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Articles 31 - 60 of 904
Full-Text Articles in Engineering
Policy Design Tool For Managing Indoor Residential Water Demand In Water-Scarce Regions, Mujahed M. Thneibat
Policy Design Tool For Managing Indoor Residential Water Demand In Water-Scarce Regions, Mujahed M. Thneibat
Open Access Dissertations
In view of population growth; climate change; and economic evolution, water resources in numerous parts of the world have reached their natural capacities. Consequently, the ability of many countries to grow; meet the basic needs of inhabitants; and protect the environment will be endangered like never before unless water resources are smartly handled and managed. ^ In the past few decades, many developed and developing countries have suffered from water scarcity, and more are certain to follow. The water security dilemma is much more challenging in developing countries. Water utilities have had to follow regulatory plans to manage demand on …
Fracture Analysis In Biomimetic Bouligand Architectures, Nobphadon Suksanqpanya
Fracture Analysis In Biomimetic Bouligand Architectures, Nobphadon Suksanqpanya
Open Access Dissertations
The Bouligand structure, which is found in many biological materials, is a hierarchical architecture that features uniaxial fiber layers assembled periodically into a helicoidal pattern. Many studies have highlighted the high damage-resistant performance of Bouligand structures and its biomimetic materials. One of the outstanding species with the Bouligand structures is the smashing Mantis Shrimp, Odontodactylus Scyllarus, (or stomatopod) due to its capability of generating high speed, high acceleration blows using its raptorial appendage to defeat highly armored preys. The load-bearing part of this appendage, the dactyl club, contains an interior region, which is mainly characterized by the Bouligand structure. This …
Fundamental Studies Of Flame Propagation In Lean-Burn Natural Gas Engines, Zhiyan Wang
Fundamental Studies Of Flame Propagation In Lean-Burn Natural Gas Engines, Zhiyan Wang
Open Access Dissertations
Lean-burn natural gas engines offer enhanced thermal efficiencies and reduced soot and NOx emissions. However, cycle-to-cycle variability in combustion that can result from unreliable ignition, variability in equivalence ratio and quenching is a challenge. Reliability of ignition can be improved by employing a dual-fuel ignition strategy in which a small quantity of diesel fuel is injected to initiate ignition. Computational studies of n-heptane/methane-air mixing layers are performed to provide insight into the fundamental physics of dual-fuel ignition. The results show that the characteristic time required for steady premixed flame propagation has three components: time for autoignition to occur, time for …
Approximate Computing: An Integrated Cross-Layer Framework, Swagath Venkataramani
Approximate Computing: An Integrated Cross-Layer Framework, Swagath Venkataramani
Open Access Dissertations
A new design approach, called approximate computing (AxC), leverages the flexibility provided by intrinsic application resilience to realize hardware or software implementations that are more efficient in energy or performance. Approximate computing techniques forsake exact (numerical or Boolean) equivalence in the execution of some of the application’s computations, while ensuring that the output quality is acceptable. While early efforts in approximate computing have demonstrated great potential, they consist of ad hoc techniques applied to a very narrow set of applications, leaving in question the applicability of approximate computing in a broader context.
