Coordination method in design of forming operations of hierarchical solid objects
The application of the coordination technology in the design of forming operations is regarded. The coordination design method was developed by using hierarchical systems construction and dynamic systems (by M. Mesarovich and Y. Takahara), numeric positional systems, and aed formal model (by S. Novikava). Solid objects being designed and their forming operations were presented in hierarchical form taking under consideration the objectpsilas structure, its external presentation as the unit in environment system and the environment system construction. All the design and control actions are executed by coordinator on its selection, learning and self-organization layers by one of coordination strategy. Theoretical basis description and computer realization of the proposed coordination technology for the exemplary forming tasks solving are also presented in the paper.
Special issue on geometric modeling and processing
The international Conference on Geometric Modeling and Processing was held in Beijing, China from April 13 to 15, 2004. Being the third in a biennial conference series, it brought together le researchers in the field of Geometric Computing. This special issue contains improved and e versions of selected presentations at GMP 2004. The first paper, by Clarenz, Litke and Rumpf, presents a new framework for surface paramete which is derived from first principles within a variational formulation. It is related to the theory of linear elasticity and based on the minimization of an appropriate functional, which contains para for the control of angle, area and length distortion between the parameter domain and the given A Newton method with step size control is used for the numerical solution of the optimization pro The authors show a number of impressive examples comparing the new approach with othe parameterization methods. Surface parameterization is also addressed, in a quite different way, by Nielson et al. The surf assumed to be isosurfaces produced by the marching cubes algorithm. The remarkable aspect of is that it actually contains a transfer principle from parameterization methods for curves to surfa appropriate curve networks. In this sense, this work has a similar flavor as Nielson’s classical m norm network for scattered data interpolation (Nielson, 1983). The third paper, by G. Xu, also falls into the area of computational differential geometry of sur It proposes and analyzes the convergence of new discretizations of the Laplace–Beltrami ope surface triangulations. This operator, an extension of the Laplace operator in the plane to curved s plays a fundamental role in a number of important applications such as surface flows. Xu illustra via surface smoothing, surface restoration and the construction of blending surfaces. Whereas a general surface patch cannot be parameterized over the plane without length disto class of developable surfaces has this nice geometric property. M. Peternell addresses geometric ing with these special surfaces. He shows how to use a classical model for the set of oriented p 3-space, the so-called Blaschke cylinder of Laguerre Geometry, for the recognition and reconstru developable surfaces from clouds of measurement points. Finally, the fifth paper, by Gao and Li, deals with the approximate conversion of planar or s real algebraic curves to piecewise rational quadratic form (conic splines). Using tools from alg geometry and graph theory, the algorithm carefully computes the topology of the curve and sp components into appropriate segments. These are then approximated by rational quadratic Bézi
APPLICATION OF THE FINITE ELEMENT METHOD TO ROTARY-WING AEROELASTICITY.
Recent research in rotary-wing aeroelasticity has indicated that all fundamental problems in this area are inherently nonlinear. The non-linearities in this problem are due to the inclusion of finite slopes, due to moderate deflections, in the structural, inertia and aerodynamic operators associated with this aeroelastic problem. In this paper the equations of motion, which are both time and space dependent, for the aeroelastic problem are first formulated in P.D.E. form. Next the equations are linearized about a suitable equilibrium position. The spatial dependence in these equations is discretized using a local Galerkin method of weighted residuals resulting in a finite element formulation of the aeroelastic problem. As an illustration the method is applied to the coupled flap-lag problem of a helicopter rotor blade in hover. Comparison of the solutions with previously published solutions establishes the convergence properties of the method. It is concluded that this formulation is a practical tool for solving rotary-wing aeroelastic stability or response problems.