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Articles 101971 - 102000 of 198087

Full-Text Articles in Engineering

Practical Robust Geotechnical Design- Methodology And Applications, Sara Khoshnevisan Dec 2015

Practical Robust Geotechnical Design- Methodology And Applications, Sara Khoshnevisan

All Dissertations

This dissertation advances the robust geotechnical design methodology by offering improvements, which makes it more efficient and practical for the design of geotechnical systems. Robust geotechnical design (RGD) methodology seeks an optimal design, which is insensitive to, or robust against, the variation in the uncertain input parameters (called “noise factors”) by only adjusting the easy to control parameters (called “design parameters”). The main goal of robust design is to consider safety, cost and robustness simultaneously. Because the cost and the robustness are conflicting objectives, the multi-objective optimization that considers these two objectives while enforcing the safety constraint yields not a …


Nursing Interruption Dynamics: The Impact Of Work System Factors, Yushi Yang Dec 2015

Nursing Interruption Dynamics: The Impact Of Work System Factors, Yushi Yang

All Dissertations

Interruptions occur frequently in healthcare work systems. Hands-free Communication Devices (HCDs) were implemented in healthcare work systems to support the interruption process. However, from a sociotechnical systems perspective, HCDs may introduce new complications and unintended consequences to the work system. Research gaps exist in investigating the complexity of HCD interruptions in the real-world context. This dissertation aims to understand HCD interruption dynamics in the nursing work systems, using qualitative research methods. The first study examined the major differences between face-to-face and HCD-mediated interruptions, based on 30 hours of field observations in the acute care setting. Three major differences included: (1) …


An Investigation Of The Efficiency Of Synergistic Multicultural Teams, Melissa Dorlette Paul Dec 2015

An Investigation Of The Efficiency Of Synergistic Multicultural Teams, Melissa Dorlette Paul

All Dissertations

The current globalized environment has increased the prevalence of multicultural teams in the workplace. While much research has focused on the advantages of such teams, the challenges companies should anticipate when using them has not received as much attention. These difficulties, specifically communication and trust, need to be considered to ensure that the company remains competitive in an economy driven by growing client expectations. In addition, companies often have to meet tight delivery schedules in order to survive, an expectation which adds strain on production teams. Efforts to address these issues have ranged widely, with some researchers suggesting cultural awareness …


Robust Model Development For Evaluation Of Existing Structures, Saurabh Prabhu Dec 2015

Robust Model Development For Evaluation Of Existing Structures, Saurabh Prabhu

All Dissertations

In the context of scientific computing, validation aims to determine the worthiness of a model in supporting critical decision making. This determination must occur given the imperfections in the mathematical representation resulting from the unavoidable idealizations of physics phenomena. Uncertainty in parameter values furthers the validation problems due to the inevitable lack of information about material properties, boundary conditions, loads, etc. which must be taken into account in making predictions about structural response. The determination of worthiness then becomes assessing whether an unavoidably imperfect mathematical model, subjected to poorly known input parameters, can predict sufficiently well in its intended purpose. …


Proportioning And Properties Of Ultra-High Performance Concrete Mixtures For Application In Shear Keys Of Precast Concrete Bridges, Zhengqi Li Dec 2015

Proportioning And Properties Of Ultra-High Performance Concrete Mixtures For Application In Shear Keys Of Precast Concrete Bridges, Zhengqi Li

All Dissertations

Ultra-high performance concrete (UHPC) is defined as a cementitious based composite material with compressive strengths above 150 MPa, pre-and post-cracking tensile strengths above 5 MPa, and enhanced durability. To achieve desired properties, UHPC is typically produced with low water-cementitious materials (w/cm) ratio (i.e. w/cm < 0.25), high cementitious materials content (i.e. >1000 kg/m3), high quality aggregate, high dosage of high-range water reducing admixture (HRWRA) and reinforcing fibers. UHPC has distinct advantages in applications where narrow formwork and dense reinforcement are inevitable, high compressive strength concrete material is required and the surrounding environment is aggressive. The construction of shear keys in precast bridges is one of the important …


