The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availabi...The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availability and is constrained by air temperature,it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms.Here,a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point(a measure of humidity)on local temperature evolving with escalating global mean surface temperature.By applying these models to 297 weather stations in seven regions in China,the study analyzes historical trends of humid-heat and dry-hot days,and projects their changes under global warming of 2.0℃ and 4.5℃.In response to global warming,rising trends of humid-heat extremes,while weakening trends of dry-hot extremes,are observed at most stations in Northeast China.Additionally,results indicate an increasing trend in dry-hot extremes at numerous stations across central China,but a rise in humid-heat extremes over Northwest China and coastal regions.These trends found in the current climate state are projected to intensify under 2.0℃ and 4.5℃ warming,possibly influenced by the heterogeneous variations in precipitation,soil moisture,and water vapor fluxes.Requiring much lower computational resources than coupled climate models,these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming,potentially informing the risk management of compound humid-heat extremes on a local scale.展开更多
Aim To study the distribution pattern, antineoplastic activity and immunocompetence of a novel organoselenium compound Eb and investigate its in vivo antineoplastic potential. Methods Eb was administered to Kunming ...Aim To study the distribution pattern, antineoplastic activity and immunocompetence of a novel organoselenium compound Eb and investigate its in vivo antineoplastic potential. Methods Eb was administered to Kunming mice (dosage, 0.1 g·kg^(-1)·d^(-1)) intragastrically for 7 successive days. The contents of selenium in heart, liver, spleen, kidneys, lungs, stomach, brain, muscle, and bone were determined by fluorometric method on the eighth day. MTT assay was used to study tumor growth inhibition of Eb in vitro, and lymphocyte transformation, hemolysin formation and phagocytosis assay were used to study its immunocompetence. Results After 7 days′ administration of Eb, the tissue contents of sele-(nium) in liver, spleen, lungs, kidneys, and bone of mice increased, especially those in liver and spleen increased significan-tly, compared with controls; but no significant changes of such contents were found in muscle, heart, brain, and stomach. Eb demonstrated inhibitory effects on human Bel-7402, BGC-823, and Calu-3 cancer cell lines in vitro. Eb also showed ability to enhance lymphocyte transformation and serum hemolysin formation in vitro and increase the phagocytosis of macrophages. Conclusion The validated antitumor and immunostimulatory activities of Eb suggest a hypothesis that Eb may behave as a biological response modifier when used as an antitumor agent. Eb is worthy of further study in developing a new antineoplastic and immunity enhancing agent in the light of its antitumor activity, immunocompetence and specific distribution in liver, lungs, kidneys, bone, and spleen.展开更多
A novel organoselenium compound,WB（1,2-[bis（1,2-benzisoselenazolone-3（2H）-ketone）]pentane） has indicated anti-tumor activity.Its pharmacokinetic data has never been determined.By using the H22 tumor bearing mous...A novel organoselenium compound,WB（1,2-[bis（1,2-benzisoselenazolone-3（2H）-ketone）]pentane） has indicated anti-tumor activity.Its pharmacokinetic data has never been determined.By using the H22 tumor bearing mouse model,the tissue distribution of WB after single and four consecutive doses（both were 120 mg/kg/d） was explored.The selenium content of the tissues was used as an indicator of WB absorption,distribution and metabolism.The selenium in the heart,liver, spleen,kidneys,lungs,stomach,pancreas,brain,colon,intestine,testes,plasma,and tumor were determined by generation atomic fluorescence spectrometry（AFS）.With single or multiple oral administration of WB,the selenium content significantly increased in the liver,stomach,colon,and intestine.The selenium content in the spleen,lungs,pancreas,testes,plasma and tumor also increased compared with the controls;but no significant changes were found in the brain and kidney.WB and its metabolites distributed predominantly in the colon,liver,stomach and intestine,which resulted in a significant increase in the selenium content in both groups.There was no observed significant accumulation of WB in the vital organs.展开更多
