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Articles 1 - 23 of 23
Full-Text Articles in Engineering
Numerical Investigation Of Vortex Generators And Jet In Cross-Flow Enhancements, Aditya Raman
Numerical Investigation Of Vortex Generators And Jet In Cross-Flow Enhancements, Aditya Raman
Mechanical and Aerospace Engineering Dissertations
Vortex generators have extensively been used over the past few decades for heat transfer applications. Their passive form of enhancement coupled with the ease of their implementation is the primary reason for their growing popularity. The streamwise counter rotating vortex pair (CVP) that is formed downstream of these vortex generators act as a source of energy that can set up stirring scales to enhance heat transfer and improve mixing. The CVP can be used to energize the boundary layer in the case of wall bounded flows, and as a consequence vortex generators have also been used to delay flow separation. …
Towards Artificial Proprioception In The Mandibular Full Arch Fixed Implant Prosthesis, Md Abu Hasan
Towards Artificial Proprioception In The Mandibular Full Arch Fixed Implant Prosthesis, Md Abu Hasan
Mechanical and Aerospace Engineering Dissertations
Full arch fixed implant prosthesis has been one of the most effective treatment modalities for fully edentulous patients over the last few decades. However, due to lack of proprioception occlusal overload is experienced by the prosthesis and its components causing major biomechanical complications such as screw/abutment fracture, framework fracture, and bone loss. The currently available approaches for the overload management rely on external appliances such as an occlusal splint or bite guard and result in occlusal discomfort and high patient dissatisfaction. In this research, an approach to induce artificial proprioception in the full arch fixed implant prosthesis is proposed. However, …
A Framework For Employing Femtosatellites In Planetary Science Missions, Including A Proposed Mission Concept For Titan, Tracie Renea Conn Perez
A Framework For Employing Femtosatellites In Planetary Science Missions, Including A Proposed Mission Concept For Titan, Tracie Renea Conn Perez
Mechanical and Aerospace Engineering Dissertations
Over the past 15 years, there has been a growing interest in femtosatellites, a class of tiny satellites having mass less than 100 grams. Research groups from Peru, Spain, England, Canada, and the United States have proposed femtosat designs and novel mission concepts for them. In fact, Peru made history in 2013 by releasing the first – and still only – femtosat tracked from LEO. However, femtosatellite applications in interplanetary missions have yet to be explored in detail. An interesting operations concept would be for a space probe to release numerous femtosatellites into orbit around a planetary object of interest, …
A Stochastic Distributed Control Allocation Method Using Probability Collectives, Christopher Michael Elliot
A Stochastic Distributed Control Allocation Method Using Probability Collectives, Christopher Michael Elliot
Mechanical and Aerospace Engineering Dissertations
The configuration of the aerospace vehicle of tomorrow marches forward in complexity in step with technological advances in computation, materials, propulsion, and beyond. One of many attributes resulting from this evolution is the multiple effector concept, replacing the traditional aircraft design approach of a dedicated four channel mixer where pitch-roll-yaw-speed is controlled by elevator-aileron-rudder-engine, respectively. Instead, for example on the propulsion front, a distributed suite of smaller engines can substitute the larger power plant and can be used in concert for multiple axis control with both simultaneous, collective thrust for force generation and differential cyclic thrust for moment generation. The …
Numerical Modeling Of Capillary Driven Microfluidic Flow, Md Ashraful Islam
Numerical Modeling Of Capillary Driven Microfluidic Flow, Md Ashraful Islam
Mechanical and Aerospace Engineering Dissertations
Capillary driven two dimensional axisymmetric and three dimensional asymmetric flow in various microfluidic applications have been modeled and analyzed numerically. The transient Navier-Stokes equations are solved using a finite-difference formulation with a two-step projection method on a fixed grid. The vapor-liquid interface of the micro-droplet is tracked by volume-of-fluid (VOF) and coupled level set and volume-of-fluid (CLSVOF) methods with the surface tension force determined by the continuum surface force (CSF) model. The static contact angle at the three phase contact line has been modeled using wall adhesion scheme within the CSF framework. The developed numerical method for capturing the microfluidic …
System Health Monitoring Using Multiple-Model Adaptive Estimation Techniques, Stanley Ryan Sifford
System Health Monitoring Using Multiple-Model Adaptive Estimation Techniques, Stanley Ryan Sifford
Mechanical and Aerospace Engineering Dissertations
Monitoring system health for fault detection and diagnosis by tracking system parameters concurrently with state estimates is approached using a new multiple-model adaptive estimation (MMAE) method. This novel method is called GRid-based Adaptive Parameter Estimation (GRAPE). GRAPE expands existing MMAE methods by using new techniques to sample the parameter space. GRAPE expands on MMAE with the hypothesis that sample models can be applied and resampled without relying on a predefined set of models. GRAPE is initially implemented in a linear framework using Kalman filter models. A more generalized GRAPE formulation is presented using extended Kalman filter (EKF) models to represent …
