A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves...A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves produced by an explosive source. These numerical results indicate that the code MMIC3D has the ability in computing cases such as 3D shock waves produced by air explosion, vortex region of the shock wave, the Mach wave, and reflected waves behind rigid boundaries.展开更多
Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the...Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.展开更多
When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by therm...When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.展开更多
The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic fi...The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.展开更多
This paper points out that a successful numerical simulation is to construct a correct conceptional model which is very dose to the natural condition. A new model, two dimensional coupled three dimensional model (2D -...This paper points out that a successful numerical simulation is to construct a correct conceptional model which is very dose to the natural condition. A new model, two dimensional coupled three dimensional model (2D -3D ) is presented in the Present paper,which is the most suitable one for the dual - structured - aquifer system. An example of Wenyinghu area is shown.By using the 2D-3D model, a satisfied result of the simulated area is achieved.展开更多
In this paper, we investigate the performance of the bulk fin field effect transistor (FinFET) through a three- dimensional (3D) full band Monte Carlo simulator with quantum correction. Several scattering mechanis...In this paper, we investigate the performance of the bulk fin field effect transistor (FinFET) through a three- dimensional (3D) full band Monte Carlo simulator with quantum correction. Several scattering mechanisms, such as the acoustic and optical phonon scattering, the ionized impurity scattering, the impact ionization scattering and the surface roughness scattering are considered in our simulator. The effects of the substrate bias and the surface roughness scattering near the Si/SiO2 interface on the performance of bulk FinFET are mainly discussed in our work. Our results show that the on-current of bulk FinFET is sensitive to the surface roughness and that we can reduce the substrate leakage current by modulating the substrate bias voltage.展开更多
How to solve the coupling relations in a 6 - DOF parallel robot quickly and accurately within the limits of realtime control is a critical problem. In traditional analytic method, the complicated mathemtical model mus...How to solve the coupling relations in a 6 - DOF parallel robot quickly and accurately within the limits of realtime control is a critical problem. In traditional analytic method, the complicated mathemtical model must first be constructed and then solved by programming.Obviously, this method is not very practical. This paper,therefore, proposes a new way of approach with a new method using 3- D animation for the solving of coupling relations in the 6 - DOF parallel robot. This method is much simpler and its solving accuracy approaches that of the more complicated analytic method.展开更多
The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse colu...The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse column on the outside of working face has been a difficult problem. Based on this, numerical simulation and imaging research were carried out in this paper. The results indicate that when a seismic source near the roadway is excited, a part of seismic wave propagates along the roadway direction, namely direct P-wave, direct S-wave and direct Love channel wave.<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">When the body waves and Love channel wave propagating to the outside</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of working face meet the interface of collapse column, the reflected Love channel wave and reflected body waves are generated.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Reflection </span><span style="font-family:Verdana;">body </span><span style="font-family:Verdana;">waves and direct waves are mixed in time domain, which is difficult to identify in seismic records, while reflected Love channel wave whose amplitude is relatively strong. The </span><span style="font-family:Verdana;">reflected </span><span style="font-family:Verdana;">Love channel wave which has a large interval from other wave trains in the time domain is easily recognizable in seismic record,</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">which</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">makes it suitable for advanced detection of collapse column. The signal-to-noise ratio of X component is higher than that of Y component and Z component. According to the seismic records, polarization filtering was carried out to enhance the effective wave, which removed the interference waves, and the signal was migrated to get the position parameters of collapse column interface, which was basically consistent with the model position.</span>展开更多
The radial ultrasonic rolling electrochemical micromachining(RUR-EMM)combined rolling electrochemical micromachining(R-EMM)and ultrasonic vibration was studied in this paper.The fundamental understanding of the machin...The radial ultrasonic rolling electrochemical micromachining(RUR-EMM)combined rolling electrochemical micromachining(R-EMM)and ultrasonic vibration was studied in this paper.The fundamental understanding of the machining process especially the interaction between multiphysics in the interelectrode gap(IEG)was investigated and discussed by the finite element method.The multiphysics coupling model including flow field model,Joule heating model,material dissolution model and vibration model was built.3D multiphysics simulation based on micro dimples process in RUR-EMM and R-EMM was proposed.Simulation results showed that the electrolyte flowed into and out IEG periodically,gas bubbles were easy to squeeze out and the gas void fraction deceased about 16%to 54%,the maximum current density increased by 1.36 times in RUR-EMM than in R-EMM in one vibration period of time.And application of the ultrasonic vibration increased the electrolyte temperature about 1.3–4.4%in IEG.Verification experiments of the micro dimple process denoted better corrosion consistency of array dimples in RUR-EMM,there was no island at the micro dimple bottom which always formed in R-EMM,and an aggregated deviation of less than 8.7%for the micro dimple depth and 4%for the material removal amount between theory and experiment was obtained.展开更多
