Engineering Commons^™

Temporal Calcium Response Of Jurkat Cells To Nanosecond Pulsed Electric Fields, Shaka Shakar Scarlett

Electrical & Computer Engineering Theses & Dissertations

Nanosecond pulsed electric fields (nsPEF) of megavolt per meter field strengths can interact with subcellular structures [1] and consequently trigger a variety of biological events. The exposure can induce apoptosis, as well as an array of differential "sub-lethal effects." One of the most sensitive and immediate responses is the increase in intracellular calcium concentration in pulsed cells [2], [3][4].We investigated the response of Jurkat cells (a human leukemic cell line) to nsPEFs of 60 ns duration and field strengths from 25 tol00 kV/cm. The development of the induced calcium response in individual cells was studied by spinning-disc confocal microscopy with …

Spacecraft Trajectory Design For Short Duration Near Earth Asteroid Missions, Synthia Mirlin Findlay

Mechanical & Aerospace Engineering Theses & Dissertations

Design of orbital trajectories using patched conic approximation methodology for short duration missions to newly detected, incoming near Earth asteroids, which are on close approach trajectories with Earth, is the focus of this thesis. The primary purpose for such missions is two fold. First, near Earth asteroids provide unique mission opportunities for solar system science where the celestial body of interest transits to Earth proximity and is studied in situ by probes having short duration trajectories, rather than sending long distance probes to the celestial body. Second, improved characterization of asteroid properties, compositions, and orbital states for reduction of uncertainties …

Unsteady Numerical Analysis Of A 2-Dimensional, Hydrogen Fueled, Air-Breathing Dual Mode Scramjet Engine, Nathan John Luetke

Mechanical & Aerospace Engineering Theses & Dissertations

Upstream interaction in a transient two-dimensional dual-mode scramjet engine is examined. This research is performed to compare completed and verified steady results with unsteady results in order to have a better understanding of the flow field. The flow is solved numerically with a Mach 2.5 free stream and sonic normal injection of hydrogen fuel emanating from facing walls while no symmetry assumptions were made. The free stream is modeled as vitiated air in order to produce comparable flight enthalpies and stagnation properties at the combustor inlet during flight conditions of approximately Mach 7. The vitiated stream consists of water vapor …

Life Cycle Impact Assessment Method For Early Design Phase Of Industrial Products, Harpreet Singh Multani

Mechanical & Aerospace Engineering Theses & Dissertations

The objective of this thesis is to develop a simplified life cycle impact assessment method that can reliably and quickly provide the values of Eco-indicator 99 single score, the Eco-indicator damage categories score (human health, ecosystem quality, resource depletion), environmental impacts like global warming, ozone depletion, acidification, eutrophication, photochemical oxidants potential of the product/process, which could be used in the initial design stages for alternative design comparisons and product improvements, thus leading towards green manufacturing.

To achieve this, a variety of products have been chosen and the life cycle inventory data is gathered from the environmental product declarations that are …

Statistical Interpretation Of Mohr-Coulomb Theory As Applied To Fracture In Brittle Materials Containing Cracks, Mudit J. Monsi

Mechanical & Aerospace Engineering Theses & Dissertations

Fracture in brittle materials containing pre-existing cracks was studied. The probability of of crack growth under both shear and tensile stresses was determined for an arbitrary distribution of crack sizes. Two different crack orientation distributions, random and uniform, as well as friction were also taken into account. The material's reliability was assumed to depend on the number of active cracks at a particular stress level, and this was expressed as an arbitrary 2-parameter Weibull distribution. Two new and efficient methods for calculating crack growth probabilities based on spherical triangles and spherical caps were developed. They utilized normalized stress coordinates and …

Energy Based Method For Generation Of Optimum Flight Paths, Michael Jon Acheson

Mechanical & Aerospace Engineering Theses & Dissertations

One key to increasing aviation safety and airport efficiency is the proper management of aircraft energy states. Aircraft accident statistics are replete with examples of aircraft that crossed the runway threshold with excessive energy or maintained insufficient energy to reach the runway. This trend has resulted in aircrews that are trained in conservative energy management that trades efficiency for simplicity. Additionally, traditional aircraft flight displays provide limited aircraft energy state cues that do not enable efficient management of aircraft energy states. In this thesis, a method for generating global optimum flight profiles is demonstrated that yields results that can be …

