Pilot scale chlorination of TiO2 was carried out with CO as reducing agent.The experimental analysis and modeling of chlorination process of TiO2 in the presence of CO and Cl2 in a semi-continuous fluidized bed reacto...Pilot scale chlorination of TiO2 was carried out with CO as reducing agent.The experimental analysis and modeling of chlorination process of TiO2 in the presence of CO and Cl2 in a semi-continuous fluidized bed reactor were aimed.Chlorination process was continuously monitored by measuring the amount of produced TiCl4 with time.The effects of different operating parameters including chlorination temperature,feedstock particle size and size distribution,amount of feedstock and Cl2 and CO flow rates on the conversion were systematically investigated.A gradual increase in chlorination temperature led to monotonous increase of conversion rate.Conversion decreased with increased particle size of feedstock.An increase in loaded feedstock led to a decrease in reaction conversion.A model was proposed to predict conversion,particle size distribution and mole fraction of components in gas phase as reaction proceeds.A good agreement between conversions predicted by the model and experimental data under various operating conditions was observed.展开更多
This article discusses China＇s economic growth path and the potential challenges to becoming a high-income country by utilizing simulation to provide potential policy responses. The authors believe it is necessary to...This article discusses China＇s economic growth path and the potential challenges to becoming a high-income country by utilizing simulation to provide potential policy responses. The authors believe it is necessary to optimize spatial allocation and promote urbanization, but distorted urbanization must be avoided as it will only perpetuate the current problems. The core strategy is to change government behavior to allow the market to allocate resources. It is important to maintain stable growth in the short term and balance the economic structure in the medium- and long-term. In particular, optimizing spatial allocation must constitute a critical part of the policy adjustment. Only with a viable urbanization model can the country shift from the catch-up pursuit via industrialization to a balanced approach of sustainable growth. This can be done through gradual guidance and policy corrections. China should continue to uphold the ＂scientific concept of development＂ as the overarching principle governing socioeconomic development, and create a unique approach to sustainability where the economy grows steadily, sharing is universal and people live in harmony with nature.展开更多
This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stif...This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.展开更多
One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temper...One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temperature and pressure along the height in the two converters, respectively. Design optimization methods of the two converters have been proposed, by which the minimum catalyst volume can be obtained to satisfy the productive capacity of 1000 tons per day, when the operating pressure is 15.0, 10.0 and 7.5 MPa, respectively.展开更多
Carbon capture and storage technology have been rapidly developed to reduce the carbon dioxide(CO2)emission into the environment.It has been found that the amine-based organic molecules could absorb CO_(2) efficiently...Carbon capture and storage technology have been rapidly developed to reduce the carbon dioxide(CO2)emission into the environment.It has been found that the amine-based organic molecules could absorb CO_(2) efficiently and form the bicarbonate salts through hydrogen-bond(H-bond)interactions.Recently,the aqueous 1,3-diphenylguanidine(DPG)solution was developed to trap and convert CO_(2) to valuable chemicals under ambient conditions.However,how the DPG molecules interact with CO_(2) in an aqueous solution remains unclear.In this work,we perform molecular dynamics simulations to explore the atomistic details of CO_(2) in the aqueous DPG.The simulated results reveal that the protonated DPGH+and the bicarbonate anions prefer to form complexes through different H-bond patterns.These double H-bonds are quite stable in thermodynamics,as indicated from the accurate density functional theory calculations.This study is helpful to understand the catalytic mechanism of CO_(2) conversion in the aqueous DPG.展开更多
A methodology for kinetic modeling of conversion processes is presented.The proposed approach allows to overcome the lack of molecular detail of the petroleum fractions and to simulate the reactions of the process by ...A methodology for kinetic modeling of conversion processes is presented.The proposed approach allows to overcome the lack of molecular detail of the petroleum fractions and to simulate the reactions of the process by means of a two-step procedure.In the first step,a synthetic mixture of molecules representing the feedstock is generated via a molecular reconstruction method,termed SR-REM molecular reconstruction.In the second step,a kinetic Monte Carlo method,termed stochastic simulation algorithm(SSA),is used to simulate the effect of the conversion reactions on the mixture of molecules.The resulting methodology is applied to the Athabasca vacuum residue hydrocracking.An adequate molecular representation of the vacuum residue is obtained using the SR-REM algorithm.The reaction simulations present a good agreement with the laboratory data for Athabasca vacuum residue conversion.In addition,the proposed methodology provides the molecular detail of the vacuum residue conversion throughout the reactions simulations.展开更多
To satisfy the needs of large-scale hydrogen combustion and explosion simulation,a method is presented to establish single-step chemistry model and transport model for fuel-air mixture.If the reaction formula for hydr...To satisfy the needs of large-scale hydrogen combustion and explosion simulation,a method is presented to establish single-step chemistry model and transport model for fuel-air mixture.If the reaction formula for hydrogen-air mixture is H2+0.5O2→H2O,the reaction rate model is ?? =1.13×10?5[H2][O2]exp(?46.37T0/T) mol(cm3 s)?1,and the transport coefficient model is ?=K/CP=ρD=7.0×10?5T 0.7 g(cm s)?1.By using current models and the reference model to simulate steady Zeldovich-von Neumann-Doering(ZND) wave and free-propagating laminar flame,it is found that the results are well agreeable.Additionally,deflagration-to-detonation transition in an obstructed channel was also simulated.The numerical results are also well consistent with the experimental results.These provide a reasonable proof for current method and new models.展开更多
