You searched for +publisher:"University of Kansas" +contributor:("Keshmiri, Shawn").
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University of Kansas
1.
Brown, Matthew Alan.
A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow.
Degree: MS, Aerospace Engineering, 2013, University of Kansas
URL: http://hdl.handle.net/1808/14195 
► The methods presented in this work are intended to provided an easy to understand and easy to apply method for determining the distributed aerodynamic loads…
(more)
▼ The methods presented in this work are intended to provided an easy to understand and easy to apply method for determining the distributed aerodynamic loads and aerodynamic characteristics of planforms of nearly arbitrary shape. Through application of the cranked wing approach, most planforms can be modeled including nearly all practical lifting surfaces with some notable exceptions. The methods are extremely accurate for elliptic wings and rectangular wings with some notable difficulty attributed to swept wings and wings with control surface deflection. A method for accounting for the shift in the locus of aerodynamic centers is also presented and applied to the lifting line theory to mitigate singularities inherent in its formulation. Comparisons to other numerical methods as well as theoretical equations and experimental data suggest that the method is reasonably accurate, but limited by some of its contributing theories. Its biggest benefit is its ability to estimate viscous effects which normally require more sophisticated models.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Aerodyanmic loads; Cranked wing; Wing aerodyanmics; Wing loads
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APA (6th Edition):
Brown, M. A. (2013). A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/14195
Chicago Manual of Style (16th Edition):
Brown, Matthew Alan. “A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow.” 2013. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/14195.
MLA Handbook (7th Edition):
Brown, Matthew Alan. “A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow.” 2013. Web. 18 Jan 2021.
Vancouver:
Brown MA. A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow. [Internet] [Masters thesis]. University of Kansas; 2013. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/14195.
Council of Science Editors:
Brown MA. A Computational Method for Determining Distributed Aerodynamic Loads on Planforms of Arbitrary Shape in Compressible Subsonic Flow. [Masters Thesis]. University of Kansas; 2013. Available from: http://hdl.handle.net/1808/14195
University of Kansas
2.
Lykins, Ryan.
Unsteady Aerodynamic and Dynamic Analysis of the Meridian UAS in a Rolling-Yawing Motion.
Degree: MS, Aerospace Engineering, 2014, University of Kansas
URL: http://hdl.handle.net/1808/14605
► The nonlinear and unsteady aerodynamic effects of operating the Meridian unmanned aerial system (UAS) in crosswinds and at high angular rates is investigated in this…
(more)
▼ The nonlinear and unsteady aerodynamic effects of operating the Meridian unmanned aerial system (UAS) in crosswinds and at high angular rates is investigated in this work. The Meridian UAS is a large autonomous aircraft, with a V-tail configuration, operated in Polar Regions for the purpose of remotely measuring ice sheet thickness. The inherent nonlinear coupling produced by the V-tail, along with the strong atmospheric disturbances, has made classical model identification methods inadequate for proper model development. As such, a powerful tool known as Fuzzy Logic Modeling (FLM) was implemented to generate time-dependent, nonlinear, and unsteady aerodynamic models using flight test data collected in Greenland in 2011. Prior to performing FLM, compatibility analysis is performed on the data, for the purpose of systematic bias removal and airflow angle estimation. As one of the advantages of FLM is the ability to model unsteady aerodynamics, the reduced frequency for both longitudinal and lateral-directional motions is determined from the unbiased data, using Theodorsen's theory of unsteadiness, which serves as an input parameter in modeling. These models have been used in this work to identify pilot induced oscillations, unsteady coupling motions, unsteady motion due to the slipstream and cross wind interaction, and destabilizing motions and orientations. This work also assesses the accuracy of preliminary aircraft dynamic models developed using engineering level software, and addresses the autopilot Extended Kalman Filter state estimations.
Advisors/Committee Members: Keshmiri, Shawn (advisor), Lan, Edward (cmtemember), Hale, Richard (cmtemember).
Subjects/Keywords: Aerospace engineering; Crosswind; Unmanned aerial system; Unsteady aerodynamics; V-tail
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APA (6th Edition):
Lykins, R. (2014). Unsteady Aerodynamic and Dynamic Analysis of the Meridian UAS in a Rolling-Yawing Motion. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/14605
Chicago Manual of Style (16th Edition):
Lykins, Ryan. “Unsteady Aerodynamic and Dynamic Analysis of the Meridian UAS in a Rolling-Yawing Motion.” 2014. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/14605.
MLA Handbook (7th Edition):
Lykins, Ryan. “Unsteady Aerodynamic and Dynamic Analysis of the Meridian UAS in a Rolling-Yawing Motion.” 2014. Web. 18 Jan 2021.
Vancouver:
Lykins R. Unsteady Aerodynamic and Dynamic Analysis of the Meridian UAS in a Rolling-Yawing Motion. [Internet] [Masters thesis]. University of Kansas; 2014. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/14605.
Council of Science Editors:
Lykins R. Unsteady Aerodynamic and Dynamic Analysis of the Meridian UAS in a Rolling-Yawing Motion. [Masters Thesis]. University of Kansas; 2014. Available from: http://hdl.handle.net/1808/14605
University of Kansas
3.
Homsrivaranon, Kanin.
Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/21970
► Today, modern wind turbine size has become larger than ever. The conventional airfoil near rotor hub cannot provide the structure integrity for the rotor blades.…
(more)
▼ Today, modern wind turbine size has become larger than ever. The conventional airfoil near rotor hub cannot provide the structure integrity for the rotor blades. Large diameter wind turbine required for extremely thick airfoil, such as the FX77-W-343 34.4% wind turbine dedicated airfoil. The exceptionally thick airfoil has an unfavorable characteristic, such as sharp stalling and stalling at low angle of attack. To prevent undesired behavior, the FX77-W-343 airfoil with co-flow jet active flow control is simulated in 2-D CFD using STAR-CCM+ to investigate the enhancement in performance. The simulation is done at low Reynolds number of 1,000,000 with injection and suction momentum coefficient of 0.05. The simulation presents promising performance increase of maximum lift coefficient by 190% and improves lift-to-drag ratio by 94%. While sharp stalling behavior cannot be solved with co-flow jet flow control, the operating margin of the extremely thick airfoil is increased by 130% by delaying the stall angle of attack of 8deg.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering
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APA (6th Edition):
Homsrivaranon, K. (2016). Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/21970
Chicago Manual of Style (16th Edition):
Homsrivaranon, Kanin. “Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil.” 2016. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/21970.
MLA Handbook (7th Edition):
Homsrivaranon, Kanin. “Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil.” 2016. Web. 18 Jan 2021.
Vancouver:
Homsrivaranon K. Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/21970.
Council of Science Editors:
Homsrivaranon K. Investigation of Active Flow Control on an Extremely Thick Wind Turbine Airfoil. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/21970
University of Kansas
4.
Lee, Adrian Kok Chiang.
Evaluation of Protruding Centerbody on the Novel Airdata Sensor.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/22341
► A novel airdata sensor was developed at the University of Kansas1. The Bio-Inspired probe was designed for high angles of attack and sideslip use, suitable…
(more)
▼ A novel airdata sensor was developed at the
University of Kansas1. The Bio-Inspired probe was designed for high angles of attack and sideslip use, suitable for Unmanned Aerial Vehicle (UAV) flight control system and other highly maneuverable aircraft applications. The probe displayed excellent speed measurement of up to angle of attack and sideslip of ±40°, compared to ±25° exhibited by a conventional pitot tube at the same accuracy. With the goal of evaluating the novel probe’s protruding centerbody and effects on angular sensitivity, two new sets of probe were developed, featuring elongated (L/D 1.5) and shortened (L/D 0.5) protruding centerbodies to gain deeper understanding of the Coanda effect on the blunt protruding centerbody featured on the Bio-inspired probe. The protruding centerbody uses the Coanda effect to turn air flow streamline and attach to the centerbody surface. The analysis included pressure and velocity measurement at high angle of attack wind tunnel tests and Computational Fluid Dynamic simulations on the new and original (L/D 1.0) prototypes. As expected, the elongated ellipsoid centerbody (L/D 1.5) probe exhibited an improved flow capture. Design improvements such as centerbody optimization and direct drag measurement are suggested to improve the novel probe capabilities. Further research will be concentrated on a flight testing on a UAV with the novel airdata sensor and a conventional Pitot-static tube.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Engineering; airdata sensor; Bio-Inspired; Coanda effect; flow capture; protruding centerbody
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APA (6th Edition):
Lee, A. K. C. (2016). Evaluation of Protruding Centerbody on the Novel Airdata Sensor. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/22341
Chicago Manual of Style (16th Edition):
Lee, Adrian Kok Chiang. “Evaluation of Protruding Centerbody on the Novel Airdata Sensor.” 2016. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/22341.
MLA Handbook (7th Edition):
Lee, Adrian Kok Chiang. “Evaluation of Protruding Centerbody on the Novel Airdata Sensor.” 2016. Web. 18 Jan 2021.
Vancouver:
Lee AKC. Evaluation of Protruding Centerbody on the Novel Airdata Sensor. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/22341.
Council of Science Editors:
Lee AKC. Evaluation of Protruding Centerbody on the Novel Airdata Sensor. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/22341
University of Kansas
5.
D'Silva, Adam.
Investigation on Entropy Signature of Objects.
Degree: MS, Aerospace Engineering, 2017, University of Kansas
URL: http://hdl.handle.net/1808/24146
► With the use of modern configuration and advanced stealth technologies, aircraft have the ability to minimize their signatures significantly. The three main signatures being infrared,…
(more)
▼ With the use of modern configuration and advanced stealth technologies, aircraft have the ability to minimize their signatures significantly. The three main signatures being infrared, radar, and noise. A new observable, not taken into consideration, is entropy trail. This is a new and exciting area of research, to detect an object in motion, based on its entropy trail. The objective is to investigate two objects, a sphere and wing, generate an entropy trail regardless of shape, size, or implemented low observable technologies. Literature review established that the sphere and wing had negligible IR, radar, and noise signatures. IR signature was 0.18% and 0.07% off ambient temperature, radar signature was −19.9 dBm2 and −10.6dBm2, and noise signature was negligible since the incoming flow was M ≤ 0.1. The entropy trail of a sphere and wing were investigated using the 2nd Law of Thermodynamics and Gibbs equation. The trails were determined with CFD analysis at non-dimensionalized distances, away from the trailing edge, of the models. Wind tunnel measurements validated CFD results by measuring total pressure at arbitrary positions in the wake. Temperature measurements were not considered since the process is adiabatic. The results were in agreement between CFD and wind tunnel expect for the wing at 16 degrees angle of attack. This was due to the presence of a vortex and separated flow, which is difficult to capture with pitot tubes.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Entropy Signature; Low Observable
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APA (6th Edition):
D'Silva, A. (2017). Investigation on Entropy Signature of Objects. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/24146
Chicago Manual of Style (16th Edition):
D'Silva, Adam. “Investigation on Entropy Signature of Objects.” 2017. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/24146.
