accomplished ad hoc. This leads to debate regarding maintenance of budget and schedule, while ensuring on-orbit success. This thesis examines readiness and on-orbit activities within the U.S. Air Force Space Development and Test Wing's Research Development Test and Evaluation Support Complex. Combining historical data with the consultation of subject matter experts, a validation process was defined. Risks associated with this process were then analyzed using the Strategy Based …

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Manifest Greatness... Panahon Ng Mga Filipino Ang 21st Century: Ang Asian Century (Ang Pagpapanumbalik Sa Likas Na Karangalan Ng Lahat Ng Filipino Sa Buong Mundo), Emmanuel Mario B. Santos Aka Marc Guerrero Dec 2009

Manifest Greatness... Panahon Ng Mga Filipino Ang 21st Century: Ang Asian Century (Ang Pagpapanumbalik Sa Likas Na Karangalan Ng Lahat Ng Filipino Sa Buong Mundo), Emmanuel Mario B. Santos Aka Marc Guerrero

Emmanuel Mario B Santos aka Marc Guerrero

MANIFEST GREATNESS Panahon ng mga Filipino ang 21st century: Ang Asian Century (Ang pagpapanumbalik sa likas na Karangalan ng lahat ng Filipino sa buong mundo) Manifest Greatness is a work-in-progress Manifesto of, for and by Filipino citizens of the world in synergy with foreign national friends of the Filipino people worldwide in pursuit of genuine entrepreneurial wisdom

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Flow Measurements Using Particle Image Velocimetry In The Ultra Compact Combustor, Levi M. Thomas Dec 2009

Flow Measurements Using Particle Image Velocimetry In The Ultra Compact Combustor, Levi M. Thomas

Theses and Dissertations

Velocity measurements were performed using the Particle Image Velocimetry (PIV) technique on the Ultra Compact Combustor (UCC) test rig at the Air Force Institute of Technology (AFIT). Velocity patterns and time-averaged turbulence statistics were calculated for data taken with the UCC burning hydrogen fuel in the straight cavity vane and curved cavity vane configurations. The equivalence ratio was varied from 0.7 to 1.5, while the ratio of cavity air to main air was varied from 5% to 20% in testing performed on the straight vane configuration. Spanwise velocity was observed to decrease linearly with distance from the cavity vane over …

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Heat And Current Propagation In Buffered Superconducting And Hyper-Conducting Wire, Jesse L. Lynn Dec 2009

Heat And Current Propagation In Buffered Superconducting And Hyper-Conducting Wire, Jesse L. Lynn

Theses and Dissertations

This research models and analyzes the distribution of heat and current in a buffered superconducting or hyper-conducting wire that shows potential for use in different capacities in multiple Air Force systems including the Active Denial System. The thesis includes a brief background of the reaction-diffusion system of partial differential equations provided by AFRL/RZPG and development of the numerical scheme. It then explores solutions to the model. These solutions indicate some of the various heat-related failures that may be observed in such a wire. The nature of the solutions observed depends on the characteristics of the wire, operating temperature and efficiency …

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