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Full-Text Articles in Engineering
Optimization Of The Tool Path In A Robotic Environment, Mukund Venkatachari Narasimhan
Optimization Of The Tool Path In A Robotic Environment, Mukund Venkatachari Narasimhan
Mechanical and Aerospace Engineering Dissertations
The rising costs and demand coupled with shrinking energy generating resources has triggered the need for optimum use of energy resources, minimizing the overhead costs and maximizing the profits. Robots have been long touted as a fit replacement of human labor force in manufacturing sectors. Slowly there is increased presence of robots in automobile and electronic industries. Typically they are used for welding, painting, ironing, assembly, pick and place, inspection, and testing. Mass production, fulfilling the ever increasing demand, can be accomplished by robots because of their precision, speed of operation and high endurance capabilities. This dissertation comprises of two …
Enhancement Of Pool Boiling Heat Transfer Using Thermally-Conductive Microporous Coating Techniques, Joo Han Kim
Enhancement Of Pool Boiling Heat Transfer Using Thermally-Conductive Microporous Coating Techniques, Joo Han Kim
Mechanical and Aerospace Engineering Dissertations
The present research is an experimental study of the enhancement of boiling heat transfer using microporous coating techniques. The current research is divided into four major phases. During the first phase, the effects of different metal particle sizes in the coating compound for thermally non-conductive microporous coating on pool boiling performance of refrigerants and water are investigated. The test surfaces, solid copper blocks with 1-cm² base, were tested at atmospheric pressure in saturated FC-72, R-123, and water. Results showed that the surface treatment by non-conductive microporous coating significantly enhanced both nucleate boiling and critical heat flux of all three refrigerants. …
Computer-Aided Patient Specific Treatment Planning Of Cryosurgery For Breast Cancer, Junkyu Jung
Computer-Aided Patient Specific Treatment Planning Of Cryosurgery For Breast Cancer, Junkyu Jung
Mechanical and Aerospace Engineering Theses
Cryosurgery, which is to destroy tumors by use of localized freezing, is an emerging treatment modality for breast cancer as the size of detectable tumor becomes smaller due to more frequent use of various diagnostic imaging including MRI, CT and mammogram. Although general surgical guideline has been developed and its effectiveness has been demonstrated, cryosurgical protocol should be adjusted for a given patient to accommodate patient-specific variations including tumor size, location and geometry of patient's breast. In this study, a computerized treatment planning tool was developed to aid surgeons to determine surgical parameters considering patient specific diagnostic information. This tool …
Finite Element Modeling Of Carbon Nanotube Reinforced Polymer Composites And Evaluating Its Thermal Conductivities, Raghuram Basavanahalli
Finite Element Modeling Of Carbon Nanotube Reinforced Polymer Composites And Evaluating Its Thermal Conductivities, Raghuram Basavanahalli
Mechanical and Aerospace Engineering Theses
High thermal conductivity of carbon nanotubes has motivated us to study and understand the thermal mechanisms in nanocomposites. Though several theoretical models predict a high thermal conductivity for CNT reinforced polymer composites, the experimental validation are not so encouraging. A finite element model of MWNT reinforced nanocomposite is developed based on continuum mechanics approach. The finite element model is a representative volume element (RVE) with single MWNT inclusion. The inclusion is modeled based on the continuum model of MWNT as effective solid fiber [22].The interface resistance between the nanotube and the matrix material is modeled using thermal contact elements. The …
Freezing-Induced Microstructural Changes Of Collagen Scaffolds, Jeffrey David Miller
Freezing-Induced Microstructural Changes Of Collagen Scaffolds, Jeffrey David Miller
Mechanical and Aerospace Engineering Theses
Understanding the effects of freezing on the functional properties of tissues is critical to cryopreservation of native and artificial tissues, and prognosis after cryotherapies. Although investigations have been performed to correlate macroscopic properties such as mechanical properties with freezing parameters, the effects are typically tissue-type dependent and no physical understanding is available to explain these effects. Since the mechanical and optical properties of a tissue are based on the characteristics of its extracellular matrix (ECM), understanding and quantifying these changes could assist in predicting the response a tissue will have to freezing under different circumstances. In this study, the microstructural …
Design And Optimization Of Heat Spreaders And Selection Of Fan In Laptop, Kranthi Kumar Manne Sambaiah