A method of unstructured dynamic overset grids is developed for the numerical simulation of helicopter unsteady rotorairframe aerodynamic interaction.For the effective treatment of the relative motion between the roto...A method of unstructured dynamic overset grids is developed for the numerical simulation of helicopter unsteady rotorairframe aerodynamic interaction.For the effective treatment of the relative motion between the rotor and the airframe,the domain of flowfield is divided into two overset subzones,namely,a rotational subzone containing the blades and a stationary subzone containing the airframe.The overset part of two subzones is used to convect the flow variables of the two zones.The Taylor series expansion is used to obtain a second-order spatial accuracy,and dual-time stepping is adopted to improve the solution accuracy.Mesh deformation from the blade motion in forward flight is treated by using a spring analogy.Validation is made by numerically simulating the flows around a wind tunnel configuration and comparing the predicted time-averaged and instantaneous inflow and airframe surface pressure distributions with the experimental data.It shows that the present method is efficient and robust for the prediction of complicated unsteady rotor-airframe aerodynamic interaction phenomena.展开更多
Five windows such as white glass,Low-E glasses and intelligent glasses are employed for simulation of heating and cooling energy consumptions in five typical cities of China by the software TRNSYS 16.The result shows ...Five windows such as white glass,Low-E glasses and intelligent glasses are employed for simulation of heating and cooling energy consumptions in five typical cities of China by the software TRNSYS 16.The result shows that it is the most energy saving for the doubled glass when the VO 2 films are deposited on the inside surface of the outer pane.And it is 84.7% of energy saving compared with white glass.But the heating energy consumption is the highest.This is because the transition temperature of real intelligent glass is too high and the solar heat gain coefficient is very small when the glass is in the cold state.On this basis,the property of intelligent glass is improved from the theoretical level.The result shows that it can be the most effective way of energy saving when emissivity is 0,solar transmittance is 100% in the cold state;visible light transmittance is 100%,infrared and ultraviolet light transmission rate is 0 in the hot state.Because of the technology limitation,it is hard to lower the transition temperature to below 20℃.The transition temperature of the film should be lower and the emissivity higher as far as possible.展开更多
Objective To observe the efficacy of mild moxibustion combined with arthroscopic meniscal repair in the treatment of meniscal injury and to explore its action mechanism.Methods Ninety-eight patients with meniscal inju...Objective To observe the efficacy of mild moxibustion combined with arthroscopic meniscal repair in the treatment of meniscal injury and to explore its action mechanism.Methods Ninety-eight patients with meniscal injury were divided into a surgery group and a moxibustion plus surgery group by the random number table method,with 49 cases in each group.Both groups received arthroscopic meniscal repair,and the moxibustion plus surgery group was treated with add-on mild moxibustion.The Lysholm score,visual analog scale(VAS)score,and mobility of the affected knee were measured before and after treatment,and transforming growth factor(TGF)-β1 and platelet-derived growth factor(PDGF)levels were measured in the fluid of the affected knee joint.The healing of the meniscus was recorded at a follow-up visit 3 months after the surgery.Results After treatment,the Lysholm score increased,the VAS score decreased in both groups,and the intra-group differences in both groups were statistically significant(P<0.05).The Lysholm score was higher in the moxibustion plus surgery group than in the surgery group,and the VAS score was lower in the moxibustion plus surgery group than in the surgery group.The differences between groups in both scores were statistically significant(P<0.05).The mobility of the affected knee joint increased in both groups(P<0.05),and it was greater in the moxibustion plus surgery group than in the surgery group(P<0.05).When compared with pretreatment,the levels of TGF-β1 and PDGF in the fluid of the knee joint increased in both groups(P<0.05),and the levels of TGF-β1 and PDGF in the fluid of the affected knee joint were higher in the moxibustion plus surgery group than in the surgery group(P<0.05).The healing of the meniscus in the moxibustion plus surgery group was significantly better than that in the surgery group at the follow-up visit 3 months after the surgery(P<0.05).Conclusion The effect of mild moxibustion combined with arthroscopic meniscal repair is better than the surgery alone in improving knee function,relieving pain,increasing mobility of the affected knee,and promoting meniscal healing,which may be related to the up-regulation of TGF-β1 and PDGF levels in the fluid of knee joint.展开更多
文摘Pilot scale chlorination of TiO2 was carried out with CO as reducing agent.The experimental analysis and modeling of chlorination process of TiO2 in the presence of CO and Cl2 in a semi-continuous fluidized bed reactor were aimed.Chlorination process was continuously monitored by measuring the amount of produced TiCl4 with time.The effects of different operating parameters including chlorination temperature,feedstock particle size and size distribution,amount of feedstock and Cl2 and CO flow rates on the conversion were systematically investigated.A gradual increase in chlorination temperature led to monotonous increase of conversion rate.Conversion decreased with increased particle size of feedstock.An increase in loaded feedstock led to a decrease in reaction conversion.A model was proposed to predict conversion,particle size distribution and mole fraction of components in gas phase as reaction proceeds.A good agreement between conversions predicted by the model and experimental data under various operating conditions was observed.
