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Stability Analysis Of A More General Class Of Systems With Delay-Dependent Coefficients, Chi Jin, Keqin Gu, Islam Boussaada, Silviu-Iulian Niculescu 2019 Laboratoire des Signaux et Syst`emes (L2S) CentraleSup´elec-CNRS-Universit´e Paris Sud, 3 rue Joliot- Curie 91192 Gif-sur-Yvette cedex, France.

Stability Analysis Of A More General Class Of Systems With Delay-Dependent Coefficients, Chi Jin, Keqin Gu, Islam Boussaada, Silviu-Iulian Niculescu

SIUE Faculty Research, Scholarship, and Creative Activity

This paper presents a systematic method to analyse the stability of systems with single delay in which the coefficient polynomials of the characteristic equation depend on the delay. Such systems often arise in, for example, life science and engineering systems. A method to analyze such systems was presented by Beretta and Kuang in a 2002 paper, but with some very restrictive assumptions. This work extends their results to the general case with the exception of some degenerate cases. It is found that a much richer behavior is possible when the restrictive assumptions are removed. The interval of interest for the ...


Plume Contamination Measurements Of An Additively-Printed Gox/Abs Hybrid Thruster, David A. Brewer 2018 Utah State University

Plume Contamination Measurements Of An Additively-Printed Gox/Abs Hybrid Thruster, David A. Brewer

All Graduate Theses and Dissertations

This thesis examines the impact of the physical contamination on optical surfaces of spacecraft by an ABS/GOX thruster. Plume contamination presents a significant operational hazard for spacecraft solar arrays and thermal control surfaces can lead to decreased power production and increased spacecraft temperatures. Historically, due to the lack of a reliable, on-demand, and multiple-use ignition methodology, hybrid rockets have never been previously considered for in-space propulsion. Recent advancements in hybrid rocket technologies, have made hybrid systems feasible for in space propulsion. However, prior to this study no research had ever been performed with regard to plume contamination effects due ...


A Non-Equilibrium Molecular Dynamics Study Of The Effects Of Helium Bubbles On The Thermal Conductivity Of Zrc, Tate Shorthill 2018 Utah State University

A Non-Equilibrium Molecular Dynamics Study Of The Effects Of Helium Bubbles On The Thermal Conductivity Of Zrc, Tate Shorthill

All Graduate Plan B and other Reports

Zirconium carbide (ZrC) has been proposed as a potential improvement to nuclear fuel cladding. As such, it is important to characterize its physical properties, particularly those relating to thermal energy transport. Reactor conditions are known to damage fuel microstructure over time. While research has been conducted on undamaged and damaged ZrC, some areas of interest remain. Fission products, such as helium, can accumulate in pores within the fuel microstructure. Such a case has yet to be characterized in ZrC fuel cladding.

A non-equilibrium molecular dynamics model was developed to characterize the thermal properties of ZrC. Fourier’s Law allows the ...


Book Review: Fundamentals Of International Aviation, Alan Bender 2018 Embry-Riddle Aeronautical University - Worldwide

Book Review: Fundamentals Of International Aviation, Alan Bender

International Journal of Aviation, Aeronautics, and Aerospace

Not applicable.


Competitiveness Of Hybrid Electric Aircraft On Short Range Scheduled Flights, Johannes Anton, Hans-Joachim K. Ruff-Stahl 2018 Embry-Riddle Aeronautical University

Competitiveness Of Hybrid Electric Aircraft On Short Range Scheduled Flights, Johannes Anton, Hans-Joachim K. Ruff-Stahl

International Journal of Aviation, Aeronautics, and Aerospace

Hybrid electric aircraft are expected to enter the small regional aircraft market within the next two decades. The aim of this study was to investigate if a hybrid electric passenger aircraft with 50 seats can be competitive against the established 100 seat aircraft on short range scheduled flights. The Embraer EMB 145 and EMB 190 regional jets were chosen as benchmarks for that market. A hypothetical hybrid version of the EMB 145 with increased fuel efficiency was tested on a cost per available seat mile (CASM) basis. The t tests confirmed significant (p < 0.05) competitiveness of the hybrid version, while in contrast the conventional 50-seater was significantly more expensive compared to the 100seat aircraft. This indicates that hybrid aircraft could enter the short haul market with a competitive advantage, even against the established 100 seat regional jets.


