Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical capacity.Toward the broader implementation,the primary obstacle lies in the intricate multi-elec...Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical capacity.Toward the broader implementation,the primary obstacle lies in the intricate multi-electron,multi-step redox reaction associated with sluggish conversion kinetics,subsequently giving rise to a cascade of parasitic issues.In order to smooth reaction kinetics,catalysts are widely introduced to accelerate reaction rate via modulating the energy barrier.Over past decades,a large amount of research has been devoted to the catalyst design and catalytic mechanism exploration,and thus the great progress in electrochemical performance has been realized.Therefore,it is necessary to make a comprehensive review toward key progress in catalyst design and future development pathway.In this review,the basic mechanism of lithium metal batteries is provided along with corresponding advantages and existing challenges detailly described.The main catalysts employed to accelerate cathode reaction with emphasis on their catalytic mechanism are summarized as well.Finally,the rational design and innovative direction toward efficient catalysts are suggested for future application in metal-sulfur/gas battery and beyond.This review is expected to drive and benefit future research on rational catalyst design with multi-parameter synergistic impacts on the activity and stability of next-generation metal battery,thus opening new avenue for sustainable solution to climate change,energy and environmental issues,and the potential industrial economy.展开更多
The homogeneous and heterogeneous reactions in the boundary-layer of a flat surface are considered. The autocatalysts are assumed to be of regular sizes, while the solution is a dilute nanofluid. The heat release due ...The homogeneous and heterogeneous reactions in the boundary-layer of a flat surface are considered. The autocatalysts are assumed to be of regular sizes, while the solution is a dilute nanofluid. The heat release due to the chemical reactions is taken into account. The Buongiorno’s model is used to describe the behaviors of this reaction system. This configuration makes the current model be different from all previous publications. Multiple solutions are given numerically to the rescaled nonlinear system, whose stability is verified. The results show that the strength coefficients of the homogeneous and heterogeneous reactions are key factors to cause the appearance of the multiple solutions in the distribution of the chemical reactions. Nanofluids enhance the diffusion of heat and help maintain the stability of chemical reactions.展开更多
This article addresses melting heat transfer in magnetohydrodynamics(MHD)nanofluid flows by a rotating disk. The analysis is performed in Cu-water and Ag-water nanofluids. Thermal radiation, viscous dissipation, and c...This article addresses melting heat transfer in magnetohydrodynamics(MHD)nanofluid flows by a rotating disk. The analysis is performed in Cu-water and Ag-water nanofluids. Thermal radiation, viscous dissipation, and chemical reactions impacts are added in the nanofluid model. Appropriate transformations lead to the nondimensionalized boundary layer equations. Series solutions for the resulting equations are computed.The role of pertinent parameters on the velocity, temperature, and concentration is analyzed in the outputs. It is revealed that the larger melting parameter enhances the velocity profile while the temperature profile decreases. The surface drag force and heat transfer rate are computed under the influence of pertinent parameters. Furthermore, the homogeneous reaction parameter serves to decrease the surface concentration.展开更多
The steady two-dimensional flow of Powell-Eyring fluid is investigated. The flow is caused by a stretching surface with homogeneous-heterogeneous reactions. The governing nonlinear differential equations are reduced t...The steady two-dimensional flow of Powell-Eyring fluid is investigated. The flow is caused by a stretching surface with homogeneous-heterogeneous reactions. The governing nonlinear differential equations are reduced to the ordinary differential equations by similarity transformations. The analytic solutions are presented in series forms by homotopy analysis method(HAM). Convergence of the obtained series solutions is explicitly discussed. The physical significance of different parameters on the velocity and concentration profiles is discussed through graphical illustrations. It is noticed that the boundary layer thickness increases by increasing the Powell-Eyring fluid material parameter(ε) whereas it decreases by increasing the fluid material parameter(δ). Further, the concentration profile increases when Powell-Eyring fluid material parameters increase. The concentration is also an increasing function of Schmidt number and decreasing function of strength of homogeneous reaction. Also mass transfer rate increases for larger rate of heterogeneous reaction.展开更多
