Numerical simulation is described which estimates the performance of thulium sensitized holmium doped CW fluoride fiber laser at 2.04 μm for both core and cladding pumped. This model takes into account the mechanis...Numerical simulation is described which estimates the performance of thulium sensitized holmium doped CW fluoride fiber laser at 2.04 μm for both core and cladding pumped. This model takes into account the mechanisms of cross relaxation and energy transfer to describe the laser operation. A subroutine program for calculating the absorption rate of cladding pumped scheme is included in the model. The losses of signal and pump light along the fiber have been taken into account. The test of cladding pumped scheme program shows good agreement with the experimental result. The experimental results of core pumping Tm Ho doped fiber laser in fluoride host are compared with the present model, and shows a good agreement with calculations. This model also provides data of the optimum parameters for the configuration of the efficient cladding pumped Tm Ho fluoride laser systems.展开更多
Numerical simulation of oil migration and accumulation is to describe the history of oil migration and accumulation in basin evolution. It is of great value in the exploration oil resources and their rational evaluati...Numerical simulation of oil migration and accumulation is to describe the history of oil migration and accumulation in basin evolution. It is of great value in the exploration oil resources and their rational evaluation. This paper, puts forward the mathematical model and the modified method of alternating direction implicit interactive scheme. For the famous hydraulic experiment of secondary migration_accumulation (cut plane and plane problem), it has been done the numerical simulation test, and both the computational and experimental results are identical.展开更多
By considering the heterogeneity of geomechanical materials, the source development of earthquake under compression boundary conditions is studied with a newly developed numerical method, Rock Failure Process Analysis...By considering the heterogeneity of geomechanical materials, the source development of earthquake under compression boundary conditions is studied with a newly developed numerical method, Rock Failure Process Analysis code (RFPA2D). The process of fault forming and associated micro seismicities in a rectangle area with a inclusion but without any clear structural features of original fault is modeled. The modeling demonstrates the whole process of source development of earthquake from deformation, micro failure to collapse and the behavior of temporal spatial distribution of micro seismicities. The stress, strain and the temporal spatial distribution of micro seismicities vividly depict the phenomena of localization, temporal transitions, dilatation or rise, elastic rebound and conjugate (X type) deformation zone.展开更多
In this paper, a 5-level spectral AGCM is used to examine the sensitivity of simulated East Asian summer monsoon circulation and rainfall to cumulus parameterization schemes. From the simulated results of East Asian ...In this paper, a 5-level spectral AGCM is used to examine the sensitivity of simulated East Asian summer monsoon circulation and rainfall to cumulus parameterization schemes. From the simulated results of East Asian monsoon circulations and rainfalls during the summers of 1987 and 1995, it is shown that the Kuo′s convective parameterization scheme is more suitable for the numerical simulation of East Asian summer monsoon rainfall and circulation. This may be due to that the cumulus in the rainfall system is not strong in the East Asian monsoon region.展开更多
The reliability of the numerical K ε model for determining wind pressure on building surfaces is evaluated. The solution algorithm is based on a body fitted non orthogonal curvilinear coordinate system and a st...The reliability of the numerical K ε model for determining wind pressure on building surfaces is evaluated. The solution algorithm is based on a body fitted non orthogonal curvilinear coordinate system and a staggered grid arrangement. The covariant velocity components are chosen as dependent variables. Convective fluxes are described by the Power Law Scheme. The grids are generated with an elliptic grid generator using control functions. The results compare favorably with those by Oxford wind tunnel measurements.展开更多
A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic mo...A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic model. The hydrostatic approximation was abandoned and the simple energy ( E e ) closure scheme was used in both models. Using the two models, characteristics of PBL structure and its evolution were fully studied. The main characteristic of the PBL is the circulation, and it fairly affects the distribution of the pollutant in the pit.展开更多
