In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer （PDPA） and simulated the system behavior by ...In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer （PDPA） and simulated the system behavior by using both a Reynolds-averaged Navier-Stokes （RANS） model and a large-eddy simulation （LES）. The results of the measurements yield the axial and radial time-averaged velocities as well as the fluctuation velocities of gas and three particle-size groups （30μm, 50μm, and 95μm） and the gasparticle velocity correlation for 30μm and 50μm particles. From the measurements, theoretical analysis, and simulation, it is found that the two-phase velocity correlation of sudden-expansion flows, like that of jet flows, is less than the gas and particle Reynolds stresses. What distinguishes the two-phase velocity correlations of sudden-expansion flow from those of jet and channel flows is the absence of a clear relationship between the two-phase velocity correlation and particle size in sudden-expansion flows. The measurements, theoretical analysis, and numerical simulation all lead to the above-stated conclusions. Quantitatively, the results of the LES are better than those of the RANS model.展开更多
Intense human activities have greatly changed the flood generation conditions in most areas of the world, and have destroyed the consistency in the annual flood peak and volume series. For design flood estimation, coa...Intense human activities have greatly changed the flood generation conditions in most areas of the world, and have destroyed the consistency in the annual flood peak and volume series. For design flood estimation, coaxial correlation diagram and conceptual hydrological model are two frequently used tools to adjust and reconstruct the flood series under human disturbance. This study took a typical mountain catchment of the Haihe River Basin as an example to investigate the effects of human activities on flood regime and to compare and assess the two adjustment methods. The main purpose is to construct a conceptual hydrological model which can incorporate the effects of human activities. The results show that the coaxial correlation diagram is simple and widely-used, but can only adjust the time series of total flood volumes. Therefore, it is only applicable under certain conditions(e.g. There is a strong link between the flood peaks and volumes and the link is not significantly affected by human activities). The conceptual model is a powerful tool to adjust the time series of both flood peak flows and flood volumes over different durations provided that it is closely related to the catchment hydrological characteristics, specifically accounting for the effects of human activities, and incorporating expert knowledge when estimating or calibrating parameters. It is suggested that the two methods should be used together to cross check each other.展开更多
Mountain glaciers are sensitive to environment. It is important to acquire ice flow velocities over time for glacier research and hazard forecast. For this paper, cross-correlating of optical images is used to monitor...Mountain glaciers are sensitive to environment. It is important to acquire ice flow velocities over time for glacier research and hazard forecast. For this paper, cross-correlating of optical images is used to monitor ice flow velocities, and an improvement, which is called ＂moving grid,＂ is made to this method. For this research, two remote-sensing images in a certain glacier area, dur-ing different times are selected. The first image is divided into grids, and we calculated the correlation coefficient of each window in the grid with the window on the second image. The window with the highest correlation coefficient is considered the counter-part one on the first image. The displacement of the two corresponding windows is the movement of the glacier, and it is used to calculate glacier surface velocity. Compared to the traditional way of dividing an image with ascertain grid, this method uses small steps to move the grid from one location to another adjacent location until the whole glacier area is covered in the image, thus in-creasing corresponding point density. We selected a glacier in the Tianshan Mountains for this experiment and used two re-mote-sensing images with a 10-year interval to determine this method.展开更多
In this study,we employ the maximum likelihood estimator(MLE)to investigate the relationship between initial-state fluctuations and final-state anisotropies in relativistic heavy-ion collisions.The granularity of the ...In this study,we employ the maximum likelihood estimator(MLE)to investigate the relationship between initial-state fluctuations and final-state anisotropies in relativistic heavy-ion collisions.The granularity of the initial state,reflecting fluctuations in the initial conditions(ICs),is modeled using a peripheral tube model.In addition to differential flow,our analysis focuses on a class of more sensitive observables known as flow factorization.Specifically,we evaluate these observables using the MLE,an asymptotically normal and unbiased tool in standard statistical inference.Our findings show that the resulting differential flow remains essentially unchanged for different ICs defined by the peripheral tube model.The resulting harmonic coefficients obtained using the MLE and multiparticle cumulants are found to be consistent.However,the calculated flow factorizations show significant variations depending on both the IC and estimators,which is attributed to their sensitivity to initial-state fluctuations.Thus,we argue that the MLE offers a compelling alternative to standard methods,such as multi-particle correlators,particularly for sensitive observables constructed from higher moments of the azimuthal distribution.展开更多
