We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-im...We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-imate Riemann solver,we identify its dissipative terms,and in these terms,we use slope-limited linear reconstruction.All gradients needed for our method are calculated with linearly reproducing kernels that are constructed to enforce the two lowest-order consistency relations.We scrutinize our reproducing kernel implementation carefully on a“glass-like”particle distribution,and we find that constant and linear functions are recovered to machine precision.We probe our method in a series of challenging 3D benchmark problems ranging from shocks over instabilities to Schulz-Rinne-type vorticity-creating shocks.All of our simulations show excellent agreement with analytic/reference solutions.展开更多
Cloud radiative kernels were built by BCC_RAD(Beijing Climate Center radiative transfer model)radiative transfer code.Then,short-term cloud feedback and its mechanisms in East Asia(0.5°S−60.5°N,69.5°−15...Cloud radiative kernels were built by BCC_RAD(Beijing Climate Center radiative transfer model)radiative transfer code.Then,short-term cloud feedback and its mechanisms in East Asia(0.5°S−60.5°N,69.5°−150.5°E)were analyzed quantitatively using the kernels combined with MODIS satellite data from July 2002 to June 2018.According to the surface and monsoon types,four subregions in East Asia-the Tibetan Plateau,northwest,temperate monsoon(TM),and subtropical monsoon(SM)—were selected.The average longwave,shortwave,and net cloud feedbacks in East Asia are−0.68±1.20,1.34±1.08,and 0.66±0.40 W m^−2 K^−1(±2σ),respectively,among which the net feedback is dominated by the positive shortwave feedback.Positive feedback in SM is the strongest of all subregions,mainly due to the contributions of nimbostratus and stratus.In East Asia,short-term feedback in spring is primarily caused by marine stratus in SM,in summer is primarily driven by deep convective cloud in TM,in autumn is mainly caused by land nimbostratus in SM,and in winter is mainly driven by land stratus in SM.Cloud feedback in East Asia is chiefly driven by decreases in mid-level and low cloud fraction owing to the changes in relative humidity,and a decrease in low cloud optical thickness due to the changes in cloud water content.展开更多
In this work, we developed a method to efficiently optimize the kernel function for combined data of various different sources with their corresponding kernels being already available. The vectorization of the combine...In this work, we developed a method to efficiently optimize the kernel function for combined data of various different sources with their corresponding kernels being already available. The vectorization of the combined data is achieved by a weighted concatenation of the existing data vectors. This induces a kernel matrix composed of the existing kernels as blocks along the main diagonal, weighted according to the corresponding the subspaces span by the data. The induced block kernel matrix is optimized in the platform of least-squares support vector machines simultaneously as the LS-SVM is being trained, by solving an extended set of linear equations, other than a quadratically constrained quadratic programming as in a previous method. The method is tested on a benchmark dataset, and the performance is significantly improved from the highest ROC score 0.84 using individual data source to ROC score 0.92 with data fusion.展开更多
In order to study the correlation between the cracking of rice (Oryza sativa L.) kernels and the molecular structure of the amylopectin in them, we attempted optical sum frequency generation (SFG) spectroscopy in the ...In order to study the correlation between the cracking of rice (Oryza sativa L.) kernels and the molecular structure of the amylopectin in them, we attempted optical sum frequency generation (SFG) spectroscopy in the C-H stretching vibration region for normal and cracked japonica non-glutinous rice kernels. The samples were Koshihikari and Nipponbare. In Nipponbare, the width of the SFG spectrum peak at 2915 cm<sup>- 1</sup> of the cracked rice kernels was broader than that of the normal ones, while for Koshihikari there was no clear difference. The width of the 2915 cm<sup>- 1</sup> peak is suggested to originate from the variety of the higher-order structure of the saccharide chains in amylopectin. Although this is a tentative result, this method is shown to have a potential of serving for preventing the cracking of the rice kernels.展开更多
基金supported by the Swedish Research Council(VR)under grant number 2020-05044by the research environment grant"Gravitational Radiation and Electromagnetic Astrophysical Transients"(GREAT)funded by the Swedish Research Council(VR)under Dnr 2016-06012+2 种基金by the Knut and Alice Wallenberg Foundation under grant Dnr.KAW 2019.0112by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany's Excellence Strategy-EXC 2121"Quantum Universe"-390833306by the European Research Council(ERC)Advanced Grant INSPIRATION under the European Union's Horizon 2020 Research and Innovation Programme(Grant agreement No.101053985).
