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Articles 781 - 810 of 962

Full-Text Articles in Mechanical Engineering

Development Of An Experimental And Analytical Model Of An Active Cooling Method For High-Power Three-Dimensional Integrated Circuit (3d-Ic) Utilizing A Multidimensional Configured Thermoelectric Modules, Huy Phan Jan 2011

Development Of An Experimental And Analytical Model Of An Active Cooling Method For High-Power Three-Dimensional Integrated Circuit (3d-Ic) Utilizing A Multidimensional Configured Thermoelectric Modules, Huy Phan

Mechanical and Aerospace Engineering Dissertations - Archive

An increase in demand for more functionality and capacity of microelectronic components within the same logistic footprint drives the growth of three-dimensional integrated circuit (3D-IC) packaging technologies in recent years. However, the reduction in size and an increase in transistors density also intensified the heat flux of stacked-dice, which introduces many thermal challenges at both the package and cooling levels. Traditional passive cooling system such as forced air convection cooling, phase change materials and passive or active heat sinks will become inadequate to cool future processors and cannot accommodate the demand of future sub-ambient cooling of 3D-ICs. Within the past …


Hybrid Dynamic Simulation For Performance Optimization Of Legged Mechanisms, Daniel Montrallo Flickinger Jan 2011

Hybrid Dynamic Simulation For Performance Optimization Of Legged Mechanisms, Daniel Montrallo Flickinger

Mechanical and Aerospace Engineering Dissertations - Archive

Agile locomotion is needed for mobile robots to efficiently navigate challenging terrain. The ability of an agile legged mobile robot to abruptly change trajectory allows it toquickly react to obstacles and successfully operate in environments usually more suited forlegged animals. The research presented herein aims to increase the agility and performanceof legged robots.Using hybrid dynamic simulation, novel methods are developed to model the inter-action of a legged robot with the ground. In considering robot agility, an accurate model ofthe events that occur while in contact is needed. Methods are developed to model groundinteraction where oblique angled impacts occur, and to …


Design And Modeling Techniques For Cooling Of Telecommunication Systems, Naveen Kannan Jan 2011

Design And Modeling Techniques For Cooling Of Telecommunication Systems, Naveen Kannan

Mechanical and Aerospace Engineering Theses - Archive

Conventional data centers are extremely large buildings that have complex power distribution and cooling systems. These traditional brick and mortar data centers employ relatively expensive cooling systems and are inefficient. It has in turn led to an increase in construction and operational costs. These inefficiencies of traditional data centers can be overcome by partitioning the server load into modular sections which can be deployed, powered and cooled depending on availability and requirement. Furthermore, improvements in efficiency and operational costs can be achieved by employing "free cooling" to cool the IT equipment. Free cooling involves the introduction of outside air through …


Design Optimization Of A Wind Turbine Blade, Bharath Koratagere Srinivasa Raju Jan 2011

Design Optimization Of A Wind Turbine Blade, Bharath Koratagere Srinivasa Raju

Mechanical and Aerospace Engineering Theses - Archive

This work focuses on designing a blade of 45 meters in length that produces a power of 1.6 MW. The design of the blade was done using the Blade Element Momentum theory and the Prandtl's tip loss factor was used. The aerodynamic loads and differential power at are tabulated and plotted.The finite element method for analysis of the blade is used. As the chord lengths vary decreasingly along the blade radii in order to use the simple beam theory the breath and height of the blade is considered as a function of the chord length, hence the analysis is done …


Filling Of Methane/Air Mixture In A Tube For Pulse Detonation Engines, Shravani Dwarakapally Jan 2011

Filling Of Methane/Air Mixture In A Tube For Pulse Detonation Engines, Shravani Dwarakapally

Mechanical and Aerospace Engineering Theses - Archive

In pulse detonation engines, filling is a time consuming process; reducing these times will help to increase the frequency. The filling of a detonation tube, 1 m long tube with an internal diameter of 101.6 mm, closed at one end and opened at the other, was studied using the unsteady flow solver methane and air nominally at STP· Three cases were examined: (i) a 25.4 mm diameter port at the center of the closed end, (ii) nine ports of 25.4 mm diameter, one at the center of the closed end and eight distributed in two diametrically opposite rows, equally, four …


