Aerospace Engineering Commons^™

Ship Routing Determination By Virtual Measurements Of An Integrated System, Tsai-Hsin Chang, Jian-Qun Hou

Journal of Marine Science and Technology–Taiwan

According to the requirements of international maritime organization model course 7.03, electronic navigation systems are essential for project pilots. Global positioning system (GPS) is currently the most widely used electronic navigation equipment. However, because of the frequent blockages of GPS signals in complex environments, obtaining a precise and real-time position is difficult. To satisfy the requirement of effective and stable positioning of ship berthing and unberthing, another independent navigation system, inertial navigation system (INS), was adopted. In this study, we developed a 2-dimension (2D) GPS/INS-integrated system by using the constraint of a ship moving on a plane. If GPS signals …

Characterizing And Modeling The Progressive Damage Of Off-Axis Thermoplastic Plies: Effect Of Ply Confinement, Ditho Pulungan, Arief Yudhanto, Gilles Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although the mechanisms of degradation are, overall, quite similar between thermoset and thermoplastic composites, thermoplastic laminates exhibit a higher ductility. Because of that, classical models developed for thermosets fail in predicting accurately the response of thermoplastic-based laminates. Here, we demonstrate that simulations based on the properties identified on isolated thermoplastics unidirectional plies, as usually done for thermosets, result in large errors. This is explained by the significant load-bearing capacity of the ply in the transverse direction that remains even after the first-ply failure, as a result of the confinement provided by adjacent plies. This effect also exists in thermosets, but …

Design Of An Optimal Adaptive Intelligent Control Scheme For Statcom In A Series Compensated Wind Farm, Fei Wang, Kai-Hung Lu, Qiangqiang Xu, Ziwen Chen

Journal of Marine Science and Technology–Taiwan

This paper proposes a static synchronous compensator (STATCOM) for use with a self-excited induction generator (SEIG)-based wind farm. The STATCOM applies a damping controller based on an optimal adaptive intelligent controller (OAIC) comprising the critical network, the functional linkbased Elman neural network (FLENN), and the genetic algorithm hybrid time-varying particle swarm optimization (GAHTVPSO) algorithm. The OAIC improves the damping power oscillations in the SEIG-based series-compensated wind farm system. The node-connecting weights of the proposed FLENN and the critical network are trained online via a backpropagation (BP) algorithm, and the GAHTVPSO adjusts the learning rates of the BP algorithm to improve …

A Machine Learning Framework For Drop-In Volume Swell Characteristics Of Sustainable Aviation Fuel, Shane Kosir, Joshua Heyne, John Graham

Mechanical and Aerospace Engineering Faculty Publications

A machine learning framework has been developed to predict volume swell for 10 non-metallic materials submerged in neat compounds. The non-metallic materials included nitrile rubber, extracted nitrile rubber, fluorosilicone, low temp fluorocarbon, lightweight polysulfide, polythioether, epoxy (0.2 mm), epoxy (0.04 mm), nylon, and Kapton. Volume swell, a material compatibility concern, serves as a significant impediment for the minimization of the greenhouse gas emissions of aviation. Sustainable aviation fuels, the only near and mid-term solution to mitigating greenhouse gas emissions, are limited to low blend limits with conventional fuel due to material compatibility issues (i.e. O-ring swell). A neural network was …

Studies Of Two-Phase Flow With Soluble Surfactant, Ryan Peter Atwater

Dissertations

Numerical methods are developed for accurate solution of two-phase flow in the zero Reynolds number limit of Stokes flow, when surfactant is present on a drop interface and in its bulk phase interior. The methods are designed to achieve high accuracy when the bulk Péclet number is large, or equivalently when the bulk phase surfactant has small diffusivity

In the limit of infinite bulk Péclet number the advection-diffusion equation that governs evolution of surfactant concentration in the bulk is singularly perturbed, indicating a separation of spatial scales. A hybrid numerical method based on a leading order asymptotic reduction in this …

Examining ‘Inattentional Deafness’ In Error Hazard Assessment Of Cockpit Design In Utility Aircraft, Fiodesy Gemilang Putri

International Programs

To introduce the importance of inattentional deafness in minimizing the probability of failure, therefore, the safety level of utility aircraft could be enhanced.