A new compound distribution model for extreme wave heights of typhoon-affected sea areas is proposed on the basis of the maximum-entropy principle. The new model is formed by nesting a discrete distribution in a conti...A new compound distribution model for extreme wave heights of typhoon-affected sea areas is proposed on the basis of the maximum-entropy principle. The new model is formed by nesting a discrete distribution in a continuous one, having eight parameters which can be determined in terms of observed data of typhoon occurrence-frequency and extreme wave heights by numerically solving two sets of equations derived in this paper. The model is examined by using it to predict the N-year return-period wave height at two hydrology stations in the Yellow Sea, and the predicted results are compared with those predicted by use of some other compound distribution models. Examinations and comparisons show that the model has some advantages for predicting the N-year return-period wave height in typhoon-affected sea areas.展开更多
This article considers estimation of the unknown parameters for the compound Rayleigh distribution (CRD) based on a new life test plan called a progressive first failure-censored plan introduced by Wu and Kus (2009). ...This article considers estimation of the unknown parameters for the compound Rayleigh distribution (CRD) based on a new life test plan called a progressive first failure-censored plan introduced by Wu and Kus (2009). We consider the maximum likelihood and Bayesian inference of the unknown parameters of the model, as well as the reliability and hazard rate functions. This was done using the conjugate prior for the shape parameter, and discrete prior for the scale parameter. The Bayes estimators hav been obtained relative to both symmetric (squared error) and asymmetric (LINEX and general entropy (GE)) loss functions. It has been seen that the symmetric and asymmetric Bayes estimators are obtained in closed forms. Also, based on this new censoring scheme, approximate confidence intervals for the parameters of CRD are developed. A practical example using real data set was used for illustration. Finally, to assess the performance of the proposed estimators, some numerical results using Monte Carlo simulation study were reported.展开更多
This paper puts forward a Poisson-generalized Pareto (Poisson-GP) distribution. This new form of compound extreme value distribution expands the existing application of compound extreme value distribution, and can be ...This paper puts forward a Poisson-generalized Pareto (Poisson-GP) distribution. This new form of compound extreme value distribution expands the existing application of compound extreme value distribution, and can be applied to predicting financial risk, large insurance settlement and high-grade earthquake, etc. Compared with the maximum likelihood estimation (MLE) and compound moment estimation (CME), probability-weighted moment estimation (PWME) is used to estimate the parameters of the distribution function. The specific formulas are presented. Through Monte Carlo simulation with sample sizes 10, 20, 50, 100, 1 000, it is concluded that PWME is an efficient method and it behaves steadily. The mean square errors (MSE) of estimators by PWME are much smaller than those of estimators by CME, and there is no significant difference between PWME and MLE. Finally, an example of foreign exchange rate is given. For Dollar/Pound exchange rates from 1990-01-02 to 2006-12-29, this paper formulates the distribution function of the largest loss among the investment losses exceeding a certain threshold by Poisson-GP compound extreme value distribution, and obtains predictive values at different confidence levels.展开更多
With the development of automation in smart grids,network reconfiguration is becoming a feasible approach for improving the operation of distribution systems.A novel reconfiguration strategy was presented to get the o...With the development of automation in smart grids,network reconfiguration is becoming a feasible approach for improving the operation of distribution systems.A novel reconfiguration strategy was presented to get the optimal configuration of improving economy of the system,and then identifying the important nodes.In this strategy,the objectives increase the node importance degree and decrease the active power loss subjected to operational constraints.A compound objective function with weight coefficients is formulated to balance the conflict of the objectives.Then a novel quantum particle swarm optimization based on loop switches hierarchical encoded was employed to address the compound objective reconfiguration problem.Its main contribution is the presentation of the hierarchical encoded scheme which is used to generate the population swarm particles of representing only radial connected solutions.Because the candidate solutions are feasible,the search efficiency would improve dramatically during the optimization process without tedious topology verification.To validate the proposed strategy,simulations are carried out on the test systems.The results are compared with other techniques in order to evaluate the performance of the proposed method.展开更多
