Papers by Keyword: Moments

Abstract: This article is about the nonlinear problems of the theory of elastic Cosserat – Timoshenko’s rods in the material (Lagrangian) description with energy conjugated vectors of forces, moments and strains. The variational formulations of static problems was given. The differential equations of the plane stability problems were obtained from the second variation of the Lagrangian functional. The exact solutions of the stability problems for basic types of the end fixities of the rod were obtained for the Timoshenko’s rod (taking into account only bending and shear stiffness). It appears that classical well-known equilibrium stability functional and stability equations for the Timoshenko’s rod are incorrect. Also well-known Engesser formula (with bending and shear stiffness) is incorrect. The numerical solution of the stability problems for hinged Timoshenko’s rod with rigid support was obtained. Also, simplified formula for this problem was derived using asymptotic analysis.

Abstract: There are many calculation methods of horizontal borehole trajectory, such as cubic spline interpolation function which is based on three-moment equation. By calculating the moments of deviation and azimuth from cubic spline interpolation function respectively, it is easy obtain functions of deviation and azimuth change rate and average borehole curvature to analysis on curving of borehole trajectory. So it is one of the most common methods. However, the moments are always be neglected. Moments of deviation and azimuth, which could be used to qualitatively estimate borehole trajectory curving, are first proposed tentatively in this paper. Synthetically employing other useful parameters of estimation borehole trajectory curving, tens of high-angle directional and horizontal wells’ drilling data is computed and analyzed. Contrast to the variation characteristics of deviation and azimuth change rate, the deviation and azimuth moments have the similar change tendency respectively. The results of this study signify that the proposed parameters could provide some reference for assessment on borehole trajectory curving.

Abstract: In the past decades, the theories of invariant moments have been researched extensively and wildly used in many fields. However, for the laser-welding spots of titanium tubes or other fixed objects, the invariant moments are inapplicable. Besides, the studies and experiments about image classification by means of the original moment values were barely proposed. In this paper, the method of classification based on original moment values is introduced, and an improved approach of KPCA (kernel principal component analysis) in order to reduce the inner-class distance of the qualified laser-welding spots is also discussed. Finally, experiments are carried out to validate the classification ability, and results show that the original moment values are suited as pattern features in classification of fixed objects.

Abstract: In this paper, we discuss one kind of Markov Skeleton processes, nonhomogeneous (H,Q) processes. We mainly study their distributions and moments of the first entrance time, and we obtain their recursive formula and some related properties.

Abstract: In this paper we discuss one kind of nonhomogeneous (H,Q) processes, Nonhomogeneous Semi-Markov Process. We get the distributions and moments of the first entrance time for this process. And furthermore, we obtain their recursive formula.

Abstract: The mechanical actions measurement can highlight a series of mechanical phenomena occurring in the cutting process. During the experiments, we use a six-component dynamometer to measured the forces and the moments applied by the tool to the workpiece. In this paper, the authors present a method for determining the cutting tool position in drilling process, with purpose to transport of the moments (calculation of the torsor in each of the holes). Then can be achieved analyze of the forces and moments for every hole.

Abstract: The better understanding of the material cutting process has been shown with the benefit of the forces and moments measurement since some years ago. In paper, simultaneous six mechanical components and chip orientation measurements were realized during turning tests. During these tests, the influence of the depth of cut or feed rate has been observed and a link between the chip orientation and the moment vector orientation or the central axis characteristics has been shown. Nomenclature * corresponding author