Design And Optimization Of Heat Spreaders And Selection Of Fan In Laptop, Kranthi Kumar Manne Sambaiah
Mechanical and Aerospace Engineering Theses
Technical advancements lead to the need for faster processors and reduced sizes in electronic systems. The urge for faster and compact systems leads to two major problems. Firstly over heating of chips which degrade the chip performance and secondly formation of heat spots on the surface which makes the user uncomfortable. Thermal management engineers, as a result have a major challenge in improving the cooling systems. In this research project simulation using the thermal modeling tool selected is Icepak. The prototype model of the laptop is designed, boundary conditions are applied and analysis is done. The results so obtained in …
Multi-Sensor Fusion Based Control For Autonomous Operations: Rendezvous And Docking Of Spacecraft, Jonathan Bryan Mcdonald
Multi-Sensor Fusion Based Control For Autonomous Operations: Rendezvous And Docking Of Spacecraft, Jonathan Bryan Mcdonald
Mechanical and Aerospace Engineering Theses
The project considers the problem of motion synchronization of free flying robotic spacecraft and serviceable floating objects in space. The synchronization maneuvers are based on sample and hold nonlinear translational and attitude control laws. GPS pseudorange signals and a vision based sensor unit are modeled to give position measurements; position and velocity estimates are extracted from the measurements based on Extended Kalman Filter models. A sensor data fusion algorithm in the form of a Federated Extended Kalman Filter is implemented that blends the estimates of the individual filters into a global estimate. Nonlinear simulations where a Pursuer spacecraft attempted to …
Flexible Microfluidic Circuit With Embedded In-Plane Valve, Srikar C. Paruchuri
Flexible Microfluidic Circuit With Embedded In-Plane Valve, Srikar C. Paruchuri
Mechanical and Aerospace Engineering Theses
Recent developments in Microfluidic systems have demonstrated many potential applications related to biology, chemistry and medical sciences. Fluidic manipulation with precise volume control is a basic function in these systems, and microvalves play an important role in control and delivery of the fluid sample. One of the key issues in such valve design is to make large membrane deflections compared to the channel dimension. This thesis reports a flexible microfluidic chip with embedded in-plane valves for fluid manipulation. Silicone elastomer (Polydimethylsiloxane - PDMS) is one of the most suitable materials to fabricate microvalve membranes, because of its low Young's modulus, …
Structural Analysis Of Fiber Reinforced Composite Materials, Cesar Augusto Rojas
Structural Analysis Of Fiber Reinforced Composite Materials, Cesar Augusto Rojas
Mechanical and Aerospace Engineering Theses
A study of fiber reinforced composite structures is conducted .This study includes laminate analysis, analysis of laminated composite beams and parametric study of composite beams. Finite element analysis for each beam model is conducted to verify the results obtained by analytical model. The analysis of the laminated beams in this study covers: 1. beam with a solid rectangular cross-section subjected to a transverse load 2. beam with a I-section under bending 3. beam with a squared tubular section under bending 4. beam with truss section under bending One of the principal purposes of this thesis is to create a user …
Thermal Enhancement Of Stacked Dies Using Thermal Vias, Baekyoung Sung
Thermal Enhancement Of Stacked Dies Using Thermal Vias, Baekyoung Sung
Mechanical and Aerospace Engineering Theses
Following Moore's law, the number of transistors on a die continues to rise and has recently exceeded a billion on high end processors. In light of the convergence of technology, power requirements is becoming a serious concern even on low density interconnect systems such as cellular phones and personal digital assistants. Also, in order to minimize foot prints, the recent trend in packaging is stacking. The stacking, however, creates challenges in cooling and especially if one is to include logic in the stack. The primary heat flow path for stacking is through the substrate and as the number of stacks …
Analysis And Optimal Design Of Beams Using Radial Basis Function, Yung-Kang Sun
Analysis And Optimal Design Of Beams Using Radial Basis Function, Yung-Kang Sun
Mechanical and Aerospace Engineering Dissertations
The application of Multiquadric Radial Basis Function (MQ RBF) in the analysis and optimal design of beams are addressed in this dissertation. For static analysis, a new Least Square Collocation (LSC) method is introduced. For buckling and vibration analysis, Rayleigh-Ritz analysis procedures are presented using MQ RBF basis function. Numerical results show that LSC can provide better results than the classical collocation method when the same number of collocation points are used. In vibration analysis, MQ RBF-based Rayleigh-Ritz can be used to calculate natural frequency accurately for several hundred modes. The important question of choosing shift parameters is discussed and …
