OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma medicine.However,experimental st...OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma medicine.However,experimental studies on how the gas content affects the postdischarge temporal evolutions of OH and O in the noble gas ns-NAPP are very limited.In this work,the effect of the percentages of O_(2),N_(2),and H_(2)O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence(LIF)method.The results show that the productions of OH and O increase and then decrease with the increase of O_(2)percentage.Both OH and O densities reach their maximum when about 0.8%O_(2)is added.Further increase of the O_(2)concentration results in a decrease of the initial densities of both OH and O,and leads to their faster decay.The increase of N_(2)percentage also results in the increase and then decrease of the OH and O densities,but the change is smaller.Furthermore,when the H_(2)O concentration is increased from 100 to 3000 ppm,the initial OH density increases slightly,but the OH density decays much faster,while the initial density of O decreases with the increase of the H_(2)O concentration.After analysis,it is found that OH and O are mainly produced through electron collisional dissociation.O(^(1)D)is critical for OH generation.O_(3)accelerates the consumption processes of OH and O at high O_(2)percentage.The addition of H_(2)O in the NAPP considerably enhances the electronegativity,while it decreases the overall plasma reactivity,accelerates the decay of OH,and reduces the O atom density.展开更多
The temporal property of grey screening spatial solitons due to two-photon photorefractive effect in lowamplitude regime is analyzed. The results indicate that a broad solitons is generated at the beginning, and as ti...The temporal property of grey screening spatial solitons due to two-photon photorefractive effect in lowamplitude regime is analyzed. The results indicate that a broad solitons is generated at the beginning, and as time evolves, the intensity width of grey solitons decreases monotonically to a minimum value toward steady state. In the same propagation time, the FWHM of solitons decreases with p increasing or m decreasing. Moreover, the formation time of solitons is independent of p and m. The time is close to a constant determined by the dielectric relaxation time.展开更多
With the rapid development of the Internet,the amount of data recorded on the Internet has increased dramatically.It is becoming more and more urgent to effectively obtain the specific information we need from the vas...With the rapid development of the Internet,the amount of data recorded on the Internet has increased dramatically.It is becoming more and more urgent to effectively obtain the specific information we need from the vast ocean of data.In this study,we propose a novel collaborative filtering algorithm for generating recommendations in e-commerce.This study has two main innovations.First,we propose a mechanismthat embeds temporal behavior information to find a neighbor set in which each neighbor has a very significant impact on the current user or item.Second,we propose a novel collaborative filtering algorithm by injecting the neighbor set into probability matrix factorization.We compared the proposed method with several state-of-the-art alternatives on real datasets.The experimental results show that our proposed method outperforms the prevailing approaches.展开更多
High-spectral resolution infrared sounders on board satellites can measure atmospheric trace gases confined to the planetary boundary layer(PBL).However,their sensitivity to the PBL depends on the temperature differen...High-spectral resolution infrared sounders on board satellites can measure atmospheric trace gases confined to the planetary boundary layer(PBL).However,their sensitivity to the PBL depends on the temperature difference between the surface and the atmosphere,the so-called thermal contrast(TC).After reviewing the physical aspects of TC and how it drives measurement sensitivity,we characterize the global and temporal behavior of TC in clear-sky conditions.Combining land surface temperatures from the Copernicus Global Land Services dataset with air temperatures from the European Centre for Medium-Range Weather Forecasts reanalysis v5,we obtain global monthly averages of TC at high spatial(31 km)and temporal(1 h)resolution.TCs are analyzed as a function of time of the day,time of the year,location and land cover.Daytime maxima are observed from 1130 to 1330 local time,from 5-10 K in winter to 10-30 K in summer.A large dependency on land cover type is observed,both in the magnitude of the daily variations,and in the seasonality.For bare soils,shrublands,sparse and herbaceous vegetation,a maximum is seen in summer with daily TC amplitudes over 30 K.In contrast,for forests,wetlands,and croplands,the seasonal maximum occurs in spring,with daily variations below 15 K.Nighttime TCs typically range between−5 and−10 K.Occasionally,very favorable nighttime measurement conditions occur during winter and autumn due to large temperature inversions.Throughout the paper,we illustrate important concepts by means of satellite observations of NH3 over the Po Valley(Italy).展开更多
基金supported by National Natural Science Foundation of China(Nos.52130701 and 51977096)the National Key Research and Development Program of China(No.2021YFE0114700)。
文摘OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma medicine.However,experimental studies on how the gas content affects the postdischarge temporal evolutions of OH and O in the noble gas ns-NAPP are very limited.In this work,the effect of the percentages of O_(2),N_(2),and H_(2)O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence(LIF)method.The results show that the productions of OH and O increase and then decrease with the increase of O_(2)percentage.Both OH and O densities reach their maximum when about 0.8%O_(2)is added.Further increase of the O_(2)concentration results in a decrease of the initial densities of both OH and O,and leads to their faster decay.The increase of N_(2)percentage also results in the increase and then decrease of the OH and O densities,but the change is smaller.Furthermore,when the H_(2)O concentration is increased from 100 to 3000 ppm,the initial OH density increases slightly,but the OH density decays much faster,while the initial density of O decreases with the increase of the H_(2)O concentration.After analysis,it is found that OH and O are mainly produced through electron collisional dissociation.O(^(1)D)is critical for OH generation.O_(3)accelerates the consumption processes of OH and O at high O_(2)percentage.The addition of H_(2)O in the NAPP considerably enhances the electronegativity,while it decreases the overall plasma reactivity,accelerates the decay of OH,and reduces the O atom density.
