Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus...Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality.Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit(ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit(MCF) method, based on the 'bidisperse' diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation(USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, t展开更多
Background:Colorectal cancer(CRC)is the fourth cause of cancer death in China.We aimed to provide national and subnational estimates and changes of CRC premature mortality burden during 2005–2020.Methods:Data from mu...Background:Colorectal cancer(CRC)is the fourth cause of cancer death in China.We aimed to provide national and subnational estimates and changes of CRC premature mortality burden during 2005–2020.Methods:Data from multi-source on the basis of the national surveillance mortality system were used to estimate mortality and years of life lost(YLL)of CRC in the Chinese population during 2005–2020.Estimates were generated and compared for 31 provincial-level administrative divisions in China.Results:Estimated CRC deaths increased from 111.41 thousand in 2005 to 178.02 thousand in 2020;age-standardized mortality rate decreased from 10.01 per 100,000 in 2005 to 9.68 per 100,000 in 2020.Substantial reduction in CRC premature mortality burden,as measured by age-standardized YLL rate,was observed with a reduction of 10.20%nationwide.Marked differences were observed in the geographical patterns of provincial units,and they appeared to be obvious in areas with higher economic development.Population aging was the dominant driver which contributed to the increase in CRC deaths,followed by population growth and age-specific mortality change.Conclusions:Substantial discrepancies were observed in the premature mortality burden of CRC across China.Targeted considerations were needed to promote a healthy lifestyle,expand cost-effective CRC early screening and diagnosis,and improve medical treatment to reduce CRC mortality among high-risk populations and regions with inadequate healthcare resources.展开更多
The microstructure and mechanical properties of Mg-10.1Gd-3.74Y-0.25Zr （mass fraction, %） alloy （GW104 alloy） cast by metal mould casting （MMC） and lost foam casting （LFC） were evaluated, respectively. It is r...The microstructure and mechanical properties of Mg-10.1Gd-3.74Y-0.25Zr （mass fraction, %） alloy （GW104 alloy） cast by metal mould casting （MMC） and lost foam casting （LFC） were evaluated, respectively. It is revealed that different forming modes do not influence the phase composition of as-cast alloy. In the as-cast specimens, the microstructures are similar and composed of α-Mg solid solution, eutectic compound of α-Mg＋Mg 24 （Gd, Y） 5 and cuboid-shaped Mg 5 （Gd, Y） phase; whereas the average grain size of the alloy produced by metal mould casting is smaller than that by lost foam casting. The eutectic compound of the alloy is completely dissolved after solution treatment at 525 ℃for 6 h, while the Mg 5 （Gd, Y） phase still exists after solution treatment. After peak-ageing, the lost foam cast alloy exhibits the maximum ultimate tensile strength of 285 MPa, and metal mould cast specimen 325 MPa at room temperature, while the tensile yield strengths of them are comparable. It can be concluded that GW104 alloy cast by lost foam casting possesses similar microstructure and evidently lower mechanical strength compared with metal mould cast alloy, due to slow solidification rate and proneness to form shrinkage porosities during lost foam casting process.展开更多
The differences of coalbed methane(CBM) desorption-diffusion from coal drilling-core under various drilling fluid medium are not considered in the present calculating methods of lost CBM quantity,which leads possibly ...The differences of coalbed methane(CBM) desorption-diffusion from coal drilling-core under various drilling fluid medium are not considered in the present calculating methods of lost CBM quantity,which leads possibly to the inaccuracy of CBM quantity in coal seam.Here we took the desorption of CBM from coal core under drilling fluid medium as a pressure-swing process,and based on the Langmuir equation and Fick-first law,established the desorption-diffusion model and numerical modeling method of lost gas(including free CBM) calculation in coal core under various drilling fluid mediums through physical simulation test and by considering comprehensively primary factors.The results showed that the physical simulated t-Qt curves can be rightly fitted by the numerical modeling data,which indicated the ultimate desorption quantity from the numerical modeling was adjacent to that from the physical simulation as a whole.It was found that the lost CBM quantity from the modeling method was generally higher than that from the direct method when lost time was relatively long.Thus,we sug-gest that it is necessary to emend the active China national standard through further investigation,since the lost CBM quantity from coal drilling-core was generally underestimated using the method in the current standard.展开更多