The primary objective of this thesis is to …
Computer Vision-Based Structural Assessment Exploiting Large Volumes Of Images, Chul Min Yeum
Computer Vision-Based Structural Assessment Exploiting Large Volumes Of Images, Chul Min Yeum
Open Access Dissertations
Visual assessment is a process to understand the state of a structure based on evaluations originating from visual information. Recent advances in computer vision to explore new sensors, sensing platforms and high-performance computing have shed light on the potential for vision-based visual assessment in civil engineering structures. The use of low-cost, high-resolution visual sensors in conjunction with mobile and aerial platforms can overcome spatial and temporal limitations typically associated with other forms of sensing in civil structures. Also, GPU-accelerated and parallel computing offer unprecedented speed and performance, accelerating processing the collected visual data. However, despite the enormous endeavor in past …
Tangible Interaction As An Aid For Object Navigation In 3d Modeling, Sanmathi Dangeti
Tangible Interaction As An Aid For Object Navigation In 3d Modeling, Sanmathi Dangeti
Open Access Theses
This study introduced an interaction technique that used tangible interaction for 3D modeling. A hybrid interaction technique using a Kinect camera and a smartphone with a gyroscope was developed for the navigating objects in a 3D modeling software. It was then tested on 20 participants categorized as amateurs who had basic 3D/ CAD modeling experience and 20 participants categorized as the experts who had extensive experience working with the modeling software. This research study presents the need for existence of such interaction technique, gaps from the related previous studies, statistical findings from the current study and possible reasons for the …
Assessing Fuel Burn Inefficiencies In Oceanic Airspace, Stephen Builta
Assessing Fuel Burn Inefficiencies In Oceanic Airspace, Stephen Builta
Open Access Theses
Increasing the efficiency of aircraft operations offers a shorter term solution to decreasing aircraft fuel burn than fleet replacement. By estimating the current airspace inefficiency, we can get an idea of the upper limit of savings. Oceanic airspace presents a unique opportunity for savings due to increased separation differences vs. overland flight.
We assess fuel burn inefficiency by comparing estimated fuel burn for real world flights with the estimated optimal fuel burn. For computing fuel burn, we use the Base of Aircraft Data (BADA) with corrections based on research by Yoder (2005). Our fuel burn results show general agreement with …
Multimedia Techniques For Construction Education And Training, Wayne A. Bunnell
Multimedia Techniques For Construction Education And Training, Wayne A. Bunnell
Open Access Theses
The current profession of civil engineering often focuses education and training on code compliance rather than constructability and construction techniques. Also, it is well accepted that it takes a decade or more for engineers to develop a high-level project construction understanding and many state departments of transportation rely on in-field training for entry-level inspectors, with little or no education provisions for contractors. This research investigated the use of time-lapse photography to develop training and education material that will improve the understanding of project construction and crucial quality control specifications of an entry-level engineer, contractor, or inspector. Overall, the project team …
Sugarcane Bagasse Hydrolysis Enhancement Using Bsa, Antonio Carlos Freitas Dos Santos
Sugarcane Bagasse Hydrolysis Enhancement Using Bsa, Antonio Carlos Freitas Dos Santos
Open Access Theses
Lignocellulose is composed of polysaccharides linked to lignin and other aromatic compounds, making the sugars not readily available to fermentation. This entails that biomass must go through the unit operations of pretreatment and enzyme hydrolysis. Pretreatment opens the structure to allow the enzymes to act on and hydrolyze cellulose and hemicellulose to glucose and/or xylose which in turn are fermented to ethanol. Concomitantly, the enzymes interact with soluble phenols and insoluble solids derived from lignin that inhibit hydrolysis. This leads to high enzyme loadings and higher production costs. Soluble phenols can be eliminated through washing. Insoluble lignin, however, demands another …
Size Scaling Of Strength And Toughness For 3d Printed Polymer Specimens, Darren Thomas Bell
Size Scaling Of Strength And Toughness For 3d Printed Polymer Specimens, Darren Thomas Bell
Open Access Theses
To find material systems that offer low density and high strength, stiffness or toughness, hierarchically designed material systems have provided a promising research area. This thesis lays the groundwork for designing efficient micro-architectured material systems by characterizing size effects for 3d printed polymer parts. Two methods were used to analyze data from 3-point bend tests for specimens of varying size: the load-separation method was used for finding the point of crack growth initiation and Bazant’s method was used to find shape independent strength at failure. The strength values were used as inputs for finding size independent material constants within a …
Thermal Transport In Lithium Ion Batteries: An Experimental Investigation Of Interfaces And Granular Materials, Aalok Jaisheela Uday Gaitonde
Thermal Transport In Lithium Ion Batteries: An Experimental Investigation Of Interfaces And Granular Materials, Aalok Jaisheela Uday Gaitonde
Open Access Theses
Increasing usage and recent accidents due to lithium-ion (Li-ion) batteries exploding or catching on fire has inspired research on the characterization and thermal management of these batteries. In cylindrical 18650 cells, heat generated during the battery's charge/discharge cycle is poorly dissipated to the surrounding through its metallic case due to the poor thermal conductivity of the jelly roll, which is spirally wound with many interfaces between electrodes and the polymeric separator. This work presents a technique to measure the thermal conduction across the metallic case-plastic separator interface, which ultimately limits heat transfer out of the jelly roll.