Development Of Digital Diary For Enhanced Parental School Involvement In Tanzania, Sekione R. Jeremiah, Joel S. Mtebe PhD 2018 University of Dar es Salaam

Development Of Digital Diary For Enhanced Parental School Involvement In Tanzania, Sekione R. Jeremiah, Joel S. Mtebe Phd

The African Journal of Information Systems

The study examined the use of digital diary as a tool for enhancing parental school involvement in Tanzania. The development of the digital diary followed eXtreme Programming agile method where 87 parents and 6 teachers from St. Florence school were involved. Parents and teachers were given six months to use the tool before testing for its effectiveness using data from 7 teachers and 156 parents through semi-structured interviews and questionnaires respectively. The study found that the majority of respondents (84.4% of parents and 96.7% of teachers) indicated that the digital diary was useful tool as enabled them to ...


Thermally Stable Super-Hydrophobic Surface Creation, Caleb Turner 2018 Portland State University

Thermally Stable Super-Hydrophobic Surface Creation, Caleb Turner

Undergraduate Research & Mentoring Program

Thermally stable super-hydrophobic surface coatings are critical to applications in low gravity fluid dynamics, and in particular Leidenfrost effects. The challenges of manufacturing different super-hydrophobic coatings that are thermally stable, semi-transparent, and environmentally safe at desired operating temperatures is pursued in order to explore the applications of such coatings aboard spacecraft. A catalog of surface coating manufacturing procedures is tabulated with measures for static contact angle, thermal stability, and transparency. These quantities and methods serve as a foundation for both technology applications and follow on experimentation concerning low gravity fluid mechanics at the Portland State Dryden Drop Tower lab.


Electric Aircraft And The Environment: A Literature Review, Uyen T. Sou 2018 San Jose State University

Electric Aircraft And The Environment: A Literature Review, Uyen T. Sou

McNair Research Journal SJSU

Historically, the integration of social need, environmental impact, and technological advancement has been a challenging balancing act for growing cities and metropoles. If the balance between social need and environmental sustainability is reached, the increasing advancements and improvements made to electric aircrafts have the potential to steer society towards a new mode of sustainable air. One reason why electric aircraft technology has not grown as fast as other technologies is because there lacked a need for fast advancements. With that said, electric aircraft technologies are improving today due to the demand in heavily populated cities to relieve traffic [5]. Some ...


Nasa Microgravity: Internal Structure And Recovery Method Optimization, Brenna Doherty 2018 University of Wyoming

Nasa Microgravity: Internal Structure And Recovery Method Optimization, Brenna Doherty

Honors Theses AY 17/18

Microgravity is defined as a state of having very little gravity, such as that experienced in space. Research has been performed by NASA for over 25 years as a way to determine how space technologies are impacted by a microgravity environment. To simulate microgravity, an aerodynamic payload is dropped in a vacuum chamber or from high altitudes until a state of freefall is reached. NASA drop towers are the standard microgravity testing platforms used today. These towers can produce microgravity environments for 2.2-5.2 seconds; however, these platforms are expensive and require months of advanced planning. The University of ...


Non-Linear Controls Project Report, Rachit Bhatia 2018 Utah State University

Non-Linear Controls Project Report, Rachit Bhatia

Rachit Bhatia

This article is a review of the paper titled “A Globally Stable Lyapunov Pointing and Rate Controller for
the Magnetospheric MultiScale Mission (MMS)” by Neerav Shah (2011).1 Here, an attempt has been made
to replicate the results from the paper by Shah (2011), and an interpretation of the results has been presented,
in the light of the theoretical background covered in the Non-Linear controls course (MAE7730).