By reviewing the mechanisms of drilling fluid lost circulation and its control in fractured formations, the applicability and working mechanisms of different kinds of lost circulation materials in plugging fractured f...By reviewing the mechanisms of drilling fluid lost circulation and its control in fractured formations, the applicability and working mechanisms of different kinds of lost circulation materials in plugging fractured formations have been summarized. Meanwhile, based on the types of lost circulation materials, the advantages, disadvantages, and application effects of corresponding plugging technologies have been analyzed to sort out the key problems existing in the current lost circulation control technologies. On this basis, the development direction of plugging technology for severe loss have been pointed out. It is suggested that that the lost circulation control technology should combine different disciplines such as geology, engineering and materials to realize integration, intelligence and systematization in the future. Five research aspects should be focused on:(1) the study on mechanisms of drilling fluid lost circulation and its control to provide basis for scientific selection of lost circulation material formulas, control methods and processes;(2) the research and development of self-adaptive lost circulation materials to improve the matching relationship between lost control materials and fracture scales;(3) the research and development of lost circulation materials with strong retention and strong filling in three-dimensional fracture space, to enhance the retention and filling capacities of materials in fractures and improve the lost circulation control effect;(4) the research and development of lost circulation materials with high temperature tolerance, to ensure the long-term plugging effect of deep high-temperature formations;(5) the study on digital and intelligent lost circulation control technology, to promote the development of lost circulation control technology to digital and intelligent direction.展开更多
Impact, friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage. Liner, made from Hadfield steel or alloyed steel, could not have served in wet gri...Impact, friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage. Liner, made from Hadfield steel or alloyed steel, could not have served in wet grinding environment for more than ten months. Composite liner, made from HCWCI (high Cr white cast iron) and carbon steel, has been developed successfully with liquid-liquid composing process based on LFC (lost foam casting). The microstructure of composite was analyzed with optical microscope, SEM (scanning electron microscope)/EDX energy-dispersive X-ray and XRD (X-ray diffraction). According to micrograph, the combination region of two metals was staggered like dogtooth, no mixtures occurred between two liquid metals, and its interface presented excellent metallurgical bonding state. The results of mechanical property test show that, the hardness of HRC, the fracture toughness, and the bending strength are more than 61, 16.5 J/cm2 and 1 600 MPa, respectively. Comparison between liners made from bimetal composite and alloyed steel has also been investigated in industrial hematite ball mill. The results of eight months test in wet grinding environment prove that the service life of bimetal composite liner is three times as long as that of one made from alloyed steel.展开更多
The analytical mathematical solutions of gas concentration and fractional gas loss for the diffusion of gas in a cylindrical coal sample were given with detailed mathematical derivations by assuming that the diffusion...The analytical mathematical solutions of gas concentration and fractional gas loss for the diffusion of gas in a cylindrical coal sample were given with detailed mathematical derivations by assuming that the diffusion of gas through the coal matrix is concentration gradient-driven and obeys the Fick’s Second Law of Diffusion.The analytical solutions were approximated in case of small values of time and the error analyses associated with the approximation were also undertaken.The results indicate that the square root relationship of gas release in the early stage of desorption,which is widely used to provide a simple and fast estimation of the lost gas,is the first term of the approximation,and care must be taken in using the square root relationship as a significant error might be introduced with increase in the lost time and decrease in effective diameter of a cylindrical coal sample.展开更多
Prediction the inside environment variables in greenhouses is very important because they play a vital role in greenhouse cultivation and energy lost especially in cold and hot regions.The greenhouse environment is an...Prediction the inside environment variables in greenhouses is very important because they play a vital role in greenhouse cultivation and energy lost especially in cold and hot regions.The greenhouse environment is an uncertain nonlinear system which classical modeling methods have some problems to solve it.So the main goal of this study is to select the best method between Artificial Neural Network(ANN)and Support Vector Machine(SVM)to estimate three different variables include inside air,soil and plant temperatures(Ta,Ts,Tp)and also energy exchange in a polyethylene greenhouse in Shahreza city,Isfahan province,Iran.The environmental factors which influencing all the inside temperatures such as outside air temperature,wind speed and outside solar radiation were collected as data samples.In this research,13 different training algorithms were used for ANN models(MLPRBF).Based on K-fold cross validation and Randomized Complete Block(RCB)methodology,the best model was selected.The results showed that the type of training algorithm and kernel function are very important factors in ANN(RBF and MLP)and SVM models performance,respectively.Comparing RBF,MLP and SVM models showed that the performance of RBF to predict Ta,Tp and Ts variables is better according to small values of RMSE and MAPE and large value of R2 indices.The range of RMSE and MAPE factors for RBF model to predict Ta,Tp and Ts were between 0.07 and 0.12C and 0.28-0.50%,respectively.Generalizability and stability of the RBF model with 5-fold cross validation analysis showed that this method can use with small size of data groups.The performance of best model(RBF)to estimate the energy lost and exchange in the greenhouse with heat transfer models showed that this method can estimate the real data in greenhouse and then predict the energy lost and exchange with high accuracy.展开更多
