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Full-Text Articles in Engineering
Stress Distribution And Strength Prediction Of Composite Laminates With Multiple Holes, Brian Esp
Stress Distribution And Strength Prediction Of Composite Laminates With Multiple Holes, Brian Esp
Mechanical and Aerospace Engineering Dissertations
The major purpose of this study was to investigate failure of composite laminates with multiple unloaded holes in close proximity. The least square boundary collocation method for anisotropic materials was utilized to determine the state of stress. The approach utilized collocation on both the internal and external boundaries, making it relatively easy to implement. The method compared favorably to both published and finite element solutions. A failure prediction approach for an infinite, symmetric and balanced laminate, with two holes in close proximity was presented. The baseline material for consideration was IM7/977-3, a carbon fiber/epoxy lamina. The failure prediction method was …
On The Near Field Mean Flow Structure Of Transverse Jets Issuing Into A Supersonic Freestream, Dean Anthony Dickmann
On The Near Field Mean Flow Structure Of Transverse Jets Issuing Into A Supersonic Freestream, Dean Anthony Dickmann
Mechanical and Aerospace Engineering Dissertations
The near field mean flow structure of transverse jets issuing from a surface into supersonic crossflow is examined using numerical methods and separation topology. The Navier-Stokes solver Falcon, developed at Lockheed Martin, was used to simulate the interaction between the jet and freestream over a flat plate and a generic missile body. The near field flow structure included a l bow shock upstream of the jet interacting with the approaching boundary layer that forms a pair of horseshoe vortices while another l- structure closer to the jet formed a second pair of horseshoe vortices. As the jet was turned downstream …
An Experimental Study On Thermal Bonding Effects Of Pmma Based Micro-Devices Using Hot Embossing, Varun Sood
An Experimental Study On Thermal Bonding Effects Of Pmma Based Micro-Devices Using Hot Embossing, Varun Sood
Mechanical and Aerospace Engineering Theses
Basic configuration and functioning of various subsystems of a developed HEMM system for thermal bonding are discussed. The bond strength and micro channel geometry degradations dependence on controlled process parameters in thermal bonding using hot embossing has been investigated. The process parameters examined were bonding temperature, bonding or applied load and holding time. Polymeric substrates with different feature dimensions and thickness were embossed and bonded using hot embossing technology. The feature dimensions before and after bonding were examined to assess the geometry changes as functions of the bonding process. This assessment could provide guidance during the design phase of micro-fluidic …
Derivation Of The Dynamics Equations For Receiver Aircraft In Aerial Refueling, Jayme Lynn Waishek
Derivation Of The Dynamics Equations For Receiver Aircraft In Aerial Refueling, Jayme Lynn Waishek
Mechanical and Aerospace Engineering Theses
This thesis describes the derivation of a new set of nonlinear, 6--DOF equations of motion of a receiver aircraft undergoing an aerial refueling, including the effect of time-varying mass and inertia properties associated with the fuel transfer and the tanker's vortex induced wind effect. Since the center of mass of the receiver is time--varying during the fuel transfer, the equations are written in a reference frame that is geometrically fixed in the aircraft. Due to the fact that aerial refueling simulation and control deal with the position and orientation of the receiver relative to the tanker, the equations of motion …
Modeling Unsaturated Soil Response Under Suction-Controlled Multi-Axial Stress States, Arthit Laikram
Modeling Unsaturated Soil Response Under Suction-Controlled Multi-Axial Stress States, Arthit Laikram
Civil Engineering Dissertations
In this research work, a novel suction-controlled true triaxial testing apparatus has been developed to test 3-in (7.5-cm) side, cubical specimens of unsaturated soil under controlled-suction states for a wide range of stress paths that are not easily achievable in a conventional cylindrical apparatus. The equipment is a mixed-boundary type of device, with the specimen seated on top of a high-air-entry ceramic disk and between five flexible (latex) membranes on the remaining sides of the cube. The new cell is an upgraded, more elaborate version of the one previously reported by Hoyos (1998), featuring two independent pore-air and pore-water pressure …
