Aerospace Engineering Commons^™

Effects Of Machining Parameters And Cooling Strategies On Cutting Forces And Surface Integrity In High-Speed Slot End-Milling Of Titanium Alloy, Emenike Chukwuma

Masters Theses

“Paper 1 presents the results of the investigations of the effects of cooling strategies [Emulsion cooling, Minimum Quantity Lubrication (MQL) and Liquid Nitrogen (LN₂)] and machining parameters (feed rate and spindle speed) on cutting force components, cutting temperature and tool wear during slot end-milling of titanium Ti-6Al-4V workpiece. All machining experiments were conducted using four-flute 0.5 inch diameter uncoated solid carbide end-mill on Cincinnati Milacron, Sabre 750 vertical machining center equipped with Acramatic 2100 controller. Cutting force components were acquired and tool wear was indirectly measured from maximum cutting force variation per slot from the first pass to …

Proceedings Of The First International Conference On Smarandache Multispace & Multistructures, Florentin Smarandache, Linfan Mao

Branch Mathematics and Statistics Faculty and Staff Publications

In recent decades, Smarandache’s notions of multispace and multistructure were widely spread and have shown much importance in sciences around the world. Organizedby Prof.Linfan Mao, a professional conference on multispaces and multistructures, named the First International Conference on Smarandache Multispace and Multistructure was held in Beijing University of Civil Engineering and Architecture of P. R. China on June 28-30, 2013, which was announced by American Mathematical Society in advance.

Bio-Inspired Cooperative Optimal Trajectory Planning For Autonomous Vehicles, Charles Remeikas

Electronic Theses and Dissertations

With the recent trend for systems to be more and more autonomous, there is a growing need for cooperative trajectory planning. Applications that can be considered as cooperative systems such as surveying, formation flight, and traffic control need a method that can rapidly produce trajectories while considering all of the constraints on the system. Currently most of the existing methods to handle cooperative control are based around either simple dynamics and/or on the assumption that all vehicles have homogeneous properties. In reality, typical autonomous systems will have heterogeneous, nonlinear dynamics while also being subject to extreme constraints on certain state …

Chemoelastoplastic Analysis Of A Copper-Graded Silicon Nanorod For Lithium-Ion Battery Anode Application, Chao Ji

Mechanical and Aerospace Engineering Theses - Archive

Lithium-ion batteries are currently widely used in electronics, electrical vehicles and other devices/machines. Along with the mounting demand for much improved performance in these developing technological fields, silicon was recognized to possess much higher energy capacity when used as an anode than graphite that is currently used. However, there occurs colossal volume expansion of silicon anode during the lithiation process. The material consequently suffers enormous stresses, especially, at the interface with a current collector, which deteriorate the device quickly during cycling. To prevent the active material (Si) from falling off from a current collector, nanoengineering strategies have been suggested, including …

Application Of Phase Change Material In Sustainable Cooling Of Data Centers, Nikhil Dhiman

Mechanical and Aerospace Engineering Theses - Archive

The ever increasing information technology heat load and data center cooling energy are the main reasons to investigate the performance of microencapsulated phase change slurry over other heat transfer fluids. In recent years, more effort is being made on the development of a new technique to use the phase change materials as pump-able heat transfer fluid and as heat storage system.Microencapsulated phase change slurry is dispersion where the phase change material, microencapsulated by a polymeric capsule, is dispersed in water. Compared to water, these new fluids have a higher heat capacity during phase change and a possible enhancement, as a …

Thermal Management Method For Foil Bearings In Turbine Hot Section, Tejas Devidas Patil

Mechanical and Aerospace Engineering Theses - Archive

Recently, Air Foil Bearings (AFB) are gaining higher industrial acceptance in micro-turbo machinery. AFB show high speed operating capability and environmental friendly operation in comparison to rolling element bearings. Utilization of ambient air as a lubricant eliminates maintenance of a pressurized oil lubricating system. AFBs are therefore a feasible alternative to oil lubricated bearings in small machines. High speed operation results in thermal management issues which can be solved through a suitable cooling mechanism. Axial cooling by passing air through bearing support structure (called bump foils) is the most commonly used. In this method, cooling is achieved in the heat …