Liners in wet ball mill for mineral processing industry must bear abrasive wear and corrosive wear, and consequently, the service life of the liner made from traditional materials, such as Hadfield steel and alloyed s...Liners in wet ball mill for mineral processing industry must bear abrasive wear and corrosive wear, and consequently, the service life of the liner made from traditional materials, such as Hadfield steel and alloyed steels, is typically less than ten months. Bimetal liner, made from high Cr white cast iron and carbon steel, has been successfully developed by using liquid-liquid composite lost foam casting process. The microstructure and interface of the composite were analyzed using optical microscope, SEM, EDX and XRD. Micrographs indicate that the boundary of bimetal combination regions is staggered like dogtooth, two liquid metals are not mixed, and the interface presents excellent metallurgical bonding state. After heat treatment, the composite liner specimens have shown excellent properties, including hardness 〉 61 HRC, fracture toughness ak 〉16.5 J.cm2 and bending strength 〉1,600 MPa. Wear comparison was made between the bimetal composite liner and alloyed steel liner in an industrial hematite ball mill of WISCO, and the results of eight-month test in wet grinding environment have proved that the service life of the bimetal composite liner is three times as long as that of the alloyed steel liner.展开更多
In lost foam casting (LFC), the distribution of polymer beads during the bead filling process is not uniform, and the collision between polymer beads determines the distribution of two-phase flow of gas and solid. The...In lost foam casting (LFC), the distribution of polymer beads during the bead filling process is not uniform, and the collision between polymer beads determines the distribution of two-phase flow of gas and solid. The interaction between the gas and solid phases reveals as coupling effect of the force that gas exerts on particles or vice versa, or that among particles. The gas-solid flow in filling process is nonlinearity, which makes the coupling effect an essential point to carry out a simulation properly. Therefore, information of each particle's motion is important for acquiring the law of filling process. In bead filling process, compressed air is pressed into mold cavity, and discharged from gas vent, creating a pressure difference between outer and inner space near the gas vent. This pressure difference directly changes the spatial distribution and motion trace of gas and solid phases. In this paper, Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) are employed to simulate the fluid dynamic character based on Newton's Third Law of Motion. The simulation results of some casting products such as pressure plate and valve handle are compared with the result obtained from practical experiment in order to test the feasibility of DEM. The comparison shows that this DEM method can be a very promising tool in the mould filling simulation of beads' movement.展开更多
文摘Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study,eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality.Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit(ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit(MCF) method, based on the 'bidisperse' diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation(USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, t
基金the National Key Research&Development Program of the Ministry of Science and Technology of the People’s Republic of China(No.2018YFC1315301)Taikang Yicai Public Health and Epidemic Control Fund.
文摘Background:Colorectal cancer(CRC)is the fourth cause of cancer death in China.We aimed to provide national and subnational estimates and changes of CRC premature mortality burden during 2005–2020.Methods:Data from multi-source on the basis of the national surveillance mortality system were used to estimate mortality and years of life lost(YLL)of CRC in the Chinese population during 2005–2020.Estimates were generated and compared for 31 provincial-level administrative divisions in China.Results:Estimated CRC deaths increased from 111.41 thousand in 2005 to 178.02 thousand in 2020;age-standardized mortality rate decreased from 10.01 per 100,000 in 2005 to 9.68 per 100,000 in 2020.Substantial reduction in CRC premature mortality burden,as measured by age-standardized YLL rate,was observed with a reduction of 10.20%nationwide.Marked differences were observed in the geographical patterns of provincial units,and they appeared to be obvious in areas with higher economic development.Population aging was the dominant driver which contributed to the increase in CRC deaths,followed by population growth and age-specific mortality change.Conclusions:Substantial discrepancies were observed in the premature mortality burden of CRC across China.Targeted considerations were needed to promote a healthy lifestyle,expand cost-effective CRC early screening and diagnosis,and improve medical treatment to reduce CRC mortality among high-risk populations and regions with inadequate healthcare resources.