Performance Analysis Of Recoverable Flight Control Systems Subject To Neutron-Induced Upsets Using Hybrid Dynamical Models, Hong Zhang

Electrical & Computer Engineering Theses & Dissertations

It has been observed that atmospheric neutrons can produce single-event upsets in digital flight control hardware. Potentially, they can reduce system performance and introduce a safety hazard. One experimental system-level approach investigated to help mitigate the effects of these upsets is NASA Langley's Recoverable Computer System. It employs rollback error recovery using dual-lock-step processors together with new fault tolerant architectures and communication subsystems.

In this dissertation, a class of stochastic hybrid dynamical models, which consists of a jump-linear system and a stochastic finite-state automaton, is used to describe the performance of a Boeing 737 aircraft system in closed-loop with a …

An Operational Model For Mobile Sensor Cloud Management, Indrajeet Kalyankar

Electrical & Computer Engineering Theses & Dissertations

Mobile sensors provide a safe, cost effective method for gathering information in hazardous environments. When the hazardous environment is either unexplored, such as the surface of Mars, or unanticipated, such as the result of chemical contamination, it is desirable for a system to gather information with a minimal amount of outside control (localization, decision control, etc.) and prepositioned sensors. If one takes a look at the number of the sensors deployed on a scale, at the lower end is the sole, multipurpose sensor unit. The upper end deals with hordes of inexpensive, expendable sensors. In the middle, a cluster of …

Micron-Level Actuator For Thermal-Fluid Control In Microchannels, Nurhak Erbas

Mechanical & Aerospace Engineering Theses & Dissertations

Effectiveness of an actuator is investigated for thermal-flow control in microchannels. First, simulations of a single actuator in a quiescent external medium are performed in order to study the parameters characterizing the synthetic jet flow from the actuator. For this purpose, a simplified, two-dimensional configuration is considered. The membrane motion is modeled in a realistic manner as a moving boundary in order to accurately compute the flow inside the actuator cavity. The geometric and actuation parameters of the actuator are investigated to define the effectiveness of the jet flow. The study is done initially at macro scales. Then, the flow …

High Performance Queueing And Scheduling In Support Of Multicasting In Input-Queued Switches, Weiying Zhu

Electrical & Computer Engineering Theses & Dissertations

Due to its mild requirement on the bandwidth of switching fabric and internal memory, the input-queued architecture is a practical solution for today's very high-speed switches. One of the notoriously difficult problems in the design of input-queued switches with very high link rates is the high performance queueing and scheduling of multicast traffic. This dissertation focuses on proposing novel solutions for this problem. The design challenge stems from the nature of multicast traffic, i.e., a multicast packet typically has multiple destinations. On the one hand, this nature makes queueing and scheduling of multicast traffic much more difficult than that of …

Introducing The Engineering Technology Programs To All Incoming Freshmen Engineering And Technology Students–The Result Is Better For All, Gary Crossman, Anthony Dean

Engineering Technology Faculty Publications

The Department of Engineering Technology at Old Dominion University participates in a freshman engineering course sequence, along with four engineering departments in the Batten College of Engineering and Technology. The two course sequence, Exploring Engineering and Technology I and II, involve the five departments in teaching at least one five week module in each of the two courses. Each department generally involves the students in a basic design project related to its discipline. Since the Department of Engineering Technology has three main programs – Civil, Electrical, and Mechanical – it has elected to divide its five week segment into three …

Atmospheric-Pressure Plasma Sources For Polymer Surface Modification, Shujun Yang

Electrical & Computer Engineering Theses & Dissertations

Plasma processing is widely used in the microelectronics industry for deposition of thin films. It is also used in etching of semiconductors, metals and organic materials such as photoresists. In addition, plasmas are widely used to modify material surfaces. Plasma surface modification can improve the surface adhesion of polymeric materials, which can be used as insulating layers in multilayer semiconductor structures. In deposition and etching, relatively a large amount of material is added to or removed from the surface. In plasma surface modification, only the surface layer is changed in composition or structure, and no significant amount of material is …