Immersion Cooling Of High End Data Center Server And Validation Through Experiments, Harsh Patel

Mechanical and Aerospace Engineering Theses - Archive

Despite recent improvements in data center cooling efficiency such as hot and cold aisle and air side economizer, air cooling may not have the capacity to cool high end racks such as from IBM's NetBAY42 (150Kw and above). Increasing computer capabilities in data center has resulted in increase in rack power density per square ft as indicated by the latest uptime. The cooling of such high powered servers and corresponding racks poses a significant challenge to thermal engineers.The use of immersion cooling is novel approach for data center cooling. In this study after some modification high powered server is fully …

Vision-Based Sensing And Optimal Control For Low-Cost And Small Satellite Platforms, Bradley Sease

Electronic Theses and Dissertations

Current trends in spacecraft are leading to smaller, more inexpensive options whenever possible. This shift has been primarily pursued for the opportunity to open a new frontier for technologies with a small financial obligation. Limited power, processing, pointing, and communication capabilities are all common issues which must be considered when miniaturizing systems and implementing low-cost components. This thesis addresses some of these concerns by applying two methods, in attitude estimation and control. Additionally, these methods are not restricted to only small, inexpensive satellites, but offer a benefit to large-scale spacecraft as well. First, star cameras are examined for the tendency …

Mission Analysis For Pico-Scale Satellite Based Dust Detection In Low Earth Orbits, Jacob Belli

Electronic Theses and Dissertations

A conceptual dust detection mission, KnightSat III, using pico-scale satellites is analyzed. The purpose of the proposed KnightSat III mission is to aid in the determination of the size, mass, distribution, and number of dust particles in low earth orbits through a low cost and flexible satellite or a formation of satellites equipped with a new dust detector. The analysis of a single satellite mission with an on-board dust detector is described; though this analysis can easily be extended to a formation of pico-scale satellites. Many design aspects of the mission are discussed, including orbit analysis, power management, attitude determination …

A Numerical Study Of Incompressible Fluid Flow Over A Forward Facing Step At Various Grades, Peter Andrew Martinez

Mechanical and Aerospace Engineering Theses - Archive

The study of the effect of natural forces on hydraulic structures is of great concern for the accurate prediction of when a design could be at risk of failure. In recent times the use of the shallow water equations to predict the behavior of the free surface for flow over a step has proven inaccurate because only a hydrostatic pressure distribution is considered. One of the phenomena that will not be accounted for with the shallow water equations in such a setup is the formulation of undular bore type waves on the surface. In order for a more accurate representation …

Design, Fabrication And Test Of Surface Tension-Driven Microboats And Thermally Oscillatory Bubble-Propelled Microsubmarines, Lei Qiao

Mechanical and Aerospace Engineering Dissertations - Archive

In this work, we develop microboats and microsubmarines, which are capable of moving on and under water, respectively. The microboat is propelled due to the difference between surface tensions around stern and bow. This difference is generated by releasing a liquid with lower surface tension than water from the stern. We explore both horizontal and vertical motions of the microboats through a combination of experimental and theoretical investigations. It has a length of 8 mm and weight of 20 mg with the highest speed of 25 cm/s and travel distance of 85 cm. Moreover, we design, fabricate and test microboats …

Experimental Characterization Of Roughness And Flow Injection Effects In A High Reynolds Number Turbulent Channel, Mark A. Miller

