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## Full-Text Articles in Engineering

Parallel Surface Reconstruction Through Virtual Milling , Kumaran Kalyanasundaram

#### Parallel Surface Reconstruction Through Virtual Milling , Kumaran Kalyanasundaram

*Retrospective Theses and Dissertations*

Surface definition deals with representing a surface analytically using a finite number of parameters and with acceptable levels of error. In the past few years it has become a key discipline in Computational Fluid Dynamics (CFD). Recent advances in computers and numerical algorithms have made it possible for CFD practitioners to attempt flow solutions about complex three-dimensional geometries. The first step in this process is having a numerical representation of the shape. In many cases of interest such a representation already exists; i.e., aircraft designed on a computer. Such Computer-Aided Design (CAD) descriptions do not exist, though, for objects ...

Adaptive Nonlinear Attitude Control Of Spacecraft , Cheng Tang

#### Adaptive Nonlinear Attitude Control Of Spacecraft , Cheng Tang

*Retrospective Theses and Dissertations*

Three adaptive nonlinear control approaches are proposed for attitude control of a Space Station. These control algorithms avoid the need for linearization, either by truncating a Taylor series or by a feedback linearization approach, which poses some difficulties in the presence of both uncertain mass properties and external disturbances. Global stability of the Space Station is guaranteed;A conventional linear-quadratic regulator synthesis technique is investigated. This linear control scheme provides a natural way to select control gains for the known spacecraft system parameters. Simulation results reveal that the uncertain mass property causes the nonlinear Space Station to be uncontrollable;On ...

Optimal Turning Maneuvers For Six-Degree-Of-Freedom High Angle-Of-Attack Aircraft Models , Jen-Nai Chou

#### Optimal Turning Maneuvers For Six-Degree-Of-Freedom High Angle-Of-Attack Aircraft Models , Jen-Nai Chou

*Retrospective Theses and Dissertations*

Various Minimum-Time Turning Maneuvers for two high angle-of-attack, six-degree-of-freedom, aircraft models have been investigated. The primary aircraft model is for a nonlinear 6-DOF F-16 fighter aircraft with high angle-of-attack maneuverability. The other model is for a linearized 6-DOF F-18 fighter which also can be flown in the high angle-of-attack range. Standard 6-DOF equations are employed except that the Quaternion attitude representation system is used instead of Euler Angles to avoid the pitch angle singularity of Euler Angles;These Optimal Control problems have been transformed into Nonlinear Programming problems via Parameter Optimization techniques. Different parameterization techniques were tested on the Van ...

#### Coupled Compressible And Incompressible Finite Volume Formulations For The Large Eddy Simulation Of Turbulent Flow With And Without Heat Transfer , Wen-Ping Wang

*Retrospective Theses and Dissertations*

A coupled finite volume approach for solving the time-dependent Navier-Stokes equations is developed for application to the large eddy simulation (LES) of turbulent flow. The preconditioning strategy of coupling the incompressible N-S equations and providing acceleration of iterative convergence in both compressible and incompressible formulations is employed. Three different spatial discretization schemes along with the regular/staggered grid arrangements are evaluated on both two-dimensional laminar flows and three-dimensional turbulent flows;No distinctive differences are found in laminar flow cases, but the staggered grid appears to provide a better resolution of the turbulence statistics over a regular one in the simulation ...