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Articles 1 - 30 of 48
Full-Text Articles in Mechanical Engineering
Evaluating The Use Of Functional Representations For Ideation In Conceptual Design, Benjamin Caldwell
Evaluating The Use Of Functional Representations For Ideation In Conceptual Design, Benjamin Caldwell
All Dissertations
Functional representations are often used in the conceptual stages of design because they encourage the designer to focus on the intended use and purpose of a system rather than the physical solution. Function models have been proposed by many researchers as a tool to expand the solution search space and guide concept generation, and many design tools have been created to support function-based design. These tools require designers to create function models of new or existing artifacts, but there is limited published research describing what types of functions should be included in a model or the appropriate level of abstraction …
An Investigation Of The Application Of Phase Change Materials In Practical Thermal Management Systems, David Ewing
An Investigation Of The Application Of Phase Change Materials In Practical Thermal Management Systems, David Ewing
All Dissertations
This work investigates the application of alternative cooling techniques to thermal management. In the first section, this work presents models and extensive simulation studies on an alternative cooling strategy based upon phase change materials (PCMs) for the thermal management system of a LED headlight assembly. These studies have shown that properly chosen PCMs, when suspended in metal foam matrices, increased the thermal conductivity of the PCM. The increased thermal conductivity can enhance the cooling characteristics of a practical thermal management system for a LED headlight system. To further enhance the advantages of using PCMs, nanoparticle enhanced fluids (nanofluids) are desirable …
Optimization-Based Power Management Of Hybrid Power Systems With Applications In Advanced Hybrid Electric Vehicles And Wind Farms With Battery Storage, Hoseinali Borhan
Optimization-Based Power Management Of Hybrid Power Systems With Applications In Advanced Hybrid Electric Vehicles And Wind Farms With Battery Storage, Hoseinali Borhan
All Dissertations
Modern hybrid electric vehicles and many stationary renewable power generation systems combine multiple power generating and energy storage devices to achieve an overall system-level efficiency and flexibility which is higher than their individual components. The power or energy management control, ``brain' of these ``hybrid' systems, determines adaptively and based on the power demand the power split between multiple subsystems and plays a critical role in overall system-level efficiency. This dissertation proposes that a receding horizon optimal control (aka Model Predictive Control) approach can be a natural and systematic framework for formulating this type of power management controls. More importantly the …
A Formal Representation Of Mechanical Functions To Support Physics-Based Computational Reasoning In Early Mechanical Design, Chiradeep Sen
A Formal Representation Of Mechanical Functions To Support Physics-Based Computational Reasoning In Early Mechanical Design, Chiradeep Sen
All Dissertations
The lack of computational support to the conceptual phase of mechanical engineering design is well recognized. Function-based modeling and thinking is widely recommended in design texts as useful means for describing design concepts and using them in tasks such as solution search, problem decomposition, and design archival. Graph-based function structure models that describe a product as a network of transformative actions of material, energy, and information, are discussed as a potential tool for this purpose, but in the current state of the art, function structures are not formalized as a computational representation. Consequently, no computer tool exists with which a …
Development Of A Design Method To Reduce Change Propagation Effects, Prabhu Shankar
Development Of A Design Method To Reduce Change Propagation Effects, Prabhu Shankar
All Dissertations
ABSTRACT
This dissertation presents a design method to reduce engineering changes caused due to change propagation effect. The method helps designers to systematically plan a verification, validation, and test (VV&T) plan. The rationale behind such a method is founded on a well-accepted principle that a robust validation plan can reduce design changes. However, such method has not yet been developed in mechanical engineering domain, so a method from software engineering has been adopted and extended to address the limitations in the existing design evaluation tools.
Tools extensively used in industry, such as FMEA, and in academia have been reviewed to …
Fabrication Of Grooved Hollow Fiber Membrane For Nerve Regeneration: Process Modeling And Performance Evaluation, Jun Yin
All Dissertations
Nerve injury is a general but intractable disease in traumatic injuries, leading to a significant reduction of functions in the nervous system. Extensive efforts are made on nerve injury rehabilitation. Since the appropriate connections between neurons and their targets are necessary, guiding axonal outgrowth is an essential step for neuron outgrowth in nervous system development, functioning, and regeneration. Besides the direct surgical nerve connection, an artificial means of guiding nerve regeneration called nerve conduits is widely applied in nerve injury rehabilitation. The main function of nerve conduits is to bridge the nerve gap, to help regenerating axons across damaged regions …
An Early Warning Monitoring System For Cnc Spindle Bearing Failure, Andrew Werner
An Early Warning Monitoring System For Cnc Spindle Bearing Failure, Andrew Werner
All Theses
Equipment employed in a manufacturing environment must be able to operate as long as possible having as little downtime as possible. Therefore, maintenance is crucial in order to allow for the equipment to perform its designated tasks without failure, especially on critical systems. In a CNC machine, if the spindle fails, the machine is useless. Having the ability to detect spindle degradation to the point where a replacement spindle installation can be planned, via condition monitoring, is invaluable to a manufacturer who utilizes these types of machines.