Designing Optical Properties In Infrared Glass, Benn Gleason Dec 2015

Designing Optical Properties In Infrared Glass, Benn Gleason

All Dissertations

Chalcogenide glasses (ChGs) are well-known for their attractive optical properties, such as high refractive index and transparency in across infrared wavelengths. ChGs also possess the ability to compositionally tune properties such as the refractive index, the thermo-optic coefficient, and other non-optical properties. Chalcogenide glasses with compositionally tailored physical and optical properties will provide optical designers with new materials necessary to create novel infrared imaging systems requiring new or expanded functionality. This dissertation has evaluated the relationship between glass composition, the resulting atomic structure, and resulting optical and thermo-optical properties, with specific focus on the infrared refractive index and the thermo-optic …


Optimization Of Pyrochlore Catalysts For The Dry Reforming Of Methane, Felipe Polo Garzon Dec 2015

Optimization Of Pyrochlore Catalysts For The Dry Reforming Of Methane, Felipe Polo Garzon

All Dissertations

The conversion of methane into syngas (a mixture of CO and H2), which can be further converted into a variety of chemicals and particularly liquid fuels, is of growing importance given recent increases in methane production world-wide. Furthermore, since using CO2 as the co-feed offers many environmental advantages, dry reforming of methane (DRM, CH4 + CO2 ⇌ 2CO + 2H2) has received renewed attention. In recent years, experimentalists have shown that the Rh-substituted lanthanum zirconate pyrochlore (LRhZ) material is catalytically active for DRM, exhibits long-term thermal stability and resists deactivation; however, previous to this doctoral work, a detailed understanding of …


A Laminated Ring On Elastic Foundation Model With Application To Analysis Of Tire-Road Contact, Chunjian Wang Dec 2015

A Laminated Ring On Elastic Foundation Model With Application To Analysis Of Tire-Road Contact, Chunjian Wang

All Dissertations

A deformable Ring on Elastic Foundation (REF) model has been widely used for modeling rotating structures such as gears, bearings and tires. This dissertation extends the existing work with three main contributions focusing on applications to tires: 1) The elastic foundation is endowed with unilateral stiffness, which leads to a nonlinear deformation dependent stiffness typical of some non-pneumatic tires; 2) The model of the deformable ring is extended from simple Timoshenko rings to a laminated orthotropic ring model, with bending, shear stiffness and extensibility in the internal layer, and transverse stiffness in the external layer; 3) Facilitated by the laminated …


Integrated Coherent Combining Of Angled-Grating Broad-Area Lasers: Design, Fabrication And Characterization, Yunsong Zhao Dec 2015

Integrated Coherent Combining Of Angled-Grating Broad-Area Lasers: Design, Fabrication And Characterization, Yunsong Zhao

All Dissertations

In this thesis, we proposed, fabricated and demonstrated the coherent beam combining of angled-grating broad-area lasers. We have obtained the simultaneous coherent beam combining and single transverse mode operation completely on chip without any external phase control/components. Since the single transverse mode is the key to obtain diffraction-limit beam quality and high brightness, the proposed design is a good candidate for high power and high brightness applications. In the proposed coherently combined laser array, we use the angled-grating broad-area laser as the building block and overlap the adjacent emitters at one facet. The overlapped region becomes a 2D coupling region. …


Configuration Management In Manufacturing And Assembly: Case Study And Enabler Development, Keith Phelan Dec 2015

Configuration Management In Manufacturing And Assembly: Case Study And Enabler Development, Keith Phelan

All Dissertations

The overall goal of this research is to improve the product configuration change management process. The increase in the demand for highly customizable products has led to many manufacturers using mass customization to meet the constantly changing demands of a wide consumer base. However, effectively managing the configurations can be difficult, especially in large manufacturers or for complex products with a large number of possible configurations. This is largely due to a combination of the scope of the configuration management system and the difficulty in understanding how changes to one element of a configuration can propagate through the configuration system. …


Voxel-Level Absorbed Dose Calculations With A Deterministic Grid-Based Boltzmann Solver For Nuclear Medicine And The Clinical Value Of Voxel-Level Calculations, Justin Mikell Dec 2015

Voxel-Level Absorbed Dose Calculations With A Deterministic Grid-Based Boltzmann Solver For Nuclear Medicine And The Clinical Value Of Voxel-Level Calculations, Justin Mikell

