Engineering Commons^™

Data Mining-Driven Approahces For Process Monitoring And Diagnosis, Thuntee Sukchotrat

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

The objective of this dissertation is to develop a new set of efficient process monitoring and diagnostic tools through their integration with data mining algorithms. Statistical process control (SPC) is one of the most widely used techniques for quality control. Although traditional SPC tools are effective in simple manufacturing processes that generate a small volume of independent data, these tools falter when confronted by the large streams of complex and correlated data found in modern manufacturing systems. As the limitations of SPC methodology become increasingly obvious in the face of ever more complex manufacturing processes, data mining, because of its …

The Thermal Effects Of Self Heating Of Transistors On Analog Amplifier Design And Evaluation, Kamal Ranjan Sinha

Electrical Engineering Dissertations - Archive

Electrothermal effects play a major role in the performance of modern silicon-on-insulator (SOI) bipolar junction transistors (BJTs). This research work examines the influence of electrothermal feedback within a single device and within a circuit composed of such devices. Specifically, the frequency-domain thermal effects of self-heating in SOI BJTs on the performance of analog integrated circuits, with emphasis on current mirrors, and current-feedback operational amplifiers (CFOA), are investigated through analytical formulation, simulation, and measurement.For the extensive analysis and characterization of self-heating thermal effects, the Vertical Bipolar Inter-Company (VBIC) models for SOI BJTs are developed from fundamental physical device considerations. Extensive simulations …

Thermal Characterization Of Dielectrically Isolated Bipolar Junction Transistor, Daewoo Kim

Electrical Engineering Dissertations - Archive

Since the integrated circuit (IC) was invented in 1960, the operating speed of semiconductor devices has steadily increased and the number of semiconductor devices in an IC chip has grown by a size reduction of the devices. This trend has lead to the rapid increase of power consumption and heat generation. As a result of this increase, thermal characterization of semiconductor devices has become more important.It is especially important to consider thermal characteristics of the dielectrically isolated complementary bipolar junction transistor (DIBJT) which offers many advantages. However, a major disadvantage of this device is an increase in self-heating. Because the …

Functional Data Analysis For Environmental And Biomedical Problems, Chivalai Temiyasathit

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Vast amounts of data are being generated due to the development of sensing technology. Among those, one of the common types of data usually found in various discipline is the functional data. Because the functional data are generally collected in a wide area of interest over a relatively long period, such analyses should take into account both temporal and spatial characteristics. Furthermore, combinations of observations from multiple locations, each with a large number of serially correlated values, lead to a situation that poses a great challenge to analytical and computational capabilities. In contrast, data obtained from medical and biomedical researches …

Thermal Effects And Analysis On Analog Integrated Circuit Design, Ardasheir Sayek Rahman

Electrical Engineering Theses - Archive

Analog circuit design is an art of circuit designing. With technology becoming more advance and size of devices shrinking, circuit designing has becoming a real chance for the designers to meet up the demands in the market. Density of device transistor is rapidly increasing leading to thermal runaway issues and increasing operational speed of the transistors. Thus transistors are more sensitive to temperature changes, therefore requiring a more sensitive and accurate modeling of the thermal effects of the device as well as its adjacent devices. This research is on the thermal modeling of dielectric bipolar junction devices. It looks into …

The Highly Similar Arabidopsis Homologs Of Trithorax Atx1 And Atx2 Encode Proteins With Divergent Biochemical Functions, Abdelaty Saleh, Raul Alvarez-Venegas, Mehtap Yilmaz, Oahn-Le, Guichuan Hou, Monther Sadder, Ayed Al-Abdallat, Yuannan Xia, Guoqinq Lu, Istvan Ladunga, Zoya Avramova

Nebraska Center for Biotechnology: Faculty and Staff Publications

Gene duplication followed by functional specialization is a potent force in the evolution of biological diversity. A comparative study of two highly conserved duplicated genes, ARABIDOPSIS TRITHORAX-LIKE PROTEIN1 (ATX1) and ATX2, revealed features of both partial redundancy and of functional divergence. Although structurally similar, their regulatory sequences have diverged, resulting in distinct temporal and spatial patterns of expression of the ATX1 and ATX2 genes. We found that ATX2 methylates only a limited fraction of nucleosomes and that ATX1 and ATX2 influence the expression of largely nonoverlapping gene sets. Even when coregulating shared targets, ATX1 and ATX2 may employ different …

Nebraska Blueprint – Winter 2007-08

Nebraska Blueprint (Student Publication)

Table of Contents:

