Digital Commons Network^™

Systematic Parameter Analysis For Selective Laser Melting (Slm) Of Silver-Based Materials., Harald Rieper

Electronic Theses and Dissertations

Selective Laser Melting (SLM) is a growing technology for the additive manufacturing of parts and structures. Based on a powder layer technique, a laser locally melts the powder and forms new structures. [1] In this approach, silver-based alloy powders will be used. The processing of this kind of material is considered difficult compared to other powder materials such as mild steels or tool steels. Silver powder is a highly reflecting material and has excellent thermal conductivity. Both properties make it difficult to process using Selective Laser Melting. Due to its high price, industries use silver parts as economically as possible …

Modeling, Design, Packaging And Experimental Analysis Of Liquid-Phase Shear-Horizontal Surface Acoustic Wave, Thomas B. Pollard

Electronic Theses and Dissertations

Recent advances in microbiology, computational capabilities, and microelectromechanical-system fabrication techniques permit modeling, design, and fabrication of low-cost, miniature, sensitive and selective liquid-phase sensors and labon- a-chip systems. Such devices are expected to replace expensive, time-consuming, and bulky laboratory-based testing equipment. Potential applications for devices include: fluid characterization for material science and industry; chemical analysis in medicine and pharmacology; study of biological processes; food analysis; chemical kinetics analysis; and environmental monitoring. When combined with liquid-phase packaging, sensors based on surface-acoustic-wave (SAW) technology are considered strong candidates. For this reason such devices are focused on in this work; emphasis placed on device …

Characterization Of The Elastic, Piezoelectric, And Dielectric Properties Of Langatate At High Temperatures Up To 900 ◦C, Peter Mark Davulis

Electronic Theses and Dissertations

The acoustic wave constants of the piezoelectric crystal langatate (LGT, La3Ga5.5Ta0.5O14) are characterized up to 900 ◦C for the first time in this work, targeting the development of high-temperature acoustic wave (AW) devices. There is a pressing need for sensors and frequency control systems that operate at high temperature, above 200 ◦C, and in harsh environments, with applications found in the industrial process control, automotive, aerospace, and power generation industries and in gas and petroleum exploration. Surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices, using piezoelectric crystals such as LGT, have the capability to provide the desired high-temperature …

Geometric Modeling Of Non-Rigid 3d Shapes : Theory And Application To Object Recognition., Mostafa Abdelrahman

Electronic Theses and Dissertations

One of the major goals of computer vision is the development of flexible and efficient methods for shape representation. This is true, especially for non-rigid 3D shapes where a great variety of shapes are produced as a result of deformations of a non-rigid object. Modeling these non-rigid shapes is a very challenging problem. Being able to analyze the properties of such shapes and describe their behavior is the key issue in research. Also, considering photometric features can play an important role in many shape analysis applications, such as shape matching and correspondence because it contains rich information about the visual …

Face Recognition Using Statistical Adapted Local Binary Patterns., Abdallah Abd-Elghafar Mohamed

Electronic Theses and Dissertations

Biometrics is the study of methods of recognizing humans based on their behavioral and physical characteristics or traits. Face recognition is one of the biometric modalities that received a great amount of attention from many researchers during the past few decades because of its potential applications in a variety of security domains. Face recognition however is not only concerned with recognizing human faces, but also with recognizing faces of non-biological entities or avatars. Fortunately, the need for secure and affordable virtual worlds is attracting the attention of many researchers who seek to find fast, automatic and reliable ways to identify …

Face Recognition In The Wild., Mostafa A. Farag

Electronic Theses and Dissertations

Research in face recognition deals with problems related to Age, Pose, Illumination and Expression (A-PIE), and seeks approaches that are invariant to these factors. Video images add a temporal aspect to the image acquisition process. Another degree of complexity, above and beyond A-PIE recognition, occurs when multiple pieces of information are known about people, which may be distorted, partially occluded, or disguised, and when the imaging conditions are totally unorthodox! A-PIE recognition in these circumstances becomes really “wild” and therefore, Face Recognition in the Wild has emerged as a field of research in the past few years. Its main purpose …

