Mechanical Engineering Commons^™

Design And Optimization Of Additively Manufactured Heat Sink And Heat Spreader For Microelectronics Cooling, Aditya Krishna Ganesh Ram

Mechanical and Aerospace Engineering Theses - Archive

High performance cooling is a critical requirement for modern microprocessors that generate large amounts of non-uniformly distributed heat. Metal heat spreaders and heat sinks have been traditionally used for thermal management. While the design of these components has traditionallly been restricted by manufacturability, in recent years, additive manufacturing has offered the capability to manufacture almost any design. This work analyzes and optimizes the performance of an additively manufactured heat sink and heat spreader. Computational heat transfer simulations were carried out to understand the variation of chip temperature and pressure drop for various designs. Discussion of key findings include the thermal …

Molecular Dynamics (Md) Thermal Simulations Of Molecular Bridging Across The Cathode-Separator Interface In Li-Ion Cell, Abhijeet Sundarrao Dhakane

Mechanical and Aerospace Engineering Theses - Archive

While Li-ion cells show outstanding electrochemical performance, their poor thermal transport characteristics results in reduced performance as well as significant safety concerns. The heterogeneous interface between cathode and separator plays a vital role in the dissipation of heat within a Li-ion cell. Previous studies showed that the cathode-separator interfacial thermal resistance contributes around 88% of total thermal resistance within the cell. In this research, thermal conductance across the cathode-separator interface is calculated using molecular dynamics simulations. Thermal transport in a pristine heterogeneous interface as well as interfaces functionalized with monolayers of APTES, nBTMS and MPTMS molecules is studied. The impact …

Comparative Rack Level Cfd Analysis Of Air To Hybrid Cooling Data Center, Jay Umeshkumar Parekh

Mechanical and Aerospace Engineering Theses - Archive

The demand of data storage in the world is increasing, with this increase, demand for large data centers is growing. In response, we need to look for energy-efficient solutions to reduce the energy consumptions of the data centers. We want to reduce the energy used for cooling while keeping the data center equipment temperature in allowable range in high power density data center. The liquid or hybrid cooled servers are the alternatives that may be used instead of traditional air-cooled servers at Rack Level for the cooling power - different inlet temperatures and different percentage of hybrid cooling. This will …

How Vision Governs The Collective Behaviour Of Dense Cycling Pelotons, J. Belden, Mohammad M. Mansoor, A. Hellum, S. R. Rahman, A. Meyer, C. Pease, J. Pacheco, S. Koziol, Tadd T. Truscott

Mechanical and Aerospace Engineering Faculty Publications

In densely packed groups demonstrating collective behaviour, such as bird flocks, fish schools or packs of bicycle racers (cycling pelotons), information propagates over a network, with individuals sensing and reacting to stimuli over relatively short space and time scales. What remains elusive is a robust, mechanistic understanding of how sensory system properties affect interactions, information propagation and emergent behaviour. Here, we show through direct observation how the spatio-temporal limits of the human visual sensory system govern local interactions and set the network structure in large, dense collections of cyclists. We found that cyclists align in patterns within a ± 30° …

Distributed State Estimation By Using Active-Passive Sensor Networks, Akhilesh Raj, S. Jagannathan, Tansel Yucelen

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel adaptive observer for heterogeneous sensor networks (HSNs) to estimate state vector of an unknown target or process by using the sensed output when the input to the target/process is also not known. In an HSN, nodes are considered either active or passive depending upon their ability to sense the target output. The local information exchange among the nodes is dictated by a connected graph. By using the criterion of collective observability, a novel distributed adaptive estimation is introduced where the nodes are allowed to have different sensor modalities. Stability analysis shows uniform ultimate boundedness of …

Investigation Of Fundamental Principles Of Rigid Body Impact Mechanics, Khalid Alluhydan

Mechanical Engineering Research Theses and Dissertations

In impact mechanics, the collision between two or more bodies is a common, yet a very challenging problem. Producing analytical solutions that can predict the post-collision motion of the colliding bodies require consistent modeling of the dynamics of the colliding bodies. This dissertation presents a new method for solving the two and multibody impact problems that can be used to predict the post-collision motion of the colliding bodies. Also, we solve the rigid body collision problem of planar kinematic chains with multiple contacts with external surfaces.

