Engineering Commons^™

Automatic Carrier Landing System For V/Stol Aircraft Using L1 Adaptive And Optimal Control, Shashank Hariharapura Ramesh

Mechanical and Aerospace Engineering Theses - Archive

This thesis presents a framework for developing automatic carrier landing systems for aircraft with vertical or short take-off and landing capability using two different control strategies - gain-scheduled linear optimal control, and L1 adaptive control. The carrier landing sequence of V/STOL aircraft involves large variations in dynamic pressure and aerodynamic coefficients arising because of the transition from aerodynamic-supported to jet-borne flight, descent to the touchdown altitude, and turns performed to align with the runway. Consequently, the dynamics of the aircraft exhibit a highly non-linear dynamical behavior with variations in flight conditions prior to touchdown. Therefore, the implication is the need …

The Effect Of Temperature And Relative Humidity On The Corrosion Rates Of Copper And Silver In Electronic Equipment In The Presence Of Sulfur Environment, Kanan Pujara

Mechanical and Aerospace Engineering Theses - Archive

Data center consume a significant amount of energy for the continuous air-conditioning of the servers with high internal heat loads and to maintain the indoor temperatures within recommended operating levels as recommended by ASHRAE. As an alternate source to air-conditioning, air-side economizers are used to reduce power consumption. However, there is a reluctance in using this technique due to undetermined equipment reliability by introducing outside air pollutants which over time could cause failures. There is a need to know the degree of reliability degradation when the equipment is operated, outside the recommended range, in the allowable temperature-humidity range in geographies …

Additive Manufacturing And Stress Analysis Of Naturally And Artificially Optimized Celullar Structures, Sachin Jose

Mechanical and Aerospace Engineering Theses - Archive

The main objective of our research is to manufacture topology optimized cellular structures using 3D printing and polymer infusion and obtain their structural response. First, we have obtained topology optimized cellular structure of beam using an in-house topology optimization tool. The Solid Isotropic material with Penalization (SIMP) method of optimization is used for finding the optimal topology. Since we require a continuous structure where we can take advantage of additive manufacturing, a no-penalty approach was chosen. For 3D printing, first the optimized condition for manufacturing was determined. Important parameters on which manufacturing depend are Number of Shells, Infill percentage and …

Experimental Analysis Validating A Control Scheme To Develop A Dynamic Cooling Solution For Non-Uniform High Powered Electronic Devices In Data Center, Ruturaj Kiran Kokate

Mechanical and Aerospace Engineering Theses - Archive

The trend towards higher heat fluxes and non-uniform power distribution continues as we follow Moore’s law with technology nodes now approaching 10nm. Cooling is always designed for maximum junction temperature and as such it is important to mitigate hot spots. All cold plates have a static design by nature and do not possess the capability to respond to non-uniform heat dissipation. The unique “dynamic cold plate” concept aims to improving on conventional static designs through implementation of sensing and control, by redistributing the liquid across its body to counter varying power dissipation across the device being cooled.

Smart Bed And Contact Impact Of Flexible Bodies Using Energy Compensation Method, Pranav Parikh

Mechanical and Aerospace Engineering Theses - Archive

This work investigates robotic means to prevent pressure ulcers in human bodies. The smart bed is intended to act as an intelligent assistant to a care-giver that relieves some of the physical and mental burden involved in preventing pressure ulcers. This type of device is needed because of a labor shortage in the nursing field. The smart bed distinguishes itself from the current available measures by redistributing pressure and minimizing shear forces acting on the skin in contact. This is done by using data from the sensor grid installed on the bed surface and actuating the degrees of freedom associated …

Cfd Modeling And Parametric Study Of Vapor Chamber As Heat Spreaders For High-Power Electronic Devices, Dhanraj Arun Patil

Mechanical and Aerospace Engineering Theses - Archive

Technological developments have resulted in a growing demand for high power electronic devices. Although these high power devices meet the high performance requirements, they also generate a very large amount of heat which adversely affects their operating efficiency. Most part of the heat within a package is generated at the chip and hence it is imperative to keep junction temperature as low as possible. This is commonly achieved by using heat sinks mounted directly on top of the package. Heat sinks provide a significant enhancement in cooling by increasing the surface area. However, base thickness of heat sinks limits its …