Linking Corporate Strategy To Operations : A Critical Review Of Prof. Kaplan’S Theories And The Development Of A Best-Practice Approach., Alexander Bogner

Electronic Theses and Dissertations

The rising speed of change in global frameworks drives international companies into a non-stop changing organization with the need of generating optimal revenues under changing conditions. Regarding to the need to be a flexible and competitive organization the value of a vision and a perfectly streamed strategy to this vision becomes a main success factor for global business. The trend for the need of development of a clear and constant strategy is equally rising with the trend of globalization and intercontinental business companies and therefor the business of strategy consulting rises constantly from the late 1990. Most of the strategy …

Charge Collection And Surface Recombination Effects In Organic Bulk Heterojunction Solar Cells., Buddika Ka. Abeyweera 1980-

Electronic Theses and Dissertations

Charge transfer and charge extraction mechanisms are two prevalent issues in the growing field of organic solar cells. Due to their complexity in nature, new methods need to be involved in addressing the fundamental properties associated with organic polymer solar cells. This dissertation has focused on developing a new method to estimate the charge collection lengths and surface recombination lengths of organic polymer solar cells. Photocurrent spectra have been analyzed systematically to observe the dependence on thickness of the active material. A red shift of the peak of the normalized photocurrent with respect to the device thickness has been further …

An Inter-Domain Supervision Framework For Collaborative Clustering Of Data With Mixed Types., Artur Abdullin

Electronic Theses and Dissertations

We propose an Inter-Domain Supervision (IDS) clustering framework to discover clusters within diverse data formats, mixed-type attributes and different sources of data. This approach can be used for combined clustering of diverse representations of the data, in particular where data comes from different sources, some of which may be unreliable or uncertain, or for exploiting optional external concept set labels to guide the clustering of the main data set in its original domain. We additionally take into account possible incompatibilities in the data via an automated inter-domain compatibility analysis. Our results in clustering real data sets with mixed numerical, categorical, …

Pulsatile Flow Does Not Improve Efficacy In Ex Vivo Lung Perfusion., Keith A. Zoeller

Electronic Theses and Dissertations

Introduction Ex vivo lung perfusion (EVLP) has the potential to increase the donor pool for lung transplantation by facilitating extended evaluation of marginal organs. Current methodology employs continuous flow pumps for perfusion. In vivo, continuous flow has been shown to increase pulmonary vascular resistance (PVR). Thus, pulsatile flow EVLP may reduce PVR and improve organ preservation by providing physiologic flow morphology. Methods Lung blocks harvested from male, Yorkshire pigs were allocated into continuous (CF, n=3) and pulsatile flow (PF, n=4) groups. Lungs were ventilated at 4-5 mL/kg, 30% FiO2 and perfused with an acellular, albumin-based solution corrected for osmolarity, acid/base …

Multi-Physical Study Of Mems Resonators And Oscillators, Xiaobo Guo

Electronic Theses and Dissertations

First, this research presents experimental and theoretical investigation of the response of micro scale dual-plate thermal-piezoresistive resonators (TPR) and self-sustained oscillators (TPO) to different gases and pressures. It is demonstrated that the resonant frequency of such devices follows particular trends in response to the changes in the surrounding gas and its pressure. A mathematical model has been derived to explain the damping dependent frequency shift characteristic of TPO. The solution of the model indicates that the stiffness of the actuator beam decreases as the value of damping coefficient drops at lower gas density caused by the change in the gas …

Dexterous Hexrotor Uav Platform, Guangying Jiang

Electronic Theses and Dissertations

Mobile manipulation is a hot area of study in robotics as it unites the two classes of robots: locomotors and manipulators. An emerging niche in the field of mobile manipulation is aerial mobile manipulation. Although there has been a fair amount of study of free-flying satellites with graspers, the more recent trend has been to outfit UAVs with graspers to assist various manipulation tasks. While this recent work has yielded impressive results, it is hampered by a lack of appropriate testbeds for aerial mobile manipulation, similar to the state of ground-based mobile manipulation a decade ago. Typical helicopters or quadrotors …

