Aerospace Engineering Commons^™

On The Selection Of A Good Shape Parameter For Rbf Approximation And Its Application For Solving Pdes, Lei-Hsin Kuo

Dissertations

Meshless methods utilizing Radial Basis Functions~(RBFs) are a numerical method that require no mesh connections within the computational domain. They are useful for solving numerous real-world engineering problems. Over the past decades, after the 1970s, several RBFs have been developed and successfully applied to recover unknown functions and to solve Partial Differential Equations (PDEs).
However, some RBFs, such as Multiquadratic (MQ), Gaussian (GA), and Matern functions, contain a free variable, the shape parameter, c. Because c exerts a strong influence on the accuracy of numerical solutions, much effort has been devoted to developing methods for determining shape parameters which provide …

Similarity Analysis Of A Swirling Counter-Flow, Jitesh Rane

Doctoral Dissertations and Master's Theses

Swirling counter-flows are used in numerous engineering applications, like combustion, heat exchangers, cyclonic separation and mixing, etc. These swirling counter-flows produce complex flow fields. It is important to study these types of flows in order to use them properly in many applications.

The present work provides insight into the flowfield inside a swirling counter-flow when the fluid is injected tangentially in a cylindrical container. A semi-analytical solution is developed by starting with the full Navier-Stokes equation and using a similarity analysis. A decaying swirl along the axis of the cylinder is assumed, which reduces the Navier-Stokes equations to first order …

Consensus With Reduced Communication Links Via Relative Neighboring Velocity Information, Gerardo De La Torre, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, a consensus protocol is introduced to virtually manipulate the communication topology of a given networked multiagent system - without adding physical edges to the graph. The proposed protocol achieves this objective by utilizing not only neighboring agents' relative position information but also their possibly delayed velocity information. It is shown that the stability of the proposed framework is not dependent on the possible time delay present in the neighboring velocity information. In addition, it is formally proven that utilization of the proposed consensus protocol is equivalent to the addition of virtual communication links in a standard consensus …

Adaptive Control With Nonlinear Reference Systems, Tansel Yucelen, Benjamin Gruenwald, Jonathan A. Muse, Gerardo De La Torre

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although reference systems with linear dynamics are common in the adaptive control literature, they can lead to limitations on the achievable closed-loop dynamical system performance. This is due to the fact that linear reference systems can only approximate the desired closed-loop behavior of nonlinear dynamical systems in narrow regions of the state-space. In this paper, we study a new adaptive control architecture for uncertain dynamical systems based on a nonlinear reference system. It is shown that the system error between the uncertain dynamical system and the nonlinear reference system asymptotically vanishes in steady-state, and its performance is guaranteed during the …

Exploitation Of Heterogeneity In Distributed Sensing: An Active-Passive Networked Multiagent Systems Approach, John Daniel Peterson, Tansel Yucelen, Girish Chowdhary, Suresh Kannan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Most distributed sensing methods assume that the expected value of sensed information is same for all agents - ignoring differences in sensor capabilities due to, for example, environmental factors and sensors' quality and condition. In this paper, we present a distributed sensing framework to exploit heterogeneity in information provided about a dynamic environment using an active-passive networked multiagent systems approach. Specifically, this approach consists of agents subject to exogenous inputs (active agents) and agents without any inputs (passive agents). In addition, if an active agent senses a quantity accurately (resp., not accurately), then it is weighted high (resp., low) in …

Analysis And Design Of Adaptive Control Systems With Unmodeled Input Dynamics Via Multiobjective Convex Optimization, Mario Luca Fravolini, Tansel Yucelen, Jonathan Muse, Paolo Valigi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A challenging problem for adaptive control systems is the accurate characterization of the transient response in the presence of dynamic uncertainties such as a partially known actuator. Considering an actuator modelled as a first order filter with an uncertain control effectiveness and using a projection mechanism for parameters adaptation, we show that the tracking error dynamics behaves as a linear system perturbed by bounded uncertainties. This brings the advantage that the stability analysis can be cast in terms of LMIs so that convex optimization tools can be used for analysis and design. In this framework we propose a mixed linear/adaptive …

Exploring New Lagrangian Cyclers To Enhance Science: Communications With Cubesat Technology, Pedro P. Llanos, Abdiel Santos Galindo, John Ford

Publications

This paper discusses the opportunities that abound by using the CubeSat technology to travel to and communicate with the International Space Station, explore space, monitor space weather, monitor space debris and perhaps travel to Mars.