According to the precursory data of the 1976 Tangshan earthquake( M =7.8), and combining with the research results of rock fracture, seismic source, tectonics, seismic precursors, dynamic condition and crust structu...According to the precursory data of the 1976 Tangshan earthquake( M =7.8), and combining with the research results of rock fracture, seismic source, tectonics, seismic precursors, dynamic condition and crust structure, the seismogenic process of Tangshan earthquake has been numerically simulated by using the model of water saturated porous medium with a rhombic hard inclusion. First, a system of seismogenic dynamics equations of solid liquid two phase medium has been set up under considering rock inelastic dilation, strain softening and pore water permeation. Then, the finite difference method to solve the equation system in incremental form has been presented. Finally, the seismogenic process of Tangshan earthquake and the temporal spatial characteristics of its precursors have been numerically simulated when the hard inclusion includes a soft fault belt. The numerically simulating result shows that the development of Tangshan earthquake mainly undergoes following processes: elastic accumulation, early inelastic cubic dilation, accelerative softening (failure and creep) of fault first time, inelastic dilation twice in Tianjin—Ninghe area, accelerative softening of fault twice and instability. Corresponding to the fault accelerative softening, elastic recovery and inelastic dilation twice in some parts of seismogenic medium. By comparing with the data of precursory observation, ones can find the preceding simulating result explains the varied characters of practical data better. Meanwhile, the numerical simulation further displays the temporal spatial change law and complex patterns of the field of Tangshan earthquake development as well. It makes a base study for the physical mechanism of change of the seismic precursory field.展开更多
In this paper,the Pennsylvania State University-NCAR Mesoscale Model (MM4)is used to investigate the explosive oceanic cyclone of 14-15 March 1988 over the warm Kuroshio Current. A series of numerical simulations on ...In this paper,the Pennsylvania State University-NCAR Mesoscale Model (MM4)is used to investigate the explosive oceanic cyclone of 14-15 March 1988 over the warm Kuroshio Current. A series of numerical simulations on this cyclogenesis indicates that the favorable weather conditions and strong baroclinity in the low- and middle-level are essential to its explosive development. The explosive cyclogenesis occurred over a wide range of sea surface temperatures (SST′s),which was then characterized by strong baroclinity,the low-level jet (LLJ) was initially formed under the favorable atmospheric circulation and then this LLJ advected the moisture and heat northward for the explosive development of the cyclone,the LLJ played an important role in the process of cyclogenesis.Sensitivity experiments show that the latent heating was a key factor to explosive cyclogenesis,the latent heating deepened the short-wave trough,which resulted in the rapid intensification of the cyclone; while in the explosive intensification stage and continuous development stage, there was less contribution of local surface processes for the explosion of the cyclone.展开更多
The distributive law of flow rate is studiedfor highly viscoelastic flow in threedimensional slit channel with varying thickness by using Finite Block Element Method(FBM).As an example.the influence of restrictive blo...The distributive law of flow rate is studiedfor highly viscoelastic flow in threedimensional slit channel with varying thickness by using Finite Block Element Method(FBM).As an example.the influence of restrictive block on.flow rate is obtained in fish channel of the plate extruding die and the results of numerical simulation are in concordance withthe approximatical analytical solution.It is proved that FBM can be considered as an important toolfor CAD/CAM.展开更多
The latest progress on the study of numerical simulation of mold filling and solidification process of shaped casting is reviewed. In mold filling process simulation of castings, the SOLA VOF algorithmis is improve...The latest progress on the study of numerical simulation of mold filling and solidification process of shaped casting is reviewed. In mold filling process simulation of castings, the SOLA VOF algorithmis is improved in efficient free surface treatment and turbulence consideration, and parallel computational techniques are implemented to accelerate the fluid flow calculation time as well. Methods for predication of shrinkage defects of steel castings and S G. iron castings are developed based on the solidification simulation. In order to reduce the residual stress and deformation of castings, a combined FDM/FEM method is implemented for the modelling of stresses. Numerical models for the simulation of micro structure and prediction of mechanical properties of S G. iron are developed. The verifications and applications of the simulation software show that the models and techniques adopted in current research work are efficient and appropriate for the numerical simulation of shaped castings.展开更多