Deep Mixing Technology For Mitigation Of Swell-Shrink Behavior Of Expansive Soils Of Moderate To Deep Active Depths, Raja Sekhar Madhyannapu
Deep Mixing Technology For Mitigation Of Swell-Shrink Behavior Of Expansive Soils Of Moderate To Deep Active Depths, Raja Sekhar Madhyannapu
Civil Engineering Dissertations
Expansive soils are well known for their cyclic shrink-swell behavior due to seasonal related moisture changes. These cyclic movements of expansive soils are due to physico-chemical changes at particle level that are dependent on mineralogical composition of these soils. The subsoil depths susceptible to moisture changes are known as active zones and based on previous studies vary from shallow to deep depths. Movements from these active depths reflect to the surface and cause considerable damages to overlying infrastructures. These damages are slow and time dependent as the in situ moisture fluctuations are slow and continue with time. Since the current …
Methodologies For Automated Microassembly, Mohammad A. Mayyas
Methodologies For Automated Microassembly, Mohammad A. Mayyas
Mechanical and Aerospace Engineering Dissertations
The development of micromachining technologies has provided wide applications in micro sensing and actuation. However, most of the demonstrated devices are selectively constructed by fabrication processes that are limited to complexity, configuration, dimension, and material variation. The monolithic fabrication has limitations and does not allow the inclusion of multiple components of incompatible processes. Therefore, the construction of 3D microstructures by heterogeneous microassembly is an alternate manufacturing route. In deterministic, monitored or controlled microassembly there has been considerable research in developing, analyzing and applying distributed algorithms for sensor and sensorless based assembly processes. Meso-scale teleoperated work-cells supported by Nano manipulators have …
An Analytical And Numerical Model For Design Of Non- Uniformly Powered Silicon Chips Based On Both Thermal And Device Clock Performance, Abhihit D. Kaisare
An Analytical And Numerical Model For Design Of Non- Uniformly Powered Silicon Chips Based On Both Thermal And Device Clock Performance, Abhihit D. Kaisare
Mechanical and Aerospace Engineering Dissertations
Silicon chips continue to grow in capabilities, complexity and performance. Silicon chips typically integrate functional components such as logic and level two (L2) cache memory in their architecture. This functional integration of logic and memory results in improved performance of the chip. However, the integration also introduces a layer of complexity in the thermal design and management of silicon chips. As a direct result of functional integration, the power map on a silicon chip is typically highly non-uniform and the assumption of a uniform heat flux across the chip surface has been shown to be invalid post Pentium II architecture. …
Formulation Of Lean Six Sigma Critical Business Processes For Manufacturing Facilitites, Chaucey Chandler
Formulation Of Lean Six Sigma Critical Business Processes For Manufacturing Facilitites, Chaucey Chandler
Industrial, Manufacturing, and Systems Engineering Dissertations
The author desired to create a method organizing the concepts from Lean, Six Sigma, critical business processes, and simplifying the usage of these concepts to identify Lean Six Sigma Critical Business Processes. Inspired by Laura Meade (1997) and the author's passion concerning process improvements, this research was created. Lean activities eliminate waste, Six Sigma activities eliminate variation, critical business processes focus on those areas that need improvement and are critical to the process, and Analytical Network Process (ANP) models problems considering the interactions between levels. There is value for all companies to implement at least one of these tools. Since …
On The Study Of Multi-Channel Eeg: Lossless Compression, Signal Modeling And Classification, Yodchanan Wongsawat