Theses and Dissertations--Mechanical and Aerospace Engineering

A turbulent channel flow was used to study the scaling of the combined effects of roughness and flow injection on the mean flow and turbulence statistics of turbulent plane Poiseuille flow. It was found that the additional momentum injected through the rough surface acted primarily to enhance the roughness effects and, with respect to the mean flow, blowing produced similar mean flow effects as increasing the roughness height. This was not found to hold for the turbulence statistics, as a departure from Townsend’s hypothesis was seen. Instead, the resulting outer-scaled streamwise Reynolds stress for cases with roughness and blowing deviated …

Near Wall Shear Stress Modification Using An Active Piezoelectric Nanowire Surface, Christopher R. Guskey

Theses and Dissertations--Mechanical and Aerospace Engineering

An experimental study was conducted to explore the possible application of dynamically actuated nanowires to effectively disturb the wall layer in fully developed, turbulent channel flow. Actuated nanowires have the potential to be used for the mixing and filtering of chemicals, enhancing convective heat transfer and reducing drag. The first experimental evidence is presented suggesting it is possible to manipulate and subsequently control turbulent flow structures with active nanowires. An array of rigid, ultra-long (40 μm) TiO₂ nanowires was fabricated and installed in the bounding wall of turbulent channel flow then oscillated using an attached piezoelectric actuator. Flow velocity …

Numerical Modeling And Characterization Of Vertically Aligned Carbon Nanotube Arrays, Johnson Joseph

Theses and Dissertations--Mechanical and Aerospace Engineering

Since their discoveries, carbon nanotubes have been widely studied, but mostly in the forms of 1D individual carbon nanotube (CNT). From practical application point of view, it is highly desirable to produce carbon nanotubes in large scales. This has resulted in a new class of carbon nanotube material, called the vertically aligned carbon nanotube arrays (VA-CNTs). To date, our ability to design and model this complex material is still limited. The classical molecular mechanics methods used to model individual CNTs are not applicable to the modeling of VA-CNT structures due to the significant computational efforts required. This research is to …

Numerical Study Of Pressure Fluctuations Due To A Mach 6 Turbulent Boundary Layer, Lian Duan, Meelan M. Choudhari

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Reτ ≈ 464. The emphasis is on comparing the primarily vortical pressure signal at the wall with the acoustic freestream signal under higher Mach number conditions. Moreover, the Mach-number dependence of pressure signals is demonstrated by comparing the current results with those of a supersonic boundary layer at Mach 2.5 and Reτ ≈ 510. It is found that the freestream pressure intensity exhibits a strong Mach number dependence, irrespective of …

Robustness Of A Derivative-Free Adaptive Control Law In The Presence Of Unmodeled Dynamics, Tansel Yucelen, Anthony J. Calise

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although adaptive control theory offers mathematical tools to achieve required system performance without excessive dependence on modeling, its application to safety-critical systems can be limited by the presence of unmodeled dynamics. This paper examines the robustness to unmodeled dynamics of a recently developed derivative-free adaptive control law. In contrast to derivative-based adaptive laws it is shown, using a Lyapunov-Krasovskii functional, that robustness to unmodeled dynamics is improved by increasing the adaptation gain. This is accomplished by including a bias term in the set of basic functions employed by the adaptive control law. It is shown that derivative-based adaptive laws do …

Neuropredictive Control And Trajectory Generation For Slung Load Systems, Gerardo De La Torre, Eric N. Johnson, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a neuropredictive trajectory generation architecture for slung load systems. The presented architecture integrates the real-time trajectory generation method with a system uncertainty identifying neural network. It is shown that the effect of system uncertainty on a model predictive control approach can be mitigated by the use of neural networks. A numerical example of an uncertain slung load system is shown to demonstrate the effectiveness of the presented framework.

