Flame temperature distribution is one of the most important characteristic parameters in combustion research. The emission method is a good way to measure the luminous flame temperature field. The maximum entropy meth...Flame temperature distribution is one of the most important characteristic parameters in combustion research. The emission method is a good way to measure the luminous flame temperature field. The maximum entropy method is introduced to the temperature distribution measurement of a luminous flame using the emission method. A simplified mathematical model was derived by combining the thermal radiation theory, reconstruction algorithm and maximum entropy method. Suitable parameters were selected in the computing process. Good experimental results were obtained with pulverized coal flames.[展开更多
An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO_3 acid system with a high-pressure closed digestion method（HPCD）, is stud...An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO_3 acid system with a high-pressure closed digestion method（HPCD）, is studied by an inductively coupled plasma optical emission spectrometry（ICP-OES） and an inductively coupled plasma mass spectrometry（ICP-MS）. The operating parameters of the instruments are optimized, and the optimal analytical parameters are determined. The influences of optical spectrum and mass spectrum interferences, digestion methods and acid systems on the analytical results are investigated. The optimal spectral lines and isotopes are chosen, and internal standard element of rhodium is selected to compensate for matrix effects and analytical signals drifting. Compared with the methods of an electric heating plate digestion and a microwave digestion, a high-pressure closed digestion method is optimized with less acid, complete digestion,less damage for digestion process. The marine geological samples are dissolved completely by a HF-HCl-HNO_3 system, the relative error（RE） for the analytical results are all less than 6.0%. The method detection limits are 2–40μg/g by the ICP-OES, and 6–80 ng/g by ICP-MS. The methods are used to determine the marine sediment reference materials（GBW07309, GBW07311, GBW07313）, rock reference materials（GBW07103, GBW07104,GBW07105）, and cobalt-rich crust reference materials（GBW07337, GBW07338, GBW07339）, the obtained analytical results are in agreement with the certified values, and both of the relative standard deviation（RSD） and the relative error（RE） are less than 6.0%. The analytical method meets the requirements for determining 52 elements contents of bulk marine geological samples.展开更多
The purpose of the work is to identify the acoustic emission （AE） signal in the melt and from the interphase during the crystal growth and to establish the connection between issue parameters： the number of signal ...The purpose of the work is to identify the acoustic emission （AE） signal in the melt and from the interphase during the crystal growth and to establish the connection between issue parameters： the number of signal events of frequency and the signal power with the growth conditions of temperature gradient and crystallization rate. Experiments on single crystal growth were carried out using hardware and software system which allows to perform spectral Fourier analysis of AE signals and to simultaneously remove the cooling curve for the entire period of crystallization. On the basis of spectral analysis of AE signals, a theoretical model of clusters in the aluminum melt was designed. The experimental results indicate an uneven abrupt advancement of the interface according to the configuration of each individual cluster.展开更多
In this paper,nitrogen dielectric barrier discharge（DBD） plasma was generated in a quartz tube with coaxial wire-cylinder electrodes at atmospheric pressure.By varying the nitrogen gas flow（FN） in the range of 0-1...In this paper,nitrogen dielectric barrier discharge（DBD） plasma was generated in a quartz tube with coaxial wire-cylinder electrodes at atmospheric pressure.By varying the nitrogen gas flow（FN） in the range of 0-1 m3/h,the plasma optical emission spectra（OES） were measured and studied.The vibration（T_（vib）） and rotation temperature（T_（rot）） of nitrogen were obtained,by fitting the rovibronic bands of N_2（C^3∏_u-B^3∏_g,0-1）,and by the Boltzmann plot method for purposes of comparison.T_（vib） increased up to 2481 K with increasing nitrogen flow till0.2 m3/h,and then decreased with further increasing FN,while Trot decreased monotonously and approached to-350 K for FN ≥ 0.6 m^3/h.The intensity of N_2（C^3∏_u-B^3∏_g,0-0,1-0,0-3） and N_2~＋（B^2∑_u~＋-X^2Σ_g~＋,0-0） exhibited similar evolution with increasing FN to those of the T_（vib） and Trot,respectively.The discharge photos revealed that the discharge filaments gradually decreased with increasing FN,and eventually disappeared,which implied that a discharge mode transition emerged with increasing FN.The possible mechanism for the discharge mode transition is studied in detail according to the vibration（T_（vib）） and rotation temperature（T_（rot）） of nitrogen.展开更多
