Engineering Commons^™

Experimental Studies On The Determination Of Acoustic Bulk Material Properties And Transfer Impedance, Wanlu Li

Theses and Dissertations--Mechanical and Aerospace Engineering

Soft trim absorbing parts (i.e., headliners, backwalls, side panels, etc.) are normally comprised of different layers including films, adhesives, foams and fibers. Several approaches to determine the complex wavenumber and characteristic impedance for porous sound absorbing materials are surveyed and the advantages and disadvantages of each approach are discussed. It is concluded that the recently documented three-point method produces the smoothest results. It is also shown that measurement of the flow resistance and the use of empirical equations is sufficient for many common materials. Following this, the transfer impedance of covers, adhesives, and densified layers are measured using an impedance …

Multidimensional Modeling Of Pyrolysis Gas Transport Inside Orthotropic Charring Ablators, Haoyue Weng

Theses and Dissertations--Mechanical and Aerospace Engineering

During hypersonic atmospheric entry, spacecraft are exposed to enormous aerodynamic heat. To prevent the payload from overheating, charring ablative materials are favored to be applied as the heat shield at the exposing surface of the vehicle. Accurate modeling not only prevents mission failures, but also helps reduce cost. Existing models were mostly limited to one-dimensional and discrepancies were shown against measured experiments and flight-data. To help improve the models and analyze the charring ablation problems, a multidimensional material response module is developed, based on a finite volume method framework. The developed computer program is verified through a series of test-cases, …

Fabrication Of Magnetic Two-Dimensional And Three-Dimensional Microstructures For Microfluidics And Microrobotics Applications, Hui Li

Theses and Dissertations--Mechanical and Aerospace Engineering

Micro-electro-mechanical systems (MEMS) technology has had an increasing impact on industry and our society. A wide range of MEMS devices are used in every aspects of our life, from microaccelerators and microgyroscopes to microscale drug-delivery systems. The increasing complexity of microsystems demands diverse microfabrication methods and actuation strategies to realize. Currently, it is challenging for existing microfabrication methods—particularly 3D microfabrication methods—to integrate multiple materials into the same component. This is a particular challenge for some applications, such as microrobotics and microfluidics, where integration of magnetically-responsive materials would be beneficial, because it enables contact-free actuation. In addition, most existing microfabrication methods …

Heat Transfer Characteristics In Wildland Fuelbeds, Justin English

Theses and Dissertations--Mechanical and Aerospace Engineering

The fundamental physics governing wildland fire spread are still largely misunderstood. This thesis was motivated by the need to better understand the role of radiative and convective heat transfer in the ignition and spread of wildland fires. The focus of this work incorporated the use of infrared thermographic imaging techniques to investigate fuel particle response from three different heating sources: convective dominated heating from an air torch, radiative dominated heating from a crib fire, and an advancing flame front in a laboratory wind tunnel test. The series of experiments demonstrated the uniqueness and valuable characteristics of infrared thermography to reveal …

Laboratory Scale Concept Validation And Evaluation Of Compromising Plant Nodal Integrity As A Means To Increase Bale Density, Aaron P. Turner

Theses and Dissertations--Biosystems and Agricultural Engineering

Transportation costs represent a significant role in the economics of packaged hay and biomass crops. The material’s low bulk density limits transportation efficiency. Density is currently limited by the ability of the baling twine to withstand the expansion forces generated by the baled material shortly after it is ejected from the bale chamber. It was hypothesized that compromising the structure of the plant, particularly the plant nodes could reduce the amount of energy stored in the material as it is compressed and thereby reduce the material’s elastic response to compression. Literature pertinent to the biomass material’s behavior in compression was …

A Hypernet Architecture, Shufeng Huang

Theses and Dissertations--Computer Science

Network virtualization is becoming a fundamental building block of future Internet architectures. By adding networking resources into the “cloud”, it is possible for users to rent virtual routers from the underlying network infrastructure, connect them with virtual channels to form a virtual network, and tailor the virtual network (e.g., load application-specific networking protocols, libraries and software stacks on to the virtual routers) to carry out a specific task. In addition, network virtualization technology allows such special-purpose virtual networks to co-exist on the same set of network infrastructure without interfering with each other.