In this paper, we study the compound binomial model in Markovian environment, which is proposed by Cossette, et al. （2003）. We obtain the recursive formula of the joint distributions of T, X（T - 1） and ｜X（T）｜...In this paper, we study the compound binomial model in Markovian environment, which is proposed by Cossette, et al. （2003）. We obtain the recursive formula of the joint distributions of T, X（T - 1） and ｜X（T）｜（i.e., the time of ruin, the surplus before ruin and the deficit at ruin） by the method of mass function of up-crossing zero points, as given by Liu and Zhao （2007）. By using the same method, the recursive formula of supremum distribution is obtained. An example is included to illustrate the results of the model.展开更多
The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while ...The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while M(1) and M(2) sites were shared by trivalent and tetravalent cations, the relative content of tetravalent at M(1) sites was higher than at M(2) sites. During substitution process, the trivalent cations preferred to occupy M(3) sites, tetravalent ones preferred to occupy M(2) sites. The occupancy of trivalent and tetravalent cations at M sites would change with the substitution展开更多
The droplet size distribution with large-holed compound sieve tray operating in the spray regime is measured by using a double electrical probes technique in a cold model column of 400 mm diameter. The results indicat...The droplet size distribution with large-holed compound sieve tray operating in the spray regime is measured by using a double electrical probes technique in a cold model column of 400 mm diameter. The results indicate that the hole F-factor F0 and surface tension are the main factors which influence the liquid dispersion expressed by the Sauter mean diameter D32. A correlation of D32 on surface tension, viscosity, .F-factor, weir height and liquid flow rate is proposed.展开更多
The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged ...The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.展开更多
Industrial coking facilities are an important emission source for volatile organic compounds(VOCs).This study analyzed the atmospheric VOC characteristics within an industrial coking facility and its surrounding envir...Industrial coking facilities are an important emission source for volatile organic compounds(VOCs).This study analyzed the atmospheric VOC characteristics within an industrial coking facility and its surrounding environment.Average concentrations of total VOCs(TVOCs)in the surrounding residential activity areas(R1 and R2),the coking facility(CF)and the control area(CA)were determined to be 138.5,47.8,550.0,and 15.0μg/m^(3),respectively.The cold drum process and coking and quenching areas within the coking facility were identified as the main polluting processes.The spatial variation in VOCs composition was analyzed,showing that VOCs in the coking facility and surrounding areas were mainly dominated by aromatic compounds such as BTX(benzene,toluene,and xylenes)and naphthalene,with concentrations being negatively correlated with the distance from the coking facility(p<0.01).The sources of VOCs in different functional areas across the monitoring area were analyzed,finding that coking emissions accounted for 73.5%,33.3% and 27.7% of TVOCs in CF,R1 and R2,respectively.These results demonstrated that coking emissions had a significant impact on VOC concentrations in the areas surrounding coking facility.This study evaluates the spatial variation in exposure to VOCs,providing important information for the influence of VOCs concentration posed by coking facility to surrounding residents and the development of strategies for VOC abatement.展开更多
We have investigated the distributions of alkylcarbazoles in a series of crude oils with different biodegradation extents, in combination with biomarker parameters, stable carbon isotopic ratios and viscosities. The a...We have investigated the distributions of alkylcarbazoles in a series of crude oils with different biodegradation extents, in combination with biomarker parameters, stable carbon isotopic ratios and viscosities. The analyses showed that slight biodegradation has little effect on alkylcarbazoles. The concentrations of C\-0-, C\-1-, and C\-2-carbazoles seem to display a slight decrease with biodegradation through the moderately biodegraded stage, and an abrupt decrease to the heavily biodegraded stage. The relative concentrations of C\-0-, C\-1-, and C\-2-carbazoles do not show any apparent change in the non-heavily biodegraded stages, but through non-heavily biodegraded to heavily biodegraded stages, the percentages of C\-0- and C\-1-carbazoles decrease, and those of C\-2-carbazoles increase significantly, which may indicate that C\-2-carbazoles are more resistant to biodegradation than lower homologous species. As to C\-2-carbazole isomers, the relative concentrations of the pyrrolic N-H-shielded, pyrrolic N-H partially shielded and pyrrolic N-H-exposed isomers do not show any obvious variation in the non-heavily biodegraded oil, but there is an abrupt change through the mid-biodegraded stage to the heavily biodegraded stage.展开更多