Mems Packaging: Fluxless Soldering And Reliability Assessment, Amit L. Patil
Mems Packaging: Fluxless Soldering And Reliability Assessment, Amit L. Patil
Mechanical and Aerospace Engineering Theses
This thesis presents process development and reliability assessment of the fluxless packaging of the MEMS devices. This packaging consists of metallized Kovar package with side wall of same material and circular holes for the optical fiber interconnect between the microstructures on the chip and the macro-environment. The back of the MEMS chip and the soldering part of the optical fiber is metallized. A thin solder perform is placed between the chip and the metallized package to attach the chip and a circular solder perform is used to attach the fiber to the metal substrate. The soldering process is fluxless hence …
Spacecraft Formation Flight: Analysis Of The Perturbed J2-Modified Hill-Clohessy-Wiltshire Equations, Jeffery Scott Ginn
Spacecraft Formation Flight: Analysis Of The Perturbed J2-Modified Hill-Clohessy-Wiltshire Equations, Jeffery Scott Ginn
Mechanical and Aerospace Engineering Theses
With the recent technological gains made in satellite design and manufacturing, there has been great interest in utilizing a cluster of satellites to perform the same tasks performed by larger satellites. Historically, this has been done utilizing the Clohessy-Wiltshire equations, or the Hill's equations, as a benchmark for understanding the physics of the relative motion between two spacecraft. A variety of different models have been derived and implemented to study the relative motion dynamics since the Hill-Clohessy-Wiltshire (HCW) equations. Some of these models, like the HCW equations, are linearized and have analytical solutions. These models make the underlying physics due …
Uncertainty Characterization Of Orbital Debris, Jolanta Matusewicz
Uncertainty Characterization Of Orbital Debris, Jolanta Matusewicz
Mechanical and Aerospace Engineering Theses
The increase of orbital debris in the low Earth orbit is a concern for the space industry. Spacecraft and satellites are at risk of collision with orbital debris. Collisions can damage sensitive components or result in catastrophic failure. Organizations such as the United States Space Command are responsible for tracking orbital debris using ground based sensor sites located around the world. Orbit determination techniques are used to estimate the position and velocity of the orbit using range, azimuth, and elevation measurements obtained from the sensors. Nine sensors from the Space Surveillance Network are simulated to track a debris object in …
Parameters Affecting Critical Heat Flux Of Nanofluids: Heater Size, Pressure Orientation And Anti-Freeze Addition, Madhav Rao Kashinath
Parameters Affecting Critical Heat Flux Of Nanofluids: Heater Size, Pressure Orientation And Anti-Freeze Addition, Madhav Rao Kashinath
Mechanical and Aerospace Engineering Theses
This research aims at investigating the effect, heater size, pressure, heater orientation and effect of anti-freeze addition on critical heat flux of nanofluids which have shown large potentials as coolants for high power generating uses. Nanofluids have shown about ~180 - 200% enhancement in the critical heat flux values. The effect of heater size employing three different sized heaters yielded about ~180% enhancement over pure water. The effect of pressure on critical heat flux investigated by testing nanofluids at three pressures showed ~240% increase in critical heat flux. Surface orientation effect on critical heat flux carried out for a 2 …
Effect Of Crac Location On A Fixed Rack Layout Of A Data Center, Vishwas Bedekar
Effect Of Crac Location On A Fixed Rack Layout Of A Data Center, Vishwas Bedekar
Mechanical and Aerospace Engineering Theses
Microprocessor driven escalation of thermal management needs has resulted in significant cooling challenges at the data center facility level, which can house thousands and tens of thousands of heat producing processors. Raised floor air ducting is the most common configuration, where chilled air from the air conditioning units is forced into the room via a under floor plenum and through perforated tiles on the floor. The hot air from the racks finds its way to the top of the air conditioning units and is then cooled and blown into the under floor plenum. The temperature at inlet of the racks …
Enhancement Of Cryoinjury By Use Of Eutectic Crystallization Of An Amino Acid Adjuvant, Chuo-Li Wang
Enhancement Of Cryoinjury By Use Of Eutectic Crystallization Of An Amino Acid Adjuvant, Chuo-Li Wang
Mechanical and Aerospace Engineering Theses