Dissertations and Theses (Open Access)

Voxel-level absorbed dose (VLAD) is rarely calculated for nuclear medicine (NM) procedures involving unsealed sources or 90Y microspheres (YM). The current standard of practice for absorbed dose calculations in NM utilizes MIRD S-values, which 1) assume a uniform distribution in organs, 2) do not use patient specific geometry, and 3) lack a tumor model. VLADs overcome these limitations. One reason VLADs are not routinely performed is the difficulty in obtaining accurate absorbed doses in a clinically acceptable time. The deterministic grid-based Boltzmann solver (GBBS) was recently applied to radiation oncology where it was reported as fast and accurate for both …


An Automated Tool For High Resolution Visualization Applied To Transient Watershed Models, Noah Robert Taylor Dec 2015

An Automated Tool For High Resolution Visualization Applied To Transient Watershed Models, Noah Robert Taylor

Theses and Dissertations

Numeric hydrologic models can aid in water resource management by providing predictive simulations of water behavior. As computers become more advanced, the models developed also become more complex using more data to represent larger areas for forecasting hydrologic behavior. Unfortunately, as the simulations use more data, the output often becomes difficult to manage and share without investing time and effort into setting up server environments or decreasing the quality of the output to compensate for an efficient and effective user experience. A proposed solution to facilitate the accessibility of massive hydrologic model output is through the web-based visualization tool developed …


Configuration Scrubbing Architectures For High-Reliability Fpga Systems, Aaron Gerald Stoddard Dec 2015

Configuration Scrubbing Architectures For High-Reliability Fpga Systems, Aaron Gerald Stoddard

Theses and Dissertations

Field Programmable Gate Arrays (FPGAs) are being used more frequently in space applications because of their reconfigurability and intensive processing capabilities. FPGAs in environments like space are susceptible to ionizing radiation which can cause Single Event Upsets (SEUs) in the FPGA's configuration memory. These upsets may cause the programmed user design on the FPGA to deviate from its normal behavior. Space missions cannot afford to allow important data processing applications to become corrupted due to these radiation upsets.Configuration scrubbing is an upset mitigation technique that detects and corrects upsets in an FPGA's configuration memory. Configuration scrubbing periodically monitors an FPGA's …


Evaluating Long-Term Land Cover Changes For Malheur Lake, Oregon Using Envi And Arcgis, Ryan Joseph Woods Dec 2015

Evaluating Long-Term Land Cover Changes For Malheur Lake, Oregon Using Envi And Arcgis, Ryan Joseph Woods

Theses and Dissertations

Land cover change over time can be a useful indicator of variations in a watershed, such as the patterns of drought in an area. I present a case study using remotely sensed images from Landsat satellites for over a 30-year period to generate classifications representing land cover categories, which I use to quantify land cover change in the watershed areas that contribute to Malheur, Mud, and Harney Lakes. I selected images, about every 4 to 6 years from late June to late July, in an attempt to capture the peak vegetation growth and to avoid cloud cover. Complete coverage of …


Shaking Table Testing To Evaluate Effectiveness Of Prefabricated Vertical Drains For Liquefaction Mitigation, Caleb Robert Oakes Dec 2015

Shaking Table Testing To Evaluate Effectiveness Of Prefabricated Vertical Drains For Liquefaction Mitigation, Caleb Robert Oakes

Theses and Dissertations

This study was designed to evaluate the ability of vertical drains to prevent liquefaction and limit associated settlement. Drain performance was investigated using full-scale tests with vertical drains in liquefiable sand using a laminar shear box with acceleration time histories applied at the base. Performance of the sand box with drains in these tests was compared with performance of the sane box without drains in previous tests. The test data was also used to create case histories which can be used for further research and calibration of computer models. Although some investigations regarding vertical drains have been performed with centrifuge …


Numerical Analysis Of Passive Force On Skewed Bridge Abutments, Zifan Guo Dec 2015

Numerical Analysis Of Passive Force On Skewed Bridge Abutments, Zifan Guo

Theses and Dissertations

Accounting for seismic forces and thermal expansion in bridge design requires an accurate passive force-deflection relationship for the abutment wall. Current design codes make no allowance for skew effects on passive force; however, large scale field tests indicate that there is a substantial reduction in peak passive force as skew angle increases. A reduction in passive force also reduces the transverse shear resistance on the abutment. The purpose of this study is to validate three-dimensional model using PLAXIS 3D, against large scale test results performed at Brigham Young University and to develop a set of calibrated finite element models. The …