The elemental distribution and microstructure near the surface of high-Mn/Al austenitic low-density steel were investigated after isothermal holding at temperatures of 900-1200℃ in different atmospheres,including air...The elemental distribution and microstructure near the surface of high-Mn/Al austenitic low-density steel were investigated after isothermal holding at temperatures of 900-1200℃ in different atmospheres,including air,N_(2),and N_(2)+CO_(2).No ferrite was formed near the surface of the experimental steel during isothermal holding at 900 and 1000℃ in air,while ferrite was formed near the steel sur-face at holding temperatures of 1100 and 1200℃.The ferrite fraction was larger at 1200℃ because more C and Mn diffused to the sur-face,exuded from the steel,and then reacted with N and O to form oxidation products.The thickness of the compound scale increased owing to the higher diffusion rate at higher temperatures.In addition,after isothermal holding at 1100℃ in N_(2),the Al content near the surface slightly decreased,while the C and Mn contents did not change.Therefore,no ferrite was formed near the surface.However,the near-surface C and Al contents decreased after holding at 1100℃in the N_(2)+CO_(2)mixed atmosphere,resulting in the formation of a small amount of ferrite.The compound scale was thickest in N_(2),followed by the N_(2)+CO_(2)mixed atmosphere,and thinnest in air.Overall,the element loss and ferrite fraction were largest after holding in air at the same temperature.The differences in element loss and ferrite frac-tion between in N_(2) and N_(2)+CO_(2)atmospheres were small,but the compound scale formed in N_(2) was significantly thicker.According to these results,N_(2)+CO_(2)is the ideal heating atmosphere for the industrial production of high-Mn/Al austenitic low-density steel.展开更多
基金supported by the National Natural Science Foundation of China[grant number 42175066]the Shanghai International Science and Technology Partnership Project[grant number 21230780200].
文摘The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availability and is constrained by air temperature,it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms.Here,a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point(a measure of humidity)on local temperature evolving with escalating global mean surface temperature.By applying these models to 297 weather stations in seven regions in China,the study analyzes historical trends of humid-heat and dry-hot days,and projects their changes under global warming of 2.0℃ and 4.5℃.In response to global warming,rising trends of humid-heat extremes,while weakening trends of dry-hot extremes,are observed at most stations in Northeast China.Additionally,results indicate an increasing trend in dry-hot extremes at numerous stations across central China,but a rise in humid-heat extremes over Northwest China and coastal regions.These trends found in the current climate state are projected to intensify under 2.0℃ and 4.5℃ warming,possibly influenced by the heterogeneous variations in precipitation,soil moisture,and water vapor fluxes.Requiring much lower computational resources than coupled climate models,these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming,potentially informing the risk management of compound humid-heat extremes on a local scale.
文摘Aim To study the distribution pattern, antineoplastic activity and immunocompetence of a novel organoselenium compound Eb and investigate its in vivo antineoplastic potential. Methods Eb was administered to Kunming mice (dosage, 0.1 g·kg^(-1)·d^(-1)) intragastrically for 7 successive days. The contents of selenium in heart, liver, spleen, kidneys, lungs, stomach, brain, muscle, and bone were determined by fluorometric method on the eighth day. MTT assay was used to study tumor growth inhibition of Eb in vitro, and lymphocyte transformation, hemolysin formation and phagocytosis assay were used to study its immunocompetence. Results After 7 days′ administration of Eb, the tissue contents of sele-(nium) in liver, spleen, lungs, kidneys, and bone of mice increased, especially those in liver and spleen increased significan-tly, compared with controls; but no significant changes of such contents were found in muscle, heart, brain, and stomach. Eb demonstrated inhibitory effects on human Bel-7402, BGC-823, and Calu-3 cancer cell lines in vitro. Eb also showed ability to enhance lymphocyte transformation and serum hemolysin formation in vitro and increase the phagocytosis of macrophages. Conclusion The validated antitumor and immunostimulatory activities of Eb suggest a hypothesis that Eb may behave as a biological response modifier when used as an antitumor agent. Eb is worthy of further study in developing a new antineoplastic and immunity enhancing agent in the light of its antitumor activity, immunocompetence and specific distribution in liver, lungs, kidneys, bone, and spleen.