Control Of Airship Motion In The Presence Of Wind, Jatuporn Nakpiam Jan 2011

Control Of Airship Motion In The Presence Of Wind, Jatuporn Nakpiam

Mechanical and Aerospace Engineering Theses - Archive

This research effort develops a guidance and control system for a small airship to fly through assigned waypoints in the three dimensional space with a desired speed in the presence of wind and wind gust. In the control system development and validation, a simulation environment based on the nonlinear 6-DOF model of an airship, including the effect of the wind, is used. The airship has five control variables, the main thrust, the main thrust angle, the tail thrust, elevator and rudder deflections. The effectiveness of the elevator and rudder degrades as the speed of the airship decreases. The controller design …


Parametric Analysis Of A Detonation-Type Turbofan, Yashwanth M. Swamy Jan 2011

Parametric Analysis Of A Detonation-Type Turbofan, Yashwanth M. Swamy

Mechanical and Aerospace Engineering Theses - Archive

A new type of turbofan which detonates a fuel-air mixture was theoretically found to perform better than a conventional turbofan. A continuous detonation process is described and considered inside the core of the turbofan. The detonation-type turbofan needs certain modifications to detonate the fuel-air mixture at the core of the turbofan, namely, an annular detonation chamber to achieve continuous detonation. A parametric analysis of the new detonation-type turbofan was developed and used to calculate the performance parameters.


Numerical Study Of Drop Formation From Dripping To Jetting, Allouah Kadjo Jan 2011

Numerical Study Of Drop Formation From Dripping To Jetting, Allouah Kadjo

Mechanical and Aerospace Engineering Theses - Archive

The formation of liquid droplet from a capillary tube has been examined using numerical simulations. The dimensions of the capillary tube and the flow velocity have been varied to observe the regimes of drop formation. There are three main regimes of drop formation, which are the periodic dripping, the dripping faucet and the jetting regimes. The mechanism of drop formation changes from one regime to another and involves different parameters. A particular emphasis has been placed on the velocity limits between the different regimes and the critical role played by instabilities in the generation of satellite drops. The algorithm used …


Numerical Modeling Of A Parallel Plate Electrowetting-On-Dielectric (Ewod) Device, Kevin Tully Jan 2011

Numerical Modeling Of A Parallel Plate Electrowetting-On-Dielectric (Ewod) Device, Kevin Tully

Mechanical and Aerospace Engineering Theses - Archive

Numerical modeling and simulations have been performed in this study that focuses on modeling the fluid dynamics of an Electrowetting-on-Dielectric (EWOD) device. The case to be modeled in the present study is a droplet cutting problem where a droplet is sandwiched between two plates of Teflon and an electrical actuation will cause the droplet to cut or split into two smaller droplets. A finite difference method has been used to solve the Navier-Stokes equations, along with the continuity equation. An algorithm used for tracking the free surface is the Volume of Fluid (VOF) method. Along with using the VOF method …


Heat Transfer In Triangular Ducts With Axial Conduction,Containing Porous Medium, Abhishek Banerjee Jan 2011

Heat Transfer In Triangular Ducts With Axial Conduction,Containing Porous Medium, Abhishek Banerjee

Mechanical and Aerospace Engineering Theses - Archive

The objective of this study is to find a numerical solution for the velocity and temperature field in a duct of triangular cross-section area. A fully saturated porous medium is considered to be present in the duct. The study reports the contribution of axial conduction in heat transfer to flow passing through triangular porous passages. The terms in x-direction are retained in the energy equation due to the presence of axial conduction. Also, because of the geometrical asymmetry, non-orthogonal boundary conditions can exist and thus make the determination of heat transfer more difficult. The problem under consideration uses H2 boundary …