Meta-Routing: Synergistic Merging Of Message Routing And Link Maintenance, Mustafa A. Ayad

Electronic Theses and Dissertations

The maintenance of network connectivity is essential for effective and efficient mobile team operations. Achieving robust mobile ad hoc networks (MANETs) connectivity requires a capable link maintenance mechanism especially if the network experiences expected intermittent connectivity due to a hostile environment. One applicable example of such network scenarios is multi-robot exploration for urban search and rescue (USAR). With the proliferation of these robotic networks, communication problems such as the link maintenance problem are subject to be raised quickly. Although various routing protocols for wireless ad hoc networks have been proposed, they solve the problems of message routing and link maintenance …

High Data Rate Coherent Optical Ofdm System For Long-Haul Transmission, Khaled Alatawi

Electronic Theses and Dissertations

The growth in internet traffic has driven the increase in demand for bandwidth and high data rates. Optical Orthogonal Frequency Division Multiplexing is considered as a promising technology to satisfy the increased demand for bandwidth in broadband services. Optical OFDM received a great attention after proposing it as a modulation technique for the long-haul transmission in both direct and coherent detection. However, Coherent Optical OFDM (CO-OFDM) is the next generation technology for the optical communications, since it integrates the advantages of both coherent systems and OFDM systems. It has the ability to overcome many optical fiber restrictions such as chromatic …

Integration Of Oofdm With Rof For High Data Rates Long-Haul Optical Communications, Fahad Almasoudi

Electronic Theses and Dissertations

One of the advanced technologies in optical fiber communication systems that support efficient convergence of wireless and optical access network structure is Radio over Fiber (RoF). In RoF, light is modulated by using a radio signal and sent over an optical fiber link to simplify wireless access. The demand for high-speed wireless communications is increasing rapidly. To increase the capacity and bandwidth of the optical fiber communication system a Wavelength-Division Multiplexing (WDM) is used. In WDM, multiple optical carrier signals are multiplexed and transmitted over one optical fiber.

Optical Orthogonal Frequency Division Multiplexing (OOFDM) technology commits to be a fundamental …

Power Fluctuations Smoothing And Regulations In Wind Turbine Generator Systems, Hamed Babazadehrokni

Electronic Theses and Dissertations

Wind is one of the most popular renewable energy sources and it has the potential to become the biggest energy source in future. Since the wind does not always blow constantly, the output wind power is not constant which may make some problem for the power grid. According to the grid code which is set by independent system operator, ISO, wind turbine generator systems need to follow some standards such as the predetermined acceptable power fluctuations.

In order to smooth the output powers, the energy storage system and some power electronics modules are employed. The utilized power electronics modules in …

Development Of A Computational Approach To Assess Hip Fracture And Repair: Considerations Of Intersubject And Surgical Alignment Variability, Azhar Ali

Electronic Theses and Dissertations

Hip fracture remains a major public health concern due to the significant number of occurrences and mortality rates. Intertrochanteric fractures are the most common type of fracture and are typically caused by a fall. Intramedullary osteosynthesis is a common surgical practice to repair intertrochanteric fractures, but revisions are often required. The work presented in this thesis aims to improve the realism and fidelity of computational models of hip fracture, which can be an effective alternative to costly and labor-intensive clinical in-vivo and experimental in-vitro testing. Intersubject variability is inherently present in anatomy and material relations. Statistical shape and intensity models …

Human Action Recognition Via Fused Kinematic Structure And Surface Representation, Salah R. Althloothi