In the first part of this dissertation, we study planar collisions of Balls and …

Active-Passive Dynamic Consensus Filters For Linear Time-Invariant Multiagent Systems, J. Daniel Peterson, Tansel Yucelen, S. Jagannathan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Active-passive dynamic consensus filters consist of a group of agents, where a subset of these agents is able to observe a quantity of interest (i.e. active agents) and the rest are subject to no observations (i.e. passive agents). Specifically, the objective of these filters is that the states of all agents are required to converge to the weighted average of the set of observations sensed by the active agents. Existing active-passive dynamic consensus filters in the classical sense assume that all agents can be modeled as having single integrator dynamics, which may not always hold in practice. Motivating from this …

Stabilization Of Homoclinic Orbits Of Two Degree-Of-Freedom Underactuated Systems, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A hybrid controller for stabilization of homoclinic orbits of two degree-of-freedom (DOF) underactuated systems is proposed. The controller is comprised of continuous-time inputs, impulsive brakings, and virtual impulsive inputs for resetting of the passive coordinate. Impulsive brakings of the active coordinate result in instantaneous negative changes in the mechanical energy of the system. An impulsive dynamical system framework is adopted for modeling the hybrid dynamics and a Lyapunov function is defined for stabilization of the orbit. Sufficient conditions for stabilization are presented such that the Lyapunov function decreases monotonically under the action of the continuous inputs and undergoes negative jumps …

Reducing The Noise Impact Of Unmanned Aerial Vehicles By Flight Control System Augmentation, Matthew B. Galles

Mechanical & Aerospace Engineering Theses & Dissertations

The aim of this thesis is to explore methods to reduce the noise impact of unmanned aerial vehicles operating within acoustically sensitive environments by flight control system augmentation. Two methods are investigated and include: (i) reduction of sound generated by vehicle speed control while flying along a nominal path and (ii) reduction of acoustic exposure by vehicle path control while flying at a nominal speed. Both methods require incorporation of an acoustic model into the flight control system as an additional control objective and an acoustic metric to characterize primary noise sources dependent on vehicle state. An acoustic model was …

A Set-Theoretic Model Reference Adaptive Control Architecture With Dead-Zone Effect, Ehsan Arabi, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

By introducing a system error dependent learning rate, the recently proposed set-theoretic model reference adaptive control architecture provides user-defined worst-case performance guarantees on the system error between an uncertain dynamical system of interest and a given reference model. In this architecture, the adaptation process is always active. However, it is of practical interest to stop the adaptation process when it is not needed (i.e., in the presence of small system errors). Motivated from this standpoint, we present a new set-theoretic model reference adaptive control architecture with dead-zone effect. The key feature of our framework utilizes a modified and continuous generalized …

Event-Triggered Adaptive Distributed State Estimation By Using Active-Passive Sensor Networks, Akhilesh Raj, S. Jagannathan, Tansel Yucelen

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel event-triggered adaptive observer for each node in the heterogeneous sensor networks (HSNs) in order to estimate state vector of an unknown target or process by using the sensed output when the input to the target/ process is unknown. A subset of nodes in the HSN referred to as active nodes, can sense the target periodically, estimate the target state vector by using their adaptive observer and can communicate the estimated state vector of the target with the neighboring nodes including passive nodes only at event triggered instants. The adaptive observer parameters of active nodes are …

Turbine Passage Design Methodology To Minimize Entropy Production-A Two-Step Optimization Strategy, Paht Juangphanich, Cis De Maesschalck, Guillermo Paniagua

School of Aeronautics and Astronautics Faculty Publications

Rapid aerodynamic design and optimization is essential for the development of future turbomachinery. The objective of this work is to demonstrate a methodology from 1D mean-line-design to a full 3D aerodynamic optimization of the turbine stage using a parameterization strategy that requires few parameters. The methodology is tested by designing a highly loaded and efficient turbine for the Purdue Experimental Turbine Aerothermal Laboratory. This manuscript describes the entire design process including the 2D/3D parameterization strategy in detail. The objective of the design is to maximize the entropy definition of efficiency while simultaneously maximizing the stage loading. Optimal design trends are …

A Multi-Fidelity Prediction Of Aerodynamic And Sonic Boom Characteristics Of The Jaxa Wing Body, Forrest L. Carpenter, Paul G. A. Cizmas, Christian R. Bolander, Ted N. Giblette, Doug F. Hunsaker

