The pyrolysis of cyclohexane,methylcyclohexane,and ethylcyclohexane have been studied behind reflected shock waves at pressures of 5 and10 bar and at temperatures of 930-1550 K for 0.05%fuel diluted by Argon.A single-...The pyrolysis of cyclohexane,methylcyclohexane,and ethylcyclohexane have been studied behind reflected shock waves at pressures of 5 and10 bar and at temperatures of 930-1550 K for 0.05%fuel diluted by Argon.A single-pulse shock tube(SPST)is used to perform the pyrolysis experiments at reaction times varying from 1.65 to 1.74 ms.Major products are obtained and quantified using gas chromatography analysis.A flame ionization detector and a thermal conductivity detector are used for species identification and quantification.Kinetic modeling has been performed using several detailed and lumped chemical kinetic mechanisms.Differences in modeling results among the kinetic models are described.Reaction path analysis and sensitivity analysis are performed to determine the important reactions controlling fuel pyrolysis and their influence on the predicted concentrations of reactant and product species profiles.The present work provides new fundamental knowledge in understating pyrolysis characteristics of cyclohexane compounds and additional data set for detailed kinetic mechanism development.展开更多
The ethylene aromatization is critical for the methanol to aromatics and light alkane dehydroaromatization process.The single-event microkinetic(SEMK)model combining the linear free energy theory and solid acid distri...The ethylene aromatization is critical for the methanol to aromatics and light alkane dehydroaromatization process.The single-event microkinetic(SEMK)model combining the linear free energy theory and solid acid distribution concept were established and extend for the ethylene aromatization process,which can reduce the kinetic parameters and simplify the reaction network by comparison with the SEMK model including subtype elementary steps based on the type of carbenium ions.Further introducing deactivation parametersφinto the model and applying the linear free energy model to the deactivation experimental data,the obtained deactivation parametersφindicate that the carbon deposition precursors have the greatest impact on reducing the reaction rate of single-molecular reactions and the smallest impact on the hydrogen transfer reaction.Meanwhile,according to the change of reaction enthalpy,effect of carbenium ion structure on methylation,ethylation,cyclization and endo-βscission was investigated by introducing linear free energy concept into the SEMK model.The effect of different acid strengths on elementary steps was investigated based on the acid strength distribution model,it was found that the methylation and oligomerization reactions,the ali-βscission reaction,endo-βscission reaction and the cyclization reaction were more sensitive to strong acidity sites.The physisorption and chemisorption heat are separated from the protonation heat in the linear free energy kinetic model and the acid strength distribution kinetic model,and the absolute values of the obtained physisorption and chemisorption heat increase with the carbon number of carbenium ions.Furthermore,the parameters of the acid strength distribution kinetic model were applied to propane dehydroaromatization on H-ZSM-5 and the ethane dehydroaromatization on Zn/ZSM-5 to confirm the independence of parameters in the SEMK model with the similar reaction network.展开更多
It is commonly accepted that, on social networks, the opinion of the agents with a higher connectivity, i.e., a larger number of followers, results in more convincing than that of the agents with a lower number of fol...It is commonly accepted that, on social networks, the opinion of the agents with a higher connectivity, i.e., a larger number of followers, results in more convincing than that of the agents with a lower number of followers. By kinetic modeling approach, a kinetic model of opinion formation on social networks is derived, in which the distribution function depends on both the opinion and the connectivity of the agents. The opinion exchange process is governed by a Sznajd type model with three opinions, ±1, 0, and the social network is represented statistically with connectivity denoting the number of contacts of a given individual. The asymptotic mean opinion of a social network is determined in terms of the initial opinion and the connectivity of the agents.展开更多
In order to investigate the hydrofining process of LCO for producing aromatics and gasoline,the selective hydrogenation of polycyclic aromatic hydrocarbons(PAHs),a major component of light cycle oil(LCO),was studied u...In order to investigate the hydrofining process of LCO for producing aromatics and gasoline,the selective hydrogenation of polycyclic aromatic hydrocarbons(PAHs),a major component of light cycle oil(LCO),was studied using a NiMoW/Al_(2)O_(3)catalyst.Based on the study of the reversible hydrogenation reaction,PAHs in the selective hydrogenation process could be effectively simulated by the modeled CH and CH_(2) groups,and the hydrodesulfurization and hydrodenitrogenation kinetic models could be further established in this process.The results showed that the kinetic models developed could fit the experimental data effectively and predict the content of S,N,and aromatics in the selective hydrogenation products of LCO.展开更多
Gamma-aminobutyric acid(GABA)is a natural non-protein functio nal amino acid,which has potential for fermentation industrial production by Lactobacillus brevis.This work investigated the batch fermentation process and...Gamma-aminobutyric acid(GABA)is a natural non-protein functio nal amino acid,which has potential for fermentation industrial production by Lactobacillus brevis.This work investigated the batch fermentation process and developed a kinetic model based on substrate restrictive model established by experimental data from L25(5~6)orthogonal experiments.In this study,the OD600 value of fermentation broth was fixed to constant after reaching its maximum because the microorganism death showed no effect on the enzyme activity of glutamate decarboxylase(GAD).As pH is one of the key parameters in fermentation process,a pH-dependent kinetic model based on radial basis function was developed to enhance the practicality of the model.Furthermore,as to decrease the deviations between the simulated curves and the experimental data,the rolling correction strategy with OD600 values that was measured in real-time was introduced into this work to modify the model.Finally,the accu racy of the rolling corrected and pH-dependent model was validated by good fitness between the simulated curves and data of the initial batch fermentation(pH 5.2).As a result,this pH-dependent kinetic model revealed that the optimal pH for biomass growth is 5.6-5.7 and for GABA production is about 5,respectively.Therefore,the developed model is practical and convenient for the instruction of GABA fermentation production,and it has instructive significance for the industrial scale.展开更多
Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumet...Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumetric oxygen mass transfer coefficient(k_(L)a)and gas holdup,as well as improve the bioprocess in a bioreactor.In this study,we compared mass transfer,gas holdup,and batch and con-tinuous fermentation for RNA production in CCAB and RDMAB.In addition,unstructured kinetic models for microbial growth,substrate utilization,and RNA formation were established.In batch fermentation,biomass,RNA yield,and substrate utilization in the RDMAB were higher than those in the CCAB,which indicates that dynamic membrane aeration produced a high k_(L)a by fine bubbles;a higher k_(L)a is more bene-ficial to aerobic fermentation.The starting time of continuous fermentation in the RDMAB was 20 h ear-lier than that in the CCAB,which greatly improved the biological process.During continuous fermentation,maintaining the same dissolved oxygen level and a constant dilution rate,the biomass accumulation and RNA concentration in the RDMAB were 9.71% and 11.15% higher than those in the CCAB,respectively.Finally,the dilution rate of RDMAB was 16.7% higher than that of CCAB during con-tinuous fermentation while maintaining the same air aeration.In summary,RDMAB is more suitable for continuous fermentation processes.Developing new aeration and structural geometry in airlift bioreac-tors to enhance k_(L)a and gas holdup is becoming increasingly important to improve bioprocesses in a bioreactor.展开更多
In this work,a molecular-level kinetic model was built to simulate the vacuum residue(VR)coking process in a semi-batch laboratory-scale reaction kettle.A series of reaction rules for heavy oil coking were summarized ...In this work,a molecular-level kinetic model was built to simulate the vacuum residue(VR)coking process in a semi-batch laboratory-scale reaction kettle.A series of reaction rules for heavy oil coking were summarized and formulated based on the free radical reaction mechanism.Then,a large-scale molecularlevel reaction network was automatically generated by applying the reaction rules on the vacuum residue molecules.In order to accurately describe the physical change of each molecule in the reactor,we coupled the molecular-level kinetic model with a vapor–liquid phase separation model.The vapor–liquid phase separation model adopted the Peng-Robinson equation of state to calculate vapor–liquid equilibrium.A separation efficiency coefficient was introduced to represent the mass transfer during the phase separation.We used six sets of experimental data under various reaction conditions to regress the model parameters.The tuned model showed that there was an excellent agreement between the calculated values and experimental data.Moreover,we investigated the effect of reaction temperature and reaction time on the product yields.After a comprehensive evaluation of the reaction temperature and reaction time,the optimal reaction condition for the vacuum residue coking was also obtained.展开更多
Kinetic model of hypophosphite oxidation on a nickel electrode was studied in D2O solution in order to reach a better understanding of the oxidation mechanism. In the model the electrooxidation of hypophosphite underg...Kinetic model of hypophosphite oxidation on a nickel electrode was studied in D2O solution in order to reach a better understanding of the oxidation mechanism. In the model the electrooxidation of hypophosphite undergo a H abstraction of hypophosphite from the P-H bond to form the phosphorus-centered radical ·PHO2-, which subsequently is electrochemically reacted with water to form the final product, phosphite. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The process of hypophosphite electrooxidation could be well simulated by this model.展开更多
Kinetics of glycerol production by fermentation with osmotolerant yeast Candida krusei was studied. Suppositions of cell negative effect on and glucose inhibition in specific growth rate and glycerol assumption for en...Kinetics of glycerol production by fermentation with osmotolerant yeast Candida krusei was studied. Suppositions of cell negative effect on and glucose inhibition in specific growth rate and glycerol assumption for energy maintenance were made. Based on the suppositions, a set of unstructured kinetic models including cell groWth, glucose consumption and glycerol accumulation rate was proposed. To avoid the significant decrease of produced glyccerol in the latter fermentation stage, the fermentation was suggested to be ended when the concentration ratio of glycerol to glucose is close to 7.展开更多
A study on knowledge transfer in a mutli-agent organization is performed by applying the basic principle in physics such as the kinetic theory.Based on the theoretical analysis of the knowledge accumulation process an...A study on knowledge transfer in a mutli-agent organization is performed by applying the basic principle in physics such as the kinetic theory.Based on the theoretical analysis of the knowledge accumulation process and knowledge transfer attributes,a special type of knowledge field(KF)is introduced and the knowledge diffusion equation(KDE)is developed.The evolution of knowledge potential is modeled by lattice kinetic equation and verified by numerical experiments.The new equation-based modeling developed in this paper is meaningful to simulate and predict the knowledge transfer process in firms.The development of the lattice kinetic model(LKM)for knowledge transfer can contribute to the knowledge management theory,and the managers can also simulate the knowledge accumulation process by using the LKM.展开更多
To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wa...To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory.The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate.The foam film thickness,surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed.The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage,enhance the effect of Marangoni effect,and improve the stability of the foam liquid film.When the vibration frequency is close to the natural frequency of the foam liquid film,the vibration effect is the best,and the best vibration frequency is about 50 Hz.The higher the vibration acceleration,the faster the recovery rate of surfactant concentration in the foam liquid film is.The higher the vibration acceleration,the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is.It is not the higher the vibration acceleration,the better.The best vibration acceleration is about 0.5 times of gravity acceleration.Reasonable vibration parameters would greatly enhance the effect of Marangoni effect.The smaller the initial concentration of surfactant,the better the vibration works in enhancing Marangoni effect.展开更多