The Robert & Esther Goddard Papers, Robert H. Goddard

Finding Aids

Dr. Robert H. Goddard was a member of the Clark Physics Department for 29 years. Foremost American pioneer of rocket research, he laid the technical and theoretical foundations for many of the developments in long-range rockets, missiles, satellites and space flight, which collectively put us into the Space Age.

The collection includes correspondence, diaries, journals, patent applications and awards, reports, and photographs. The collection also includes original paintings by Dr. Goddard.

Bio-Fuel Alternatives In South African Airways (Saa) Operations - Is It An Effective Response To Vulnerability Over Carbon Taxes And Penalty?, Daniel Kwasi Adjekum

International Journal of Aviation, Aeronautics, and Aerospace

The paper did a comparative analysis of the carbon emission and European Union Emission Trading Surcharges (EU ETS) of South African Airways (SAA) current fleet that used aviation jet A1 fuel and the same fleet if it had used a 25% bio-fuel ‘drop in’ for the European routes within the first quarter of the 2014 flying year (FY 14). Operational data in terms of the flight scheduled, aircraft type, total time enroute, route stage length, passenger estimates were obtained through SAA’s flight operations website. An independent t–test was conducted to compare means of the emissions. The mean carbon dioxide …

How To Save The World: One Life (And Uav) At A Time!, Natalie A. Wright

STAR Program Research Presentations

The proliferation of Uninhabited Aerial Vehicles (UAV’s) in commercial and public service aviation arenas has begun to gain the attention of many citizens. Popularized vehicles such as quadcopters have applications in aerial photography, small package delivery and hobbyist/consumer interests. Use of small-scale, fixed- and rotary-wing, remotely operated systems has been popularized as a result of such vehicles’ size and operational simplicity, which widens the range of application of this technology. Public service applications have the potential to advance emergency services management, which can substantially contribute to the public wellbeing. This research will examine the utility of multi-rotor systems in the …

Evaluation Of Different Optimal Control Problem Formulations For Solving The Muscle Redundancy Problem, Friedl De Groote, Allison Kinney, Anil Rao, Benjamin J. Fregly

Mechanical and Aerospace Engineering Faculty Publications

This study evaluates several possible optimal control problem formulations for solving the muscle redundancy problem with the goal of identifying the most efficient and robust formulation. One novel formulation involves the introduction of additional controls that equal the time derivative of the states, resulting in very simple dynamic equations. The nonlinear equations describing muscle dynamics are then imposed as algebraic constraints in their implicit form, simplifying their evaluation. By comparing different problem formulations for computing muscle controls that can reproduce inverse dynamic joint torques during gait, we demonstrate the efficiency and robustness of the proposed novel formulation.

Bio-Fuel Alternatives In South African Airways (Saa) Operations - Is It An Effective Response To Vulnerability Over Carbon Taxes And Penalty?, Daniel Kwasi Adjekum

Aviation Faculty Publications

The paper did a comparative analysis of the carbon emission and European Union Emission Trading Surcharges (EU ETS) of South African Airways (SAA) current fleet that used aviation jet A1 fuel and the same fleet if it had used a 25% bio-fuel ‘drop in’ for the European routes within the first quarter of the 2014 flying year (FY 14). Operational data in terms of the flight scheduled, aircraft type, total time enroute, route stage length, passenger estimates were obtained through SAA’s flight operations website. An independent t–test was conducted to compare means of the emissions. The mean carbon dioxide …

Flight Dynamics Nonlinearity Assessment Across A New Aerodynamic Attitude Flight Envelope, Ayman Muhammad Abdallah

Mechanical & Aerospace Engineering Theses & Dissertations

A new asymmetric level aerodynamic attitude flight envelope is introduced in this dissertation. The aerodynamic attitude envelope is an angle of attack vs. sideslip angle region which describes the extent of where an aircraft can sustain a steady slipping horizontal flight condition. The new envelope is thus an extension of the more common speed-altitude symmetric level flight envelope. This new envelope can be used for design requirements, dynamic analysis, control synthesis, or performance comparison. Moreover, this envelope provides enhanced insight into trimability-controllability limitations within the aircraft design model. The aerodynamic attitude flight envelope is constructed for a six degree of …

Nano Scale Mechanical Analysis Of Biomaterials Using Atomic Force Microscopy, Diganta Dutta

