Current Issue : October-December Volume : 2022 Issue Number : 4 Articles : 6 Articles
In view of the limitations of the mathematical method used in the container terminal logistics system, this paper uses Unity3D to establish a computer simulation model for the container automated yard, which dynamically displays the operation process of the container automated yard logistics system in real time. Through the plane four-parameter coordinate conversion method and by taking the Shanghai urban construction coordinate system as the medium, it completes the conversion from the satellite positioning reference ellipsoid coordinates to the three-dimensional virtual scene coordinates. The example results show that the method is reliable and practical, improves the accuracy and efficiency of positioning, and provides a reliable reference basis for the container terminal logistics system....
A general pneumatic soft gripper is proposed in this paper. Combined with the torque balance theory, the mathematical theoretical model of bending deformation of soft gripper is established based on Yeoh constitutive model and classical differential geometry. Assuming that the pressure in each inner cavity is evenly distributed, the input gas is in an ideal state, which is approximately treated as an isothermal condition, and all orifices experience blocked flow. In addition, compared with the mechanical work of gas, the energy related to gas flow and heat transfer is negligible. The nonlinear mechanical properties of silicone rubber are studied. It is regarded as isotropic and incompressible material, which is characterized by strain energy per unit volume. The material constant coefficients C10 and C20 are determined through the uniaxial tensile test, and the software gripper is simulated on the ABAQUS platform. The bending deformation models of grippers with three different force-bearing cavity structures are analyzed and compared, and the software clamping structure with the bending deformation most in line with the application conditions is selected. The limit input air pressure of the gripper and the situation of enveloping the clamping target object are analyzed. Through the bending deformation experiment, the maximum deformation angle is 72.4°. The relative error between the simulation analysis data and the prediction results of the mathematical model is no more than 3.5%, which verifies the effectiveness of the simulation and the correctness of the mathematical theoretical model of bending deformation. The soft manipulator proposed in this paper has good adaptability to grasping objects of different shapes and sizes. The minimum diameter of the target object that can be clamped is 0.1 mm. It can clamp the object weighing up to 1 kg. It has compact size, light weight, high ductility, and flexibility....
With the expansion of cyberspace and the increasing importance of users for privacy protection, anonymous network research has been further developed, especially for the numerous internet of things (IoT) devices. However, when we repeat the existing experiment in an anonymous network, there are many problems such as too old version, low realism, poor operability, and so on. In this paper, we analyzed the design requirements and topology of the new experimental platform. Two topologies with different levels of complexity are designed. We also set up a practical anonymous network simulation platform called LUNAR with virtualization, software-defined networking (SDN), and other technologies to solve those problems. The platform we proposed supports multiprotocol and reproducible complex networks with centralized management. Finally, we implement our simulation platform and reproduce two typical attacks, that is, time-linked Tor node reset attack and website fingerprint attacks on TheOnion Router (Tor) network, to evaluate the platform. Experiments results indicate the practicality and superiority of our simulation platform in terms of anonymous network simulation....
The calculation of wind load of high-rise buildings depends on the wind pressure distribution data and wind pressure coefficient on the outer surface of the building, but the actual wind pressure measurement of high-rise buildings is difficult to carry out. In order to obtain the effective wind pressure coefficient of the building and the application of the extended lattice Boltzmann method (LBM) in the wind resistance of high-rise buildings, in this paper, the wall-adapting local eddy (WALE) model, dynamic Smagorinsky model (DSM), and Smagorinsky model (SM) are embedded into LBM with multiple-relaxation-time (MRT) format. Three LBM large eddy simulation models, MRT-LBM-WALE, MRT-LBM-DSM, and MRT-LBM-SM, which can simulate the flow around a bluff body with high Rayleigh number, are constructed by using the subgrid eddy viscosity to modify the kinematic viscosity of LBM. Finally, the three turbulence models are used to simulate and analyze the three-dimensional steady wind flow field of a single high-rise building of the standard CAARC high-rise building model in the atmospheric boundary layer, and the numerical results are analyzed and compared with the wind tunnel test results. The results show that the numerical simulation better reflects the flow characteristics and surface wind pressure of the wind environment around the high-rise building. On the windward side, it fits well with the test results. On the crosswind side and leeward side, the numerical simulation results are between the NPL and TJ-2 test results. The windward side is subject to positive pressure, which is the highest at 2/3 of the height of the windward side and low on both sides and below. The leeward and crosswind surfaces of the building are all under negative pressure. The simulation results of the three turbulence models have little difference, which provides a basis for the study of the flow around the bluff body of high-rise buildings. It is proved that the numerical solutions of the three models are in good agreement with the experimental solutions, and the real subgrid eddy viscosity near the wall can be obtained, which can accurately predict the development of turbulent flow....
At present, the common cooking fume purification devices are mostly based on electrostatic technology. There are few researches on the microscopic process of coalescence and electric field parameters’ optimization. In this paper, COMSOL MultiphysicsTM was used to simulate the electrostatic coalescence of oil droplets in the coupling field of an electric field and flow field. The degree of deformation of oil droplets (D) and the starting coalescence time (tsc) were used to evaluate the coalescence process. The feasibility of the model was verified through experimental results. The effects of voltage, flow speed and oil droplet radius on tsc were investigated, and the parameters were optimized by the response surface method and Matrix correlation analysis. It can be concluded that increasing the voltage, flow speed and oil droplet radius appropriately would be conducive to the coalescence of oil droplets. When the oil droplet radius was in the range of 0–1.5 mm, it promoted the coalescence of oil droplets. The influence of various factors on oil droplet coalescence was flow speed > voltage > oil droplet radius. The optimal result obtained by simulation was that when the radius of the oil droplet was 1.56 mm, the voltage 12 kV and the flow speed 180 mm/ms, the shortest coalescence time of oil droplets was 16.8253 ms....
Metal additive manufacturing (AM) is a disruptive manufacturing technology that takes into account the needs of complex structural forming and highperformance component forming. At present, the understanding of metal additive manufacturing simulation methods is not thorough enough, which restricts the development of metal additive manufacturing. Present work discusses the evolution of KMC method simulation results for simulating metal additive manufacturing at different length ratios and different scanning speeds. The results reveal that as the scanning speed increases, the main grains in the simulation results are transformed from coarse columnar grains to crescent- shaped grains, which are in good agreement with the existing experimental results. Besides, as the ratio of unit physical length to unit simulation length increases, the ratio of unit physical time to unit simulation time gradually decreases....
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