Modeling And Simulation Of A Supercritical Co2-Liquid Sodium Compact Heat Exchanger For Sodium Fast Reactors, Hailei Wang, Sean M. Kissick

Mechanical and Aerospace Engineering Faculty Publications

The study focuses on modeling and simulations of sodium-sCO2 intermediary compact heat exchangers for sodium-cooled fast reactors (SFR). A simplified 1-D analytical model was developed in companion with a 3-D CFD model. Using classic heat transfer correlations for Nusselt number, some simulation results using the 1-D model have achieved reasonable match with the CFD simulation results for longer channels (i.e., 40 cm and 80 cm). However, for short channel (10 cm) when axial conduction within the sodium fluid is significant, the 1-D model significantly over-predicted the heat transfer effectiveness. By incorporating the temperature-jump model, the 1-D model can extend its …

Theoretical Modeling Of Heat And Mass Transfer Processes In Phase Change And Electrochemical Energy Storage Systems, Mohammad Parhizi

Mechanical and Aerospace Engineering Dissertations - Archive

Theoretical understanding of heat and mass transfer processes in energy storage and conversion devices is of much interest for a wide variety of engineering applications. Two commonly used mechanisms for energy storage are electrochemical energy storage, such as in Li-ion cells, and phase change based energy storage, such as in phase change materials (PCM). Previous studies show that heat and mass transfer in both PCMs and Li-ion cells are critical processes affecting the performance and safety of these systems. This dissertation investigates several theoretical aspects of heat and mass transfer in these energy storage systems, with the goal of improving …

Finite Element Based Methodology To Predict Fatigue Compression Failure In Composite Based On Fiber Kinking Damage Model, Md Saddam Hossain

Mechanical and Aerospace Engineering Dissertations - Archive

Advanced polymer matrix composites are widely used in designing high-performance and lightweight spacecraft, rotorcraft, and automotive structures, due to its superior performance such as specific stiffness, specific strength, and toughness, which are appealing in reducing the weight of these structures. One critical factor that limits the efficient design of structures composed of fiber-reinforced composites (FRP) is the vulnerability of the material under compression loading since compressive strength of FRP material is typically a lot less compared to the tensile strength. Moreover, composite structure may undergo compression loading either by accidentally or by deliberately, large margins of safety are usually imposed …

A Scaling Investigation Of Feasibility And Hover Endurance For Electric Quasi Quadrotor Configurations, Budhyant Venepalli

Mechanical and Aerospace Engineering Dissertations - Archive

Motivated by recent developments in distributed propulsion electric vehicles, an effort is made in the present study to numerically investigate the upper bound of hover endurance achievable by electric quasi-quadrotors at various mass scales in the range of 0.1 kg to 10000 kg total vehicle mass. A feasible rotor propulsion pod design space is determined considering physics-based conceptual design constraints defined by blade tip Mach number and Reynolds number to ensure effective and energy-efficient generation of lift. A conceptual level scaling optimization for two-bladed rotor quasi-quadrotors was carried out at constant blade tip speed. A momentum theory model, a blade …

A Molecular Scale Study Of Cavitation Growth And Shock Response In Soft Materials, Khandakar Mahmud

Mechanical and Aerospace Engineering Dissertations - Archive

Cavitation is a mechanism through which small vapor-filled cavities are formed in a liquid medium due to rapid changes of pressure. In liquid, the cavitation bubble is created when surrounding pressure drops below the saturation vapor pressure. Here, cavitation formation due to shock wave is considered. The molecular level heterogeneous and homogenous cavitation mechanisms and bubble growth kinetics in soft gelatin hydrogel and water has been studied. Gelatin, which is derived from collagen, is frequently used as a brain simulant material. As such, the morphology of gelatin is very different from water. In the heterogeneous cavitation study, using molecular dynamics …

Experimental And Numerical Study Of Open Bath Immersion Cooling Of Microprocessors., Amirreza Niazmand

Mechanical and Aerospace Engineering Dissertations - Archive

The increase on demand of communication and networking has resulted to increase for more powerful servers and bigger data centers. With increase the power of electronics, thermal management and cooling of the equipment become a gigantic challenge due to lower surface, they have higher power density and traditional methods of cooling become ineffective. Generally, air cooling method is the first option for cooling of the electronics due to cheaper price. To increase the efficiency and capacity of cooling liquid immersion cooling is used due to higher thermal properties like heat capacity and thermal conductivity compare to air. Two methods of …

Hypoid Gear Noise And Vibration Control In Automotive Rear Axle Systems, Chia-Ching Lin

Mechanical and Aerospace Engineering Dissertations - Archive

Gear whine is a key issue for the vehicle powertrain system, and the design of a quiet, reliable driveline system is highly desirable for the automotive industry. From past studies, the main source of excitation for gear vibration and noise is the transmission error (TE), which generates the dynamic mesh force between the gear teeth. Then the vibration transmits through the flexible axle components and radiates off from the surface of the axle housing structure. The dynamic responses of the hypoid geared rotor system in the rear axle have a significant effect on the performance of noise, vibration, and harshness …

A Multiscale Study Of Cavitation Mechanism And Damage In Soft Materials, Fuad Hasan