Enhancement of cryoinjury by use of eutectic formation was investigated to improve the efficacy of cryosurgery. Although the enhancement of cryoinjury associated with eutectic crystallization of sodium chloride (NaCl) has been demonstrated, its advantage can be maximized with adjuvants which are biocompatible and have higher eutectic temperature than NaCl. In this study, the feasibility of glycine, which is less toxic and have higher eutectic temperature than NaCl, was tested. Two groups of MCF-7 human breast cancer cell were suspended in isotonic saline with glycine, then were frozen and thawed on a directional solidification stage in the same protocol except that …
Development Of Three Block Thermal Compact Model And Verification Of Modified Linear Superposition Technique For Stacked Die, Suresh G. Nikalaje
Development Of Three Block Thermal Compact Model And Verification Of Modified Linear Superposition Technique For Stacked Die, Suresh G. Nikalaje
Mechanical and Aerospace Engineering Theses
Over the last few years an impressive amount of progress has been achieved in the field of compact modeling of chip packages. But available compact modeling methods could not address the issue of limitation on the mesh statistics which is major concern while modeling in FEM softwares with limited number of nodes and elements. It is not possible to attain convergence of solution for thermal simulation of detailed model with the constraint on the number of nodes and elements. In this thesis, a simple and straight forward three block (3B) compact modeling method is developed. 3B compact modeling method has …
Analysis And Design Of A Piezoelectric Micro-Actuator, Po-Shiun Chen
Analysis And Design Of A Piezoelectric Micro-Actuator, Po-Shiun Chen
Mechanical and Aerospace Engineering Theses
Micro-grippers are usually fabricated of silicon using traditional semiconductor manufacturing processes and actuated based on thermal energy input causing their temperature to substantially increase and render unsuitable for certain applications such as biological tissue handling. In this research work, the design of a micro-gripper using piezoelectric ceramics (PZT) is presented as an alternative to silicon based micro gripper. The design procedure utilized ANSYS, a Finite Element Method based software tool to verify simple PZT models and subsequently evaluate the stroke for a family of configurations. The configurations were further explored and optimized considering that the fabrication would be performed using …
Crashworthiness Design Optimization Using Surrogate Models, Cheng-Ho Tho
Crashworthiness Design Optimization Using Surrogate Models, Cheng-Ho Tho
Mechanical and Aerospace Engineering Dissertations
Despite the advances in computer technology, the enormous computational cost associated with the large-scale and complex nonlinear crashworthiness simulations renders it to be impractical to rely exclusively on computer simulations for crashworthiness design optimization. A preferable strategy is to employ the computational efficient surrogate model in lieu of the expensive simulations to facilitate the optimization process and design concept exploration. An added advantage of the surrogate models is that they tends to eliminate the high-frequency numerical noise which may hinder the performance of the direct gradient-based optimization technique by constructing smooth crash responses in the crashworthiness analysis. Even thought the …
Structural Optimization Using Femlab And Smooth Support Vector Regression, Divija Odapally
Structural Optimization Using Femlab And Smooth Support Vector Regression, Divija Odapally
Mechanical and Aerospace Engineering Theses
In recent years support vector machine (SVM) has been emerging as a popular tool for function approximation. Application of SVM for approximation of mathematical functions and complex engineering analysis has been represented by Palancz et al and Clarke et al, respectively. However the training of the original SVM involves the solution of a quadratic programming (QP) problem. This makes the application of SVM to large problem computationally expensive. To circumvent this difficulty, Lee et al developed a more efficient SVM formulation namely epsilon-SSVR which drastically improved the training efficiency of SVM. In this research the SSVR is used to build …
Frequency Response Approximation Methods Of The Dissipative Model Of Fluid Transmission Lines, John King
Frequency Response Approximation Methods Of The Dissipative Model Of Fluid Transmission Lines, John King
Mechanical and Aerospace Engineering Theses
This thesis introduces an accurate and efficient method of obtaining a linear approximation for a nonlinear model of a complete fluid transmission line system using Matlab® Signal Processing Toolbox and Symbolic Math Toolbox programs. This technique is then packaged in a Graphical User Interface program to streamline the process of analyzing a total system. The method of approximating the frequency response of a fluid transmission line with a rational polynomial transfer function using the Matlab® 'invfreqs' least squares curve fitting algorithm has already been introduced. This research improves the technique by applying the 'invfreqs' command to a total system rather …