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope （LAMOST） has released more than two million spectra, which provide the opportunity to search for double-peaked narrow emission line （NEL） galaxies and ...The Large Sky Area Multi-Object Fiber Spectroscopic Telescope （LAMOST） has released more than two million spectra, which provide the opportunity to search for double-peaked narrow emission line （NEL） galaxies and active galactic nuclei （AGNs）. The double-peaked narrow-line profiles can be well modeled by two velocity components, respectively blueshifted and redshifted with respect to the sys- temic recession velocity. This paper presents 20 double-peaked NEL galaxies and AGNs found from LAMOST DR1 using a search method based on a multi-Gaussian fit of the narrow emission lines. Among them, ten have already been published by other authors, either listed as genuine double-peaked NEL objects or as asymmetric NEL objects, and the remaining ten are original discoveries. We discuss some pos- sible origins for the double-peaked narrow-line features, such as interaction between jet and narrow line regions, interaction with companion galaxies, and black hole bina- ries. Spatially resolved optical imaging and/or follow-up observations in other spectral bands are needed to further discuss the physical mechanisms at work.展开更多
The extended “STIRPAT” model and the GM(1,1) model are used to predict the factors influencing inter-provincial carbon emission intensity and carbon intensity in China respectively. In this paper, based on the colla...The extended “STIRPAT” model and the GM(1,1) model are used to predict the factors influencing inter-provincial carbon emission intensity and carbon intensity in China respectively. In this paper, based on the collation of inter-provincial carbon emission data, the extended “STIRPAT” model is formulated for carbon dioxide emissions and carbon intensity emissions, and the Hausman test is used to determine the influence form of the models. The main influencing factors of carbon intensity were identified: economic development level, energy intensity, and energy consumption structure. The paper constructs GM(1,1) model for carbon emission intensity from 2010-2019 using the gray prediction method,and calculates the carbon emission intensity of China’s inter-provincial 2022 by residual test, correlation test, variance, and small error probability test, and then predicts the carbon demand of each province and city in 2022 according to the expected average annual growth rate, and finally concludes that using carbon emission intensity as the carbon emission reduction target of each region, and it cannot fundamentally solve the problem of carbon pollution in China. Compared to the regional carbon emission reduction target, there is a greater degree of regional imbalance in carbon intensity between provinces in China, and the target of reducing carbon emission intensity somehow avoids the fact that the carbon emission reduction intensity target can be achieved without reducing the absolute amount of carbon emissions that continue to increase. The focus of achieving the “double carbon” target lies in the reduction of total carbon emissions, and the target of reducing carbon intensity will eventually be transformed into a binding target of total carbon emissions in the process of implementation, so attention should be shifted from recessiontype carbon reduction and efficiency-type carbon reduction to innovative carbon reduction. It is necessary to increase investment in renewable energy, and gradually expand the scope of application of photovoltaic, and wind power to ensure the reduction of total carbon emissions.展开更多
Developing an anthropogenic carbon dioxides(CO_(2))emissions monitoring and verification support(MVS)capacity is essential to support the Global Stocktake(GST)and ratchet up Nationally Determined Contributions(NDCs).T...Developing an anthropogenic carbon dioxides(CO_(2))emissions monitoring and verification support(MVS)capacity is essential to support the Global Stocktake(GST)and ratchet up Nationally Determined Contributions(NDCs).The 2019 IPCC refinement proposes top-down inversed CO_(2)emissions,primarily from fossil fuel(FFCO_(2)),as a viable emission dataset.Despite substantial progress in directly inferring FFCO_(2)emissions from CO_(2)observations,substantial challenges remain,particularly in distinguishing local CO_(2)enhancements from the high background due to the long atmospheric lifetime.Alternatively,using short-lived and co-emitted nitrogen dioxide(NO_(2))as a proxy in FFCO_(2)emission inversion has gained prominence.This methodology is broadly categorized into plume-based and emission ratios(ERs)-based inversion methods.In the plume-based methods,NO_(2)observations act as locators,constraints,and validators for deciphering CO_(2)plumes downwind of sources,typically at point source and city scales.The ERs-based inversion approach