基金National Major Projects on Drug Research and Technology(Grant No.2009ZX09103-032)
文摘A novel organoselenium compound,WB（1,2-[bis（1,2-benzisoselenazolone-3（2H）-ketone）]pentane） has indicated anti-tumor activity.Its pharmacokinetic data has never been determined.By using the H22 tumor bearing mouse model,the tissue distribution of WB after single and four consecutive doses（both were 120 mg/kg/d） was explored.The selenium content of the tissues was used as an indicator of WB absorption,distribution and metabolism.The selenium in the heart,liver, spleen,kidneys,lungs,stomach,pancreas,brain,colon,intestine,testes,plasma,and tumor were determined by generation atomic fluorescence spectrometry（AFS）.With single or multiple oral administration of WB,the selenium content significantly increased in the liver,stomach,colon,and intestine.The selenium content in the spleen,lungs,pancreas,testes,plasma and tumor also increased compared with the controls;but no significant changes were found in the brain and kidney.WB and its metabolites distributed predominantly in the colon,liver,stomach and intestine,which resulted in a significant increase in the selenium content in both groups.There was no observed significant accumulation of WB in the vital organs.
基金supported by the Open Fund of the Key Laboratory of Research on Marine Hazards Forecasting (Grant No.LOMF1101)the Shanghai Typhoon Research Fund (Grant No. 2009ST05)the National Natural Science Foundation of China(Grant No. 40776006)
文摘A new compound distribution model for extreme wave heights of typhoon-affected sea areas is proposed on the basis of the maximum-entropy principle. The new model is formed by nesting a discrete distribution in a continuous one, having eight parameters which can be determined in terms of observed data of typhoon occurrence-frequency and extreme wave heights by numerically solving two sets of equations derived in this paper. The model is examined by using it to predict the N-year return-period wave height at two hydrology stations in the Yellow Sea, and the predicted results are compared with those predicted by use of some other compound distribution models. Examinations and comparisons show that the model has some advantages for predicting the N-year return-period wave height in typhoon-affected sea areas.
文摘This article considers estimation of the unknown parameters for the compound Rayleigh distribution (CRD) based on a new life test plan called a progressive first failure-censored plan introduced by Wu and Kus (2009). We consider the maximum likelihood and Bayesian inference of the unknown parameters of the model, as well as the reliability and hazard rate functions. This was done using the conjugate prior for the shape parameter, and discrete prior for the scale parameter. The Bayes estimators hav been obtained relative to both symmetric (squared error) and asymmetric (LINEX and general entropy (GE)) loss functions. It has been seen that the symmetric and asymmetric Bayes estimators are obtained in closed forms. Also, based on this new censoring scheme, approximate confidence intervals for the parameters of CRD are developed. A practical example using real data set was used for illustration. Finally, to assess the performance of the proposed estimators, some numerical results using Monte Carlo simulation study were reported.
