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Articles 301 - 330 of 372
Full-Text Articles in Engineering
The Synthesis And Characterization Of Novel Elastin-Like Polypeptides Containing An Oligomerization Domain, James T. Cole
The Synthesis And Characterization Of Novel Elastin-Like Polypeptides Containing An Oligomerization Domain, James T. Cole
ETD Archive
Elastin like polypeptides (ELPs) are an emerging class of biomaterials due to their unique group of chemical, physical and biological properties. We have constructed a library of ELPs based on the pentapeptide amino acid repeat sequence (GVGVP). ELPs exhibit lower critical solution temperature (LCST) transition behavior from a soluble phase below the transition temperature (Tt) to an insoluble two phase system above the transition temperature. This process is completely reversible so that ELPs can become soluble again upon lowering the temperature. This temperature can be tuned in many different ways at the molecular level by changing the composition of the …
Investigation Of Generalized Dsss Under Multiple Access And Multipath, Indrasena Varakantham
Investigation Of Generalized Dsss Under Multiple Access And Multipath, Indrasena Varakantham
ETD Archive
In this thesis we investigate and compare the average performances of ordinary and generalized direct sequence spread spectrum (DSSS) systems under multi-path fading and multiple-access interference. As part of multiple access performance, we also consider generation of orthogonal and semi-orthogonal codes using various algorithms, and compare cross correlation properties of codes formed by 2-level and 3-level signature sequences. In order to simulate ordinary and generalized DSSS performance under various scenarios, we develop a complete Java library with classes that are well encapsulated with regard to communication modules and loosely coupled so that we can reuse them to create any type …
Effect Of Rib Turbulators On Heat Transfer Performance In Stationary Ribbed Channels, Aravind Rohan Sampath
Effect Of Rib Turbulators On Heat Transfer Performance In Stationary Ribbed Channels, Aravind Rohan Sampath
ETD Archive
The thermal performance was examined computationally for the stationary channels with rib turbulators oriented at 90 degrees. Ribs were placed on opposite walls and the heat transfer coefficients and frictional loss were calculated. Three stationary channels with aspect ratios (W/H) 1, 2 and 4 were considered for the analysis. The thermal performance was measured by calculating the Nusselt number and frictional losses. Square ribs (w/e = 1) were considered as the baseline configuration. The rib width and rib spacing varies while the rib height is maintained constant. Rib spacing (P/e) of 10 and 20 and rib width to rib height …
Biological Treatment Of Dietary Supplement Wastewater, Erick Benjamin Butler
Biological Treatment Of Dietary Supplement Wastewater, Erick Benjamin Butler
ETD Archive
Dietary supplement wastewater contains higher order polysaccharides such as the complex sugars maltodextrin and low fat milk. These complex sugars contain a significant amount of organic carbon therefore, presence of these sugars can pose threats to the environment if discharged without treatment. While many food processing plants are required to send their waste through wastewater treatment, legislation may require preliminary treatment of these wastes in order to satisfy the effluent discharge requirements. Because of the high organic carbon presence, it would be preferable to use biological treatment methods to reduce the organics present within the system. Microorganisms are capable of …
Wind Flow Induced Vibrations Of Tapered Masts, Ahmad Bani-Hani
Wind Flow Induced Vibrations Of Tapered Masts, Ahmad Bani-Hani
ETD Archive
Structural dynamic analyses of elongated masts subjected to various wind speeds are presented in this work. The masts are modeled as vertically supported cantilever beams,with one end fixed to the ground, and the other end free. The external excitation forces acting of the masts are the results of vortex shedding represented by a sinusoidal time dependent functions. The frequencies of these sinusoidal functions are dictated by the Strouhal numbers associated of the flow regimes crossing over the masts. To enhance the vibratory behavior of a typical mast, under the influence of flow induced vibrations,three different mass distributions along the length …
Dynamic Analysis Of A Rotor Bearing System, Sandi Elhibir
Dynamic Analysis Of A Rotor Bearing System, Sandi Elhibir
ETD Archive
This thesis presents the results of the finite element analysis (FEA) approach for designing a Permanent Magnet Alternator (PMA). The PMA is configured as a cantilever hollow shaft supported by two identical rolling contact bearings. The performance requirements of the PMA are a maximum operating speed of 16,000 rpm, with a maximum shaft displacement of less than 0.010 in at its free end. The static and dynamic results of a cantilever beam was predicted by closed form solutions and verified to those results obtained from FEA for code validation. A mathematical model of a rotor-bearing system was proposed and analyzed …