Pilot Demonstration Based Reinforcement Learning With Application To Low Speed Airship Control, Onur Daskiran
Pilot Demonstration Based Reinforcement Learning With Application To Low Speed Airship Control, Onur Daskiran
Mechanical and Aerospace Engineering Dissertations
Designing control systems for airship has unique challenges as compared to conventional aircraft. Highly nonlinear dynamics, different mass/inertia relations, vast uncertainties in the model parameters and underactuation are the main reasons behind this. Airship dynamics is greatly influenced by the variations in the environmental (e.g.,room temperature) and internal (e.g., helium distribution in envelope) factors that can completely change the response characteristics of the blimp and make it infeasible for a model-based controller to perform. On the other hand, a skilled RC pilot can operate the manual flight easily under these conditions. This makes LfD (learning from demonstration) and RL (reinforcement …
On The Enhancement Of Thermo-Mechanical And Impact Reliability Of Passive And Active Microelectronic Devices, A R Nazmus Sakib
On The Enhancement Of Thermo-Mechanical And Impact Reliability Of Passive And Active Microelectronic Devices, A R Nazmus Sakib
Mechanical and Aerospace Engineering Dissertations
Microelectronic devices are an essential part of human life. The idea of Internet of Things (IoT) where all the everyday devices will be connected with each other transmitting information and operating on their own is becoming very popular. A silicon chip which has millions of transistors in it, has been the heart and brain of the everyday components ranging from personal entertainment, communication to Automotive ECU (electronic control Unit), and health care management systems to home security systems. Every aspect of modern human experience is dependent on this tiny silicon chip. Microelectronic devices can be divided into two broad categories …
Investigation Of Exothermic Reaction Dynamics Via Computational Fluid Dynamics Coupled With A Feedback Controller, Siusan Choi
Investigation Of Exothermic Reaction Dynamics Via Computational Fluid Dynamics Coupled With A Feedback Controller, Siusan Choi
Mechanical and Aerospace Engineering Dissertations
The control of reaction temperature under continuous flow conditions is important in a variety of chemical manufacturing industries. For many reactions, operating at off-design temperatures can result in the production of undesired products, reduced feedstock conversion and, in some cases, reduced catalyst lifetime. In many exothermic reactions, maintaining a desired set point temperature at high reactant flow rates becomes challenging if the chemical kinetics exhibit highly non-linear behavior. In these situations, the interaction between commonly used linear controllers and the physical system can lead to unexpected dynamic response and undesired swings in reaction temperature. In this research, a computational model …
General Solutions To Temperature Distribution In Orthotropic Systems Subject To Variable Heat Transfer And Biological Systems During Bioheat Transfer, Daipayan Sakar
Mechanical and Aerospace Engineering Dissertations
Bioheat transfer is the phenomenon of heat transfer in biological systems where the dominant modes of heat transfer are conduction and advection. Other factors such as rate of metabolism that are unique to biological systems contribute significantly towards bioheat transfer. In the present work, the Pennes bioheat equation has been solved for a multilayer system to derive steady state and transient temperature solutions in the multilayer skin tissue with a tumor. In nanoparticle based hyperthermia therapy, the body temperature elevates from the physiological core body temperature, 37 deg. C. Analytical solutions for three different therapeutic techniques have been developed to …
Integration Of A Portfolio-Based Approach To Evaluate Aerospace R&D Problem Formulation Into A Parametric Synthesis Tool, Amit R. Oza
Mechanical and Aerospace Engineering Dissertations
The focus of this study is to improve R&D effectiveness towards aerospace and defense planning in the early stages of the product development lifecycle. Emphasis is on: correct formulation of a decision problem, with special attention to account for data relationships between the individual design problem and the system capability required to size the aircraft, understanding of the meaning of the acquisition strategy objective and subjective data requirements that are required to arrive at a balanced analysis and/or “correct” mix of technology projects, understanding the meaning of the outputs that can be created from the technology analysis, and methods the …
Performance Analysis, Dynamic Simulation And Control Of Mass-Actuated Airplane, Sukru Akif Erturk
Performance Analysis, Dynamic Simulation And Control Of Mass-Actuated Airplane, Sukru Akif Erturk
Mechanical and Aerospace Engineering Dissertations