Nonlinear Finite Element Analysis Of Columns, Rajkiran Muppavarapu Jan 2011

Nonlinear Finite Element Analysis Of Columns, Rajkiran Muppavarapu

Mechanical and Aerospace Engineering Theses - Archive

In many engineering applications structural components are considered to be beams or columns subjected to a range of external loads such as dead weight, wind, temperature changes etc.In this work a mathematical model has been developed for a sports lighting tower considering it to be a cantilever beam with large deformation. The concept of non-linear P-Delta analysis is applied to the column. Using this model, a tower analysis tool was developed in MATLAB. Using this tool various design alternatives can be examined to evaluate their suitability to a particular task.A number of example problems from the available literature were solved …


Stable Reference Trajectory Modification For Handling Actuator Failure In Control Systems, Ifeolu Olalekan Ogunleye Jan 2011

Stable Reference Trajectory Modification For Handling Actuator Failure In Control Systems, Ifeolu Olalekan Ogunleye

Mechanical and Aerospace Engineering Theses - Archive

The issue of rapidly reconfiguring the reference trajectory under unanticipated actuator failures in order to regain lost performance or aircraft handling qualities is explored. The failures detected in real-time are compensated for by ensuring the input to the system reflects current system conditions. This thesis will also show that only the general structure of the failed system component is needed to achieve successful failure detection and reference trajectory reconfiguration. This approach allows the nominal control structure to remain unchanged in the presence of change flight and system conditions. Acceptable system performance is recovered by detecting the actuator failures in real-time. …


Aircraft Conceptual Design - An Adaptable Parametric Sizing Methodology, Gary John Coleman Jan 2010

Aircraft Conceptual Design - An Adaptable Parametric Sizing Methodology, Gary John Coleman

Mechanical and Aerospace Engineering Dissertations - Archive

Aerospace is a maturing industry with successful and refined baselines which work well for traditional baseline missions, markets and technologies. However, when new markets (space tourism) or new constrains (environmental) or new technologies (composite, natural laminar flow) emerge, the conventional solution is not necessarily best for the new situation. Which begs the question "how does a design team quickly screen and compare novel solutions to conventional solutions for new aerospace challenges?" The answer is rapid and flexible conceptual design Parametric Sizing. In the product design life-cycle, parametric sizing is the first step in screening the total vehicle in terms of …


Constrained Dynamics Approach For Motion Synchronization And Consensus, Divya Bhatia Jan 2010

Constrained Dynamics Approach For Motion Synchronization And Consensus, Divya Bhatia

Mechanical and Aerospace Engineering Theses - Archive

In this research we propose to develop constrained dynamical systems based stable attitude synchronization, consensus and tracking (SCT) control laws for the formation of rigid bodies. The generalized constrained dynamics Equations of Motion (EOM) are developed utilizing constraint potential energy functions that enforce communication constraints. Euler-Lagrange equations are employed to develop the non-linear constrained dynamics of multiple vehicle systems. The constraint potential energy is synthesized based on a graph theoretic formulation of the vehicle-vehicle communication. Constraint stabilization is achieved via Baumgarte's method. The performance of these constrained dynamics based formations is evaluated for bounded control authority.The above method has been …


Ideal Cycle Analysis Of A Regenerative Pulse Detonation Engine For Power Production, Rafaela Bellini Jan 2010

Ideal Cycle Analysis Of A Regenerative Pulse Detonation Engine For Power Production, Rafaela Bellini

Mechanical and Aerospace Engineering Dissertations - Archive

Over the last few decades, considerable research has been focused on pulse detonation engines (PDEs) as a promising replacement for existing propulsion systems with potential applications in aircraft ranging from the subsonic to the lower hypersonic regimes. On the other hand, very little attention has been given to applying detonation for electric power production. One method for assessing the performance of a PDE is through thermodynamic cycle analysis. Earlier works have adopted a thermodynamic cycle for the PDE that was based on the assumption that the detonation process could be approximated by a constant volume process, called the Humphrey cycle. …