Long-Term Winter Inversion Properties In A Mountain Valley Of The Western United States And Implications On Air Quality, Shih-Yu (Simon) Wang, Lawrence E. Hipps, Oi-Yu Chung, Robert R. Gillies, Randy S. Martin Dec 2015

Long-Term Winter Inversion Properties In A Mountain Valley Of The Western United States And Implications On Air Quality, Shih-Yu (Simon) Wang, Lawrence E. Hipps, Oi-Yu Chung, Robert R. Gillies, Randy S. Martin

Civil and Environmental Engineering Faculty Publications

Because of the geography of a narrow valley and surrounding tall mountains, Cache Valley (located in northern Utah and southern Idaho) experiences frequent shallow temperature inversions that are both intense and persistent. Such temperature inversions have resulted in the worst air quality in the nation. In this paper, the historical properties of Cache Valley’s winter inversions are examined by using two meteorological stations with a difference in elevation of approximately 100 m and a horizontal distance apart of ~4.5 km. Differences in daily maximum air temperature between two stations were used to define the frequency and intensity of inversions. Despite …


In Vitro Multi-Scale Patient-Specific Modeling Of Hemodynamics In Stage 1 Norwood Palliation For The Treatment Of Single Ventricle Heart Disease, Tianqi Hang Dec 2015

In Vitro Multi-Scale Patient-Specific Modeling Of Hemodynamics In Stage 1 Norwood Palliation For The Treatment Of Single Ventricle Heart Disease, Tianqi Hang

All Dissertations

Hypoplastic left heart syndrome (HLHS) is a congenital heart defect in which the left ventricle is severely underdeveloped. The Norwood procedure is the first stage procedure to make an unrestrictive systemic blood flow and at the same time balance it with the pulmonary flow. This is done by constructing a neo-aorta using the pulmonary artery root and the autologous aorta, and then installing a shunt to the pulmonary artery. Variations of the Norwood surgery include the modified Blalock-Taussig (mBT) shunt, which diverts blood from the innominate artery to the pulmonary artery (PA), and the Right Ventricle Shunt (RVS), which diverts …


Electromechanical Modeling Of A Honeycomb Core Integrated Vibration Energy Converter With Increased Specific Power For Energy Harvesting Applications, Nataraj Chandrasekharan Dec 2015

Electromechanical Modeling Of A Honeycomb Core Integrated Vibration Energy Converter With Increased Specific Power For Energy Harvesting Applications, Nataraj Chandrasekharan

All Dissertations

Innovation in integrated circuit technology along with improved manufacturing processes has resulted in considerable reduction in power consumption of electromechanical devices. Majority of these devices are currently powered by batteries. However, the issues posed by batteries, including the need for frequent battery recharge/replacement has resulted in a compelling need for alternate energy to achieve self-sufficient device operation or to supplement battery power. Vibration based energy harvesting methods through piezoelectric transduction provides with a promising potential towards replacing or supplementing battery power source. However, current piezoelectric energy harvesters generate low specific power (power-to-weight ratio) when compared to batteries that the harvesters …


Electrospray Deposition Of Chalcogenide Glass Films For Gradient Refractive Index And Quantum Dot Incorporation, Spencer Novak Dec 2015

Electrospray Deposition Of Chalcogenide Glass Films For Gradient Refractive Index And Quantum Dot Incorporation, Spencer Novak

All Dissertations

Chalcogenide glasses (ChGs) are well-known for their optical properties, making them ideal candidates for emerging applications of mid-infrared microphotonic devices, such as lab-on-a-chip chemical sensing devices, which currently demand additional flexibility in processing and materials available to realize new device designs. Solution-derived processing of ChG films, initially developed in the 1980s by Chern and Lauks, has consisted mainly of spin-coating and offers unique advantages over the more traditional physical vapor deposition techniques. In the present effort, the nanoparticles of interest are luminescent quantum dots (QDs), which can be used as an on-chip source of light for a planar chemical sensing …


