In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(...In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(UrQMD) model with GEMINI++ code. The UrQMD model was adopted to simulate the dynamic evolution of heavy-ion collisions, whereas the GEMINI++ code was used to simulate the decay of primary fragments produced by UrQMD. The calculated results were compared with the INDRA and FOPI experimental data. It was found that the rapidity distribution, collective flows, and nuclear stopping power were affected to a certain extent by the decay of primary fragments, especially at lower beam energies. Furthermore, the experimental data of the collective flows and nuclear stopping power at the investigated beam energies were better reproduced when the sequential decay effect was included.展开更多
The present paper contains the reaction mechanism of the rare earth complex with 2-(2-arsenophenylazo)-7-(2, 6-dichloro-4-fluoro-phenylazo)- 1, 8-dihydroxynaphthalene-3, 6-disulfonic acid (DCF-arsenazo) studied prelim...The present paper contains the reaction mechanism of the rare earth complex with 2-(2-arsenophenylazo)-7-(2, 6-dichloro-4-fluoro-phenylazo)- 1, 8-dihydroxynaphthalene-3, 6-disulfonic acid (DCF-arsenazo) studied preliminarily with a fully automated stopped-flow analyzer. A method with a high sensitivity and selectivity is proposed for the simultaneous determination of samarium and gadolinium based on the differential kinetic reaction of the rare earth complex with DCF-arsenazo. Sm and Gd in their concentrated oxides were determined with the relative errors less than 6%.展开更多
A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The ...A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.展开更多
A highly sensitive stopped-flow spectrophotometry kinetic method was proposed for quantification phenoxyl radicals based on their accelerating effect on the oxidation of nicotinamide adenine dinucleotide （NADH）. Phe...A highly sensitive stopped-flow spectrophotometry kinetic method was proposed for quantification phenoxyl radicals based on their accelerating effect on the oxidation of nicotinamide adenine dinucleotide （NADH）. Phenoxyl radicals generated from as low as 1×10^-8 mol/L 2,4-DCP can be readily detected with the proposed method and the detecting limit was 2.5×10^-9 mol/L.展开更多
To determine how bus stop design influences mixed traffic operation near Chinese bus stops,a new theoretical method was developed by using additive-conflict-flows procedure.The procedure was extended from homogeneous ...To determine how bus stop design influences mixed traffic operation near Chinese bus stops,a new theoretical method was developed by using additive-conflict-flows procedure.The procedure was extended from homogeneous traffic flow to mixed traffic flow.Based on the procedure and queuing theory,car capacity and speed models were proposed for three types of bus stops including curbside,bus bay and bicycle detour.The effects of various combinations of bus stop type,traffic volume,bus dwell time,and berth number on traffic operations were investigated.The results indicate that traffic volume,bus dwell time and berth number have negative effects on traffic operations for any type of bus stops.For different types of bus stops,at car volumes above approximately 200 vehicles per hour,the bus bay and bicycle detour designs provide more benefits than the curbside design.As traffic volume increases,the benefit firstly increases in uncongested conditions and then decreases in congested conditions.It reaches the maximum at car volumes nearly 1 100 vehicles per hour.The results can be used to aid in the selection of a preferred bus stop design for a given traffic volume in developing countries.展开更多
The effects of the in-medium nucleon-nucleon(NN) elastic cross section on the observables in heavy ion collisions in the Fermi energy domain are investigated within the framework of the ultrarelativistic quantum molec...The effects of the in-medium nucleon-nucleon(NN) elastic cross section on the observables in heavy ion collisions in the Fermi energy domain are investigated within the framework of the ultrarelativistic quantum molecular dynamics model. The results simulated using medium correction factors of F=σ_(NN)^(in-medium)/σ_(NN)^(free)=0.2,0.3,0.5,and the density-and momentum-dependent factor obtained from the FU3 FP1 parametrization are compared with the FOPI and INDRA experimental data. It is found that the calculations using the correction factors F=0.2 and 0.5 reproduce the experimental data(i.e.,collective flow and nuclear stopping) at 40 and 150 MeV/nucleon, respectively. Calculations with the FU3 FP1 parametrization can best fit these experimental data. These conclusions can be confirmed in both^(197)Au+^(197)Au and^(129)Xe+^(120)Sn.展开更多