On The Study Of Multi-Channel Eeg: Lossless Compression, Signal Modeling And Classification, Yodchanan Wongsawat
Electrical Engineering Dissertations
Recently, electroencephalogram (EEG) has become necessary for diagnosis, telemedicine, and brain computer interface (BCI). This thesis investigates three signal processing tools which can explore multi-channel structures of the EEG for different applications such as lossless compression, artifact removal, and classification. First, this thesis presents a method for approximating the Karhunen-Loeve transform (KLT) of multi-channel EEG signals. The proposed transform is further parameterized by lifting factorization by which the coefficients' dynamic range is controlled through a proposed pivoting scheme, rendering a reversible structure under quantization of coefficients called IntSKLT. A lossless coder for multi-channel EEG signals which exploits inter-channel correlation among …
Surface Patterning Of Biodegradable Polymer In Tissue Engineering By Applying Photolithography, Lee-Chun Su
Surface Patterning Of Biodegradable Polymer In Tissue Engineering By Applying Photolithography, Lee-Chun Su
Material Science and Engineering Theses
The prevalence of cardiovascular disease and inherent problems with current surgical therapies has prompted major efforts in the field of vascular tissue engineering. While there have been significant advances towards creating functional blood vessel substitutes, the fabrication of a vascular graft with mechanical, structural and functional properties similar to native vessels has not yet been achieved. We have presented an observation of a new biodegradable polymer utilized on the research of tissue engineering. Our idea was to create a structure to imitate blood vessel muscles in vitro and also to guide the cells when they start spreading and trying to …
Synthesis, Structure And Characterization Of Silver Doped Diamond Like Carbon Thin Films, Pankaj Jyoti Hazarika
Synthesis, Structure And Characterization Of Silver Doped Diamond Like Carbon Thin Films, Pankaj Jyoti Hazarika
Material Science and Engineering Theses
Diamond like carbon (DLC) films have gained grounds in the biomedical field as an inert, biocompatible, low friction and wear resistant coating and are widely used in heart valves, coronary artery stents, dental implants, knee prosthesis and other vascular devices. In addition, Ag nanoparticles/films can prevent the formation of biofilm on biomedical implants by degrading the metabolic activities like permeability and respiration and also impair DNA replicability. Thus, Ag-doped DLC (Ag-DLC) can serve as a multifunctional bio coating combining desirable antibacterial and physical/ mechanical characteristics. In the present study, Ag-DLC films were synthesized utilizing a hybrid Plasma CVD and Magnetron …
Synthesis And Characterization Of Ferromagnetic Nanoparticles, Kazuaki Yano
Synthesis And Characterization Of Ferromagnetic Nanoparticles, Kazuaki Yano
Material Science and Engineering Theses
Ferromagnetic nanoparticles and their bimagnetic nanoparticles with uniform size distribution have drawn great attention in the past decades because of their unique magnetic properties and potential applications in high density recording media, exchange-spring permanent magnets and biotechnology. In this thesis, synthesis and characterization of ferromagnetic nanoparticles (FePt, Sm-Co system) and bimagnetic nanoparticles (FePt/Fe3O4, FePt/Au) are reported. FePt nanoparticles with different sizes and compositions were successfully synthesized via chemical synthesis. FePt particle size was tuned to a range of from 3 nm to 8 nm with 1 nm accuracy by changing the surfactant to Pt precursor ratio. By optimizing the amount …
Thermally Activated Sulfurization Scheme For Cuins2 Solar Cells, Karan Agrawal
Thermally Activated Sulfurization Scheme For Cuins2 Solar Cells, Karan Agrawal
Material Science and Engineering Theses
Chalcopyrite Solar Cells are now being fabricated on flexible (polymer) substrates. However, CuInS2 solar cells have not been fabricated on the polymer substrates on the commercial scale due the sulfurization temperature which limits the use of polymer substrates during fabrication. To overcome this problem a thermally activated sulfurization process for the manufacture of CuInS2 solar cells from the Cu-In bilayers is described in this work. This sulfurization process can be employed for lower temperature for the formation of the absorber layer. For the sulfurization, the Cu-In bilayer with different compositions is prepared by thermal evaporation in which the In-rich film …