Developing Effective Ground And Space-Based Soil Moisture Sensing Techniques For Irrigating Cotton In Coastal Plain Soils, Xin Qiao Dec 2015

Developing Effective Ground And Space-Based Soil Moisture Sensing Techniques For Irrigating Cotton In Coastal Plain Soils, Xin Qiao

All Dissertations

Irrigation scheduling based on soil moisture sensor readings has gained popularity in the past few decades since it can enhance crop yield while saving water. Such method is limited since the representativeness of an individual soil moisture sensor measurement is questionable in a large field with variable soil type and texture. The optimum location of soil moisture sensors needs to be determined within such a production field for effective sensor-based irrigation scheduling. Therefore, the first object of this study was to investigate the optimum sensor location and the number of moisture sensors required for irrigating cotton in coastal plain soils. …


Design And Synthesis Of Polymer, Carbon And Composite Electrodes For High Energy And High Power Supercapacitors, Margarita Arcila-Velez Dec 2015

Design And Synthesis Of Polymer, Carbon And Composite Electrodes For High Energy And High Power Supercapacitors, Margarita Arcila-Velez

All Dissertations

Supercapacitors (SCs) are promising energy storage devices because they deliver energy faster than Li-ion batteries and store larger amounts of charge compared to dielectric capacitors. SCs are classified in electrical double layer capacitors (EDLCs) and pseudocapacitors, based on their charge storage mechanism. EDLCs store charge electrostatically, i.e. by physical charge separation. This mechanism limits the storable amount of energy to the available surface area of the electrode, typically made of carbon materials, but grants good cycling stability of the SC device. Pseudocapacitor electrodes, commonly made of conducting polymers or metal oxides, store charge faradaically, i.e. through redox reactions throughout the …


Synthesis And Characterization Of Oleophobic Fluorinated Polyester Films, Tugba Demir Dec 2015

Synthesis And Characterization Of Oleophobic Fluorinated Polyester Films, Tugba Demir

All Dissertations

The study presented in this dissertation is dedicated to the synthesis and characterization of oleophobic fluorinated polyester films. Specifically, the blending of oleophilic polyethylene terephthalate (PET) with low surface energy materials such as fluorinated polyesters has been used in order to fabricate oleophobic PET films. First, fluorinated polyesters (P(PF-oate-R)) possessing different end-groups (-COOH, -OH and -CF3) are synthesized via polycondensation reaction of isophthaloyl chloride with perfluoro ether alcohols. Then, they are solvent-blended with PET at various concentrations to obtain oleophobic polyester films of different compositions. In addition, the films are annealed to investigate the effect of annealing on surface properties …


Characterizing The Effective Bandwidth Of Nonlinear Vibratory Energy Harvesters Possessing Multiple Stable Equilibria, Meghashyam Panyam Mohan Ram Dec 2015

Characterizing The Effective Bandwidth Of Nonlinear Vibratory Energy Harvesters Possessing Multiple Stable Equilibria, Meghashyam Panyam Mohan Ram

All Dissertations

In the last few years, advances in micro-fabrication technologies have lead to the development of low-power electronic devices spanning critical fields related to sensing, data transmission, and medical implants. Unfortunately, effective utilization of these devices is currently hindered by their reliance on batteries. In many of these applications, batteries may not be a viable choice as they have a fixed storage capacity and need to be constantly replaced or recharged. In light of such challenges, several novel concepts for micro-power generation have been recently introduced to harness, otherwise, wasted ambient energy from the environment and maintain these low-power devices. Vibratory …


A Time-Efficient Strategy For Relay Selection And Link Scheduling In Wireless Communication Networks, Chenxi Qiu Dec 2015

A Time-Efficient Strategy For Relay Selection And Link Scheduling In Wireless Communication Networks, Chenxi Qiu

All Dissertations

Despite the unprecedented success and proliferation of wireless communication, sustainable reliability and stability among wireless users are still considered important issues in the underlying link protocols. Existing link-layer protocols, like ARQ [44] or HARQ [57,67] approaches are designed to achieve this goal by discarding a corrupted packet at the receiver and performing one or more retransmissions until the packet is successfully decoded or a maximum number of retransmission attempts is reached. These strategies suffer from degradation of throughput and overall system instability since packets need to be en/decode in every hop, leading to high burden for relay nodes especially when …