Fresh extruded rice-shaped kernels(FER) are remoulded rice products from cereals or seed flours, which have the advantages of safety, nutrition, health and time saving. However, the finished products are easy to react...Fresh extruded rice-shaped kernels(FER) are remoulded rice products from cereals or seed flours, which have the advantages of safety, nutrition, health and time saving. However, the finished products are easy to react with oxygen, so it is necessary to develop a fast, simple and reliable approach to monitor and predict the shelf-life of FER. A comprehensive mathematical model of FER shelf-life prediction was developed using a dynamic modelling approach based on real supply chain conditions. This predictive model was developed to determine four key indexes including acid value, iodine blue value, water uptake ratio and peroxide value. The results showed that when the peroxide value was 1.6849, the FER lost its edible value, nutritional value and commodity value. Moreover, the acid value and peroxide value of FER were used to establish a first-order kinetic model, and the iodine blue value of FER was suited for a zero-order kinetic model. The validation experiment of predicted and measured shelf life showed that the relative error was 3.12%, which was less than 5%. Therefore, this kinetic model could be used to predict the shelf-life of FER quickly and conveniently. The kinetic-based shelf-life prediction model proposed in this study is rapid and practical, providing theoretical basis and guidance for the establishment of quality monitoring and quality evaluation systems of FER during the production, storage, transport and marketing.展开更多
Coal gasification technology is a prominent technology in the coal chemical industry and serves as the fundamental basis for various process industries,including coal-based chemicals,coal-based liquid fuels,Integrated...Coal gasification technology is a prominent technology in the coal chemical industry and serves as the fundamental basis for various process industries,including coal-based chemicals,coal-based liquid fuels,Integrated Gasification Combined Cycle(IGCC) power generation,multi-generation systems,hydrogen production,and fuel cells.The gasification process generates significant quantities of ash residue,with annual emissions exceeding tens of millions of tons and accumulation reaching hundreds of millions of tons.Accordingly,there is an urgent need to investigate methods for its disposal.The combustion of gasified fine ash(GFA) was conducted in a tube furnace,and the conventional shrinking core model was modified to accurately predict the combustion behaviors at different temperatures(900℃-1500℃).We divided the reaction temperatures into three ranges,which is defined as unmelted combustion(TFT) and mixed combustion(DTFT),the surface ash of GFA grains fell off,and the residual carbon and gas-phase reactants were nearly no longer affected by the diffusion resistance,thus significantly accelerated the reaction of internal residual carbon.In order to predict the melt combustion process more accurately,the time term of the shrinkage core model(SCM) is modified,and the effective diffusion coefficient of T>FT is defined.展开更多
Liquid-phase transmission electron microscopy(LP-TEM)is a powerful tool to gain unique insights into dynamics at the nanoscale.The electron probe,however,can induce significant beam effects that often alter observed p...Liquid-phase transmission electron microscopy(LP-TEM)is a powerful tool to gain unique insights into dynamics at the nanoscale.The electron probe,however,can induce significant beam effects that often alter observed phenomena such as radiolysis of the aqueous phase.The magnitude of beam-induced radiolysis can be assessed by means of radiation chemistry simulations potentially enabling quantitative application of LP-TEM.Unfortunately,the computational cost of these simulations scales with the amount of reactants regarded.To minimize the computational cost,while maintaining accurate predictions,we optimize the parameter space for the solution chemistry of aqueous systems in general and for diluted HAuCl4 solutions in particular.Our results indicate that sparsened kinetic models can accurately describe steady-state formation during LP-TEM and provide a handy prerequisite for efficient multidimensional modeling.We emphasize that the demonstrated workflow can be easily generalized to any kinetic model involving multiple reaction pathways.展开更多
The best-fit equations of linear and non-linear forms of the two widely used kinetic models,namely pseudo-first-order and pseudo-second-order equations,were compared in this study.The experimental kinetics of methylen...The best-fit equations of linear and non-linear forms of the two widely used kinetic models,namely pseudo-first-order and pseudo-second-order equations,were compared in this study.The experimental kinetics of methylene blue adsorption on activated carbon was used for this research.Both the correlation coefficient(R2)and the normalized standard deviationΔq(%)were employed as error analysis methods to determine the best-fitting equations.The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data.The experimental kinetics may have been distorted by linearization of the linear kinetic equations,and thus,the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters.In addition,theΔq(%)method for error analysis may be better to determine the best-fitting model in this case.展开更多
Potato late blight,which is caused by Phytophthorainfestans(Mont.)de Bary,is a worldwide devastating disease for potato.It decreased yields of potato and caused unpredictable losses all over the world.Various simple s...Potato late blight,which is caused by Phytophthorainfestans(Mont.)de Bary,is a worldwide devastating disease for potato.It decreased yields of potato and caused unpredictable losses all over the world.Various simple statistical methods and forecasting models have been developed to predict and manage potato late blight.Meanwhile,there is a rising need to develop prediction models reflecting peroxidase(POD)activity,which is an important health index that varies with infection and correlated with stress resistance in plants.Thus,the aim of this research was to develop kinetic models to predict POD activity.Infection-induced changes in potato leaves stored in an artificial climate chest at 25°C were analyzed using hyperspectroscopy.Four prediction models were developed by using linear partial least squares(PLS)and nonlinear support vector machine(SVM)methods based on the full spectrum and effective wavelengths.The effective wavelengths were selected by the successive projection algorithm(SPA).In this study,the prediction model developed by means of SPA-SVM method obtained the best performance,with a Rp(correlation coefficient of prediction)value of 0.923 and a RMSEp(root mean square error of prediction)value of 24.326.Five-order kinetics models according to the prediction model were developed,and late blight disease can be predicted using this model.This study provided a theoretical basis for the prediction of latencies of late blight.展开更多
Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium C...Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium Cd chemical forms in two soil textural classes in Fars province-Iran at two soil water content(SWC)(flooded soil water content(FSWC)and field capacity soil water content(FCSWC))and study the kinetic modeling of Cd.Methods and materials:Variables were three levels of Cd(0,30 and 60 mg kg-1 of soil as CdSO4·8H2O),three levels of Zn(0,5 and 10 mg kg-1 of soil as Zn-EDTA)three level Incubation times(2,4 and eight weeks),two soil textural classes(clay and sandy clay loam)and two SWC.The randomized completed block design(RCBD)was used for this experiment.The Tessier sequential extraction method was used to determine the Cd concentration in(WsEx),(Fe-MnOx),(Car),(Om)and(Res)chemical forms.Results:In the FSWC,Zn reduced the Cd concentration in Fe-MnOx,Car and Om forms and increased the WsEx but had no significant effect on the Res form.Changes in the Cd chemical forms under the in-fluence of Zn in both soils followed a similar trend.In the FCSWC,Zn reduced the Cd concentration Car and Om forms and increased the Cd concentration in the Fe-MnOx and WsEx forms while had no sig-nificant effect on Res form in the sandy clay loam soil.In the clay soil adding Zn reduced the Cd con-centration in Car and Om fractions and increased the Fe-MnOx and Res forms while has no significant effect on WsEx form.The competitive transport and adsorption Interactions between these two ions caused the changing in the Cd concentration in its chemical forms.Zn reduces the Cd concentration in the forms which are easily released into the soil solution from where they can be absorbed by plants.The power function kinetic mode is the best fitted model which can describe the Cd adsorption in our soil samples.The clay and organic compounds control the Cd adsorption in soils.The higher rate of Cd adsorption in almost all shaking times shows that Cd has more ability to occupy the adsorption sites in soils.展开更多
Acidizing treatment in petroleum reservoirs is a short-term and viable strategy to preserve the productivity of a well.There is a major concern for the degradation of cement sheath integrity,leading to poor zonal isol...Acidizing treatment in petroleum reservoirs is a short-term and viable strategy to preserve the productivity of a well.There is a major concern for the degradation of cement sheath integrity,leading to poor zonal isolation and environmental issues.Therefore,it is essential to understand how the cement behaves when attacked by hydrochloric acid.In this study,a cement slurry by incorporation of the Henna extract,as an environmentally friendly cement additive,was synthesized as a potential solution to solve this problem.The characteristics of the treated cement slurry were compared with a reference slurry(w/c?0.44)which is composed of only cement and water.A kinetic study was carried out to evaluate the adsorption behavior of the cement slurries exposed to an acid solution with 0.1 M HCl in a range of 25 to 55C conditions.The features of the cement slurries were evaluated by multiple analytical techniques such as XRD,FTIR,TG,and DSC analysis.From the experimental data,it is concluded that the second-order Lagergren kinetic model revealed to be the best in describing kinetic isotherms taken,because the margin between experimental and calculated values was minor for this model.The results of the characterization and HCl interaction kinetic studies underlined the prominent protective role of Henna extract-modified cement slurry in the enhancement of the cement resistance against acid attack and utilization in environmentally favorable oil well acidizing treatments.展开更多
Based on the reported reaction networks,a novel six-component hydroisomerization reaction net-work with a new lumped species including C_(8)-naphthenes and C_(8)-paraffins is proposed and a kinetic model for a commerc...Based on the reported reaction networks,a novel six-component hydroisomerization reaction net-work with a new lumped species including C_(8)-naphthenes and C_(8)-paraffins is proposed and a kinetic model for a commercial unit is also developed.An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke forma-tion on the catalyst surface during the long-term opera-tion.The Runge-Kutta method is used to solve the ordinary differential equations of the model.The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential vari-able metric optimization method(BFGS).The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predic-tions and the plant observations.展开更多
Pulverized coal injection technique has been widely used as a means of reducing coke consumption during ironmaking process.Owing to the increasing shortage of fossil fuels,other substitutes such as biomass,plastic,and...Pulverized coal injection technique has been widely used as a means of reducing coke consumption during ironmaking process.Owing to the increasing shortage of fossil fuels,other substitutes such as biomass,plastic,and waste tires have been studied in recent years.Coke breeze as one of the by-products of coking industries has been investigated as a substitute for partial pulverized coals.The combustion characteristics of blended fuels were estimated based on the flammability index C and the combustion characteristic index S.For different coke breeze additions,the combustion was divided into two stages,and the apparent kinetic parameters of the two stages were estimated by fitting the experimental data to the shrinkage reaction model and shrinkage diffusion model,respectively.Results showed that with the increase in coke breeze addition from 15% to 60%,the indexes C and S decrease,and the activation energy of the first stage remains almost constant,while that of the last stage increases from 16.89 up to 67.18 kJ mol^(-1),which indicates that adding coke breeze decreases the combustion efficiency of pulverized coal.Comparing the combustion and kinetic parameters under different coke breeze addition conditions,the optimal addition amount is suggested to be within 15%.展开更多
文摘The pyrolysis of cyclohexane,methylcyclohexane,and ethylcyclohexane have been studied behind reflected shock waves at pressures of 5 and10 bar and at temperatures of 930-1550 K for 0.05%fuel diluted by Argon.A single-pulse shock tube(SPST)is used to perform the pyrolysis experiments at reaction times varying from 1.65 to 1.74 ms.Major products are obtained and quantified using gas chromatography analysis.A flame ionization detector and a thermal conductivity detector are used for species identification and quantification.Kinetic modeling has been performed using several detailed and lumped chemical kinetic mechanisms.Differences in modeling results among the kinetic models are described.Reaction path analysis and sensitivity analysis are performed to determine the important reactions controlling fuel pyrolysis and their influence on the predicted concentrations of reactant and product species profiles.The present work provides new fundamental knowledge in understating pyrolysis characteristics of cyclohexane compounds and additional data set for detailed kinetic mechanism development.