Viscous heating has a substantial influence on the extrusion forming process and product quality of powder materials.This study selected the MUZL420 ring die pellet mill as the research object,from which a 3D flow phy...Viscous heating has a substantial influence on the extrusion forming process and product quality of powder materials.This study selected the MUZL420 ring die pellet mill as the research object,from which a 3D flow physical model was established.The numerical simulation of 3D nonisothermal flow in the extrusion pelletizing process of granulated alfalfa was performed with POLYFLOW.The distribution laws of pressure,velocity,shear rate,viscosity,viscous heating and temperature in the flow field were revealed to thoroughly investigate the pelletizing process and provide a reference for structural optimization and process control.The results showed that two extrusion zones in the pelleting chamber were symmetrical with respect to the center,and the significant pressure gradient along the rotating direction of the ring die and the roller caused the material to flow back in the opposite direction.There were larger velocity gradients,shear rates and viscous heating levels in the deformation and compaction zone,the negative pressure zone behind the extrusion zone and the die holes.The distribution of viscosity was opposite to that of the shear rate.The temperature increase area caused by viscous heating gradually expanded from the material inlet to the bottom of the extrusion chamber along the Z-axis direction,and the temperature increased accordingly.The extrusion force and the forming temperature in the extrusion forming zone were captured in the numerical simulation.The extrusion forming density was calculated with the regression prediction model established through the simulation experiment of pelletizing with a ring die.Through a comparison with the results of mean alfalfa pellet density from the ring die pellet mill experiment,the relative error was less than 5%,which indicated that the numerical simulation method was reliable.展开更多
This article deals with generation and application of three-dimensional (3D) atmospheric turbulence field in large aircraft real-time flight simulation. The modeling requirements for the turbulence field of large airc...This article deals with generation and application of three-dimensional (3D) atmospheric turbulence field in large aircraft real-time flight simulation. The modeling requirements for the turbulence field of large aircraft flight simulation are analyzed here. The spatial turbulence field is generated in the frequency domain by using the Monte Carlo method,and then transformed back to the time domain with the 3D inverse Fourier transform. The von Karman model is adopted for an accurate description of the turb...展开更多
The InjectorⅡ, one of the two parallel injectors of the high-current superconducting proton driver linac for the China Accelerator-Driven System (C-ADS) project, is being designed and constructed by the Institute o...The InjectorⅡ, one of the two parallel injectors of the high-current superconducting proton driver linac for the China Accelerator-Driven System (C-ADS) project, is being designed and constructed by the Institute of Modern Physics. At present, the design work for the injector is almost finished. End-to-end simulation has been carried out using the TRACK multiparticle simulation code to check the match between each acceleration section and the performance of the injector as a whole. Moreover, multiparticle simulations with all kinds of errors and misalignments have been performed to define the requirements of each device. The simulation results indicate that the lattice design is robust. In this paper, the results of end-to-end simulation and error simulation with a 3-D field map are presented.展开更多
基金ACKNOWLEDGMENTS The work was supported by the National Nature Science Foundation of China (Nos.11161002 and 41001320), Natural Science Foundation of Jiangxi province (No.20114BAB201016). Thanks for the useful advices of the editors and the reviewers.
文摘A numerical method is presented that simulates 3D explosive field problems. A code MMIC3D using this method can be used to simulate the propagation and reflected effects of all kinds of rigid boundaries to shock waves produced by an explosive source. These numerical results indicate that the code MMIC3D has the ability in computing cases such as 3D shock waves produced by air explosion, vortex region of the shock wave, the Mach wave, and reflected waves behind rigid boundaries.
基金National Natural Science Foundation of China(Grant No.49236120)
文摘Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.
文摘When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.
文摘The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.
文摘This paper points out that a successful numerical simulation is to construct a correct conceptional model which is very dose to the natural condition. A new model, two dimensional coupled three dimensional model (2D -3D ) is presented in the Present paper,which is the most suitable one for the dual - structured - aquifer system. An example of Wenyinghu area is shown.By using the 2D-3D model, a satisfied result of the simulated area is achieved.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CBA00604)
文摘In this paper, we investigate the performance of the bulk fin field effect transistor (FinFET) through a three- dimensional (3D) full band Monte Carlo simulator with quantum correction. Several scattering mechanisms, such as the acoustic and optical phonon scattering, the ionized impurity scattering, the impact ionization scattering and the surface roughness scattering are considered in our simulator. The effects of the substrate bias and the surface roughness scattering near the Si/SiO2 interface on the performance of bulk FinFET are mainly discussed in our work. Our results show that the on-current of bulk FinFET is sensitive to the surface roughness and that we can reduce the substrate leakage current by modulating the substrate bias voltage.
文摘How to solve the coupling relations in a 6 - DOF parallel robot quickly and accurately within the limits of realtime control is a critical problem. In traditional analytic method, the complicated mathemtical model must first be constructed and then solved by programming.Obviously, this method is not very practical. This paper,therefore, proposes a new way of approach with a new method using 3- D animation for the solving of coupling relations in the 6 - DOF parallel robot. This method is much simpler and its solving accuracy approaches that of the more complicated analytic method.
