scholarly journals Numerical Simulation Study on Environment-Friendly Floating Reef in Offshore Ecological Belt under Wave Action

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2257
Author(s):  
Yun Pan ◽  
Huanhuan Tong ◽  
Yang Zhou ◽  
Can Liu ◽  
Dawen Xue
Keyword(s):  
Numerical Simulation ◽  
Structural Design ◽  
Large Scale ◽  
Water Mass ◽  
Floating Body ◽  
The Finite Element Method ◽  
Lumped Mass ◽  
Environment Friendly ◽  
Ecological Corridor ◽  
New Type

An artificial floating reef is an important part of the coastal ecological corridor. The large-scale construction of floating reefs by optimizing mooring methods can effectively improve the ecological effects of coastal projects. The artificial floating reef belongs to coastal engineering, and wave resistance is fundamental to its structural design. In this paper, the method for processing coupling forces and motion, the method for judging the floating reef out of water surface, and the method for correcting velocity and acceleration of water mass points are elaborated in detail by using the finite element method and lumped-mass mooring model. By comparing and analyzing the results of physical experiment and numerical simulation, the correctness of the numerical model is verified. Finally, the diachronic variation of pitching angle of floating reef, the tension of the mooring rope, and the total tension of the fixed points of the fishing net were analyzed by the dynamic response numerical mode with a new type of mooring. The purpose of the current study was to provide a basis for the optimization of structure shape, the matching of floating body, and the counterweight of artificial floating reef.

scholarly journals Numerical Optimal Control for Problems with Random Forced SPDE Constraints

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
R. Naseri ◽  
A. Malek
Keyword(s):  
Numerical Simulation ◽  
Optimal Control ◽  
Large Scale ◽  
Polynomial Chaos ◽  
Optimization Problems ◽  
Hybrid Approach ◽  
Chaos Expansion ◽  
The Finite Element Method ◽  
Stochastic Diffusion Equation ◽  
Spatial Part

A numerical algorithm for solving optimization problems with stochastic diffusion equation as a constraint is proposed. First, separation of random and deterministic variables is done via Karhunen-Loeve expansion. Then, the problem is discretized, in spatial part, using the finite element method and the polynomial chaos expansion in the stochastic part of the problem. This process leads to the optimal control problem with a large scale system in its constraint. To overcome these difficulties the adjoint technique for derivative computation to implementation of the optimal control issue in preconditioned Newton’s conjugate gradient method is used. By some numerical simulation, it is shown that this hybrid approach is efficient and simple to implement.

A Fundamental Study on the Optimal Design of the Floating Tsunami Protection Wharf: About the Floating Body Length

2017 ◽  
Author(s):  
Mitsuhiro Masuda ◽  
Kiyokazu Minami ◽  
Koichi Masuda
Keyword(s):  
Numerical Simulation ◽  
Body Length ◽  
Large Scale ◽  
Mitigation Measures ◽  
Floating Body ◽  
Disaster Prevention ◽  
Mooring Lines ◽  
Fundamental Study ◽  
Tsunami Disaster ◽  
Floating Pier

On the vessels moored at the wharf, the situation such as drifting and wash up on the wharf due to the breaking of the mooring lines is occurred by the tsunami. The authors are clarified for applicability of the proposed floating tsunami protection wharf (FTPW). FTPW is the floating pier for tsunami disaster. The effect of FTPW is most promising as disaster prevention and mitigation measures for the moored vessels. The authors examined large scale FTPW until now. However, when floating body length was longer than a ship breadth, the possibility that disaster prevention performance of FTPW decreased was confirmed. In this study, the examination about the influence that floating body length gives in disaster prevention performance of FTPW is performed using numerical simulation. Therefore, in the range of length of FTPW/breadth of vessel = 1.0 to 8.0, it was confirmed that tsunami protection performance of FTPW was shown enough.

The study of the elastic deformation of a flexible wheel by a cam wave generator

2020 ◽  
Vol 65 (1) ◽  
pp. 51-58
Author(s):  
Sava Ianici
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Elastic Deformation ◽  
Theoretical Study ◽  
Elastic Field ◽  
The Finite Element Method ◽  
Elastic Deformations ◽  
Wave Generator ◽  
Two Stages

The paper presents the results of research on the study of the elastic deformation of a flexible wheel from a double harmonic transmission, under the action of a cam wave generator. Knowing exactly how the flexible wheel is deformed is important in correctly establishing the geometric parameters of the wheels teeth, allowing a better understanding and appreciation of the specific conditions of harmonic gearings in the two stages of the transmission. The veracity of the results of this theoretical study on the calculation of elastic deformations and displacements of points located on the average fiber of the flexible wheel was subsequently verified and confirmed by numerical simulation of the flexible wheel, in the elastic field, using the finite element method from SolidWorks Simulation.

scholarly journals Numerical and Experimental Study of Lightning Stroke to BIPV Modules

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 748
Author(s):  
Xiaoyan Bian ◽  
Yao Zhang ◽  
Qibin Zhou ◽  
Ting Cao ◽  
Bengang Wei
Keyword(s):  
Numerical Simulation ◽  
Experimental Study ◽  
Coupling Model ◽  
Maximum Temperature ◽  
Lightning Stroke ◽  
Study Results ◽  
Pv Modules ◽  
New Type ◽  
Metal Frame ◽  
Current Flows