Propulsive Battery Packs Sizing For Aviation Applications, Tianyuan Zhao 2018 Embry-Riddle Aeronautical University

Propulsive Battery Packs Sizing For Aviation Applications, Tianyuan Zhao

Dissertations and Theses

This thesis derives analytical methods for sizing the propulsive battery packs for designing an electric-driven aircraft. Lithium-Ion (Li-Ion) battery is the primary choice of battery cell chemistry in this thesis research due to its superior specific energy and market availability. The characteristics of Lithium-Ion battery cells are first determined and studied using experimental test results and manufacturers published data. Based on the design requirement to the battery system, the battery sizing will fall into one of the two sizing categories. The first category is power sizing, which requires the battery’s ability to deliver full power demanded by the electric ...


Numerical Simulation Of Shock Wave Propagation In Ducts With Grooves, Seyed Mehdi Mortazawy 2018 Embry-Riddle Aeronautical University

Numerical Simulation Of Shock Wave Propagation In Ducts With Grooves, Seyed Mehdi Mortazawy

Dissertations and Theses

The pressure attenuation of moving shocks when they propagate in ducts, is of great importance in a wide variety of applications, such as health, safety, and transportation. The objective of this research is to simulate the propagation of shock waves in ducts with roughness. The roughness is added in the form of grooves as in an existing experiment. Different shapes are considered in order to better understand the physics behind the evolution of the complex shock patterns resulting from diffraction, reflection and refraction of the primary moving shock. The contribution of grooves and duct shape on these phenomena and pressure ...


An Alternative Method Of Identification Of A Failed Engine In Twin-Engine Propeller Aircraft, Andrey Babin 2018 Embry-Riddle Aeronautical University

An Alternative Method Of Identification Of A Failed Engine In Twin-Engine Propeller Aircraft, Andrey Babin

Dissertations and Theses

Previous research has revealed that wrong identification of a failed engine during flight is not an uncommon event in an aircraft cockpit. A number of fatal accidents in the past, including the recent TransAsia Flight 235 accident, resulted from engine misidentification. Most accidents of this type happened on takeoff when pilot workload was at its highest level. This thesis consists of two research studies. For Research Study 1, a survey was created to gather opinions of airline pilots who operate twin-engine turboprop aircraft. Twenty-nine percent of respondents to the survey agreed with the statement that there could be a better ...


Development Of A Small Unmanned Aerial Vehicle Longitudinal Model For Future Flutter Testing, Said S. Hamada 2018 Embry-Riddle Aeronautical University

Development Of A Small Unmanned Aerial Vehicle Longitudinal Model For Future Flutter Testing, Said S. Hamada

Dissertations and Theses

This thesis presents the system identification of the longitudinal motion of a small unmanned aerial vehicle with flexible characteristics. The unmanned aerial vehicle of study is an off-the-shelf aircraft with limited knowledge about the dynamic model. The first task in obtaining a model for flutter testing is determining the rigid body model. Specifically, this thesis will focus in the development of the aircraft and obtaining the longitudinal rigid body model. This involves the assembly and configuration of the avionics and sensors, performing experiments to determine mass and inertia properties and using software tools for aerodynamic analysis to get preliminary values ...


Feasibility Study Of A Multi-Purpose Aircraft Concept With A Leading-Edge Cross-Flow Fan, Stanislav Karpuk 2018 Embry-Riddle Aeronautical University

Feasibility Study Of A Multi-Purpose Aircraft Concept With A Leading-Edge Cross-Flow Fan, Stanislav Karpuk

Dissertations and Theses

A wing-embedded Cross-Flow Fan (CFF) was first proposed as an active flow control (AFC) device nearly 40 years ago. The CFF can be employed as a propulsion device as well as a high-lift system. This thesis research focuses on investigating the use of CFF as a high-lift device for an Extremely Short Take-off and Landing (ESTOL) aircraft. The wing-embedded CFF performance analysis is mostly addressed from an aerodynamic perspective and focuses on using such AFC technology in the conceptual aircraft design process. In particular, the design trade study of an aircraft featuring CFF as a high-lift device applied to a ...