Based on a simplified media model of Gonghe area, the precursor characteristics of Gonghe M 7.0 earthquake in 1990 are simulated in this paper by using the constitutive relationship of binary medium (solid and wate...Based on a simplified media model of Gonghe area, the precursor characteristics of Gonghe M 7.0 earthquake in 1990 are simulated in this paper by using the constitutive relationship of binary medium (solid and water). The results show that the simulated state distribution and extension variation of media are identical with the spatial and temporal distribution of reliable anomalies before Gonghe earthquake. The study also suggests that the development of the Gonghe earthquake has experienced a series of processes such as elastic deformation of large scale, early nonelastic dilatation, strain softening and elastic recovery in the neighbour region of Xining, nonelasscale, early nonelastic dilatation, strain softening and elastic recovery in the neighbour region of nonelastic dilatation of high dense block near seismic source and earthquake occurrence. Therefore, it can be concluded that this earthquake development is neither a simple process for fissures developing and linking up with one another, nor a process of nonelastic volume expanion and water flowing into medium around seismic source, conrary, it is a complicated medium saate changing process, and the style of such changing depends on geological structure environment of seismic source and its neighbour region. It is considered that different earthquakes are accompanied by different geological conditions, the spatial and temporal behavior of their precusors are certainly different.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized...Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere was established through numerical simulation,and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting was investigated.The simulation results indicate that when the coal injection rate decreased from 36 to 30t/h and the hydrogen injection increased from 0 to 3600 m^(3)/h,the CO_(2)emissions decreased from 1860 to 1551 kg/t,which represents a16.6%reduction,and the pulverized coal burnout decreased from 70.1%to 63.7%.The heat released from hydrogen combustion can not only promote the volatilization of pulverized coal but also affect the combustion reaction between volatilization and oxygen,which resulted in a decrease in the temperature at the end of the raceway.Co-injection of hydrogen with PCI increased the wall temperature near the upper half part of the raceway and at the outlet of the tuyere,which required a high cooling efficiency to extend the service life of the blast furnace.The increase in oxygen level compensated for the decreased average temperature in the raceway due to hydrogen injection.The increase in the oxygen content by 3%while maintaining constant hydrogen and PCI injection rates increased the burnout and average raceway temperature by 4.2%and 43 K,respectively.The mole fraction of CO and H_(2) production increased by 0.04 and 0.02,respectively.Burnout can be improved through optimization of the particle size distribution of pulverized coal.展开更多
Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthqu...Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.展开更多
The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to ...The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to achieving controllable stress-strain rate loading.In this study,we have,for the first time,combined one-dimensional fluid computational software with machine learning methods.We first elucidated the mechanisms by which GDI structures control stress and strain rates.Subsequently,we constructed a machine learning model to create a structure-property response surface.The results show that altering the loading velocity and interlayer thickness has a pronounced regulatory effect on stress and strain rates.In contrast,the impedance distribution index and target thickness have less significant effects on stress regulation,although there is a matching relationship between target thickness and interlayer thickness.Compared with traditional design methods,the machine learning approach offers a10^(4)—10^(5)times increase in efficiency and the potential to achieve a global optimum,holding promise for guiding the design of GDI.展开更多
To further reduce the explosive thickness and to improve the bonding quality of titanium/steel composite plates,explosive welding experiments of TA1/Q235 were conducted using a low detonation velocity explosive(53#)un...To further reduce the explosive thickness and to improve the bonding quality of titanium/steel composite plates,explosive welding experiments of TA1/Q235 were conducted using a low detonation velocity explosive(53#)under the guidance of the explosive welding lower limit principle with the flyer plate thicknesses of 1,2,and 4 mm and gaps of 3,6,and 8 mm.The weldability window for titanium/steel explosive welding was calculated,and a quantitative relationship between dynamic and static process parameters was developed.Aβ-V_(p) high-speed inclined collision model was proposed,and two-dimensional numerical simulations for the explosive welding tests were performed using the smoothed particle hydrodynamics(SPH)algorithm,revealing the growth evolution mechanisms of the typical waveform morphology characteristics.Through microstructural characterization techniques,such as optical microscope,scanning electron microscope,energy dispersive spectrometer,and electron backscattered diffractometer,and mechanical property tests in terms of shear strength,bending performance,and impact toughness,the microstructure and mechanical properties of the interfaces of explosively welded TA1/Q235 composite plates were investigated.Results show that the quality of interface bonding is excellent,presenting typical waveform morphology with an average interface shear strength above 330 MPa and an average impact toughness exceeding 81 J.All samples can be bent to 180°without significant delamination or cracking defects.展开更多
