Fine particulate matter （PM2.5） samples were collected over two years in Xi＇an, China to investigate the relationships between the aerosol composition and the light absorption efficiency of black carbon （BC）. Rea...Fine particulate matter （PM2.5） samples were collected over two years in Xi＇an, China to investigate the relationships between the aerosol composition and the light absorption efficiency of black carbon （BC）. Real-time light attenuation of BC at 880 nm was measured with an aethalometer. The mass concentrations and elemental carbon （EC） contents of PM2.5 were obtained, and light attenuation cross-sections （σATN） of PM2.5 BC were derived. The mass of EC contributed -5% to PM2.5 on average. BC σATN exhibited pronounced seasonal variability with values averaging 18.6, 24.2,16.4, and 26.0 m^2/g for the spring, summer, autumn, and winter, respectively, while averaging 23.0 m^2/g overall. σATN varied inversely with the ratios of EC/PM2.5, EC/[SO4^2- ], and EC/[NO3-]. This study of the variability in σATN illustrates the complexity of the interactions among the aerosol constituents in northern China and documents certain effects of the high EC, dust, sulfate and nitrate loadings on light attenuation.展开更多
The attenuation of lateral propagating light （LPL） in sea ice was measured using an artificial light source in the Canadian Arctic during the 2007/2008 winter. The apparent attenuation coefficientμ（λ）for lateral...The attenuation of lateral propagating light （LPL） in sea ice was measured using an artificial light source in the Canadian Arctic during the 2007/2008 winter. The apparent attenuation coefficientμ（λ）for lateral prop-agating light was obtained from the measured logarithmic relative variation rate. In this study an analytical solution based on the strict optical theories is developed to validate the measured result. There is a good consistency between theoretical solution and measured data, by which a quite simple but very rigorous relationship among the light source, measurement geometry, and measured irradiance is established. The attenuation coefficients acquired by measurement and theory are the diffusion attenuation as an apparent optical property of ice, independent of the light source and shining condition. The attenuation ability of sea ice should be caused by the microstructure of sea ice, such as crystal size, ice density, brine volume, air inclusion, etc. It also includes the leak from both interfaces by directional scattering. It is verified that the measuring approach is operational and accurate to measure the attenuation of the LPL. The solution from this study did not tell the connection among the extinction and the inclusions of sea ice theoretically be-cause of insufficient understanding.展开更多
This paper deals with a systematical analysis and an algorithm of attenuation characteristics of a light attenuator combined by n pieces of polarizers （n-LACP） whose extinction ratios are different from each other. ...This paper deals with a systematical analysis and an algorithm of attenuation characteristics of a light attenuator combined by n pieces of polarizers （n-LACP） whose extinction ratios are different from each other. The attenuation ratio expression of a two-LACP is deduced. We find that the monotonic attenuation interval depends on the first polarizer and that the attenuation range depends on the second one. For the three-LACP, a method for obtaining a monotonic attenuation interval is proposed. Moreover, the attenuation ratio expression is demonstrated. Analysis and experiment show that when the initial status of the three-LACP is at the maximum output, if the second or third polarizer rotates alone, the minimum attenuation ratios can reach K2^-1 and K3^-1, respectively, and if the first polarizer rotates, a minimum attenuation ratio of K2^-1K3^-1 can be obtained （K1, K2 and K3 represent the extinction ratios of the three polarizers in turn）. Furthermore, the attenuation ratio expression of n-LACP and the relevant attenuation characteristics are proposed. The minimum attenuation ratio of an n-LACP is （K2K3 ... Kn）-1.展开更多
Crystallization kinetics of syndiotactic polypropylene(sPP)was observed by light attenuation measurements. The initial stages of temperature dependent sPP crystallization fall in the range of Rayleigh scattering and R...Crystallization kinetics of syndiotactic polypropylene(sPP)was observed by light attenuation measurements. The initial stages of temperature dependent sPP crystallization fall in the range of Rayleigh scattering and Rayleigh-Debye- Gans scattering.Initial time and growth time of crystallization were obtained,and the trend of crystallization temperature dependent linear attenuation coefficient on the radius and the index of the refraction of the spherulite were evaluated.展开更多
Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of l...Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of light nucleus reaction(STLN)is developed to calculate the double-differential cross-sections of the outgoing neutron and light charged particles for the proton-induced^(6) Li reaction.A significant difference is observed between the p+^(6) Li and p+^(7) Li reactions owing to the discrepancies in the energy-level structures of the targets.The reaction channels,including sequential and simultaneous emission processes,are analyzed in detail.Taking the double-differential cross-sections of the outgoing proton as an example,the influence of contaminations(such as^(1) H,^(7)Li,^(12)C,and^(16)O)on the target is identified in terms of the kinetic energy of the first emitted particles.The optical potential parameters of the proton are obtained by fitting the elastic scattering differential cross-sections.The calculated total double-differential cross-sections of the outgoing proton and deuteron at E_(p)=14 MeV agree well with the experimental data for different outgoing angles.Simultaneously,the mixed double differential cross-sections of^(3) He andαare in good agreement with the measurements.The agreement between the measured data and calculated results indicates that the two-body and three-body breakup reactions need to be considered,and the pre-equilibrium reaction mechanism dominates the reaction processes.Based on the STLN model,a PLUNF code for the p+^(6) Li reaction is developed to obtain an ENDF-6-formatted file of the double-differential cross-sections of the nucleon and light composite charged particles.展开更多
The amount of photosynthetic radiation inter- cepted by a crop is a function of the incident solar radiation on the plants, the leaf area index （LAI）, and the light extinction coefficient （k）. We quantified LAI an...The amount of photosynthetic radiation inter- cepted by a crop is a function of the incident solar radiation on the plants, the leaf area index （LAI）, and the light extinction coefficient （k）. We quantified LAI and k in stands of black wattle （Acacia mearnsii De Wild.） over a 7-year growth cycle at two locations in the state of Rio Grande do Sul, Brazil. Our study was conducted in commercial stands in agroecological regions with high densities of black wattle plantations. LAI was calculated as the ratio between the leaf area of a tree and its planting space, and k was derived from Beer＇s law. LAI depends on the planting site and stand age. Between the two sites, the LAI was similar over time, the amount of variation differed. Values of k depended only on stand age, with the highest average observed for stands up to 5 years old. The trend of k during the plantation cycle was inversely proportional to LAI and was correlated with LAI, leaf area, leaf dry mass, canopy volume, height, branches dry mass, total dry mass, and crown diameter.展开更多
With the application of energy-saving, environmental and durable LED lighting products, the reliability testing has become a pivot point for the large scale industrialization and popularization. The paper briefly intr...With the application of energy-saving, environmental and durable LED lighting products, the reliability testing has become a pivot point for the large scale industrialization and popularization. The paper briefly introduces two methods to be respectively applied in the accelerated depreciatinn lesting for the luminous flex of LED lighting products and the life of outdoor LED-driving power, which can sharply shorten the time for lifetime lest. providing references for the LED lighting products＇ reliability evaluation.展开更多
在“双碳”目标背景下,碳捕捉、利用及封存(carbon capture,utilization and storage,CCUS)是燃煤电厂实现烟气脱碳的最理想策略。在CCUS技术中,微藻固碳是极具潜力的CO_(2)利用方式。微藻不仅生长速率快而且可以将CO_(2)转化为高附加...在“双碳”目标背景下,碳捕捉、利用及封存(carbon capture,utilization and storage,CCUS)是燃煤电厂实现烟气脱碳的最理想策略。在CCUS技术中,微藻固碳是极具潜力的CO_(2)利用方式。微藻不仅生长速率快而且可以将CO_(2)转化为高附加值的微藻产/制品。然而,由于光能和CO_(2)利用率低,微藻固碳目前的经济可行性还达不到商业化要求,仍需进一步研究。基于国内外的相关研究,本文首先剖析了微藻悬浮液中烟气溶解、转化、被利用的过程以及光衰减现象;讨论了CO_(2)、光质及其强度等因素对微藻生长和固碳性能的影响。其次,从选育高固碳能力藻种、增强CO_(2)传质和优化光供给策略三方面综述了提高微藻CO_(2)固定效率和光合效率的方法;扼要地阐明了其中原理,以期为后续研究提供思路。最后,展望了微藻生物质的利用方向,为微藻固碳在实现我国“双碳”目标过程中的应用提供了参考。展开更多
This research directly supported the author’s thesis work in partial fulfilment of Master of Science in biology from the University of North Texas(United States)from August 1996 to September 1997.Two sites at Lake Ra...This research directly supported the author’s thesis work in partial fulfilment of Master of Science in biology from the University of North Texas(United States)from August 1996 to September 1997.Two sites at Lake Ray Roberts,Denton County,Texas(United States)were examined and contrasted for productivity.The site located in the pelagic zone exhibited a slight,thermal gradient with no stratification,and a slightly stratified clinograde oxygen profile which is typical for summer-stratified eutrophic lakes.The site located in the shallow,littoral zone exhibited high,increasing turbidity with depth,marked by shallow light attenuation through the water column.Temperature was constant at every depth in the littoral site,with a slight,clinograde oxygen profile,typical for shallow,littoral areas subject to wind-induced mixing.Volume estimations of chlorophyll-α shows a strong presence in the euphotic zone,indicating photosynthesis occurs until approximately 2.2 m below the surface.The shallow,littoral site showed the basic signs of higher productivity than the open,pelagic site.展开更多