The polymeric separator …
Secondary Instabilities Of Hypersonic Stationary Crossflow Waves, Joshua Benjamin Edelman
Secondary Instabilities Of Hypersonic Stationary Crossflow Waves, Joshua Benjamin Edelman
Open Access Theses
A sharp, circular 7° half-angle cone was tested in the Boeing/AFOSR Mach-6 Quiet Tunnel at 6° angle of attack. Using a variety of roughness configurations, measurements were made using temperature-sensitive paint (TSP) and fast pressure sensors. High-frequency secondary instabilities of the stationary crossflow waves were detected near the aft end of the cone, from 110° to 163° from the windward ray.
At least two frequency bands of the secondary instabilities were measured. The secondary instabilities have high coherence between upstream and downstream sensor pairs. In addition, the amplitudes of the instabilities increase with the addition of roughness elements near the …
Implementing A Wireless Monitoring Solution For A Biomechanical Telemetry System, Hyung Suk Kim
Implementing A Wireless Monitoring Solution For A Biomechanical Telemetry System, Hyung Suk Kim
Open Access Theses
Sport-related Traumatic Brain Injury (TBI) is one of the major concerns for collision based sports athletes and their families. The ability to measure impacts on the head is imperative to monitor brain injury and prevent serious TBI. Recent research by the Purdue Neurotrauma Group (PNG) indicates that accumulation of subconcussive impacts may cause permanent neurological damage. Currently available commercial impact monitoring systems are designed as an event-based models which collect impact data above pre-determined acceleration thresholds. To track long-term effects of sub-concussive impacts, event-based modeling is inadequate. The PNG developed a biomechanical sports telemetry system that is capable of storing …
Design And Plan Of A Modified Hydroponic Shipping Container For Research, John A. Houtman
Design And Plan Of A Modified Hydroponic Shipping Container For Research, John A. Houtman
Open Access Theses
As the world’s population continues to increase, food production will need to increase in order to meet the predicted rise in food demand. However, with increased pressure on cropland available from environmental effects and urbanization, new innovative methods of crop production need to be researched in order to increase agricultural production with limited land. This research focuses on the design of a single form of urban agriculture that is considered Zfarming and has the potential to produce quality urban agricultural produce through ground-based measures. This project produced detailed step-by-step analysis of the design process, develop variability within the modified hydroponic …
Improvement Of A Biomechanical Telemetry System Hardware Platform, Soon Ho Kwon
Improvement Of A Biomechanical Telemetry System Hardware Platform, Soon Ho Kwon
Open Access Theses
Traumatic brain injuries (TBI) while playing sports are a major concern for the general public today. Recently, studies have shown that repetitive subconcussive hits can lead to neurological disorders. In order to prevent the athletes from suffering traumatic brain injuries, many organizations related to contact based sports and the military employ commercialized head impact telemetry systems. However, a majority of the commercialized systems is event based which only collects the linear acceleration that exceeds a certain threshold. To accurately record and utilize the data from the impact telemetry system, it is necessary to record all the linear and angular acceleration …
Design Of Nitroxide-Based Radical Polymer Materials For Electronic Applications, Martha E. Hay
