We prepare a class of locally resonant （LR） sonic materials. The experiments demonstrate that the resonant frequency decreases with the increasing density of the scattering unit cores or with the reducing elastic co...We prepare a class of locally resonant （LR） sonic materials. The experiments demonstrate that the resonant frequency decreases with the increasing density of the scattering unit cores or with the reducing elastic constants of the silicone rubber coating. By combining three LR layers of different resonant frequencies and choosing 10 dB as the threshold of relative attenuation, we obtain an ultrawide bandgap （200-950Hz） sound material with an average transmission loss 22 dB lower than that dictated by mass density law.展开更多
A heavy rainfall event caused by a mesoscale convective system(MCS),which occurred over the Yellow River midstream area during 7-9 July 2016,was analyzed using observational,high-resolution satellite,NCEP/NCAR reanaly...A heavy rainfall event caused by a mesoscale convective system(MCS),which occurred over the Yellow River midstream area during 7-9 July 2016,was analyzed using observational,high-resolution satellite,NCEP/NCAR reanalysis,and numerical simulation data.This heavy rainfall event was caused by one mesoscale convective complex(MCC)and five MCSs successively.The MCC rainstorm occurred when southwesterly winds strengthened into a jet.The MCS rainstorms occurred when low-level wind fields weakened,but their easterly components in the lower and boundary layers increased continuously.Numerical analysis revealed that there were obvious differences between the MCC and MCS rainstorms,including their three-dimensional airflow structure,disturbances in wind fields and vapor distributions,and characteristics of energy conversion and propagation.Formation of the MCC was related to southerly conveyed water vapor and energy to the north,with obvious water vapor exchange between the free atmosphere and the boundary layer.Continuous regeneration and development of the MCSs mainly relied on maintenance of an upward extension of a positive water vapor disturbance.The MCC rainstorm was triggered by large range of convergent ascending motion caused by a southerly jet,and easterly disturbance within the boundary layer.While a southerly fluctuation and easterly disturbance in the boundary layer were important triggers of the MCS rainstorms.Maintenance and development of the MCC and MCSs were linked to secondary circulation,resulting from convergence of Ekman non-equilibrium flow in the boundary layer.Both intensity and motion of the convergence centers in MCC and MCS cases were different.Clearly,sub-synoptic scale systems in the middle troposphere played a leading role in determining precipitation distribution during this event.Although mesoscale systems triggered by the sub-synoptic scale system induced the heavy rainfall,small-scale disturbances within the boundary layer determined its intensity and location.展开更多
Quantum dynamics calculations for the title reaction H（2S） ＋ S2（X3∑g） → SH（X2П） ＋S（3P） are performed byusing a globally accurate double many-body expansion potential energy surface [J. Phys. Chem. A 115 5...Quantum dynamics calculations for the title reaction H（2S） ＋ S2（X3∑g） → SH（X2П） ＋S（3P） are performed byusing a globally accurate double many-body expansion potential energy surface [J. Phys. Chem. A 115 5274 （2011）]. The Chebyshev real wave packet propagation method is employed to obtain the dynamical information, such as reaction probability, initial state-specified integral cross section, and thermal rate constant. It is found not only that there is a reaction threshold near 0.7 eV in both reaction probabilities and integral cross section curves, but also that both the probability and cross section increase firstly and then decrease as the collision energy increases. The existence of the resonance structure in both the probability and cross section curves is ascribed to the deep potential well. The calculation of the rate constant reveals that the reaction occurring on the potential energy surface of the ground-state HS2 is slow to take place.展开更多
This paper proposes new heuristic distributed parallel algorithms for search-ing and planning, which are based on the concepts of wave concurrent prop-agations and competitive activation mechanisms. These algorithms a...This paper proposes new heuristic distributed parallel algorithms for search-ing and planning, which are based on the concepts of wave concurrent prop-agations and competitive activation mechanisms. These algorithms are char-acterized by simplicity and clearness of control strategies for searching, anddistinguished abilities in many aspects, such as high speed processing, widesuitability for searching AND/OR implicit graphs, and ease in hardware imple-mentation.展开更多
On the basis of studying wave package propagation, this paper investigated the relationship between high frequency wave package propagation and transient waves＇ evolvement or the subtropical high＇s latitudinal movem...On the basis of studying wave package propagation, this paper investigated the relationship between high frequency wave package propagation and transient waves＇ evolvement or the subtropical high＇s latitudinal movement. The results showed that during winter the lifetime of wave package was longer and usually persisted for 7-10 days with a propagating speed of 2-10 m s-l. Usually they propagated southeastward at the beginning, then turned to northeast. During summer the lifetime and intensity of wave package became shorter and weaker. It availed development （attenuation） of troughs when the strong wave package center was intensified （weakened） which overlapped with trough. If strong wave package center kept overlapping with ridge, the ridge would abate later in a few days. Obvious jumping northward （retreating southward） processes of Western Pacific subtropical high （WPSH） were （not） usually related to strong wave package centers located at South China Sea area （South Asia area and Temperate Zone） for 5 days or longer. After two seasonal jumping processes, there were persisting strong wave package centers for 5 days or longer. WPSH retreating processes were also related to activities of strong wave package centers over South Asian area and temperate area as well as the strong wave package centers of typhoon, and all these centers persisted for 5 days or longer.展开更多
According to a novel electronic ground-state potential energy surface of H2O^＋（X^4 A″）,we calculate the reaction probabilities and the integral cross section for the titled reaction O^＋＋ D2→OD^＋＋ D by the Che...According to a novel electronic ground-state potential energy surface of H2O^＋（X^4 A″）,we calculate the reaction probabilities and the integral cross section for the titled reaction O^＋＋ D2→OD^＋＋ D by the Chebyshev wave packet propagation method.The reaction probabilities in a collision-energy range of 0.0 e V–1.0 e V show an oscillatory structure for the O^＋＋ D2 reaction due to the existence of the potential well.Compared with the results of Martinez et al.,the present integral cross section is large,which is in line with experimental data.展开更多
文摘We prepare a class of locally resonant （LR） sonic materials. The experiments demonstrate that the resonant frequency decreases with the increasing density of the scattering unit cores or with the reducing elastic constants of the silicone rubber coating. By combining three LR layers of different resonant frequencies and choosing 10 dB as the threshold of relative attenuation, we obtain an ultrawide bandgap （200-950Hz） sound material with an average transmission loss 22 dB lower than that dictated by mass density law.