Finite Element Analysis Of Moisture And Thermal Induced Stress In Flip Chip Packages, Santanu Ghosh
Finite Element Analysis Of Moisture And Thermal Induced Stress In Flip Chip Packages, Santanu Ghosh
Mechanical and Aerospace Engineering Theses
The process of moisture absorption and subsequent hygroswelling stress development is a cause of concern in the IC packaging industry. Also thermal stresses developed during the lead free reflow process with a high peak temperature (~ 250oC) add to the problem. In Flip Chip packages, the related effects are high shear stresses at the multilayer interfaces and normal stresses in solder balls. This can lead to phenomenon like delamination at the interfaces and UBM opening. In this work we have made an attempt to simulate the moisture absorption process, subsequent hygroswelling stress development, and thermal stress generated during reflow using …
Air Jet Impingement For Levitation, James Frederick Huber
Air Jet Impingement For Levitation, James Frederick Huber
Mechanical and Aerospace Engineering Theses
Traditional part acquisition methods such as vacuum cups and robotic grippers do not meet the handling needs of truly fragile materials, because both of these methods require surface contact. An alternative to these traditional approaches is the use of air jet impingement for levitation. This technique confines impinged air to a thin disk above the target to form radial diffuser. The Bernoulli Effect causes a pressure difference between the fast-moving impinged air above the surface and ambient air below it. The net pressure difference is sufficient to lift objects weighing more than one kilogram using standard shop air. This method …
Numerical Study On Capillarity- Dominant Free Surface And Interfacial Flows, Zhaoyuan Wang
Numerical Study On Capillarity- Dominant Free Surface And Interfacial Flows, Zhaoyuan Wang
Mechanical and Aerospace Engineering Dissertations
The continuum surface force (CSF) method has been extensively employed in the volume-of-fluid (VOF), level set (LS) and front tracking methods to model surface tension forces. Its ability is limited for the surface tension dominant free surface and interfacial flows due to the existence of spurious currents. These currents may lead to disastrous interface instabilities and failure of grid convergence, which are present in all the previous versions of the CSF algorithm. In this study, a coupled level set and volume-of-fluid method (CLSVOF) is employed for interface tracking, which offers more accurate computations of the curvature and the normal vector …
Viscoplastic Finite-Element Simulation To Predict The Solder Joint Fatigue Life Of Different Flash Memory Die Stacking Architectures, Yong Je Lee
Mechanical and Aerospace Engineering Theses
This thesis focuses on the viscoplastic finite-element simulation to predict the solder joint fatigue life of different die stacking architectures for flash memory products. Four different stacked package architectures were evaluated as follows: pyramid, rotated, and spacer stacking, while interconnection (solder joint) was held constant. Number of dies for all four stacking configurations were varied from three, five and seven. To keep the package height constant, the die and die attach thickness were varied and the resulting effects on the stresses were investigated. A quarter and half symmetry model of stacked flash package are generated using ANSYS APDL script. The …
Active Flow Control Of Low Pressure Turbine Blade Separation Using Plasma Actuators, Karthik Ramakumar
Active Flow Control Of Low Pressure Turbine Blade Separation Using Plasma Actuators, Karthik Ramakumar
University of Kentucky Master's Theses
The current study examines plasma actuators as flow control devices. The actuators are placed on a turbine blade profile in a 2D turbine cascade for separation flow control. The configuration involves copper strips separated by a layer of dielectric material, across which an AC electric potential in the range of 5 kHz and 5 kV is applied. The efficiency of the actuator is monitored by measuring power input and flow control effectiveness. Preliminary observations are performed for a quiescent case on a flat plate profile to analyze the average and instantaneous velocities generated by the actuator for varied input parameters, …
Heat And Mass Transfer (Baehr And Stephan), Dr Alireza Zolfaghari
Heat And Mass Transfer (Baehr And Stephan), Dr Alireza Zolfaghari
Dr Alireza Zolfaghari
No abstract provided.
A Heat Transfer Textbook (Lienhard), Dr Alireza Zolfaghari
A Heat Transfer Textbook (Lienhard), Dr Alireza Zolfaghari
Dr Alireza Zolfaghari
No abstract provided.