An early warning monitoring system for CNC spindle bearing failure has been developed …
Product And Process Based Assembly Time Estimation In Engineering Design, Michael Miller
Product And Process Based Assembly Time Estimation In Engineering Design, Michael Miller
All Theses
This thesis presents the research and development of two assembly time estimation techniques for the automotive industry. Both of these techniques are capable of being implemented early in the product life-cycle of a vehicle and require information available in this phase. Currently, assembly time estimation is performed after production has begun and is a tedious manual process requiring hours of motion-time method studies for each assembly activity. The techniques proposed in this thesis can both be performed prior to the start of production and are capable of being performed automatically after the initial mapping.
The first assembly time estimation technique …
In Vitro Study Of Fluid Diodes In The Pulmonary Valve Position, John Porcher
In Vitro Study Of Fluid Diodes In The Pulmonary Valve Position, John Porcher
All Theses
Every year many people suffer from severe chronic pulmonary insufficiency. Problems that can be incurred include the valve becoming stenotic, where it inhibits antegrade flow, and incompetent, allowing retrograde flow. When either of these conditions occurs with great severity, it is often necessary for the native valve to be replaced. There are no acceptable, permanent solutions currently available for a pulmonary valve replacement. Previous research, based on regurgitant fraction and transvalvular gradient, has indicated that a fluid diode could possibly serve as a permanent valve replacement solution. This study investigated the effectiveness of a diode to reduce the workload of …
Fabrication And Characterization Of Multi-Functional Non-Spherical Particles Via Mechanical Deformation, Venkata Shilpa Varahagiri
Fabrication And Characterization Of Multi-Functional Non-Spherical Particles Via Mechanical Deformation, Venkata Shilpa Varahagiri
All Theses
Nanoparticles bridge the gap between bulk materials and molecules. They possess exciting but contrasting mechanical, chemical, magnetic and optical properties when compared to their bulk counterparts due to their shape and size. When the size of noble metal nanoparticles is reduced to less than the wavelength of light, the particles intensely absorb and scatter light at wavelengths that depend on the particle size, shape, and local dielectric environment due to Localized Surface Plasmon Resonance (LSPR) modes. Recently, plasmonic particles have been used in a wide variety of sensor and optical device applications including immunoassays and surface enhanced Raman spectroscopy substrates. …
Laminar Flame Speed Estimation From Experimental Data Using A Quasi-Dimensional Turbulent Flame Entrainment Combustion Simulation For Spark Ignition Engines, Akash Desai
All Theses
The goal of this research is to develop a thermodynamic simulation of spark-ignition engine combustion that uses a predictive burn-rate model. Previously done thermodynamic engine simulations in MATLAB are based on a specified burn rate model. Also, the effect of turbulence parameters on the rate of mass burn up is not considered. A predictive burn rate model is necessary to study the effect of different fuels on spark ignition engine combustion. The effect of laminar flame speed and turbulent intensity on combustion is difficult to assess experimental due to the difficulty in the measurement of these two variables. Thus, the …
Effect Of Relative Humidity And Temperature Control On In-Cabin Thermal Comfort State, Ali Alahmer
Effect Of Relative Humidity And Temperature Control On In-Cabin Thermal Comfort State, Ali Alahmer
All Dissertations
This dissertation discusses the effect of manipulating the relative humidity RH levels inside vehicular cabins on the thermal comfort and human occupants' thermal sensation. Three different techniques are used to investigate this effect. Firstly, thermodynamic and psychometric analyses are used to incorporate the effect of changing RH along with the dry bulb temperature on the human comfort window. Specifically, the study computes the effect of changing the relative humidity on the amount of heat rejected from the passenger compartment and the effect on occupants comfort zone. A practical system implementation is also discussed in terms of an evaporative cooler design. …
Electrokinetic Transport And Manipulation Of Particles In Curved Microchannels, Junjie Zhu
Electrokinetic Transport And Manipulation Of Particles In Curved Microchannels, Junjie Zhu
All Dissertations
The investigation of electrokinetic particle transport in confined microchannels has practical significances in a variety of applications ranging from traditional gel electrophoresis to electrokinetic microfluidics-based lab-on-a-chip devices. To date, however, studies on particle electrokinetics have been limited to primarily theoretical or numerical analyses in straight microchannels of simple geometries. Very little work has been done on electrokinetic particle motions in real microchannels which usually consist of one or multiple turns. This thesis is dedicated to the fundamental and applied studies of electrokinetic transport and manipulation of particles in various curved microchannels using a combined experimental, theoretical, and numerical method.