The control of space, aerial and underwater vehicles requires moment generation mechanisms to change their orientation. In addition to or in place of conventional moment generation actuators, internally moving-mass actuation has been proposed and/or used for such vehicles. The primary principle for mass-actuation is to reposition gravitational force to change the associated moment while the secondary effect may come from the inertial force due to the motion of the masses. Recent development/miniaturization in flight control sensor, computing and actuation, and electric motors and expansion of applications for small UAV (Unmanned Aerial Vehicle) offer a potential for implementation of internal mass-actuation …
Complex Multidisciplinary System Composition For Aerospace Vehicle Conceptual Design, Alexis R. Gonzalez
Complex Multidisciplinary System Composition For Aerospace Vehicle Conceptual Design, Alexis R. Gonzalez
Mechanical and Aerospace Engineering Dissertations
Although, there exists a vast amount of work concerning the analysis, design, integration of aerospace vehicle systems, there is no standard for how this data and knowledge should be combined in order to create a synthesis system. Each institution creating a synthesis system has in house vehicle and hardware components they are attempting to model and proprietary methods with which to model them. This leads to the fact that synthesis systems begin as one-off creations meant to answer a specific problem. As the scope of the synthesis system grows to encompass more and more problems, so does its size and …
Experimental Investigation Of Methane Reformer With A Continuous Flow Reactor, Xiao Zhang
Experimental Investigation Of Methane Reformer With A Continuous Flow Reactor, Xiao Zhang
Mechanical and Aerospace Engineering Dissertations
Over the decades, seeking for an alternative energy source has been more and more significant because of increasing demand with rapid industry expansion. Liquid hydrocarbon from Fischer-Tropsch process is considered as an alternative fuel source because the product is considered as subtle for petroleum-derived. Syngas as feedstock for F-T process plays a crucial role in liquid hydrocarbon production. Among several commercial and experiment technologies, the most common technology for syngas production is natural gas reforming. The product from reforming process has proper carbon monoxide/hydrogen ratio for direct application in F-T synthesis. Meanwhile, combined carbon dioxide into reforming reaction has attracted …
The Effects Of Temperature And Relative Humidity On Exposure Of Legacy And Future Technology Hardware, Under Real Data Center Conditions In An Ansi/Isa Classified G2 Environment, Oluwaseun Michael Awe
The Effects Of Temperature And Relative Humidity On Exposure Of Legacy And Future Technology Hardware, Under Real Data Center Conditions In An Ansi/Isa Classified G2 Environment, Oluwaseun Michael Awe
Mechanical and Aerospace Engineering Dissertations
It is well established that it is safe to operate information technology (IT) equipment in a G1 classified contaminant severity level when operating within specified ASHRAE recommended and allowable limits in an air-side economizer data center. This is basis for which electronic equipment manufacturers provide warranty for their products. IT equipment manufacturers in the US now requires data centers operators to demonstrate that they meet all the specified conditions consistently before fulfilling warranty equipment failure. This places limitation to where data center utilizing air-side economizer can be located. In order to determine the reliability of electronic hardware in higher severity …
Analysis Of Composite Beams With Airfoil Cross-Sections With I-Section Stiffener Under Tension And Bi-Directional Moments, Peter Louis Leboulluec
Analysis Of Composite Beams With Airfoil Cross-Sections With I-Section Stiffener Under Tension And Bi-Directional Moments, Peter Louis Leboulluec
Mechanical and Aerospace Engineering Dissertations
Annual wind power generation capacity in the US has increased from 3 gigawatts in 2000 to 61 gigawatts in 2013 and is on track to fulfill 20% of projected U.S. electricity needs (305 gigawatts) by 2030. To enable the increase in electricity generation of wind turbines, longer blades are being designed which require improved engineered blades to handle higher loads. Thus, the wind turbine industry is turning to the use of carbon-epoxy composite materials to take advantage of their low weight yet high strength ratio and improved fatigue resistance. Current analyses to design turbine blades utilize either Finite Element Analysis …
Thermal Energy Storage For Expanded Use Of Data Center Indirect/Direct Evaporative Cooling, Jefferey Luttrell
Thermal Energy Storage For Expanded Use Of Data Center Indirect/Direct Evaporative Cooling, Jefferey Luttrell
Mechanical and Aerospace Engineering Dissertations
Computer cooling system design evolved over time with goals of increasing efficiency and decreasing cost. Early computers were essentially hand-built and very expensive. Reliable operation required aggressive cooling to maintain acceptable component temperatures and this was achieved with relatively low ventilation air temperatures. With time, the scale of operations increased to the point that operating cost began to strongly influence design decisions. Computer room air conditioners consumed substantial amounts of electrical power, in some situations almost as much power as the computer equipment. One cost saving idea used outside air when the ambient temperature fell below the normal cooling supply …
Complex Multidisciplinary Systems Decomposition For Aerospace Vehicle Conceptual Design And Technology Acquisition, Amen Omoragbon
Complex Multidisciplinary Systems Decomposition For Aerospace Vehicle Conceptual Design And Technology Acquisition, Amen Omoragbon