基金Project(2007CB613704)supported by the National Basic Research Program of China
文摘The microstructure and mechanical properties of Mg-10.1Gd-3.74Y-0.25Zr （mass fraction, %） alloy （GW104 alloy） cast by metal mould casting （MMC） and lost foam casting （LFC） were evaluated, respectively. It is revealed that different forming modes do not influence the phase composition of as-cast alloy. In the as-cast specimens, the microstructures are similar and composed of α-Mg solid solution, eutectic compound of α-Mg＋Mg 24 （Gd, Y） 5 and cuboid-shaped Mg 5 （Gd, Y） phase; whereas the average grain size of the alloy produced by metal mould casting is smaller than that by lost foam casting. The eutectic compound of the alloy is completely dissolved after solution treatment at 525 ℃for 6 h, while the Mg 5 （Gd, Y） phase still exists after solution treatment. After peak-ageing, the lost foam cast alloy exhibits the maximum ultimate tensile strength of 285 MPa, and metal mould cast specimen 325 MPa at room temperature, while the tensile yield strengths of them are comparable. It can be concluded that GW104 alloy cast by lost foam casting possesses similar microstructure and evidently lower mechanical strength compared with metal mould cast alloy, due to slow solidification rate and proneness to form shrinkage porosities during lost foam casting process.
基金supported by the Key Project of National Natural Science Foundation of China (Grant No.40730422)Young Project of National Natural Science Foundation of China (Grant No.40802032)
文摘The differences of coalbed methane(CBM) desorption-diffusion from coal drilling-core under various drilling fluid medium are not considered in the present calculating methods of lost CBM quantity,which leads possibly to the inaccuracy of CBM quantity in coal seam.Here we took the desorption of CBM from coal core under drilling fluid medium as a pressure-swing process,and based on the Langmuir equation and Fick-first law,established the desorption-diffusion model and numerical modeling method of lost gas(including free CBM) calculation in coal core under various drilling fluid mediums through physical simulation test and by considering comprehensively primary factors.The results showed that the physical simulated t-Qt curves can be rightly fitted by the numerical modeling data,which indicated the ultimate desorption quantity from the numerical modeling was adjacent to that from the physical simulation as a whole.It was found that the lost CBM quantity from the modeling method was generally higher than that from the direct method when lost time was relatively long.Thus,we sug-gest that it is necessary to emend the active China national standard through further investigation,since the lost CBM quantity from coal drilling-core was generally underestimated using the method in the current standard.
基金Supported by National Natural Science Foundation of China(51991361,52074327,U1762212)Major Engineering Technology Field Tes Project of CNPC(2020F-45)。
文摘By reviewing the mechanisms of drilling fluid lost circulation and its control in fractured formations, the applicability and working mechanisms of different kinds of lost circulation materials in plugging fractured formations have been summarized. Meanwhile, based on the types of lost circulation materials, the advantages, disadvantages, and application effects of corresponding plugging technologies have been analyzed to sort out the key problems existing in the current lost circulation control technologies. On this basis, the development direction of plugging technology for severe loss have been pointed out. It is suggested that that the lost circulation control technology should combine different disciplines such as geology, engineering and materials to realize integration, intelligence and systematization in the future. Five research aspects should be focused on:(1) the study on mechanisms of drilling fluid lost circulation and its control to provide basis for scientific selection of lost circulation material formulas, control methods and processes;(2) the research and development of self-adaptive lost circulation materials to improve the matching relationship between lost control materials and fracture scales;(3) the research and development of lost circulation materials with strong retention and strong filling in three-dimensional fracture space, to enhance the retention and filling capacities of materials in fractures and improve the lost circulation control effect;(4) the research and development of lost circulation materials with high temperature tolerance, to ensure the long-term plugging effect of deep high-temperature formations;(5) the study on digital and intelligent lost circulation control technology, to promote the development of lost circulation control technology to digital and intelligent direction.
基金Item Sponsored by National Natural Science Foundation of China (50805109)Fundamental Research Funds for Central Universities of China (2011-1a-023)
文摘Impact, friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage. Liner, made from Hadfield steel or alloyed steel, could not have served in wet grinding environment for more than ten months. Composite liner, made from HCWCI (high Cr white cast iron) and carbon steel, has been developed successfully with liquid-liquid composing process based on LFC (lost foam casting). The microstructure of composite was analyzed with optical microscope, SEM (scanning electron microscope)/EDX energy-dispersive X-ray and XRD (X-ray diffraction). According to micrograph, the combination region of two metals was staggered like dogtooth, no mixtures occurred between two liquid metals, and its interface presented excellent metallurgical bonding state. The results of mechanical property test show that, the hardness of HRC, the fracture toughness, and the bending strength are more than 61, 16.5 J/cm2 and 1 600 MPa, respectively. Comparison between liners made from bimetal composite and alloyed steel has also been investigated in industrial hematite ball mill. The results of eight months test in wet grinding environment prove that the service life of bimetal composite liner is three times as long as that of one made from alloyed steel.
