Aerospace Engineering Commons^™

Fleet Level Environmental Evaluation Of Emission Taxing Scheme And Biofuel: A Combined Optimization And Multi-Actor Approach, Hsun Chao

Open Access Theses

The Fleet Level Environmental Evaluation Tool (FLEET) can assess environmental impacts of various levels of technology and environmental policies on fleet-level carbon emissions and airline operations. FLEET consists of different models to mimic airlines' behaviors and a resource allocation problem to simulate airlines' aircraft deployments on their networks. Additionally, the Multiactors Biofuel Model can conduct biofuel life-cycle assessments and evaluate biofuel developments and assess the effects of new technology on biofuel production costs and unit carbon emissions as well.

In addition, the European Union (EU) initiated an Emission Trading Scheme (ETS) in the European Economic Area, while International Civil Aviation …

Ab Initio Based State Specific Modeling Of N2+O System, Han Luo

Open Access Theses

Nitrogen and atomic oxygen play an important role in high temperature gas systems. Their Zeldovich reaction product nitric oxide not only affects aerothermal loads and emissions of hypersonic vehicles, but also has the possibility to influence the efficiency of hypersonic propulsion. Atomic oxygen induced nitrogen dissociation is another reaction mechanism of the N2+O system. However, due to the difficulty of conducting ground tests, there are no experimental data for this reaction now. Thermo-chemical nonequilibrium could make the problem more difficult since experiments could only track macroscopic gas properties instead of internal energy distribution. On the other hand, current reaction and …

Supporting Space Systems Design Via Systems Dependency Analysis Methodology, Cesare Guariniello

Open Access Dissertations

The increasing size and complexity of space systems and space missions pose severe challenges to space systems engineers. When complex systems and Systems-of-Systems are involved, the behavior of the whole entity is not only due to that of the individual systems involved but also to the interactions and dependencies between the systems. Dependencies can be varied and complex, and designers usually do not perform analysis of the impact of dependencies at the level of complex systems, or this analysis involves excessive computational cost, or occurs at a later stage of the design process, after designers have already set detailed requirements, …

Information Inference For Cyber-Physical Systems With Application To Aviation Safety And Space Situational Awareness, Sangjin Lee

Open Access Dissertations

Due to the rapid advancement of technologies on sensors and processors, engineering systems have become more complex and highly automated to meet ever stringent performance and safety requirements. These systems are usually composed of physical plants (e.g., aircraft, spacecraft, ground vehicles, etc.) and cyber components (e.g., sensing, communication, and computing units), and thus called as Cyber-Physical Systems (CPSs). For safe, efficient, and sustainable operation of a CPS, the states and physical characteristics of the system need to be effectively estimated or inferred from sensing data by proper information inference algorithms. However, due to the complex nature of the interacting multiple-heterogeneous …

Physical Properties, Evaporation And Combustion Characteristics Of Nanofluid-Type Fuels, Saad Tanvir

Open Access Dissertations

Nanofluids are liquids with stable suspension of nanoparticles. Limited studies in the past have shown that both energetic and catalytic nanoparticles once mixed with traditional liquid fuels can be advantageous in combustion applications, e.g., increased energy density and shortened ignition delay. Contradictions in existing literature, scarcity of experimental data and lack of understanding on how the added nanoparticles affect the physical properties as well as combustion characteristics of the resulting fuel motivated us to launch a detailed experimental and theoretical investigation.

The surface tension of ethanol and n-decane based nanofluid fuels containing suspended nanoparticles were measured using the pendant drop …

Analytical Methods For Gravity-Assist Tour Design, Nathan J. Strange

Open Access Dissertations

This dissertation develops analytical methods for the design of gravity-assist space- craft trajectories. Such trajectories are commonly employed by planetary science missions to reach Mercury or the Outer Planets. They may also be used at the Outer Planets for the design of science tours with multiple flybys of those planets’ moons. Recent work has also shown applicability to new missions concepts such as NASA’s Asteroid Redirect Mission.

This work is based in the theory of patched conics. This document applies rigor to the concept of pumping (i.e. using gravity assists to change orbital energy) and cranking (i.e. using gravity assists …

Implementing And Testing A Panel-Based Method For Modeling Acoustic Scattering From Cfd Input, S. Hales Swift

Open Access Dissertations

Exposure of sailors to high levels of noise in the aircraft carrier deck environment is a problem that has serious human and economic consequences. A variety of approaches to quieting exhausting jets from high-performance aircraft are undergoing development. However, testing of noise abatement solutions at full-scale may be prohibitively costly when many possible nozzle treatments are under consideration. A relatively efficient and accurate means of predicting the noise levels resulting from engine-quieting technologies at personnel locations is needed. This is complicated by the need to model both the direct and the scattered sound field in order to determine the resultant …

