Journal of Mechanical Engineering, Automation and Control Systems
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Binary rat swarm optimizer algorithm for computing independent domination metric dimension problem
Get PDFIn this article, we look at the NP-hard problem of determining the minimum independent domination metric dimension of graphs. A vertex set B of a connected graph G(V,E) resolves G if every vertex of G is uniquely recognized by its vector of distances to the vertices in B. If there are no neighboring vertices in a resolving set B of G, then B is independent. Every vertex of G that does not belong to B must be a neighbor of at least one vertex in B for a resolving set to be dominant. The metric dimension of G, independent metric dimension of G, and independent dominant metric dimension of G are, respectively, the cardinality of the smallest resolving set of G, the minimal independent resolving set, and the minimal independent domination resolving set. We propose the first attempt to use a binary version of the Rat Swarm Optimizer Algorithm (BRSOA) to heuristically calculate the smallest independent dominant resolving set of graphs. The search agent of BRSOA are binary-encoded and used to identify which one of the vertices of the graph belongs to the independent domination resolving set. The feasibility is enforced by repairing search agent such that an additional vertex created from vertices of G is added to B, and this repairing process is repeated until B becomes the independent domination resolving set. Using theoretically computed graph findings and comparisons to competing methods, the proposed BRSOA is put to the test. BRSOA surpasses the binary Grey Wolf Optimizer (BGWO), the binary Particle Swarm Optimizer (BPSO), the binary Whale Optimizer (BWOA), the binary Gravitational Search Algorithm (BGSA), and the binary Moth-Flame Optimization (BMFO), according to computational results and their analysis
Mathematical simulation modeling analysis of sub-sea tunnel blasting based on grey correlation
No full textBlasting in the ocean tunnel has a great impact on Marine life and seabed vegetation, so it is necessary to control the impact of blasting vibration on the surrounding Marine environment. In this paper, taking Xiamen Tunnel as an example, the blasting vibration response characteristics of undersea tunnel are studied, and the velocity attenuation rules of tunnel structure in different directions are obtained. The grey correlation theory is innovatively applied to analyze the correlation degree of factors affecting the blasting vibration effect of the undersea tunnel, and the key factors and secondary factors affecting the blasting vibration effect of the tunnel are determined. The grey correlation theory is used to analyze the correlation degree between the blasting vibration effect of the cross-tunnel, which is conducive to improving the safety and stability of tunnel construction. It provides a new idea and method for vibration control of similar projects
Modal analysis and seismic optimization of multi-storey gymnasium frame
No full textIn order to improve the seismic resistance capacity of the multi-storey gymnasium frame, based on the finite element analysis method, the dynamic response characteristics were analyzed, and the natural frequencies and vibration modes were obtained. Based on the results of the modal analysis, different reinforcement methods were proposed for verification. Under the excitation conditions of Borego waves, the vibration responses of different nodes in initial model were obtained. Modal verification was carried out by using two methods of shear strengthening and support rod strengthening respectively. The analysis results show that the bearing capacity of the single-span frame is insufficient, the lateral stiffness is small, and it is prone to cause severe torsional vibration damage. It can also be known that the seismic resistance capacity of the support rods reinforcement is more balanced in different directions. It can not only effectively improve the lateral stiffness and bearing capacity of the structure, but also improve the seismic performance of the main structure through the energy dissipation of component yield, which is more suitable for multi-story buildings
Analysis of aerodynamic characteristics of drone wing based on CFD
No full textIn order to improve the aerodynamic characteristics of the drone wings, CFD method was used to simulate and calculate the lift coefficient, drag coefficient, and lift-drag ratio under different relative inflow velocities, as well as the velocity and pressure fields under different attack angles. Modal calculations were conducted on the wing to obtain the first four modal shapes, providing a basis for analyzing flutter characteristics. An iterative calculation method of incompressible potential flow-boundary layer based on surface element method was combined with the software XFOIL to optimize the airfoil at low wind speeds. The results indicate that the airfoil is susceptible to stall at high angles of attack, with the pressure of the separation flow being nearly equivalent to that at the separation point. Subsequent to separation, there is an increase in differential pressure resistance, resulting in a marked rise in the drag coefficient. At the optimized angle of attack, the lift-drag ratio of the optimized wing increases by 12.58 %, while there is a decrease of 0.084 % in lift coefficient and an increase of 11.21 % in drag coefficient
Research on stress through photoelastic experiment and finite element method considering sliding wear
Get PDFSliding contact on the contact interface of friction pairs is a common type of contact. The sliding wear caused by sliding contact has an obvious influence on the stress in the contact area. In this study, the photoelastic experiment and finite element method are adopted to study variation laws of stress in the contact area. The results show that the stress in the contact region is very concentrated, and the contact half-width gradually ascends with the increase of sliding wear. The stress intensity in the contact region and von Mises stress at the contact centre decrease with the increase of wear depth. In the case of a wear depth of less than 0.3 mm, the stress intensity and the contact stress decrease rapidly with the growth of wear depth. When the wear depth exceeds 0.3 mm, the influence of wear depth on the stress intensity and contact stress is small. The results of this research clarify the effect of sliding wear on the stress in the contact area, and provide a reference for studying the contact issues
Maintenance decision-making and its relevance in engineering asset management
