Previous studies suggest that dipolarization fronts (DFs) are 1 to 3RE (RE is the earth radius) wide in the dawn-dusk direction. Recent kinetic simulations have found that DFs may break up into small-scale structures ...Previous studies suggest that dipolarization fronts (DFs) are 1 to 3RE (RE is the earth radius) wide in the dawn-dusk direction. Recent kinetic simulations have found that DFs may break up into small-scale structures after they are produced by reconnection. Motivated by this simulation, we revisited the scale size of DFs in the dawn-dusk direction by using Cluster observations during the years when the inter-distance among Cluster spacecraft was between 1000 and 2000 km. We selected the DFs that were detected by more than one spacecraft and estimated the radii of these DFs by a simple geometrical analysis, which is based on comparison of DF normals observed by different spacecraft. We found a few DFs that were only a few ion inertial lengths in the dawn-dusk direction. These results point out the importance of multi-scale coupling during the evolution of DFs.展开更多
The time evolution of the magnetic field aligned super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma, is studied with the help of the model simulation...The time evolution of the magnetic field aligned super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma, is studied with the help of the model simulation. A new version of the two-dimensional mathematical model, developed earlier in the Polar Geophysical Institute, is utilized to investigate the temporal history of the irregularity with circular cross section, created initially in the near-Earth plasma. The utilized model is based on a numerical solution of the Vlasov-Poisson system of equations, with the Vlasov equations describing the distribution functions of charged particles and the Poisson equation governing the self-consistent electric field. The results of simulation indicate that the mobility of the positive ions ought to influence essentially on the time evolution of the super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma.展开更多
Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carb...Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carbon and forest aboveground biomass(FAGB).Different levels of detail are needed to estimate FAGB at local,regional and national scales.Multi-scale remote sensing analysis from high,medium and coarse spatial resolution data,along with field sampling,is one approach often used.However,the methods developed are still time consuming,expensive,and inconvenient for systematic monitoring,especially for developing countries,as they require vast numbers of field samples for upscaling.Here,we recommend a convenient two-scale approach to estimate FAGB that was tested in our study sites.The study was conducted in the Chitwan district of Nepal using GeoEye-1(0.5 m),Landsat(30 m)and Google Earth very high resolution(GEVHR)Quickbird(0.65 m)images.For the local scale(Kayerkhola watershed),tree crowns of the area were delineated by the object-based image analysis technique on GeoEye images.An overall accuracy of 83%was obtained in the delineation of tree canopy cover(TCC)per plot.A TCC vs.FAGB model was developed based on the TCC estimations from GeoEye and FAGB measurements from field sample plots.A coefficient of determination(R2)of 0.76 was obtained in the modelling,and a value of 0.83 was obtained in the validation of the model.To upscale FAGB to the entire district,open source GEVHR images were used as virtual field plots.We delineated their TCC values and then calculated FAGB based on a TCC versus FAGB model.Using the multivariate adaptive regression splines machine learning algorithm,we developed a model from the relationship between the FAGB of GEVHR virtual plots with predictor parameters from Landsat 8 bands and vegetation indices.The model was then used to extrapolate FAGB to the entire district.This approach considerably reduced the need for field data and commercial very high resolution imagery while achieving two-scale forest information and FAGB estimates at high resolution(30 m)and accuracy(R2=0.76 and 0.7)with minimal error(RMSE=64 and 38 tons ha-1)at local and regional scales.This methodology is a promising technique for cost-effective FAGB and carbon estimations and can be replicated with limited resources and time.The method is especially applicable for developing countries that have low budgets for carbon estimations,and it is also applicable to the Reducing Emissions from Deforestation and Forest Degradation(REDD?)monitoring reporting and verification processes.展开更多
The oxidation resistance of 5Cr21Mn9Ni4N steel micro-alloying by RE at 700 - 900 ℃ was investigated. The results indicate that oxidation exponent n and oxidation activation energy are increased, and oxidation velocit...The oxidation resistance of 5Cr21Mn9Ni4N steel micro-alloying by RE at 700 - 900 ℃ was investigated. The results indicate that oxidation exponent n and oxidation activation energy are increased, and oxidation velocity constant kp is decreased when 0.2% RE is added in 5Cr21Mn9Ni4N steel. The addition of RE elements does not alter phase constitution of oxidation scale, however it improves the configuration of oxidation scale, and increases thermal stability and adhesivity of oxidation scale, which results in the raise of oxidation resistance of 5Cr21Mn9Ni4N steel at high temperature. The oxidation scale constitutes of refractory steel transfer from manganic oxide mostly to ferric oxide mostly with the increase of temperature, which leads to descend of compactness and desquamation resistance of oxidation scale. The mass increase of ferric oxide in the oxidation scale and the looseness of oxidation scale are the main reason to descend the oxidation resistance of refractory steel.展开更多