A suction casting experiment was conducted on Zr_(55)Cu_(30)Al_(10)Ni_(5)(at%)amorphous alloy.Using ProCAST software,numerical simulations were performed to analyze the filling and solidification processes.The velocit...A suction casting experiment was conducted on Zr_(55)Cu_(30)Al_(10)Ni_(5)(at%)amorphous alloy.Using ProCAST software,numerical simulations were performed to analyze the filling and solidification processes.The velocity field during the filling process and the temperature field during the solidification process of the alloy melt under different process parameters were obtained.Based on the simulation results,a Zr-based amorphous alloy micro-gear was prepared via casting.The results indicate that increasing the suction casting temperature enhances the fluidity of alloy melt but induces unstable flow rate during filling,which is detrimental to complete filling.Zr-based amorphous micro-gears with a module of 0.6 mm,a tooth top diameter of 8 mm,and 10 teeth were prepared through the suction casting.X-ray diffraction and differential scanning calorimetry analyses confirm that the fabricated micro-gear exhibits characteristic amorphous structural features,demonstrating well-defined geometrical contours and satisfactory forming completeness.展开更多
We proposed a new technique route of directional solidification for the manufacture of super slab.A 7-t laboratory-scale thick slab was casted and characterised for trial.To further understand the process,the evolutio...We proposed a new technique route of directional solidification for the manufacture of super slab.A 7-t laboratory-scale thick slab was casted and characterised for trial.To further understand the process,the evolution of the multiple physical fields during the directional solidification was simulated and verified.Similar to the convectional ingot casting,a negative segregated cone of equiaxed grains was formed at the bottom,and a seriously positive segregated region was formed beneath the top surface of the slab.Specific measures on the lateral walls,base plate,and free surface were strongly recommended to ensure that the slab is relatively directionally casted.A water-cooling copper base plate accelerates the solidification rate and the columnar growth along the vertical direction.It inhibits the sedimentation of equiaxed grains and enlarges the columnar zone.Based on the simulation analysis,it can be concluded that the directional solidification technique route is promising to manufacture super slab with lower segregation level,and less porosities and inclusions.展开更多
As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-s...As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.展开更多
To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite,a multi-perspective approach was adopted.This approach combined triaxial compression tests,acousti...To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite,a multi-perspective approach was adopted.This approach combined triaxial compression tests,acoustic emission(AE)monitoring,and PFC simulations.The results show that:1)Confining pressure exhibits a pronounced linear correlation with both yield strength and compressive strength.The enhancement of confining pressure significantly improves the deformability of granite and promotes a progressive shift in failure mechanism from brittle rupture to ductile deformation;2)Increasing confining pressure elevates the stress threshold for microcrack initiation and suppresses crack propagation.As a result,the proportion of shear cracks increases(based on AE analysis)from 18.71%to 61.2%,marking a transition in the dominant failure mode from tensile to shear;3)Confining pressure facilitates the development of grain boundary shear cracks(GBSCs),establishing the primary damage pathways.In addition,local stress concentrations under high confinement conditions trigger intragranular cracking.This highlights the regulatory effect of confining pressure on microcrack evolution.展开更多
文摘Numerical simulation is described which estimates the performance of thulium sensitized holmium doped CW fluoride fiber laser at 2.04 μm for both core and cladding pumped. This model takes into account the mechanisms of cross relaxation and energy transfer to describe the laser operation. A subroutine program for calculating the absorption rate of cladding pumped scheme is included in the model. The losses of signal and pump light along the fiber have been taken into account. The test of cladding pumped scheme program shows good agreement with the experimental result. The experimental results of core pumping Tm Ho doped fiber laser in fluoride host are compared with the present model, and shows a good agreement with calculations. This model also provides data of the optimum parameters for the configuration of the efficient cladding pumped Tm Ho fluoride laser systems.