基金supported by the Open Project of Key Laboratory of Green Chemical Engineering Process of Ministry of Education[grant number GCP20190204]Hubei Key Laboratory of Novel Reactor and Green Chemistry Technology(Wuhan Institute of Technology)[grant number 40201005]+1 种基金Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education[grant number LKF201908]Graduate Innovative Fund of Wuhan Institute of Technology[grant number CX2021028].
文摘The ethylene aromatization is critical for the methanol to aromatics and light alkane dehydroaromatization process.The single-event microkinetic(SEMK)model combining the linear free energy theory and solid acid distribution concept were established and extend for the ethylene aromatization process,which can reduce the kinetic parameters and simplify the reaction network by comparison with the SEMK model including subtype elementary steps based on the type of carbenium ions.Further introducing deactivation parametersφinto the model and applying the linear free energy model to the deactivation experimental data,the obtained deactivation parametersφindicate that the carbon deposition precursors have the greatest impact on reducing the reaction rate of single-molecular reactions and the smallest impact on the hydrogen transfer reaction.Meanwhile,according to the change of reaction enthalpy,effect of carbenium ion structure on methylation,ethylation,cyclization and endo-βscission was investigated by introducing linear free energy concept into the SEMK model.The effect of different acid strengths on elementary steps was investigated based on the acid strength distribution model,it was found that the methylation and oligomerization reactions,the ali-βscission reaction,endo-βscission reaction and the cyclization reaction were more sensitive to strong acidity sites.The physisorption and chemisorption heat are separated from the protonation heat in the linear free energy kinetic model and the acid strength distribution kinetic model,and the absolute values of the obtained physisorption and chemisorption heat increase with the carbon number of carbenium ions.Furthermore,the parameters of the acid strength distribution kinetic model were applied to propane dehydroaromatization on H-ZSM-5 and the ethane dehydroaromatization on Zn/ZSM-5 to confirm the independence of parameters in the SEMK model with the similar reaction network.
文摘It is commonly accepted that, on social networks, the opinion of the agents with a higher connectivity, i.e., a larger number of followers, results in more convincing than that of the agents with a lower number of followers. By kinetic modeling approach, a kinetic model of opinion formation on social networks is derived, in which the distribution function depends on both the opinion and the connectivity of the agents. The opinion exchange process is governed by a Sznajd type model with three opinions, ±1, 0, and the social network is represented statistically with connectivity denoting the number of contacts of a given individual. The asymptotic mean opinion of a social network is determined in terms of the initial opinion and the connectivity of the agents.
基金financially supported by the SINOPEC Research and Develepment Project (No.120051-1)
文摘In order to investigate the hydrofining process of LCO for producing aromatics and gasoline,the selective hydrogenation of polycyclic aromatic hydrocarbons(PAHs),a major component of light cycle oil(LCO),was studied using a NiMoW/Al_(2)O_(3)catalyst.Based on the study of the reversible hydrogenation reaction,PAHs in the selective hydrogenation process could be effectively simulated by the modeled CH and CH_(2) groups,and the hydrodesulfurization and hydrodenitrogenation kinetic models could be further established in this process.The results showed that the kinetic models developed could fit the experimental data effectively and predict the content of S,N,and aromatics in the selective hydrogenation products of LCO.
基金supported by the National Natural Science Foundation of China(21621004,22078239)the Beijing-Tianjin-Hebei Basic Research Cooperation Project(B2021210008)+1 种基金Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(TSBICIP-KJGG-004)the Tianjin Development Program for Innovation and Entrepreneurship(2018)。
文摘Gamma-aminobutyric acid(GABA)is a natural non-protein functio nal amino acid,which has potential for fermentation industrial production by Lactobacillus brevis.This work investigated the batch fermentation process and developed a kinetic model based on substrate restrictive model established by experimental data from L25(5~6)orthogonal experiments.In this study,the OD600 value of fermentation broth was fixed to constant after reaching its maximum because the microorganism death showed no effect on the enzyme activity of glutamate decarboxylase(GAD).As pH is one of the key parameters in fermentation process,a pH-dependent kinetic model based on radial basis function was developed to enhance the practicality of the model.Furthermore,as to decrease the deviations between the simulated curves and the experimental data,the rolling correction strategy with OD600 values that was measured in real-time was introduced into this work to modify the model.Finally,the accu racy of the rolling corrected and pH-dependent model was validated by good fitness between the simulated curves and data of the initial batch fermentation(pH 5.2).As a result,this pH-dependent kinetic model revealed that the optimal pH for biomass growth is 5.6-5.7 and for GABA production is about 5,respectively.Therefore,the developed model is practical and convenient for the instruction of GABA fermentation production,and it has instructive significance for the industrial scale.