Mechanical & Aerospace Engineering Theses & Dissertations

The atomic force microscope (AFM) is a probe-based microscope that uses nanoscale and structural imaging where high resolution is desired. AFM has also been used in mechanical, electrical, and thermal engineering applications. This unique technique provides vital local material properties like the modulus of elasticity, hardness, surface potential, Hamaker constant, and the surface charge density from force versus displacement curve. Therefore, AFM was used to measure both the diameter and mechanical properties of the collagen nanostraws in human costal cartilage. Human costal cartilage forms a bridge between the sternum and bony ribs. The chest wall of some humans is deformed …

Self-Organization Of Protein Fibers In Weightlessness, Dylan Bell

Theses and Dissertations

It is currently hypothesized and widely believed that the growth of self aggregating protein chains such as amyloid fibers has a direct effect on the function of the human brain. We hypothesized creating self-assembling protein in weightlessness would allow the aggregation to continue for a longer period of time in solution without sedimentation. When protein de-natures and self-organizes into amyloid fibers the effect can be detrimental. Some neurodegenerative diseases, such as Alzheimer’s and Dementia, are believed to be caused by the collection of these fibers made from proteins such as tau and amyloid-β. For the purpose of this experiment, lysozyme …

Development Of An Interactive Wave Drag Capability For The Openvsp Parametric Geometry Tool, Michael Jon Waddington

Master's Theses

Minimizing wave drag is critical to successful and efficient transonic and supersonic flight. Area-ruling is the process of managing the cross-sectional area of an aircraft to lessen the wave drag experienced in flight. Effectively calculating the necessary areas for a given aircraft can be difficult, and existing tools for conducting a wave drag analysis often carry limitations in both functionality and availability.

In this work, the author utilized an existing parametric geometry tool named OpenVSP to create an interactive design tool for approximating zero-lift wave drag. Here, the wave drag calculation methodology used in industry for decades is combined with …

Directional Camera Control On High Altitude Balloons, Matthew M. Plewa, Brent Scharlau

2017 Academic High Altitude Conference

The research reported in this paper examined the design and control of a gimbal for solar eclipse tracking and video recording. The gimbal design required 3 axes of rotation to allow for full range of motion. Utilizing individual brushless motors for each of the axes ensure minimum rotational requirements on each axes. In controlling the gimbal, both a mathematical and visual method were utilized. The mathematical method is a modified version of what is currently used for solar array pointing. The visual method looks at where the position of the sun is within the image and determines what angle changes …

An Overview Of A Solar Eclipse Video Payload, Alexander M. Peters

2017 Academic High Altitude Conference

The HABET group at Iowa State University has been designing and building balloon payloads for years, giving students hands on experience with the engineering involved in creating and launching payloads to near space conditions. After attending the AHAC conference in 2014 the group begain to design a balloon for the 2017 solar eclipse. Working closely with the Space Grant Consortium’s design team, HABET has designed and completed preliminary testing on a Solar Eclipse Video payload. This payload uses multiple subsystems to complete the mission. The mission required an altitude control system, live video downlink, and a camera pointing system. Our …

Computational Fluid Dynamics Study Of Balloon System Tethered To A Stratosail, Jayakanth Loganathan, Kian-Meng Lim, Heow Pueh Lee, Boo Cheong Khoo

2017 Academic High Altitude Conference

In this paper, we present a numerical study of a stratospheric balloon system tethered to a passive device, known as the Stratosail, for station-keeping operation. For scientific applications, stratospheric balloons that operate at altitudes between 15 and 20 km will need to maintain station over a fixed point above the earth for a prescribed period of time. This is a challenging problem due to the limitation of payloads and lack of an energy source. The present study uses computational fluid dynamics (CFD) simulations to analyze the drift velocity of such a balloon-Stratosail system under typical wind conditions in the stratosphere. …

Techniques For Payload Stabilization For Improved Photography During Stratospheric Balloon Flights, James Flaten, Christopher Gosch, Joseph (Benjamin) Habeck

2017 Academic High Altitude Conference

Payload-box rotation and swing are perennial challenges to achieving high-quality photography (typically videography) during weather-balloon flights to “near-space” (AKA the stratosphere). Continuous camera motion can lead to blurred still photos, nearly-impossible-to-watch video footage, and precludes time-exposure photography required for most astronomical imaging even though altitudes are reached where the daytime sky appears black. Apparently-random payload rotation, persisting even at altitude, can often exceed servo rotation rates and frustrate attempts to do active camera pointing. Here we discuss mostly-passive payload stabilization strategies we, and our collaborators, have used to mitigate and dampen both swing and rotation of suspended payloads on high-altitude …