Consensus Protocols For Networked Multiagent Systems With Relative Position And Neighboring Velocity Information, Gerardo De La Torre, Tansel Yucelen, Eric N. Johnson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The consensus problem appears frequently in the coordination of multiagent systems in science and engineering and involves the agreement of networked agents upon certain quantities of interest. In this paper, we focus on a new consensus protocol for networked multiagent systems. The proposed control protocol consists of a standard term capturing relative position information and a new term capturing neighboring velocity information. In particular, the addition of the latter term results in an increase of the rate of system convergence while maintaining a fixed graph structure and without increasing the maximum eigenvalue of the graph Laplacian. Furthermore, in certain cases, …

Separate-Channel Integrated Guidance And Autopilot For Automatic Path-Following, Takeshi Yamasaki, S. N. Balakrishnan, Hiroyuki Takano

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An integrated guidance and autopilot scheme for a path-following uninhabited aerial vehicle is presented in this study. A fixed-wing aircraft usually performs a bank-to-turn maneuver to change its flight direction. The novel approach presented here, however, assumes that each of the three channels of the integrated guidance and autopilot can be independently designed. This concept makes the design process simple. A virtual target moving on the prespecified path for the uninhabited aerial vehicle is introduced to facilitate the algorithm development. A first-/ second order sliding structure with a second order sliding mode and a high-order sliding mode differentiator for the …

Dynamic Mechanical Analysis And Computer Simulation Of Polyurea Aerogels, Victoria Ann Prokopf

Masters Theses

"Historically, the use of aerogels has been limited due to their poor mechanical properties. However, polyurea aerogels have proven to be mechanically strong under quasi-static conditions. Polyurea aerogels can be created by filling molds of the desired shape with a liquid solution that then creates a solid gel filled with liquid. The liquid can be removed from the gel by supercritical drying. This thesis outlines dynamic testing as well as simulation for polyurea aerogels.

Testing has been conducted in dynamic tension and bending for densities of polyurea aerogels ranging from 0.12 g/cm³ to 0.31 g/cm³. In most …

Wind Loading On Trees Integrated With A Building Envelope, Aly Mousaad Aly, Alberto Zasso, Girma Bitsuamlak, Alberto Nicola Longarini, Arindam Gam Chowdhury

Faculty Publications

With the sustainability movement, vegetated building envelopes are gaining more popularity. This requires special wind effect investigations, both from sustainability and resiliency perspectives. The current paper focuses on wind load estimation on small- and full-scale trees used as part of green roofs and balconies. Small-scale wind load assessment was carried out using wind tunnel testing in a global-effect study to understand the interference effects from surrounding structures. Full-scale trees were investigated at a large open-jet facility in a local-effect study to investigate the wind-tree interaction. The effect of Reynolds number combined with shape change on the overall loads measured at …

The Potential Costs To The Dod Of Not Preparing For The Nextgen Nas Overhaul: Lessons Learned From Rvsm, Casey Richardson

Graduate Student Works

In order to facilitate a significant overhaul of the civilian National Airspace System (NAS), the Federal Aviation Administration (FAA) has partnered with many federal agencies, such as the departments of Transportation (DOT), Defense (DoD), Homeland Security (DHS), and Commerce (DOC) and the National Aeronautics & Space Administration (NASA) through a consolidated Joint Planning and Development Office (JPDO) that was established by Congress in 2003 in the VISION 100 – Century of Aviation Reauthorization Act (JPDO, 2012). The JPDO has proposed replacing the old NAS structure of primarily ground-based navigation with robust satellite-enabled air traffic procedures and to supplement ground-based air …

Indeterminate Masses, Elements And Models In Information Fusion, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

In this paper at the beginning, we make a short history of the logics, from the classical Boolean logic to the most general logic of today neutrosophic logic. We define the general logic space and give the definition of the neutrosophic logic. Then we introduce the indeterminate models in information fusion, which are due either to the existence of some indeterminate elements in the fusion space or to some indeterminate masses.

The best approach for dealing with such models is the neutrosophic logic, which is part of neutrosophy. Neutrosophic logic is connected with neutrosophic set and neutrosophic probability and statistics.