This letter describes the characteristics of homogeneous-heterogeneous re- action in the boundary layer flow of a Jeffrey fluid due to an impermeable horizontal stretching sheet. An analysis is carried out through the...This letter describes the characteristics of homogeneous-heterogeneous re- action in the boundary layer flow of a Jeffrey fluid due to an impermeable horizontal stretching sheet. An analysis is carried out through the similar values of reactant and auto catalyst diffusion coefficients. Heat released by the reaction is not accounted. The exact solution for the flow of the Jeffrey fluid is constructed. The series solution for the concentration equation is derived. The velocity and concentration fields reflecting the impact of interesting parameters are plotted and examined.展开更多
This study deals with the stagnation point flow of ferrofluid over a flat plate with non-linear slip boundary condition in the presence of homogeneous-heterogeneous reactions.Three kinds of ferroparticles,namely,magne...This study deals with the stagnation point flow of ferrofluid over a flat plate with non-linear slip boundary condition in the presence of homogeneous-heterogeneous reactions.Three kinds of ferroparticles,namely,magnetite(Fe_3O_4),cobalt ferrite(CoFe_2O_4) and manganese zinc ferrite(Mn-ZnFe_2O_4) are taken into account with water and kerosene as conventional base fluids.The developed model of homogeneous-heterogeneous reactions in boundary layer flow with equal and unequal diffusivities for reactant and autocatalysis is considered.The governing partial differential equations are converted into system of non-linear ordinary differential equations by mean of similarity transformations.These ordinary differential equations are integrated numerically using shooting method.The effects of pertinent parameters on velocity and concentration profiles are presented graphically and discussed.We found that in the presence of Fe_3O_4-kerosene and CoFe_2O_4-kerosene,velocity profiles increase for large values of α and β whereas there is a decrement in concentration profiles with increasing values of if and K_s.Furthermore,the comparison between non-magnetic(A1_2O_3) and magnetic Fe_3O_4 nanoparticles is given in tabular form.展开更多
In this paper,a typical experiment is carried out based on a high-resolution air-sea coupled model,namely,the coupled ocean-atmosphere-wave-sediment transport(COAWST)model,on both heterogeneous many-core(SW)and homoge...In this paper,a typical experiment is carried out based on a high-resolution air-sea coupled model,namely,the coupled ocean-atmosphere-wave-sediment transport(COAWST)model,on both heterogeneous many-core(SW)and homogenous multicore(Intel)supercomputing platforms.We construct a hindcast of Typhoon Lekima on both the SW and Intel platforms,compare the simulation results between these two platforms and compare the key elements of the atmospheric and ocean modules to reanalysis data.The comparative experiment in this typhoon case indicates that the domestic many-core computing platform and general cluster yield almost no differences in the simulated typhoon path and intensity,and the differences in surface pressure(PSFC)in the WRF model and sea surface temperature(SST)in the short-range forecast are very small,whereas a major difference can be identified at high latitudes after the first 10 days.Further heat budget analysis verifies that the differences in SST after 10 days are mainly caused by shortwave radiation variations,as influenced by subsequently generated typhoons in the system.These typhoons generated in the hindcast after the first 10 days attain obviously different trajectories between the two platforms.展开更多
In this study,high-gravity intensified heterogeneous catalytic ozonation is utilized for treatment of phenol-containing wastewater,and the kinetics of the direct reaction between ozone and phenol in the presence of ex...In this study,high-gravity intensified heterogeneous catalytic ozonation is utilized for treatment of phenol-containing wastewater,and the kinetics of the direct reaction between ozone and phenol in the presence of excess tertiary butanol(TBA)is investigated.It is revealed that the direct reaction between ozone and phenol in the rotating packed bed(RPB)follows the pseudo-first-order kinetics with a reaction rate constant higher than that in the conventional bubbling reactor(BR).Under different conditions of temperature,initial pH,high-gravity factor,and gaseous ozone concentration,the apparent reaction rate constant varies in the range of 0.0160–0.115 min-1.An empirical power-exponential model is established to characterize the effects of these parameters on the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation.展开更多
Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch ...Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch procedure and continuous-flow procedure) were used to study the variations of reaction processing. The heterogeneous catalysts presented excellent reactivity and recyclability for iodobenzene and bromobenzene substrates in batch mode, which can be attributed to stabilization of Pd nanoparticles by the thiol and amino groups on the AC supports. However, significant dehalogenation in the reaction mixture and Pd leaching from the heterogeneous catalysts were observed in continuous-flow mode.This unique phenomenon in continuous-flow mode resulted in a dramatic decline in reaction selectivity and durability of heterogeneous catalysts comparing with that of batch mode. In addition, the heterogeneous Pd catalysts with thiol-and amino-modified AC supports exhibited different reactivity and durability in batch and continuous-flow mode owing to the difference of interaction between Pd species and AC supports.展开更多