Get PDFEngineering asset management (EAM) has received a lot of attention in the last few decades. Despite this, industries struggle to identify the best strategies for maintaining assets. The decision-making around selecting a relevant maintenance strategy generally considers factors like risk, performance and cost. Risk management is, usually, largely subjective and industries consequently make investments in a subjective manner, making the allocation of budget unstructured and arbitrary. Generally, industries focus only on either overt risks or basic performance of assets, thus creating uncertainties in the decision-making process. Recently, however, maintenance decision-making has evolved from a subjective assessment, chiefly dependent on expert opinions, to utilizing live-data-sensor technology. The attitude towards component failures and how to address them has changed drastically with the evolution of maintenance strategies. Additionally, the emergence and use of several tools and models have assisted the drafting and implementation of effective maintenance strategies. These advancements, however, have only considered discrete parameters while modelling, instead of using an integrated approach. One of the primary factors which can address this shortfall and make the decision-making process more robust is the economic element. To enable an effective decision-making process, it is imperative to consider quantifiable determinants and include economic parameters while drafting maintenance policies. This paper reviews maintenance decision-making strategies in EAM and also highlights its relevance through an economic lens
Influence of Copper-Iron (CuFe) and Copper-Tin (CuSN) alloys over mechanical strength properties in crimping process
Get PDFThis study investigates the comparative performance of Copper-Iron (CuFe) and Copper-Tin (CuSn) alloys in crimping processes, with a focus on their mechanical, electrical, and corrosion-resistance properties. Crimping is a critical method for creating reliable electrical and mechanical connections, particularly in environments subjected to significant mechanical stress and varying temperatures [1]. CuFe alloys, known for their superior mechanical strength and hardness, present challenges in crimping due to their increased resistivity and reduced ductility. Conversely, CuSn alloys offer a balance between electrical conductivity, ease of crimping, and corrosion resistance, making them a preferred choice in many industrial applications. This research aims to provide a comprehensive analysis of how the distinct properties of CuFe and CuSn alloys influence the crimping process, ultimately guiding material selection for optimized performance in various applications [2]. Experimental data will be drawn from tensile strength tests, electrical resistance measurements, and corrosion tests, providing a holistic understanding of the advantages and limitations of each alloy
Design and analysis of folding mechanism for automotive seats based on space maximization
Get PDFTo solve the problem of maximizing space utilization of car folding seats within limited spatial constraints, a design method for space-maximizing four-bar folding seat hinges is proposed. First, we will investigate the existing types of car folding seats, identify the mainstream configurations, and determine the optimal position of the four-bar linkage hinge point based on the constraints present within the car using theoretical analysis methods. Secondly, kinematic and dynamic models of the four-bar linkage mechanism are established, followed by the formulation of kinematic and dynamic equations. Finally, numerical methods are employed to solve these equations and obtain the kinematic and dynamic characteristics. The results indicate that the design method proposed in the article, which aims to maximize the space of the hinge four-bar folding seat, is efficient and feasible. This approach optimizes the utilization of interior space and enhances passenger comfort while accommodating the folding function of the seat within the existing vehicle environment. This method holds significant engineering implications for the design of folding seats in similar types of vehicles
A recent lower limb exoskeleton robot for gait rehabilitation: a review
Get PDFHuman rehabilitation improved significantly after traumas, surgery, or accidental cross-link events with human health. During the last six decades, exoskeletons have played a significant role in human activities related to body training and post-trauma or surgery treatment, especially in gait rehabilitation. The main goal of rehabilitation training is to restore patients’ physical abilities to average by improving and monitoring their posture and gaining weight. In this paper, a classification of various types of exoskeletons is provided, a comparison between the different lower limb exoskeletons for gait rehabilitation presents, the gait anatomy, mechanical design, and control strategy for the prototype of lower limb exoskeleton studies, and the end, some concluding remarks are stated that may be useful for future work. The paper concludes with conclusions and a significant reference list
Analysis of the force and power characteristics of a twin crank-type mechanism of an enhanced vibration exciter
Get PDFThe crank-type vibration exciters represent innovative and promising actuators for a variety of vibratory technological equipment. Extensive research has demonstrated their potential for generating specific trajectories of the working components of various technological machines. This study builds upon previous investigations of the authors, focusing on the kinematics and dynamics of crank-type vibration exciters, with a specific emphasis on analyzing the forces, moments, and torques acting on the elements of the twin crank-type actuating mechanism. The research methodology involves the development of a simplified dynamic diagram of the mechanism and derivation of the analytical expressions to describe its force parameters. Mathematical modeling and computer simulation are then conducted to analyze the forces, moments, and torques experienced by the mechanism during its motion under different operational conditions and design parameters. The results obtained provide time-dependent profiles of these parameters across various conditions and design configurations of the twin crank-type mechanism. A key scientific contribution of this paper consists in the development of the theoretical basis for creating novel techniques of dynamic and strength analysis and optimization of design and operational parameters of enhanced vibration exciters equipped with twin crank-type mechanisms. The research findings offer valuable insights for engineers involved in the development and enhancement of vibratory technological machines equipped with crank-type vibration exciters