Bike Lanes: Making Space for Safety
Engineering: Building a Better Bike
Bridge Safety: A Local Perspective
Alumni Tips: Advice for Undergraduates
Performance: Improving Cyclists
Tech Guru: Internet Browsers br> Student Profile: Daniela Cadore br> Student Profile: Erin Hammons

Nebraska Blueprint - Spring 2008

Nebraska Blueprint (Student Publication)

Table of Contents:

Letter from the Editor
E-Engineering: Environmentalism Tips
Tech Guru: Eye-Fi
E-Engineering by Lt. Col. Jeff Gillen
E-Engineering by Rachel Thorpe
E-Week 2008 - Speaker Jeff Zvolanek
E-Week 2008: Behind the Scenes
E-Week 2008 Responses
E-Week 2008 Awards

Nebraska Blueprint- Winter 2008

Nebraska Blueprint (Student Publication)

Table of Contents:

4 From the Editor

5 The Engineering Library

6 Gasifier and More at Splinter Labs

8 Anechoic Chamber and Scatterometer

10 Surgical Robotics Lab

12 Research Computing Facility and Schorr Center

How Do You Interpret A Confidence Interval?, Paul Savory

Department of Industrial and Management Systems Engineering: Instructional Materials

A confidence interval (CI) is an interval estimate of a population parameter. Instead of estimating the parameter by a single value, a point estimate, an interval likely to cover the parameter is developed. Many student incorrectly interpret the meaning of a confidence interval. This paper offers a quick overview of how to correctly interpret a confidence interval.

Addressing Nonlinear Combustion Instabilities In Highly Dilute Spark Ignition Engine Operation, Brian C. Kaul

Doctoral Dissertations

"Dilute operation is a promising approach for increasing spark-ignition engine efficiency, in the form of either lean burn (air dilution) or EGR (inert dilution). High levels of charge dilution, however, lead to cyclic variability that is largely deterministic in nature. The determinism and nonlinear nature of the system indicate that it should be possible to reduce the cycle-to-cycle variations by implementing an electronic controller. Several needs arise when considering the development of such a controller. Three topics of interest are covered herein. First, a method of analysis for nonlinear dynamical systems is applied to engine data in order to estimate …

Unsteady Flow And Heat Transfer In Periodic Complex Geometries For The Transitional Flow Regime, Li-Kwen Chen

Doctoral Dissertations

"Diesel engines are facing significant challenges with upcoming changes in emissions standards. In general, meeting the increased emission standards will require a larger fraction of the engine heat rejection to occur in the vehicle cooling system. For certain applications, the surface geometry must also be such that it resists particulate fouling, precluding common interrupted surfaces such as louvered fins. Although acceptable continuous surface geometries such as bumped fin geometries are in use, the impacts of changing the parameters of this geometry are unknown. This study investigates the transport characteristics of bumped fins in the transitional flow regime using unsteady multi-dimensional …

Speculation And Hedging With Virtuals, Prasenjit Shil

Doctoral Dissertations

"Virtual bid" and "Virtual offer" are purely financial products offered in certain electricity markets. Theoretically, virtual bids and offers can change the electricity price as the bids and offers are stacked along with the demand and supply, respectively. This dissertation discusses how virtuals can be used to hedge and speculate in the electricity market. A statistical simulation model is developed based on the day-ahead (DA) demand and real time (RT) load data from Midwest Independent Transmission System Operator's (MISO) footprint and DA and RT price observed at Cinergy hub. The simulation models are intended to mimic the load and price …

Design And Optimization Of Abrasive Slurry Feed System, Control Circuit And Jet Drilling Tool For Mining Applications,, Pradeep Nambiath

Doctoral Dissertations

"This dissertation focused on an investigation of small diameter hole drilling using abrasive slurry jet (ASJ) technology. The existing ASJ feed systems were reviewed and found inadequate to satisfy the requirements of an ASJ drill. A novel feed system was designed which improved on existing systems by resolving problems with the inability to perform stop/start operations and ensure precise metering of abrasive feed. This system met standards of consistency and evenness of feed required for machining aircraft component parts for Air Force Research Laboratory (AFRL). Theoretical and experimental analysis of the power of an ASJ stream yielded valuable design information …

Packing Factors Of Feed Products In Storage Structures, Samuel G. Mcneill, Michael D. Montross, Sidney A. Thompson, I. Joseph Ross, Thomas C. Bridges

Biosystems and Agricultural Engineering Faculty Publications

Experiments were conducted to measure the changes in bulk density of cracked corn, corn meal, soybean meal, cotton seed meal, and distillers dried grain (without solubles) when subjected to simulated overburden pressures. All materials were tested at two moisture content levels (approximately 8% and 12% w.b.) and seven pressures between 0 and 69 kPa (0 and 10 psi). A mathematical model was fitted to the data to predict the bulk density of each feed ingredient as a function of pressure and moisture content. These relationships were inserted into a previously developed computer model to predict ingredient packing within conventional storage …