Aimed at the problem of unbalanced energy existed in sensor networks, the clustered method is employed to enhance the efficient utilization of limited energy resources of the deployed sensor nodes. In this paper, we d...Aimed at the problem of unbalanced energy existed in sensor networks, the clustered method is employed to enhance the efficient utilization of limited energy resources of the deployed sensor nodes. In this paper, we describe the network lifetime as a function of the communication and data aggregation energy consumption and analyze the lifetime of different transmission schemes in the homogeneous and heterogeneous sensor networks. The analysis carried out in this paper can provide the guidelines for network deployment and protocol design in the future applications.展开更多
Based on thermal analysis, the isothermal and nonisothemal crystallization kinetics of Ziegler-Natta catalyzed linear low density polyethylene (Z-N LLDPE) and metallocene catalyzed LLDPE (m-LLDPE) were studied. Treati...Based on thermal analysis, the isothermal and nonisothemal crystallization kinetics of Ziegler-Natta catalyzed linear low density polyethylene (Z-N LLDPE) and metallocene catalyzed LLDPE (m-LLDPE) were studied. Treating the results with the Avrami equation and the Ozawa equation, the crystallization constant Igk and the Avrami exponent n were obtained. Some other crystallization parameters were also discussed. According to the different characteristics of the chain structures of Z-N LLDPE and metallocene LLDPE, their crystallization behaviors were analyzed. It is indicated that the homogeneity and heterogeneity of the two polymers act in different way during the crystallization process of polymers, including the nucleation and the growth of crystals under various conditions.展开更多
The air quality model CMAQ-MADRID (Community Multiscale Air Quality-Model of Aerosol Dynamics, Reaction, Ionization and Dissolution) was employed to simulate summer O3 formation in Beijing China, in order to explore...The air quality model CMAQ-MADRID (Community Multiscale Air Quality-Model of Aerosol Dynamics, Reaction, Ionization and Dissolution) was employed to simulate summer O3 formation in Beijing China, in order to explore the impacts of four heterogeneous reactions on O3 formation in an urban area. The results showed that the impacts were obvious and exhibited the characteristics of a typical response of a VOC-limited regime in the urban area. For the four heterogeneous reactions considered, the NO2 and HO2 heterogeneous reactions have the most severe impacts on O3 formation. During the O3 formation period, the NO2 heterogeneous reaction increased new radical creation by 30%, raising the atmospheric activity as more NO→NO2 conversion occurred, thus causing the O3 to rise. The increase of O3 peak concentration reached a maximum value of 67 ppb in the urban area. In the morning hours, high NO titration reduced the effect of the photolysis of HONO, which was produced heterogeneously at night in the surface layer. The NO2 heterogeneous reaction in the daytime is likely one of the major reasons causing the O3 increase in the Beijing urban area. The HO2 heterogeneous reaction accelerated radical termination, resulting in a decrease of the radical concentration by 44% at the most. O3 peak concentration decreased by a maximum amount of 24 ppb in the urban area. The simulation results were improved when the heterogeneous reactions were included, with the O3 and HONO model results close to the observations.展开更多
An efficient three-component synthesis of 3,4-dihydropyrimidinones using MCM-41 anchored sulfonic acid (MCM-41-R-SO3H) as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is desc...An efficient three-component synthesis of 3,4-dihydropyrimidinones using MCM-41 anchored sulfonic acid (MCM-41-R-SO3H) as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is described.展开更多
The variations of sulfate formation and optical coefficients during SO2 heterogeneous reactions on hematite surface under different SO2 concentrations were examined using in situ diffuse reflectance infrared Fourier t...The variations of sulfate formation and optical coefficients during SO2 heterogeneous reactions on hematite surface under different SO2 concentrations were examined using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatograph (IC). Laboratory experiments revealed that within ambient SO2 of 0.51-18.6 ppmv, sulfate product, producing velocity, absorption and backward scattering coefficients showed an increasing trend with SO2 concentration. Under given SO2 concentration, the velocity of sulfate producing performed an evolution of initial increasing, midterm decreasing and final stabilizing. The reactive uptake and Brunaner-Emmett-Teller (BET) uptake coefficients of heterogeneous reactions rose with SOz and exhibited high reactivities. Considering global warming, this result is important for the knowledge of heterogeneous reactions of SO2 on mineral particle surface in the atmosphere and the assessment of their impacts on radiative forcing.展开更多