Non-Collocation Problems In Dynamics And Control Of Mechanical Systems, Timothy M. Obrzut
Non-Collocation Problems In Dynamics And Control Of Mechanical Systems, Timothy M. Obrzut
ETD Archive
Characteristics of mechanical systems with non-collocated sensors and actuators are investigated. Transfer function zeros location as a function of sensor position, zero-pole interlacing, and re-location of zeros are discussed in a context of presented examples. Some of the presented examples involving non-collocation are supported by experimental data. A case study involving a high speed machining spindle is examined. The control problems associated with non-collocation are studied along with the methods to solve them
Smart Rotating Machines For Structural Health Monitoring, Dmitry Leonidovich Storozhev
Smart Rotating Machines For Structural Health Monitoring, Dmitry Leonidovich Storozhev
ETD Archive
The objective of this thesis is to explore an innovative approach to the on-line health monitoring of rotating machinery in the presence of structural damage using active magnetic bearings (AMBs). First, the detailed model of the rotor with the breathing transverse crack is developed using finite element method. Next, the experimental data from the rotating magnetically levitated healthy and cracked shafts, under specially designed external excitation force, was collected, analyzed and compared with the computer simulation. The obtained results demonstrate that the presented on-line health monitoring technique is very effective for detection of the structural damage in rotating machinery, and …
Slurry Based Coatings On Silicon Based Ceramics, Muralidhar Challarapu
Slurry Based Coatings On Silicon Based Ceramics, Muralidhar Challarapu
ETD Archive
Silicon carbide/silicon carbide (SiC/SiC) composites are the leading candidates for advanced high temperature structural components in gas turbine engine application. When SiC surface reacts with O2, protective SiO2 scales are formed, which are the basis for the corrosion resistance of SiC. Their main draw back in terms of usage in a gas-turbine engine is the volatilization of the protective silica scale because of the water vapor which is a byproduct of fuel combustion. The purpose of this project was to develop environmental barrier coatings (EBCs) based on ceramic powders to provide resistance to such moisture damage. In this thesis slurry-coating …
Experimental Study Of Multirate Margin In Software Defined Multirate Radio, Tianning Shen
Experimental Study Of Multirate Margin In Software Defined Multirate Radio, Tianning Shen
ETD Archive
Due to the recent development of spectrally-efficient modulation schemes, IEEE 802.11 Wifi and IEEE 802.16 WiMax radios support wireless communication at multiple bit rates. While high-rate transmission allows delivering more information in less time, the corresponding performance improvement is less than expected due to the PHY- and MAC-layer overheads, imposed by the 802.11/16 standards. This is particularly true in wireless ad hoc networks as there exist rate-distance and rate-hop count tradeoffs. The concept of multi-rate margin is proposed in this thesis, which exploits the difference in communication characteristics at different rates and serves as the fundamental ingredient for an opportunistic …
Multihop Transmission Opportunistic Protocol On Software Radio, Sachin C. Hirve
Multihop Transmission Opportunistic Protocol On Software Radio, Sachin C. Hirve
ETD Archive
The need of high speed communication motivates us to use high bit rate communication to transmit more information in as little time as possible. However, MAC layer protocol overheads dominate the transmission capability particularly at high rates and hinder high speed transmission. Opportunistic transmission has been proposed to help to overcome this disadvantage by transmitting packets back-to-back without inter-packet delays. Though this approach alleviates the problem in single-hop wireless LAN scenario, it doesn't help in multi-hop networks. This thesis presents an approach for multi-hop wireless networks, which is named as Multi-hop Transmission OPportunity (MTOP). It achieves better performance by ensuring …
Performance Engineering Of A Lightweight Fault Tolerance Framework, Hua Chai
Performance Engineering Of A Lightweight Fault Tolerance Framework, Hua Chai
ETD Archive
It is well-known that the Paxos algorithm can be used to build provably correct practical fault tolerant systems. In this thesis, a lightweight consensus framework - Paxos-Based Fault Tolerance (PFT) framework and its practical implementation is presented. It also includes how the system tolerates faults under practical conditions where the replicas might not be strictly homogeneous due to the asynchrony of their deployment environment. A comprehensive performance evaluation study is performed on the PFT framework. The approaches that can optimize the fault tolerance mechanisms under various practical scenarios are also discussed
On Traffic Analysis Attacks To Encrypted Voip Calls, Yuanchao Lu
On Traffic Analysis Attacks To Encrypted Voip Calls, Yuanchao Lu