Although the underlying network resources needed to support …

Nuclei/Cell Detection In Microscopic Skeletal Muscle Fiber Images And Histopathological Brain Tumor Images Using Sparse Optimizations, Hai Su

Theses and Dissertations--Computer Science

Nuclei/Cell detection is usually a prerequisite procedure in many computer-aided biomedical image analysis tasks. In this thesis we propose two automatic nuclei/cell detection frameworks. One is for nuclei detection in skeletal muscle fiber images and the other is for brain tumor histopathological images.

For skeletal muscle fiber images, the major challenges include: i) shape and size variations of the nuclei, ii) overlapping nuclear clumps, and iii) a series of z-stack images with out-of-focus regions. We propose a novel automatic detection algorithm consisting of the following components: 1) The original z-stack images are first converted into one all-in-focus image. 2) A …

Field Implementation Of Phanerochaete Chrysosporium Biomass Pretreatment: Fungal Identification And Inoculation Techniques, Bobby D. Carey Jr

Theses and Dissertations--Biosystems and Agricultural Engineering

Scaling biological pretreatment from the bench scale to the production scale may be more economical if unsterilized feedstock are used, however these allow for microbial competition from contaminates. An accurate and rapid method for identifying the desired biological pretreatment organism is necessary to confirm the presence of the desired organism when contaminates are morphologically similar to the target organism. Traditional methods, such as visual identification, sequencing, and selective plating can be time consuming and are sometimes still inconclusive. Based on methods described in the literature, plasmid DNA containing the marker genes gus (�-glucuronidase), LacZ, and gfp (green fluorescence protein) …

Fault Location Algorithms, Observability And Optimality For Power Distribution Systems, Wanjing Xiu

Theses and Dissertations--Electrical and Computer Engineering

Power outages usually lead to customer complaints and revenue losses. Consequently, fast and accurate fault location on electric lines is needed so that repair work can be carried out as fast as possible.

Chapter 2 describes novel fault location algorithms for radial and non-radial ungrounded power distribution systems. For both types of systems, fault location approaches using line to neutral or line to line measurements are presented. It’s assumed that network structure and parameters are known, so that during-fault bus impedance matrix of the system can be derived. Functions of bus impedance matrix and available measurements at substation are formulated, …

Prediction Model To Estimate The Zero Crossing Point For Faulted Waveforms, Md. Shakawat Hossan

Theses and Dissertations--Electrical and Computer Engineering

In any power system, fault means abnormal flow of current. Insulation breakdown is the cause of fault generation. Different factors can cause the breakdown: Wires drifting together in the wind, Lightning ionizing air, wires with contacts of animals and plants, Salt spray or pollution on insulators. The common type of faults on a three phase system are single line-to-ground (SLG), Line-to-line faults (LL), double line-to-ground (DLG) faults, and balanced three phase faults. And these faults can be symmetrical (balanced) or Unsymmetrical (imbalanced).In this Study, a technique to predict the zero crossing point has been discussed and simulated. Zero crossing point …

Robomirror: A Simulated Mirror Display With A Robotic Camera, Yuqi Zhang

Theses and Dissertations--Electrical and Computer Engineering

Simulated mirror displays have a promising prospect in applications, due to its capability for virtual visualization. In most existing mirror displays, cameras are placed on top of the displays and unable to capture the person in front of the display at the highest possible resolution. The lack of a direct frontal capture of the subject's face and the geometric error introduced by image warping techniques make realistic mirror image rendering a challenging problem. The objective of this thesis is to explore the use of a robotic camera in tracking the face of the subject in front of the display to …

Effects Of Sodium Hydroxide Pretreatment On Structural Components Of Biomass, Alicia A. Modenbach, Sue E. Nokes

Biosystems and Agricultural Engineering Faculty Publications

Pretreatment is a unit operation in the conversion of biomass to valuable products that utilizes various combinations of conditions, including chemicals, heat, pressure, and time, to reduce the recalcitrance of lignocellulose. Many such pretreatments have been developed over the years, as the operating conditions can be adapted so that lignocellulose is modified in ways unique to each pretreatment. By tailoring pretreatment conditions to achieve these modifications, the types of final products produced can be controlled. The purpose of this review is to provide a consolidated source of information for sodium hydroxide effects on lignocellulose. The structural characteristics of lignocellulose and …