The Validation And Verification Of Les Modeling Using Kiva, David Fyda

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, the use of large-eddy simulation (LES) has grown into new research methods. LES is preferred when compared to Reynold’s Averaged Navier Stokes (RANS), which separates velocity components into steady and fluctuating components. While RANS is relatively easy to implement, it does not fully resolve the range of turbulence eddies and has limitations that make it inaccurate in many practical circumstances. Direct numerical simulation, DNS, fully resolves all turbulent eddies to the smallest grid scale, but requires an extremely fine grid. This makes it computationally impractical to use as the computational power required to solve even the simplest …

Enhanced Thermal Conductance Of Polymer Composites Through Embedding Aligned Carbon Nanofibers, David S. Wood, Dale K. Hensley, Nicholas A. Roberts

Mechanical and Aerospace Engineering Faculty Publications

The focus of this work is to find a more efficient method of enhancing the thermal conduc-tance of polymer thin films. This work compares polymer thin films embedded with randomly oriented carbon nanotubes to those with vertically aligned carbon nanofibers. Thin films embedded with carbon nanofibers demonstrated a similar thermal conductance between 40–60 µm and a higher thermal con-ductance between 25–40 µm than films embedded with carbon nanotubes with similar volume fractions even though carbon nanotubes have a higher thermal conductivity than carbon nanofibers.

Detecting Delamination In Carbon Fiber Composites Using Piezoresistive Nanocomposites, Sandeep Chava

Doctoral Dissertations and Master's Theses

Carbon fiber prepreg composites are utilized successfully as structural materials for different lightweight aerospace applications. Delamination is a critical failure mode in these composite materials. As composite plies separate from each other, the composite loses some of its ability for supporting expected loads. Therefore, detection of delamination at right time is a foremost significance. This study presents a new way for detecting delamination in composite plates using piezoresistive nanocomposites. This new procedure is setup and studied through both experimental and computational investigations. In this research, nanocomposites with 5% coarse graphene platelets are fabricated for detecting delamination. 8-ply carbon fiber prepreg …

Vision-Aided Navigation For Autonomous Vehicles Using Tracked Feature Points, Ahmed Saber Soliman Sayem

Doctoral Dissertations and Master's Theses

This thesis discusses the evaluation, implementation, and testing of several navigation algorithms and feature extraction algorithms using an inertial measurement unit (IMU) and an image capture device (camera) mounted on a ground robot and a quadrotor UAV. The vision-aided navigation algorithms are implemented on data-collected from sensors on an unmanned ground vehicle and a quadrotor, and the results are validated by comparison with GPS data. The thesis investigates sensor fusion techniques for integrating measured IMU data with information extracted from image processing algorithms in order to provide accurate vehicle state estimation. This image-based information takes the forms of features, such …

Multiplex Information Networks For Spatially Evolving Multiagent Formations, Dung Tran, Tansel Yucelen, Eduardo Pasiliao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we show how information exchange rules represented by a network having multiple layers (multiplex information networks) can be designed for enabling spatially evolving multiagent formations. Specifically, we consider the formation tracking problem and introduce a novel distributed control architecture. The proposed approach allows capable agents to spatially alter density and orientation of the resulting formation while tracking a dynamic, non-stationary target without requiring global information exchange ability. A numerical example is provided to illustrate the efficacy of the proposed distributed control architecture.

Generalizations On Active-Passive Dynamic Consensus Filters, J. Daniel Peterson, Tansel Yucelen, Eduardo Pasiliao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Active-passive dynamic consensus filters consist of agents subject to local observations of a process of interest (active agents) and agents without any observations (passive agents). In this paper, we introduce a new class of active-passive dynamic consensus filters using results from graph theory and systems science. Specifically, the proposed filters only require agents to exchange their current state information with neighbors in a simple and isotropic manner to reduce the overall information exchange cost of the network. In addition, we allow the roles of active and passive agents to be time-varying for making these filters suitable for a wide range …

Adaptive Control Architectures For Mitigating Sensor Attacks In Cyber-Physical Systems, Tansel Yucelen, Wassim M. Haddad, Eric M. Feron

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The accuracy of sensor measurements is critical to the design of high-performance control systems since sensor uncertainties can significantly deteriorate achievable closed-loop dynamical system performance. Sensor uncertainty can arise due to low sensor quality, sensor failure, or detrimental environmental conditions. For example, relatively cheap sensor suites are used for low-cost, small-scale unmanned vehicle applications that can result in inaccurate sensor measurements. Alternatively, sensor measurements can also be corrupted by malicious attacks if dynamical systems are controlled through large-scale, multilayered communication networks as is the case in cyber-physical systems. This paper presents several adaptive control architectures for stabilization of linear dynamical …