文摘Numerical simulation of oil migration and accumulation is to describe the history of oil migration and accumulation in basin evolution. It is of great value in the exploration oil resources and their rational evaluation. This paper, puts forward the mathematical model and the modified method of alternating direction implicit interactive scheme. For the famous hydraulic experiment of secondary migration_accumulation (cut plane and plane problem), it has been done the numerical simulation test, and both the computational and experimental results are identical.
文摘By considering the heterogeneity of geomechanical materials, the source development of earthquake under compression boundary conditions is studied with a newly developed numerical method, Rock Failure Process Analysis code (RFPA2D). The process of fault forming and associated micro seismicities in a rectangle area with a inclusion but without any clear structural features of original fault is modeled. The modeling demonstrates the whole process of source development of earthquake from deformation, micro failure to collapse and the behavior of temporal spatial distribution of micro seismicities. The stress, strain and the temporal spatial distribution of micro seismicities vividly depict the phenomena of localization, temporal transitions, dilatation or rise, elastic rebound and conjugate (X type) deformation zone.
文摘In this paper, a 5-level spectral AGCM is used to examine the sensitivity of simulated East Asian summer monsoon circulation and rainfall to cumulus parameterization schemes. From the simulated results of East Asian monsoon circulations and rainfalls during the summers of 1987 and 1995, it is shown that the Kuo′s convective parameterization scheme is more suitable for the numerical simulation of East Asian summer monsoon rainfall and circulation. This may be due to that the cumulus in the rainfall system is not strong in the East Asian monsoon region.
文摘The reliability of the numerical K ε model for determining wind pressure on building surfaces is evaluated. The solution algorithm is based on a body fitted non orthogonal curvilinear coordinate system and a staggered grid arrangement. The covariant velocity components are chosen as dependent variables. Convective fluxes are described by the Power Law Scheme. The grids are generated with an elliptic grid generator using control functions. The results compare favorably with those by Oxford wind tunnel measurements.
文摘A high resolution, nonhydrostatic, three dimensional diagnostic PBL model over small scale concave terrain was established in this paper. A two dimensional prognostic model was developed based on the diagnostic model. The hydrostatic approximation was abandoned and the simple energy ( E e ) closure scheme was used in both models. Using the two models, characteristics of PBL structure and its evolution were fully studied. The main characteristic of the PBL is the circulation, and it fairly affects the distribution of the pollutant in the pit.
文摘According to the precursory data of the 1976 Tangshan earthquake( M =7.8), and combining with the research results of rock fracture, seismic source, tectonics, seismic precursors, dynamic condition and crust structure, the seismogenic process of Tangshan earthquake has been numerically simulated by using the model of water saturated porous medium with a rhombic hard inclusion. First, a system of seismogenic dynamics equations of solid liquid two phase medium has been set up under considering rock inelastic dilation, strain softening and pore water permeation. Then, the finite difference method to solve the equation system in incremental form has been presented. Finally, the seismogenic process of Tangshan earthquake and the temporal spatial characteristics of its precursors have been numerically simulated when the hard inclusion includes a soft fault belt. The numerically simulating result shows that the development of Tangshan earthquake mainly undergoes following processes: elastic accumulation, early inelastic cubic dilation, accelerative softening (failure and creep) of fault first time, inelastic dilation twice in Tianjin—Ninghe area, accelerative softening of fault twice and instability. Corresponding to the fault accelerative softening, elastic recovery and inelastic dilation twice in some parts of seismogenic medium. By comparing with the data of precursory observation, ones can find the preceding simulating result explains the varied characters of practical data better. Meanwhile, the numerical simulation further displays the temporal spatial change law and complex patterns of the field of Tangshan earthquake development as well. It makes a base study for the physical mechanism of change of the seismic precursory field.