typically consists of two steps:inferring NO_(2)-based nitrogen oxides(NO_(x))emissions and converting NO_(x)to CO_(2)emissions using CO_(2)-to-NO_(x)ERs.While integrating NO_(2)observations into FFCO_(2)emission inversion offers advantages over the direct CO_(2)-based methods,uncertainties persist,including both structural and data-related uncertainties.Addressing these uncertainties is a primary focus for future research,which includes deploying nextgeneration satellites and developing advanced inversion systems.Besides,data caveats are necessary when releasing data to users to prevent potential misuse.Advancing NO_(2)-based CO_(2)emission inversion requires interdisciplinary collaboration across multiple communities of remote sensing,emission inventory,transport model improvement,and atmospheric inversion algorithm development.展开更多
Dust events occurred frequently in Beijing in recent years. In this work, 120 aerosol samples were collected in two typical dust events (21-22 March and 15 May) and a non-dust period in Beijing from March to May 2001....Dust events occurred frequently in Beijing in recent years. In this work, 120 aerosol samples were collected in two typical dust events (21-22 March and 15 May) and a non-dust period in Beijing from March to May 2001. Samples were analyzed for major elemental components by the Proton Induced X-ray Emission (PIXE) method. Results show that the enrichment factors of crustal elements such as Mg, Al, and Ti had little differences between the dust period and the non-dust period in Beijing, while the enrichment factors of other elements that have a relation to anthropogenic emissions were very low during the dust period. The results derived by using multivariate factor analysis from the observation data show that the sources such as soil dust, industry, and fuel combustion were among the major contributors to the particles in Beijing.展开更多
The total emission control method based on atmospheric environmental capacity is the most effective in air pollution mitigation. The atmospheric environmental capacities of SO2 on representative days over Lanzhou are ...The total emission control method based on atmospheric environmental capacity is the most effective in air pollution mitigation. The atmospheric environmental capacities of SO2 on representative days over Lanzhou are estimated using the numerical models RAMS, HYPACT and a linear programming model, according to the national ambient air quality standard of China （NAAQSCHN）. The results show that the fields of meteorological elements and SO2 simulated by the models agree reasonably well with observations. The atmospheric environmental capacity of SO2 over Lanzhou is around 111.7 × 10^3 kg d^-1, and in order to meet the air quality level Ⅱ of the NAAQSCHN, SO2 emissions need to be reduced by 20%.展开更多
The safety of rail is very important for the development of high speed railway, and it is necessary to investigate the features of inner cracks in rail. In order to obtain the features of Acoustic Emission （AE） sour...The safety of rail is very important for the development of high speed railway, and it is necessary to investigate the features of inner cracks in rail. In order to obtain the features of Acoustic Emission （AE） sources of inner cracks in rail, AE sources with different types, depths and propagation distances are examined for crack in rail. The finite element method is utilized to model the rail with cracks and the results of experiment demonstrate the effectiveness of this model. Wavelet transform and Rayleigh-Lamb equations are utilized to extract the features of crack AE sources. The results illustrate that the intensity ratio among AE modes can identify the AE source types and the AE sources with different frequencies in rail. There are uniform AE mode features existing in the AE signals from AE sources in rail web, however AE signals from AE sources in rail head and rail base have the complex and unstable AE modes. Different AE source types have the different propagation features in rail. It is helpful to understand the rail cracks and detect the rail cracks based on the AE technique.展开更多
An NUV-optical diagram composed from sources from the second Galaxy Evolution Explorer（GALEX） Ultraviolet Variability（GUVV-2） Catalog provides us with a method to tentatively classify the unknown GUVV-2 sources by...An NUV-optical diagram composed from sources from the second Galaxy Evolution Explorer（GALEX） Ultraviolet Variability（GUVV-2） Catalog provides us with a method to tentatively classify the unknown GUVV-2 sources by their NUV-optical magnitudes.For the purpose of testing the correctness and generality of the method,we carry out a program on the spectroscopic observations of the unidentified GUVV-2 sources.The spectroscopic identification of these 37 sources are 19 type-A to-F stars,10 type-G to-K stars and 7 M dwarf stars together with an AGN.We also present the light curves in the R-band for two RR Lyrae star candidates selected from the NUV-optical diagram,both of which undergo cyclic variations.Combining their light curves and colors,we classify them as RR Lyrae stars.To confirm the re-sults,we show a color-color diagram for the 37 newly identified spectroscopic objects compared with previously identified ones,which are consistent with our previous re-sults,indicating that the ultraviolet variable sources can initially be classified by their NUV/optical color-color diagram.展开更多