Mechanical and Aerospace Engineering Student Publications and Presentations

This paper presents a detailed comparison between the linear panel solver PANAIR A502 and the in-house Navier–Stokes solver UNS3D for a supersonic low-boom geometry. The high-fidelity flow solver was used to predict both the inviscid and laminar flow about the aircraft geometry. The JAXA wing body was selected as the supersonic low-boom geometry for this study. A comparison of the undertrack near-field pressure signatures showed good agreement between the three levels of model fidelity along the first 0.8L of the signature. Large oscillations in the PANAIR results were observed. The PANAIR discrepancies were traced back to violations of the …

Estimation Of The Region Of Attraction Of Underactuated Systems And Its Enlargement Using Impulsive Inputs, Nilay Kant, Ranjan Mukherjee, Dhrubajit Chowdhury, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Stabilization of an equilibrium point is an important control problem for underactuated systems. For a given control design, the ability of the system to remain stable in the presence of disturbances depends on the size of the region of attraction of the stabilized equilibrium. The sum of squares and trajectory reversing methods are combined together to generate a large estimate of the region of attraction. Then, this estimate is effectively enlarged by applying the impulse manifold method, which can stabilize equilibria from points lying outside the estimated region of attraction. In this paper, the generality of the approach is demonstrated …

Nanoparticle Injector For Photonic Manipulators Using Dielectrophoresis, Jaykob Maser, Joshua Rovey

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We describe the concept of a dielectrophoretic nanoparticle injector and its use in a plasmonic/photonic-based nanoparticle manipulation system. Particle motion is achieved by generating an electrostatic, non-uniform field between two tilted plates and applying the corresponding dielectrophoretic force to net-neutral nanoparticles. We investigate the dependence the dielectrophoretic force has on the plate angle of the charged plates as well as their separation distance, dielectric filler material, and exit interface membrane. Our results indicate an increasing average and maximum dielectrophoretic force attainable in the axial direction with corresponding decreasing plate angle and gap distance. The model also predicts larger field variation …

Modifying Casting Parameters To Improve The High Temperature Ductility Of Investment Cast Nickel-Based Superalloy Pwa 1455, Lars Alexander Hedin, Cole Magnum Introligator

Materials Engineering

PCC Structurals, an industry leader in superalloy investment castings, has observed inconsistencies in the stress rupture performance of polycrystalline nickel-based superalloy PWA 1455. PCC has changed their casting parameters to reduce the thermal gradient during cooling but have been unable to correlate these changes with an increase in stress rupture elongation. Metallographic examination of past samples indicated microstructures composed of non- equiaxed dendritic grains with mean diameter of .021 inches along the test axis. A similar study on polycrystalline superalloys has indicated that excessive superheat temperatures above the liquidus can result in large grains identical to those observed, limiting the …

Redesign Of Cubesat For Beam Charging, Kuba Preis

Industrial and Manufacturing Engineering

This paper is intended to be a study in the applications of the design freedom granted by additive manufacture in the design of a 1U CubeSat frame. The main loads experienced by a CubeSat are structural (during launch) and thermal (solar radiation). Beam charging is an emerging technology which involves charging a CubeSat using a laser beam. In this paper, a CubeSat frame was redesigned to account for the structural loads induced during launch and the thermal loads induced when beam charging. The thermal, weight, design, and structural requirements for a new CubeSat design were derived. The 1U CubeSat frame …

Computation Of Flow Fields Due To Single- And Twin-Jet Impingement, Xiang Zhang

McKelvey School of Engineering Graduate Student Theses & Dissertations

The thesis consists of two parts. The first part focuses on numerical simulations and their comparison with experimental data for single-jet impingement on ground. Angles between the axisymmetric jet and impingement surface considered are 15, 30 and 90 degree. It is shown that both the k-epsilon and Wray-Agarwal (WA) model can predict the flow fields in good agreement with the experimental results. The second part extends the first part to twin-jet normal impingement on the ground. It focuses on numerical simulation of fountains formed by the twin-jet impingement. The fountains can be normal straight upward when the two jets are …

Subscale Mars Colonization Mission, Cameron J. Lamack, James Lumsden, Sean Nevin, Donner Schoeffler, Riley Evers, Alexandra Poulakos, Skyler Tan, Anthony Keba, Siraj Zaman, Ali Altamimi, Anthony Modica