Sequences Of Bayes Gaussian Classifier, Jimy Shah
Sequences Of Bayes Gaussian Classifier, Jimy Shah
Electrical Engineering Theses
A new method for designing sequences of Bayes Gaussian Classifiers is presented in this thesis. First, a basic Bayes Gaussian Classifier is designed with an assumption of data being Gaussian. Then, we have used the Output Weight Optimization-Back Propagation (OWO-BP) technique to iteratively modify the coefficients of the classifier, resulting in less classification error. Through use of an iterative Gram-Schmidt procedure, to train linear functional link nets, input features are ordered from most useful to least useful. Another important development in this thesis is the generation of nested feature subsets. This ensures that the curve for error percentage versus the …
Embedded System For Monitoring Human Activities Using 3-Axis Accelerometer, Himabindu Yamana
Embedded System For Monitoring Human Activities Using 3-Axis Accelerometer, Himabindu Yamana
Electrical Engineering Theses
The last decade has witnessed a surge of interest in new sensing and monitoring devices for health care. In several medical and non-medical applications it is necessary to measure the human activities. Detection and monitoring of human activities requires the use of external sensors around the body. The reported design provides a systematic approach for characterization of states. The design employs a 3-axis accelerometer, a microcontroller and RS232 based communication protocol for sensing the activities of a person and the output will be seen on a PC with a graphical user interface. Experiments were conducted on human test subjects and …
Suppressing Delta-I Noise In Mcml Circuits In Mixed Signal Environment, Ritesh Jayant Mehta
Suppressing Delta-I Noise In Mcml Circuits In Mixed Signal Environment, Ritesh Jayant Mehta
Electrical Engineering Theses
This work addresses the problem of simultaneous switching noise (SSN) in mixed signal environment. It is shown that the Metal Oxide Semiconductor Current Mode Logic (MCML) can be used to minimize the SSN. In short channel devices, Drain Induced Barrier Lowering (DIBL) effect causes the current mismatch problem. It is seen that this current mismatch problem aggravates SSN. Basic logic gates were designed using MCML topology at 5 Gbps. Parasitic model was introduced at power supply lines and substrate to study the behaviour of these logic gates in the presence of parasitics. Interpolation type delay cells were used to suppress …
Localization In Noisy Environment Using Extended Kalman Filter, Aneeket Suresh Patkar
Localization In Noisy Environment Using Extended Kalman Filter, Aneeket Suresh Patkar
Electrical Engineering Theses
Localization is an important aspect of Wireless Sensor Networks. Information regarding the position of the sensor nodes is not always known. Without the position information of the sensors, the data reported by the sensors is of little use. Various approaches have been used to perform localization using some information about the sensor node. Potential field approach for localization, using distance information has been successfully tested with satisfactory results. However in case of noisy environment, the range measurements have greater inaccuracy. In such cases, localization using the above algorithm can provide some inaccuracy. To rectify such erroneous localization situations, Extended Kalman …
Decoupling Of Hamiltonian System With Applications To Linear Quadratic Problem, Vishal Gupta
Decoupling Of Hamiltonian System With Applications To Linear Quadratic Problem, Vishal Gupta
Electrical Engineering Theses
This thesis provides a method of decoupling the Hamiltonian system with application to linear quadratic problem in control system. Resulting decoupled Hamiltonian system helps in formulating easy closed form solution to various optimal control problems. These closed form solution are improvement over the problem of solving first order nonlinear differential equations in conventional methods. Decoupling also eliminates the constraint, "Q = 0 " for certain type of optimal control.