基金National Natural Science Foundation of China(41475050)
文摘A heavy rainfall event caused by a mesoscale convective system(MCS),which occurred over the Yellow River midstream area during 7-9 July 2016,was analyzed using observational,high-resolution satellite,NCEP/NCAR reanalysis,and numerical simulation data.This heavy rainfall event was caused by one mesoscale convective complex(MCC)and five MCSs successively.The MCC rainstorm occurred when southwesterly winds strengthened into a jet.The MCS rainstorms occurred when low-level wind fields weakened,but their easterly components in the lower and boundary layers increased continuously.Numerical analysis revealed that there were obvious differences between the MCC and MCS rainstorms,including their three-dimensional airflow structure,disturbances in wind fields and vapor distributions,and characteristics of energy conversion and propagation.Formation of the MCC was related to southerly conveyed water vapor and energy to the north,with obvious water vapor exchange between the free atmosphere and the boundary layer.Continuous regeneration and development of the MCSs mainly relied on maintenance of an upward extension of a positive water vapor disturbance.The MCC rainstorm was triggered by large range of convergent ascending motion caused by a southerly jet,and easterly disturbance within the boundary layer.While a southerly fluctuation and easterly disturbance in the boundary layer were important triggers of the MCS rainstorms.Maintenance and development of the MCC and MCSs were linked to secondary circulation,resulting from convergence of Ekman non-equilibrium flow in the boundary layer.Both intensity and motion of the convergence centers in MCC and MCS cases were different.Clearly,sub-synoptic scale systems in the middle troposphere played a leading role in determining precipitation distribution during this event.Although mesoscale systems triggered by the sub-synoptic scale system induced the heavy rainfall,small-scale disturbances within the boundary layer determined its intensity and location.
基金supported by the National Natural Science Foundation of China(Grant Nos.11074151 and 11304185)
文摘Quantum dynamics calculations for the title reaction H（2S） ＋ S2（X3∑g） → SH（X2П） ＋S（3P） are performed byusing a globally accurate double many-body expansion potential energy surface [J. Phys. Chem. A 115 5274 （2011）]. The Chebyshev real wave packet propagation method is employed to obtain the dynamical information, such as reaction probability, initial state-specified integral cross section, and thermal rate constant. It is found not only that there is a reaction threshold near 0.7 eV in both reaction probabilities and integral cross section curves, but also that both the probability and cross section increase firstly and then decrease as the collision energy increases. The existence of the resonance structure in both the probability and cross section curves is ascribed to the deep potential well. The calculation of the rate constant reveals that the reaction occurring on the potential energy surface of the ground-state HS2 is slow to take place.
文摘This paper proposes new heuristic distributed parallel algorithms for search-ing and planning, which are based on the concepts of wave concurrent prop-agations and competitive activation mechanisms. These algorithms are char-acterized by simplicity and clearness of control strategies for searching, anddistinguished abilities in many aspects, such as high speed processing, widesuitability for searching AND/OR implicit graphs, and ease in hardware imple-mentation.
基金Supported jointly by the National Natural Science Foundation of China under Grant No.40675056Open Research Fund in Laboratory for Climate Studies of China Meteorological Administration under Grant No.LCS-2006-01.
文摘On the basis of studying wave package propagation, this paper investigated the relationship between high frequency wave package propagation and transient waves＇ evolvement or the subtropical high＇s latitudinal movement. The results showed that during winter the lifetime of wave package was longer and usually persisted for 7-10 days with a propagating speed of 2-10 m s-l. Usually they propagated southeastward at the beginning, then turned to northeast. During summer the lifetime and intensity of wave package became shorter and weaker. It availed development （attenuation） of troughs when the strong wave package center was intensified （weakened） which overlapped with trough. If strong wave package center kept overlapping with ridge, the ridge would abate later in a few days. Obvious jumping northward （retreating southward） processes of Western Pacific subtropical high （WPSH） were （not） usually related to strong wave package centers located at South China Sea area （South Asia area and Temperate Zone） for 5 days or longer. After two seasonal jumping processes, there were persisting strong wave package centers for 5 days or longer. WPSH retreating processes were also related to activities of strong wave package centers over South Asian area and temperate area as well as the strong wave package centers of typhoon, and all these centers persisted for 5 days or longer.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674198 and 11304185)
文摘According to a novel electronic ground-state potential energy surface of H2O^＋（X^4 A″）,we calculate the reaction probabilities and the integral cross section for the titled reaction O^＋＋ D2→OD^＋＋ D by the Chebyshev wave packet propagation method.The reaction probabilities in a collision-energy range of 0.0 e V–1.0 e V show an oscillatory structure for the O^＋＋ D2 reaction due to the existence of the potential well.Compared with the results of Martinez et al.,the present integral cross section is large,which is in line with experimental data.