Mitigating The Effects Of Sensor Uncertainties In Networked Multiagent Systems, Ehsan Arabi, Tansel Yucelen, Wassim M. Haddad

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Networked multiagent systems consist of interacting agents that locally exchange information, energy, or matter. Since they do not in general have a centralized entity to monitor the activity of each agent, resilient distributed control system design for networked multiagent systems is essential in providing high system performance, reliability, and operation in the presence of system uncertainties. An important class of such system uncertainties that can significantly deteriorate the achievable closed-loop system performance is sensor uncertainties, which can arise due to low sensor quality, sensor failure, sensor bias, or detrimental environmental conditions. This paper presents a novel distributed adaptive control architecture …

A New Model Reference Control Architecture: Stability, Performance, And Robustness, Gerardo De La Torre, Tansel Yucelen, Eric N. Johnson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we develop a new model reference control architecture to effectively suppress system uncertainties and achieve a guaranteed transient and steady-state system performance. Unlike traditional robust control frameworks, only a parameterization of the system uncertainty given by unknown weights with known conservative bounds is needed to stabilize uncertain dynamical systems with predictable system performance. In addition, the proposed architecture's performance is not dependent on the level of conservatism of the bounds of system uncertainty. Following the same train of thought as adaptive controllers that modify a given reference system to improve system performance, the proposed method is inspired …

Suppressing Restricted Shock Separation In A Subscale Rocket Nozzle Using Contour Geometry, K. Schomberg, J. Olsen, A. J. Neely, Graham Doig

Aerospace Engineering

The use of a thrust-optimized contour (TOC) for the supersonic nozzle in a rocket engine will inherently maximize the propulsive efficiency and payload capacity of the entire launch system. A TOC can be approximated using a skewed parabola, commonly referred to as a thrust-optimized parabola (TOP), and the TOP contour can be manipulated to avoid undesirable flow separation during low-altitude operation by increasing the static wall pressure at the expense of thrust (approximately 0.1 0.2%). For this reason, a TOP design is often used in nozzles with a high area ratio, such as those used in the Vulcain and Vulcain …

Optimization Of Takeoffs On Unbalanced Fields Using Takeoff Performance Tool, Nihad E. Daidzic

International Journal of Aviation, Aeronautics, and Aerospace

Unbalanced field length exists when ASDA and TODA are not equal. Airport authority may add less expensive substitutes to runway full-strength pavement in the form of stopways and/or clearways to basic TORA to increase operational takeoff weights. Here developed Takeoff Performance Tool is a physics-based total-energy model used to simulate FAR/CS 25 regulated airplane takeoffs. Any aircraft, runway, and environmental conditions can be simulated, while complying with the applicable regulations and maximizing performance takeoff weights. The mathematical model was translated into Matlab, Fortran 95/2003/2008, Basic, and MS Excel computer codes. All existing FAR/CS 25 takeoff regulations are implemented. Average forces …

Suitability Testing For Possum Scientist-Astronaut Candidates Using The Suborbital Space Flight Simulator With An Iva Spacesuit, Pedro J. Llanos, Erik Seedhouse, Ryan L. Kobrick

Publications

This paper evaluates key functional data parameters that must be considered for suborbital spaceflight participants wearing pressurized suits for intravehicular activity (IVA). Data parameters of an analog spacesuit worn in an analog flight environment were obtained from 40 civilian participants using the Suborbital Space Flight Simulator (SSFS) at Embry-Riddle Aeronautical University (ERAU) while donning Final Frontier Design’s (FFD) fully pressurized third-generation spacesuit as part of their training for Project PoSSUM (the Polar Suborbital Science in the Upper Mesosphere Project). The physiological data collected included: blood pressure, electrocardiograms, heart rate, grip strength, and skin temperature. These parameters were measured using a …

Standardization Of Human-Computer-Interface For Geo-Fencing In Small Unmanned Aircraft Systems, David Thirtyacre, Robert Brents, Michael Goldfein, David Hunter, B. Terwilliger

Publications

The use of small unmanned aircraft systems (sUAS) has increased significantly in the past year. Geographic fencing (geo-fencing) is software built into most medium-cost consumer sUAS. This software is typically used to limit the altitude above launch point, the flight distance from the transmitting controller, and/or restrict flight inside a no-fly zone. While the concept of a geo-fence is simplistic, the human-computer-interface (HCI) varies drastically among platforms, and even between software iterations on the same platform. This research examines the HCI of three popular consumer-level sUAS with regard to geo-fencing. The software procedures and human interface for the DJI Inspire-1, …