Stress Analysis Of Laminated Composite Beam With I-Section, Jitesh Cherukkadu Parambil Jan 2010

Stress Analysis Of Laminated Composite Beam With I-Section, Jitesh Cherukkadu Parambil

Mechanical and Aerospace Engineering Theses - Archive

The advantage of material properties and flexibility of choosing material have made composite materials a primary preference for structural application. Unlike isotropic materials, the parametric study of composite beams for optimized design is complicated due to high number of parameters involved in designing like lay-up sequence, and layer configuration. Moreover, the limitations of FEA techniques in designing have created a need for an analytical closed-form solution for stress analysis of laminated composite beams. The objective of this study focuses on the development of an analytical method for stress analysis of composite I-beam. This method includes the structural response due to …


Solution To Multi Term Boltzmann Equation For Plasma Assisted Combustion, Antriksh Luthra Jan 2010

Solution To Multi Term Boltzmann Equation For Plasma Assisted Combustion, Antriksh Luthra

Mechanical and Aerospace Engineering Theses - Archive

Plasma assisted ignition and combustion (PAIC) is a technology where plasma is generated by high voltage, nano second pulse duration and high repetitive rate pulses. The high reduced electric field during the pulse allows efficient electronic excitation and molecular dissociation, thereby generating a pool of chemically active radical species. This speeds up the reaction process needed to generate a high speed flame a very high energy is liberated though the mode of excited electrons to the neutral molecules of the fuel in such a way that the energy sent should not go in momentum transfer but it should be so …


Kinematic Analysis Of A Quadruped Robot Capable Of Working As A Machining Tool, Raghu Mandayam Anand Jan 2010

Kinematic Analysis Of A Quadruped Robot Capable Of Working As A Machining Tool, Raghu Mandayam Anand

Mechanical and Aerospace Engineering Theses - Archive

Parallel robots have been proposed for some time now due to their potential advantages over serial robots in high load bearing, acceleration, stiffness and with lower moving mass. Mobile parallel configurations, i.e. multi-legged walking vehicles have been and are the focus of a great deal of current research. This thesis attempts to provide insights into the kinematic analysis of a quadruped robot capable of both walking and more importantly functioning as a machining tool. The gait analysis of quadruped robots has been extensively investigated and is not the focus of this research; however the gait ability is considered in the …


Effects Of Freezing On The Mechanical Properties Of Engineered Tissues, Lacey Mlcak Jan 2010

Effects Of Freezing On The Mechanical Properties Of Engineered Tissues, Lacey Mlcak

Mechanical and Aerospace Engineering Theses - Archive

Cryopreservation is used to preserve cells and tissues at low temperatures for short and long term uses. Some examples of where cryopreservation is used include the storage of organs, blood, embryos, and artificial tissues. A current challenge of cryopreservation is being able to understand and quantify the effects of freezing/thawing on the functional properties of tissues such as mechanical properties. This study investigated the changes in viscoelastic parameters of engineered tissues before and after freezing by performing creep-relaxation tests using a dynamic mechanical analyzer. Three types of engineered tissues were studied with varying cell and collagen concentrations for two different …


Experimental Study Of The Effects Of Thermally Conductive Microporous Coatings On Low Heat Flux Pool And Flow Boiling, Matthew Mlcak Jan 2010

Experimental Study Of The Effects Of Thermally Conductive Microporous Coatings On Low Heat Flux Pool And Flow Boiling, Matthew Mlcak

Mechanical and Aerospace Engineering Theses - Archive

This study examines the effect of the Thermally Conductive Micro-porous Coating (TCMC) developed at the University of Texas at Arlington, on an extended length heater in flow boiling. The study was performed with application to heat transfer in a tankless hot water heater in mind. The coating is composed of copper particles of micron size soldered to each other and to the substrate. The optimal TCMC (75µm particles with a thickness of 425µm±25µm) was first determined from pool boiling tests. The coating was then tested in flow boiling utilizing tap water as the working fluid at two different levels of …