In order to comply with the trend of global climate change,countries are gradually promoting energy conservation and emission reduction,and prefabricated buildings have become one of the main paths for the constructio...In order to comply with the trend of global climate change,countries are gradually promoting energy conservation and emission reduction,and prefabricated buildings have become one of the main paths for the construction industry to develop towards carbon peaking and carbon neutrality goals.This paper takes the box-shaped column flange connection achieved by plug welding-core sleeve in the dormitory building of Tongzhou Campus of the Affiliated High School of Capital Normal University in China as the research object.Based on the consumption quota of prefabricated construction projects and the actual project quantity,the carbon emissions of steel structure column connection joints at different phases are calculated by the emission factor method,and it is proposed that the production consumption of building materials plays a key role in energy conservation and emission reduction.This paper concludes that the box-shaped column flange connection achieved by plug welding-core sleeve in the construction phase of an assembled steel building emits 49.5%less carbon dioxide than a conventional full fusion-welded joint.And the reason for the high carbon emissions of the latter is mainly from the amount of materials and machinery required for full penetration welding.It further affirms the green and environmental protection effect of the assembled steel structure plug welding-core sleeve flange connection joint in actual projects,and provides a reference for related research.展开更多
文摘Flame temperature distribution is one of the most important characteristic parameters in combustion research. The emission method is a good way to measure the luminous flame temperature field. The maximum entropy method is introduced to the temperature distribution measurement of a luminous flame using the emission method. A simplified mathematical model was derived by combining the thermal radiation theory, reconstruction algorithm and maximum entropy method. Suitable parameters were selected in the computing process. Good experimental results were obtained with pulverized coal flames.[
基金The China Ocean Mineral Resources Research and Development Association Research Program of the State Oceanic Administration of China under contract No.DY125-13-R-07the National Natural Science Foundation of China under contract Nos 41322036 and 41230960+1 种基金the Shandong Provincial Natural Science Foundation of China under contract No.ZR2014DP009the Special Basic Research Funds for Central Public Research Institutes for The First Institute of Oceanography,State Oceanic Administration of China under contract Nos GY0213G06 and GY02-2012G35
文摘An improved analytical method to determine the content of 52 major, minor and trace elements in marine geological samples, using a HF-HCl-HNO_3 acid system with a high-pressure closed digestion method（HPCD）, is studied by an inductively coupled plasma optical emission spectrometry（ICP-OES） and an inductively coupled plasma mass spectrometry（ICP-MS）. The operating parameters of the instruments are optimized, and the optimal analytical parameters are determined. The influences of optical spectrum and mass spectrum interferences, digestion methods and acid systems on the analytical results are investigated. The optimal spectral lines and isotopes are chosen, and internal standard element of rhodium is selected to compensate for matrix effects and analytical signals drifting. Compared with the methods of an electric heating plate digestion and a microwave digestion, a high-pressure closed digestion method is optimized with less acid, complete digestion,less damage for digestion process. The marine geological samples are dissolved completely by a HF-HCl-HNO_3 system, the relative error（RE） for the analytical results are all less than 6.0%. The method detection limits are 2–40μg/g by the ICP-OES, and 6–80 ng/g by ICP-MS. The methods are used to determine the marine sediment reference materials（GBW07309, GBW07311, GBW07313）, rock reference materials（GBW07103, GBW07104,GBW07105）, and cobalt-rich crust reference materials（GBW07337, GBW07338, GBW07339）, the obtained analytical results are in agreement with the certified values, and both of the relative standard deviation（RSD） and the relative error（RE） are less than 6.0%. The analytical method meets the requirements for determining 52 elements contents of bulk marine geological samples.