The effect of several casting parameters on flowability of aluminium alloys is studied.It is found that fluidity increases linearly with the increase of pouring temperature and casting section thickness;the latent hea...The effect of several casting parameters on flowability of aluminium alloys is studied.It is found that fluidity increases linearly with the increase of pouring temperature and casting section thickness;the latent heat of vaporization is one of the most important properties of polystyrene which influences the molten metal flow.Also the mechanism of metal flowing stop is studied by means of dumping tests.The results show that for pure aluminium and aluminium alloys with narrow freezing range the molten metal flowing is stopped when a solidification shell which has enough strength to resist the effective pressure head is formed at the flowing metal front.The mechanism of flowing stop is much different from that in the traditional green sand casting.展开更多
Based on the difference between the online bus stop and the offline bus stop, two macro models are developed to describe the two types of bus stops. The numerical results show that the two models can qualitatively rep...Based on the difference between the online bus stop and the offline bus stop, two macro models are developed to describe the two types of bus stops. The numerical results show that the two models can qualitatively reproduce some complex phenomena resulted by the two types of bus stops and that the otttine bus stop is more effective than the online bus stop when the initial density is relatively low.展开更多
In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. A...In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. According to the concept of the compression factor and its differential equation, a stop-wave model is built. The theoretical value and the observed one are obtained by the survey data in Changchun city. The relative error between the two values is 20. 3%. The accuracy is improved 39% compared with the result from the traditional stop-wave model. The results show that the traffic flow is compressible, and the methods of research on gas compressibility is also applicable to the traffic flow. The stop-wave model obtained by the compression factor can better describe the phenomenon of the stop wave at a signalized intersection when compared with the traditional stop-wave model.展开更多
基金partly supported by the National Natural Science Foundation of China (Nos. U2032145 and 11875125)the National Key Research and Development Program of China (No. 2020YFE0202002)。
文摘In this study, the rapidity distribution, collective flows, and nuclear stopping power in ^(197)Au+^(197)Au collisions at intermediate energies were investigated using the ultrarelativistic quantum molecular dynamics(UrQMD) model with GEMINI++ code. The UrQMD model was adopted to simulate the dynamic evolution of heavy-ion collisions, whereas the GEMINI++ code was used to simulate the decay of primary fragments produced by UrQMD. The calculated results were compared with the INDRA and FOPI experimental data. It was found that the rapidity distribution, collective flows, and nuclear stopping power were affected to a certain extent by the decay of primary fragments, especially at lower beam energies. Furthermore, the experimental data of the collective flows and nuclear stopping power at the investigated beam energies were better reproduced when the sequential decay effect was included.
基金Supported by the National Natural Science Fundation of China
文摘The present paper contains the reaction mechanism of the rare earth complex with 2-(2-arsenophenylazo)-7-(2, 6-dichloro-4-fluoro-phenylazo)- 1, 8-dihydroxynaphthalene-3, 6-disulfonic acid (DCF-arsenazo) studied preliminarily with a fully automated stopped-flow analyzer. A method with a high sensitivity and selectivity is proposed for the simultaneous determination of samarium and gadolinium based on the differential kinetic reaction of the rare earth complex with DCF-arsenazo. Sm and Gd in their concentrated oxides were determined with the relative errors less than 6%.
基金This study was supported by the National Natural Science Foundation of China
文摘A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China （No. 20275027 and No. 20377032）.
文摘A highly sensitive stopped-flow spectrophotometry kinetic method was proposed for quantification phenoxyl radicals based on their accelerating effect on the oxidation of nicotinamide adenine dinucleotide （NADH）. Phenoxyl radicals generated from as low as 1×10^-8 mol/L 2,4-DCP can be readily detected with the proposed method and the detecting limit was 2.5×10^-9 mol/L.