MLA Handbook (7th Edition):
D'Silva, Adam. “Investigation on Entropy Signature of Objects.” 2017. Web. 18 Jan 2021.
Vancouver:
D'Silva A. Investigation on Entropy Signature of Objects. [Internet] [Masters thesis]. University of Kansas; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/24146.
Council of Science Editors:
D'Silva A. Investigation on Entropy Signature of Objects. [Masters Thesis]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/24146
University of Kansas
6.
Chandra, Yatish.
Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics.
Degree: MS, Aerospace Engineering, 2017, University of Kansas
URL: http://hdl.handle.net/1808/25935
► Unmanned Aerial Systems (UASs) are relatively affordable and immediately available compared to commercial aircraft. Hence, their aerodynamics and design accuracies are often based on extrapolating…
(more)
▼ Unmanned Aerial Systems (UASs) are relatively affordable and immediately available compared to commercial aircraft. Hence, their aerodynamics and design accuracies are often based on extrapolating from design standards and procedures widely used in the aerospace industry for commercial aircraft with most often, acceptable results. Engineering level software such as Advanced Aircraft Analysis (AAA) use general aviation aircraft data and later extrapolate them onto UASs for aerodynamic and flight dynamics modeling but are limited by their platform repository and relatively high Reynolds number evaluations. UASs however, are aircraft which fly at comparatively low speeds and low Reynolds number with close proximities between the components wherein such standards may not hold good. This thesis focuses on evaluating the accuracy and impact of such industry standards on the aerodynamics and flight dynamics of UASs. A DG808s UAS is chosen for the study which was previously modeled using the AAA software at The
University of
Kansas by the Flight Systems Team. Using the STAR-CCM+ code, performance data were compared and assessed with AAA. Aerodynamic simulations were carried out for two different configurations viz., aircraft with and without propeller slipstream effects. Data obtained for the non-powered simulations were found to be in good agreement with the AAA model. For the powered flight however, discrepancies between the AAA model and CFD data were observed with large values for the vertical tail side-force coefficient. A comparison with the system identification data from the flight tests was made to confirm and validate this vertical tail behavior with the help of rudder deflection inputs. A relationship between the propeller RPM and the aerodynamic model was established by simulating two different propeller speeds. Based on the STAR-CCM+ data and the resulting comparisons with AAA, updates necessary to the UAS aerodynamic and flight dynamics models currently used in the industry were discussed and concluded with a stress on dependency on higher fidelity methods such as Computational Fluid Dynamics.
Advisors/Committee Members: Taghavi, Ray (advisor), Keshmiri, Shawn (cmtemember), Farokhi, Saeed (cmtemember).
Subjects/Keywords: Aerospace engineering; Aerodynamics; CFD; DG808s; Downwash; Sidewash; UAS
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APA (6th Edition):
Chandra, Y. (2017). Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/25935
Chicago Manual of Style (16th Edition):
Chandra, Yatish. “Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics.” 2017. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/25935.
MLA Handbook (7th Edition):
Chandra, Yatish. “Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics.” 2017. Web. 18 Jan 2021.
Vancouver:
Chandra Y. Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics. [Internet] [Masters thesis]. University of Kansas; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/25935.
Council of Science Editors:
Chandra Y. Investigation of the Aerodynamic Performance of a DG808s UAS in Propeller Slipstream using Computational Fluid Dynamics. [Masters Thesis]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/25935
University of Kansas
7.
Wei, Zhenglun.
Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method.
Degree: PhD, Aerospace Engineering, 2014, University of Kansas
URL: http://hdl.handle.net/1808/19600
► Flight has fascinated humans for centuries. Human inventions such as missiles, aircraft , unmanned aerial vehicles (UAV), and micro air vehicle (MAV) are inspired by…
(more)
▼ Flight has fascinated humans for centuries. Human inventions such as missiles, aircraft , unmanned aerial vehicles (UAV), and micro air vehicle (MAV) are inspired by natural flying expertise. As natural flyers usually operate in a vortex-dominated environment, interactions between their wings and the vortices have significant influences on force generation and flying efficiency. Some interesting phenomena induced from such vortex-body interactions have gotten a lot of attention in the past few decades. A good example is that birds and insects are credited with extracting energy from ambient vortices. In a simpler form, bio-inspired airfoils with either passive or active flapping motions are found to have the potential to harvest energy from incoming vortices generated from an upstream object, i.e. a cylinder. The current study identified the interaction modes of the leading edge vortex (LEV) and trailing edge vortex (TEV) between the active flapping airfoil and the incoming vortices. The relation between the interaction modes and the energy extraction capacity of an active harvester is investigated guided by a potential theory. The interaction modes induced by a passive energy harvester always benefit the energy extraction efficiency. However, the dynamic response of the passive harvester was found to vary corresponding to the properties of the incoming vortical wake. A profound appreciation of energy extracting mechanisms can provide a solution for the energy consumption issue of MAV and UAV. However, difficulties are encountered in practical applications of energy harvesting on how to detect the locations of generated vortices and what the trajectory of the vortex downstream of the moving body is. Some observations are realized and the fluid dynamics of the phenomena is beyond the fundamentals described in the textbook. One well-known instance is the asymmetric wake formed downstream of a symmetric sinusoidal heaving airfoil. In this study, factors that influence the formation of the asymmetric wakes on both the near wake and far wake regions are demonstrated. Novel vortex models are developed to explore the vortex dynamic mechanisms of the asymmetric wake and its development from the near wake region to the far wake region. In order to analyze the flow fields for the bio-inspired problems, Computational Fluid Dynamics (CFD) provides powerful and convenient tools. The shape of bio-inspired wings/airfoils and their maneuvers are usually very complicated. In CFD, the immersed-boundary (IB) method is an advantageous approach to simulate such problems. In this study, an immersed-boundary method is implemented in a parallel fashion in order to speed up the computational rate.. A variety of numerical schemes have been applied to the IB method, including different spatial schemes and temporal schemes; their performances are investigated. In addition, the IB method has been successfully implemented with the fluid-structure interaction models for studying passive mobile objectives, i.e. the energy harvester. The possibility…
Advisors/Committee Members: Zheng, Zhongquan (advisor), Farokhi, Saeed (cmtemember), Huang, Weizhang (cmtemember), Keshmiri, Shawn (cmtemember), Taghavi, Ray (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering
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APA (6th Edition):
Wei, Z. (2014). Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/19600
Chicago Manual of Style (16th Edition):
Wei, Zhenglun. “Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method.” 2014. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/19600.
MLA Handbook (7th Edition):
Wei, Zhenglun. “Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method.” 2014. Web. 18 Jan 2021.
Vancouver:
Wei Z. Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method. [Internet] [Doctoral dissertation]. University of Kansas; 2014. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/19600.
Council of Science Editors:
Wei Z. Numerical and theoretical study of flapping airfoil aerodynamics using a parallelized immersed-boundary method. [Doctoral Dissertation]. University of Kansas; 2014. Available from: http://hdl.handle.net/1808/19600
University of Kansas
8.
Stastny, Thomas James.
Collision Avoidance for Fixed-Wing Unmanned Aerial Systems Using Morphing Potential Field Navigation with Robust and Predictive Control.
Degree: MS, Aerospace Engineering, 2014, University of Kansas
URL: http://hdl.handle.net/1808/19613
► The vast utility of unmanned aerial systems in wide-ranging applications, whether civil, militaristic, or academic, has accelerated the prospect of integration into civil airspace, and…
(more)
▼ The vast utility of unmanned aerial systems in wide-ranging applications, whether civil, militaristic, or academic, has accelerated the prospect of integration into civil airspace, and further, use in proximal collaborative operations and congested urban areas. For safety in autonomous operations of the kind, onboard navigation algorithms will require the ability to generate collision free paths in real-time. Guidance and robust control systems must maintain tight spatial and temporal tracking of these paths in the presence of environmental hazards, a twofold objective involving both sensors and control system development; here, the latter is targeted. This work proposes a combined real-time navigation, guidance, and robust control scheme for collision and obstacle avoidance in the particular case of fixed-wing unmanned aerial systems operating in demanding proximal and congested settings. Classical artificial potential field navigational approaches are uniquely reformulated, morphing the fields by consideration of six-degrees-of-freedom dynamic characteristics and constraints of high speed and high inertia fixed-wing aircraft. Time-varying waypoints are planned in a predictive horizon and subsequently embedded into an integrated guidance and nonlinear model predictive controller. Nonlinear six-degrees-of-freedom simulation of a suite of vehicle-to-vehicle and obstacle avoidance scenarios in unstructured environments demonstrate robust, real-time, and efficient avoidance capabilities of the developed algorithms.
Advisors/Committee Members: Keshmiri, Shawn S (advisor), Downing, David R (cmtemember), Hale, Richard D (cmtemember), Ewing, Mark S (cmtemember).
Subjects/Keywords: Aerospace engineering; Artificial Potential Field; Collision Avoidance; Path Planning; Real-time; Robust Control; UAS
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APA (6th Edition):
Stastny, T. J. (2014). Collision Avoidance for Fixed-Wing Unmanned Aerial Systems Using Morphing Potential Field Navigation with Robust and Predictive Control. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/19613
Chicago Manual of Style (16th Edition):
Stastny, Thomas James. “Collision Avoidance for Fixed-Wing Unmanned Aerial Systems Using Morphing Potential Field Navigation with Robust and Predictive Control.” 2014. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/19613.