First, …
Computational-Analysis Assisted Introduction Of Friction Stir Welding Into Development Of Light-Weight High-Survivability Military Vehicles, Guruprasad Arakere
Computational-Analysis Assisted Introduction Of Friction Stir Welding Into Development Of Light-Weight High-Survivability Military Vehicles, Guruprasad Arakere
All Dissertations
High strength aluminum alloys with superior blast/ballistic resistance against armor piercing (AP) threats and with high vehicle light-weighing potential are being increasingly used as military-vehicle armor. Due to the complex structure of these vehicles, they are commonly constructed through joining (mainly welding) of the individual components. Unfortunately, these alloys are not very amenable to conventional fusion based welding technologies (e.g. Gas Metal Arc Welding (GMAW)) and in-order to obtain high-quality welds, solid-state joining technologies such as Friction Stir Welding (FSW) have to be employed. However, since FSW is a relatively new and fairly complex joining technology, its introduction into advanced …
Mixture Fraction Imaging Based On Photodissociation Spectroscopy And Two Photon Laser Induced Fluorescence, Yan Zhao
All Dissertations
The study of turbulent combustion calls for new diagnostics that can measure multidimensional mixture fraction under a wide range of flame conditions. A laser diagnostic technique based on photodissociation spectroscopy (PDS) is proposed to address this need. This thesis describes the concept of the PDS-based diagnostic, reports its experimental demonstration in a non-premixed jet flame, and assesses its performance and applicable range. The two-photon laser induced fluorescence (TPLIF) technique used in conjugate with the PDS is analyzed numerically in line and planar imaging configuration.
The new mixture fraction imaging technique is centered around the creative use of photodissociation (PD) for …
Multi-Length Scale Modeling Of The High-Pressure, Large-Strain, High-Strain-Rate Response Of Soda-Lime Glass, William Bell
Multi-Length Scale Modeling Of The High-Pressure, Large-Strain, High-Strain-Rate Response Of Soda-Lime Glass, William Bell
All Dissertations
Development of new transparent armor systems is essential for the protection of the current and future US armed forces, especially in light of the recent military operations The Operation Iraqi Freedom in Iraq and The Operation Enduring Freedom in Afghanistan. These conflicts have introduced a new military theater without a well-defined battle front and new types of threats (e.g. improvised explosive devices, IEDs). Development and modeling of new transparent armor systems for use in numerous applications from vehicle windows to face shields is a current area of thrust aimed at addressing the shortcomings of existing systems in order to better …
An Investigation Of The Effects Of Surfactant Monolayers On Natural Convection Heat Transfer And Evaporative Mass Transfer, Steven Bower
An Investigation Of The Effects Of Surfactant Monolayers On Natural Convection Heat Transfer And Evaporative Mass Transfer, Steven Bower
All Dissertations
Laboratory experiments are presented that reveal the effects of surfactant monolayers on natural convection heat transfer and evaporation from bodies of water; more specifically, the situation is studied where the bulk temperature of the water is greater than the temperature of the air so that evaporative convection occurs. Four sets of experiments were performed in a laboratory environment on insulated tanks of different widths and depths for the following surface conditions: 1) clean surface, 2) oleyl alcohol covered surface, 3) stearic acid covered surface, and 4) stearyl alcohol covered surface. An infrared (IR) camera was used to verify the existence …
Investigation Of Two-Phase Behavior In Capillary Evaporators With Liquid Core Visualization, Brian D'Entremont
Investigation Of Two-Phase Behavior In Capillary Evaporators With Liquid Core Visualization, Brian D'Entremont
All Dissertations
The Capillary Pumped Loop (CPL) and Loop Heat Pipe (LHP) are thermal management devices which are high performance derivatives of the conventional heat pipe. Both consist of a discrete evaporator containing a porous solid wick which is coupled via smoothed walled tubing to a condenser. In a CPL, fluid inventory is managed by a reservoir attached to the liquid line which is controlled in temperature. In an LHP, fluid inventory is managed passively by a compensation chamber which is integral to the evaporator.