Design Of Nitroxide-Based Radical Polymer Materials For Electronic Applications, Martha E. Hay
Open Access Theses
Radical polymers represent a new class of organic electronic materials that rely on an oxidation-reduction (redox) reaction to transport charge. That is, stable radical sites pendant to the polymer backbone communicate electronically through a rapid oxidation-reduction reaction. This redox mechanism has previously been established as effective for charge-storage applications (e.g., secondary batteries). When applied in the solid state, radical polymers demonstrate electrical conductivity on par with that of first-generation conjugated polymer electronic materials. This initial success has prompted interest in developing design rules for radical polymers. Specifically, this thesis explores the impact of radical density in a polymer …
Computational Investigation Of Force Generation, Relaxation, And Remodeling Of The Actin Cytoskeleton, Wonyeong Jung
Computational Investigation Of Force Generation, Relaxation, And Remodeling Of The Actin Cytoskeleton, Wonyeong Jung
Open Access Theses
Diverse mechanics of the F-actin cytoskeleton mediate essential behaviors of cells, including cell division, migration, and shape change. Force generation by motor proteins and the resultant morphological change of cytoskeletal networks govern cellular processes such as migration and division. Cell stiffening and softening under external mechanical stimuli regulate cell shape. In this thesis, interplay between various cytoskeletal components during these processes is investigated using an agent-based computational model to elucidate mechanical factors underlying these processes. This thesis is composed of three independent studies.
First, force generation in cortical actomyosin networks is studied. Using the computational model, the effects of motor …
Degradation Of High Performance Polymeric Fibers: Effects Of Sonication, Humidity And Temperature On Poly (P-Phenylene Terephthalamide) Fibers, Nelyan Lopez-Perez
Degradation Of High Performance Polymeric Fibers: Effects Of Sonication, Humidity And Temperature On Poly (P-Phenylene Terephthalamide) Fibers, Nelyan Lopez-Perez
Open Access Theses
High performance fibers are characterized by properties such as high strength and resistance to chemicals and heat. Due to their outstanding properties, they are used on applications under harsh environments that can degrade and decrease their performance. Fiber degradation due to different chemical and mechanical factors, is a process that begins at a microstructural level. Changes in the polymer’s chemical or physical structure can alter their mechanical properties. Knowledge of the structure-properties relationship and the effects of environmental chemical and physical factors over time, is crucial for the improvement and development of high performance fibers.
In this study ballistic fibers …
Mathematical Analysis Of Feedback Targets Of Bmp Signaling In Drosophila Embryonic Development, Yan Luo
Mathematical Analysis Of Feedback Targets Of Bmp Signaling In Drosophila Embryonic Development, Yan Luo
Open Access Theses
Bone morphogenetic proteins (BMPs) drive a range of cellular processes especially in the early stages of embryonic development. This family of proteins acts as one of the most important extracellular signals in development pattern formation across the animal kingdom. Cells in embryos differentiate into different cell types in response to the concentration level of BMP. This complex process is regulated by multiple regulators that serve to tune the signal response.