This paper deals with modeling of the phenomenon of fretting fatigue in heterogeneous materials using the multi-scale computational homogenization technique and finite element analysis(FEA).The heterogeneous material ...This paper deals with modeling of the phenomenon of fretting fatigue in heterogeneous materials using the multi-scale computational homogenization technique and finite element analysis(FEA).The heterogeneous material for the specimens consists of a single hole model(25% void/cell,16% void/cell and 10% void/cell)and a four-hole model(25%void/cell).Using a representative volume element(RVE),we try to produce the equivalent homogenized properties and work on a homogeneous specimen for the study of fretting fatigue.Next,the fretting fatigue contact problem is performed for 3 new cases of models that consist of a homogeneous and a heterogeneous part(single hole cell)in the contact area.The aim is to analyze the normal and shear stresses of these models and compare them with the results of the corresponding heterogeneous models based on the Direct Numerical Simulation(DNS)method.Finally,by comparing the computational time and%deviations,we draw conclusions about the reliability and effectiveness of the proposed method.展开更多
Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated th...Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was La0.62Pb0.38MnO3 and the average diameter could be about 25.4 nm. The optimum conditions for synthesis of DPC with Pd/LaxPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catMyst/phenol mass ratio 1 to 50, pressure 4.5 MPa,volume concentration of O2 25%, reaction temperature 60° and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.展开更多
Oxidized starch powder and cationic starch solution were reacted with alkyl ketene dimer(AKD) under heterogeneous conditions at 70℃ for 12 h.The AKD molecules reacted with starch hydroxyl groups to form β-keto ester...Oxidized starch powder and cationic starch solution were reacted with alkyl ketene dimer(AKD) under heterogeneous conditions at 70℃ for 12 h.The AKD molecules reacted with starch hydroxyl groups to form β-keto ester linkages under the above conditions.The reaction products were separated into CHCl_3-soluble and CHCl_3-insoluble fractions.FT-IR spectroscopy,SEM,Xray diffraction,and TG-DTA analyses of the CHCl_3-insoluble fraction indicated that β-keto ester substituents were introduced to hydroxyl groups on the starch surfaces.The results indicated that hydrogen bonds between the starch molecules were disrupted under heterogeneous conditions upon heating.The activity and accessibility of hydroxyl groups were enhanced,as a result of which β-keto ester bonds were produced between AKD and starch.Based on these results,we speculate that the β-keto esters which existed in the sheets sized by AKD emulsions were generated by the reaction between AKD and starch.展开更多
The reaction kinetics of the heterogeneous oxidation of toluene with Mn 3+ was studied by considering the effects of disproportionation of Mn 3+ in reaction system, a 'parallel' modulus was set up. A...The reaction kinetics of the heterogeneous oxidation of toluene with Mn 3+ was studied by considering the effects of disproportionation of Mn 3+ in reaction system, a 'parallel' modulus was set up. And then the concentration of Mn 3+ in disproportionation and the concentration of benzaldehyde in oxidation were respectively determined in turn, the rate constant, order and pseudo activation energy of the heterogeneous oxidation were obtained by mathematical deduction and the kinetic equation was concluded. In addition, the reaction mechanism was analyzed. It shows that the results are completely consistent with modulus.展开更多
The spatial distributions and interannual variations of aerosol concentrations,aerosol optical depth(AOD) ,aerosol direct radiative forcings,and their responses to heterogeneous reactions on dust surfaces over East As...The spatial distributions and interannual variations of aerosol concentrations,aerosol optical depth(AOD) ,aerosol direct radiative forcings,and their responses to heterogeneous reactions on dust surfaces over East Asia in March 2006-10 were investigated by utilizing a regional coupled climate-chemistry/aerosol model. Anthropogenic aerosol concentrations(inorganic+carbonaceous) were higher in March 2006 and 2008,whereas soil dust reached its highest levels in March 2006 and 2010,resulting in stronger aerosol radiative forcings in these periods.The domain and five-year(2006-10) monthly mean concentrations of anthropogenic and dust aerosols,AOD,and radiative forcings at the surface(SURF) and at the top of the atmosphere(TOA) in March were 2.4μg m-3,13.1μg m-3,0.18,-19.0 W m-2,and-7.4 W m-2,respectively.Heterogeneous reactions led to an increase of total inorganic aerosol concentration;however,the ambient inorganic aerosol concentration decreased,resulting in a smaller AOD and weaker aerosol radiative forcings.In March 2006 and 2010,the changes in ambient inorganic aerosols,AOD,and aerosol radiative forcings were more evident.In terms of the domain and five-year averages,the total inorganic aerosol concentrations increased by 13.7%(0.17μg m-3) due to heterogeneous reactions,but the ambient inorganic aerosol concentrations were reduced by 10.5%(0.13μg m-3) .As a result,the changes in AOD,SURF and TOA radiative forcings were estimated to be-3.9%(-0.007) ,-1.7%(0.34 W m-2) ,and-4.3%(0.34 W m-2) ,respectively,in March over East Asia.展开更多