Electronic Theses and Dissertations

Human action recognition from visual data has remained a challenging problem in the field of computer vision and pattern recognition. This dissertation introduces a new methodology for human action recognition using motion features extracted from kinematic structure, and shape features extracted from surface representation of human body. Motion features are used to provide sufficient information about human movement, whereas shape features are used to describe the structure of silhouette. These features are fused at the kernel level using Multikernel Learning (MKL) technique to enhance the overall performance of human action recognition. In fact, there are advantages in using multiple types …

Estudy Of Ber Performance In Passive Optical Networks With Different Modulation Techniques, Ayoob Alateeq

Electronic Theses and Dissertations

The amazing growth in the usage of the broadband services has motivated a number of the services' providers to find drastic solutions. The percentage of broadband subscribers has increased from 5.3% of the world population in 2007 to 8.5% of the population in 2011. The increase in the number of subcarriers and a high bandwidth requirement are two motivations to demonstrate the broadband service provision. As a promised demonstration of the broadband provision, professionals use optical fiber to account for the present and the future broadband demand.

Power consumption and bandwidth capacity, which the optical fiber has offered, are two …

Vision-Based 3d Human Motion Analysis For Fall Detection And Bed-Exiting, Xiaoxiao Dai

Electronic Theses and Dissertations

Fall is one of the most dangerous and costly accidents that threaten health of elderly people, and a large portion of falls occurs when a patient is trying to exit a bed. This thesis proposes two vision-based approaches for general fall detection and bed-exiting detection for elderly people, respectively. The Kinect sensor is chosen as the major monitoring device.

The first approach exploits the Kinect sensor with its Windows SDK to detect fall activities. The recorded spatial coordinates of the human body joints from Kinect's 3D skeletal view are processed to extract posture features. Then the principle component analysis and …

Design, Optimization, And Testing Of A Cross-Flow Tidal Turbine, Megan Colleen Swanger

Electronic Theses and Dissertations

This thesis is a summary of testing conducted with a Darrieus style cross-flow tidal turbine. Many locations around the world have locations suitable for tidal turbine energy, including the Cobscook Bay in Eastport, Maine. Cross-flow turbines are likely to have a smaller impact on the environment compared to axial flow turbines due to their operation at lower tip speed ratios. Since very little experimental data is available presently for cross-flow turbines, this study provides an expansive set of performance data for two NACA series blade profiles of the same chord length. One blade profile was used in two different orientations …

Computational Biomechanical Modeling Of The Human Knee During Kneeling, Tariq R. Abo-Alhol

Electronic Theses and Dissertations

Total knee replacement benefits patients who suffer from severe knee pain or joint stiffness and other joint related illnesses that limit everyday activities. There has been an increase in the number of procedures performed each year and a need to evaluate the performance of these implants during specialized activities such as kneeling. Most computational studies lack insight into inter-patient variability and the results do not apply to large population. This study developed: (1) three-dimensional explicit finite element (FE) models to investigate natural and implanted knee joint kinematics and bone strain and (2) a platform to enable population-based evaluation by combining …

The Assignment Problem With Dependent Costs., Ghazal Tariri

Electronic Theses and Dissertations

Assigning workers, each with their own skill set, to tasks which demand different skills in an efficient manner is a challenging problem that often requires workers to receive additional training. The training of workers is very costly with Training Magazine’s Annual Industry Report stating 58.5 billion dollars were spent in 2007 on employee training in the United States. Therefore assigning workers to tasks in such a way as to minimize the overall training costs is an important problem in many organizations. In this research, the assignment problem with dependent cost is considered, i.e. the training cost associated with assigning a …

Design And Development Of An Integrated Mobile Robot System For Use In Simple Formations, Christopher D. Brune

Electronic Theses and Dissertations

In recent years, formation control of autonomous unmanned vehicles has become an active area of research with its many broad applications in areas such as transportation and surveillance. The work presented in this thesis involves the design and implementation of small unmanned ground vehicles to be used in leader-follower formations. This mechatronics project involves breadth in areas of mechanical, electrical, and computer engineering design. A vehicle with a unicycle-type drive mechanism is designed in 3D CAD software and manufactured using 3D printing capabilities. The vehicle is then modeled using the unicycle kinematic equations of motion and simulated in MATLAB/Simulink. Simple …

An Efficient Navigation-Control System For Small Unmanned Aircraft, Jonathan Alejandro Girwar-Nath

Electronic Theses and Dissertations

Unmanned Aerial Vehicles have been research in the past decade for a broad range of tasks and application domains such as search and rescue, reconnaissance, traffic control, pipe line inspections, surveillance, border patrol, and communication bridging.