The Effect Of Material Strain Hardening On The Buckling Strength Of A Perforated Plate Under Uniaxial Loading, Mayuri Suresh Patil

Mechanical and Aerospace Engineering Theses - Archive

Plates or members containing plate elements have been used in the offshore, aerospace and construction industry. Cutouts are often located to lighten the weight of the structure, but these cutouts reduce the ultimate strength of the plate. A number of studies have taken place for determining the buckling strength of a perforated plated but few discuss the effect of material strain hardening on the buckling strength of a perforated plate. Buckling strength is often considered as an important criterial to determine the serviceable limit of the perforated plate in the offshore structure. The aim of the present study is to …

Estimation Of Fracture Mechanics Parameters In 3d Tsv Package During Chip Attachment Process, Mohammed Shahid Ali

Mechanical and Aerospace Engineering Theses - Archive

Nowadays, the packaging of electronic products is becoming revolutionized, since the packages are becoming more and more complex, dense, thinner and lighter for greater portability. Miniaturization of packages is being taken to the next level, and hence, 3D packaging has become a hot topic in the present research area. Three dimensional chips stacking with TSV technology has gained momentum to meet such requirements of significant miniaturization and power reduction which result in increased performance. However, the unique issues related to yield and reliability of critical areas in TSV based 3D ICs need to be evaluated. Therefore, Reliability of such electronic …

Cfd Based Design And Modelling Of Wind Fence To Mitigate High-Speed Wind Loading On A Modular Data Center, Devi Prasad Gorrepati

Mechanical and Aerospace Engineering Theses - Archive

A Modular Data Center (MDC) is a portable method of deploying a data center’s capacity. As an alternative to the traditional data center, an MDC can be placed anywhere data capacity is required. But this comes at the cost of making the MDC operable at any desired location with the environmental factors such as earthquakes and heavy winds. This study focuses on mitigating high-speed wind loading on the MDCs by designing a wind fence to reduce wind speed. Although wind fences are used in many agricultural and farming practices, their usage pertaining to MDCs is very limited. The challenge is …

Enhancement Of Fog-Collection Efficiency Of A Raschel Mesh Using Surface Coatings And Geometric Changes, Mithun Rajaram

Mechanical and Aerospace Engineering Theses - Archive

In a few countries, such as Chile, a Raschel mesh is widely used in the field to collect fog. In this work, we explored the possibility of enhancing fog-collection efficiency of a typical Raschel mesh through surface modification and geometric changes. We demonstrated about 100% enhancement in the fog-collection efficiency.

Tbi Induced Rate Dependent Viscoelastic Response Of Axon: Predictions From A Mathematical Model, Manikanta Jonnalagadda

Mechanical and Aerospace Engineering Theses - Archive

Traumatic brain injury (TBI) accounts to almost one fifth of total fatal injuries. Even though there are various mechanisms hypothesized for the causes leading to TBI, diffuse axonal injury (DAI) is found to be the most observed criterion. The reason for axonal failure in DAI has been studied extensively using experimental and computational models. It was found that axons behave like viscoelastic materials, thus exhibiting rate dependent behavior under loading. This viscoelastic behavior of axons is believed to drive the failure of axons and its substructures. It was observed that axon failure is caused by failures and distortions in axonal …

The Relationship Of Life Prediction For Quad Flat N0-Lead Package (Qfn )Packages Using 4 Point Bend Test And Thermal Cycle Testing, Monisha Mohan

Mechanical and Aerospace Engineering Theses - Archive

In the structural design of the Printed Circuit Boards, the stiffness modulus of the involved Fr4 and Cu layers play an important role. The 4 point bend test is one of the few test methods which is included in the JEDEC standard for the Monotonic Bend characterization for board level interconnects. The study in the past has shown that the damage mechanism of these two testing methods is similar. And also, correlation had been drawn by observation of failure mechanism through Scanning Electron Microscope (SEM). The purpose of this study is to create a methodology for co-relating 4 point bend …

Parametric Study Of An Igbt Cold Plate And Affect Of Device Level Modelling On System Level Thermal Predictions, Abhishek Raj Urs Kadaba Nagaraja Urs