文摘In this paper,the Pennsylvania State University-NCAR Mesoscale Model (MM4)is used to investigate the explosive oceanic cyclone of 14-15 March 1988 over the warm Kuroshio Current. A series of numerical simulations on this cyclogenesis indicates that the favorable weather conditions and strong baroclinity in the low- and middle-level are essential to its explosive development. The explosive cyclogenesis occurred over a wide range of sea surface temperatures (SST′s),which was then characterized by strong baroclinity,the low-level jet (LLJ) was initially formed under the favorable atmospheric circulation and then this LLJ advected the moisture and heat northward for the explosive development of the cyclone,the LLJ played an important role in the process of cyclogenesis.Sensitivity experiments show that the latent heating was a key factor to explosive cyclogenesis,the latent heating deepened the short-wave trough,which resulted in the rapid intensification of the cyclone; while in the explosive intensification stage and continuous development stage, there was less contribution of local surface processes for the explosion of the cyclone.
文摘The distributive law of flow rate is studiedfor highly viscoelastic flow in threedimensional slit channel with varying thickness by using Finite Block Element Method(FBM).As an example.the influence of restrictive block on.flow rate is obtained in fish channel of the plate extruding die and the results of numerical simulation are in concordance withthe approximatical analytical solution.It is proved that FBM can be considered as an important toolfor CAD/CAM.
文摘The latest progress on the study of numerical simulation of mold filling and solidification process of shaped casting is reviewed. In mold filling process simulation of castings, the SOLA VOF algorithmis is improved in efficient free surface treatment and turbulence consideration, and parallel computational techniques are implemented to accelerate the fluid flow calculation time as well. Methods for predication of shrinkage defects of steel castings and S G. iron castings are developed based on the solidification simulation. In order to reduce the residual stress and deformation of castings, a combined FDM/FEM method is implemented for the modelling of stresses. Numerical models for the simulation of micro structure and prediction of mechanical properties of S G. iron are developed. The verifications and applications of the simulation software show that the models and techniques adopted in current research work are efficient and appropriate for the numerical simulation of shaped castings.