This work describes the design and implementation of a lightweight Commercial-Off-The-Shelf (COTS) semi-autonomous Fixed-Wing Unmanned Aerial Vehicle (UAV). Presented here is a methodology for System Identification utilizing the Box-Jenkins model estimator on recorded flight data to characterize the system and develop a mathematical model of the aircraft. Additionally, a novel microprocessor, the XMOS, is utilized to navigate and maneuver the aircraft utilizing a PD …

Evaluation Of Novel High-Density Emg Feedback Parameters On The Spatial Distribution Of Trapezius Muscle Activity, Brecca M. Gaffney

Electronic Theses and Dissertations

Each year, 17.9% of adults working in a computer-dominated work environment develop an episode of chronic neck and shoulder pain. An effective treatment method for chronic pain is postural correction through therapist. The understanding of the relation between cervicoscapular posture and trapezius muscle activity is not fully understood because the anatomy of the scapula is not accessible for direct observation. Until recently, the spatial distribution of trapezius muscle activity could not be measured due to the limitation in size of detection zone in traditional bipolar electrodes. The primary goal of postural correction when treating cases of chronic neck and shoulder …

Using Discrete Event Simulation To Improve The Patient Care Process In The Emergency Department Of A Rural Kentucky Hospital., Molly Cassaro Jones

Electronic Theses and Dissertations

The patient care process of a rural Kentucky hospital is a complex process that must be flexible in order to deal with a large variety of patient needs and a fluctuating patient volume where all patients are unscheduled. A simulation model of an average month in the emergency department was built using the Arena Simulation package. Methods for creating a simulation using Arena are included in this work. Statistics were generated from a number of different sources to create an accurate representation of the model. The Hospital reporting shows a need to improve on two quality measures being tracked, the …

An Investigation Of The Impact Of Requirements Engineering Skills On Project Success, Cynthia Atkins

Electronic Theses and Dissertations

A survey of project managers and requirements engineers was conducted to determine what skills, qualifications, and experiences were associated with project success. Survey results indicated that projects using Joint Application Development (JAD) sessions, use cases, and prototypes to engineer requirements were most successful. Other indicators of project success, according to participants, included an adequate allotment of time for requirements engineering—at least 15% of a project's time—and the use of project managers and requirements engineers with professional work experience. In particular, data indicated that Project Managers with at least five years of experience in Information Technology resulted in more successful projects.

Lc Oscillator Chirp Generator For Ladar Applications, Joseph Richard Grace Iii

Electronic Theses and Dissertations

The design, layout, simulation, and testing of a signal generator integrated circuit (IC) intended to create a frequency modulated chirp signal used in Laser Assisted Detection and Ranging (LADAR) systems are described. LADAR systems function by illuminating a target with a laser beam and measuring the properties of the reflected signal. Applications include range finding, collision avoidance, terrain mapping, and facial recognition. The development and improvement of LADAR IC design can lead to miniaturized LADAR-on-chip systems that could significantly improve the usability and applications of said systems. Two designs, a fixed frequency oscillator bank (FFOB) and a voltage controlled oscillator …

Towards A Filmic Look And Feel In Real Time Computer Graphics, Sherief Farouk

Electronic Theses and Dissertations

Film footage has a distinct look and feel that audience can instantly recognize, making its replication desirable for computer generated graphics. This thesis presents methods capable of replicating significant portions of the film look and feel while being able to fit within the constraints imposed by real-time computer generated graphics on consumer hardware.