MLA Handbook (7th Edition):
Stastny, Thomas James. “Collision Avoidance for Fixed-Wing Unmanned Aerial Systems Using Morphing Potential Field Navigation with Robust and Predictive Control.” 2014. Web. 18 Jan 2021.
Vancouver:
Stastny TJ. Collision Avoidance for Fixed-Wing Unmanned Aerial Systems Using Morphing Potential Field Navigation with Robust and Predictive Control. [Internet] [Masters thesis]. University of Kansas; 2014. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/19613.
Council of Science Editors:
Stastny TJ. Collision Avoidance for Fixed-Wing Unmanned Aerial Systems Using Morphing Potential Field Navigation with Robust and Predictive Control. [Masters Thesis]. University of Kansas; 2014. Available from: http://hdl.handle.net/1808/19613
University of Kansas
9.
Al Aziz, Masud.
Navigation for UAVs using Signals of Opportunity.
Degree: PhD, Electrical Engineering & Computer Science, 2015, University of Kansas
URL: http://hdl.handle.net/1808/20929
► The reliance of Unmanned Aerial Vehicles (UAVs) on Global Navigation Satellite System (GNSS) for autonomous operation represents a significant vulnerability to their reliable and secure…
(more)
▼ The reliance of Unmanned Aerial Vehicles (UAVs) on Global Navigation Satellite System (GNSS) for autonomous operation represents a significant vulnerability to their reliable and secure operation due to signal interference, both incidental (e.g. terrain shadowing, ionospheric scintillation) and malicious (e.g. jamming, spoofing). An accurate and reliable alternative UAV navigation system is proposed that exploits Signals of Opportunity (SOP) thus offering superior signal strength and spatial diversity compared to satellite signals. Given prior knowledge of the transmitter's position and signal characteristics, the proposed technique utilizes triangulation to estimate the receiver's position. Dual antenna interferometry provides the received signals' Angle of Arrival (AoA) required for triangulation. Reliance on precise knowledge of the antenna system's orientation is removed by combining AoAs from different transmitters to obtain a differential Angles of Arrival (dAoAs). Analysis, simulation, and ground-based experimental techniques are used to characterize system performance; a path to miniaturized system integration is also presented. Results from these ground-based experiments show that when the received signal-to-noise ratio (SNR) is above about 45 dB (typically in within 30 km of the transmitters), the proposed method estimates the receiver's position uncertainty range from less than 20 m to about 60 m with an update rate of 10 Hz.
Advisors/Committee Members: Allen, Christopher (advisor), Blunt, Shannon (cmtemember), Hui, Rongqing (cmtemember), Yun, Heechul (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Electrical engineering
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APA (6th Edition):
Al Aziz, M. (2015). Navigation for UAVs using Signals of Opportunity. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/20929
Chicago Manual of Style (16th Edition):
Al Aziz, Masud. “Navigation for UAVs using Signals of Opportunity.” 2015. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/20929.
MLA Handbook (7th Edition):
Al Aziz, Masud. “Navigation for UAVs using Signals of Opportunity.” 2015. Web. 18 Jan 2021.
Vancouver:
Al Aziz M. Navigation for UAVs using Signals of Opportunity. [Internet] [Doctoral dissertation]. University of Kansas; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/20929.
Council of Science Editors:
Al Aziz M. Navigation for UAVs using Signals of Opportunity. [Doctoral Dissertation]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/20929
University of Kansas
10.
Bowman, Alec Davis.
Gain-Scheduled H-Infinity Control and Analysis of a Nonlinear Generic Hypersonic Vehicle.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/22339
► The concept of hypersonic flight has been around for many years. In recent years, emerging technologies and market forces have renewed latent interest in this…
(more)
▼ The concept of hypersonic flight has been around for many years. In recent years, emerging technologies and market forces have renewed latent interest in this challenging field. With many private and government institutions driving new innovations, these concepts are becoming reality. New research is needed to facilitate future innovation and deployment. The complex dynamic behaviors within the hypersonic flight envelope must be studied for designers to either mitigate or compensate for their effects on future vehicles. Control techniques must be adapted to suit the unstable and highly nonlinear dynamics of such systems. This work has two goals: to explore the dynamic characteristics of hypersonic flight and to control such a vehicle in the face of non-linearly changing dynamics. A nonlinear, 6 degree of freedom dynamic model of a Generic Hypersonic Vehicle is developed. The model integrates changing mass, moments of inertia, and center of gravity as a function of fuel burn. A bank of spline interpolation tables generates aerodynamic coefficients dependent on speed, angle of attack, and control surface deflections for the entire flight envelope. The nonlinear model of the full flight envelope is then reduced to a series of linear models to represent the aircraft trimmed under straight and level flight conditions over the range of Mach numbers, Mach 2 to 23. The changing Longitudinal and Lateral dynamics of the linearized system are analyzed as a function of Mach number using standard linear techniques to show the changing vehicle characteristics. A spline-based gain-scheduled, H-infinity controller is also designed for a subset of the linear systems. The controller stabilizes the system between Mach 4.9 and 7.1, with aircraft weight ranging from 160,000 to 230,000 pounds and from 68,000 to 92,000 feet altitude. The controller maintains system stability while commanded to change both Mach number and altitude within the gain-scheduled envelope. Additionally, the controller’s performance is assessed in the presence of low frequency disturbances.
Advisors/Committee Members: Keshmiri, Shawn S (advisor), Ewing, Mark S (cmtemember), Hale, Richard D (cmtemember).
Subjects/Keywords: Aerospace engineering; aircraft dynamics; control theory; gain scheduling; h-infinity control; Hypersonic aircraft; robust control
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APA (6th Edition):
Bowman, A. D. (2016). Gain-Scheduled H-Infinity Control and Analysis of a Nonlinear Generic Hypersonic Vehicle. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/22339
Chicago Manual of Style (16th Edition):
Bowman, Alec Davis. “Gain-Scheduled H-Infinity Control and Analysis of a Nonlinear Generic Hypersonic Vehicle.” 2016. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/22339.
MLA Handbook (7th Edition):
Bowman, Alec Davis. “Gain-Scheduled H-Infinity Control and Analysis of a Nonlinear Generic Hypersonic Vehicle.” 2016. Web. 18 Jan 2021.
Vancouver:
Bowman AD. Gain-Scheduled H-Infinity Control and Analysis of a Nonlinear Generic Hypersonic Vehicle. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/22339.
Council of Science Editors:
Bowman AD. Gain-Scheduled H-Infinity Control and Analysis of a Nonlinear Generic Hypersonic Vehicle. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/22339
University of Kansas
11.
Raina, Amool A.
IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS.
Degree: PhD, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/23513
► This dissertation is aimed at understanding the impact on performance, loads and cost using integral vortex generators on wind turbine blade designs. In order to…
(more)
▼ This dissertation is aimed at understanding the impact on performance, loads and cost using integral vortex generators on wind turbine blade designs. In order to investigate the possibility of this new design space, an optimization analysis is carried out. Three configurations are designed as a part of this dissertation. The current phase of work consists of creating a baseline blade that spans 56m in length. In order to determine the effectiveness of vortex generators on airfoils used on the 56m blade design, a verification and validation study of CFD tools is carried out. For this exercise, the LS(1)-0417MOD airfoil is used. STAR CCM+ software is used for performing the CFD analysis on the clean and vortex generator configurations of the LS(1)-0417MOD airfoil. Satisfactory results are obtained from the CFD analysis. A CFD analysis of a 47% thick airfoil is performed as well. This data has been used in the design of the 56m blade. Further, finite span airfoils incorporating vortex generators for the FB47 and NACA63621 airfoils are analyzed. This data is then used to evaluate the improvement of aerodynamic performance of the add-on 56m blade configuration. Vortex generators are incorporated in the post design phase of the clean 56m blade design and the improvement in performance in recorded. It is observed that a 0.4% improvement in AEP along with a 1.2% increase in loads and 2.13% increase in cost of energy is seen. Thereafter, the optimization and design of the 56m blade with integral vortex generators is carried out. Finally a full blade design of the 56m blade with integral vortex generators is carried out and the key performance metrics are recorded. A 1.7% increase in aerodynamic performance is recorded for the integral vortex generator case. This increase in performance also results in a 15.3% increase in blade root bending moment. However, a reduction in the total cost of energy is obtained as compared to the baseline blade design.
Advisors/Committee Members: Farokhi, Saeed (advisor), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember), Zheng, Zhongquan (cmtemember), Medina, Mario (cmtemember).
Subjects/Keywords: Aerospace engineering; Vortex generators; Wind Energy; Wind Turbines
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APA (6th Edition):
Raina, A. A. (2016). IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/23513
Chicago Manual of Style (16th Edition):
Raina, Amool A. “IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS.” 2016. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/23513.
MLA Handbook (7th Edition):
Raina, Amool A. “IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS.” 2016. Web. 18 Jan 2021.
Vancouver:
Raina AA. IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS. [Internet] [Doctoral dissertation]. University of Kansas; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/23513.
Council of Science Editors:
Raina AA. IMPACT ON WIND TURBINE BLADE DESIGN AND AERODYNAMIC PERFORMANCE USING INTEGRAL VORTEX GENERATORS. [Doctoral Dissertation]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/23513
12.
Underwood, Sean Christopher.
Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade.