Airflow Resistance Of Wheat Bedding As Influenced By The Filling Method, J. Łukaszuk, M. Molenda, J. Horabik, B. Szot, Michael D. Montross

Biosystems and Agricultural Engineering Faculty Publications

A study was conducted to estimate the degree of variability of the airflow resistance in wheat caused by the filling method, compaction of the sample, and airflow direction. Two types of grain chambers were used: a cylindrical column 0.95 m high and 0.196 m in diameter, and a cubical box of 0.35 m side. All factors examined were found to influence considerably the airflow resistance. Gravitational axial filling of the grain column from three heights (0.0, 0.95 and 1.8 m) resulted in the pressure drops of 1.0, 1.3, and 1.5 kPa at the airflow velocity of 0.3 m/s. Consolidation of …

Groundwater Circulation Well Operation Using Wind Turbine–Generated Energy, Ron Gallagher, Andrew Curtis Elmore

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

An investigation was conducted regarding the potential economic benefits associated with using a wind turbine to power a groundwater circulation well (GCW) at the former Nebraska Ordnance Plant Superfund site. the first phase of the investigation used a 10-kilowatt-rated grid inter-tie wind turbine to partially offset the purchase of electricity from the utility company. the second phase consisted of the conversion of the grid inter-tie system to an off-grid system that stored energy using batteries. during the second phase, the GCW system was operated using either wind turbine power or utility power, and the other system components were operated using …

Enabling Wind Turbine Generators To Participate In Power Grid Frequency Regulation For Enhanced Stability, Hongtao Ma

Doctoral Dissertations

"This dissertation focuses on wind farm frequency regulation capability to maintain the grid frequency stability. Wind plant power controllers are designed and tested for participation in grid frequency restoration. The small signal stability on sub-optimal operating points is analyzed and a de-loaded operating point is proposed.

In the first paper, a new frequency regulation scheme is developed for the wind turbine/generator/converter trio that will provide the capability to participate in restoring frequency in a way similar to the droop response of conventional generators. Output active power adjustment can be realized by both converter and pitch angle control in addition to …

Rational Best-Value Model Based On Expected Performance, Magdy Abdelrahman, Tarek Zayed, Jay Hietpas, Ahmed Elwakil

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The best-value procurement strategy is gaining the interest of federal and state agencies. The strategy increases the value added to a project for each dollar added. A new concept of best value, that is, a rational and flexible model based on expected performance, is presented. The model's flexibility is obvious in the selection of parameters to be included in the contractor selection process and in the determination of their weights. The model's rationality will be achieved through relating all awarded scores to the agency's expected performance. The establishment of the best-value model relies on the past record of the contractor's …

A Framework For Efficient Data Distribution In Peer-To-Peer Networks., Darshan Purandare

Electronic Theses and Dissertations

Peer to Peer (P2P) models are based on user altruism, wherein a user shares its content with other users in the pool and it also has an interest in the content of the other nodes. Most P2P systems in their current form are not fair in terms of the content served by a peer and the service obtained from swarm. Most systems suffer from free rider's problem where many high uplink capacity peers contribute much more than they should while many others get a free ride for downloading the content. This leaves high capacity nodes with very little or no …

Real-Time Realistic Rendering Of Nature Scenes With Dynamic Lighting, Kevin Boulanger

Electronic Theses and Dissertations

Rendering of natural scenes has interested the scientific community for a long time due to its numerous applications. The targeted goal is to create images that are similar to what a viewer can see in real life with his/her eyes. The main obstacle is complexity: nature scenes from real life contain a huge number of small details that are hard to model, take a lot of time to render and require a huge amount of memory unavailable in current computers. This complexity mainly comes from geometry and lighting. The goal of our research is to overcome this complexity and to …

Modeling And Analysis Of Power Mosfets For High Frequency Dc-Dc Converters, Yali Xiong

Electronic Theses and Dissertations

Evolutions in integrated circuit technology require the use of a high-frequency synchronous buck converter in order to achieve low cost, low profile, fast transient response and high power density. However, high frequency operation leads to increased power MOSFET switching losses. Optimization of the MOSFETs plays an important role in improving converter performance. This dissertation focuses on revealing the power loss mechanism of power MOSFETs and the relationship between power MOSFET structure and its power loss. The analytical device model, combined with circuit modeling, cannot reveal the relationship between device structure and its power loss due to the highly non-linear characteristics …

Transient Response Improvement For Multi-Phase Voltage Regulators, Shangyang Xiao