基金provided by the Science and Technology Grant of Huainan City of China (No.2013A4001)the Key Research Grant of Shanxi Province of China (No.201303027-1)
文摘The analytical mathematical solutions of gas concentration and fractional gas loss for the diffusion of gas in a cylindrical coal sample were given with detailed mathematical derivations by assuming that the diffusion of gas through the coal matrix is concentration gradient-driven and obeys the Fick’s Second Law of Diffusion.The analytical solutions were approximated in case of small values of time and the error analyses associated with the approximation were also undertaken.The results indicate that the square root relationship of gas release in the early stage of desorption,which is widely used to provide a simple and fast estimation of the lost gas,is the first term of the approximation,and care must be taken in using the square root relationship as a significant error might be introduced with increase in the lost time and decrease in effective diameter of a cylindrical coal sample.
基金supported by a grant(961/06)from Ramin Agriculture and Natural Resources University of Khuzestan,Iran.
文摘Prediction the inside environment variables in greenhouses is very important because they play a vital role in greenhouse cultivation and energy lost especially in cold and hot regions.The greenhouse environment is an uncertain nonlinear system which classical modeling methods have some problems to solve it.So the main goal of this study is to select the best method between Artificial Neural Network(ANN)and Support Vector Machine(SVM)to estimate three different variables include inside air,soil and plant temperatures(Ta,Ts,Tp)and also energy exchange in a polyethylene greenhouse in Shahreza city,Isfahan province,Iran.The environmental factors which influencing all the inside temperatures such as outside air temperature,wind speed and outside solar radiation were collected as data samples.In this research,13 different training algorithms were used for ANN models(MLPRBF).Based on K-fold cross validation and Randomized Complete Block(RCB)methodology,the best model was selected.The results showed that the type of training algorithm and kernel function are very important factors in ANN(RBF and MLP)and SVM models performance,respectively.Comparing RBF,MLP and SVM models showed that the performance of RBF to predict Ta,Tp and Ts variables is better according to small values of RMSE and MAPE and large value of R2 indices.The range of RMSE and MAPE factors for RBF model to predict Ta,Tp and Ts were between 0.07 and 0.12C and 0.28-0.50%,respectively.Generalizability and stability of the RBF model with 5-fold cross validation analysis showed that this method can use with small size of data groups.The performance of best model(RBF)to estimate the energy lost and exchange in the greenhouse with heat transfer models showed that this method can estimate the real data in greenhouse and then predict the energy lost and exchange with high accuracy.
基金supported by the National Natural Science Foundation of China under grant No.50805109the Fundamental Research Funds for the Central Universities under grant No.2011-1a-023
文摘Liners in wet ball mill for mineral processing industry must bear abrasive wear and corrosive wear, and consequently, the service life of the liner made from traditional materials, such as Hadfield steel and alloyed steels, is typically less than ten months. Bimetal liner, made from high Cr white cast iron and carbon steel, has been successfully developed by using liquid-liquid composite lost foam casting process. The microstructure and interface of the composite were analyzed using optical microscope, SEM, EDX and XRD. Micrographs indicate that the boundary of bimetal combination regions is staggered like dogtooth, two liquid metals are not mixed, and the interface presents excellent metallurgical bonding state. After heat treatment, the composite liner specimens have shown excellent properties, including hardness 〉 61 HRC, fracture toughness ak 〉16.5 J.cm2 and bending strength 〉1,600 MPa. Wear comparison was made between the bimetal composite liner and alloyed steel liner in an industrial hematite ball mill of WISCO, and the results of eight-month test in wet grinding environment have proved that the service life of the bimetal composite liner is three times as long as that of the alloyed steel liner.
基金supported by The Second Doctor Innovative Projects of Shenzhen Institute of Information Technology (BC2009013)
文摘In lost foam casting (LFC), the distribution of polymer beads during the bead filling process is not uniform, and the collision between polymer beads determines the distribution of two-phase flow of gas and solid. The interaction between the gas and solid phases reveals as coupling effect of the force that gas exerts on particles or vice versa, or that among particles. The gas-solid flow in filling process is nonlinearity, which makes the coupling effect an essential point to carry out a simulation properly. Therefore, information of each particle's motion is important for acquiring the law of filling process. In bead filling process, compressed air is pressed into mold cavity, and discharged from gas vent, creating a pressure difference between outer and inner space near the gas vent. This pressure difference directly changes the spatial distribution and motion trace of gas and solid phases. In this paper, Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) are employed to simulate the fluid dynamic character based on Newton's Third Law of Motion. The simulation results of some casting products such as pressure plate and valve handle are compared with the result obtained from practical experiment in order to test the feasibility of DEM. The comparison shows that this DEM method can be a very promising tool in the mould filling simulation of beads' movement.