Mechanical Properties And Durability Of A Composite Material At Cryogenic Temperatures, Ray Walton Grenoble

Mechanical & Aerospace Engineering Theses & Dissertations

Several issues relevant to the use of a high-performance graphite-epoxy material in hydrogen storage tank applications have been examined. The tensile properties of IM7/977-2 were evaluated as a function of test temperature and thermal-mechanical load history. The temperature dependent coefficient of thermal expansion (CTE) of unidirectional specimens of the same material was measured between -200°C and 0°C. The effects of test temperature, mechanical loading, and damage state on the leak rate of hydrogen gas through IM7/977-2 laminates were evaluated using a novel test system. Finally, the mechanical properties of several commercially available polymer films, which might prove useful as leak-resistant …

A Multilane Pipelined Architecture For Real Time Enhancement Of Color Video Streams, Adam Redd Livingston

Electrical & Computer Engineering Theses & Dissertations

Video stream enhancement is a key fixture in a wide variety of applications from video surveillance, automatic navigation, medical imagery, to facial/object recognition systems. When a video stream contains non-uniform lighting it can be difficult to obtain what is in the darker regions without over enhancing brighter regions. The Adaptive and Integrated Neighborhood Dependant Approach for Nonlinear Enhancement (AINDANE) algorithm combines a tunable nonlinear transfer function, convolution by a multi-scale Gaussian kernel, and tunable contrast enhancement to address this problem for a single image. Luminance values are tuned based on the global cumulative distribution function (CDF) of an image. Contrast …

Mobius: An Omnidirectional Robotic Platform And Software Architecture For Network Teleoperation, Samuel Aaron Miller

Electrical & Computer Engineering Theses & Dissertations

The following thesis presents the results of a project to develop and test an omnidirectional robotic system (hardware and software) at NASA Langley Research Center's Robotics and Intelligent Machines Lab. The impetus for the project was the unique capabilities of omnidirectional systems. Some of the many potential benefits these systems have include improved material-handling capabilities in constrained environments (such as might be found in extraterrestrial manned habitats), efficient camera-based vehicle teleoperation, and simplified route planning for autonomous robot operations.

The project's focus was to design, build, and test a system that used Mecanum wheels to achieve omnidirectional motion. In addition …

Crisis Management In Projects, Senol Nazikkol

Engineering Management & Systems Engineering Theses & Dissertations

The objective of this investigation is to identify the processes, benefits and important tools of crisis management in projects. Crisis management is a system that helps managers to prevent and overcome crises. In this research, a general review about crisis, crisis management processes and tools are discussed. The research was done by using the information in the literature and expert judgment. This paper can be used by academics as a foundation for further research and development in the area of crisis management in projects. Managers of projects can use this study for improving their projects and project-based organizations' crisis management …

Information Visualization Methods And Techniques Using Web Services, Kevin Dupigny

Computational Modeling & Simulation Engineering Theses & Dissertations

Data, even in small amounts, can be difficult to interpret quickly and efficiently. Data domains are continually expanding and making this data available and usable in collaborative data environment is a challenge that was not addressed by legacy systems. Such a framework would make the existence of a global information sharing system feasible. Visualizing this complex dataset presents a complex task for current static interface solutions. A flexible layered service oriented model is presented in this work to approach this challenge. The visual scope of human perception is largely untapped by today's data visualization applications. Human mental processes are adept …

Process And Product Optimization Techniques - A Comparative Analysis Using Optimization Of Surface Roughness, Amol Suresh Sonje

Mechanical & Aerospace Engineering Theses & Dissertations

Robust design improves the fundamental function of the product or process considering noise factors in DOE. G. Taguchi has made significant advances in the use of experimental design. Taguchi methods are criticized on the basis of failure to deal with interactions, use of SIN ratio and lack of sequential nature of investigation. Response Surface Methodology deals with designing models that represents response in terms of various factors affecting it. Optimization of surface finish is achieved using both Taguchi Methods and Response Surface Methodology.