Mechanical and Aerospace Engineering Theses - Archive

In power electronics, as there is continuous increase in performance of the electronic devices, simultaneously the size of the components used in these devices keep on decreasing. This has resulted in increased power densities and the requirements for excellent cooling as well in order to avoid the failure of those devices. Traditionally, while designing a cooling system for a device, uniform heat flux is assumed throughout the components. In many cases this method may not be accurate for a particular model design. There are chances that the heat flux distribution around the components are non-uniform and requires a more accurate …

Additive Manufacturing Methodologies For Multi Process And Multi Material Scenarios, Tushar Saini

Mechanical and Aerospace Engineering Theses - Archive

Additive Manufacturing processes have been developing and continuously improving but are primarily constrained to single materials, albeit some commercial multi extrusion 3D printers do exist where by it is possible to print with multi-colored fluidic polymers or at most two filaments of the same type. 3D printing an object with volumetric varying properties requires manual modification of the G-Code, not a feasible option considering the average size of G-Code generated by the slicing software. This research focuses on developing a post processing methodology that modifies the large G-Code files generated by the slicing software according to user requirements. The proposed …

Board Level Flexural Reliability Testing And Failure Analysis Of Printed Circuit Boards With Wcsp Packages, Guruprasad Shrikant Shinde

Mechanical and Aerospace Engineering Theses - Archive

Printed circuit boards, widely known as PCBs; are the skeleton behind every technology today. Electronics have integrated with every other engineering domain to improve the outcomes. It is very important that they remain intact in slightly extreme physical conditions. They are used in wide range applications which may lead to mechanical stress-strain in some conditions. There are various boards with different kinds of packages on them. A 0.7mm thick board with WCSP; Wafer chip scale package is a prime specimen for my work. The research includes designing exact replica of given PCB into ANSYS and its reliability testing. A 3-point …

Evaluating And Augmenting Fuel-Saving Benefits Obtained In Aircraft Formation Flight, Wendy Awele Okolo

Mechanical and Aerospace Engineering Dissertations - Archive

When an aircraft flies, it generates wake vortices, which induce a non-uniform wind distribution in its wake. A trail aircraft, placed in the wake of a lead's aircraft vortices experiences this non-uniform wind distribution with varying directions and magnitudes, depending on the location within the wake. It has been demonstrated that there is a "sweet spot" within the wake of a leader in which a trail can experience upwash which leads to reduced drag. Through this mechanism, aircraft can save significant amounts of fuel by flying at the sweet spot of the lead aircraft's wake. This dissertation provides two metrics …

Bayesian Statistics And Information Fusion For Gps-Denied Navigation, Brian Lee Copp

Mechanical and Aerospace Engineering Dissertations - Archive

It is well known that satellite navigation systems are vulnerable to disruption due to jamming, spoofing, or obstruction of the signal. The desire for robust navigation of aircraft in GPS-denied environments has motivated the development of feature-aided navigation systems, in which measurements of \textit{environmental features} are used to complement the dead reckoning solution produced by an inertial navigation system. Examples of environmental features which can be exploited for navigation include star positions, terrain elevation, terrestrial wireless signals, and features extracted from photographic data. Feature-aided navigation represents a particularly challenging estimation problem because the measurements are often strongly nonlinear, and the …

Two Phase Flow Cfd Analysis Of Refrigerants In A Condenser Pipe For Prediction Of Pressure Drop And Pumping Power, Aniket Ramchandra Kalambe

Mechanical and Aerospace Engineering Theses - Archive

With the ever growing need of achieving optimum cooling at chip level at the expense of low input pumping power and keeping in check the Global Warming Potential (GWP) & Ozone Depletion Potential (ODP) has given rise to “two-phase on chip cooling” with nature friendly refrigerants. Currently, “air-cooling” and “single-phase water on-chip cooling” using copper micro-channel coolers are being used but “two-phase on chip cooling” with refrigerants have a very large scale & long lasting advantages over the prior. However, due to the perceived complexity of modelling two-phase flow, this solution is not yet well understood. Modelling of two phase …