基金supported by National Key Research and Development Program of China (2020YFE0100100, 2021YFC21041002018YFA0901500)+1 种基金Basic Science (Natural Science) Research Project of Jiangsu Province Colleges and Universities(21KJB530014)Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture
文摘Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumetric oxygen mass transfer coefficient(k_(L)a)and gas holdup,as well as improve the bioprocess in a bioreactor.In this study,we compared mass transfer,gas holdup,and batch and con-tinuous fermentation for RNA production in CCAB and RDMAB.In addition,unstructured kinetic models for microbial growth,substrate utilization,and RNA formation were established.In batch fermentation,biomass,RNA yield,and substrate utilization in the RDMAB were higher than those in the CCAB,which indicates that dynamic membrane aeration produced a high k_(L)a by fine bubbles;a higher k_(L)a is more bene-ficial to aerobic fermentation.The starting time of continuous fermentation in the RDMAB was 20 h ear-lier than that in the CCAB,which greatly improved the biological process.During continuous fermentation,maintaining the same dissolved oxygen level and a constant dilution rate,the biomass accumulation and RNA concentration in the RDMAB were 9.71% and 11.15% higher than those in the CCAB,respectively.Finally,the dilution rate of RDMAB was 16.7% higher than that of CCAB during con-tinuous fermentation while maintaining the same air aeration.In summary,RDMAB is more suitable for continuous fermentation processes.Developing new aeration and structural geometry in airlift bioreac-tors to enhance k_(L)a and gas holdup is becoming increasingly important to improve bioprocesses in a bioreactor.
基金supported by the National Natural Science Foun-dation of China(22021004 and U19B2002).
文摘In this work,a molecular-level kinetic model was built to simulate the vacuum residue(VR)coking process in a semi-batch laboratory-scale reaction kettle.A series of reaction rules for heavy oil coking were summarized and formulated based on the free radical reaction mechanism.Then,a large-scale molecularlevel reaction network was automatically generated by applying the reaction rules on the vacuum residue molecules.In order to accurately describe the physical change of each molecule in the reactor,we coupled the molecular-level kinetic model with a vapor–liquid phase separation model.The vapor–liquid phase separation model adopted the Peng-Robinson equation of state to calculate vapor–liquid equilibrium.A separation efficiency coefficient was introduced to represent the mass transfer during the phase separation.We used six sets of experimental data under various reaction conditions to regress the model parameters.The tuned model showed that there was an excellent agreement between the calculated values and experimental data.Moreover,we investigated the effect of reaction temperature and reaction time on the product yields.After a comprehensive evaluation of the reaction temperature and reaction time,the optimal reaction condition for the vacuum residue coking was also obtained.
基金The work was supported by the Natural Science Foundation of the Education Commission of Hunan Province(No.99C57)
文摘Kinetic model of hypophosphite oxidation on a nickel electrode was studied in D2O solution in order to reach a better understanding of the oxidation mechanism. In the model the electrooxidation of hypophosphite undergo a H abstraction of hypophosphite from the P-H bond to form the phosphorus-centered radical ·PHO2-, which subsequently is electrochemically reacted with water to form the final product, phosphite. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The process of hypophosphite electrooxidation could be well simulated by this model.
基金From National Ninth Five Years Project (NO. 96-03-03-03A).
文摘Kinetics of glycerol production by fermentation with osmotolerant yeast Candida krusei was studied. Suppositions of cell negative effect on and glucose inhibition in specific growth rate and glycerol assumption for energy maintenance were made. Based on the suppositions, a set of unstructured kinetic models including cell groWth, glucose consumption and glycerol accumulation rate was proposed. To avoid the significant decrease of produced glyccerol in the latter fermentation stage, the fermentation was suggested to be ended when the concentration ratio of glycerol to glucose is close to 7.
基金supported by the National Natural Science Foundation of China(71472055 71871007)+2 种基金National Social Science Foundation of China(16AZD0006)Heilongjiang Philosophy and Social Science Research Project(19GLB087)the Fundamental Research Funds for the Central Universities(HIT.NSRIF.2019033)
文摘A study on knowledge transfer in a mutli-agent organization is performed by applying the basic principle in physics such as the kinetic theory.Based on the theoretical analysis of the knowledge accumulation process and knowledge transfer attributes,a special type of knowledge field(KF)is introduced and the knowledge diffusion equation(KDE)is developed.The evolution of knowledge potential is modeled by lattice kinetic equation and verified by numerical experiments.The new equation-based modeling developed in this paper is meaningful to simulate and predict the knowledge transfer process in firms.The development of the lattice kinetic model(LKM)for knowledge transfer can contribute to the knowledge management theory,and the managers can also simulate the knowledge accumulation process by using the LKM.
基金Supported by National Natural Science Foundation of China(51904320,51874339)The Special Fundamental Research Fund for the Central Universities(18CX02095A)。
文摘To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory.The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate.The foam film thickness,surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed.The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage,enhance the effect of Marangoni effect,and improve the stability of the foam liquid film.When the vibration frequency is close to the natural frequency of the foam liquid film,the vibration effect is the best,and the best vibration frequency is about 50 Hz.The higher the vibration acceleration,the faster the recovery rate of surfactant concentration in the foam liquid film is.The higher the vibration acceleration,the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is.It is not the higher the vibration acceleration,the better.The best vibration acceleration is about 0.5 times of gravity acceleration.Reasonable vibration parameters would greatly enhance the effect of Marangoni effect.The smaller the initial concentration of surfactant,the better the vibration works in enhancing Marangoni effect.