Degree: PhD, Aerospace Engineering, 2018, University of Kansas
URL: http://hdl.handle.net/1808/27605
► The service life of gas turbine engine turbine blades depends on the blade’s material, service temperature and total stress. In high-performance gas turbines, film cooling…
(more)
▼ The service life of gas turbine engine turbine blades depends on the blade’s material, service temperature and total stress. In high-performance gas turbines, film cooling is widely used to reduce the blade service temperature. Often impingement cooling is also employed to target the stagnation point heat transfer for internally-cooled gas turbine blades. A novel thermal wind tunnel was designed to study the combined effect of the impingement and film cooling on blunt airfoils. The hot exhaust plume of a micro-jet is used as the source of high-temperature gas flow in the thermal wind tunnel. An ejector nozzle was designed and integrated with the hot jet to provide a thermally controlled test section environment in the research facility. Measurements of freestream parameters such as gas speed, turbulence intensity and gas temperature were made. An airfoil that utilizes leading-edge (internal) impingement as well as film cooling holes on its suction surface was designed and fabricated. A cooling sleeve is used inside the airfoil to guide the impingement jets on the leading edge and to supply the coolant to the film holes. The surface temperature distribution is measured by an array of eight thermocouples flush-mounted on the airfoil surface downstream of the film holes. The initial ranges of blowing parameters (Mb) investigated were between 5 and 6. Numerical simulation using a commercially available Reynolds-Averaged Navier-Stokes (RANS) software was used and validated by the experimental measurements. The numerical simulations for the airfoil consisted of two thermal wall boundary conditions, the adiabatic and conjugate heat transfer (CHT) models. The adiabatic model focuses on the effect of film cooling on an adiabatic wall. The conjugate heat transfer model represents the solid and fluid heat transfer exchange, conduction and convection. Verification and validation was completed to ensure accurate aerothermodynamic simulations. The experimental and numerical data showed a close comparison for the suction surface temperatures and cooling effectiveness. A broader range of characteristic parameters (blowing parameter, turbulence intensity (Tu) and density ratio) were studied to show their impact on film cooling effectiveness parameter. The effects from the blowing parameter are reported for different Mb of 0.53 to 5.95 with two turbulent intensities, 5% and 20%. The adiabatic film effectiveness parameter showed two unique trends: low Mb with low Tu or high Mb with high Tu both exhibited improved film cooling effectiveness. Jet detachment is also detected at Mb ~ 1.5 for the current film cooling set up. The study of turbulence intensity effects was completed in the range of 5% to 25 % for two density ratios of 1.65 and 1.99. The turbulence intensity study showed that higher Tu caused the adiabatic film effectiveness to decrease by an average 18%. The density ratio (DR) in the film cooling is studied to explore the real turbine environment. The velocity ratio and turbulence intensity is held at a constant of 0.64 and…
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (advisor), Wu, Huixuan (cmtemember), Keshmiri, Shawn (cmtemember), Medina, Mario (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering; Aerothermodynamics; Film Cooling; Gas Turbine; Impingement Cooling; Propulsion; Turbine Blade Cooling
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Export
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APA (6th Edition):
Underwood, S. C. (2018). Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/27605
Chicago Manual of Style (16th Edition):
Underwood, Sean Christopher. “Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade.” 2018. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/27605.
MLA Handbook (7th Edition):
Underwood, Sean Christopher. “Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade.” 2018. Web. 18 Jan 2021.
Vancouver:
Underwood SC. Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade. [Internet] [Doctoral dissertation]. University of Kansas; 2018. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/27605.
Council of Science Editors:
Underwood SC. Aerothermodynamics of Impingement and Film Cooling in a Gas Turbine Blade. [Doctoral Dissertation]. University of Kansas; 2018. Available from: http://hdl.handle.net/1808/27605
University of Kansas
13.
Smith, Leslie Ann.
The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber.
Degree: PhD, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19415
► One of the greatest problems that scramjet research faces is fuel air mixing. The residence time for a scramjet engine, or the time it takes…
(more)
▼ One of the greatest problems that scramjet research faces is fuel air mixing. The residence time for a scramjet engine, or the time it takes for a volume of air to completely pass through the engine, is on the order of 0.1 ms. In that extremely short period of time fuel must be injected and fully mirco-mixed at stoichiometric ratios with the combustion chamber airflow. The fuel-air mixture must then be combusted and expanded through the nozzle to produce thrust. The goal of this research is to develop a new more efficient method of fuel air mixing within a scramjet combustion chamber. A possible way to speed up the mixing process of parallel injection without incurring the total pressure losses that would occur in normal injection is to inject the fuel from the rear side of a backward facing step. Backward facing steps in supersonic flow produce a Prandtl-Meyer expansion fan followed by a shear layer. The instabilities in this shear layer have dominant resonant frequencies. It is believed that if fuel is injected in pulses that impinge on the shear layer at these dominant resonant frequencies that the shear layer will resonate. When the shear layer resonates the vortices that form in the shear layer will grow in magnitude, thus mixing the injected fuel with the air. To test this hypothesis a new test section was designed and built that features a one inch step under which an injector can be housed. This new test section was installed in the supersonic facility at the
University of
Kansas. Two injectors were also designed that each feature a face plate, one with eight injection ports arranged in a ring and one with 5 injection ports. Between the face plate and a back plate there is a cavity that houses a rotating valve that is powered by a pneumatic motor. Five valves were built: one with 8 teeth, one with 16 teeth, one with 5 teeth that are the same size as the gaps between the teeth, one with 5 teeth where the teeth are 50% larger than the gaps, and one with 5 teeth where the teeth are 50% smaller than the gaps. The 8 tooth valve and 16 tooth valve where used with the 8 port injector face plate. The 5 tooth valves were used with the 5 port injector face plate. As the valve rotates the teeth block and unblock the injection ports injecting carbon dioxide gas into the test section. The 8 port injector was tested over a range of frequencies from 1.6 kHz to 10.0 kHz. The 5 port injector was tested for each valve over a range of frequencies from 1.0 kHz to 4.0 kHz. Static pressure data was taken along the upper and lower walls of the test section by means of an array of pressure sensors. The pressure data from the test section was compared to results generated using a three dimensional CFD simulation of the test section. Overall the pressure data on the lower wall agreed reasonably well with the CFD simulation. The vorticity and turbulence contours generated by the STAR-CCM+ simulation suggest that as a pulse is injected into the test section from the step it causes the shear layer to curve outward near the point of…
Advisors/Committee Members: Farokhi, Saeed (advisor), Barrett, Ron (cmtemember), Taghavi, Ray (cmtemember), Yimer, Bedru (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Injector; Micro-mixing; Pulsed Injection; Scramjet; Shear Layer
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APA ·
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MLA ·
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CSE |
Export
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APA (6th Edition):
Smith, L. A. (2015). The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/19415
Chicago Manual of Style (16th Edition):
Smith, Leslie Ann. “The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber.” 2015. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/19415.
MLA Handbook (7th Edition):
Smith, Leslie Ann. “The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber.” 2015. Web. 18 Jan 2021.
Vancouver:
Smith LA. The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber. [Internet] [Doctoral dissertation]. University of Kansas; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/19415.
Council of Science Editors:
Smith LA. The Effect of Pulsed Injection on Shear Layer Dynamics in a Scramjet Combustion Chamber. [Doctoral Dissertation]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19415
University of Kansas
14.
Kim, A Ram.
Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification.
Degree: PhD, Aerospace Engineering, 2018, University of Kansas
URL: http://hdl.handle.net/1808/27816
► Following the exponential growth in the usage of unmanned aerial systems (UASs) across the Aerospace Industry, more intelligent and robust guidance, navigation, and control algorithms…
(more)
▼ Following the exponential growth in the usage of unmanned aerial systems (UASs) across the Aerospace Industry, more intelligent and robust guidance, navigation, and control algorithms are vital to cope with increasing levels of mission complexity. Additionally, many unmanned aerial operations require large payloads and long endurance such as extended reconnaissance, large-scale search and rescue and fine resolution terrain mapping. However, the stringent payload of a single agent or small UASs reduces their overall practicality and effectiveness. My research aims to address these inherent limitations of small UASs with a swarm by holding the required formation in order to distribute tasks and payload among multiple UASs. The goal of this research is to overcome the challenges of operating multi-agent systems by developing phasic navigation and guidance algorithms. Aircraft dynamics and their interactions with surrounding agents are highly nonlinear, which makes autonomous formation flight very sensitive to aircraft initial conditions. The phasic navigation algorithms are proposed and consist of hybrid mathematical approaches: Frenet-Serret curvature control, Hungarian algorithm and moving mesh methods. At the first phase, the curvature control allieviates the sensitivity to initial conditions of multi-agent UASs in unstructured environments by matching agents’ heading angle to the united direction. A variation of Hungarian algorithm is implemented with a moving virtual terminal to assign each agent to the formation position. In the second phase of navigation, the moving mesh methods are applied for holding the formation by defining the outer agents’ position for the boundary condition. The significance of the moving mesh methods is a scalability and a inherent intercollision avoidance. Due to the profound difference between the longitudinal and lateral-directional motion of a fixed-wing aircraft, a multi-scale moving point guidance algorithm has been designed to create the separate virtual reference points in the longitudinal and lateral-direction planes for the first time. This method has been shown to greatly reduce tracking oscillations and improve the overall tracking quality and coherency of the formation. Monte Carlo simulations are performed to ensure the stability and robustness of implementing proposed algorithms through an essentially exhaustive search. A broad range of random initial conditions have been used to validate the effectiveness of guidance, navigation, and control algorithms. Another unique contribution of this work is the validation and verification of proposed algorithms by the hardware-in-the-loop testbed and the numerous flight tests. The hardware-in-the-loop testbed is designed to test the avionics and communication before the flight test by simulating onboard 6-degrees of freedom nonlinear equations of motion. Over one hundred flight tests have been conducted using three distinct aircraft platforms between 2016 and 2018 to validate the fundamental building blocks of this architecture. In…
Advisors/Committee Members: Keshmiri, Shawn (advisor), Ewing, Mark (cmtemember), Hale, Richard (cmtemember), Farokhi, Saeed (cmtemember), Huang, Weizheng (cmtemember).
Subjects/Keywords: Aerospace engineering; Guidance; Multi-agent; Navigation; Validation; Verification
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APA (6th Edition):
Kim, A. R. (2018). Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/27816
Chicago Manual of Style (16th Edition):
Kim, A Ram. “Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification.” 2018. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/27816.
MLA Handbook (7th Edition):
Kim, A Ram. “Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification.” 2018. Web. 18 Jan 2021.
Vancouver:
Kim AR. Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification. [Internet] [Doctoral dissertation]. University of Kansas; 2018. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/27816.
Council of Science Editors:
Kim AR. Intelligent Guidance, Navigation and Control of Multi-Agent UASs with Validation and Verification. [Doctoral Dissertation]. University of Kansas; 2018. Available from: http://hdl.handle.net/1808/27816
University of Kansas
15.
Yu, Yufei.
An Adaptive Moving Mesh Finite Element Method and Its Application to Mathematical Models from Physical Sciences and Image Processing.