Extensive experimental and computational research has been performed to analyze BMP regulation in Drosophila, a widely studied model organism, and has advanced our understanding of animal development. Because of …
New Screening Method For Overweight Vehicles, Goran Veljko Milutinovic
New Screening Method For Overweight Vehicles, Goran Veljko Milutinovic
Open Access Theses
Throughout the U.S., state agencies are issuing an increasingly large number of permits for overweight vehicles every year. There are various methods used by state agencies to process permit requests; the Indiana Department of Transportation employs a screening process that consists of the Tennessee Formula (allowable weight is determined and checked, for every axle group) in combination with the Gross Vehicle Weight limit. If a permit truck satisfies these two screening criteria, it is permitted; otherwise, it is further processed with refined analyses. The Tennessee Formula is based on Allowable Stress Design. However, most design and evaluation conducted today is …
Reaction Tuning Of Selectively Deposited Nano-Thermite Inks For Thrust And Heat Deposition, Raghav Ramachandran
Reaction Tuning Of Selectively Deposited Nano-Thermite Inks For Thrust And Heat Deposition, Raghav Ramachandran
Open Access Theses
Currently there is very little systematic work that quantifies the performance of energetic materials in terms of thrust or heat deposition applied to electronic circuits. A better understanding of the interactions between nano-scale energetic materials and electronic systems, as a function of stoichiometry is needed for enhanced defeat. Both of these needs are addressed in this research. Formulations of Al-CuO and Al-Bi2O3 nano-thermites were prepared at different equivalence ratios and selectively deposited onto silicon substrates and thrust and heat deposition of these materials was quantified. Both nano-thermite systems produced maximum thrust near stoichiometric ratios, and more fuel-rich mixtures led to …
Early Bearing Fault Analysis Using High Frequency Enveloping Techniques, Ilya Shulkin
Early Bearing Fault Analysis Using High Frequency Enveloping Techniques, Ilya Shulkin
Open Access Theses
High frequency acceleration enveloping is one of many tools that vibration analysts have at their disposal for the diagnosis of bearing faults in rotating machinery. This technique is believed to facilitate very early detection of potential failures by detecting low amplitude repetitive impacts in frequency ranges above conventional condition monitoring. One traditional enveloping method uses a mathematical operation known as the Hilbert transform along with other signal processing procedures such as band-pass filtering and full-wave rectification. For comparison, another method uses a proprietary algorithm included in National Instruments’ LabVIEWTM add-on package: Sound and Measurement Suite. Enveloping’s inherent problem with noise …
Integration Of Bim And Utility Sensor Data For Facilities Management, Kamal Suprabhas
Integration Of Bim And Utility Sensor Data For Facilities Management, Kamal Suprabhas
Open Access Theses
Building information modelling represents a building as a database of coordinated, consistent and computable information in construction (Sabol, 2008). There has been a recent trend to study the usage of BIM for post-construction facility management. Recently, attempts are also being made to link a BIM model with smart sensing technology or building automation systems (BAC). This thesis aims to investigate the feasibility of using sensor data from mote based light sensors tied to a BIM model, to be used for maintenance based facility management. More specifically, a prototype will be developed that integrates lighting sensor data collected using a mote …
Investigation Of Thin Film Thermal Transport Using Micro-Raman Thermometry And Tip Enhanced Raman Spectroscopy, Mithun Srinivasan
Investigation Of Thin Film Thermal Transport Using Micro-Raman Thermometry And Tip Enhanced Raman Spectroscopy, Mithun Srinivasan
Open Access Theses
In recent years, a steady increase in the need for packing more energy in smaller devices had driven the need for better understanding of thermal transport in thin films and designing methods to manipulate them. This can be attributed as the reason for numerous efforts made in the past decade to achieve temperature resolution at nanoscale. Such techniques can help us in understanding the thermal conductivity of thin films which can result in an improved performance of these devices. The temperature probing technique must be non-invasive to avoid damaging the vulnerable thin films, fast to study the energy transport and …
Linking Nanoscale Mechanical Behavior To Bulk Physical Properties And Phenomena Of Energetic Materials, Matthew R. Taw
Linking Nanoscale Mechanical Behavior To Bulk Physical Properties And Phenomena Of Energetic Materials, Matthew R. Taw
Open Access Theses