An Invastigation Of Band-Limited Fluid Damper Configuration Using Lumped Parameter Modeling, Ye Hong

Mechanical and Aerospace Engineering Theses - Archive

Vehicle suspension system is one of the key factors related to the vehicle dynamic characteristic. The fine tuning of suspension system between vehicle handling and ride comfort is not only a trade-off between these two aspects, but also, has its impact on vehicle safety and durability. For an optimal damper performance, the damper needs to generate sufficient damping force at maneuvering frequency (< 2 Hz); and it also needs to generate less damping force, which allow spring to filter the high frequency noise (> 2 Hz) generated by vehicle travels along rough road condition at speed. In order to achieve such performance, a lumped parameter model of Band-Limited Damper is proposed. Frequency response of both Conventional Damper and Band-Limited Damper are …

Computational Analysis Of Enhancing Heat Transfer In A 3-D Stacked Die Using Different Finned Heat Sink, Deekshith Pittala

Mechanical and Aerospace Engineering Theses - Archive

3D die stacking is an exciting new technology that increases the transistor’s density by integrating two or more dies vertically with a dense high – speed interface. The result of 3D die stacking is a significant reduction of interconnect both within a die and across dies in a system. The objective of the thermal design requirement for a 3D stacked die package is to maintain the junction temperatures of the devices at or below specified limits. Installing the Heat sink aid the heat transfer activity from a package. The extent of cooling and the junction temperatures vary if the designs …

Developing And Validating Thermodynamic Models For Evaporative Cooling Employed In Data Centers, Niravkumar Prabhatsinh Dodia

Mechanical and Aerospace Engineering Theses - Archive

Cooling of Data centers is of paramount importance for continuous and reliable operation of Servers housed by them. Considerable amount of total power is used to drive the cooling activity. Various different types of cooling methods have been implemented and are currently operating in various data centers. Evaporative (Indirect/Direct) Cooling is trending these days because of its ability to provide cooling at minimal cost. Previous studies have presented various cooling plants in data centers and studied them. A dedicated model for Evaporative cooling is developed and validated. The data is computed assuming the developed cooling model operating at a particular …

Experimental Study On Effects Of Segregated Cooling Provisioning On Thermal Performance Of Information Technology Servers In Air Cooled Data Centers, Ashwin Venugopal Siddarth

Mechanical and Aerospace Engineering Theses - Archive

Modern Information Technology (IT) equipment are typically assumed to operate in quiescent airflow conditions in an uncontained data center facility. In this study, the multi-scaled thermal management strategies are reconsidered at the IT chassis and rack level for a containment system. For an ideal containment configuration of airflow provisioning the entirety of conditioned air provided by the Computer Room Air Conditioning (CRAC) unit would flow through the IT equipment and return back to the CRAC. But in actuality a lack of interfaced airflow distribution exists between the amount of conditioned air provisioned to the rack and the volume capacity ingested …

A Model Analysis Of Sand Insertion In Hydraulic Fractures, Ya Hao

Mechanical and Aerospace Engineering Theses - Archive

Hydraulic fracturing (fracking) is a well-stimulation technology to create large volume of fracture formation in rocks for gas and/or oil extraction. This technology has been applied to commercially exploit natural gas in unconventional shale reservoirs that contain immense quantity but low density of hydrocarbon sources. The productivity can be largely dependent on the connectivity of fractures that must stay open. However, upon initial hydraulic fracturing, the fractures would be closed due to high hydrostatic pressure deep inside the crust. Sand must be pumped into the fractures to keep them open. An in-depth understanding of the sand distribution and its dependence …

Magnetic Field Enhanced Thermal Conductivity Analysis Of Magnetic Nanofluids, Christopher Allen

Mechanical and Aerospace Engineering Theses - Archive

The magnetic properties of four water-based nanofluids consisting of Al2O3, CuO, Fe3O4, and SiO2 were exploited to analyze the effect of the application of an external magnetic field on the thermal conductivity of the nanofluid. When the magnetic field is applied, the magnetic dipole moments of the particles align and the particles come in contact with each other and form chains in the direction of the applied magnetic field. When parallel to the direction of heat flow, the magnetic field causes the effective thermal conductivity in the direction of the magnetic field to increase. A higher thermally conductive fluid can …

Design Of Elastic Metamaterials, Yu-Chi Su

Open Access Dissertations

This study focused on the design and fabrication of a double negativity and three broadband single negativity elastic metamaterials using a 3D printer. We investigated dispersion curves and dynamic material properties of the metamaterials. Negative phase velocity in the double negativity metamaterial was also demonstrated.