文摘The purpose of the work is to identify the acoustic emission （AE） signal in the melt and from the interphase during the crystal growth and to establish the connection between issue parameters： the number of signal events of frequency and the signal power with the growth conditions of temperature gradient and crystallization rate. Experiments on single crystal growth were carried out using hardware and software system which allows to perform spectral Fourier analysis of AE signals and to simultaneously remove the cooling curve for the entire period of crystallization. On the basis of spectral analysis of AE signals, a theoretical model of clusters in the aluminum melt was designed. The experimental results indicate an uneven abrupt advancement of the interface according to the configuration of each individual cluster.
基金supported by National Natural Science Foundation of China(Nos.11475040,11375041)the Fundamental Research Funds for the Central Universities(No.DUT14ZD[G]04)
文摘In this paper,nitrogen dielectric barrier discharge（DBD） plasma was generated in a quartz tube with coaxial wire-cylinder electrodes at atmospheric pressure.By varying the nitrogen gas flow（FN） in the range of 0-1 m3/h,the plasma optical emission spectra（OES） were measured and studied.The vibration（T_（vib）） and rotation temperature（T_（rot）） of nitrogen were obtained,by fitting the rovibronic bands of N_2（C^3∏_u-B^3∏_g,0-1）,and by the Boltzmann plot method for purposes of comparison.T_（vib） increased up to 2481 K with increasing nitrogen flow till0.2 m3/h,and then decreased with further increasing FN,while Trot decreased monotonously and approached to-350 K for FN ≥ 0.6 m^3/h.The intensity of N_2（C^3∏_u-B^3∏_g,0-0,1-0,0-3） and N_2~＋（B^2∑_u~＋-X^2Σ_g~＋,0-0） exhibited similar evolution with increasing FN to those of the T_（vib） and Trot,respectively.The discharge photos revealed that the discharge filaments gradually decreased with increasing FN,and eventually disappeared,which implied that a discharge mode transition emerged with increasing FN.The possible mechanism for the discharge mode transition is studied in detail according to the vibration（T_（vib）） and rotation temperature（T_（rot）） of nitrogen.
基金Supported by the National Natural Science Foundation of China
文摘The Large Sky Area Multi-Object Fiber Spectroscopic Telescope （LAMOST） has released more than two million spectra, which provide the opportunity to search for double-peaked narrow emission line （NEL） galaxies and active galactic nuclei （AGNs）. The double-peaked narrow-line profiles can be well modeled by two velocity components, respectively blueshifted and redshifted with respect to the sys- temic recession velocity. This paper presents 20 double-peaked NEL galaxies and AGNs found from LAMOST DR1 using a search method based on a multi-Gaussian fit of the narrow emission lines. Among them, ten have already been published by other authors, either listed as genuine double-peaked NEL objects or as asymmetric NEL objects, and the remaining ten are original discoveries. We discuss some pos- sible origins for the double-peaked narrow-line features, such as interaction between jet and narrow line regions, interaction with companion galaxies, and black hole bina- ries. Spatially resolved optical imaging and/or follow-up observations in other spectral bands are needed to further discuss the physical mechanisms at work.