基金a grant from the National Key Research and Development Program of China(2017YFD0401305)the Key Research and Development Program of Shandong Province (2021CXGC010809)
文摘Fresh extruded rice-shaped kernels(FER) are remoulded rice products from cereals or seed flours, which have the advantages of safety, nutrition, health and time saving. However, the finished products are easy to react with oxygen, so it is necessary to develop a fast, simple and reliable approach to monitor and predict the shelf-life of FER. A comprehensive mathematical model of FER shelf-life prediction was developed using a dynamic modelling approach based on real supply chain conditions. This predictive model was developed to determine four key indexes including acid value, iodine blue value, water uptake ratio and peroxide value. The results showed that when the peroxide value was 1.6849, the FER lost its edible value, nutritional value and commodity value. Moreover, the acid value and peroxide value of FER were used to establish a first-order kinetic model, and the iodine blue value of FER was suited for a zero-order kinetic model. The validation experiment of predicted and measured shelf life showed that the relative error was 3.12%, which was less than 5%. Therefore, this kinetic model could be used to predict the shelf-life of FER quickly and conveniently. The kinetic-based shelf-life prediction model proposed in this study is rapid and practical, providing theoretical basis and guidance for the establishment of quality monitoring and quality evaluation systems of FER during the production, storage, transport and marketing.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA21040602)Youth Innovation Promotion Association,Chinese Academy of Sciences (Grant No.2020150)。
文摘Coal gasification technology is a prominent technology in the coal chemical industry and serves as the fundamental basis for various process industries,including coal-based chemicals,coal-based liquid fuels,Integrated Gasification Combined Cycle(IGCC) power generation,multi-generation systems,hydrogen production,and fuel cells.The gasification process generates significant quantities of ash residue,with annual emissions exceeding tens of millions of tons and accumulation reaching hundreds of millions of tons.Accordingly,there is an urgent need to investigate methods for its disposal.The combustion of gasified fine ash(GFA) was conducted in a tube furnace,and the conventional shrinking core model was modified to accurately predict the combustion behaviors at different temperatures(900℃-1500℃).We divided the reaction temperatures into three ranges,which is defined as unmelted combustion(TFT) and mixed combustion(DTFT),the surface ash of GFA grains fell off,and the residual carbon and gas-phase reactants were nearly no longer affected by the diffusion resistance,thus significantly accelerated the reaction of internal residual carbon.In order to predict the melt combustion process more accurately,the time term of the shrinkage core model(SCM) is modified,and the effective diffusion coefficient of T>FT is defined.
基金A.H.and B.F.acknowledge the financial support by the Federal Ministry of Education and Research(BMBF)of Germany in the programme H2Giga−StacIE(Project Identification Number:03HY103H).P.M.,J.H.,and K.J.J.M.acknowledge funding by the Deutsche Forschungsgemeinschaft(DFG,German Re-search Foundation)Project-ID 431791331SFB 1452.
文摘Liquid-phase transmission electron microscopy(LP-TEM)is a powerful tool to gain unique insights into dynamics at the nanoscale.The electron probe,however,can induce significant beam effects that often alter observed phenomena such as radiolysis of the aqueous phase.The magnitude of beam-induced radiolysis can be assessed by means of radiation chemistry simulations potentially enabling quantitative application of LP-TEM.Unfortunately,the computational cost of these simulations scales with the amount of reactants regarded.To minimize the computational cost,while maintaining accurate predictions,we optimize the parameter space for the solution chemistry of aqueous systems in general and for diluted HAuCl4 solutions in particular.Our results indicate that sparsened kinetic models can accurately describe steady-state formation during LP-TEM and provide a handy prerequisite for efficient multidimensional modeling.We emphasize that the demonstrated workflow can be easily generalized to any kinetic model involving multiple reaction pathways.
基金the Research Scheme of Education Department of Zhejiang Province,China(No.Y200806037).
文摘The best-fit equations of linear and non-linear forms of the two widely used kinetic models,namely pseudo-first-order and pseudo-second-order equations,were compared in this study.The experimental kinetics of methylene blue adsorption on activated carbon was used for this research.Both the correlation coefficient(R2)and the normalized standard deviationΔq(%)were employed as error analysis methods to determine the best-fitting equations.The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data.The experimental kinetics may have been distorted by linearization of the linear kinetic equations,and thus,the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters.In addition,theΔq(%)method for error analysis may be better to determine the best-fitting model in this case.
基金This research was supported by the Natural Science Foundation of China(31671965)the project of Key Laboratory of Agricultural Internet of Things,Ministry of Agriculture,China(2017001).
文摘Potato late blight,which is caused by Phytophthorainfestans(Mont.)de Bary,is a worldwide devastating disease for potato.It decreased yields of potato and caused unpredictable losses all over the world.Various simple statistical methods and forecasting models have been developed to predict and manage potato late blight.Meanwhile,there is a rising need to develop prediction models reflecting peroxidase(POD)activity,which is an important health index that varies with infection and correlated with stress resistance in plants.Thus,the aim of this research was to develop kinetic models to predict POD activity.Infection-induced changes in potato leaves stored in an artificial climate chest at 25°C were analyzed using hyperspectroscopy.Four prediction models were developed by using linear partial least squares(PLS)and nonlinear support vector machine(SVM)methods based on the full spectrum and effective wavelengths.The effective wavelengths were selected by the successive projection algorithm(SPA).In this study,the prediction model developed by means of SPA-SVM method obtained the best performance,with a Rp(correlation coefficient of prediction)value of 0.923 and a RMSEp(root mean square error of prediction)value of 24.326.Five-order kinetics models according to the prediction model were developed,and late blight disease can be predicted using this model.This study provided a theoretical basis for the prediction of latencies of late blight.
