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Articles 1 - 17 of 17
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 …
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
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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 …
Implementation Of Delayed-Feedback Controllers On Continuous Systems And Analysis Of Their Response Under Primary Resonance Excitations, Yousef Qaroush
Implementation Of Delayed-Feedback Controllers On Continuous Systems And Analysis Of Their Response Under Primary Resonance Excitations, Yousef Qaroush
All Dissertations
During the last three decades, a considerable amount of research has been directed toward understanding the influence of time delays on the stability and stabilization
of dynamical systems. From a control perspective, these delays can either have a compounding and destabilizing effect, or can actually improve controllers'
performance. In the latter case, additional time delay is carefully and deliberately introduced into the feedback loop so as to augment inherent system delays and
produce larger damping for smaller control efforts. While delayed-feedback algorithms have been successfully implemented on discrete dynamical systems with
limited degrees of freedom, a critical issue appears in …
High Resolution Vision-Based Servomechanism Using A Dynamic Target With Application To Cnc Machines, Carlos Montes-Solano
High Resolution Vision-Based Servomechanism Using A Dynamic Target With Application To Cnc Machines, Carlos Montes-Solano
All Dissertations
This dissertation introduces a novel three dimensional vision-based servomechanism with application to real time position control for manufacturing equipment, such as Computer Numerical Control (CNC) machine tools. The proposed system directly observes the multi-dimensional position of a point on the moving tool relative to a fixed ground, thus bypassing the inaccurate kinematic model normally used to convert axis sensor-readings into an estimate of the tool position.
A charge-coupled device (CCD camera) is used as the position transducer, which directly measures the current position error of the tool referenced to an absolute coordinate system. Due to the direct-sensing nature of the …
Fluid Dynamics Of Cell Printing, Ping He
Fluid Dynamics Of Cell Printing, Ping He
All Dissertations
Cell printing is an emerging technology that uses droplets to deliver cells to desired positions with resolution potentially comparable to the size of single cells. In particular, ink–jet based cell printing technique has been successfully used to build simple bio–constructs and has shown a promise in building complex bio–structures or even organs. Two important issues in ink–jet based cell printing are the moderate survival rate of delicate cells and the limited cell placement resolution. Resolving these issues is critical for the ink–jet based cell printing techniques to realize their full potential.
In this work, we use numerical simulations to reconstruct …
A Methodology For The Analysis Of In-Vehicle Operating Data And Design Of Intelligent Vehicle Systems For Improved Automotive Safety, Matthew Jensen
A Methodology For The Analysis Of In-Vehicle Operating Data And Design Of Intelligent Vehicle Systems For Improved Automotive Safety, Matthew Jensen
All Dissertations
Every year global motorization increases as more motor vehicles are manufactured, and the total number of vehicle miles traveled rises. These increased travel opportunities result in higher numbers of injuries, fatalities, and monetary losses associated with traffic-related crashes. In the last decade, hundreds of thousands of people were killed by vehicle collisions in the United States. The World Health Organization has labeled traffic crashes as the ninth leading cause of global disease; by the year 2020, traffic crashes are expected to rise to number three. An opportunity exists to improve global human safety through research and innovation in driver training …