文摘This article discusses China＇s economic growth path and the potential challenges to becoming a high-income country by utilizing simulation to provide potential policy responses. The authors believe it is necessary to optimize spatial allocation and promote urbanization, but distorted urbanization must be avoided as it will only perpetuate the current problems. The core strategy is to change government behavior to allow the market to allocate resources. It is important to maintain stable growth in the short term and balance the economic structure in the medium- and long-term. In particular, optimizing spatial allocation must constitute a critical part of the policy adjustment. Only with a viable urbanization model can the country shift from the catch-up pursuit via industrialization to a balanced approach of sustainable growth. This can be done through gradual guidance and policy corrections. China should continue to uphold the ＂scientific concept of development＂ as the overarching principle governing socioeconomic development, and create a unique approach to sustainability where the economy grows steadily, sharing is universal and people live in harmony with nature.
文摘This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.
文摘One-dimensional pseudo-homogeneous model of an axial flow converter and one-dimensional heteroge-neous model of a horizontal converter have been presented, which describe the distribution of gaseous composition,temperature and pressure along the height in the two converters, respectively. Design optimization methods of the two converters have been proposed, by which the minimum catalyst volume can be obtained to satisfy the productive capacity of 1000 tons per day, when the operating pressure is 15.0, 10.0 and 7.5 MPa, respectively.
基金supported by the National Natural Science Foundation of China(No.21973015 and No.22125301)。
文摘Carbon capture and storage technology have been rapidly developed to reduce the carbon dioxide(CO2)emission into the environment.It has been found that the amine-based organic molecules could absorb CO_(2) efficiently and form the bicarbonate salts through hydrogen-bond(H-bond)interactions.Recently,the aqueous 1,3-diphenylguanidine(DPG)solution was developed to trap and convert CO_(2) to valuable chemicals under ambient conditions.However,how the DPG molecules interact with CO_(2) in an aqueous solution remains unclear.In this work,we perform molecular dynamics simulations to explore the atomistic details of CO_(2) in the aqueous DPG.The simulated results reveal that the protonated DPGH+and the bicarbonate anions prefer to form complexes through different H-bond patterns.These double H-bonds are quite stable in thermodynamics,as indicated from the accurate density functional theory calculations.This study is helpful to understand the catalytic mechanism of CO_(2) conversion in the aqueous DPG.
文摘A methodology for kinetic modeling of conversion processes is presented.The proposed approach allows to overcome the lack of molecular detail of the petroleum fractions and to simulate the reactions of the process by means of a two-step procedure.In the first step,a synthetic mixture of molecules representing the feedstock is generated via a molecular reconstruction method,termed SR-REM molecular reconstruction.In the second step,a kinetic Monte Carlo method,termed stochastic simulation algorithm(SSA),is used to simulate the effect of the conversion reactions on the mixture of molecules.The resulting methodology is applied to the Athabasca vacuum residue hydrocracking.An adequate molecular representation of the vacuum residue is obtained using the SR-REM algorithm.The reaction simulations present a good agreement with the laboratory data for Athabasca vacuum residue conversion.In addition,the proposed methodology provides the molecular detail of the vacuum residue conversion throughout the reactions simulations.