基金supported by the National Natural Science Foundation of China(52272194)Liaoning Revitalization Talents Program(XLYC2007155)。
文摘Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical capacity.Toward the broader implementation,the primary obstacle lies in the intricate multi-electron,multi-step redox reaction associated with sluggish conversion kinetics,subsequently giving rise to a cascade of parasitic issues.In order to smooth reaction kinetics,catalysts are widely introduced to accelerate reaction rate via modulating the energy barrier.Over past decades,a large amount of research has been devoted to the catalyst design and catalytic mechanism exploration,and thus the great progress in electrochemical performance has been realized.Therefore,it is necessary to make a comprehensive review toward key progress in catalyst design and future development pathway.In this review,the basic mechanism of lithium metal batteries is provided along with corresponding advantages and existing challenges detailly described.The main catalysts employed to accelerate cathode reaction with emphasis on their catalytic mechanism are summarized as well.Finally,the rational design and innovative direction toward efficient catalysts are suggested for future application in metal-sulfur/gas battery and beyond.This review is expected to drive and benefit future research on rational catalyst design with multi-parameter synergistic impacts on the activity and stability of next-generation metal battery,thus opening new avenue for sustainable solution to climate change,energy and environmental issues,and the potential industrial economy.
基金the National Natural Science Foundation of China(Nos.11872241 and11432009)。
文摘The homogeneous and heterogeneous reactions in the boundary-layer of a flat surface are considered. The autocatalysts are assumed to be of regular sizes, while the solution is a dilute nanofluid. The heat release due to the chemical reactions is taken into account. The Buongiorno’s model is used to describe the behaviors of this reaction system. This configuration makes the current model be different from all previous publications. Multiple solutions are given numerically to the rescaled nonlinear system, whose stability is verified. The results show that the strength coefficients of the homogeneous and heterogeneous reactions are key factors to cause the appearance of the multiple solutions in the distribution of the chemical reactions. Nanofluids enhance the diffusion of heat and help maintain the stability of chemical reactions.
文摘This article addresses melting heat transfer in magnetohydrodynamics(MHD)nanofluid flows by a rotating disk. The analysis is performed in Cu-water and Ag-water nanofluids. Thermal radiation, viscous dissipation, and chemical reactions impacts are added in the nanofluid model. Appropriate transformations lead to the nondimensionalized boundary layer equations. Series solutions for the resulting equations are computed.The role of pertinent parameters on the velocity, temperature, and concentration is analyzed in the outputs. It is revealed that the larger melting parameter enhances the velocity profile while the temperature profile decreases. The surface drag force and heat transfer rate are computed under the influence of pertinent parameters. Furthermore, the homogeneous reaction parameter serves to decrease the surface concentration.
文摘The steady two-dimensional flow of Powell-Eyring fluid is investigated. The flow is caused by a stretching surface with homogeneous-heterogeneous reactions. The governing nonlinear differential equations are reduced to the ordinary differential equations by similarity transformations. The analytic solutions are presented in series forms by homotopy analysis method(HAM). Convergence of the obtained series solutions is explicitly discussed. The physical significance of different parameters on the velocity and concentration profiles is discussed through graphical illustrations. It is noticed that the boundary layer thickness increases by increasing the Powell-Eyring fluid material parameter(ε) whereas it decreases by increasing the fluid material parameter(δ). Further, the concentration profile increases when Powell-Eyring fluid material parameters increase. The concentration is also an increasing function of Schmidt number and decreasing function of strength of homogeneous reaction. Also mass transfer rate increases for larger rate of heterogeneous reaction.
文摘This letter describes the characteristics of homogeneous-heterogeneous re- action in the boundary layer flow of a Jeffrey fluid due to an impermeable horizontal stretching sheet. An analysis is carried out through the similar values of reactant and auto catalyst diffusion coefficients. Heat released by the reaction is not accounted. The exact solution for the flow of the Jeffrey fluid is constructed. The series solution for the concentration equation is derived. The velocity and concentration fields reflecting the impact of interesting parameters are plotted and examined.