The cyclic oxidation experiments on cast high speed steel roll added rare earth elements were using thermal gravimetric analyser. The structure morphology observation, phase analysis, chemical component analysis and c...The cyclic oxidation experiments on cast high speed steel roll added rare earth elements were using thermal gravimetric analyser. The structure morphology observation, phase analysis, chemical component analysis and cast on oxide films after cyclic oxidation carried out, adopting SEM, XRD, EDS, respectively. The results show that the cyclic oxidation possesses a characteristic, i.e. oxidized selectively on matrix and carbide, formed oxide film M_2O_3 which contain different alloying elements on matrix and carbide, the oxides formed on the carbides are higher. Oxide grain size growing with cyclic oxidation temperature increasing, the oxidation kinetic curve conforms to the parabola law. Rare earth elements can increase cyclic oxidation resistance of high speed steel, porosity of high speed steel oxide films is lower than non-added rare earth element steel, oxidation occurs selectively on carbide particles of rare earth elements which contains Ce, La, etc., formed similar “nail” granular oxide-which fixes oxide film to matrix, and strengthens adherence of oxide film that is not easy to drop-out. This is one of the systems to increase oxide film adherence.展开更多
A copper-zinc alloy doped with rare earth elements was prepared and the mechanism was demonstrated in a simulating boiler and circulating cooling water with rigidity 1 mmol·L-1. The polar curve and scale inhibiti...A copper-zinc alloy doped with rare earth elements was prepared and the mechanism was demonstrated in a simulating boiler and circulating cooling water with rigidity 1 mmol·L-1. The polar curve and scale inhibiting ability of the alloy was tested by a corrosion measurement system and a scale inhibition evaluation system, respectively. Scale samples were characterized with SEM and XRD. It is found that the transfer of cations could be promoted by doping with proper rare earth elements, and the corrosion potentials descend by 25～126 mV. The results indicated that the copper-zinc alloy doped with rare earth elements has higher scale inhibiting ability of CaCO3. The growth of calcite was affected by zinc ions dissolved because of primary battery reaction, and the transition of calcium carbonate from aragonite to calcite was hampered resulting in the proportion of aragonite to calcite is changed from 1.7∶1 to 2.7∶1.展开更多
This paper discovers the secret codes of the scale distribution from Planck scale to the Sun-scale by using Planck length derived from three fundamental physics constants, i.e., gravitation constant G, light speed c a...This paper discovers the secret codes of the scale distribution from Planck scale to the Sun-scale by using Planck length derived from three fundamental physics constants, i.e., gravitation constant G, light speed c and Plank constant, and starting from the global consideration of treating the whole universe as a well unified entity in all scales. According to this symmetric scale distribution law of different scale regions: (a) we naturally give a possibility overcoming the difficulty of the desert effect between the grand unification scale and electroweak unification scale relevant to quarks and leptons, and it is really surprising to discover that the scales of quarks & electrons, protons & neutrons and atoms again all sequentially locate at the predicted points of the scale space;(b) we closely uncover the scale of the cells, which is the basic unit constructing the human bodies;(c) even the average height of human being is naturally deduced;(d) further, it is very surprising that the scales of the celestial bodies tightly related to us human beings, including the earth and the sun, also exactly fall at the predicted points in scale space in order. Therefore, all these scales with 105n cm order (n = 0, 1, 2, …, 9) above just give a proof of very key anthropic principle for whole mankind (which just makes the anthropic principle be reduced as anthropic theorem), i.e., matter stratums (a) and (b) are inorganic and organic bases of constructing human being respectively;matter stratum (c) is just human being;matter stratums (d) are the living environments of human being. Namely, everything is for or relevant to the existence of human being. Consequently, the experimentally checked scale ladder of well-known matter levels just coincides with the scale ladder predicted by the deduced distribution law. From Planck scale to the Sun scale, people may systematically build up the exact scientific theories corresponding ten matter stratums, may set up the different sciences among the different cross stratums, further, can systematically understand all the different sciences and their relations in the deepest way up to now.展开更多
基金supported by the National Natural Science Foundation of China (NSFC) under grant 41774154 and 41504123the Science Foundation of Jiangxi Province under grant 20122BAB21 2002+1 种基金the Nanchang University graduate innovation special fund project under grant CX2017106the Key Industry Innovation Chain of Shaanxi under grant 2018JQ4032
文摘Previous studies suggest that dipolarization fronts (DFs) are 1 to 3RE (RE is the earth radius) wide in the dawn-dusk direction. Recent kinetic simulations have found that DFs may break up into small-scale structures after they are produced by reconnection. Motivated by this simulation, we revisited the scale size of DFs in the dawn-dusk direction by using Cluster observations during the years when the inter-distance among Cluster spacecraft was between 1000 and 2000 km. We selected the DFs that were detected by more than one spacecraft and estimated the radii of these DFs by a simple geometrical analysis, which is based on comparison of DF normals observed by different spacecraft. We found a few DFs that were only a few ion inertial lengths in the dawn-dusk direction. These results point out the importance of multi-scale coupling during the evolution of DFs.