基金supported by the projects from the National Natural Science Foundation of China(41230641)the Ministry of Science & Technology(2012BAH31B03,201209007)the Shaanxi Government(2012KTZB03-01-01,2011KTCQ03-04)
文摘Fine particulate matter （PM2.5） samples were collected over two years in Xi＇an, China to investigate the relationships between the aerosol composition and the light absorption efficiency of black carbon （BC）. Real-time light attenuation of BC at 880 nm was measured with an aethalometer. The mass concentrations and elemental carbon （EC） contents of PM2.5 were obtained, and light attenuation cross-sections （σATN） of PM2.5 BC were derived. The mass of EC contributed -5% to PM2.5 on average. BC σATN exhibited pronounced seasonal variability with values averaging 18.6, 24.2,16.4, and 26.0 m^2/g for the spring, summer, autumn, and winter, respectively, while averaging 23.0 m^2/g overall. σATN varied inversely with the ratios of EC/PM2.5, EC/[SO4^2- ], and EC/[NO3-]. This study of the variability in σATN illustrates the complexity of the interactions among the aerosol constituents in northern China and documents certain effects of the high EC, dust, sulfate and nitrate loadings on light attenuation.
基金The Global Change Research Program of China under contract No.2015CB953900the Key Program of National Natural Science Foundation of China under contract No.41330960
文摘The attenuation of lateral propagating light （LPL） in sea ice was measured using an artificial light source in the Canadian Arctic during the 2007/2008 winter. The apparent attenuation coefficientμ（λ）for lateral prop-agating light was obtained from the measured logarithmic relative variation rate. In this study an analytical solution based on the strict optical theories is developed to validate the measured result. There is a good consistency between theoretical solution and measured data, by which a quite simple but very rigorous relationship among the light source, measurement geometry, and measured irradiance is established. The attenuation coefficients acquired by measurement and theory are the diffusion attenuation as an apparent optical property of ice, independent of the light source and shining condition. The attenuation ability of sea ice should be caused by the microstructure of sea ice, such as crystal size, ice density, brine volume, air inclusion, etc. It also includes the leak from both interfaces by directional scattering. It is verified that the measuring approach is operational and accurate to measure the attenuation of the LPL. The solution from this study did not tell the connection among the extinction and the inclusions of sea ice theoretically be-cause of insufficient understanding.
基金Project supported by the Technological Innovation Project of Air-to-Air Missile Institute of China (Grant No.5S85000FS)
文摘This paper deals with a systematical analysis and an algorithm of attenuation characteristics of a light attenuator combined by n pieces of polarizers （n-LACP） whose extinction ratios are different from each other. The attenuation ratio expression of a two-LACP is deduced. We find that the monotonic attenuation interval depends on the first polarizer and that the attenuation range depends on the second one. For the three-LACP, a method for obtaining a monotonic attenuation interval is proposed. Moreover, the attenuation ratio expression is demonstrated. Analysis and experiment show that when the initial status of the three-LACP is at the maximum output, if the second or third polarizer rotates alone, the minimum attenuation ratios can reach K2^-1 and K3^-1, respectively, and if the first polarizer rotates, a minimum attenuation ratio of K2^-1K3^-1 can be obtained （K1, K2 and K3 represent the extinction ratios of the three polarizers in turn）. Furthermore, the attenuation ratio expression of n-LACP and the relevant attenuation characteristics are proposed. The minimum attenuation ratio of an n-LACP is （K2K3 ... Kn）-1.
基金This work is supported by the National Natural Science Foundation of China(Nos.50773082,20574069,20490220)subsidized by the Special Funds for National Basic Research Program of China(No.2003CB615600)X-ray scattering experiments were conducted in the framework of a HASYLAB project(No.Ⅱ-05-011).
文摘Crystallization kinetics of syndiotactic polypropylene(sPP)was observed by light attenuation measurements. The initial stages of temperature dependent sPP crystallization fall in the range of Rayleigh scattering and Rayleigh-Debye- Gans scattering.Initial time and growth time of crystallization were obtained,and the trend of crystallization temperature dependent linear attenuation coefficient on the radius and the index of the refraction of the spherulite were evaluated.