Heteroclinic And Homoclinic Connections Between The Sun-Earth Triangular Points And Quasi-Satellite Orbits For Solar Observations, Pedro J. Llanos, Gerald R. Hintz, Martin W. Lo, James K. Miller

Publications

Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP (circular restricted three-body problem) in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. …

Discussion Of Christine C. Shepard, Vera N. Agostini, Ben Gilmer, Tashya Allen, Jeff Stone, William Brooks And Michael W. Beck. Reply: Evaluating Alternative Future Sea-Level Rise Scenarios, Natural Hazards, 2012 Doi:10.1007/S11069-012-0160-2, A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Hybrid Protocols For Maintaining Connectivity Of Multiagent Systems, Gerardo De La Torre, Tansel Yucelen, Eric N. Johnson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper focuses on a new connectivity control architecture for networked multiagent systems based on hybrid protocols. Specifically, for a group of agents subject to Δ-disk proximity graphs, we consider the consensus problem while preserving connectedness with a priori given bounds on the control inputs. The bounds on the control inputs are shown not to depend on potential functions or system states. Instead, the bounds are user selected continuous functions. By using the proposed framework, we show that the maximum distance among neighboring agents decreases strictly, and hence the connectivity problem is solved while satisfying the consensus objective. © 2013 …

An Attitude Determination System With Mems Gyroscope Drift Compensation For Small Satellites, Maxwell Bezold

Theses and Dissertations--Electrical and Computer Engineering

This thesis presents the design of an attitude determination system for small satellites that automatically corrects for attitude drift. Existing attitude determination systems suffer from attitude drift due to the integration of noisy rate gyro sensors used to measure the change in attitude. This attitude drift leads to a gradual loss in attitude knowledge, as error between the estimated attitude and the actual attitude increases.

In this thesis a Kalman filter is used to complete sensor fusion which combines sensor observations with a projected attitude based on the dynamics of the satellite. The system proposed in this thesis also utilizes …

Visual Attitude Propagation For Small Satellites, Samir Ahmed Rawashdeh

Theses and Dissertations--Electrical and Computer Engineering

As electronics become smaller and more capable, it has become possible to conduct meaningful and sophisticated satellite missions in a small form factor. However, the capability of small satellites and the range of possible applications are limited by the capabilities of several technologies, including attitude determination and control systems. This dissertation evaluates the use of image-based visual attitude propagation as a compliment or alternative to other attitude determination technologies that are suitable for miniature satellites. The concept lies in using miniature cameras to track image features across frames and extracting the underlying rotation.

The problem of visual attitude propagation as …

Assess The Accuracy Of The Variational Asymptotic Plate And Shell Analysis Using The Generalized Uni, Luciano Demasi, Wenbin Yu

Mechanical and Aerospace Engineering Faculty Publications

The accuracy of the Variational Asymptotic Plate and Shell Analysis (VAPAS) is assessed against several higher order, zig zag and layerwise theories generated by using the invariant axiomatic framework denoted as Generalized Unified Formulation (GUF). These theories are also compared against the elasticity solution developed for the case of a sandwich structure with high Face to Core Stiffness Ratio. GUF allows to use an infinite number of axiomatic theories (Equivalent Single Layer theories with or without zig zag effects and Layerwise theories as well) with any combination of orders of the displacements and it is an ideal tool to precisely …

Prediction Of Foreign Object Debris/Damage (Fod) Type For Elimination In The Aeronautics Manufacturing Environment Through Logistic Regression Model, Natalia V. Espino

Open Access Theses & Dissertations

Foreign Object Debris/Damage (FOD) is a costly and high-risk problem that aeronautics industries such as Boeing, Lockheed Martin, among others are facing at their production lines every day. They spend an average of $350 thousand dollars per year fixing FOD problems. FOD can put pilots, passengers and other crews' lives into high-risk. FOD refers to any type of foreign object, particle, debris or agent in the manufacturing environment, which could contaminate/damage the product or otherwise undermine quality control standards. FOD can be in the form of any of the following categories: panstock, manufacturing debris, tools/shop aids, consumables and trash. Although …