Honors Thesis

The team will compete in the SAE (Society of Automotive Engineers) Aero Design West Advanced Class competition, held 5-7th April 2019 in Van Nuys, California. The team will work to develop, through research, design, optimizational trade studies, and manufacturing, a system for the deployment of parasitic aircraft, as well as payload. The system will consist of a primary fixed-wing aircraft, parasitic autonomous gliders, a real-time altitude data acquisition system, as well as both static and releasable payload. The deployable gliders must navigate autonomously to a targeting area on the ground without any on-board propulsion. The releasable payload, which will consist …

Production Of Liquid Fuels From Natural Gas: Simulation Of Synthesis Gas And Fischer-Tropsch Reactors, Saiedeh Arabi Bolaghi

Mechanical and Aerospace Engineering Dissertations - Archive

Gas to Liquid (GTL) processes chemically convert natural gas to valuable liquid hydrocarbon products. The GTL process considered in this research is comprised of three phases: 1) syngas production, 2) Fischer-Tropsch synthesis (FTS), and 3) product separation. This study focuses on the simulation and optimization of a GTL process to convert natural gas to more valuable liquid fuels. In syngas production, steam methane reforming (SMR) is typically used although it requires an external heat source due to the endothermic nature of the reaction. In addition, the SMR approach produces syngas with a hydrogen to carbon monoxide ratio that is not …

Gasdynamic Phenomena And Propulsive Performance Of Pulse Detonation Engines, James T. Pearce

Mechanical and Aerospace Engineering Dissertations - Archive

The pulsed detonation engine (PDE) is an advanced propulsion system that makes use of intermittent detonations to provide thrust. In recent decades, the PDE has been at the center of various propulsion research efforts focused on practical implementation of a reliable detonation-based engine for aerospace propulsion applications. However, many design challenges remain to be solved due to the PDEs unsteady operating characteristics. In particular, the unsteady nature of the thrust chamber flow field inherent to the PDE operation makes the design of nozzles aimed at adequately expanding the burned detonation products especially difficult. In order to address this design challenge, …

Onboard Payload Mass Estimation And Electric Propulsion Modeling For Multicopters With Application In Unmanned Aerial Systems, Abel Martinez Martinez Martinez

Mechanical and Aerospace Engineering Theses - Archive

Unmanned vehicles are the future. The aim of the future online retailers, delivery and transportation companies would be air delivery using unmanned aerial vehicles. Multicopters are becoming rapidly famous because they o er a relatively easy-to-fly platform that is also very stable, and their mechanical simplicity. The possibility of estimating the weight of the multicopter in real time is really useful. A weight estimation system that could be implemented in multicopters with cable suspended payloads without using any extra sensors is presented in this thesis. The weight estimation system uses a functional relationship that correlates Pulse Position Modulation (PPM) signal …

Experimental Analysis For Optimization Of Thermal Performance Of A Server In Single Phase Immersion Cooling, Pravin Ashok Shinde

Mechanical and Aerospace Engineering Theses - Archive

Liquid immersion cooling of servers in synthetic dielectric fluids is an emerging technology which offers significant cooling energy saving and increased power densities for data centers. A noteworthy advantage of using immersion cooling is high heat dissipation capacity which is roughly 1200 times greater than air. Other advantages of dielectric fluid immersion cooling include high rack density, better server performance, even temperature profile, reduction in noise. The enhanced thermal properties of oil lead to the considerable saving of both upfront and operating cost over traditional methods. In this study, a server is completely submerged in a synthetic dielectric fluid. Experiments …

Onboard Payload Mass Estimation And Electric Propulsion Modeling For Multicopters With Application In Unmanned Aerial Systems, Abel Martinez Martinez

Mechanical and Aerospace Engineering Theses - Archive

Unmanned vehicles are the future. The aim of the future online retailers, delivery and transportation companies would be air delivery using unmanned aerial vehicles. Multicopters are becoming rapidly famous because they o er a relatively easy-to-fly platform that is also very stable, and their mechanical simplicity. The possibility of estimating the weight of the multicopter in real time is really useful. A weight estimation system that could be implemented in multicopters with cable suspended payloads without using any extra sensors is presented in this thesis. The weight estimation system uses a functional relationship that correlates Pulse Position Modulation (PPM) signal …