Thermo-Mechanical Analysis Of A 3d Package In Microelectronics And Cooling Technologies For An Igbt Thermal Tester In Power Electronics, Abhilash Ramachandran Menon Jan 2010

Thermo-Mechanical Analysis Of A 3d Package In Microelectronics And Cooling Technologies For An Igbt Thermal Tester In Power Electronics, Abhilash Ramachandran Menon

Mechanical and Aerospace Engineering Theses - Archive

In the past, compact components such as chip scale packages and flip chip packages were the work horses of miniaturization. However emerging applications are now demanding even higher packaging density which has led to the evolution of 3D packaging, some of the advantages being minimal conductor length, reduce speed limiting inter chip interconnects. This has resulted in the emergence of 3D packaging technologies like stacked package, through silicon vias (TSV), package on package (PoP) etc. In order to address the various challenging requirements, PoP is seen as the leading 3D packaging platform by the system designers and semiconductor suppliers. PoP …


Buckling And Post Buckling Of Structural Components, Shruti Deshpande Jan 2010

Buckling And Post Buckling Of Structural Components, Shruti Deshpande

Mechanical and Aerospace Engineering Theses - Archive

Structural members and components, such as shells and trusses of different geometries, form the intricate and deep seated parts in the manufacturing of missiles submarines, rockets, airplanes, automobiles etc and find applications in civil structures such as bridges. These members are comprised of components like conical frusta, cylindrical panels and shallow trusses. In many cases, the sole purpose of such shell structures is to absorb the energy generated due to impact which means, that these structures are subjected to heavy loads and can experience failure due to buckling. The objective of this work is to study the buckling and post …


Aerodynamic Shape Optimization Of 3d Gas Turbine Blade Using Differerential Evolution Method, Darshak Joshi Jan 2010

Aerodynamic Shape Optimization Of 3d Gas Turbine Blade Using Differerential Evolution Method, Darshak Joshi

Mechanical and Aerospace Engineering Theses - Archive

This paper outlines the aerodynamics shape optimization process of a 3D VKI gas turbine blade using Computational Fluid Dynamics (CFD) and differential evolution optimization method. The main objective of this work is to improve outlet total pressure for better aerodynamic performance. This benefit is achieved by optimizing the stacking line path of the turbine blade in 3D annular cascade for which higher exit total pressure is achieved. The optimization process starts with generating a 3D annular cascade with a boundary domain and meshing it using GAMBIT and is then solved in FLUENT using viscous flow analysis. The original stacking line …


Simulation Of Indeterminate Multi-Point Impact And Contact With Friction, Adrian Rodriguez Jan 2010

Simulation Of Indeterminate Multi-Point Impact And Contact With Friction, Adrian Rodriguez

Mechanical and Aerospace Engineering Theses - Archive

This work presents a method for determining the post-impact behavior of a rigid-body undergoing simultaneous, multiple impacts with friction. A discrete algebraic model is used with an event-driven function which finds impact events. In this work, the indeterminate nature of the equations of motion encountered at impact are examined. A velocity constraint is developed based on the rigid-body assumption to address the equations and an impact law is used to determine the impulsive forces. The slip-state of each contact point is then determined and appropriate methods are used to resolve the post-impact velocities. Friction is treated as a complementarity problem …


Reanalysis For Static And Steady State Structure Response, Kunal Rohit Parikh Jan 2010

Reanalysis For Static And Steady State Structure Response, Kunal Rohit Parikh

Mechanical and Aerospace Engineering Theses - Archive

Reanalysis of a structure has become very important in structural analysis, as it reduces the cost and the computational time required to measure the response of the structure after it has been modified. As the importance of reanalysis has become clear, more and more research has been carried out in the field of reanalysis, which has lead to many different methods to carry out reanalysis. There are various methods which can be used for any single structural reanalysis problem and it would give us different results depending upon the method selected. Due to lot of methods which are available to …