Dual response approach is a combination of Taguchi methods and RSM techniques in which primary response is …

Computational Aerodynamics Study Of Ahmed Body Car Model, Rajat Trehan

Mechanical & Aerospace Engineering Theses & Dissertations

Vehicle Aerodynamics has been the focus of study by researchers for centuries. This interest can be owed to increasing demand on fuel efficiency, vehicle top speed and acceleration performance. Interior aerodynamics, such as engine cooling, air conditioning, wind noise, stability, and cross wind sensitivity play key role in customer satisfaction. Hence a complete understanding of flow around the vehicle is prerequisite to achieve any of the above parameters. Aerodynamic development of motor vehicle is expensive. Much capital must be invested in test facilities such as wind tunnels and climate tunnels. The models are costly and at the beginning of a …

Strategy For Product Reusability Based On Technical And Economic Model, Srikanth Uppuluri

Mechanical & Aerospace Engineering Theses & Dissertations

Reusing old components is considered the most profitable End-of-Life strategy in the modern day scenario of sustainable manufacturing. Though there is increasing pressure on the product designers worldwide to make reuse possible, the functionality of the products and the economic feasibility have been the main considerations for manufacturers in evaluating the reuse strategy. The quality level of the used product and mainly the economic aspect of disassembling the product have been the main uncertainties confronting the industries to move towards the product recovery strategies like reuse and disassembly. The profitability factor in designing and implementing the technology for disassembly of …

A Component Based Formal Ontology Model, A Method For Evaluating Such A Model, And The Results Of An Application Of That Method, Charles Tumitsa

Computational Modeling & Simulation Engineering Theses & Dissertations

For systems to truly communicate effectively, more than just data interchange is necessary. The systems must achieve conceptual interoperability, which implies communicating with understanding.

The LCIM (Levels of Conceptual Interoperability Model) describes a number of levels of interoperability, each of which shows systems with an increased amount of conceptual understanding of the other systems they are communicating with. The lowest levels of this model, technical and syntactic interoperability, are achieved (and there are many existing examples) via data exchange in a number of different ways. Research has shown, however, that to attain higher levels of conceptual understanding, that there must …

Reversing Ticket Based Probing (Rtbp) Routing For Manet, Turgut Yucel

Electrical & Computer Engineering Theses & Dissertations

The delay-constrained maximum-bandwidth routing problem in MANET (Mobile Ad hoc Networks) is to find the maximum bandwidth path which satisfies a given delay constraint. The research challenge for this problem is that the networking information used for routing may be imprecise. The Ticket-Based Probing (TBP) routing algorithm provides a heuristic approach by using two types of ticket. In this thesis a Reversing Ticket-based Probing (RTBP) routing algorithm is proposed. The RTBP has two novel features compared to the original ticket based probing algorithms. The first feature is using just one type ticket, instead of two types of ticket. RTBP generates …

Passive And Active Nonlinear Control Of Ship Roll Motions Using U-Tube Tanks, Thongchai Phairoh

Mechanical & Aerospace Engineering Theses & Dissertations

A U-tube water tank is first designed to roll a ship floating on still water. The 6-degree of freedom (DOF) dynamic model of U-tube tank is derived and the effects of its parameters on ship roll motion are studied. Numerical simulations show that the U-tube tank is an effective stimulator to roll the ship on still water. For a rolling ship, the U-tube tank can be used as a damper to reduce ship roll motion quickly.

Active control of ship roll motion with a proportional and derivative (PD) controller, linear quadratic regulator (LQR), generalized predictive control (GPC), and deadbeat predictive …

Whole Word Phonetic Displays For Speech Articulation Training, Fansheng Meng

Electrical & Computer Engineering Theses & Dissertations

The main objective of this dissertation is to investigate and develop speech recognition technologies for speech training for people with hearing impairments. During the course of this work, a computer aided speech training system for articulation speech training was also designed and implemented. The speech training system places emphasis on displays to improve children's pronunciation of isolated Consonant-Vowel-Consonant (CVC) words, with displays at both the phonetic level and whole word level. This dissertation presents two hybrid methods for combining Hidden Markov Models (HMMs) and Neural Networks (NNs) for speech recognition. The first method uses NN outputs as posterior probability estimators …

