Minimum contact stress modification for profile curve design defects in the beam-spring-cone docking mechanism

A minimum contact stress modification method for profile curve design defects in a beam-spring-cone docking mechanism (BSCDM) based on genetic algorithm is presented in this paper, the profile curve and contact position of BSCDM are optimized. Under low-speed conditions, an improved elastic contact model of semi-space elastic bodies is established to modify and optimize the elliptic profile envelope curve based on Hertz contact theory and two kinds of complete elliptic integral, the improved contact model is used to solve elastic contact problems with the geometric characteristics of the ellipse surface, the optimal profile curve of the docking joint and the optimal docking contact point position are obtained. The results of numerical simulation and the experiment demonstrate the feasibility and validity of above models and methods.

On the Reconstruction of the Center of a Projection by Distances and Incidence Relations

Up to an orientation-preserving symmetry, photographic images are produced by a central projection of a restricted area in the space into the image plane. To obtain reliable information about physical objects and the environment through the process of recording is the basic problem of photogrammetry. We present a reconstruction process based on distances from the center of projection and incidence relations among the points to be projected. For any triplet of collinear points in the space, we construct a surface of revolution containing the center of the projection. It is a generalized conic that can be represented as an algebraic surface. The rotational symmetry allows us to restrict the investigations to the defining polynomial of the profile curve in the image plane. An equivalent condition for the boundedness is given in terms of the input parameters, and it is shown that the defining polynomial of the profile curve is irreducible.

Surfaces of Revolution and Canal Surfaces with Generalized Cheng–Yau 1-Type Gauss Maps

In the present work, the notion of generalized Cheng–Yau 1-type Gauss map is proposed, which is similar to the idea of generalized 1-type Gauss maps. Based on this concept, the surfaces of revolution and the canal surfaces in the Euclidean three-space are classified. First of all, we show that the Gauss map of any surfaces of revolution with a unit speed profile curve is of generalized Cheng–Yau 1-type. At the same time, an oriented canal surface has a generalized Cheng–Yau 1-type Gauss map if, and only if, it is an open part of a surface of revolution or a torus.

Application of profile joints of various types and standard sizes

The features of the use of profile connections in small-sized pumping units and large-size prefabricated railway wheels are considered. Keywords RC-profile, profile curve, diameter, plunger pump, railway wheel. [email protected]

Sharpness indicator of aerial- and space images obtained for mapping purposes

The main characteristics of aerial- and space imagery, obtained for mapping purposes, are the distinct details transferring and sharpness, which determine their visual properties. The sharpness of aerial- and space images affects the accuracy of measurements made on them, as well as the quality products obtained. The ability of the image to transfer fine details is separately determined by its actual spatial resolution. It is shown that the actual resolution does not completely represent the structural-and-geometric characteristics of the images’ fine quality. Calculations showing that neither actual spatial resolution nor the gradation characteristic “local contrast” make it possible to evaluate its sharpness are presented. The author proposes a method of numerically image sharpness assessing, based on the gradient characteristic of the edge profile curve. The advantage of this method in comparison with alternative ones is shown. The general form of the image sharpness criteria calculating formula for any radiometric resolution is given. The proposed method enables obtaining a normed value, varying from 0 to 1, which provides obvious interpretability of the result. The permissible value of the sharpness index of aerial and space imagery obtained for mapping is determined. Examples of images obtained by an aerial survey complex based on a light drone, as well as those obtained by a remote sensing spacecraft, satisfying the established acceptable sharpness criteria, are given. The correspondence of obtained numerical estimates to the visual perception of the image sharpness is shown.

Accurate control of residual stress distribution along the complex surface depth at the root of gears

This study aims to solve the accurate control of residual stress distribution along the depth of complex special-shaped surfaces for providing theoretical basis and experimental support for the research of anti-fatigue manufacturing of key components. Considering the complex profile curve of gear root, a scheme is proposed to predefine the complex curve of tooth root using three types of simple curves, namely, single-segment arc, arc-line combination and multisegment arc by analyzing the characteristics of tooth root shape and curve equation on the basis of meshing theory and gear tooth formation. The corresponding relationship between polishing time and depth under different schemes is calculated on the basis of the principle of electrochemistry and Faraday’s law and compared with the experimental data. On the basis of the complex profile curve of 20CrMnMo standard gear root, the relationship between polishing time and depth calculated using the three schemes is basically similar, and the curve equation is a parabola passing through the origin. The polishing time–depth relationship calculated by the predefined tooth root curve with three tangent arcs has the best agreement with the experimental data compared with the single-segment arc and arc-line combination when the layer-stripping depth is less than 400 µm. The fitting of the experimental data of tooth root polishing shows that a good parabola relationship is found between time and depth. The relationship between the polishing time and depth of tooth root can be calculated by using a simple curve to predefine a complex contour curve. Polishing depth is controlled by accurately controlling polishing time to realise accurate control of the distribution state of tooth root residual stress along the depth. The findings of this study provide theoretical basis and experimental support for future studies on the fatigue performance of key components.

PERFORMANCE INDICATORS OF ADAPTIVE FRICTION CONTACT WITH INDIRECT REGULATION

The equation of the profile curve of the slot for the rolling body of the automatic control device is obtained, this equation is used to stabilize the output parameter of the adaptive friction contact withindirect control. It is shown that the parameters of the comparison block and the additional adder are functionally dependent on the maximum coefficient of friction.