Mechanical and Aerospace Engineering Dissertations - Archive

Cavitation is defined as the formation and growth of the gaseous bubble in bulk liquid due to the tensile pressure followed by the violent collapse. The collapse of the bubble is particularly significant due to its potential to cause damage to relatively stronger materials by either creating pressure waves (symmetric collapse) or liquid jet (asymmetric collapse). The study of cavitation in soft materials (e.g., tissue, brain, gelatin gel, etc.) has, therefore, gained a fair share of attention in the scientific communities. Recent studies have indicated that cavitation could be one of the leading causes of the mild Traumatic Brain Injury …

Molecular Level Mechanical Properties Of Ultra High Temperature Ceramics And Their Nanocomposites, Md Riaz Kayser

Mechanical and Aerospace Engineering Dissertations - Archive

Ultra High-Temperature Ceramics (UHTC) have been of great interest in the spacecraft, aerospace, and aeronautic industry due to their high melting point and their potential application as a protective material for the stagnation areas of leading edges. In this work, the effect of nanoparticle reinforcement for achieving tailored mechanical properties of UHTC’s has been studied. Two different material systems have been considered, namely the ZrB2-based and the HfO2-based nanocomposites. In the first study, the grain boundary driven mechanical behavior of polycrystalline ZrB2 and ZrC-ZrB2 nanocomposites using large-scale molecular dynamics simulations have been performed. The atomistic models of polycrystalline ZrB2 and …

Reliability Enhancement Of Heterogeneous 3d Integrated Circuit And Characterization Of Thermal Interface Material, A S M Raufur Chowdhury

Mechanical and Aerospace Engineering Dissertations - Archive

Electronic products require high functional integration in small footprints with lower cost. At the same time, it is required to maintain effective communication between the IC’s and the electronic systems. Various challenges are arising due to these factors such as signal processing time, heat dissipation, structural integrity, chip package interaction which need to be dealt effectively during electronic packaging. 3D stacking of the processors and the components accomplishes these goals and in high computing application it reduces the delay. Through-silicon via (TSV) is the heart of 3D integration, and the stacking of chips is emerging now as a powerful tool …

Experimental Investigation Of Effect Of Support Structure Geometry On The Microstructure And Metallurgical Properties Of In718 Parts Fabricated By Selective Laser Melting, Sourabh Hemant Thakare

Mechanical and Aerospace Engineering Theses - Archive

Additive Manufacturing is a modern manufacturing technique that provides extreme design freedom and the ability to manufacture multiple parts with high complexities at the same time. Various fabrication techniques have been developed, and this study focuses on selective laser melting (SLM) due to its ability to provide near-perfect parts at low cost while being able to work with a wide range of materials. In SLM, the part is manufactured, layer-by-layer, by melting and solidification of powder material under controlled inert conditions. The fabrication of complex geometries is not possible without proper allocation of support structures for the part, which keeps …

Experimental Investigation Of Laser Scan Strategy On The Microstructure, Mechanical Properties And Residual Stress Of Inconel 718 Parts Fabricated By Selective Laser Melting, Kiriti Mamidi

Mechanical and Aerospace Engineering Theses - Archive

Inconel 718 (IN718) is a nickel-based superalloy which exhibits excellent tensile and impact resistant properties along with good corrosion resistance at high temperatures. However, due to the high toughness and work hardening, the machinability of this superalloy is low. Therefore, the selective laser melting (SLM) process has been adopted as an efficient technique to fabricate IN718 parts as it overcomes the problems associated with conventional manufacturing of superalloys. SLM is a widely used additive manufacturing technique which offers the possibility to induce multi-functionality into a single component, and thus reduce the number of components that are needed. In the SLM …

Numerical Analysis Of Immersion Cooling On A Server Using Al2o3/Mineral Oil Nanofluid, Prajwal Srinivas Murthy

Mechanical and Aerospace Engineering Theses - Archive

In the current world, technology has developed significantly, with a massive processing and storage of data, resulting in the high increase in Power Density and Heat Generation of servers, computers and its components in data centers. This calls for an engineering solution, for efficient heat dissipation of these servers to ensure their reliability and prolonged working. Air cooling is a prominent method of data center cooling. However, due to its low heat carrying capacity, it is not an efficient method for cooling high heat generating servers. There are two methods to remove this heat, increasing the area of heat transfer …

Optimum Design Of Shimmed Foil Bearing Considering Rotordynamic Stability, Venkata Sai Jyothish Atluri

Mechanical and Aerospace Engineering Theses - Archive

Air foil bearing technology has made substantial development in the past years and has found its applications in high speed turbomachinery. Yet the rotordynamic instability has still been a persisting issue in the single pad air foil bearings. The single pad bearing can resolve this issue by using large clearance with the shaft but the large clearance requires large impeller tip clearance which is not ideal. Multi pad air foil bearings with non-uniform clearance distribution can be used to improve the rotodynamic stability, but the three pad bearings have inferior load capacities due to the less angular length of each …