Modeling And Validation Of A Synchronous-Machine/Controlled-Rectifier System, Kyle A. Hord

Theses and Dissertations--Electrical and Computer Engineering

The hardware validation of a novel average-value model (AVM) for the simulation of a synchronous-generator/controlled rectifier system is presented herein. The generator is characterized using genetic algorithm techniques to fit standstill frequency response (SSFR) measurements to q and d-axis equivalent circuits representing the generator in the rotor reference frame. The generator parameters form the basis of a detailed model of the system, from which algebraic functions defining the parametric AVM are derived. The average-value model is compared to the physical system for a variety of loading and operating conditions including step load change, change in delay angle, and external closed-loop …

Model Analysis And Predictive Control Of Double Electrode Submerged Arc Welding Process For Fillet Joints With Root Opening, Yi Lu

Theses and Dissertations--Electrical and Computer Engineering

Submerged Arc Welding (SAW) for fillet joints is one of the major applications in the shipbuilding industry. Due to the requirement for the weld size, a sufficient amount of metal must be deposited. In conventional SAW process, the heat input is proportional to the amount of metal melted and is thus determined by the required weld size. To meet this requirement, an excessive amount of heat is applied causing large distortions on the welded structures whose follow-up straightening is highly costly. In order to reduce the needed heat input, Double-Electrode (DE) technology has been practiced creating the Double-Electrode SAW (DE-SAW) …

A Universal Background Subtraction System, Hasan Sajid

Theses and Dissertations--Electrical and Computer Engineering

Background Subtraction is one of the fundamental pre-processing steps in video processing. It helps to distinguish between foreground and background for any given image and thus has numerous applications including security, privacy, surveillance and traffic monitoring to name a few. Unfortunately, no single algorithm exists that can handle various challenges associated with background subtraction such as illumination changes, dynamic background, camera jitter etc. In this work, we propose a Multiple Background Model based Background Subtraction (MB²S) system, which is universal in nature and is robust against real life challenges associated with background subtraction. It creates multiple background models …

Machine-Human Cooperative Control Of Welding Process, Weijie Zhang

Theses and Dissertations--Electrical and Computer Engineering

An innovative auxiliary control system is developed to cooperate with an unskilled welder in a manual GTAW in order to obtain a consistent welding performance. In the proposed system, a novel mobile sensing system is developed to non-intrusively monitor a manual GTAW by measuring three-dimensional (3D) weld pool surface. Specifically, a miniature structured-light laser amounted on torch projects a dot matrix pattern on weld pool surface during the process; Reflected by the weld pool surface, the laser pattern is intercepted by and imaged on the helmet glass, and recorded by a compact camera on it. Deformed reflection pattern contains the …

Development Of Northrop-Grumman Mark Viie Training Unit And Wireless Video System For Use In Immersive Environments, Randall Lee Lewis

Theses and Dissertations--Electrical and Computer Engineering

A training unit has been developed that allows NVESD researchers to develop training simulations within virtual environments to enhance infantry skill and awareness. A ground station was developed to house a computer, power system, and video transmission system. This station will allow for a remote operator to wirelessly send a video/audio stream to the handset. The ground station also allows the use of external video and audio inputs to be sent using onboard converters. Different wireless frequencies were evaluated to determine the best for long-range transmission of content. A handset was developed from a carbon fiber prototype shell. The handset …

Multi-Domain, Multi-Objective-Optimization-Based Approach To The Design Of Controllers For Power Electronics, Jing Shang

Theses and Dissertations--Electrical and Computer Engineering

Power converter has played a very important role in modern electric power systems. The control of power converters is necessary to achieve high performance. In this study, a dc-dc buck converter is studied. The parameters of a notional proportional-integral controller are to be selected. Genetic algorithms (GAs), which have been widely used to solve multi-objective optimization problems, is used in order to locate appropriate controller design. The control metrics are specified as phase margin in frequency domain and voltage error in time-domain. GAs presented the optimal tradeoffs between these two objectives. Three candidate control designs are studied in simulation and …

