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Full-Text Articles in Engineering

Assessment Of Dynamic Effect Of Transmission Line Conductor Longitudinal Reaction Due To Downburst Loading, Ibrahim Ibrahim Dec 2017

Assessment Of Dynamic Effect Of Transmission Line Conductor Longitudinal Reaction Due To Downburst Loading, Ibrahim Ibrahim

Electronic Thesis and Dissertation Repository

Due to the locality and non-stationary nature of downburst wind loading events, their effect on the structural response of transmission line structures is of special nature that differs from conventional atmospheric boundary layer wind loading. Acknowledging such difference, the current thesis aims to quantify the dynamic effect associated with downburst loading on transmission line systems. To achieve that, several steps had to be realized, including experimentally verifying the numerical model used for analysis using wind field that was generated using computational fluid dynamics. The verified model was extended from model scale to full scale, where the wind field used for …


Hybrid Attitude Control And Estimation On So(3), Soulaimane Berkane Nov 2017

Hybrid Attitude Control And Estimation On So(3), Soulaimane Berkane

Electronic Thesis and Dissertation Repository

This thesis presents a general framework for hybrid attitude control and estimation design on the Special Orthogonal group SO(3). First, the attitude stabilization problem on SO(3) is considered. It is shown that, using a min-switch hybrid control strategy designed from a family of potential functions on SO(3), global exponential stabilization on SO(3) can be achieved when this family of potential functions satisfies certain properties. Then, a systematic methodology to construct these potential functions is developed. The proposed hybrid control technique is applied to the attitude tracking problem for rigid body systems. A smoothing mechanism is proposed to filter out the …


Estimation Of Turbulence Effects On Wind-Induced Suctions On The Roof Of A Low-Rise Building, Chieh-Hsun Wu Aug 2017

Estimation Of Turbulence Effects On Wind-Induced Suctions On The Roof Of A Low-Rise Building, Chieh-Hsun Wu

Electronic Thesis and Dissertation Repository

The effects of turbulence in the atmospheric boundary layer (ABL) on surface pressures of a typical low-rise building roof are investigated in this thesis. A 1/50 geometrically-scaled model of the Texas Tech University Wind Engineering Field Research Lab (WERFL) building model is used for pressure measurements in wind tunnel experiments. ABL wind turbulence intensities ranging from about 10% to 30%, and length scales ranging from 6 to 12 times of the building height (H) are generated. The effects of ABL turbulence on the mean roof pressures within the separated flow are explained from the time-averaged Navier-Stokes equations. The pressure fields …


Numerical Simulation Of Air Flow In Aeroengine Compressors, Shady Mohamed Mohamed Ali Jan 2017

Numerical Simulation Of Air Flow In Aeroengine Compressors, Shady Mohamed Mohamed Ali

Electronic Thesis and Dissertation Repository

The performance of an aeroengine is influenced by the performance of the compressor system. A typical compressor consists of multistage axial compressors followed by a centrifugal stage. Here, a high-speed centrifugal and an axial stage are investigated in terms of turbulence modelling, flow blockage and rotor-stator (R-S) gap using the commercial software ANSYS CFX. The curvature corrected Shear stress transport (SST-CC) model of Smirnov and Menter is investigated for the first time in a high-speed centrifugal stage in terms of curvature and rotation effects. The SST-CC predictions are compared with the standard SST, Speziale, Sarkar, and Gatski Reynolds stress model …