Computational Analysis For Thermal Optimization Of Server For Single - Phase Immersion Cooling, Dhruvkumar Vimalkumar Gandhi

Mechanical and Aerospace Engineering Theses - Archive

Complete immersion of servers in synthetic dielectric fluids is rapidly becoming a popular technique to minimize the energy consumed by data centers for cooling purposes. In general, immersion cooling offers noteworthy advantages over conventional air-cooling methods as synthetic dielectric fluids have high heat dissipation capacities which are roughly about 1200 times greater than air. Other advantages of dielectric fluid immersion cooling include even temperature profile on chips, reduction in noise and addressing reliability and operational enhancements like whisker formation and electro-chemical migration. Nevertheless, lack of data published and availability of long-term reliability data on immersion cooling is insufficient which makes …

Electroextraction Across Droplet-Droplet Interface, Subhadeep Chakraborti

Mechanical and Aerospace Engineering Theses - Archive

Extraction of analytes from solvents is a crucial part of many medical, clinical, industrial and refinery processes. It is required for preconcentration of analytes into other solvents, purification of solvents and detection of harmful or toxic molecules. One of the very important methods of extraction in microfluidics is liquid-liquid extraction (LLE). LLE involves the use of two immiscible liquids for diffusion of analytes across the interface. Recently there has been a growing interest in the coupling of external electric field with LLE to enhance the extraction of charged analytes. This has led to the birth of a new extraction method …

Effect Of Dielectric Inter-Layer In Performance Of The Multi-Functional Material In Mechanical, Thermal And Environmental Loading Conditions, Rauhon Ahmed Shaik

Mechanical and Aerospace Engineering Theses - Archive

The demand for Electrical power storage devices for space shuttle, aircraft, car, bus and marine vehicles increased a great deal to have a greener and safer world. Decades of research has been done on development of light weight and high-performance energy storage devices such as batteries and structural capacitors. The use of structural capacitors can solve the high-performance energy storage requirement with no dead weight and also gives a strong structure. However, these heterogeneous materials experience different thermal expansions across the dielectric and electrodes inter layers due to which the energy storage capacity and mechanical performance evolve over time. Hence, …

Methodology To Develop Artificial Neural Network Based Control Strategies For Multiple Air-Cooling Units In A Raised Floor Data Center, Vibin Shalom Simon

Mechanical and Aerospace Engineering Theses - Archive

A data center consists of a hierarchy of systems with dedicated control algorithms dictating their operational states. We could say, there exists an ensemble of dynamical systems, each executing a control task, while the global objective is to drive the overall system to an optimum i.e. minimum total operational power at desired rack inlet temperatures. The dynamics of the Information Technology Equipment (ITE) workload and the cooling provisioning is non-linear in spatial and temporal parameter space. Data-driven modelling is one method to realistically model such non-linear dynamics and make predictions that are necessary for improved control design of the cooling …

Numerical And Experimental Study On Turbulence Production Of A Selected Mode Of Streamwise Vortex Interaction In Supersonic Flow, Davide Viganó

Mechanical and Aerospace Engineering Dissertations - Archive

The development of effective mixing strategies of air/fuel mixtures in supersonic flows has been the subject of a significant body of research for the last 60 years due to the hindering effects of compressibility. Particular attention has been focused on the introduction of streamwise vortices as a way to enhance molecular mixing both in terms of added source for hydrodynamic instabilities on classical shear-layer flows as well as for transverse jet configurations, aero-ramps and hypermixers. However, a large portion of fundamental knowledge for these complex flows is still missing. This work is centered on a numerical and experimental study of …

Characterization Of 3d Printed Pla With The Help Of Mechanical, Di-Electric And X-Ray Diffraction Techniques, Sai Sri Nidhi Munaganuru

Mechanical and Aerospace Engineering Theses - Archive

Additive manufacturing (AM) revolutionized many industries, i.e., Automotive, Biomedical, Aerospace and Defense. As opposed to traditional manufacturing methods, a part is manufactured layer by layer from 3D CAD models in AM. Though the vision of AM is impressive, there are many challenges that are hindering the widespread use of these complex parts. One of the main challenges is its strength that varies with different manufacturing parameters. We are going to investigate the effect of build parameters on the mechanical, electrical and crystalline properties of the additively manufactured heterogeneous material system. The goal of the thesis is to find a correlation …