A Special Protection Scheme Utilizing Trajectory Sensitivity Analysis In Power Transmission, Dan Suriyamongkol Dec 2015

A Special Protection Scheme Utilizing Trajectory Sensitivity Analysis In Power Transmission, Dan Suriyamongkol

All Dissertations

In recent years, new measurement techniques have provided opportunities to improve the North American Power System observability, control and protection. This dissertation discusses the formulation and design of a special protection scheme based on a novel utilization of trajectory sensitivity techniques with inputs consisting of system state variables and parameters. Trajectory sensitivity analysis (TSA) has been used in previous publications as a method for power system security and stability assessment, and the mathematical formulation of TSA lends itself well to some of the time domain power system simulation techniques. Existing special protection schemes often have limited sets of goals and …


Electrochemical Enhancement Of Butanol Production And Xylose Consumption In Pure And Mixed Culture Fermentations, Jovan Popovic Dec 2015

Electrochemical Enhancement Of Butanol Production And Xylose Consumption In Pure And Mixed Culture Fermentations, Jovan Popovic

All Dissertations

The volatility of foreign and domestic petroleum markets has prompted initiatives for the development of alternative liquid energy carriers which have the capacity to accommodate our current transportation infrastructure. Butanol, which has an energy density similar to that of gasoline and can be produced through the fermentation of carbohydrates by solventogenic Clostridia, has been investigated as a supplement or direct replacement to gasoline. However, most butanol fermentations rely on glucose as a feedstock which is in direct competition with our food supply, and this requires the exploration of alternative fermentable substrates. This study investigates the use of electrochemical fermentation modifications …


On Subgrid-Scale Physics In The Convective Atmospheric Surface Layer, Khuong Nguyen Dec 2015

On Subgrid-Scale Physics In The Convective Atmospheric Surface Layer, Khuong Nguyen

All Dissertations

The dynamics of the subgrid-scale (SGS) stress and scalar flux in the convective atmospheric surface layer are studied using field measurements from the Advection Horizontal Array Turbulence Study (AHATS). We extend the array technique previously used to evaluate the SGS velocity and temperature to include measurements of the fluctuating pressure, enabling separation of the resolvable- and subgrid-scale pressure and allowing for the first-ever observations of the pressure covariance terms and the full SGS budgets. Non-dimensional forms of the budget terms are analysed as functions of the surface-layer stability parameter and the ratio of the wavelength of the spectral peak of …


Effects Of Growth Factor Supplementation And Environmental Conditions On Human Adipose-Derived Stem Cell Differentiation Towards Urothelial Lineage, James Turner Dec 2015

Effects Of Growth Factor Supplementation And Environmental Conditions On Human Adipose-Derived Stem Cell Differentiation Towards Urothelial Lineage, James Turner

All Dissertations

In recent years, tissue engineering of the bladder has undergone many technological advances. Autologous urothelial cells have been used in animal models and have shown increased performance for ureteral reconstruction compared to unseeded grafts. However, since patients may lack a reliable source of native urothelial cells due to the nature of their specific bladder disease, autologous cells are not an ideal source clinically, and an alternate cell source must be explored. Adipose derived stem cells (ADSCs) are an attractive cell source for such regenerative medicine applications as they have been extensively studied for their multipotential differentiation, immunosuppressive properties, ease of …


Separation Of Oil From A Brackish Water Stream, Kayli A. Quinton Dec 2015

Separation Of Oil From A Brackish Water Stream, Kayli A. Quinton

Chemical Engineering Undergraduate Honors Theses

In the past 40 years, a variety of enhanced oil recovery (EOR) methods have been developed and applied to mature and mostly depleted oil reservoirs. Chemical and sonic stimulation are two enhanced oil recovery methods in which emulsions are created either as a primary or secondary effect. The resulting emulsion viscosity is considerably lower than that of dry crude thus increasing permeability of and recovery from pay zones. During Chemical enhanced oil recovery, caustic or preformed surfactants are injected into oil reservoirs, which results in flooding and periodic breakthrough of stable oil-water emulsions. The emulsions from chemical enhanced oil recovery …