Degree: PhD, Mathematics, 2019, University of Kansas
URL: http://hdl.handle.net/1808/30071
► Moving sharp fronts are an important feature of many mathematical models from physical sciences and cause challenges in numerical computation. In order to obtain accurate…
(more)
▼ Moving sharp fronts are an important feature of many mathematical models from physical sciences and cause challenges in numerical computation. In order to obtain accurate solutions, a high resolution of mesh is necessary, which results in high computational cost if a fixed mesh is used. As a solution to this issue, an adaptive mesh method, which is called the moving mesh partial differential equation (MMPDE) method, is described in this work. The MMPDE method has the advantage of adaptively relocating the mesh points to increase the densities around sharp layers of the solutions, without increasing the mesh size. Moreover, this strategy can generate a nonsingular mesh even on non-convex and non-simply connected domains, given that the initial mesh is nonsingular. The focus of this thesis is on the application of the MMPDE method to mathematical models from physical sciences and image segmentation. In particular, this thesis includes the selection of the regularization parameter for the Ambrosio-Tortorelli functional, a simulation of the contact sets in the evolution of the micro-electro mechanical systems, and a numerical study of the flux selectivity in the Poisson-Nernst-Planck model. Sharp interfaces take place in all these three models, bringing interesting features and rich phenomena to study.
Advisors/Committee Members: Huang, Weizhang (advisor), Huang, Weizhang (cmtemember), Keshmiri, Shawn (cmtemember), Liu, Weishi (cmtemember), Tu, Xuemin (cmtemember), Van Vleck, Erik (cmtemember).
Subjects/Keywords: Applied mathematics
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APA ·
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Export
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Manager
APA (6th Edition):
Yu, Y. (2019). An Adaptive Moving Mesh Finite Element Method and Its Application to Mathematical Models from Physical Sciences and Image Processing. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/30071
Chicago Manual of Style (16th Edition):
Yu, Yufei. “An Adaptive Moving Mesh Finite Element Method and Its Application to Mathematical Models from Physical Sciences and Image Processing.” 2019. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/30071.
MLA Handbook (7th Edition):
Yu, Yufei. “An Adaptive Moving Mesh Finite Element Method and Its Application to Mathematical Models from Physical Sciences and Image Processing.” 2019. Web. 18 Jan 2021.
Vancouver:
Yu Y. An Adaptive Moving Mesh Finite Element Method and Its Application to Mathematical Models from Physical Sciences and Image Processing. [Internet] [Doctoral dissertation]. University of Kansas; 2019. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/30071.
Council of Science Editors:
Yu Y. An Adaptive Moving Mesh Finite Element Method and Its Application to Mathematical Models from Physical Sciences and Image Processing. [Doctoral Dissertation]. University of Kansas; 2019. Available from: http://hdl.handle.net/1808/30071
16.
Smith, Nathan Allen.
Optimal Lateral Guidance for Automatic Landing of a High Altitude Long Endurance Unmanned Aerial System with Crosswind Rejection.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/22354
► Unmanned aerial systems will be the dominant force in the aviation industry. Among these aircraft the use of high altitude long endurance unmanned aerial systems…
(more)
▼ Unmanned aerial systems will be the dominant force in the aviation industry. Among these aircraft the use of high altitude long endurance unmanned aerial systems has increased dramatically. Based on the geometry of these types of aircraft the possible changing weather conditions during long flights poses many problems. These difficulties are compounded by the push towards fully autonomous systems. Large wingspan and, typically, small in-line landing gear make a landing in crosswind exceedingly difficult. This study uses a modified gain scheduling technique for optimizing the landing attitude for a generic vehicle based on geometry and crosswind speed. This is performed by directly utilizing the crosswind estimation to calculate a desired crab and roll angle that gives the lowest risk attitude for landing. An extended Kalman filter is developed that estimates the aircraft states as well as the 3D wind component acting on the aircraft. The aircraft used in this analysis is the DG808S, a large wingspan lightweight electric glider. The aircraft is modelled using Advanced Aircraft Analysis software and a six degree of freedom nonlinear simulation is implemented for testing. The controller used is a nonlinear model predictive controller. The simulations show that the extended Kalman filter is capable of estimating the crosswind and can therefore be used in the full aircraft simulation. Different crosswind settings are used which include both constant crosswind and gust conditions. Crosswind landing capabilities are increased by 35%. Deviation from the desired path in the cruise phase is reduced by up to 68% and time to path convergence is reduced by up to 53%.
Advisors/Committee Members: Keshmiri, Shawn (advisor), Keshmiri, Shawn (cmtemember), Ewing, Mark (cmtemember), Huang, Weizhang (cmtemember).
Subjects/Keywords: Aerospace engineering; Crosswind; Guidance; High Altitude Long Endurance; Unmanned Aerial System
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APA ·
Chicago ·
MLA ·
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APA (6th Edition):
Smith, N. A. (2016). Optimal Lateral Guidance for Automatic Landing of a High Altitude Long Endurance Unmanned Aerial System with Crosswind Rejection. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/22354
Chicago Manual of Style (16th Edition):
Smith, Nathan Allen. “Optimal Lateral Guidance for Automatic Landing of a High Altitude Long Endurance Unmanned Aerial System with Crosswind Rejection.” 2016. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/22354.
MLA Handbook (7th Edition):
Smith, Nathan Allen. “Optimal Lateral Guidance for Automatic Landing of a High Altitude Long Endurance Unmanned Aerial System with Crosswind Rejection.” 2016. Web. 18 Jan 2021.
Vancouver:
Smith NA. Optimal Lateral Guidance for Automatic Landing of a High Altitude Long Endurance Unmanned Aerial System with Crosswind Rejection. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/22354.
Council of Science Editors:
Smith NA. Optimal Lateral Guidance for Automatic Landing of a High Altitude Long Endurance Unmanned Aerial System with Crosswind Rejection. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/22354
17.
Benyamen, Hady.
Stability and Control Derivatives Identification for an Unmanned Aerial Vehicle with Low Cost Sensors Using an Extended Kalman Filter Algorithm.
Degree: MS, Aerospace Engineering, 2019, University of Kansas
URL: http://hdl.handle.net/1808/29631
► Unmanned aerial systems (UASs) tend to be autonomous vehicles. Thus, they require control algorithms. More advanced control algorithms can be developed when high quality UAS…
(more)
▼ Unmanned aerial systems (UASs) tend to be autonomous vehicles. Thus, they require control algorithms. More advanced control algorithms can be developed when high quality UAS dynamic models are available. It is common to develop dynamic models for UAS using low fidelity theoretical methods. In this thesis, a higher fidelity approach which has been used for manned aircraft over the past 40-50 years is applied to the SkyHunter UAS. That approach is system identification. In this approach, the aircraft dynamic model is developed based on flight data. This thesis focuses particularly on identifying the longitudinal stability and control derivatives of the UAS. Such derivatives are important in developing UAS dynamic models. An extended Kalman filter (EKF) algorithm was used to identify the derivatives. The algorithm is appealing since it can potentially allow online system identification. The SkyHunter analyzed in this thesis weighs about 10 lb. (4.5 kg) and its wing span is about 82 in (2 m.) Like many UASs, the SkyHunter uses relatively low-cost sensors. Therefore, the data contains high noise levels. Several flight portions from three different flights were analyzed and the results are presented. These flight portions were selected carefully based on criteria that make the flight data more suitable for system identification. The identified derivatives showed reasonable results in several instances. However, a large degree of variation was observed when comparing derivatives identified from the different flight portions. The inconsistency is caused by unsteady aerodynamics, sensor noise, inability of the EKF to capture aircraft dynamics due to the use of simplified equations of motion, along with other reasons discussed in the thesis. The unsteady aerodynamics were investigated through: (A) Calculation of reduced frequency and (B) Measuring the effect of the propeller on empennage aerodynamics. This is relevant since the propeller is directly in front of the empennage.
Advisors/Committee Members: Keshmiri, Shawn (advisor), Taghavi, Ray (cmtemember), Huang, Weizhang (cmtemember).
Subjects/Keywords: Aerospace engineering; Mechanical engineering; Aircraft System Identification; Extended Kalman Filter; Flight Dynamics; Stability and Control Derivatives; UAV; Unmanned Aerial Vehicle
…CFD results obtained from another UAS at the University of Kansas [18]. This… …of Kansas Flight
Systems Team owns several SkyHunter aircraft that it uses for research… …the SkyHunter
UAS. An image of the UAS is presented in the following figure. The University…
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APA (6th Edition):
Benyamen, H. (2019). Stability and Control Derivatives Identification for an Unmanned Aerial Vehicle with Low Cost Sensors Using an Extended Kalman Filter Algorithm. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/29631
Chicago Manual of Style (16th Edition):
Benyamen, Hady. “Stability and Control Derivatives Identification for an Unmanned Aerial Vehicle with Low Cost Sensors Using an Extended Kalman Filter Algorithm.” 2019. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/29631.
MLA Handbook (7th Edition):
Benyamen, Hady. “Stability and Control Derivatives Identification for an Unmanned Aerial Vehicle with Low Cost Sensors Using an Extended Kalman Filter Algorithm.” 2019. Web. 18 Jan 2021.
Vancouver:
Benyamen H. Stability and Control Derivatives Identification for an Unmanned Aerial Vehicle with Low Cost Sensors Using an Extended Kalman Filter Algorithm. [Internet] [Masters thesis]. University of Kansas; 2019. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/29631.
Council of Science Editors:
Benyamen H. Stability and Control Derivatives Identification for an Unmanned Aerial Vehicle with Low Cost Sensors Using an Extended Kalman Filter Algorithm. [Masters Thesis]. University of Kansas; 2019. Available from: http://hdl.handle.net/1808/29631
18.
Mullick, Sunayan.
IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS.