文摘The time evolution of the magnetic field aligned super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma, is studied with the help of the model simulation. A new version of the two-dimensional mathematical model, developed earlier in the Polar Geophysical Institute, is utilized to investigate the temporal history of the irregularity with circular cross section, created initially in the near-Earth plasma. The utilized model is based on a numerical solution of the Vlasov-Poisson system of equations, with the Vlasov equations describing the distribution functions of charged particles and the Poisson equation governing the self-consistent electric field. The results of simulation indicate that the mobility of the positive ions ought to influence essentially on the time evolution of the super-small-scale irregularities in the concentration of charged particles, existing in the near-Earth rarefied plasma.
基金supported by the CAS Strategic Priority Research Program(No.XDA19030402)the National Key Research and Development Program of China(No.2016YFD0300101)+2 种基金the Natural Science Foundation of China(Nos.31571565,31671585)the Key Basic Research Project of the Shandong Natural Science Foundation of China(No.ZR2017ZB0422)Research Funding of Qingdao University(No.41117010153)
文摘Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carbon and forest aboveground biomass(FAGB).Different levels of detail are needed to estimate FAGB at local,regional and national scales.Multi-scale remote sensing analysis from high,medium and coarse spatial resolution data,along with field sampling,is one approach often used.However,the methods developed are still time consuming,expensive,and inconvenient for systematic monitoring,especially for developing countries,as they require vast numbers of field samples for upscaling.Here,we recommend a convenient two-scale approach to estimate FAGB that was tested in our study sites.The study was conducted in the Chitwan district of Nepal using GeoEye-1(0.5 m),Landsat(30 m)and Google Earth very high resolution(GEVHR)Quickbird(0.65 m)images.For the local scale(Kayerkhola watershed),tree crowns of the area were delineated by the object-based image analysis technique on GeoEye images.An overall accuracy of 83%was obtained in the delineation of tree canopy cover(TCC)per plot.A TCC vs.FAGB model was developed based on the TCC estimations from GeoEye and FAGB measurements from field sample plots.A coefficient of determination(R2)of 0.76 was obtained in the modelling,and a value of 0.83 was obtained in the validation of the model.To upscale FAGB to the entire district,open source GEVHR images were used as virtual field plots.We delineated their TCC values and then calculated FAGB based on a TCC versus FAGB model.Using the multivariate adaptive regression splines machine learning algorithm,we developed a model from the relationship between the FAGB of GEVHR virtual plots with predictor parameters from Landsat 8 bands and vegetation indices.The model was then used to extrapolate FAGB to the entire district.This approach considerably reduced the need for field data and commercial very high resolution imagery while achieving two-scale forest information and FAGB estimates at high resolution(30 m)and accuracy(R2=0.76 and 0.7)with minimal error(RMSE=64 and 38 tons ha-1)at local and regional scales.This methodology is a promising technique for cost-effective FAGB and carbon estimations and can be replicated with limited resources and time.The method is especially applicable for developing countries that have low budgets for carbon estimations,and it is also applicable to the Reducing Emissions from Deforestation and Forest Degradation(REDD?)monitoring reporting and verification processes.