基金supported by EU IIF-FP7 Project (Grant No. 909658)the National Natural Science Foundation of China (Grant No.50806071)the Fundamental Research Funds for the Central Universities of China
文摘To satisfy the needs of large-scale hydrogen combustion and explosion simulation,a method is presented to establish single-step chemistry model and transport model for fuel-air mixture.If the reaction formula for hydrogen-air mixture is H2+0.5O2→H2O,the reaction rate model is ?? =1.13×10?5[H2][O2]exp(?46.37T0/T) mol(cm3 s)?1,and the transport coefficient model is ?=K/CP=ρD=7.0×10?5T 0.7 g(cm s)?1.By using current models and the reference model to simulate steady Zeldovich-von Neumann-Doering(ZND) wave and free-propagating laminar flame,it is found that the results are well agreeable.Additionally,deflagration-to-detonation transition in an obstructed channel was also simulated.The numerical results are also well consistent with the experimental results.These provide a reasonable proof for current method and new models.
基金supported by the Basic Research Program of Northwestern Polytechnical University (Grant No. JC201219)the Postdoctoral Science Foundation of China (Grant No. 20100481368)
文摘A method of unstructured dynamic overset grids is developed for the numerical simulation of helicopter unsteady rotorairframe aerodynamic interaction.For the effective treatment of the relative motion between the rotor and the airframe,the domain of flowfield is divided into two overset subzones,namely,a rotational subzone containing the blades and a stationary subzone containing the airframe.The overset part of two subzones is used to convect the flow variables of the two zones.The Taylor series expansion is used to obtain a second-order spatial accuracy,and dual-time stepping is adopted to improve the solution accuracy.Mesh deformation from the blade motion in forward flight is treated by using a spring analogy.Validation is made by numerically simulating the flows around a wind tunnel configuration and comparing the predicted time-averaged and instantaneous inflow and airframe surface pressure distributions with the experimental data.It shows that the present method is efficient and robust for the prediction of complicated unsteady rotor-airframe aerodynamic interaction phenomena.
文摘Five windows such as white glass,Low-E glasses and intelligent glasses are employed for simulation of heating and cooling energy consumptions in five typical cities of China by the software TRNSYS 16.The result shows that it is the most energy saving for the doubled glass when the VO 2 films are deposited on the inside surface of the outer pane.And it is 84.7% of energy saving compared with white glass.But the heating energy consumption is the highest.This is because the transition temperature of real intelligent glass is too high and the solar heat gain coefficient is very small when the glass is in the cold state.On this basis,the property of intelligent glass is improved from the theoretical level.The result shows that it can be the most effective way of energy saving when emissivity is 0,solar transmittance is 100% in the cold state;visible light transmittance is 100%,infrared and ultraviolet light transmission rate is 0 in the hot state.Because of the technology limitation,it is hard to lower the transition temperature to below 20℃.The transition temperature of the film should be lower and the emissivity higher as far as possible.
文摘Objective To observe the efficacy of mild moxibustion combined with arthroscopic meniscal repair in the treatment of meniscal injury and to explore its action mechanism.Methods Ninety-eight patients with meniscal injury were divided into a surgery group and a moxibustion plus surgery group by the random number table method,with 49 cases in each group.Both groups received arthroscopic meniscal repair,and the moxibustion plus surgery group was treated with add-on mild moxibustion.The Lysholm score,visual analog scale(VAS)score,and mobility of the affected knee were measured before and after treatment,and transforming growth factor(TGF)-β1 and platelet-derived growth factor(PDGF)levels were measured in the fluid of the affected knee joint.The healing of the meniscus was recorded at a follow-up visit 3 months after the surgery.Results After treatment,the Lysholm score increased,the VAS score decreased in both groups,and the intra-group differences in both groups were statistically significant(P<0.05).The Lysholm score was higher in the moxibustion plus surgery group than in the surgery group,and the VAS score was lower in the moxibustion plus surgery group than in the surgery group.The differences between groups in both scores were statistically significant(P<0.05).The mobility of the affected knee joint increased in both groups(P<0.05),and it was greater in the moxibustion plus surgery group than in the surgery group(P<0.05).When compared with pretreatment,the levels of TGF-β1 and PDGF in the fluid of the knee joint increased in both groups(P<0.05),and the levels of TGF-β1 and PDGF in the fluid of the affected knee joint were higher in the moxibustion plus surgery group than in the surgery group(P<0.05).The healing of the meniscus in the moxibustion plus surgery group was significantly better than that in the surgery group at the follow-up visit 3 months after the surgery(P<0.05).Conclusion The effect of mild moxibustion combined with arthroscopic meniscal repair is better than the surgery alone in improving knee function,relieving pain,increasing mobility of the affected knee,and promoting meniscal healing,which may be related to the up-regulation of TGF-β1 and PDGF levels in the fluid of knee joint.