Degree: MS, Aerospace Engineering, 2017, University of Kansas
URL: http://hdl.handle.net/1808/25896
► A major contributor to the overall noise of an aircraft is jet noise – the noise generated by the gases exiting the exhaust nozzle of…
(more)
▼ A major
contributor to the overall noise of an aircraft is jet noise – the noise generated by the gases exiting the exhaust nozzle of a jet engine. One approach to mitigate jet noise is through the implementation of chevron nozzles. In the present context, first, a baseline axisymmetric separate-flow nozzle, termed the 3BB model, with an external plug having a bypass ratio of 5 is analyzed. The specifications of this nozzle are taken from an acoustic study carried out at the NASA John H. Glenn Research Center. Then, various chevron configurations are added to the core and fan nozzles to produce three chevron nozzles. Of these, two are presented as modified versions of the conventional chevron nozzle and form the essence of this work. The third chevron nozzle represents the conventional chevron nozzle in use today. For all the nozzles considered in this study, the flow conditions used represent the takeoff environment of a contemporary subsonic aircraft. The fan nozzle total pressure is set to 1.8 atm while the core nozzle total pressure is 1.65 atm. The total temperature inside the fan nozzle is set to 333.3 K while the core nozzle has a total temperature of 833.3 K. The freestream conditions are given as: static pressure = 0.98 atm, total pressure = 1.04 atm, total temperature = 298.8 K and Mach number = 0.28. For the three chevron nozzles, the core and fan nozzles have 12 chevrons each. Each chevron extends over a sector of 30 degrees of the circumference. To carry out the study presented herein, first, computer-aided design (CAD) models of the four nozzles are created. These models are then used to carry out computational fluid dynamics (CFD) simulations with the conditions stated above. The CFD simulations are performed on STAR-CCM+. The results of the simulations carried out for the baseline nozzle are compared with existing experimental and numerical data to validate the use of STAR-CCM+ as a tool for studying jet flows. Once this step is complete, numerical simulations are carried out for the three chevron nozzles. The results from these are compared with those obtained for the baseline nozzle. The turbulent kinetic energy (TKE) and the mean axial velocity are the two main parameters that represent mixing enhancement and are focused on in this work. Since the TKE levels for a given nozzle are directly linked to the jet noise generated, the TKE is an important indication of the jet noise produced by a given nozzle. Other jet mixing parameters such as the centerline total temperature decay and the centerline velocity of the jet flow exiting each nozzle are also analyzed. A 2-D axisymmetric grid is produced for the 3BB nozzle while a 3-D mesh is generated for each of the chevron nozzles. To reduce the computation cost, only a 30° sector of the chevron nozzles is modeled. Since the Shear Stress Transport (SST) k-ω turbulence model has been widely used in several aerospace applications, it is chosen for all simulations here as well. The numerical analysis shows that STAR-CCM+ can successfully be used for the study…
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering
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APA (6th Edition):
Mullick, S. (2017). IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/25896
Chicago Manual of Style (16th Edition):
Mullick, Sunayan. “IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS.” 2017. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/25896.
MLA Handbook (7th Edition):
Mullick, Sunayan. “IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS.” 2017. Web. 18 Jan 2021.
Vancouver:
Mullick S. IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS. [Internet] [Masters thesis]. University of Kansas; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/25896.
Council of Science Editors:
Mullick S. IMPACT OF NEW CHEVRON CONFIGURATIONS ON MIXING ENHANCEMENT IN SUBSONIC JETS. [Masters Thesis]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/25896
19.
Kolpuke, Shriniwas.
Bio-inspired Navigation Algorithm for GPS Denial Modes.
Degree: MS, Aerospace Engineering, 2017, University of Kansas
URL: http://hdl.handle.net/1808/25760
► The wide use of the Global Positioning System (GPS) for navigation has been persistent for a long time. However, in today’s scenario when technologies are…
(more)
▼ The wide use of the Global Positioning System (GPS) for navigation has been persistent for a long time. However, in today’s scenario when technologies are advancing the accuracy of positioning systems, there are various new threats and challenges emerging. The signal receivers for positioning systems are prone to spoofing. This external interference in the system is usually done by feeding false signal to the receiver. Though the dead reckoning method is still in use, any interference with GPS can still lead to disaster. Insects and birds are known to use solar position for guidance and it is widely accepted by researchers that some birds, such as pigeons, use solar position in their homing flight. There are similar studies performed on honeybees and monarch butterflies. The use of solar position by these insects and birds brings up the question of whether a mathematical model can be used to replicate the results for real-life navigation and can a bio-inspired navigation algorithm like this be implemented. Solar position algorithms are already in wide use. The solar position algorithms available calculate the azimuth and zenith/incidence angles for the solar position at any given point of time when the position of the observer is known. The objective for navigation is to find an observer’s position from solar position to present an alternative to GPS for navigational use. This document proposes the method for calculating the observer’s position when the azimuth and zenith/incidence angles for the solar position, attitude of aircraft and the accurate time are known. The approach proposed is that the position of the observer is to be calculated by adopting the concept of reversing the ENEA algorithm where instead of calculating the solar position using an observer’s position, one will be calculating the position of the observer from the solar position and time.
Advisors/Committee Members: Keshmiri, Shawn (advisor), McLaughlin, Craig (cmtemember), Taghavi, Ray (cmtemember).
Subjects/Keywords: Aerospace engineering; Bio-inspired; GPS; GPS Denial Modes; Navigation
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APA (6th Edition):
Kolpuke, S. (2017). Bio-inspired Navigation Algorithm for GPS Denial Modes. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/25760
Chicago Manual of Style (16th Edition):
Kolpuke, Shriniwas. “Bio-inspired Navigation Algorithm for GPS Denial Modes.” 2017. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/25760.
MLA Handbook (7th Edition):
Kolpuke, Shriniwas. “Bio-inspired Navigation Algorithm for GPS Denial Modes.” 2017. Web. 18 Jan 2021.
Vancouver:
Kolpuke S. Bio-inspired Navigation Algorithm for GPS Denial Modes. [Internet] [Masters thesis]. University of Kansas; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/25760.
Council of Science Editors:
Kolpuke S. Bio-inspired Navigation Algorithm for GPS Denial Modes. [Masters Thesis]. University of Kansas; 2017. Available from: http://hdl.handle.net/1808/25760
20.
Bodlak, Eric.
The Design Space Exploration and Preliminary Testing of a New Class of Tailsitting Quadrotor Aircraft.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/24135
► Within the last decade, multi-rotor aircraft have become the most prevalent form of unmanned aerial vehicle (UAV), with applications in the military, commercial, and civilian…
(more)
▼ Within the last decade, multi-rotor aircraft have become the most prevalent form of unmanned aerial vehicle (UAV), with applications in the military, commercial, and civilian sectors. This is due primarily to advances in electronics that allow small-scale aircraft systems to be produced and controlled in an affordable manner. Such systems are maneuvered by precisely varying the thrust and torque of individual rotors to produce flight control forces, thereby eliminating much of the mechanical complexity inherent in conventional helicopter configurations. Although many UAV missions exploit the ability to hover in place, many also require the ability to quickly and efficiently dash from point to point. Rotorcraft, in general, are limited in this capacity, since rotor thrust must also be used to produce lift. Transitional aircraft represent an alternative that blends the vertical take-off and landing (VTOL) capabilities of rotorcraft with the forward flight performance of fixed-wing aircraft, but they often rely on cumbersome mechanisms, such as additional or rotating powerplants. UAVs, however, have no need to maintain cockpit orientation. Consequently, a tailsitting quadcopter concept was devised by Dr. Ron Barrett to combine quadcopter hovering performance with the high-speed flight of fixed-wing craft. This paper lays out the arguments for such an aircraft — the XQ-139 — and examines the performance of XQ-139 variants with installed power values ranging from 100 W to 10,000 kW. Battery-electric, rotary engine, turboprop, and hybrid propulsive options are considered, and the merits of each discussed. Additionally, an XQ-139 prototype was designed and constructed, and stationary test was used to compare the aircraft’s installed efficiency with that of a typical quadcopter. The prototype was found to be approximately 5% more efficient in hover mode than the quadcopter to which it was compared.
Advisors/Committee Members: Barrett, Ron (advisor), Keshmiri, Shawn (cmtemember), Taghavi, Ray (cmtemember).
Subjects/Keywords: Aerospace engineering; aircraft; design; quadrotor; scaling; tailsitter; VTOL
…KUTRI . . . . . University of Kansas Transportation Research Institute.
LFP… …projected gross weight of 10,000-12,000 pounds
11
The University of Kansas Transportation…
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APA (6th Edition):
Bodlak, E. (2016). The Design Space Exploration and Preliminary Testing of a New Class of Tailsitting Quadrotor Aircraft. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/24135
Chicago Manual of Style (16th Edition):
Bodlak, Eric. “The Design Space Exploration and Preliminary Testing of a New Class of Tailsitting Quadrotor Aircraft.” 2016. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/24135.
MLA Handbook (7th Edition):
Bodlak, Eric. “The Design Space Exploration and Preliminary Testing of a New Class of Tailsitting Quadrotor Aircraft.” 2016. Web. 18 Jan 2021.
Vancouver:
Bodlak E. The Design Space Exploration and Preliminary Testing of a New Class of Tailsitting Quadrotor Aircraft. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/24135.
Council of Science Editors:
Bodlak E. The Design Space Exploration and Preliminary Testing of a New Class of Tailsitting Quadrotor Aircraft. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/24135
21.
Karwas, Alex A.
An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion.
Degree: PhD, Aerospace Engineering, 2015, University of Kansas
URL: http://hdl.handle.net/1808/19374
► Solar sails use the endless supply of the Sun's radiation to propel spacecraft through space. The sails use the momentum transfer from the impinging solar…
(more)
▼ Solar sails use the endless supply of the Sun's radiation to propel spacecraft through space. The sails use the momentum transfer from the impinging solar radiation to provide thrust to the spacecraft while expending zero fuel. Recently, the first solar sail spacecraft, or sailcraft, named IKAROS completed a successful mission to Venus and proved the concept of solar sail propulsion. Sailcraft experimental data is difficult to gather due to the large expenses of space travel, therefore, a reliable and accurate computational method is needed to make the process more efficient. Presented in this document is a new approach to simulating solar sail spacecraft trajectories. The new method provides unconditionally stable numerical solutions for trajectory propagation and includes an improved physical description over other methods. The unconditional stability of the new method means that a unique numerical solution is always determined. The improved physical description of the trajectory provides a numerical solution and time derivatives that are continuous throughout the entire trajectory. The error of the continuous numerical solution is also known for the entire trajectory. Optimal control for maximizing thrust is also provided within the framework of the new method. Verification of the new approach is presented through a mathematical description and through numerical simulations. The mathematical description provides details of the sailcraft equations of motion, the numerical method used to solve the equations, and the formulation for implementing the equations of motion into the numerical solver. Previous work in the field is summarized to show that the new approach can act as a replacement to previous trajectory propagation methods. A code was developed to perform the simulations and it is also described in this document. Results of the simulations are compared to the flight data from the IKAROS mission. Comparison of the two sets of data show that the new approach is capable of accurately simulating sailcraft motion. Sailcraft and spacecraft simulations are compared to flight data and to other numerical solution techniques. The new formulation shows an increase in accuracy over a widely used trajectory propagation technique. Simulations for two-dimensional, three-dimensional, and variable attitude trajectories are presented to show the multiple capabilities of the new technique. An element of optimal control is also part of the new technique. An additional equation is added to the sailcraft equations of motion that maximizes thrust in a specific direction. A technical description and results of an example optimization problem are presented. The spacecraft attitude dynamics equations take the simulation a step further by providing control torques using the angular rate and acceleration outputs of the numerical formulation.