ETD Archive
The increasing popularity of VoIP telephony has brought a lot of attention and concern over security and privacy issues of VoIP communication. This thesis proposes a new class of traffic analysis attacks to encrypted VoIP calls. The goal of these attacks is to detect speaker or speech of encrypted VoIP calls. The proposed traffic analysis attacks exploit silent suppression, an essential feature of VoIP telephony. These attacks are based on application-level features so that the attacks can detect the same speech or the same speaker of different VoIP calls made with different VoIP codecs. We evaluate the proposed attacks by …
Tracking In Wireless Sensor Network Using Blind Source Separation Algorithms, Anil Babu Vikram
Tracking In Wireless Sensor Network Using Blind Source Separation Algorithms, Anil Babu Vikram
ETD Archive
This thesis describes an approach to track multiple targets using wireless sensor networks. In most of previously proposed approaches, tracking algorithms have access to the signal from individual target for tracking by assuming (a) there is only one target in a field, (b) signals from different targets can be differentiated, or (c) interference caused by signals from other targets is negligible because of attenuation. We propose a general tracking approach based on blind source separation, a statistical signal processing technique widely used to recover individual signals from mixtures of signals. By applying blind source separation algorithms to mixture signals collected …
Structural And Thermal Analysis Of Hose For Lng Applications, Bipin G. Kashid
Structural And Thermal Analysis Of Hose For Lng Applications, Bipin G. Kashid
ETD Archive
Finite element analysis (FEA) of the hose assembly used for transportation of Liquefied natural gas (LNG) has become a powerful tool in predicting the deformation and stress distributions. FEA helps in analyzing the model and optimizing the design in hostile environment. In the present work, computations are made to predict the maximum stresses caused due to structural and thermal effects in the LNG transportation. The analysis leads to the selection of the appropriate materials to be used and to the identification of both the most critical measurements and parameters. Most engineering design methods are deterministic, but in reality, many engineering …
Biogeography-Based Optimization: Synergies With Evolutionary Strategies, Immigration Refusal, And Kalman Filters, Dawei Du
ETD Archive
Biogeography-based optimization (BBO) is a recently developed heuristic algorithm which has shown impressive performance on many well known benchmarks. The aim of this thesis is to modify BBO in different ways. First, in order to improve BBO, this thesis incorporates distinctive techniques from other successful heuristic algorithms into BBO. The techniques from evolutionary strategy (ES) are used for BBO modification. Second, the traveling salesman problem (TSP) is a widely used benchmark in heuristic algorithms, and it is considered as a standard benchmark in heuristic computations. Therefore the main task in this part of the thesis is to modify BBO to …
Rotor Position And Vibration Control For Aerospace Flywheel Energy Storage Devices And Other Vibration Based Devices, B. X. S. Alexander
Rotor Position And Vibration Control For Aerospace Flywheel Energy Storage Devices And Other Vibration Based Devices, B. X. S. Alexander
ETD Archive
Flywheel energy storage has distinct advantages over conventional energy storage methods such as electrochemical batteries. Because the energy density of a flywheel rotor increases quadratically with its speed, the foremost goal in flywheel design is to achieve sustainable high speeds of the rotor. Many issues exist with the flywheel rotor operation at high and varying speeds. A prominent problem is synchronous rotor vibration, which can drastically limit the sustainable rotor speed. In a set of projects, the novel Active Disturbance Rejection Control (ADRC) is applied to various problems of flywheel rotor operation. These applications include rotor levitation, steady state rotation …
Characterization Of Changes In Hyaluronan Following Epidermal Barrier Injury In An Organotypic Model, Gati Ajani
Characterization Of Changes In Hyaluronan Following Epidermal Barrier Injury In An Organotypic Model, Gati Ajani
ETD Archive
The stratum corneum, the outermost layer of the epidermis of skin, provides a functional permeability barrier that is essential for our survival and must be rapidly repaired after injury. Of interest to us, a ubiquitous matrix molecule called hyaluronan (HA) has come to the forefront in wound healing research because it is induced after epidermal injury and may be crucial for barrier repair. This thesis examines the role of HA during recovery from the most fundamental form of skin injury, i.e. selective damage to the stratum corneum. The overall question is whether this form of stratum corneum injury can lead …
Novel Antifreeze Protein Constructs For Improved Activity, Ozge Can
Novel Antifreeze Protein Constructs For Improved Activity, Ozge Can
ETD Archive