文摘The extended “STIRPAT” model and the GM(1,1) model are used to predict the factors influencing inter-provincial carbon emission intensity and carbon intensity in China respectively. In this paper, based on the collation of inter-provincial carbon emission data, the extended “STIRPAT” model is formulated for carbon dioxide emissions and carbon intensity emissions, and the Hausman test is used to determine the influence form of the models. The main influencing factors of carbon intensity were identified: economic development level, energy intensity, and energy consumption structure. The paper constructs GM(1,1) model for carbon emission intensity from 2010-2019 using the gray prediction method,and calculates the carbon emission intensity of China’s inter-provincial 2022 by residual test, correlation test, variance, and small error probability test, and then predicts the carbon demand of each province and city in 2022 according to the expected average annual growth rate, and finally concludes that using carbon emission intensity as the carbon emission reduction target of each region, and it cannot fundamentally solve the problem of carbon pollution in China. Compared to the regional carbon emission reduction target, there is a greater degree of regional imbalance in carbon intensity between provinces in China, and the target of reducing carbon emission intensity somehow avoids the fact that the carbon emission reduction intensity target can be achieved without reducing the absolute amount of carbon emissions that continue to increase. The focus of achieving the “double carbon” target lies in the reduction of total carbon emissions, and the target of reducing carbon intensity will eventually be transformed into a binding target of total carbon emissions in the process of implementation, so attention should be shifted from recessiontype carbon reduction and efficiency-type carbon reduction to innovative carbon reduction. It is necessary to increase investment in renewable energy, and gradually expand the scope of application of photovoltaic, and wind power to ensure the reduction of total carbon emissions.
基金supported by the National Natural Science Foundation of China(No.42105094).
文摘Developing an anthropogenic carbon dioxides(CO_(2))emissions monitoring and verification support(MVS)capacity is essential to support the Global Stocktake(GST)and ratchet up Nationally Determined Contributions(NDCs).The 2019 IPCC refinement proposes top-down inversed CO_(2)emissions,primarily from fossil fuel(FFCO_(2)),as a viable emission dataset.Despite substantial progress in directly inferring FFCO_(2)emissions from CO_(2)observations,substantial challenges remain,particularly in distinguishing local CO_(2)enhancements from the high background due to the long atmospheric lifetime.Alternatively,using short-lived and co-emitted nitrogen dioxide(NO_(2))as a proxy in FFCO_(2)emission inversion has gained prominence.This methodology is broadly categorized into plume-based and emission ratios(ERs)-based inversion methods.In the plume-based methods,NO_(2)observations act as locators,constraints,and validators for deciphering CO_(2)plumes downwind of sources,typically at point source and city scales.The ERs-based inversion approach typically consists of two steps:inferring NO_(2)-based nitrogen oxides(NO_(x))emissions and converting NO_(x)to CO_(2)emissions using CO_(2)-to-NO_(x)ERs.While integrating NO_(2)observations into FFCO_(2)emission inversion offers advantages over the direct CO_(2)-based methods,uncertainties persist,including both structural and data-related uncertainties.Addressing these uncertainties is a primary focus for future research,which includes deploying nextgeneration satellites and developing advanced inversion systems.Besides,data caveats are necessary when releasing data to users to prevent potential misuse.Advancing NO_(2)-based CO_(2)emission inversion requires interdisciplinary collaboration across multiple communities of remote sensing,emission inventory,transport model improvement,and atmospheric inversion algorithm development.
基金supported by China National Key Basic Research Science Foundation Project(G1999043400)the Hundred Talents Program(Global Environmental Change)by the Chinese Academy of Sciences+1 种基金the National Natural Science Foundation of China(No.40205017)Social Commonweal Research Project(2002DIA20012)by the Ministry of Science and Technology of China.
文摘Dust events occurred frequently in Beijing in recent years. In this work, 120 aerosol samples were collected in two typical dust events (21-22 March and 15 May) and a non-dust period in Beijing from March to May 2001. Samples were analyzed for major elemental components by the Proton Induced X-ray Emission (PIXE) method. Results show that the enrichment factors of crustal elements such as Mg, Al, and Ti had little differences between the dust period and the non-dust period in Beijing, while the enrichment factors of other elements that have a relation to anthropogenic emissions were very low during the dust period. The results derived by using multivariate factor analysis from the observation data show that the sources such as soil dust, industry, and fuel combustion were among the major contributors to the particles in Beijing.
基金the National Natural Science Foundation of China （Grant No. 40305020）.