In this study, a borescope was inserted into the liquid core and compensation chamber of LHP evaporators …
Modeling, Finite Element Analysis, And Optimization Of Non-Pneumatic Tire (Npt) For The Minimization Of Rolling Resistance, Mallikarjun Veeramurthy
Modeling, Finite Element Analysis, And Optimization Of Non-Pneumatic Tire (Npt) For The Minimization Of Rolling Resistance, Mallikarjun Veeramurthy
All Theses
Recently, the development of non-pneumatic tires (NPT) such as the Michelin Tweel is receiving increased attention due to potential advantages over pneumatic tires such as low mass, no run flat, good contact pressure distribution, and low rolling resistance (RR). This study focuses on the design of a NPT based on properties of vertical stiffness, contact pressure, and rolling energy loss. Using a finite element (FE) model, a parametric study is conducted to study the effect on vertical stiffness, contact pressure, and rolling resistance (RR) response considering three design variables: (1) thickness of the spokes, (2) the shear band thickness, and …
Constrained Layer Damping Of Honeycomb Composite Structures, Rohit Telukunta
Constrained Layer Damping Of Honeycomb Composite Structures, Rohit Telukunta
All Theses
Composite sandwich structures have replaced homogenous dense solids in many applications due to their advantages of high stiffness to weight ratio, and higher damping characteristics. Higher damping in engineering applications is desirable to reduce structural vibrations. The application of a viscoelastic layer between two thin face sheets gives rise to the concept of constrained layer damping which is an effective technique to achieve increased damping in engineering applications.
Honeycomb cellular structures are often used for the core in sandwich construction because of their low density and high stiffness properties. Regular honeycombs are defined by conventional hexagonal geometry, which gives rise …
A Priori Analysis Of Subgrid-Scale Heat Flux Vectors In High Pressure H2/O2 Mixing And Reacting Shear Layers, Ayse Korucu
A Priori Analysis Of Subgrid-Scale Heat Flux Vectors In High Pressure H2/O2 Mixing And Reacting Shear Layers, Ayse Korucu
All Theses
A Direct Numerical Simulation (DNS) database of supercritical, transitional H2/O2 mixing and reacting shear layers is analyzed in an a priori manner to obtain subgrid statistics relevant to Large Eddy Simulation (LES) engineering modeling. The DNS employs a real gas state equation, detailed chemistry, accurate property models, multicomponent, differential, and cross diffusion. The parallel simulations were conducted using eighth order central finite differencing in conjunction with a fourth order accurate Runge-Kutta time integration, on resolutions up to 135 million grid points, and used up to 2,016 processing cores. All simulations are for an ambient pressure of 100 atm and are …
Molecular Dynamics Study Of Particle Impact Induced Bond Breaking Of Single-Walled Carbon Nanotubes And Quality Factors Of Nanocomposite Structures, Puroorava Annapaneni
Molecular Dynamics Study Of Particle Impact Induced Bond Breaking Of Single-Walled Carbon Nanotubes And Quality Factors Of Nanocomposite Structures, Puroorava Annapaneni
All Theses
Part A
Injection of particles to the side wall of single-walled carbon nanotubes (SWCNT) has been employed for doping and storage of particles on SWCNTs. In addition, particle bombardment can be used to cut and modify graphene structures. While the collision of hydrogen atoms with SWCNTs has been extensively studied, collision dynamic behavior of heavy particles with SWCNTs has not been well understood. To facilitate a better understanding of the particle-SWCNT collision process, in this work, we study the impact of five noble gas atoms (He, Ne, Ar, Kr, Xe) with SWCNTs and investigate particle impact induced CNT bond breaking …
Computational Analysis Of The Dynamic Forces In Drive Train Components Of An Offshore Wind Turbines, Artem Korobenko
Computational Analysis Of The Dynamic Forces In Drive Train Components Of An Offshore Wind Turbines, Artem Korobenko
All Theses
Wind has good potential for contributing to the national energy supply. Offshore sites and deep sea locations can be especially attractive as the wind turbine market grows. In such places larger wind resources are available with reduced turbulence intensity and wind shear. In addition, visual impact along with noise aspects are reduced. Offshore siting requires greater attention to structural stability and endurance. Forces on drive train components, such as the bearing system, are not well understood.
This work presents the development a model that calculates dynamical forces in drive train components of off-shore wind turbines. The model of a 5MW …
Injection Molding Of Micro-Features, Manjesh Dubey
Injection Molding Of Micro-Features, Manjesh Dubey
All Theses
A method for creating regular arrays of surface features in the 10µm to 200µm range over large areas in metallic materials enables the use of treated surfaces on injection molds. This surface control is used for manufacturing products with controllable optical, tribological, heat transfer, and surface tension properties. However, the flow, filling, and solidification behavior of molten polymer at the micro scale is not well understood.