Mechanical and Aerospace Engineering Dissertations
Although, the Aerospace and Defense (A&D) industry is a significant contributor to the United States’ economy, national prestige and national security, it experiences significant cost and schedule overruns. This problem is related to the differences between technology acquisition assessments and aerospace vehicle conceptual design. Acquisition assessments evaluate broad sets of alternatives with mostly qualitative techniques, while conceptual design tools evaluate narrow set of alternatives with multidisciplinary tools. In order for these two fields to communicate effectively, a common platform for both concerns is desired. This research is an original contribution to a three-part solution to this problem. It discusses the …
Numerical Modeling Of An Alloy Droplet Deposition With Non-Equilibrium Solidification, Vimal Ramanuj
Numerical Modeling Of An Alloy Droplet Deposition With Non-Equilibrium Solidification, Vimal Ramanuj
Mechanical and Aerospace Engineering Dissertations
Droplet deposition is a process of extensive relevance to the microfabrication industry. Various bonding and film deposition methods utilize single or multiple droplet impingements on a substrate with subsequent splat formation through simultaneous spreading and solidification. Splat morphology and solidification characteristics play vital roles in determining the final outcome. Experimental methods have limited reach in studying such phenomena owing to the extremely small time and length scales involved. Fundamental understanding of the governing principles of fluid flow, heat transfer and phase change provide effective means of studying such processes through computational techniques. The present study aims at numerically modeling and …
Data Engineering In Aerospace Systems Design & Forecasting, Eric Haney
Data Engineering In Aerospace Systems Design & Forecasting, Eric Haney
Mechanical and Aerospace Engineering Dissertations
Although engineers spend the majority of their time finding, managing, and transforming data, the process of how to handle data remains under-educated & under-researched. The alignment of engineering education & proficiency along an analysis-dominated mindset is ill-conditioned for the growing reliance on data-driven processes and holistic decision-making requirements. Although a majority of driving decisions in the aerospace industry rely heavily on utilizing existing organizational data-stores and built-in knowledge bases to make informed decisions, formalized development & implementation of data within existing engineering processes is seldom addressed. The current research defines a complementary discipline, Data-Engineering, which seeks to capitalize on the …
Exergy Analysis Of A Pulse Detonation Engine Linear Power Generator, Raheem Temitope Bello
Exergy Analysis Of A Pulse Detonation Engine Linear Power Generator, Raheem Temitope Bello
Mechanical and Aerospace Engineering Dissertations
The fuel efficiency of a power generator is a key metric for evaluating its performance. The common engineering practice is to determine the thermal efficiency of the system by applying the conservation of energy also known as the first law of thermodynamics. However, for heat engine power generators, and other thermal systems, the thermal efficiency is not sufficient for detailed system performance analysis. Exergy analysis, which applies both the first and second law of thermodynamics, enables the determination of the directionality of thermal processes, and the system’s available work. This more complete thermodynamic analysis approach is applied to a pulse …
Enhanced Specific Heat Of Molten Salt Nanofluids, Hani Tiznobaik
Enhanced Specific Heat Of Molten Salt Nanofluids, Hani Tiznobaik
Mechanical and Aerospace Engineering Dissertations
Concentrated solar power uses general thermodynamic cycles (such as Rankine or Gas turbine cycle) to produce electricity and thus its efficiency primarily relies on the operating temperature of thermal energy storage. Current thermal energy storage medium is organic material such as synthetic oil or fatty acid. However, these materials are not stable at high temperatures due to their thermal decomposition. Using molten salts as thermal energy storage medium is a very attractive option since they are thermally stable at high temperatures (over 600 °C). They also have very lower vapor pressure (for reducing mechanical stress on structure materials), less reactive, …
Maximizing Use Of Air-Side Economization, Direct And Indirect Evaporative Cooling For Energy Efficient Data Centers, Betsegaw Kebede Gebrehiwot
Maximizing Use Of Air-Side Economization, Direct And Indirect Evaporative Cooling For Energy Efficient Data Centers, Betsegaw Kebede Gebrehiwot
Mechanical and Aerospace Engineering Dissertations
Data centers house information technology (IT) equipment such as servers and network switches which are vital for our networked modern society by providing digital data storage, data processing and connectivity. Data centers house few hundreds to tens of thousands of IT equipment that consume few kilowatt-hours to multi-megawatt-hours of electrical energy that gets dissipated as heat. IT equipment need to be properly cooled so that they operate reliably for their expected lifetime. For air cooled IT equipment, manufacturers provide heat sinks, cold plates, fans, et cetera to remove heat from the vicinity of heat dissipating components and data centers need …