文摘The total emission control method based on atmospheric environmental capacity is the most effective in air pollution mitigation. The atmospheric environmental capacities of SO2 on representative days over Lanzhou are estimated using the numerical models RAMS, HYPACT and a linear programming model, according to the national ambient air quality standard of China （NAAQSCHN）. The results show that the fields of meteorological elements and SO2 simulated by the models agree reasonably well with observations. The atmospheric environmental capacity of SO2 over Lanzhou is around 111.7 × 10^3 kg d^-1, and in order to meet the air quality level Ⅱ of the NAAQSCHN, SO2 emissions need to be reduced by 20%.
基金supported by the China Scholarship Council,the National Natural Science Foundation of China(61171197,61201307,61371045)the Innovation Funds of Harbin Institute of Technology(Grant IDGA18102011)the Promotive Research Fund for Excellent Young and Middle-Aged Scientisits of Shandong Province(BS2010DX001)
文摘The safety of rail is very important for the development of high speed railway, and it is necessary to investigate the features of inner cracks in rail. In order to obtain the features of Acoustic Emission （AE） sources of inner cracks in rail, AE sources with different types, depths and propagation distances are examined for crack in rail. The finite element method is utilized to model the rail with cracks and the results of experiment demonstrate the effectiveness of this model. Wavelet transform and Rayleigh-Lamb equations are utilized to extract the features of crack AE sources. The results illustrate that the intensity ratio among AE modes can identify the AE source types and the AE sources with different frequencies in rail. There are uniform AE mode features existing in the AE signals from AE sources in rail web, however AE signals from AE sources in rail head and rail base have the complex and unstable AE modes. Different AE source types have the different propagation features in rail. It is helpful to understand the rail cracks and detect the rail cracks based on the AE technique.
基金Supported by the National Natural Science Foundation of China(Grant No.10803008)supported by the National Basic Research Program of China (Grant 2009CB824800)supported by the Open Project Program of the Key Laboratory of Optical Astronomy,NAOC,CAS
文摘An NUV-optical diagram composed from sources from the second Galaxy Evolution Explorer（GALEX） Ultraviolet Variability（GUVV-2） Catalog provides us with a method to tentatively classify the unknown GUVV-2 sources by their NUV-optical magnitudes.For the purpose of testing the correctness and generality of the method,we carry out a program on the spectroscopic observations of the unidentified GUVV-2 sources.The spectroscopic identification of these 37 sources are 19 type-A to-F stars,10 type-G to-K stars and 7 M dwarf stars together with an AGN.We also present the light curves in the R-band for two RR Lyrae star candidates selected from the NUV-optical diagram,both of which undergo cyclic variations.Combining their light curves and colors,we classify them as RR Lyrae stars.To confirm the re-sults,we show a color-color diagram for the 37 newly identified spectroscopic objects compared with previously identified ones,which are consistent with our previous re-sults,indicating that the ultraviolet variable sources can initially be classified by their NUV/optical color-color diagram.
基金funded by National Natural Science Foundation of China,grant number 51778036Joint Program of Beijing Natural Science Foundation and Education Commission,grant number KZ201910016018.
文摘In order to comply with the trend of global climate change,countries are gradually promoting energy conservation and emission reduction,and prefabricated buildings have become one of the main paths for the construction industry to develop towards carbon peaking and carbon neutrality goals.This paper takes the box-shaped column flange connection achieved by plug welding-core sleeve in the dormitory building of Tongzhou Campus of the Affiliated High School of Capital Normal University in China as the research object.Based on the consumption quota of prefabricated construction projects and the actual project quantity,the carbon emissions of steel structure column connection joints at different phases are calculated by the emission factor method,and it is proposed that the production consumption of building materials plays a key role in energy conservation and emission reduction.This paper concludes that the box-shaped column flange connection achieved by plug welding-core sleeve in the construction phase of an assembled steel building emits 49.5%less carbon dioxide than a conventional full fusion-welded joint.And the reason for the high carbon emissions of the latter is mainly from the amount of materials and machinery required for full penetration welding.It further affirms the green and environmental protection effect of the assembled steel structure plug welding-core sleeve flange connection joint in actual projects,and provides a reference for related research.