文摘The oxidation resistance of 5Cr21Mn9Ni4N steel micro-alloying by RE at 700 - 900 ℃ was investigated. The results indicate that oxidation exponent n and oxidation activation energy are increased, and oxidation velocity constant kp is decreased when 0.2% RE is added in 5Cr21Mn9Ni4N steel. The addition of RE elements does not alter phase constitution of oxidation scale, however it improves the configuration of oxidation scale, and increases thermal stability and adhesivity of oxidation scale, which results in the raise of oxidation resistance of 5Cr21Mn9Ni4N steel at high temperature. The oxidation scale constitutes of refractory steel transfer from manganic oxide mostly to ferric oxide mostly with the increase of temperature, which leads to descend of compactness and desquamation resistance of oxidation scale. The mass increase of ferric oxide in the oxidation scale and the looseness of oxidation scale are the main reason to descend the oxidation resistance of refractory steel.
文摘The cyclic oxidation experiments on cast high speed steel roll added rare earth elements were using thermal gravimetric analyser. The structure morphology observation, phase analysis, chemical component analysis and cast on oxide films after cyclic oxidation carried out, adopting SEM, XRD, EDS, respectively. The results show that the cyclic oxidation possesses a characteristic, i.e. oxidized selectively on matrix and carbide, formed oxide film M_2O_3 which contain different alloying elements on matrix and carbide, the oxides formed on the carbides are higher. Oxide grain size growing with cyclic oxidation temperature increasing, the oxidation kinetic curve conforms to the parabola law. Rare earth elements can increase cyclic oxidation resistance of high speed steel, porosity of high speed steel oxide films is lower than non-added rare earth element steel, oxidation occurs selectively on carbide particles of rare earth elements which contains Ce, La, etc., formed similar “nail” granular oxide-which fixes oxide film to matrix, and strengthens adherence of oxide film that is not easy to drop-out. This is one of the systems to increase oxide film adherence.
基金Key Technologies R&D Program of Tianjin (06YFGZGX02400)
文摘A copper-zinc alloy doped with rare earth elements was prepared and the mechanism was demonstrated in a simulating boiler and circulating cooling water with rigidity 1 mmol·L-1. The polar curve and scale inhibiting ability of the alloy was tested by a corrosion measurement system and a scale inhibition evaluation system, respectively. Scale samples were characterized with SEM and XRD. It is found that the transfer of cations could be promoted by doping with proper rare earth elements, and the corrosion potentials descend by 25～126 mV. The results indicated that the copper-zinc alloy doped with rare earth elements has higher scale inhibiting ability of CaCO3. The growth of calcite was affected by zinc ions dissolved because of primary battery reaction, and the transition of calcium carbonate from aragonite to calcite was hampered resulting in the proportion of aragonite to calcite is changed from 1.7∶1 to 2.7∶1.
文摘This paper discovers the secret codes of the scale distribution from Planck scale to the Sun-scale by using Planck length derived from three fundamental physics constants, i.e., gravitation constant G, light speed c and Plank constant, and starting from the global consideration of treating the whole universe as a well unified entity in all scales. According to this symmetric scale distribution law of different scale regions: (a) we naturally give a possibility overcoming the difficulty of the desert effect between the grand unification scale and electroweak unification scale relevant to quarks and leptons, and it is really surprising to discover that the scales of quarks & electrons, protons & neutrons and atoms again all sequentially locate at the predicted points of the scale space;(b) we closely uncover the scale of the cells, which is the basic unit constructing the human bodies;(c) even the average height of human being is naturally deduced;(d) further, it is very surprising that the scales of the celestial bodies tightly related to us human beings, including the earth and the sun, also exactly fall at the predicted points in scale space in order. Therefore, all these scales with 105n cm order (n = 0, 1, 2, …, 9) above just give a proof of very key anthropic principle for whole mankind (which just makes the anthropic principle be reduced as anthropic theorem), i.e., matter stratums (a) and (b) are inorganic and organic bases of constructing human being respectively;matter stratum (c) is just human being;matter stratums (d) are the living environments of human being. Namely, everything is for or relevant to the existence of human being. Consequently, the experimentally checked scale ladder of well-known matter levels just coincides with the scale ladder predicted by the deduced distribution law. From Planck scale to the Sun scale, people may systematically build up the exact scientific theories corresponding ten matter stratums, may set up the different sciences among the different cross stratums, further, can systematically understand all the different sciences and their relations in the deepest way up to now.