A Method For Non-Invasive, Automated Behavior Classification In Mice, Using Piezoelectric Pressure Sensors, Steven R. Gooch

Theses and Dissertations--Electrical and Computer Engineering

While all mammals sleep, the functions and implications of sleep are not well understood, and are a strong area of investigation in the research community. Mice are utilized in many sleep studies, with electroencephalography (EEG) signals widely used for data acquisition and analysis. However, since EEG electrodes must be surgically implanted in the mice, the method is high cost and time intensive. This work presents an extension of a previously researched high throughput, low cost, non-invasive method for mouse behavior detection and classification. A novel hierarchical classifier is presented that classifies behavior states including NREM and REM sleep, as well …

Investigation Of Protection Issues And Method For The Distribution System With Distributed Generations, Ke Xu

Theses and Dissertations--Electrical and Computer Engineering

Because DGs are introduced into distribution systems, the coordination of fuses and reclosers doesn’t work well. It means the original protection schemes are not available for the distribution systems with DGs. This thesis paper presents the study on the impacts of DGs on the fault current and voltage in the distribution system by the simulation of a model distribution system. After we study the impacts of DG on distribution systems, there is an introduction of current several current protection schemes and fault locations methods. At last, an adaptive protection scheme with a more efficient fault location method for the distribution …

Reference Compensation For Localized Surface-Plasmon Resonance Sensors, Neha Nehru

Theses and Dissertations--Electrical and Computer Engineering

Noble metal nanoparticles supporting localized surface plasmon resonances (LSPR) have been extensively investigated for label free detection of various biological and chemical interactions. When compared to other optical sensing techniques, LSPR sensors offer label-free detection of biomolecular interactions in localized sensing volume solutions. However, these sensors also suffer from a major disadvantage – LSPR sensors remain highly susceptible to interference because they respond to both solution refractive index change and non-specific binding as well as specific binding of the target analyte. These interactions can severely compromise the measurement of the target analyte in a complex unknown media and hence limit …

Virtualized Welding Based Learning Of Human Welder Behaviors For Intelligent Robotic Welding, Yukang Liu

Theses and Dissertations--Electrical and Computer Engineering

Combining human welder (with intelligence and sensing versatility) and automated welding robots (with precision and consistency) can lead to next generation intelligent welding systems. In this dissertation intelligent welding robots are developed by process modeling / control method and learning the human welder behavior.

Weld penetration and 3D weld pool surface are first accurately controlled for an automated Gas Tungsten Arc Welding (GTAW) machine. Closed-form model predictive control (MPC) algorithm is derived for real-time welding applications. Skilled welder response to 3D weld pool surface by adjusting the welding current is then modeled using Adaptive Neuro-Fuzzy Inference System (ANFIS), and compared …

Measurement And Modeling Of Humidity Sensors, Jingbo Tong

Theses and Dissertations--Electrical and Computer Engineering

Humidity measurement has been increasingly important in many industries and process control applications. This thesis research focus mainly on humidity sensor calibration and characterization. The humidity sensor instrumentation is briefly described. The testing infrastructure was designed for sensor data acquisition, in order to compensate the humidity sensor’s temperature coefficient, temperature chambers using Peltier elements are used to achieve easy-controllable stable temperatures. The sensor characterization falls into a multivariate interpolation problem. Neuron networks is tried for non-linear data fitting, but in the circumstance of limited training data, an innovative algorithm was developed to utilize shape preserving polynomials in multiple planes in …

Single Ended Traveling Wave Based Fault Location Using Discrete Wavelet Transform, Jin Chang

Theses and Dissertations--Electrical and Computer Engineering

In power transmission systems, locating faults is an essential technology. When a fault occurs on a transmission line, it will affect the whole power system. To find the fault location accurately and promptly is required to ensure the power supply. In this paper, the study of traveling wave theory, fault location method, Karrenbauer transform, and Wavelet transform is presented. This thesis focuses on single ended fault location method. The signal processing technique and evaluation study are presented. The MATLAB SimPowerSystem is used to test and simulate fault scenarios for evaluation studies.