A Potential Field Approach For Distributed Control Of Discrete Actuator And Sensor Arrays, Pritpal S. Dang
A Potential Field Approach For Distributed Control Of Discrete Actuator And Sensor Arrays, Pritpal S. Dang
Electrical Engineering Dissertations
This dissertation presents new methods of distributed sensing, classification and actuation using potential field and neural network approaches. Human look-a-like robot serves as an excellent tool to implement the strategies developed for sensing, classification and actuation. Achieving dexterity in human-machine interaction or human look-a-like robot helps in better understanding of dynamic and complex environment. This work deals with the issues related to gain autonomy and adaptability through distributed sensing, classification and actuation capabilities. The work presented here starts by mentioning novel strategies employed for morphing a flexible structure to achieve the desired expressions on the artificial skin and then moves …
Cross-Layer Design For Wireless Ad Hoc Sensor Networks, Xinsheng Xia
Cross-Layer Design For Wireless Ad Hoc Sensor Networks, Xinsheng Xia
Electrical Engineering Dissertations
Cross-layer design is an efficient approach to enhance energy efficiency and Quality of Service (QoS) in wireless ad hoc sensor networks. This dissertation will focus on the cross-layer issues and approaches. It will also discuss the latency-aware and energy efficiency tadeoffs and the packets transmission in the rear part of the dissertation. Firstly, we will analyze the cross-layer design for wireless sensor networks based on the virtual MIMO techniques. We will coordinate the physical layer, the MAC layer and the network layer for cross-layer evaluation. Performance analysis and simulation results show that throughput and packet loss ratio will have different …
Measurement And Modeling Of 1/F Noise In Mosfet Devices With High-Κ Material As The Gate Dielectric, Tanvir Hasan Morshed
Measurement And Modeling Of 1/F Noise In Mosfet Devices With High-Κ Material As The Gate Dielectric, Tanvir Hasan Morshed
Electrical Engineering Dissertations
A new 1/f noise model has been developed for MOSFET devices with high-? gate stack. To investigate the impacts of nitridation, MOSFETs with nitrided high-? dielectric was used. These devices were provided by Texas Instruments, having four different interfacial layer thicknesses with a stack composition of SiON/HfSiON. The dominant mechanism affecting the noise behavior of these devices was experimentally determined to be correlated number and mobility fluctuation. The impact of remote phonon scattering was investigated in the temperature range of 172K to 300K. It has been observed that the mobility characteristics of these devices were significantly affected by remote phonon …
The Effect Of Temperature On Fiber Composite Bridge Decks, Mahesh Gajula Nagabhushanam
The Effect Of Temperature On Fiber Composite Bridge Decks, Mahesh Gajula Nagabhushanam
Civil Engineering Theses
The use of Fiber composite honeycomb structure's as bridge decks gained importance, because of its low light weight and ease of installation. In this study, The Fiber composite bridge decks were subjected to thermal gradients. The Fiber composite bridge decks were fabricated in sizes of 2 feet x 8 feet x .5 feet and 4 feet x 8 feet x .5 feet specimens by Kansas structural composites Inc. The program consisted of 3 specimens of size 2 feet x 8 feet x .5 feet with ribs oriented along longitudinal direction, 3 specimens of size 2 feet x 8 feet x …
Localization Of Biliary Tree Structures By Use Of Photon Diffusion Models, Dharmendra Nadkar
Localization Of Biliary Tree Structures By Use Of Photon Diffusion Models, Dharmendra Nadkar
Bioengineering Theses
A novel computational methodology is proposed for the intraoperative localization of biliary tree structures by means of spectrally resolved near-infrared reflectance measurements. As these structures are embedded in fatty tissue, they cannot be visualized directly, which results in inadvertent injuries during a cholecystectomy operation. Localizing the biliary tree intraoperatively is therefore an important clinical problem. Successful clinical implementation of an imaging system which could attain this goal would reduce surgical time, improve patient safety, and minimize the risk of complications and expenses attributable to the current standard practice of intraoperative cholangiography. It is hoped that the work presented here will …
Ductile Lightweight Concrete For Lightweight Structural Application, Ake Piyamaikongdech
Ductile Lightweight Concrete For Lightweight Structural Application, Ake Piyamaikongdech
Civil Engineering Theses