文摘This study deals with the stagnation point flow of ferrofluid over a flat plate with non-linear slip boundary condition in the presence of homogeneous-heterogeneous reactions.Three kinds of ferroparticles,namely,magnetite(Fe_3O_4),cobalt ferrite(CoFe_2O_4) and manganese zinc ferrite(Mn-ZnFe_2O_4) are taken into account with water and kerosene as conventional base fluids.The developed model of homogeneous-heterogeneous reactions in boundary layer flow with equal and unequal diffusivities for reactant and autocatalysis is considered.The governing partial differential equations are converted into system of non-linear ordinary differential equations by mean of similarity transformations.These ordinary differential equations are integrated numerically using shooting method.The effects of pertinent parameters on velocity and concentration profiles are presented graphically and discussed.We found that in the presence of Fe_3O_4-kerosene and CoFe_2O_4-kerosene,velocity profiles increase for large values of α and β whereas there is a decrement in concentration profiles with increasing values of if and K_s.Furthermore,the comparison between non-magnetic(A1_2O_3) and magnetic Fe_3O_4 nanoparticles is given in tabular form.
基金This work is supported by the National Key Research and Development Plan program of the Ministry of Science and Technology of China(No.2016YFB0201100)Additionally,this work is supported by the National Laboratory for Marine Science and Technology(Qingdao)Major Project of the Aoshan Science and Technology Innovation Program(No.2018ASKJ01-04)the Open Fundation of Key Laboratory of Marine Science and Numerical Simulation,Ministry of Natural Resources(No.2021-YB-02).
文摘In this paper,a typical experiment is carried out based on a high-resolution air-sea coupled model,namely,the coupled ocean-atmosphere-wave-sediment transport(COAWST)model,on both heterogeneous many-core(SW)and homogenous multicore(Intel)supercomputing platforms.We construct a hindcast of Typhoon Lekima on both the SW and Intel platforms,compare the simulation results between these two platforms and compare the key elements of the atmospheric and ocean modules to reanalysis data.The comparative experiment in this typhoon case indicates that the domestic many-core computing platform and general cluster yield almost no differences in the simulated typhoon path and intensity,and the differences in surface pressure(PSFC)in the WRF model and sea surface temperature(SST)in the short-range forecast are very small,whereas a major difference can be identified at high latitudes after the first 10 days.Further heat budget analysis verifies that the differences in SST after 10 days are mainly caused by shortwave radiation variations,as influenced by subsequently generated typhoons in the system.These typhoons generated in the hindcast after the first 10 days attain obviously different trajectories between the two platforms.
基金supported by the Fund for Shanxi Province Higher Education“1331 Project”for Improving Quality and Efficiency Construction(nuc2021-006)Key Research&Development Plan of Shanxi Province(201903D321059)+1 种基金Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20200004)Transformation and Cultivation Projects of Scientific and Technological Achievements in Universities of Shanxi Province Institutions(2020CG040).
文摘In this study,high-gravity intensified heterogeneous catalytic ozonation is utilized for treatment of phenol-containing wastewater,and the kinetics of the direct reaction between ozone and phenol in the presence of excess tertiary butanol(TBA)is investigated.It is revealed that the direct reaction between ozone and phenol in the rotating packed bed(RPB)follows the pseudo-first-order kinetics with a reaction rate constant higher than that in the conventional bubbling reactor(BR).Under different conditions of temperature,initial pH,high-gravity factor,and gaseous ozone concentration,the apparent reaction rate constant varies in the range of 0.0160–0.115 min-1.An empirical power-exponential model is established to characterize the effects of these parameters on the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation.
基金the support of the National Natural Science Foundation of China (20222809, 21978146)TsinghuaFoshan Innovation Special Fund (2021THFS0214)。
文摘Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch procedure and continuous-flow procedure) were used to study the variations of reaction processing. The heterogeneous catalysts presented excellent reactivity and recyclability for iodobenzene and bromobenzene substrates in batch mode, which can be attributed to stabilization of Pd nanoparticles by the thiol and amino groups on the AC supports. However, significant dehalogenation in the reaction mixture and Pd leaching from the heterogeneous catalysts were observed in continuous-flow mode.This unique phenomenon in continuous-flow mode resulted in a dramatic decline in reaction selectivity and durability of heterogeneous catalysts comparing with that of batch mode. In addition, the heterogeneous Pd catalysts with thiol-and amino-modified AC supports exhibited different reactivity and durability in batch and continuous-flow mode owing to the difference of interaction between Pd species and AC supports.