基金National Natural Science Foundation of China (No.70573077)
文摘This paper puts forward a Poisson-generalized Pareto (Poisson-GP) distribution. This new form of compound extreme value distribution expands the existing application of compound extreme value distribution, and can be applied to predicting financial risk, large insurance settlement and high-grade earthquake, etc. Compared with the maximum likelihood estimation (MLE) and compound moment estimation (CME), probability-weighted moment estimation (PWME) is used to estimate the parameters of the distribution function. The specific formulas are presented. Through Monte Carlo simulation with sample sizes 10, 20, 50, 100, 1 000, it is concluded that PWME is an efficient method and it behaves steadily. The mean square errors (MSE) of estimators by PWME are much smaller than those of estimators by CME, and there is no significant difference between PWME and MLE. Finally, an example of foreign exchange rate is given. For Dollar/Pound exchange rates from 1990-01-02 to 2006-12-29, this paper formulates the distribution function of the largest loss among the investment losses exceeding a certain threshold by Poisson-GP compound extreme value distribution, and obtains predictive values at different confidence levels.
基金Project(61102039)supported by the National Natural Science Foundation of ChinaProject(2014AA052600)supported by National Hi-tech Research and Development Plan,China
文摘With the development of automation in smart grids,network reconfiguration is becoming a feasible approach for improving the operation of distribution systems.A novel reconfiguration strategy was presented to get the optimal configuration of improving economy of the system,and then identifying the important nodes.In this strategy,the objectives increase the node importance degree and decrease the active power loss subjected to operational constraints.A compound objective function with weight coefficients is formulated to balance the conflict of the objectives.Then a novel quantum particle swarm optimization based on loop switches hierarchical encoded was employed to address the compound objective reconfiguration problem.Its main contribution is the presentation of the hierarchical encoded scheme which is used to generate the population swarm particles of representing only radial connected solutions.Because the candidate solutions are feasible,the search efficiency would improve dramatically during the optimization process without tedious topology verification.To validate the proposed strategy,simulations are carried out on the test systems.The results are compared with other techniques in order to evaluate the performance of the proposed method.
基金Supported by the National Natural Science Foundation of China (10671176, 10771192, 70871103)
文摘In this paper, we study the compound binomial model in Markovian environment, which is proposed by Cossette, et al. （2003）. We obtain the recursive formula of the joint distributions of T, X（T - 1） and ｜X（T）｜（i.e., the time of ruin, the surplus before ruin and the deficit at ruin） by the method of mass function of up-crossing zero points, as given by Liu and Zhao （2007）. By using the same method, the recursive formula of supremum distribution is obtained. An example is included to illustrate the results of the model.
文摘The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while M(1) and M(2) sites were shared by trivalent and tetravalent cations, the relative content of tetravalent at M(1) sites was higher than at M(2) sites. During substitution process, the trivalent cations preferred to occupy M(3) sites, tetravalent ones preferred to occupy M(2) sites. The occupancy of trivalent and tetravalent cations at M sites would change with the substitution
基金Supported by the Key Technologies R&D Programme (No. 95-530-01-02).
文摘The droplet size distribution with large-holed compound sieve tray operating in the spray regime is measured by using a double electrical probes technique in a cold model column of 400 mm diameter. The results indicate that the hole F-factor F0 and surface tension are the main factors which influence the liquid dispersion expressed by the Sauter mean diameter D32. A correlation of D32 on surface tension, viscosity, .F-factor, weir height and liquid flow rate is proposed.
基金Under the auspices of National Basic Research Program of China(No.2011CB403303)National Key Research and Development Program of China(No.2016YFC0402408-5)National Natural Science Foundation of China(No.51179181,40788001)
文摘The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.