文摘Based on a simplified media model of Gonghe area, the precursor characteristics of Gonghe M 7.0 earthquake in 1990 are simulated in this paper by using the constitutive relationship of binary medium (solid and water). The results show that the simulated state distribution and extension variation of media are identical with the spatial and temporal distribution of reliable anomalies before Gonghe earthquake. The study also suggests that the development of the Gonghe earthquake has experienced a series of processes such as elastic deformation of large scale, early nonelastic dilatation, strain softening and elastic recovery in the neighbour region of Xining, nonelasscale, early nonelastic dilatation, strain softening and elastic recovery in the neighbour region of nonelastic dilatation of high dense block near seismic source and earthquake occurrence. Therefore, it can be concluded that this earthquake development is neither a simple process for fissures developing and linking up with one another, nor a process of nonelastic volume expanion and water flowing into medium around seismic source, conrary, it is a complicated medium saate changing process, and the style of such changing depends on geological structure environment of seismic source and its neighbour region. It is considered that different earthquakes are accompanied by different geological conditions, the spatial and temporal behavior of their precusors are certainly different.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
基金financially supported by the National Natural Science Foundation of China(No.51904026)the Fundamental Research Funds for the Central Universities(No.06500108)。
文摘Hydrogen displays the potential to partially replace pulverized coal injection(PCI)in the blast furnace,and it can reduce CO_(2)emissions.In this paper,a three-dimensional mathematical model of hydrogen and pulverized coal co-injection in blast furnace tuyere was established through numerical simulation,and the effect of hydrogen injection and oxygen enrichment interaction on pulverized coal combustion and raceway smelting was investigated.The simulation results indicate that when the coal injection rate decreased from 36 to 30t/h and the hydrogen injection increased from 0 to 3600 m^(3)/h,the CO_(2)emissions decreased from 1860 to 1551 kg/t,which represents a16.6%reduction,and the pulverized coal burnout decreased from 70.1%to 63.7%.The heat released from hydrogen combustion can not only promote the volatilization of pulverized coal but also affect the combustion reaction between volatilization and oxygen,which resulted in a decrease in the temperature at the end of the raceway.Co-injection of hydrogen with PCI increased the wall temperature near the upper half part of the raceway and at the outlet of the tuyere,which required a high cooling efficiency to extend the service life of the blast furnace.The increase in oxygen level compensated for the decreased average temperature in the raceway due to hydrogen injection.The increase in the oxygen content by 3%while maintaining constant hydrogen and PCI injection rates increased the burnout and average raceway temperature by 4.2%and 43 K,respectively.The mole fraction of CO and H_(2) production increased by 0.04 and 0.02,respectively.Burnout can be improved through optimization of the particle size distribution of pulverized coal.
基金supported by the National Natural Science Foundation of China (Grant No.52108361)the Sichuan Science and Technology Program of China (Grant No.2023YFS0436)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No.SKLGP2022Z015).
文摘Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030001)the National Key Research and Development Program of China(Grant No.2021YFB3802300)the Foundation of National Key Laboratory of Shock Wave and Detonation Physics(Grant No.JCKYS2022212004)。
文摘The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to achieving controllable stress-strain rate loading.In this study,we have,for the first time,combined one-dimensional fluid computational software with machine learning methods.We first elucidated the mechanisms by which GDI structures control stress and strain rates.Subsequently,we constructed a machine learning model to create a structure-property response surface.The results show that altering the loading velocity and interlayer thickness has a pronounced regulatory effect on stress and strain rates.In contrast,the impedance distribution index and target thickness have less significant effects on stress regulation,although there is a matching relationship between target thickness and interlayer thickness.Compared with traditional design methods,the machine learning approach offers a10^(4)—10^(5)times increase in efficiency and the potential to achieve a global optimum,holding promise for guiding the design of GDI.
基金Jiangsu Provincial Natural Science Foundation of China(BK20211232)2023 Major Science and Technology Projects of Nanjing City(202309011)。
文摘To further reduce the explosive thickness and to improve the bonding quality of titanium/steel composite plates,explosive welding experiments of TA1/Q235 were conducted using a low detonation velocity explosive(53#)under the guidance of the explosive welding lower limit principle with the flyer plate thicknesses of 1,2,and 4 mm and gaps of 3,6,and 8 mm.The weldability window for titanium/steel explosive welding was calculated,and a quantitative relationship between dynamic and static process parameters was developed.Aβ-V_(p) high-speed inclined collision model was proposed,and two-dimensional numerical simulations for the explosive welding tests were performed using the smoothed particle hydrodynamics(SPH)algorithm,revealing the growth evolution mechanisms of the typical waveform morphology characteristics.Through microstructural characterization techniques,such as optical microscope,scanning electron microscope,energy dispersive spectrometer,and electron backscattered diffractometer,and mechanical property tests in terms of shear strength,bending performance,and impact toughness,the microstructure and mechanical properties of the interfaces of explosively welded TA1/Q235 composite plates were investigated.Results show that the quality of interface bonding is excellent,presenting typical waveform morphology with an average interface shear strength above 330 MPa and an average impact toughness exceeding 81 J.All samples can be bent to 180°without significant delamination or cracking defects.