Electronic Theses and Dissertations

Next generation microprocessor (Vcore) requirements for high current slew rates and fast transient response together with low output voltage have posed great challenges on voltage regulator (VR) design . Since the debut of Intel 80X86 series, CPUs have greatly improved in performance with a dramatic increase on power consumption. According to the latest Intel VR11 design guidelines , the operational current may ramp up to 140A with typical voltages in the 1.1V to 1.4V range, while the slew rate of the transient current can be as high as 1.9A/ns [1, 2]. Meanwhile, the transient-response requirements are becoming stringer and stringer. …

Design, Characterization And Compact Modeling Of Novel Silicon Controlled Rectifier (Scr)-Based Devices For Electrostatic Discha, Lifang Lou

Electronic Theses and Dissertations

Electrostatic Discharge (ESD), an event of a sudden transfer of electrons between two bodies at different potentials, happens commonly throughout nature. When such even occurs on integrated circuits (ICs), ICs will be damaged and failures result. As the evolution of semiconductor technologies, increasing usage of automated equipments and the emerging of more and more complex circuit applications, ICs are more sensitive to ESD strikes. Main ESD events occurring in semiconductor industry have been standardized as human body model (HBM), machine model (MM), charged device model (CDM) and international electrotechnical commission model (IEC) for control, monitor and test. In additional to …

Evaluating The Performance Of Animal Shelters: An Application Of Data Envelopment Analysis, Brandy Heyde

Electronic Theses and Dissertations

The focus of this thesis is the application of data envelopment analysis to understand and evaluate the performance of diverse animal welfare organizations across the United States. The results include identification of the most efficient animal welfare organizations, at least among those that post statistics on their operations, and a discussion of various partnerships that may improve the performance of the more inefficient organizations. The Humane Society of the United States estimates that there are 4000 - 6000 independently-run animal shelters across the United States, with an estimated 6-8 million companion animals entering them each year. Unfortunately, more than half …

Defining Risk Assessment Confidence Levels For Use In Project Management Communications, Gary Johnson

Electronic Theses and Dissertations

A review of the literature regarding risk management and effective risk communications identified that very few researchers have addressed risk assessment confidence levels when using risk scoring methods. The focus of this research is to develop a definition of risk assessment confidence levels for use in internal project management communications and to evaluate its usefulness. This research defines risk assessment confidence level as "The degree of certainty that the likelihood or consequence score (assigned by the risk assessor) reflects reality." A specific level of confidence is defined based on the types of analyses that were conducted to determine the risk …

Taming Crowded Visual Scenes, Saad Ali

Electronic Theses and Dissertations

Computer vision algorithms have played a pivotal role in commercial video surveillance systems for a number of years. However, a common weakness among these systems is their inability to handle crowded scenes. In this thesis, we have developed algorithms that overcome some of the challenges encountered in videos of crowded environments such as sporting events, religious festivals, parades, concerts, train stations, airports, and malls. We adopt a top-down approach by first performing a global-level analysis that locates dynamically distinct crowd regions within the video. This knowledge is then employed in the detection of abnormal behaviors and tracking of individual targets …

Stable Optical Frequency Comb Generation And Applications In Arbitrary Waveform Generation, Signal Processing And Optical Data M, Sarper Ozharar

Electronic Theses and Dissertations

This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was ±1 MHz, limited by the …

Digital Signal Processing Techniques For Coherent Optical Communication, Gilad Goldfarb

Electronic Theses and Dissertations

Coherent detection with subsequent digital signal processing (DSP) is developed, analyzed theoretically and numerically and experimentally demonstrated in various fiber-optic transmission scenarios. The use of DSP in conjunction with coherent detection unleashes the benefits of coherent detection which rely on the preservation of full information of the incoming field. These benefits include high receiver sensitivity, the ability to achieve high spectral-efficiency and the use of advanced modulation formats. With the immense advancements in DSP speeds, many of the problems hindering the use of coherent detection in optical transmission systems have been eliminated. Most notably, DSP alleviates the need for hardware …

Meshfree Approximation Methods For Free-Form Optical Surfaces With Applications To Head-Worn Displays, Ozan Cakmakci

Electronic Theses and Dissertations

Compact and lightweight optical designs achieving acceptable image quality, field of view, eye clearance, eyebox size, operating across the visible spectrum, are the key to the success of next generation head-worn displays. The first part of this thesis reports on the design, fabrication, and analysis of off-axis magnifier designs. The first design is catadioptric and consists of two elements. The lens utilizes a diffractive optical element and the mirror has a free-form surface described with an x-y polynomial. A comparison of color correction between doublets and single layer diffractive optical elements in an eyepiece as a function of eye clearance …