基金supported by the National Natural Science Foundation of China(No.12065003)the Guangxi Key R&D Project(2023AB07029)+1 种基金the Scientific Research and Technology Development Project of Guilin(20210104-2)the Central Government Guides Local Scientific and Technological Development Funds of China(Guike ZY22096024)。
文摘Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of light nucleus reaction(STLN)is developed to calculate the double-differential cross-sections of the outgoing neutron and light charged particles for the proton-induced^(6) Li reaction.A significant difference is observed between the p+^(6) Li and p+^(7) Li reactions owing to the discrepancies in the energy-level structures of the targets.The reaction channels,including sequential and simultaneous emission processes,are analyzed in detail.Taking the double-differential cross-sections of the outgoing proton as an example,the influence of contaminations(such as^(1) H,^(7)Li,^(12)C,and^(16)O)on the target is identified in terms of the kinetic energy of the first emitted particles.The optical potential parameters of the proton are obtained by fitting the elastic scattering differential cross-sections.The calculated total double-differential cross-sections of the outgoing proton and deuteron at E_(p)=14 MeV agree well with the experimental data for different outgoing angles.Simultaneously,the mixed double differential cross-sections of^(3) He andαare in good agreement with the measurements.The agreement between the measured data and calculated results indicates that the two-body and three-body breakup reactions need to be considered,and the pre-equilibrium reaction mechanism dominates the reaction processes.Based on the STLN model,a PLUNF code for the p+^(6) Li reaction is developed to obtain an ENDF-6-formatted file of the double-differential cross-sections of the nucleon and light composite charged particles.
文摘The amount of photosynthetic radiation inter- cepted by a crop is a function of the incident solar radiation on the plants, the leaf area index （LAI）, and the light extinction coefficient （k）. We quantified LAI and k in stands of black wattle （Acacia mearnsii De Wild.） over a 7-year growth cycle at two locations in the state of Rio Grande do Sul, Brazil. Our study was conducted in commercial stands in agroecological regions with high densities of black wattle plantations. LAI was calculated as the ratio between the leaf area of a tree and its planting space, and k was derived from Beer＇s law. LAI depends on the planting site and stand age. Between the two sites, the LAI was similar over time, the amount of variation differed. Values of k depended only on stand age, with the highest average observed for stands up to 5 years old. The trend of k during the plantation cycle was inversely proportional to LAI and was correlated with LAI, leaf area, leaf dry mass, canopy volume, height, branches dry mass, total dry mass, and crown diameter.
文摘With the application of energy-saving, environmental and durable LED lighting products, the reliability testing has become a pivot point for the large scale industrialization and popularization. The paper briefly introduces two methods to be respectively applied in the accelerated depreciatinn lesting for the luminous flex of LED lighting products and the life of outdoor LED-driving power, which can sharply shorten the time for lifetime lest. providing references for the LED lighting products＇ reliability evaluation.
文摘在“双碳”目标背景下,碳捕捉、利用及封存(carbon capture,utilization and storage,CCUS)是燃煤电厂实现烟气脱碳的最理想策略。在CCUS技术中,微藻固碳是极具潜力的CO_(2)利用方式。微藻不仅生长速率快而且可以将CO_(2)转化为高附加值的微藻产/制品。然而,由于光能和CO_(2)利用率低,微藻固碳目前的经济可行性还达不到商业化要求,仍需进一步研究。基于国内外的相关研究,本文首先剖析了微藻悬浮液中烟气溶解、转化、被利用的过程以及光衰减现象;讨论了CO_(2)、光质及其强度等因素对微藻生长和固碳性能的影响。其次,从选育高固碳能力藻种、增强CO_(2)传质和优化光供给策略三方面综述了提高微藻CO_(2)固定效率和光合效率的方法;扼要地阐明了其中原理,以期为后续研究提供思路。最后,展望了微藻生物质的利用方向,为微藻固碳在实现我国“双碳”目标过程中的应用提供了参考。
文摘This research directly supported the author’s thesis work in partial fulfilment of Master of Science in biology from the University of North Texas(United States)from August 1996 to September 1997.Two sites at Lake Ray Roberts,Denton County,Texas(United States)were examined and contrasted for productivity.The site located in the pelagic zone exhibited a slight,thermal gradient with no stratification,and a slightly stratified clinograde oxygen profile which is typical for summer-stratified eutrophic lakes.The site located in the shallow,littoral zone exhibited high,increasing turbidity with depth,marked by shallow light attenuation through the water column.Temperature was constant at every depth in the littoral site,with a slight,clinograde oxygen profile,typical for shallow,littoral areas subject to wind-induced mixing.Volume estimations of chlorophyll-α shows a strong presence in the euphotic zone,indicating photosynthesis occurs until approximately 2.2 m below the surface.The shallow,littoral site showed the basic signs of higher productivity than the open,pelagic site.