文摘The safety accidents caused by collapse column water diversion occur frequently, which has great hidden danger to the safety production of coal mine. Limited by the space of underground, the detection of collapse column on the outside of working face has been a difficult problem. Based on this, numerical simulation and imaging research were carried out in this paper. The results indicate that when a seismic source near the roadway is excited, a part of seismic wave propagates along the roadway direction, namely direct P-wave, direct S-wave and direct Love channel wave.<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">When the body waves and Love channel wave propagating to the outside</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">of working face meet the interface of collapse column, the reflected Love channel wave and reflected body waves are generated.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Reflection </span><span style="font-family:Verdana;">body </span><span style="font-family:Verdana;">waves and direct waves are mixed in time domain, which is difficult to identify in seismic records, while reflected Love channel wave whose amplitude is relatively strong. The </span><span style="font-family:Verdana;">reflected </span><span style="font-family:Verdana;">Love channel wave which has a large interval from other wave trains in the time domain is easily recognizable in seismic record,</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">which</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">makes it suitable for advanced detection of collapse column. The signal-to-noise ratio of X component is higher than that of Y component and Z component. According to the seismic records, polarization filtering was carried out to enhance the effective wave, which removed the interference waves, and the signal was migrated to get the position parameters of collapse column interface, which was basically consistent with the model position.</span>
基金financial support of the projects from the National Natural Science Foundation of China(Nos.51975532 and 51475428)the Zhejiang Provincial Natural Science Foundation(No.LY19E050007)。
文摘The radial ultrasonic rolling electrochemical micromachining(RUR-EMM)combined rolling electrochemical micromachining(R-EMM)and ultrasonic vibration was studied in this paper.The fundamental understanding of the machining process especially the interaction between multiphysics in the interelectrode gap(IEG)was investigated and discussed by the finite element method.The multiphysics coupling model including flow field model,Joule heating model,material dissolution model and vibration model was built.3D multiphysics simulation based on micro dimples process in RUR-EMM and R-EMM was proposed.Simulation results showed that the electrolyte flowed into and out IEG periodically,gas bubbles were easy to squeeze out and the gas void fraction deceased about 16%to 54%,the maximum current density increased by 1.36 times in RUR-EMM than in R-EMM in one vibration period of time.And application of the ultrasonic vibration increased the electrolyte temperature about 1.3–4.4%in IEG.Verification experiments of the micro dimple process denoted better corrosion consistency of array dimples in RUR-EMM,there was no island at the micro dimple bottom which always formed in R-EMM,and an aggregated deviation of less than 8.7%for the micro dimple depth and 4%for the material removal amount between theory and experiment was obtained.
基金funded by the National Natural Science Foundation of China(NSFC)(51365002)the Gansu Agricultural University Youth Tutor Foundation(GAUQNDS-201204).
文摘Viscous heating has a substantial influence on the extrusion forming process and product quality of powder materials.This study selected the MUZL420 ring die pellet mill as the research object,from which a 3D flow physical model was established.The numerical simulation of 3D nonisothermal flow in the extrusion pelletizing process of granulated alfalfa was performed with POLYFLOW.The distribution laws of pressure,velocity,shear rate,viscosity,viscous heating and temperature in the flow field were revealed to thoroughly investigate the pelletizing process and provide a reference for structural optimization and process control.The results showed that two extrusion zones in the pelleting chamber were symmetrical with respect to the center,and the significant pressure gradient along the rotating direction of the ring die and the roller caused the material to flow back in the opposite direction.There were larger velocity gradients,shear rates and viscous heating levels in the deformation and compaction zone,the negative pressure zone behind the extrusion zone and the die holes.The distribution of viscosity was opposite to that of the shear rate.The temperature increase area caused by viscous heating gradually expanded from the material inlet to the bottom of the extrusion chamber along the Z-axis direction,and the temperature increased accordingly.The extrusion force and the forming temperature in the extrusion forming zone were captured in the numerical simulation.The extrusion forming density was calculated with the regression prediction model established through the simulation experiment of pelletizing with a ring die.Through a comparison with the results of mean alfalfa pellet density from the ring die pellet mill experiment,the relative error was less than 5%,which indicated that the numerical simulation method was reliable.
文摘This article deals with generation and application of three-dimensional (3D) atmospheric turbulence field in large aircraft real-time flight simulation. The modeling requirements for the turbulence field of large aircraft flight simulation are analyzed here. The spatial turbulence field is generated in the frequency domain by using the Monte Carlo method,and then transformed back to the time domain with the 3D inverse Fourier transform. The von Karman model is adopted for an accurate description of the turb...
基金Supported by National Natural Science Foundation of China (91026001)
文摘The InjectorⅡ, one of the two parallel injectors of the high-current superconducting proton driver linac for the China Accelerator-Driven System (C-ADS) project, is being designed and constructed by the Institute of Modern Physics. At present, the design work for the injector is almost finished. End-to-end simulation has been carried out using the TRACK multiparticle simulation code to check the match between each acceleration section and the performance of the injector as a whole. Moreover, multiparticle simulations with all kinds of errors and misalignments have been performed to define the requirements of each device. The simulation results indicate that the lattice design is robust. In this paper, the results of end-to-end simulation and error simulation with a 3-D field map are presented.