For metamaterials with single negativity, three types of broadband metamaterials were designed from parametric studies. A comparison showed that using frame bending/stretching mode is more effective than applying beam bending mode to broaden bandgap. Furthermore, it is found that adding internal resonant components could enlarge the bandgap. The single negativity metamaterials were validated by numerical …

Studying The Optimum Design Of Automotive Thermoelectric Air Conditioning, Alaa Attar

Dissertations

The remarkable amount of research being conducted on thermoelectrics gives the impression that this technology will have a bright future in power generation and temperature control systems. At the present time, thermoelectrics is applied widely for temperature control, but has not yet replaced conventional air-conditioning systems due to its lower performance. Currently, approximately 10% of annual vehicle fuel consumption corresponds to the air-conditioning system used to cool the vehicle cabin. Conventional air-conditioning systems cool the entire cabin; however, about 73% of a vehicle’s mileage occurs while the driver is the only occupant. These facts indicate the need for a single …

A Study On Evaporative Cooling For Data Centers & Artificial Neural Network Modeling, Pritam Karmokar

Mechanical and Aerospace Engineering Theses - Archive

This study mainly aims at exploring how, one of the best “Green” solutions for IT equipment cooling aka Evaporative Cooling, can be optimized for better future deployment. Also, this study focuses on ways to deploy Artificial Neural Network models to Dynamic Systems. Today, SERVERS are one of most important devices that our technology driven world cannot do without. Efficiently cooling these delicate yet highly power dense beasts, while being environment friendly is one of our prime concerns. This study is a combination of two deceptively divergent works. First, on exploring the workings of this technique by investigating one such Evaporative …

Cae Analysis On A Ford Ecoboost Mustang Connecting Rod For Forged Steel, Aluminum 7075, Shiva Prasad Keralapura Basavaraju

Mechanical and Aerospace Engineering Theses - Archive

Connecting rod is high volume production critical component in an automobile engine. Every Internal combustion engine uses a connecting rod. Connecting rod must have highest possible rigidity with lowest possible weight. The major stress developed in the connecting rod are axial stress, due to combustion chamber pressure, and bending stress, due to centrifugal effect. Connecting rod mainly fails due to fatigue; according to survey, about 90% of the time the failure is due to fatigue. CAE analysis on Ford Eco boost Mustang connecting rod is carried out to validate the life of the connecting rod for forged steel and Aluminium7075. …

Computational Model For Steady State Simulation Of A Plate-Fin Heat Exchanger, Ajit Rajesh Desai

Mechanical and Aerospace Engineering Theses - Archive

High performance heat transfer devices are critical components in hybrid power generation systems. The design of a Recuperator for 'waste heat recovery' is crucial for reducing the operating cost of a hybrid system. Plate-fin heat exchangers occupy a special position among high performance heat exchangers because of the compactness, efficiency and flexibility they offer. The performance of these heat exchange devices is typically very sensitive to fluid property variations, axial conduction and heat losses to environment. This thesis presents a numerical model of a plate fin heat exchanger in which fluid property variations including temperature driven changes in specific heat …

Numerical Simulation And Modeling Of Combustion In Scramjets, Ryan James Clark

Dissertations

In the last fifteen years the development of a viable scramjet has quickly approached the following long term goals: responsive sub-orbital space access; long-range, prompt global strike; and high-speed transportation. Nonetheless, there are significant challenges that need to be resolved. These challenges include high skin friction drag and high heat transfer rates, inherent to vehicles in sustained, hypersonic flight. Another challenge is sustaining combustion. Numerical simulation and modeling was performed to provide insight into reducing skin friction drag and sustaining combustion.

Numerical simulation was used to investigate boundary layer combustion, which has been shown to reduce skin friction drag. The …