LNG Tank Sloshing Simulation of Multidegree Motions Based on Modified 3D MPS MethodRead the full article
Mathematical Problems in Engineering is a broad-based journal publishes results of rigorous engineering research across all disciplines, carried out using mathematical tools.
Chief Editor, Professor Guangming Xie, is currently a full professor of dynamics and control with the College of Engineering, Peking University. His research interests include complex system dynamics and control and intelligent and biomimetic robots.
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Experimental Testing and Numerical Modelling of Mechanical Behaviors of Silty Clay under Freezing-Thawing Cycles
Seasonal freezing-thawing cycle is one of the most common physical weathering processes in cold regions, which can significantly affect the mechanical behaviors of soil. In this paper, a series of freezing-thawing (F-T) cycle and consolidated drained triaxial tests have been carried out on silty clay samples collected from Tibetan Plateau. To do so, a modified numerical model was developed taking into F-T effect. Test results showed that the stress-strain curves of original soil specimens presented strain hardening characteristics, accompanied with shear shrinkage. In F-T experienced specimens, volumetric strain in triaxial loading stage was gradually increased, while failure strength was decreased. Elliptic and parabolic functions were selected in numerical modelling to describe volume and shear yield surfaces on a p-q plane, respectively. Moreover, a double-yield surface constitutive model was developed to describe relationships among deviatoric stress, axial strain, and volumetric strain. Furthermore, equations for model parameters with the number of F-T cycles as variable were derived based on the triaxial test results which were then substituted into the established model to take into account the effects of F-T cycles. Finally, numerical results were validated with experimental findings.
System Availability Modelling and Optimization considering Multigeneral Quality Characteristics
This paper analyzes the necessity that multigeneral quality characteristic parameters should be considered in availability modelling and optimization and then constructs an availability model including the indicators of reliability, maintainability, supportability, testability, and environmental factor. In the research process, it is assumed that the system has soft and hard failure mode, adopting mixed maintenance strategies, system delay time, and repair time, and test time are independent. On the basis of this, the single parameter, binary parameters, and multiparameters optimization were carried out with the maximum availability as the optimization function. Especially, the multiparameters availability optimization model in time dimension was designed based on particle swarm optimization. The design method was proved feasible through a numerical example, which can provide method support for the design and evaluation of general quality characteristic thresholds in the life cycle of a repairable system.
Cubic Spline Interpolation-Based Robot Path Planning Using a Chaotic Adaptive Particle Swarm Optimization Algorithm
This paper proposed a cubic spline interpolation-based path planning method to maintain the smoothness of moving the robot’s path. Several path nodes were selected as control points for cubic spline interpolation. A full path was formed by interpolating on the path of the starting point, control points, and target point. In this paper, a novel chaotic adaptive particle swarm optimization (CAPSO) algorithm has been proposed to optimize the control points in cubic spline interpolation. In order to improve the global search ability of the algorithm, the position updating equation of the particle swarm optimization (PSO) is modified by the beetle foraging strategy. Then, the trigonometric function is adopted for the adaptive adjustment of the control parameters for CAPSO to weigh global and local search capabilities. At the beginning of the algorithm, particles can explore better regions in the global scope with a larger speed step to improve the searchability of the algorithm. At the later stage of the search, particles do fine search around the extremum points to accelerate the convergence speed of the algorithm. The chaotic map is also used to replace the random parameter of the PSO to improve the diversity of particle swarm and maintain the original random characteristics. Since all chaotic maps are different, the performance of six benchmark functions was tested to choose the most suitable one. The CAPSO algorithm was tested for different number of control points and various obstacles. The simulation results verified the effectiveness of the proposed algorithm compared with other algorithms. And experiments proved the feasibility of the proposed model in different dynamic environments.
Analysis of the MHD Boundary Layer Flow over a Nonlinear Stretching Sheet in a Porous Medium Using Semianalytical Approaches
The purpose of the research is to inquire the outcomes of viscous and ohmic dissipation on the MHD flow in porous media in the region of suction and injection. A flow model of nonlinear ODEs with assisting boundary conditions is tackled with the help of computational software by using various standard techniques. The effects of relevant parameters on the concentration, thermal, and velocity distribution are illustrated graphically; also, the skin friction coefficient and flow rates of heat and mass transfer are calculated and shown in a tabular way. An analysis of the consequences proves that the flow field is effectively appreciable by injection and suction. Comparison with the already published work is made and found to be in good agreement.
Prediction of Mining Subsidence in Shallow Coal Seam
Theoretical calculation, numerical simulation, and field measurement were combined to study the recovery of coal resources in the 5th pan area of Dianping Coal Mine without damaging surface buildings. A mathematical model was established to predict the settlement range and displacement of the surface after coal mining. The FLAC3D5.0 program was used to simulate the evolution law of the overburden strata under the coal mining conditions of the study area. The lateral influence range was 45.8 m and 42.4 m, and the maximum surface subsidence was 2.604 m and 2.78 m, respectively. The mining boundary of the 5-210 working face was designed using the result of the simulation program. Real-time dynamic observation data collected from 18 surface displacement monitoring points measured surface subsidence as 2.69 m. The civil construction protection area was not deformed. The working face provided safe recovery of 1,471,446,000 kg of coal, resulting in significant economic and social benefits.
Coordinated Stability Control Strategy for Intelligent Electric Vehicles Using Vague Set Theory
Aiming at improving the tracking stability performance for intelligent electric vehicles, a novel stability coordinated control strategy based on preview characteristics is proposed in this paper. Firstly, the traditional stability control target is introduced with the two degrees of freedom model, which is realized by the sliding mode control strategy. Secondly, an auxiliary control target further amending the former one with the innovation formulation of the preview characteristics is established. At last, a multiple purpose Vague set leverages the contribution of the traditional target and the auxiliary preview target in various vehicle states. The proposed coordinated control strategy is analyzed on the MATLAB/CarSim simulation platform and verified on an intelligent electric vehicle established with A&D5435 rapid prototyping experiment platform. Simulation and experimental results indicate that the proposed control strategy based on preview characteristics can effectively improve the tracking stability performance of intelligent electric vehicles. In the double lane change simulation, the peak value of sideslip angle, yaw rate, and lateral acceleration of the vehicle is reduced by 13.2%, 11.4%, and 8.9% compared with traditional control strategy. The average deviations between the experimental and simulation results of yaw rate, lateral acceleration, and steering wheel angle are less than 10% at different speeds, which demonstrates the consistency between the experimental and the simulation results.