The hardness and reduced modulus of aspirin, RDX, HMX, TATB, FOX-7, ADAAF, and TNT/CL-20 were experimentally measured with nanoindentation. These values are reported for the first time using as-received micron sized crystals of energetic materials with no additional mechanical processing. The results for TATB, ADAAF, and TNT/CL-20 are the first of their kind, while comparisons to previous nanoindentation studies on large, carefully grown single crystals of the other energetic materials show that mechanical properties of the larger crystals are comparable to crystals in the condition they are practically used. Measurements on aspirin demonstrate the variation that can occur between nanoindentation …
Trajectory Optimization Using Indirect Methods And Parametric Scramjet Cycle Analysis, Joseph Williams
Trajectory Optimization Using Indirect Methods And Parametric Scramjet Cycle Analysis, Joseph Williams
Open Access Theses
This study investigates the solution of time sensitive regional strike trajectories for hypersonic missiles. This minimum time trajectory is suspected to be best performed by scramjet powered hypersonic missiles which creates strong coupled interaction between the flight dynamics and the performance of the engine. Comprehensive engine models are necessary to gain better insight into scramjet propulsion. Separately, robust and comprehensive trajectory analysis provides references for vehicles to fly along. However, additional observation and understanding is obtained by integrating the propulsion model inside the trajectory framework. Going beyond curve fitted thrusting models, an integrated scramjet cycle analysis offers rapid trade studies …
Metrics Of Critical Pair Identification, Zixu Zhang
Metrics Of Critical Pair Identification, Zixu Zhang
Open Access Theses
Critical Pair Identification works as a potential assistive tool for human air traffic controllers by identifying potentially dangerous situations that are not detected by proposed automated separation assurance systems. This concept specifically considers conflicts that might arise if aircraft unexpectedly deviate from their planned flight path in the near future. Five metrics of the critical pair concept, Critical Pair Count, Time to Risk Exposure, Lead Time, Risk Exposure Duration and Blunder Sensitivity Index, have been developed and mathematically defined to characterize the safety level of an aircraft pair or a volume of air space. Algorithm that computes proposed metrics is …
The Influence Of Alkalinity Of Portland Cement On The Absorption Characteristics Of Superabsorbent Polymers (Sap) For Use In Internally Cured Concrete, Juan D. Tabares Tamayo
The Influence Of Alkalinity Of Portland Cement On The Absorption Characteristics Of Superabsorbent Polymers (Sap) For Use In Internally Cured Concrete, Juan D. Tabares Tamayo
Open Access Theses
The concrete industry increasingly emphasizes advances in novel materials that promote construction of more resilient infrastructure. Due to its potential to improve concrete durability, internal curing (IC) of concrete by means of superabsorbent polymers (SAP) has been identified as one of the most promising technologies of the 21st century. The addition of superabsorbent polymers into a cementitious system promotes further hydration of cement by providing internal moisture during the hardening and strength development periods, and thus limits self-desiccation, shrinkage, and cracking.
This thesis presents the work performed on the series of cement pastes with varying alkalinity of their pore solutions …
Helical Strakes On High Mast Lighting Towers And Their Effect On Vortex Shedding Lock-In, Ayah Zahour
Helical Strakes On High Mast Lighting Towers And Their Effect On Vortex Shedding Lock-In, Ayah Zahour
Open Access Theses
An experimental study on the effect of helical strakes on vortex induced vibrations and the lock-in phenomenon in High Mast Lighting Towers (HMLTs) is investigated. Two multi-sided tapered scaled models are clamped in place in a subsonic wind tunnel that is equipped with a hot-wire sensor and a traverse mechanism. The shedding frequency data is collected for the models with and without helically patterned strakes with the use of two different ropes. The responses of the tower models, for a Reynolds number of 44, 000, are compared and discussed under different configurations including: two directions of the model with respect …
Free Edge Stress Analysis Of Laminated Structures With Arbitrary Cross Sections Using Mechanics Of Structure Genome, Lingxuan Zhou
Free Edge Stress Analysis Of Laminated Structures With Arbitrary Cross Sections Using Mechanics Of Structure Genome, Lingxuan Zhou
Open Access Theses
Composite laminates have been increasingly used in advanced structural applications, due to their excellent strength-to-weight properties and considerable flexibility on designing with respect to the laminate layup. However, the heterogeneity and anisotropy of composite laminates have brought many challenges for analysis and numerous researches have been devoted in this field. A well known problem which has been studied intensively is the so-called free-edge problem. It states that due to the mismatch in elastic properties of adjacent layers, full-scale three-dimensional (3D) and highly concentrated stress fields will occur in the vicinity of the free edges. The interlaminar stresses grow very rapidly …