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Articles 1 - 4 of 4

Full-Text Articles in Engineering

Parallel Surface Reconstruction Through Virtual Milling , Kumaran Kalyanasundaram Jan 1995

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 Jan 1995

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 Jan 1995

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 Jan 1995

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 ...