基金Sponsored by the Shanghai Leading Academic Discipline Project (Grant No.S30108 and 08DZ2231100)Shanghai Education Committee (Grant No.09YZ33)+1 种基金Shanghai Science Committee(Grant No.08220510900)Key Lab Fund of SIMIT
文摘Aimed at the problem of unbalanced energy existed in sensor networks, the clustered method is employed to enhance the efficient utilization of limited energy resources of the deployed sensor nodes. In this paper, we describe the network lifetime as a function of the communication and data aggregation energy consumption and analyze the lifetime of different transmission schemes in the homogeneous and heterogeneous sensor networks. The analysis carried out in this paper can provide the guidelines for network deployment and protocol design in the future applications.
基金This work was supported by the National Natural Science Foundation of China (No. B040504), and the Science Foundation of State Key Laboratory of Polymer Physics and Chemistry, Chinese Academy of Sciences (00-B-15).
文摘Based on thermal analysis, the isothermal and nonisothemal crystallization kinetics of Ziegler-Natta catalyzed linear low density polyethylene (Z-N LLDPE) and metallocene catalyzed LLDPE (m-LLDPE) were studied. Treating the results with the Avrami equation and the Ozawa equation, the crystallization constant Igk and the Avrami exponent n were obtained. Some other crystallization parameters were also discussed. According to the different characteristics of the chain structures of Z-N LLDPE and metallocene LLDPE, their crystallization behaviors were analyzed. It is indicated that the homogeneity and heterogeneity of the two polymers act in different way during the crystallization process of polymers, including the nucleation and the growth of crystals under various conditions.
文摘The air quality model CMAQ-MADRID (Community Multiscale Air Quality-Model of Aerosol Dynamics, Reaction, Ionization and Dissolution) was employed to simulate summer O3 formation in Beijing China, in order to explore the impacts of four heterogeneous reactions on O3 formation in an urban area. The results showed that the impacts were obvious and exhibited the characteristics of a typical response of a VOC-limited regime in the urban area. For the four heterogeneous reactions considered, the NO2 and HO2 heterogeneous reactions have the most severe impacts on O3 formation. During the O3 formation period, the NO2 heterogeneous reaction increased new radical creation by 30%, raising the atmospheric activity as more NO→NO2 conversion occurred, thus causing the O3 to rise. The increase of O3 peak concentration reached a maximum value of 67 ppb in the urban area. In the morning hours, high NO titration reduced the effect of the photolysis of HONO, which was produced heterogeneously at night in the surface layer. The NO2 heterogeneous reaction in the daytime is likely one of the major reasons causing the O3 increase in the Beijing urban area. The HO2 heterogeneous reaction accelerated radical termination, resulting in a decrease of the radical concentration by 44% at the most. O3 peak concentration decreased by a maximum amount of 24 ppb in the urban area. The simulation results were improved when the heterogeneous reactions were included, with the O3 and HONO model results close to the observations.
文摘An efficient three-component synthesis of 3,4-dihydropyrimidinones using MCM-41 anchored sulfonic acid (MCM-41-R-SO3H) as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is described.
基金supported by the National Natural Science Foundation of China (No. 40533017, 20377008,40605001)the National Key Technology R&D Program(No. 2006BAC12B001)the State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC-KF-2006-05) of China
文摘The variations of sulfate formation and optical coefficients during SO2 heterogeneous reactions on hematite surface under different SO2 concentrations were examined using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatograph (IC). Laboratory experiments revealed that within ambient SO2 of 0.51-18.6 ppmv, sulfate product, producing velocity, absorption and backward scattering coefficients showed an increasing trend with SO2 concentration. Under given SO2 concentration, the velocity of sulfate producing performed an evolution of initial increasing, midterm decreasing and final stabilizing. The reactive uptake and Brunaner-Emmett-Teller (BET) uptake coefficients of heterogeneous reactions rose with SOz and exhibited high reactivities. Considering global warming, this result is important for the knowledge of heterogeneous reactions of SO2 on mineral particle surface in the atmosphere and the assessment of their impacts on radiative forcing.
