A Cooperative Coevolution Wingsuit Flying Search Algorithm with Spherical Evolution

The algorithm wingsuit flying search (WFS) mimics the procedure of landing the vehicle. The outstanding feature of WFS is parameterless and of rapid convergence. However, WFS also has its shortcomings, sometimes it will inevitably be trapped into local optima, thereby yield inferior solutions owing to its relatively weak exploration ability. Spherical evolution (SE) adopts a novel spherical search pattern that takes aim at splendid search ability. Cooperative coevolution is a useful parallel structure for reconciling algorithmic performance. Considering the complementary strengths of both algorithms, we herein propose a new hybrid algorithm that is comprised of SE and WFS using cooperative coevolution. During the search for optimal solutions in WFS, we replaced the original search matrix and introduced the spherical mechanism of SE, in parallel with coevolution to enhance the competitiveness of the population. The two distinct search dynamics were combined in a parallel and coevolutionary way, thereby getting a good search performance. The resultant hybrid algorithm, CCWFSSE, was tested on the CEC2017 benchmark set and 22 CEC 2011 real-world problems. The experimental data obtained can verify that CCWFSSE outperforms other algorithms in aspects of effectiveness and robustness.

COMPARATIVE ANALYSIS OF STRESS DISTRIBUTION IN ELEMENTS OF DIFFERENT DESIGN OF HINGE JOINT OF SPHERICAL MECHANISM

Results of simulation of stress-strain state of various design solutions of hinge of spherical converting mechanism for stepless drives are considered. Comparisons of hinge loading are given when using an intermediate bushing made of various materials and without it. Recommendations for designing such an element taking into account the peculiarities of the work are justified.

Effects of Tryptophan on the Polymorphic Transformation of Calcium Carbonate: Central Composite Design, Characterization, Kinetics, and Thermodynamics

The objectives of this study were to: (i) determine the effects of tryptophan on the polymorphic phase transformation of CaCO3, (ii) investigate the thermal degradation characteristics of CaCO3 in terms of kinetics and thermodynamics using the Coats–Redfern method, and (iii) assess the influence of the experimental conditions on the vaterite composition of CaCO3 using response surface methodology based on central composite design. First, the CaCO3 crystals were prepared and analyzed using XRD, FTIR, SEM, BET, AFM, and zeta potential analysis. Based on the characterization results, the shape of the CaCO3 crystals changed from smooth cubic calcite crystals to porous irregular spherical-like vaterite crystals with increasing tryptophan concentration. Meanwhile, the kinetic results showed that the thermal degradation of CaCO3 followed the shrinkage geometrical spherical mechanism, R3 and the average activation energy was 224.6 kJ/mol. According to the results of the experimental design, the tryptophan concentration was the most influential variable affecting the relative fraction of vaterite in the produced crystals. It can be concluded that tryptophan is important for better understanding and controlling the polymorph, size, and morphology of CaCO3 crystals.

Using a Point-Line-Plane Representation for Unified Simulation of Planar and Spherical Mechanisms

This paper presents a geometric constraints driven approach to unified kinematic simulation of n-bar planar and spherical linkage mechanisms consisting of both revolute and prismatic joints. Generalized constraint equations using point, line, and plane coordinates have been proposed which unify simulation of planar and spherical linkages and are demonstrably scalable to spatial mechanisms. As opposed to some of the existing approaches, which seek to derive loop-closure equations for each type of mechanism separately, we have shown that the simulation can be made simpler and more efficient by using unified version of the geometric constraints on joints and links. This is facilitated using homogeneous coordinates and constraints on geometric primitives, such as point, line, and plane. Furthermore, the approach enables simpler programming, real-time computation, and ability to handle any type of planar and spherical mechanism. This work facilitates creation of practical and intuitive design tools for mechanism designers.

RESEARCH OF THE STRESS DISTRIBUTION IN THE HINGE ELEMENT OF THE LEADING RING OF A SPHERICAL TRANSFORMING MECHANISM

The article presents a theoretical study of the stress distribution of the leading links of the spherical transforming mechanism. Diagrams of the stress-strain state and stress fields in the leading element of a spherical mechanism are presented. Methods for improving the reliability and load capacity of the hinge drive shaft with the leading ring of the spherical mechanism are proposed.

FEATURES OF CHOOSING A ROLLING BEARING FOR A SPHERICAL TRANSFORMING MECHANISM

The article presents the rationale for choosing a rolling bearing for a spherical mechanism with two and three degrees of freedom. Calculation schemes for determining the direction and values of active forces are given. Recommendations are given for selecting a rolling bearing based on the forces acting on the mechanism elements.