Experimental Investigation Of Enhanced Damage Resistant Fiber Metal Laminates, Cannelle Metang Tefoung 2018 Embry-Riddle Aeronautical University

Experimental Investigation Of Enhanced Damage Resistant Fiber Metal Laminates, Cannelle Metang Tefoung

Dissertations and Theses

Fiber metal laminates (FMLs) are hybrid composite structures made from fiber reinforced polymeric materials sandwiched between layers of thin metal alloy sheets. FMLs combine the advantages of metallic materials and fiber reinforced matrix systems. Some of these advantages include: lighter weight, enhanced impact tolerance, improved corrosion resistance, better fire resistance, longer fatigue life, greater tensile strength, easier repair ability and maintainability, etc. The most well-known commercially available FML is GLARE (Glass Laminate Aluminum Reinforced Epoxy), however there are ongoing issues, which include a very high fabrication cost compared to many competing material systems and substantial delamination upon impact and failure ...


Homography-Based State Estimation For Autonomous Exploration In Unknown Environments, Andres S. Chavez Armijos 2018 Embry-Riddle Aeronautical University

Homography-Based State Estimation For Autonomous Exploration In Unknown Environments, Andres S. Chavez Armijos

Dissertations and Theses

This thesis presents the development of vision-based state estimation algorithms to enable a quadcopter UAV to navigate and explore a previously unknown GPS denied environment. These state estimation algorithms are based on tracked Speeded-Up Robust Features (SURF) points and the homography relationship that relates the camera motion to the locations of tracked planar feature points in the image plane. An extended Kalman filter implementation is developed to perform sensor fusion using measurements from an onboard inertial measurement unit (accelerometers and rate gyros) with vision-based measurements derived from the homography relationship. Therefore, the measurement update in the filter requires the processing ...


Phase Field Study Of Surface-Induced Melting And Solidification From A Nanovoid: Effect Of Dimensionless Width Of Void Surface And Void Size, Anup Basak, Valery I. Levitas 2018 Iowa State University

Phase Field Study Of Surface-Induced Melting And Solidification From A Nanovoid: Effect Of Dimensionless Width Of Void Surface And Void Size, Anup Basak, Valery I. Levitas

Physics and Astronomy Publications

The size effect and the effects of a finite-width surface on barrierless transformations between the solid (S), surface melt (SM), and melt (M) from a spherical nanovoid are studied using a phase field approach. Melting (SM → M and S → M) from the nanovoid occurs at temperatures which are significantly greater than the solid-melt equilibrium temperature θe but well below the critical temperature for solid instability. The relationships between the SM and M temperatures and the ratio of the void surface width and width of the solid-melt interface, Δ⎯⎯⎯, are found for the nanovoids of different sizes. Below a critical ratio ...


Thrust Augmented Nozzle For A Hybrid Rocket With A Helical Fuel Port, Joel H. Marshall 2018 Utah State University

Thrust Augmented Nozzle For A Hybrid Rocket With A Helical Fuel Port, Joel H. Marshall

All Graduate Theses and Dissertations

A thrust augmented nozzle for hybrid rocket systems is investigated. The design lever-ages 3-D additive manufacturing to embed a helical fuel port into the thrust chamber of a hybrid rocket burning gaseous oxygen and ABS plastic as propellants. The helical port significantly increases how quickly the fuel burns, resulting in a fuel-rich exhaust exiting the nozzle. When a secondary gaseous oxygen flow is injected into the nozzle downstream of the throat, all of the remaining unburned fuel in the plume spontaneously ignites. This secondary reaction produces additional high pressure gases that are captured by the nozzle and significantly increases the ...


Active Permanent Magnet Attitude Control For Cubesats Using Mu-Metal Shielding, Maxwell Martin 2018 University of Arkansas, Fayetteville

Active Permanent Magnet Attitude Control For Cubesats Using Mu-Metal Shielding, Maxwell Martin

Mechanical Engineering Undergraduate Honors Theses

Cube-Satellites (CubeSats) are nanosatellites composed of cube shaped units, each nominally 10cm to a side and around 1kg in mass. Due to their inherent size and weight limitations, it is often impractical to use conventional attitude, or rotational, control methods such as thrusters on these small satellites. Several methods, including magnetorquer rods and small reaction wheels, are often used instead of traditional methods to work around the size and weight limitations. As a new alternative to these methods, a permanent magnet mounted on a rotatable shaft could be used to achieve attitude control. In much the same way that a ...


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