文摘Background and aims:Since few studies have existed in the literature about the effect of zinc(Zn)on cadmium(Cd)chemical forms in soils.Therefore,this study has been performed to determine the impact of Zn on cadmium Cd chemical forms in two soil textural classes in Fars province-Iran at two soil water content(SWC)(flooded soil water content(FSWC)and field capacity soil water content(FCSWC))and study the kinetic modeling of Cd.Methods and materials:Variables were three levels of Cd(0,30 and 60 mg kg-1 of soil as CdSO4·8H2O),three levels of Zn(0,5 and 10 mg kg-1 of soil as Zn-EDTA)three level Incubation times(2,4 and eight weeks),two soil textural classes(clay and sandy clay loam)and two SWC.The randomized completed block design(RCBD)was used for this experiment.The Tessier sequential extraction method was used to determine the Cd concentration in(WsEx),(Fe-MnOx),(Car),(Om)and(Res)chemical forms.Results:In the FSWC,Zn reduced the Cd concentration in Fe-MnOx,Car and Om forms and increased the WsEx but had no significant effect on the Res form.Changes in the Cd chemical forms under the in-fluence of Zn in both soils followed a similar trend.In the FCSWC,Zn reduced the Cd concentration Car and Om forms and increased the Cd concentration in the Fe-MnOx and WsEx forms while had no sig-nificant effect on Res form in the sandy clay loam soil.In the clay soil adding Zn reduced the Cd con-centration in Car and Om fractions and increased the Fe-MnOx and Res forms while has no significant effect on WsEx form.The competitive transport and adsorption Interactions between these two ions caused the changing in the Cd concentration in its chemical forms.Zn reduces the Cd concentration in the forms which are easily released into the soil solution from where they can be absorbed by plants.The power function kinetic mode is the best fitted model which can describe the Cd adsorption in our soil samples.The clay and organic compounds control the Cd adsorption in soils.The higher rate of Cd adsorption in almost all shaking times shows that Cd has more ability to occupy the adsorption sites in soils.
文摘Acidizing treatment in petroleum reservoirs is a short-term and viable strategy to preserve the productivity of a well.There is a major concern for the degradation of cement sheath integrity,leading to poor zonal isolation and environmental issues.Therefore,it is essential to understand how the cement behaves when attacked by hydrochloric acid.In this study,a cement slurry by incorporation of the Henna extract,as an environmentally friendly cement additive,was synthesized as a potential solution to solve this problem.The characteristics of the treated cement slurry were compared with a reference slurry(w/c?0.44)which is composed of only cement and water.A kinetic study was carried out to evaluate the adsorption behavior of the cement slurries exposed to an acid solution with 0.1 M HCl in a range of 25 to 55C conditions.The features of the cement slurries were evaluated by multiple analytical techniques such as XRD,FTIR,TG,and DSC analysis.From the experimental data,it is concluded that the second-order Lagergren kinetic model revealed to be the best in describing kinetic isotherms taken,because the margin between experimental and calculated values was minor for this model.The results of the characterization and HCl interaction kinetic studies underlined the prominent protective role of Henna extract-modified cement slurry in the enhancement of the cement resistance against acid attack and utilization in environmentally favorable oil well acidizing treatments.
基金This work was supportedby the NationalCreative Research Groups Science Foundation of China(No.60421002)Priority supported financially by the“New Century 151 Talent Project”of Zhejiang Province.
文摘Based on the reported reaction networks,a novel six-component hydroisomerization reaction net-work with a new lumped species including C_(8)-naphthenes and C_(8)-paraffins is proposed and a kinetic model for a commercial unit is also developed.An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke forma-tion on the catalyst surface during the long-term opera-tion.The Runge-Kutta method is used to solve the ordinary differential equations of the model.The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential vari-able metric optimization method(BFGS).The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predic-tions and the plant observations.
基金supports from the National Natural Science Foundation of China(Nos.51604148,51874171,and 51974154).
文摘Pulverized coal injection technique has been widely used as a means of reducing coke consumption during ironmaking process.Owing to the increasing shortage of fossil fuels,other substitutes such as biomass,plastic,and waste tires have been studied in recent years.Coke breeze as one of the by-products of coking industries has been investigated as a substitute for partial pulverized coals.The combustion characteristics of blended fuels were estimated based on the flammability index C and the combustion characteristic index S.For different coke breeze additions,the combustion was divided into two stages,and the apparent kinetic parameters of the two stages were estimated by fitting the experimental data to the shrinkage reaction model and shrinkage diffusion model,respectively.Results showed that with the increase in coke breeze addition from 15% to 60%,the indexes C and S decrease,and the activation energy of the first stage remains almost constant,while that of the last stage increases from 16.89 up to 67.18 kJ mol^(-1),which indicates that adding coke breeze decreases the combustion efficiency of pulverized coal.Comparing the combustion and kinetic parameters under different coke breeze addition conditions,the optimal addition amount is suggested to be within 15%.