Frequency Tracking And Phasor Estimation Using Least Squares And Total Least Squares Algorithms, Hengdao Guo

Theses and Dissertations--Electrical and Computer Engineering

System stability plays an important role in electric power systems. With the development of electric power system, the scale of the electric grid is now becoming larger and larger, and many renewable energy resources are integrated in the grid. However, at the same time, the stability and safety issues of electric power system are becoming more complicated. Frequency and phasors are two critical parameters of the system stability. Obtaining these two parameters have been great challenges for decades. Researchers have provided various kinds of algorithms for frequency tracking and phasor estimation. Among them, Least Squares (LS) algorithm is one of …

Volume And Surface Integral Equations For Solving Forward And Inverse Scattering Problems, Xiande Cao

Theses and Dissertations--Electrical and Computer Engineering

In this dissertation, a hybrid volume and surface integral equation is used to solve scattering problems. It is implemented with RWG basis on the surface and the edge basis in the volume. Numerical results shows the correctness of the hybrid VSIE in inhomogeneous medium. The MLFMM method is also implemented for the new VSIEs.

Further more, a synthetic apature radar imaging method is used in a 2D microwave imaging for complex objects. With the mono-static and bi-static interpolation scheme, a 2D FFT is applied for the imaging with the data simulated with VSIE method. Then we apply a background cancelling …

Error Control And Efficient Memory Management For Sparse Integral Equation Solvers Based On Local-Global Solution Modes, Jun-Shik Choi

Theses and Dissertations--Electrical and Computer Engineering

This dissertation presents and analyzes two new algorithms for sparse direct solution methods based on the use of local-global solution (LOGOS) modes. One of the new algorithms is a rigorous error control strategy for LOGOS-based matrix factorizations that utilize overlapped, localizing modes (OL-LOGOS) on a shifted grid. The use of OL-LOGOS modes is critical to obtaining asymptotically efficient factorizations from LOGOS-based methods. Unfortunately, the approach also introduces a non-orthogonal basis function structure. This can cause errors to accumulate across levels of a multilevel implementation, which has previously posed a barrier to rigorous error control for the OL-LOGOS factorization method. This …

Proposed Middleware Solution For Resource-Constrained Distributed Embedded Networks, Jason T. Rexroat

Theses and Dissertations--Electrical and Computer Engineering

The explosion in processing power of embedded systems has enabled distributed embedded networks to perform more complicated tasks. Middleware are sets of encapsulations of common and network/operating system-specific functionality into generic, reusable frameworks to manage such distributed networks. This thesis will survey and categorize popular middleware implementations into three adapted layers: host-infrastructure, distribution, and common services. This thesis will then apply a quantitative approach to grading and proposing a single middleware solution from all layers for two target platforms: CubeSats and autonomous unmanned aerial vehicles (UAVs). CubeSats are 10x10x10cm nanosatellites that are popular university-level space missions, and impose power and …

Multifrequency Averaging In Power Electronic Systems, Fei Pan

Theses and Dissertations--Electrical and Computer Engineering

Power electronic systems have been widely used in the electrical power processing for applications with power levels ranging from less than one watt in battery-operated portable devices to more than megawatts in the converters, inverters and rectifiers of the utility power systems. These systems typically involve the passive elements such as inductors, capacitors, and resistors, the switching electronic components such as IGBTs, MOSFETS, and diodes, and other electronic circuits. Multifrequency averaging is one of the widely used modeling and simulation techniques today for the analysis and design of power electronic systems. This technique is capable of providing the average behavior …

Humidity Sensor Circuit Using Real Time Operating System (Freertos) Kernel, Bojie Chen

Theses and Dissertations--Electrical and Computer Engineering

A humidity sensor can be used to measure the moisture content of the environment. The physical change of the sensor expresses as the change of electrical property like capacitance, resistance, voltage, current, frequency, etc. In order to process these analog signals digitally, microprocessor is involved in the measurement. This thesis presents design of a circuit to measure low moisture levels. The 16-bit RISC mixed signal microcontroller MSP430F249 from Texas Instruments will be used. The circuit has good performance at extremely low humidity levels.

Meanwhile, a small real time operating system kernel FreeRTOS, a market leading RTOS from Real Time Engineer …