This study developed a ductile concrete for precast wall systems which are capable of resisting high wind in excess of 500 mph. The developed concrete mix design consists of sand, cement, glass fiber, and a foaming agent to produce lightweight concrete in the range of 87 pcf (1392 kg/m3) to 90 pcf (1440 kg/m3). A comprehensive testing program for evaluation of the developed concrete material was undertaken. The mix designs were prepared both in the laboratory and in the mix truck with drum capacity of 27 ft3 (0.77 m3), and 177.6 ft3 (5 m3), respectively. The large concrete batches using …
Trends Of Vehicular Emissions For Clean Air Associates Precombustion Retrofit Device, Jaya Vani Nagireddi
Trends Of Vehicular Emissions For Clean Air Associates Precombustion Retrofit Device, Jaya Vani Nagireddi
Civil Engineering Theses
The research study objective was to find if there was any reduction in onboard exhaust emissions from a light duty passenger car (2007 Dodge Charger) with a Clean Air Catalytic Converter manufactured by Clean Air Associates, Inc. The research was conducted by the Civil and Environmental Engineering Department, University of Texas at Arlington as part of the North Central Texas Council of Governments Aftermarket Technology and Fuel Additive Research Program. Initially, emissions of pollutants were measured without the Clean Air Associates' retrofit device, called Baseline testing. A Horiba OBS-1300 On-Board System measured concentrations of the pollutants NOx, CO, CO2 and …
Thermal Enhancement Of Stacked Dice Replacing Wire Bonds With Through Silicon Vias At Location Of Die Pads, Venkata Chepuri Krishna Teja
Thermal Enhancement Of Stacked Dice Replacing Wire Bonds With Through Silicon Vias At Location Of Die Pads, Venkata Chepuri Krishna Teja
Mechanical and Aerospace Engineering Theses
Through Silicon vias can offer quick time to market of circuits designed in a modular manner and can also be used to customize the product according to the needs of the customers. This gives a way to avoid both excess inventory risks and larger footprints. A through silicon via could be described as, a vertical component through which a backside interconnect for a pair of bonded wafers forming a wafer stack is ultimately cut into a number of stacked dice. Various embodiments have been patented [1, 2] but implementation of these architectures can be inhibited based on thermal, mechanical and …
Numerical Simulation Of Magnetohydrodynamics, Takahiro Sonoda
Numerical Simulation Of Magnetohydrodynamics, Takahiro Sonoda
Mechanical and Aerospace Engineering Theses
Use of electromagnetic fields has been shown to be an effective way to control the behavior of electrically conducting fluids. Specifically, the modification of the boundary layer profile with electromagnetic fields can yield performance improvements such as reduced drag and improved heat transfer. Though this approach has been demonstrated computationally and experimentally with conducting liquids (i.e. seawater), application to aerodynamic devices operating in air has not seen the same success. Through the use of numerical simulation and eventually optimization, we hope to develop efficient designs that are effective for boundary layer control for low temperature conducting gases (non-thermal plasmas). The …
Thermal Stresses Of Composite Beams With Rectangular And Tubular Cross-Sections, Chia-Wei Su
Thermal Stresses Of Composite Beams With Rectangular And Tubular Cross-Sections, Chia-Wei Su
Mechanical and Aerospace Engineering Theses
Closed-form analytical solutions for laminated composite beams with tubular and rectangular cross-sections are developed for evaluating the thermal induced stresses. The derivations are based on modified lamination theory and parallel axis theorem. The present approach includes variation of ply stiffness along the contour of the cross-section. The interlaminar shear stress of cantilever composite beam with rectangular cross-section under a transverse load is analytically proved to be independent of temperature change in uniform temperature environment. Three-dimensional finite element models for computing thermal stresses of both cross-sections are developed using commercial software package ANSYS 10. The results obtained from analytical solutions give …
Multi-Objective Evaluation Of Dynamic Facility Layout Using Ant Colony Optimization, Gary Yu-Hsin Chen
Multi-Objective Evaluation Of Dynamic Facility Layout Using Ant Colony Optimization, Gary Yu-Hsin Chen
Industrial, Manufacturing, and Systems Engineering Dissertations
The Dynamic Facility Layout Problem (DFLP) deals with changes of facility layout throughout time. As an extension to Static Facility Layout Problem (SFLP), it has gathered increasing interests lately. Facility layouts are constantly modified over time either to meet customers' changing demands in product designs and functionalities or to keep pace with technological innovations. Manufacturers must stay flexible and agile and frequent facility layout changes are needed. Since there is often insufficient time and insufficient funding to build a new manufacturing plant, it is often necessary to rearrange the current plant layout. Even though the rearrangement of plant layout can …