Advisors/Committee Members: Taghavi, Ray (advisor), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember), Zheng, Zhongquan Charlie (cmtemember), Yimer, Bedru (cmtemember).
Subjects/Keywords: Aerospace engineering; Finite Element Method; Propagation; Sailcraft; Solar Sail; Spacecraft; Trajectory
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APA (6th Edition):
Karwas, A. A. (2015). An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/19374
Chicago Manual of Style (16th Edition):
Karwas, Alex A. “An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion.” 2015. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/19374.
MLA Handbook (7th Edition):
Karwas, Alex A. “An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion.” 2015. Web. 18 Jan 2021.
Vancouver:
Karwas AA. An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion. [Internet] [Doctoral dissertation]. University of Kansas; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/19374.
Council of Science Editors:
Karwas AA. An Unconditionally Stable Method for Numerically Solving Solar Sail Spacecraft Equations of Motion. [Doctoral Dissertation]. University of Kansas; 2015. Available from: http://hdl.handle.net/1808/19374
22.
Nimmakayala, Surya Tej.
Heuristics to predict and eagerly translate code in DBTs.
Degree: PhD, Electrical Engineering & Computer Science, 2019, University of Kansas
URL: http://hdl.handle.net/1808/29617
► Dynamic Binary Translators(DBTs) have a variety of uses, like instrumentation, profiling, security, portability, etc. In order for the desired application to run with these enhanced…
(more)
▼ Dynamic Binary Translators(DBTs) have a variety of uses, like instrumentation, profiling, security, portability, etc. In order for the desired application to run with these enhanced additional features(not originally part of its design), it is to be run under the control of Dynamic Binary Translator. The application can be thought of as the guest application, to be run with in a controlled environment of the translator, which would be the host application. That way, the intended application execution flow can be enforced by the translator, thereby inducing the desired behavior in the application on the host platform(combination of Operating System and Hardware). However, there will be a run-time/execution-time overhead in the translator, when performing the additional tasks to run the guest application in a controlled fashion. This run-time overhead has been limiting the usage of DBT's on a large scale, where response times can be critical. There is often a trade-off between the benefits of using a DBT against the overall application response time. So, there is a need to research/explore ways to faster application execution through DBT's(given their large code-base). With the evolution of the multi-core and GPU hardware architectures, multilpe concurrent threads can get more work done through parallelization. A proper design of parallel applications or parallelizing parts of existing serial code, can lead to improved application run-time's through hardware architecture support. We explore the possibility of improving the performance of a DBT named DynamoRIO. The basic idea is to improve its performance by speeding-up the process of guest code translation, through multiple threads translating multiple pieces of code concurrently. In an ideal case, all the required code blocks for application execution are readily available ahead of time without any stalls. For efficient eager translation, there is also a need for heuristics to better predict the next code block to be executed. That could potentially bring down the less productive code translations at run-time. The goal is to get application speed-up through eager translation and block prediction heuristics, with execution time close to native run.
Advisors/Committee Members: Kulkarni, Prasad A (advisor), Luo, Bo (cmtemember), Li, Fengjun (cmtemember), Alexander, Perry (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Computer science; Computer engineering; data-mining; dynamic binary translation; heuristics; startup overhead
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APA (6th Edition):
Nimmakayala, S. T. (2019). Heuristics to predict and eagerly translate code in DBTs. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/29617
Chicago Manual of Style (16th Edition):
Nimmakayala, Surya Tej. “Heuristics to predict and eagerly translate code in DBTs.” 2019. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/29617.
MLA Handbook (7th Edition):
Nimmakayala, Surya Tej. “Heuristics to predict and eagerly translate code in DBTs.” 2019. Web. 18 Jan 2021.
Vancouver:
Nimmakayala ST. Heuristics to predict and eagerly translate code in DBTs. [Internet] [Doctoral dissertation]. University of Kansas; 2019. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/29617.
Council of Science Editors:
Nimmakayala ST. Heuristics to predict and eagerly translate code in DBTs. [Doctoral Dissertation]. University of Kansas; 2019. Available from: http://hdl.handle.net/1808/29617
23.
Giridhar, Rohith.
Prediction of Aerodynamic Noise Generated By Wind Turbine Blades.
Degree: MS, Aerospace Engineering, 2016, University of Kansas
URL: http://hdl.handle.net/1808/21976
► The preliminary step in the computational study of mitigating the aerodynamic noise generated by wind turbine blades involves accurate prediction of aerodynamic noise generated by…
(more)
▼ The preliminary step in the computational study of mitigating the aerodynamic noise generated by wind turbine blades involves accurate prediction of aerodynamic noise generated by a wind turbine rotor which can be used a basis for comparison. The NREL Phase VI HAWT rotor has been chosen to perform this study. This is achieved by first predicting the three dimensional flow field around the rotor through CFD analysis using SST k-ω turbulence model for wind speeds of 7m/s, 10m/s, 13m/s and 15m/s. CFD analysis has been performed using the rotating reference frame method at steady state conditions which resulted in predicting the flow field accurately with less computational time. The rotational periodic boundary condition with 1800 symmetry has been used with which one blade has been simulated instead of two. This reduced the mesh size and thus computational costs to perform the CFD analysis. To validate the prediction of flow field obtained through CFD analysis, performance characteristics and aerodynamic characteristics such as torque generated and trends of pressure coefficients at different span locations are validated against the time averaged experimental results and other results pertaining to the same published in previous computational study. The results obtained through CFD analysis show good agreement with both experimental results and previous computational results. Based on the trends of pressure coefficients predicted for different wind speeds we see that it is most accurate at a wind speed of 7m/s and this accuracy gradually decreases with increase in wind speed. Once the flow field was accurately predicted, this was used to predict both the location and magnitude of aerodynamic noise generated by the blade using the Curle broadband noise source model. Aeroacoustic analysis indicates that major noise sources are located near the tip of the blade and it gradually decreases as we move towards its root. This trend is observed at all four wind speed conditions. It is also observed that with increase in wind speeds, there is increase in the intensity of noise generated by the blades and thus increase in Sound Power Level across the blade.
Advisors/Committee Members: Farokhi, Saeed (advisor), Farokhi, Saeed (cmtemember), Taghavi, Ray (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering; Aero acoustics; Aerodynamic Noise; Curle; NREL Phase VI; SST k-omega; Wind Turbine Noise
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APA (6th Edition):
Giridhar, R. (2016). Prediction of Aerodynamic Noise Generated By Wind Turbine Blades. (Masters Thesis). University of Kansas. Retrieved from http://hdl.handle.net/1808/21976
Chicago Manual of Style (16th Edition):
Giridhar, Rohith. “Prediction of Aerodynamic Noise Generated By Wind Turbine Blades.” 2016. Masters Thesis, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/21976.
MLA Handbook (7th Edition):
Giridhar, Rohith. “Prediction of Aerodynamic Noise Generated By Wind Turbine Blades.” 2016. Web. 18 Jan 2021.
Vancouver:
Giridhar R. Prediction of Aerodynamic Noise Generated By Wind Turbine Blades. [Internet] [Masters thesis]. University of Kansas; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/21976.
Council of Science Editors:
Giridhar R. Prediction of Aerodynamic Noise Generated By Wind Turbine Blades. [Masters Thesis]. University of Kansas; 2016. Available from: http://hdl.handle.net/1808/21976
24.
Sizemore, Alex.
Improved Atmospheric Density Estimation and Characterization of Uncertainty.
Degree: PhD, Aerospace Engineering, 2018, University of Kansas
URL: http://hdl.handle.net/1808/27610
► Precise knowledge of the density in the upper atmosphere is a vital component of the orbit determination process for low Earth orbit, as inaccuracies in…
(more)
▼ Precise knowledge of the density in the upper atmosphere is a vital component of the orbit determination process for low Earth orbit, as inaccuracies in the estimation of atmospheric drag are the primary source of uncertainty for satellites in low Earth orbit. The need for a more accurate knowledge of the density of the upper atmosphere has led to the development of atmospheric density derived from precision satellite orbits. This method, using the Precise Orbit Ephemerides (POE) for a satellite, requires refinement and validation before it can be used on a larger scale. Additionally, the uncertainty of this method is not well documented. To improve these atmospheric density models, the POE densities are calculated and compared to the accelerometer derived densities for a majority of the lifetime of both the Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites to provide a more robust understanding of the effectiveness of these models. Additionally, the framework has been set so that future satellite missions can easily be ingested and analyzed without a substantial amount of work. In a few locations in the accelerometer derived densities, there are gaps that must be filled. By using a separate accelerometer density method, the first, more reliable accelerometer method can be patched in these locations to allow for a much more robust method. This combined density allows for a more effective evaluation of the POE densities. To further improve the estimates of atmospheric density, the four Atmospheric Neutral Density Experiment (ANDE) satellites are considered. These spherical satellites provide a much simpler analysis of the atmospheric drag than the much more complicated geometry of the established CHAMP and GRACE satellites. To further improve the estimates for the ANDE satellites, a series of methods to more accurately model the drag coefficients for these satellites are studied and applied to the orbit determination process. In addition to the ANDE satellites, the CHAMP and GRACE satellites drag coefficients were updated to include a higher fidelity drag coefficient and projected area model. Using these drag coefficients, the atmospheric densities are estimated, and the uncertainty associated with the estimation process is saved. The returned atmospheric densities for the CHAMP and GRACE satellites show a marked improvement in the RMS values when compared to the accelerometer derived densities. Next, a method of validating the ANDE results is examined. By examining both the uncertainty in the atmospheric density estimate and the error as compared to the accelerometer derived densities for both the CHAMP and GRACE satellites, a scale factor relating these two variables is studied. This method provides a daily scale factor to adjust the uncertainties in the atmospheric density estimate to determine the root mean square (RMS) error for the ANDE satellites. These RMS values are then separated into several geomagnetic and solar activity bins that allow for a better…
Advisors/Committee Members: McLaughlin, Craig A (advisor), Cravens, Thomas (cmtemember), Ewing, Mark (cmtemember), Farokhi, Saeed (cmtemember), Keshmiri, Shawn (cmtemember).