文摘This paper deals with modeling of the phenomenon of fretting fatigue in heterogeneous materials using the multi-scale computational homogenization technique and finite element analysis(FEA).The heterogeneous material for the specimens consists of a single hole model(25% void/cell,16% void/cell and 10% void/cell)and a four-hole model(25%void/cell).Using a representative volume element(RVE),we try to produce the equivalent homogenized properties and work on a homogeneous specimen for the study of fretting fatigue.Next,the fretting fatigue contact problem is performed for 3 new cases of models that consist of a homogeneous and a heterogeneous part(single hole cell)in the contact area.The aim is to analyze the normal and shear stresses of these models and compare them with the results of the corresponding heterogeneous models based on the Direct Numerical Simulation(DNS)method.Finally,by comparing the computational time and%deviations,we draw conclusions about the reliability and effectiveness of the proposed method.
基金National Natural Science Foundation of China(No.20076036Tianjin University C1 National Laboratory Project
文摘Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was La0.62Pb0.38MnO3 and the average diameter could be about 25.4 nm. The optimum conditions for synthesis of DPC with Pd/LaxPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catMyst/phenol mass ratio 1 to 50, pressure 4.5 MPa,volume concentration of O2 25%, reaction temperature 60° and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.
基金financial support from Shandong Province Education Department(Grant No.J14 LC11)National Natural Science Foundation of China(Grant No.21406126 and 21576146)+2 种基金Department of Science and Technology of Shandong Province(Grant No.2014 GSF116001)973(Grant No.2014 CB460610)Department of Science and Technology of Shandong Province(Grant No.2015 ZDXX0403 B03)
文摘Oxidized starch powder and cationic starch solution were reacted with alkyl ketene dimer(AKD) under heterogeneous conditions at 70℃ for 12 h.The AKD molecules reacted with starch hydroxyl groups to form β-keto ester linkages under the above conditions.The reaction products were separated into CHCl_3-soluble and CHCl_3-insoluble fractions.FT-IR spectroscopy,SEM,Xray diffraction,and TG-DTA analyses of the CHCl_3-insoluble fraction indicated that β-keto ester substituents were introduced to hydroxyl groups on the starch surfaces.The results indicated that hydrogen bonds between the starch molecules were disrupted under heterogeneous conditions upon heating.The activity and accessibility of hydroxyl groups were enhanced,as a result of which β-keto ester bonds were produced between AKD and starch.Based on these results,we speculate that the β-keto esters which existed in the sheets sized by AKD emulsions were generated by the reaction between AKD and starch.
文摘The reaction kinetics of the heterogeneous oxidation of toluene with Mn 3+ was studied by considering the effects of disproportionation of Mn 3+ in reaction system, a 'parallel' modulus was set up. And then the concentration of Mn 3+ in disproportionation and the concentration of benzaldehyde in oxidation were respectively determined in turn, the rate constant, order and pseudo activation energy of the heterogeneous oxidation were obtained by mathematical deduction and the kinetic equation was concluded. In addition, the reaction mechanism was analyzed. It shows that the results are completely consistent with modulus.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No. KZCX2-YW-Q11-03)the National Basic Research Program of China(Grant No.2010CB950804)100 Talents Program of the Chinese Academy of Sciences
文摘The spatial distributions and interannual variations of aerosol concentrations,aerosol optical depth(AOD) ,aerosol direct radiative forcings,and their responses to heterogeneous reactions on dust surfaces over East Asia in March 2006-10 were investigated by utilizing a regional coupled climate-chemistry/aerosol model. Anthropogenic aerosol concentrations(inorganic+carbonaceous) were higher in March 2006 and 2008,whereas soil dust reached its highest levels in March 2006 and 2010,resulting in stronger aerosol radiative forcings in these periods.The domain and five-year(2006-10) monthly mean concentrations of anthropogenic and dust aerosols,AOD,and radiative forcings at the surface(SURF) and at the top of the atmosphere(TOA) in March were 2.4μg m-3,13.1μg m-3,0.18,-19.0 W m-2,and-7.4 W m-2,respectively.Heterogeneous reactions led to an increase of total inorganic aerosol concentration;however,the ambient inorganic aerosol concentration decreased,resulting in a smaller AOD and weaker aerosol radiative forcings.In March 2006 and 2010,the changes in ambient inorganic aerosols,AOD,and aerosol radiative forcings were more evident.In terms of the domain and five-year averages,the total inorganic aerosol concentrations increased by 13.7%(0.17μg m-3) due to heterogeneous reactions,but the ambient inorganic aerosol concentrations were reduced by 10.5%(0.13μg m-3) .As a result,the changes in AOD,SURF and TOA radiative forcings were estimated to be-3.9%(-0.007) ,-1.7%(0.34 W m-2) ,and-4.3%(0.34 W m-2) ,respectively,in March over East Asia.