Many organisms are exposed to subzero temperatures in nature and can survive these temperatures by the effect of antifreeze proteins (AFPs), which inhibit ice crystal growth and change the morphology of ice crystals. Although the effects of these proteins, such as recrystallization inhibition, ice growth inhibition, and crystal habit changes, are known, a conclusive description of the protein-ice crystal interaction including interaction energy, surface coverage, and lifetime of adsorbate has been elusive. In this study, different antifreeze protein constructs are designed and expressed such that they can be conjugated to polymers to increase the thermal hysteresis activity especially at low …
Fabrication Of Nanostructured Metals And Their Hydrogen Storage Properties, Asli Ertan
Fabrication Of Nanostructured Metals And Their Hydrogen Storage Properties, Asli Ertan
ETD Archive
Searching for new energy sources is highly desirable for the next generations when rapidly changing factors are considered such as population, increasing pollution and exhaustion of fossil fuels. Hence, there is a need for clean, safe and efficient energy carriers or forms of energy that can be transported to the end user. One of these energy carriers is electricity which has been used widely and can be produced from various sources. However, its production from fossil fuels contributes to pollution. On the other hand hydrogen, due to its abundance, light weight, low mass density, high energy density and non-polluting nature …
A Hybrid Reconfigurable Solar And Wind Energy System, Sagar A. Gadkari
A Hybrid Reconfigurable Solar And Wind Energy System, Sagar A. Gadkari
ETD Archive
We study the feasibility of a novel hybrid solar-wind hybrid system that shares most of its infrastructure and components. During periods of clear sunny days the system will generate electricity from the sun using a parabolic concentrator. The concentrator is formed by individual mirror elements and focuses the light onto high intensity vertical multi-junction (VMJ) cells. During periods of high wind speeds and at night, the same concentrator setup will be reconfigured to channel the wind into a wind turbine which will be used to harness wind energy. In this study we report on the feasibility of this type of …
The Development Of An In Vivo Spinal Fusion Monitor Using Microelectromechanical (Mems) Technology To Create Implantable Microsensors, Lisa Anne Ferrara
The Development Of An In Vivo Spinal Fusion Monitor Using Microelectromechanical (Mems) Technology To Create Implantable Microsensors, Lisa Anne Ferrara
ETD Archive
Surgical fusion of the spine is a conventional approach, and often last alternative, to the correction of a degenerative painful spinal segment. The procedure involves the surgical removal of the intervertebral disc at the problematic site, and the placement of a bone graft that is commonly harvested from the patients iliac crest and placed within the discectomized space. The surrounding bone is expected to incorporate and remodel into the bone graft to eventually provide an immobilized site. Spinal instrumentation often accompanies the bone graft to provide further immobility to the targeted site, thus augmenting the fusion process. However, the status …
Effective Area And Effective Volume Calculations For Ceramic Test Specimens, Rahul Jain
Effective Area And Effective Volume Calculations For Ceramic Test Specimens, Rahul Jain
ETD Archive
Calculation of effective volume and/or effective area is a key step in estimating reliability of ceramic component life cycle. Most common tests performed to assess the strength and reliability of components made from ceramics are bend bar specimens tested in three-point and four-point flexure, C-ring and O-ring specimen under diametral compressive or tensile loads and biaxial ring-on-ring specimens. ASTM closed form solutions for the effective volume and area exists for these specimen geometries which are based on classical theories with underlying assumptions. In general the closed form expressions are valid for limited specimen geometry bounds. An alternative numerical approach has …
Relationship Between Arch Height And Midfoot Joint Pressures During Gait, Dong Gil Lee
Relationship Between Arch Height And Midfoot Joint Pressures During Gait, Dong Gil Lee
ETD Archive
A foot arch is a multi-segmented curved structure which acts as a spring during locomotion. It is well known that ligaments are important components contributing to this spring-like property of the arch. In addition, intrinsic and extrinsic foot muscles contribute to arch support. According to the windlass foot model, arch height and midfoot joint orientation change during gait. However, it is not known whether altered joint configurations result in increased joint stress during gait. If so, it is possible for there to be a "vicious cycle" in which joint stress increases as the arch height diminishes, which may then lead …
Greenometer-7: A Tool To Assess The Sustainability Of A Building's Life Cylce At The Conceptual Design Phase, Muhammad Musa Mer'eb
Greenometer-7: A Tool To Assess The Sustainability Of A Building's Life Cylce At The Conceptual Design Phase, Muhammad Musa Mer'eb