基金supported by the National Key R&D Program of China(Nos.2019YFC1804502 and 2019YFC1804503)the Guangdong Provincial Natural Science Fund for Distinguished Young Scholars(No.2022B1515020051)+2 种基金the National Natural Science Foundation of China(No.42077332)the Science and Technology Program of Guangzhou(No.202201010149)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Z032)。
文摘Industrial coking facilities are an important emission source for volatile organic compounds(VOCs).This study analyzed the atmospheric VOC characteristics within an industrial coking facility and its surrounding environment.Average concentrations of total VOCs(TVOCs)in the surrounding residential activity areas(R1 and R2),the coking facility(CF)and the control area(CA)were determined to be 138.5,47.8,550.0,and 15.0μg/m^(3),respectively.The cold drum process and coking and quenching areas within the coking facility were identified as the main polluting processes.The spatial variation in VOCs composition was analyzed,showing that VOCs in the coking facility and surrounding areas were mainly dominated by aromatic compounds such as BTX(benzene,toluene,and xylenes)and naphthalene,with concentrations being negatively correlated with the distance from the coking facility(p<0.01).The sources of VOCs in different functional areas across the monitoring area were analyzed,finding that coking emissions accounted for 73.5%,33.3% and 27.7% of TVOCs in CF,R1 and R2,respectively.These results demonstrated that coking emissions had a significant impact on VOC concentrations in the areas surrounding coking facility.This study evaluates the spatial variation in exposure to VOCs,providing important information for the influence of VOCs concentration posed by coking facility to surrounding residents and the development of strategies for VOC abatement.
基金ThisprojectwasfinanciallysupportedbytheYouthKnowledge InnovationFoundationofCNPC (No .0 0Z130 4)
文摘We have investigated the distributions of alkylcarbazoles in a series of crude oils with different biodegradation extents, in combination with biomarker parameters, stable carbon isotopic ratios and viscosities. The analyses showed that slight biodegradation has little effect on alkylcarbazoles. The concentrations of C\-0-, C\-1-, and C\-2-carbazoles seem to display a slight decrease with biodegradation through the moderately biodegraded stage, and an abrupt decrease to the heavily biodegraded stage. The relative concentrations of C\-0-, C\-1-, and C\-2-carbazoles do not show any apparent change in the non-heavily biodegraded stages, but through non-heavily biodegraded to heavily biodegraded stages, the percentages of C\-0- and C\-1-carbazoles decrease, and those of C\-2-carbazoles increase significantly, which may indicate that C\-2-carbazoles are more resistant to biodegradation than lower homologous species. As to C\-2-carbazole isomers, the relative concentrations of the pyrrolic N-H-shielded, pyrrolic N-H partially shielded and pyrrolic N-H-exposed isomers do not show any obvious variation in the non-heavily biodegraded oil, but there is an abrupt change through the mid-biodegraded stage to the heavily biodegraded stage.
基金gratefully acknowledge the financial support from the National Natural Science Foundation of China(No.U20A20270)China Postdoctoral Science Foundation(No.2022M722486).We would like to thank Dr.Wei Yuan at the Analytical&Testing Center of Wuhan University of Science and Technology for the help on EPMA analyses.
文摘The elemental distribution and microstructure near the surface of high-Mn/Al austenitic low-density steel were investigated after isothermal holding at temperatures of 900-1200℃ in different atmospheres,including air,N_(2),and N_(2)+CO_(2).No ferrite was formed near the surface of the experimental steel during isothermal holding at 900 and 1000℃ in air,while ferrite was formed near the steel sur-face at holding temperatures of 1100 and 1200℃.The ferrite fraction was larger at 1200℃ because more C and Mn diffused to the sur-face,exuded from the steel,and then reacted with N and O to form oxidation products.The thickness of the compound scale increased owing to the higher diffusion rate at higher temperatures.In addition,after isothermal holding at 1100℃ in N_(2),the Al content near the surface slightly decreased,while the C and Mn contents did not change.Therefore,no ferrite was formed near the surface.However,the near-surface C and Al contents decreased after holding at 1100℃in the N_(2)+CO_(2)mixed atmosphere,resulting in the formation of a small amount of ferrite.The compound scale was thickest in N_(2),followed by the N_(2)+CO_(2)mixed atmosphere,and thinnest in air.Overall,the element loss and ferrite fraction were largest after holding in air at the same temperature.The differences in element loss and ferrite frac-tion between in N_(2) and N_(2)+CO_(2)atmospheres were small,but the compound scale formed in N_(2) was significantly thicker.According to these results,N_(2)+CO_(2)is the ideal heating atmosphere for the industrial production of high-Mn/Al austenitic low-density steel.