Fixture Design For Load Measurement In Friction Stir Welding, Shekhar S. Kulkarni

Mechanical & Aerospace Engineering Theses & Dissertations

In the Friction Stir Welding Process a vertical force is required for plunging the pin or probe of the tool into the workpiece specimen material, and maintaining contact between the shoulder and the substrate. In addition to the vertical force, Friction Stir Welding Process also involves a horizontal force, which is instrumental for the advancement of the tool as the weld progresses. The essential objective of the thesis was to design, manufacture and test a fixture that can be utilized to measure the vertical force as well as the horizontal force. The designing of the fixture was concerned with various …

A Non-Linear Technique For The Enhancement Of Extremely Non-Uniform Lighting Images, Ender Oguslu

Electrical & Computer Engineering Theses & Dissertations

At night scenes, either the low intensity areas that are under poor light or the high intensity areas that are overexposed cannot be clearly seen. Various image processing techniques have been developed to recover the meaningful information under extremely low lighting conditions. Among these, the algorithms based on integrated neighborhood dependency of pixel characteristics and based on the illuminance reflectance model perform well for improving the visual quality of digital images captured under nonuniform and extremely low lighting conditions. Although these techniques perform well in low lighting conditions, they cannot perform well in overexposed regions under dark environments such as …

Boundary Interference Assessment And Correction For Open Jet Wind Tunnels Using Panel Methods, Wael Ahmed Mokhtar

Mechanical & Aerospace Engineering Theses & Dissertations

The presence of nearby boundaries in a wind tunnel can lead to aerodynamic measurements on a model in the wind tunnel that differ from those that would be made when the boundaries of the moving fluid were infinitely far away. The differences, referred to as boundary interference or wall interference, can be quite large, such as when testing aircraft models developing high lift forces, or whose wingspan is a large fraction of the wind tunnel width, or high drag models whose frontal area is a large fraction of the tunnel cross section. Correction techniques for closed test section (solid walled) …

A Comparative Analysis Of Air-To-Ground Engagement Outcomes In The Joint Warfare System (Jwars) And The Jwars-Joint Semi-Automated Forces Federation, Melissa Anne St. Peter

Computational Modeling & Simulation Engineering Theses & Dissertations

Multi-resolution modeling is the process by which a single model is created by connecting multiple individual models to describe phenomena at different levels of resolution [1]. "When we change resolutions, replacing a detailed model by a more aggregate one, we must ask whether results are 'consistent'" [2].

There are many methods of determining if the results of two simulations are 'consistent'. However, they are very entailed and require a detailed understanding of the individual models including their functionality, algorithms, and inner workings. A straight forward and rapid way of assessing potential inconsistencies is through a statistical comparison of the model …

A Markovian Statistical Analysis Of Single-Event Upsets On Closed-Loop Flight Control Systems, Anushka Vishnukumar Lakdawaia

Electrical & Computer Engineering Theses & Dissertations

The operation of aircrafts depend heavily on closed-loop digital flight control systems which can be disrupted or upset by errant neutrons at aircraft flight altitudes. These upsets, called single-event upsets, range from data corruption to short circuits which can potentially cause physical damage to digital devices and unexpected behaviors in flight controls. Experiments conducted at the Los Alamos Neutron Science Center consisted of irradiating an experimental flight control computer (FCC) architecture with a high intensity neutron beam while the FCC controlled a simulation of a Boeing 737. It was postulated that the upset statistics on the FCC could be fitted …

The Analytic Hierarchy & The Analytic Network Processes In Multicriteria Decision Making: A Comparative Study, Ali K. Taslicali

Engineering Management & Systems Engineering Theses & Dissertations

The objective of this investigation is to identify the critical benefits and factors of decision making models in a changing technological environment. Decision making models are helping tools for the managers or decision makers to make future plans by using qualitative or quantitative data. In this research, a general idea about decision making models and, comparison between the two important models, the Analytical Hierarchy Process (AHP) and the Analytical Network Process (ANP), are introduced. The research was done by using the information in the literature and expert judgment. This paper can be used by academics as a foundation for further …