ETD Archive
This study presents a tool that has been developed to measure and subsequently improve the sustainability performance of a building over its entire life-cycle while still at the conceptual design stage. This forecasting tool is called GREENOMETER-7. GREENOMETER-7 is a LCA tool and it evaluates the projected building at two levels: micro- and macro-assessment. The micro-assessment level provides in-depth analysis of the building products, components, and operations however, the macro-assessment level measures the sustainability performance of the building as a whole and covers areas that are not applicable at the product or component level. Both levels consist of categories and …
Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms For Magnetic Cell Separation, Pulak Nath
Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms For Magnetic Cell Separation, Pulak Nath
ETD Archive
Microfluidic platforms for magnetic cell separation were developed and investigated for isolation of magnetic particles and magnetically tagged cells from a fluidic sample. Two types of magnetic separation platforms were considered: an Isodynamic Open Gradient Magnetic Sorter (OGMS) and a multistage bio-ferrograph. Miniaturized magnets were designed using magnetostatic simulation software, microfluidic channels were fabricated using microfabrication technology and magnetic separation was investigated using video microscopy and digital image processing. The isodynamic OGMS consisted of an external magnetic circuit and a microfabricated channel (biochip) with embedded magnetic elements. The biochip is placed inside the magnetic field of the external circuit to …
A Novel Cardiac Pacing Paradigm For Atrial Fibrillation And Heart Failure Patients, George Emanuel Yanulis
A Novel Cardiac Pacing Paradigm For Atrial Fibrillation And Heart Failure Patients, George Emanuel Yanulis
ETD Archive
It has been estimated that 4.6 million persons have heart failure, and 400,000 to 700,000 new cases develop each year and the U.S. Hospital discharges for HF rose from 399,000 in 1979 to 1,099,000 in 2004 according to the National Hospital Discharge Survey. Atrial fibrillation is the most common sustained cardiac arrhythmia in the United States. Recent studies have demonstrated that ventricular rate control is a viable treatment strategy for patients in atrial fibrillation. In a number of cases, despite the electrical resynchronization of the ventricles using biventricular pacing (cardiac resynchronization therapy), heart failure patients in sinus rhythm do not …
Bio-Signal Analysis In Fatigue And Cancer Related Fatigue;Weakening Of Corticomuscular Functional Coupling, Qi Yang
ETD Archive
Fatigue is a common experience that reduces productivity and increases chance of injury, and has been reported as one of most common symptoms with greatest impact on quality-of-life parameters in cancer patients. Neural mechanisms behind fatigue and cancer related fatigue (CRF) are not well known. Recent research has shown dissociation between changes in brain and muscle signals during voluntary muscle fatigue, which may suggest weakening of functional corticomuscular coupling (fCMC). However, this weakening of brain-muscle coupling has never been directly evaluated. More important information could be gained if fCMC is directly detected during fatigue because a voluntary muscle contraction depends …
Biocompatibility Of Osteoblast Cells On Titanium Implants, Dilip Ayyala Somayajula
Biocompatibility Of Osteoblast Cells On Titanium Implants, Dilip Ayyala Somayajula
ETD Archive
Adhesion and proliferation of UMR 106-01 osteoblast cells were studied on various surface modified titanium materials such as polished, sandblasted, anodized and alkaline treated. Anodization of polished surface in Hydrofluoric acid developed nano-tubes, while NaOH treatment produced spongy microporous morphology. Test samples were coated with non-adhesive protein bovine serum albumin and compared with fibronectin coated specimens. The adhesion study lasted for 4 hrs, where osteoblast cells were cultured in serum free medium. Polished titanium, anodized titanium and NaOH titanium have shown similar percentages of cell adherence. The proliferation study lasted for 48 hrs, where cells were initially allowed to adhere …
Broader Use Of Steel Slag Aggregates In Concrete, Jigar P. Patel
Broader Use Of Steel Slag Aggregates In Concrete, Jigar P. Patel
ETD Archive
Steel slag is an industrial byproduct obtained from the steel manufacturing industry. It is produced in large quantities during the steel-making operations which utilize Electric Arc Furnaces (EAF). Steel slag can also be produced by smelting iron ore in the Basic Oxygen Furnace (BOF). Steel slag can be used in the construction industry as aggregates in concrete by replacing natural aggregates. Natural aggregates are becoming increasingly scarce and their production and shipment is becoming more difficult. Steel slag is currently used as aggregate in hot mix asphalt surface applications, but there is a need for some additional work to determine …