Building Integrated Photovoltaic (BIPV) modules are a new type of photovoltaic (PV) modules that are widely used in distributed PV stations on the roof of buildings for power generation. Due to the high installation location, BIPV modules suffer from lightning hazard greatly. In order to evaluate the risk of lightning stroke and consequent damage to BIPV modules, the studies on the lightning attachment characteristics and the lightning energy withstand capability are conducted, respectively, based on numerical and experimental methods in this paper. In the study of lightning attachment characteristics, the numerical simulation results show that it is easier for the charges to concentrate on the upper edge of the BIPV metal frame. Therefore, the electric field strength at the upper edge is enhanced to emit upward leaders and attract the lightning downward leaders. The conclusion is verified through the long-gap discharge experiment in a high voltage lab. From the experimental study of multi-discharge in the lab, it is found that the lightning interception efficiency of the BIPV module is improved by 114% compared with the traditional PV modules. In the study of lightning energy withstand capability, a thermoelectric coupling model is established. With this model, the potential, current and temperature can be calculated in the multi-physical field numerical simulation. The results show that the maximum temperature of the metal frame increases by 16.07 °C when 100 kA lightning current flows through it and does not bring any damage to the PV modules. The numerical results have a good consistency with the experimental study results obtained from the 100 kA impulse current experiment in the lab.

Sublimation of composite ice and its influence on performance of ice shells

2021 ◽  
Vol 36 (1) ◽  
pp. 67-77
Author(s):  
Yue Wu ◽  
Junkai Huang ◽  
Jiafeng Chen
Keyword(s):  
Numerical Simulation ◽  
Shell Structure ◽  
Composite Shell ◽  
Engineering Practice ◽  
Sublimation Rate ◽  
Long Span ◽  
Static Performance ◽  
New Type ◽  
Ice Sublimation ◽  
Composite Shell Structure

The long-span ice composite shell structure is a new type of ice and snow structure developed in recent years. The engineering practice of ice composite shell shows that sublimation is one of the important reasons for its damage and even collapse. In this paper, we firstly supplemented the existing H-K equation and obtained the revised ice sublimation equation through indoor evaporative plate experiment considering the influence of admixtures and wind speed. Afterwards, combining the simulations of solar radiation and CFD, the numerical simulation of sublimation distribution on the surface of were realized by programming in Grasshopper platform. During sublimation, the thickness of the ice composite shell decreases by 0.38 mm every 10 days and the sublimation rate on the sunny side was 1.7 times that on the shady side. Finally, the static performance and stability of the sublimated ice composite spherical shell were analyzed. After 70 days of sublimation, the thickness of the ice composite shell structure becomes thinner and uneven, which leads its sensitivity to external load increases.

scholarly journals Fabrication of microcapsule extinguishing agent with core-shell structure for lithium-ions battery fire safety

2021 ◽  
Author(s):  
Weixin Zhang ◽  
Lin Wu ◽  
Dujin Qiao ◽  
Jie Tian ◽  
Yan Li ◽  
...  
Keyword(s):  
Large Scale ◽  
Urea Formaldehyde ◽  
Lithium Ion ◽  
Formaldehyde Resin ◽  
Shell Material ◽  
Lithium Ions ◽  
Safety Issues ◽  
Fire Extinguishing ◽  
New Type ◽  
Core Shell Structure

Safety issues limit the large-scale application of lithium-ion batteries. In this work, a new type of N-H-microcapsule fire extinguishing agent is prepared by using melamine-urea-formaldehyde resin as shell material, perfluoro(2-methyl-3-pentanone)...

scholarly journals Numerical Simulation of EPB Shield Tunnelling with TBM Operational Condition Control Using Coupled DEM–FDM

2021 ◽  
Vol 11 (6) ◽  
pp. 2551
Author(s):  
Hyobum Lee ◽  
Hangseok Choi ◽  
Soon-Wook Choi ◽  
Soo-Ho Chang ◽  
Tae-Ho Kang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Tunnel Boring Machine ◽  
Chamber Pressure ◽  
Screw Conveyor ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Operational Conditions ◽  
Shield Tunnelling ◽  
Epb Shield

This study demonstrates a three-dimensional numerical simulation of earth pressure balance (EPB) shield tunnelling using a coupled discrete element method (DEM) and a finite difference method (FDM). The analysis adopted the actual size of a spoke-type EPB shield tunnel boring machine (TBM) consisting of a cutter head with cutting tools, working chamber, screw conveyor, and shield. For the coupled model to reproduce the in situ ground condition, the ground formation was generated partially using the DEM (for the limited domain influenced by excavation), with the rest of the domain being composed of FDM grids. In the DEM domain, contact parameters of particles were calibrated via a series of large-scale triaxial test analyses. The model simulated tunnelling as the TBM operational conditions were controlled. The penetration rate and the rotational speed of the screw conveyor were automatically adjusted as the TBM advanced to prevent the generation of excessive or insufficient torque, thrust force, or chamber pressure. Accordingly, these parameters were maintained consistently around their set operational ranges during excavation. The simulation results show that the proposed numerical model based on DEM–FDM coupling could reasonably simulate EPB driving while considering the TBM operational conditions.

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