基金Supported by the Science and Technology Development Foundation of Higher Education of Shanxi Province under Grant No.200611042 Basic Research Foundation of Yuncheng University under Grant No.JC-2009003
文摘The temporal property of grey screening spatial solitons due to two-photon photorefractive effect in lowamplitude regime is analyzed. The results indicate that a broad solitons is generated at the beginning, and as time evolves, the intensity width of grey solitons decreases monotonically to a minimum value toward steady state. In the same propagation time, the FWHM of solitons decreases with p increasing or m decreasing. Moreover, the formation time of solitons is independent of p and m. The time is close to a constant determined by the dielectric relaxation time.
基金supported by the National Natural Science Foundation of China under Grant Nos.81873915,61702225 and 61806026Ministry of Science and Technology Key Research and Development Program of China under Grant No.2018YFC0116902+3 种基金by the Natural Science Foundation of Jiangsu Province under Grant No.BK20180956by the 2018 Six Talent Peaks Project of Jiangsu Province under Grant No.XYDXX-127by the Science and Technology demonstration project of social development of Wuxi under Grant WX18IVJN002by the Philosophy and Social Science Foundation of Jiangsu Province(18YSC009).
文摘With the rapid development of the Internet,the amount of data recorded on the Internet has increased dramatically.It is becoming more and more urgent to effectively obtain the specific information we need from the vast ocean of data.In this study,we propose a novel collaborative filtering algorithm for generating recommendations in e-commerce.This study has two main innovations.First,we propose a mechanismthat embeds temporal behavior information to find a neighbor set in which each neighbor has a very significant impact on the current user or item.Second,we propose a novel collaborative filtering algorithm by injecting the neighbor set into probability matrix factorization.We compared the proposed method with several state-of-the-art alternatives on real datasets.The experimental results show that our proposed method outperforms the prevailing approaches.
基金funding from the Belgian State Federal Office for Scientific,Technical and Cultural Affairs(Prodex HIRS)the Air Liquide Foundation(TAPIR project)+3 种基金supported by the FED-tWIN project ARENBERG(“Assessing the Reactive Nitrogen Budget and Emissions at Regional and Global Scales”)funded through the Belgian Science Policy Office(BELSPO)supported by the Belgian F.R.S.-FNRSsupport from a FRIA(Fund for scientific Research in Industry and Agriculture)grant from the Belgian F.R.S-FNRS.
文摘High-spectral resolution infrared sounders on board satellites can measure atmospheric trace gases confined to the planetary boundary layer(PBL).However,their sensitivity to the PBL depends on the temperature difference between the surface and the atmosphere,the so-called thermal contrast(TC).After reviewing the physical aspects of TC and how it drives measurement sensitivity,we characterize the global and temporal behavior of TC in clear-sky conditions.Combining land surface temperatures from the Copernicus Global Land Services dataset with air temperatures from the European Centre for Medium-Range Weather Forecasts reanalysis v5,we obtain global monthly averages of TC at high spatial(31 km)and temporal(1 h)resolution.TCs are analyzed as a function of time of the day,time of the year,location and land cover.Daytime maxima are observed from 1130 to 1330 local time,from 5-10 K in winter to 10-30 K in summer.A large dependency on land cover type is observed,both in the magnitude of the daily variations,and in the seasonality.For bare soils,shrublands,sparse and herbaceous vegetation,a maximum is seen in summer with daily TC amplitudes over 30 K.In contrast,for forests,wetlands,and croplands,the seasonal maximum occurs in spring,with daily variations below 15 K.Nighttime TCs typically range between−5 and−10 K.Occasionally,very favorable nighttime measurement conditions occur during winter and autumn due to large temperature inversions.Throughout the paper,we illustrate important concepts by means of satellite observations of NH3 over the Po Valley(Italy).