文摘We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-imate Riemann solver,we identify its dissipative terms,and in these terms,we use slope-limited linear reconstruction.All gradients needed for our method are calculated with linearly reproducing kernels that are constructed to enforce the two lowest-order consistency relations.We scrutinize our reproducing kernel implementation carefully on a“glass-like”particle distribution,and we find that constant and linear functions are recovered to machine precision.We probe our method in a series of challenging 3D benchmark problems ranging from shocks over instabilities to Schulz-Rinne-type vorticity-creating shocks.All of our simulations show excellent agreement with analytic/reference solutions.
基金supported by the National Key R&D Program of China(Grant No.2017YFA0603502)the National Natural Science Foundation of China(Grant Nos.91644211 and 41575002).
文摘Cloud radiative kernels were built by BCC_RAD(Beijing Climate Center radiative transfer model)radiative transfer code.Then,short-term cloud feedback and its mechanisms in East Asia(0.5°S−60.5°N,69.5°−150.5°E)were analyzed quantitatively using the kernels combined with MODIS satellite data from July 2002 to June 2018.According to the surface and monsoon types,four subregions in East Asia-the Tibetan Plateau,northwest,temperate monsoon(TM),and subtropical monsoon(SM)—were selected.The average longwave,shortwave,and net cloud feedbacks in East Asia are−0.68±1.20,1.34±1.08,and 0.66±0.40 W m^−2 K^−1(±2σ),respectively,among which the net feedback is dominated by the positive shortwave feedback.Positive feedback in SM is the strongest of all subregions,mainly due to the contributions of nimbostratus and stratus.In East Asia,short-term feedback in spring is primarily caused by marine stratus in SM,in summer is primarily driven by deep convective cloud in TM,in autumn is mainly caused by land nimbostratus in SM,and in winter is mainly driven by land stratus in SM.Cloud feedback in East Asia is chiefly driven by decreases in mid-level and low cloud fraction owing to the changes in relative humidity,and a decrease in low cloud optical thickness due to the changes in cloud water content.
文摘In this work, we developed a method to efficiently optimize the kernel function for combined data of various different sources with their corresponding kernels being already available. The vectorization of the combined data is achieved by a weighted concatenation of the existing data vectors. This induces a kernel matrix composed of the existing kernels as blocks along the main diagonal, weighted according to the corresponding the subspaces span by the data. The induced block kernel matrix is optimized in the platform of least-squares support vector machines simultaneously as the LS-SVM is being trained, by solving an extended set of linear equations, other than a quadratically constrained quadratic programming as in a previous method. The method is tested on a benchmark dataset, and the performance is significantly improved from the highest ROC score 0.84 using individual data source to ROC score 0.92 with data fusion.
文摘In order to study the correlation between the cracking of rice (Oryza sativa L.) kernels and the molecular structure of the amylopectin in them, we attempted optical sum frequency generation (SFG) spectroscopy in the C-H stretching vibration region for normal and cracked japonica non-glutinous rice kernels. The samples were Koshihikari and Nipponbare. In Nipponbare, the width of the SFG spectrum peak at 2915 cm<sup>- 1</sup> of the cracked rice kernels was broader than that of the normal ones, while for Koshihikari there was no clear difference. The width of the 2915 cm<sup>- 1</sup> peak is suggested to originate from the variety of the higher-order structure of the saccharide chains in amylopectin. Although this is a tentative result, this method is shown to have a potential of serving for preventing the cracking of the rice kernels.