Therefore, the purpose of this study is to understand the formation of micro-structure on a polymer surface and derive a range of robust solutions for injection molding of these micro-featured surfaces. This study uses …
A Method For Evaluating Manufacturing Change In Engineering Design, Christopher Brooks
A Method For Evaluating Manufacturing Change In Engineering Design, Christopher Brooks
All Theses
Design changes are a frequent occurrence over the life of a product that may be initiated by an update to the product functionality, new customer needs, or generational improvements. The costs associated with these changes are undesirable, and are often times greatly inflated by additional, unanticipated changes that result from change propagating throughout the system. Propagation paths occur when an initiating change to a component necessitates subsequent changes to coupled components, as the change continues to propagate throughout the product architecture. The nature of this change propagation is challenging to characterize and accurately predict. To address this issue, a change …
Extracting Depth Information From Stereo Vision System, Using A Correlation And A Feature Based Methods, Mahmoud Abdelhamid
Extracting Depth Information From Stereo Vision System, Using A Correlation And A Feature Based Methods, Mahmoud Abdelhamid
All Theses
This thesis presents a new method to extract depth information from stereo-vision acquisitions using a feature and a correlation based approaches. The main implementation of the proposed method is in the area of Autonomous Pick & Place, using a robotic manipulator. Current vision-guided robotics are still based on a priori training and teaching steps, and still suffer from long response time.
The study uses a stereo triangulation setup where two Charged Coupled Devices CCDs are arranged to acquire the scene from two different perspectives. The study discusses the details of two methods to calculate the depth; firstly a correlation matching …
Understanding The Role Of Functions And Interactions In The Product Design, Raveesh Ramachandran
Understanding The Role Of Functions And Interactions In The Product Design, Raveesh Ramachandran
All Theses
Engineering designers often generate design concepts based on a functional understanding of the problem. Many engineering textbooks encourage designers to abstract the essential problem to a higher-level functional representation of the product and subsequently develop solutions to the functional needs. However, a functional perspective of design does not provide a complete view of what the product must do and how the product must interact with users and other parts. To address this, an alternative modeling approach has been developed to complement the traditional functional modeling approaches. Two such approaches include (1) activity modeling to capture the user actions from production …
Cfd Analysis Of The Under Hood Of A Car For Packaging Considerations, Sreekanth Reddy Gondipalle
Cfd Analysis Of The Under Hood Of A Car For Packaging Considerations, Sreekanth Reddy Gondipalle
All Theses
In recent years, there has been an increase in demand towards the improvement of car design for achieving better performance and increasing passenger comfort. Improving the design of individual components to meet the customer needs for improved vehicle performance alone is not enough. Interactions of these components with the surrounding components and their placement should also be investigated. Placement of these components in the under hood space forms a 3-Dimensional packaging problem. In the past, a multi objective optimization process was setup to determine the optimal placement of these components in the car under hood space. Three main objectives were …
A Priori Analysis Of Subgrid-Scale Pressure In High Pressure H2/O2 Mixing And Reacting Shear Layers, Zhiyuan Ma
A Priori Analysis Of Subgrid-Scale Pressure In High Pressure H2/O2 Mixing And Reacting Shear Layers, Zhiyuan Ma
All Theses
An a priori analysis of subgrid-scale pressure in high pressure combustion is carried out using three different flow fields obtained by direct numerical simulation (DNS). The simulations directly solve the Navier-Stokes equations of high pressure, transitional H2/O2 mixing and reacting shear layers employing a cubic Peng-Robinson real gas state equation. Detailed chemistry, multicomponent, differential, and cross diffusion are included. The results are analyzed to provide subgrid information relevant to Large Eddy Simulation (LES) of turbulent combustion. The analysis includes a detailed comparison of the actual filtered pressure with its corresponding form evaluated with the filtered primitive variables. …
Modeling And Finite Element Alaysis Of Fluid Structure Interaction In A Wind Energy Harvester, Bargav Cheruku
Modeling And Finite Element Alaysis Of Fluid Structure Interaction In A Wind Energy Harvester, Bargav Cheruku
All Theses
An energy harvesting system inspired by musicplaying harmonicas was developed for microwind power generation. The energy harvester uses flow-induced self-sustained oscillations of a piezoelectric beam embedded within a chamber to generate electric power. While the power generation capability of the energy harvester has been demonstrated previously, there is a lack of understanding behind the basic physics of the driving mechanism responsible for the self-sustained oscillations. In addition, the performance of the nonlinear multi-physics system with strong fluid and structure coupling depends on many physical and design parameters. A systematic study on the effects of these parameters is necessary for the …