Subjects/Keywords: Aerospace engineering
…Los Alamos and The University of Kansas as
presented in McLaughlin et. al. [3]…
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APA (6th Edition):
Sizemore, A. (2018). Improved Atmospheric Density Estimation and Characterization of Uncertainty. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/27610
Chicago Manual of Style (16th Edition):
Sizemore, Alex. “Improved Atmospheric Density Estimation and Characterization of Uncertainty.” 2018. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/27610.
MLA Handbook (7th Edition):
Sizemore, Alex. “Improved Atmospheric Density Estimation and Characterization of Uncertainty.” 2018. Web. 18 Jan 2021.
Vancouver:
Sizemore A. Improved Atmospheric Density Estimation and Characterization of Uncertainty. [Internet] [Doctoral dissertation]. University of Kansas; 2018. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/27610.
Council of Science Editors:
Sizemore A. Improved Atmospheric Density Estimation and Characterization of Uncertainty. [Doctoral Dissertation]. University of Kansas; 2018. Available from: http://hdl.handle.net/1808/27610
25.
Rahmaninezhad, Seyed Mustapha Mustapha.
Geosynthetic-Reinforced Retaining Walls with Flexible Facing Subjected to Footing Loading.
Degree: PhD, Civil, Environmental & Architectural Engineering, 2019, University of Kansas
URL: http://hdl.handle.net/1808/29690
► Geosynthetic-reinforced retaining (GRR) walls have been used as bridge abutments to support shallow foundations. This technology eliminates the need for traditional deep foundations, such as…
(more)
▼ Geosynthetic-reinforced retaining (GRR) walls have been used as bridge abutments to support shallow foundations. This technology eliminates the need for traditional deep foundations, such as piles, to support bridges. However, limited studies have been conducted so far to evaluate the performance of GRR abutment walls constructed with flexible facing. The objectives of this study were: (1) to evaluate the performance of the GRR walls subjected to static footing loading and (2) to develop methods to predict facing lateral deflections and surface settlement of GRR walls under the footing loading. To fulfill the above research objectives, a comprehensive experimental study and analytical analysis were conducted. In this study, pullout tests were conducted to evaluate the effect of the load application method using an airbag with and without stiff plates on the vertical stress distribution and the pullout capacities and deflections of extensible (geogrid) reinforcement in the soil in a large pullout box. The non-uniform pressure distribution resulting from the airbag with stiff plates reduced the pullout resistance of the reinforcement as compared with that without stiff plates. The test results also show that the displacements in the cross section of the same transverse bar were not equal when the normal load was applied through stiff plates. This study investigated the combined effects of tension, bending, and friction on the measured strains on the upper and lower sides of uniaxial geogrid specimens by wrapping the specimen around a cylinder of different diameters. The test results show the combination of tension, bending, and friction reduced the average upper and lower strains by 28% as compared with the tension only. The cylinder diameter did not have any effect on the measured strains of the geogrid on the cylinder. The experimental study investigated eight reduced-scale GRR abutment walls with wrapped-around and modular concrete block facing subjected to static footing loading in a test box under a plane strain condition. The settlements of the footing, the lateral deflections of the facing, the vertical and lateral earth pressures, the tensile strains along reinforcement, and the failure mode were evaluated. The test results showed that the modular block facing acting as a relatively rigid structural element reduced the footing settlement as compared with the wrapped-around facing. Moreover, the maximum lateral deflection in the wrapped-around facing wall was much larger than that of the modular block facing wall under the same applied footing pressure. The measured maximum vertical stress was larger than the calculated stress from the Boussinesq equation and the 2:1 distribution method at the centerline of the footing. The maximum lateral earth pressure was recorded at the depth of 0.5H-0.7H and 0.9H (H is the wall height) from the top of the walls with modular block and wrapped facing, respectively. The Boussinesq equation was used to calculate the lateral earth pressure induced by footing loading, which…
Advisors/Committee Members: Han, Jie (advisor), Cai, Hongyi (cmtemember), Keshmiri, Shawn (cmtemember), Parsons, Robert L. (cmtemember), Schrock, Steven D. (cmtemember).
Subjects/Keywords: Civil engineering; Gender studies; Abutment; Bridge; Geosynthetic; Retaining Wall
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APA (6th Edition):
Rahmaninezhad, S. M. M. (2019). Geosynthetic-Reinforced Retaining Walls with Flexible Facing Subjected to Footing Loading. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/29690
Chicago Manual of Style (16th Edition):
Rahmaninezhad, Seyed Mustapha Mustapha. “Geosynthetic-Reinforced Retaining Walls with Flexible Facing Subjected to Footing Loading.” 2019. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/29690.
MLA Handbook (7th Edition):
Rahmaninezhad, Seyed Mustapha Mustapha. “Geosynthetic-Reinforced Retaining Walls with Flexible Facing Subjected to Footing Loading.” 2019. Web. 18 Jan 2021.
Vancouver:
Rahmaninezhad SMM. Geosynthetic-Reinforced Retaining Walls with Flexible Facing Subjected to Footing Loading. [Internet] [Doctoral dissertation]. University of Kansas; 2019. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/29690.
Council of Science Editors:
Rahmaninezhad SMM. Geosynthetic-Reinforced Retaining Walls with Flexible Facing Subjected to Footing Loading. [Doctoral Dissertation]. University of Kansas; 2019. Available from: http://hdl.handle.net/1808/29690
26.
Legursky, Katrina.
System Identification and the Modeling of Sailing Yachts.
Degree: PhD, Aerospace Engineering, 2013, University of Kansas
URL: http://hdl.handle.net/1808/14198
► This research represents an exploration of sailing yacht dynamics with full-scale sailing motion data, physics-based models, and system identification techniques. The goal is to provide…
(more)
▼ This research represents an exploration of sailing yacht dynamics with full-scale sailing motion data, physics-based models, and system identification techniques. The goal is to provide a method of obtaining and validating suitable physics-based dynamics models for use in control system design on autonomous sailing platforms, which have the capacity to serve as mobile, long range, high endurance autonomous ocean sensing platforms. The primary contributions of this study to the state-of-the-art are the formulation of a five degree-of-freedom (DOF) linear multi-input multi-output (MIMO) state space model of sailing yacht dynamics, the process for identification of this model from full-scale data, a description of the maneuvers performed during on-water tests, and an analysis method to validate estimated models. The techniques and results described herein can be directly applied to and tested on existing autonomous sailing platforms. A full-scale experiment on a 23ft monohull sailing yacht is developed to collect motion data for physics-based model identification. Measurements include 3 axes of accelerations, velocities, angular rates, and attitude angles in addition to apparent wind speed and direction. The sailing yacht herein is treated as a dynamic system with two control inputs, the rudder angle, dR, and the mainsail angle, dB, which are also measured. Over 20 hours of full scale sailing motion data is collected, representing three sail configurations corresponding to a range of wind speeds: the Full Main and Genoa (abbrev. Genoa) for lower wind speeds, the Full Main and Jib (abbrev. Jib) for mid-range wind speeds, and the Reefed Main and Jib (abbrev. Reef) for the highest wind speeds. The data also covers true wind angles from upwind through a beam reach. A physics-based non-linear model to describe sailing yacht motion is outlined, including descriptions of methods to model the aerodynamics and hydrodynamics of a sailing yacht in surge, sway, roll, and yaw. Existing aerodynamic models for sailing yachts are unsuitable for control system design as they do not include a physical description of the sails' dynamic effect on the system. A new aerodynamic model is developed and validated using the full-scale sailing data which includes sail deflection as a control input to the system. The Maximum Likelihood Estimation (MLE) algorithm is used with non-linear simulation data to successfully estimate a set of hydrodynamic derivatives for a sailing yacht. As there exists a large quantify of control algorithms which may be applied to systems described by a linear model, the non-linear model is simplified to a 5DOF MIMO state space model with a state vector including surge velocity, sway velocity, roll rate, yaw rate, and roll angle: , and a control vector: . Over 100 singlet and doublet maneuvers specifically designed to identify linear model dynamic responses are included in the full-scale data. The one-shot least squares (OSLS) technique offered a simple and fast means to estimate many linear models from this large…
Advisors/Committee Members: Hale, Richard (advisor), Keshmiri, Shawn S (advisor), Ewing, Mark (cmtemember), Young, Bryan (cmtemember), Downing, David R (cmtemember).
Subjects/Keywords: Aerospace engineering; Ocean engineering; Autonomous sailboat; Full-scale data; One-shot least squares; Sailing yacht dynamics; System identification; Yacht modeling
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
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Manager
APA (6th Edition):
Legursky, K. (2013). System Identification and the Modeling of Sailing Yachts. (Doctoral Dissertation). University of Kansas. Retrieved from http://hdl.handle.net/1808/14198
Chicago Manual of Style (16th Edition):
Legursky, Katrina. “System Identification and the Modeling of Sailing Yachts.” 2013. Doctoral Dissertation, University of Kansas. Accessed January 18, 2021.
http://hdl.handle.net/1808/14198.
MLA Handbook (7th Edition):
Legursky, Katrina. “System Identification and the Modeling of Sailing Yachts.” 2013. Web. 18 Jan 2021.
Vancouver:
Legursky K. System Identification and the Modeling of Sailing Yachts. [Internet] [Doctoral dissertation]. University of Kansas; 2013. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1808/14198.
Council of Science Editors:
Legursky K. System Identification and the Modeling of Sailing Yachts. [Doctoral Dissertation]. University of Kansas; 2013. Available from: http://hdl.handle.net/1808/14198
. 
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