Richtmyer-Meshkov Instability In Reactive Mixtures., Madhuri Ungarala Jan 2010

Richtmyer-Meshkov Instability In Reactive Mixtures., Madhuri Ungarala

Mechanical and Aerospace Engineering Theses - Archive

This research analyzes the effect of reactivity on the Richtmyer-Meshkov instability with particular emphasis on the velocity and wave number scaling and on the effect of free detonation instability modes on the interface corrugation rate. This analysis is performed by solving numerically for the first order perturbation generated by the shock-induced acceleration of an initially corrugated interface. The objective of this research is to analyze the effect of mixture reactivity on the process supported by a shock sweeping across a corrugated interface from high density to low density fluid. This scenario is antithetical to the classical Richtmyer analysis where transmitted …


Analysis Of Thrust Development In A Pulse Detonaton Engine, Kishore Nekkanti Jan 2010

Analysis Of Thrust Development In A Pulse Detonaton Engine, Kishore Nekkanti

Mechanical and Aerospace Engineering Theses - Archive

Pulse detonation engines (PDE) employ detonation waves to compress and burn the fuel and oxidizer mixture which results in the release of high pressure and temperature. The objective of the present study is to analytically model the PDE cycle and to study the pressure, temperature, velocity and density distributions during the Taylor rarefaction wave, reflected rarefaction wave and the blow down process. A two-dimensional supersonic nozzle is designed analytically by using the method of characteristics. The average values of nozzle thrust for one PDE cycle are calculated analytically using the impulse function and thrust coefficient. The variation of PDE thrust …


Multiscale Modeling Of Targeted Drug Delivery And Diep Flap Perfusion, Manohara Mariyappa Jan 2010

Multiscale Modeling Of Targeted Drug Delivery And Diep Flap Perfusion, Manohara Mariyappa

Mechanical and Aerospace Engineering Theses - Archive

Advances in computational techniques have changed diagnosis and treatment of chronic diseases. This thesis work is composed of developing computational models in two application areas: nanomedicine and determining DIEP flap perfusion for reconstructive surgery. Nanomedicine poses a new frontier in medical technology with the advantages of targeted delivery and patient specific medicine. Current advances in nanomedicine are aiding the discovery and rationale design of many new classes of nanoparticles as drug delivery vectors for cancer treatment and image enhancing. An important advantage of targeted drug delivery is reduced drug dosage that enables the minimization of adverse effects associated with elevated …


Thermal Management Of Outside Plant Telecommunication Cabinets: Design And Cfd Modeling Methodology, Feroz Ahamed Iqbal Mariam Jan 2010

Thermal Management Of Outside Plant Telecommunication Cabinets: Design And Cfd Modeling Methodology, Feroz Ahamed Iqbal Mariam

Mechanical and Aerospace Engineering Theses - Archive

Over the years there has been a steady increase in the number of transistors being packed into the same footprint of a die, which has led to an increase in the power densities of electronics. The thermal management of electronic equipment therefore is becoming an integral part of packaging design. Access networks provide the last mile of connectivity for the telecommunication network users. In the access network, the outside plant telecommunication cabinets houses electronic components and switching devices. These cabinets are standalone outdoor cabinets and many a times they are located in hostile environments. Therefore, it is necessary that these …


A Low Cost Micro Scale Cyclone Seperator- Design And Computational Fluid Dynamics Analysis, Deval Pandya Jan 2010

A Low Cost Micro Scale Cyclone Seperator- Design And Computational Fluid Dynamics Analysis, Deval Pandya

Mechanical and Aerospace Engineering Theses - Archive

Microparticle separation process has a variety of application varying from application in biological and biomedical industries for analysis and diagnosis, in biogas manufacturing to separate phases as well as in defense sector for detection of biological weapons like anthrax. Available electrical, magnetic, acoustic and various other methods are either very costly or not portable. The proposed design of micro scale cyclone separator is low cost as well as portable and easy to manufacture. Huge cyclone separators are widely used in various industries since decades but due to lack of research in micro scale cyclones no direct and sufficient data is …