基金Project(2012CB725400) supported by the National Basic Research Program of ChinaProjects(70901005, 71071016, 71131001) supported by the National Natural Science Foundation of ChinaProject(2011JBM055) supported by the Fundamental Research Funds for the Central Universities of China
文摘To determine how bus stop design influences mixed traffic operation near Chinese bus stops,a new theoretical method was developed by using additive-conflict-flows procedure.The procedure was extended from homogeneous traffic flow to mixed traffic flow.Based on the procedure and queuing theory,car capacity and speed models were proposed for three types of bus stops including curbside,bus bay and bicycle detour.The effects of various combinations of bus stop type,traffic volume,bus dwell time,and berth number on traffic operations were investigated.The results indicate that traffic volume,bus dwell time and berth number have negative effects on traffic operations for any type of bus stops.For different types of bus stops,at car volumes above approximately 200 vehicles per hour,the bus bay and bicycle detour designs provide more benefits than the curbside design.As traffic volume increases,the benefit firstly increases in uncongested conditions and then decreases in congested conditions.It reaches the maximum at car volumes nearly 1 100 vehicles per hour.The results can be used to aid in the selection of a preferred bus stop design for a given traffic volume in developing countries.
基金supported by the National Natural Science Foundation of China(Nos.11875125,11747312,11675066,and 11505057)the Zhejiang Provincial Natural Science Foundation of China(No.LY18A050002)
文摘The effects of the in-medium nucleon-nucleon(NN) elastic cross section on the observables in heavy ion collisions in the Fermi energy domain are investigated within the framework of the ultrarelativistic quantum molecular dynamics model. The results simulated using medium correction factors of F=σ_(NN)^(in-medium)/σ_(NN)^(free)=0.2,0.3,0.5,and the density-and momentum-dependent factor obtained from the FU3 FP1 parametrization are compared with the FOPI and INDRA experimental data. It is found that the calculations using the correction factors F=0.2 and 0.5 reproduce the experimental data(i.e.,collective flow and nuclear stopping) at 40 and 150 MeV/nucleon, respectively. Calculations with the FU3 FP1 parametrization can best fit these experimental data. These conclusions can be confirmed in both^(197)Au+^(197)Au and^(129)Xe+^(120)Sn.
文摘The effect of several casting parameters on flowability of aluminium alloys is studied.It is found that fluidity increases linearly with the increase of pouring temperature and casting section thickness;the latent heat of vaporization is one of the most important properties of polystyrene which influences the molten metal flow.Also the mechanism of metal flowing stop is studied by means of dumping tests.The results show that for pure aluminium and aluminium alloys with narrow freezing range the molten metal flowing is stopped when a solidification shell which has enough strength to resist the effective pressure head is formed at the flowing metal front.The mechanism of flowing stop is much different from that in the traditional green sand casting.
基金Supported by the Program for New Century Excellent Talents in University under Grant No.NCET-08-0038the National Natural Science Foundation of China under Grant Nos.70971007 and 70521001the State Key Basic Research Program of China under Grant No.2006CB705503
文摘Based on the difference between the online bus stop and the offline bus stop, two macro models are developed to describe the two types of bus stops. The numerical results show that the two models can qualitatively reproduce some complex phenomena resulted by the two types of bus stops and that the otttine bus stop is more effective than the online bus stop when the initial density is relatively low.
基金The National Basic Research Program of China (973Pro-gram)(No.2006CB705505)
文摘In order to describe the compressibility of traffic flows and determine the compression factors, the Mach number of gas dynamics is introduced, and the concept and the formula of the compression factor are obtained. According to the concept of the compression factor and its differential equation, a stop-wave model is built. The theoretical value and the observed one are obtained by the survey data in Changchun city. The relative error between the two values is 20. 3%. The accuracy is improved 39% compared with the result from the traditional stop-wave model. The results show that the traffic flow is compressible, and the methods of research on gas compressibility is also applicable to the traffic flow. The stop-wave model obtained by the compression factor can better describe the phenomenon of the stop wave at a signalized intersection when compared with the traditional stop-wave model.