基金National Natural Science Foundation of China(51971103)Key Research and Development Program in Gansu Province(20YF8GA052)。
文摘A suction casting experiment was conducted on Zr_(55)Cu_(30)Al_(10)Ni_(5)(at%)amorphous alloy.Using ProCAST software,numerical simulations were performed to analyze the filling and solidification processes.The velocity field during the filling process and the temperature field during the solidification process of the alloy melt under different process parameters were obtained.Based on the simulation results,a Zr-based amorphous alloy micro-gear was prepared via casting.The results indicate that increasing the suction casting temperature enhances the fluidity of alloy melt but induces unstable flow rate during filling,which is detrimental to complete filling.Zr-based amorphous micro-gears with a module of 0.6 mm,a tooth top diameter of 8 mm,and 10 teeth were prepared through the suction casting.X-ray diffraction and differential scanning calorimetry analyses confirm that the fabricated micro-gear exhibits characteristic amorphous structural features,demonstrating well-defined geometrical contours and satisfactory forming completeness.
基金the National Natural Science Foundation of China(No.52074182)Joint Funds of the National Natural Science Foundation of China(No.U23A20612).
文摘We proposed a new technique route of directional solidification for the manufacture of super slab.A 7-t laboratory-scale thick slab was casted and characterised for trial.To further understand the process,the evolution of the multiple physical fields during the directional solidification was simulated and verified.Similar to the convectional ingot casting,a negative segregated cone of equiaxed grains was formed at the bottom,and a seriously positive segregated region was formed beneath the top surface of the slab.Specific measures on the lateral walls,base plate,and free surface were strongly recommended to ensure that the slab is relatively directionally casted.A water-cooling copper base plate accelerates the solidification rate and the columnar growth along the vertical direction.It inhibits the sedimentation of equiaxed grains and enlarges the columnar zone.Based on the simulation analysis,it can be concluded that the directional solidification technique route is promising to manufacture super slab with lower segregation level,and less porosities and inclusions.
基金supported by the National Key Research and Development Program of China(2022YFC2904400)Guangxi Science and Technology Major Project(Gui Ke AA23023033)。
文摘As a pyrometallurgical process,circulating fluidized bed(CFB) roasting has good potential for application in desulfurization of high-sulfur bauxite.The gas-solid distribution and reaction during CFB roasting of high-sulfur bauxite were simulated using the computational particle fluid dynamics(CPFD) method.The effect of primary air flow velocity on particle velocity,particle volume distribution,furnace temperature distribution and pressure distribution were investigated.Under the condition of the same total flow of natural gas,the impact of the number of inlets on the desulfurization efficiency,atmosphere mass fraction distribution and temperature distribution in the furnace was further investigated.
基金Projects(U23A2060,42177143)supported by the National Natural Science Foundation of China。
文摘To elucidate the influence of confining pressure on microcrack evolution and macroscopic failure mechanisms in granite,a multi-perspective approach was adopted.This approach combined triaxial compression tests,acoustic emission(AE)monitoring,and PFC simulations.The results show that:1)Confining pressure exhibits a pronounced linear correlation with both yield strength and compressive strength.The enhancement of confining pressure significantly improves the deformability of granite and promotes a progressive shift in failure mechanism from brittle rupture to ductile deformation;2)Increasing confining pressure elevates the stress threshold for microcrack initiation and suppresses crack propagation.As a result,the proportion of shear cracks increases(based on AE analysis)from 18.71%to 61.2%,marking a transition in the dominant failure mode from tensile to shear;3)Confining pressure facilitates the development of grain boundary shear cracks(GBSCs),establishing the primary damage pathways.In addition,local stress concentrations under high confinement conditions trigger intragranular cracking.This highlights the regulatory effect of confining pressure on microcrack evolution.