In dielectrics and semiconductors, a plasma model of the generation and slip of dislocations is considered, where under shock loads in a generalized space of rectangular pulses an alternating field forms a distributio...In dielectrics and semiconductors, a plasma model of the generation and slip of dislocations is considered, where under shock loads in a generalized space of rectangular pulses an alternating field forms a distribution of pairs of photoelectrons and cations;these electrons with velocities V<sub>e</sub> create δ-collisions with cold plasma from free electrons and holes with masses m<sub>e</sub> and m<sub>h</sub> (m<sub>h</sub> <span style="white-space:normal;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">≫ m<sub>e</sub>), they emit and absorb longitudinal electron plasma waves whose phase velocities w<sub>pw</sub> / k<sub>pw</sub> are close to or are equal to the velocities V<sub>e</sub>, while the frequencies w<sub>pw</sub> and wave numbers k<sub>pw</sub> of the wave packet of plasma waves are complex, the short-wave components <img src="Edit_3da65014-7fd8-4799-bcf1-02d90028f4e0.bmp" alt="" /> of this wave packet at k<sub>pw</sub> <span style="white-space:normal;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅ a<sub>e </sub><span style="white-space:nowrap;">≫ 1 (a<sub>e</sub> -Debye screening radius) decay in the core linear defect, and its long-wavelength components <img src="Edit_4481889b-5097-4d26-9019-b0322f5ff8d0.bmp" alt="" /> propagate in the region of the medium surrounding the core of the defect at k<sub>pw</sub> <span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅ a<sub>e</sub> <span style="white-space:nowrap;"><<span style="white-space:nowrap;"><span style="white-space:nowrap;">≅ 1. When a defect is generated, the distribution of cations under the influence of the internal Coulomb field shifts to the region of the first peak (protrusion) of the electron plasma wave, thereby forming a vacancy valley. When sliding under the influence of an external electric field, a cationic plasma wave consisting of a vacancy valley and two cationic protrusions moves against the background of an additional potential relief created by an electron plasma wave near the core of the defect. It has been shown that δ-collisions create flows of dynamic large-scale correlations of plasma fluctuations in the form of asymptotics of different-time correlators of density and potential fluctuations as t → +∞.展开更多
One dimensional non-steady, non-Darcy flow of water in a rock stratum was reduced into a system described by six ordinary differential equations involving five controlling parameters. Through response computations and...One dimensional non-steady, non-Darcy flow of water in a rock stratum was reduced into a system described by six ordinary differential equations involving five controlling parameters. Through response computations and time series analysis, chaotic behavior in the reduced system was discussed in details. Firstly, the dynamical response of the reduced system under a set of parameters was calculated, and the power spectrum of the attractor was obtained through fast Lagrangian transformation; then the phase space was reconstructed by fixing embedding dimension to be 6 and delay time to range from 1 to 20, and the correlation dimension of the attractor was calculated based on the curves under the coordinates of logarithm of correlation integral vs. logarithm of covering radius; and lastly, the Lyapunov indices of the attractor were calculated by using Gram-Schmit's orthogonalization method. The results show that the power spectrum of the attractor is continuous; the correlation dimension of the attractor is equal to 2.36; among the Lyapunov indices, LE1, LE2, LE3 are positive, LE5, LE6 are negative, and LE4 fluctuates near zero. All the analysis indicates that there may exist chaos in the system of non-steady, non-Darcy flow.展开更多
.Network performance estimation is a key enabler in achieving effi-cient network operation.It can assist in important tasks such as topology design,parameter tuning,and capacity planning.The most popular methods have r....Network performance estimation is a key enabler in achieving effi-cient network operation.It can assist in important tasks such as topology design,parameter tuning,and capacity planning.The most popular methods have recently been based on Convolutional Neural Network(CNN)or Recurrent Neural Net-work(RNN).However,many of these methods focus excessively on particular aspects of network features.They often overlook the diversity and complexity in network performance evaluation.This paper proposes a novel model TrafficNet for network performance estimation.This model uses aggregators to learn inter-flow correlations and intra-flow dependencies.By creating specialized feature extraction components for different types of network traffic and using the adap-tive mechanism to fuse these features,we aim to improve the accuracy of network performance evaluation.Furthermore,our extensive experiments have shown that TrafficNet can improve the Mean Squared Error(MSE)by 58.3%compared with the SOTA models.展开更多
基金supported by the National Natural Science Foundation of China (50606026 and 50736006)
文摘In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer （PDPA） and simulated the system behavior by using both a Reynolds-averaged Navier-Stokes （RANS） model and a large-eddy simulation （LES）. The results of the measurements yield the axial and radial time-averaged velocities as well as the fluctuation velocities of gas and three particle-size groups （30μm, 50μm, and 95μm） and the gasparticle velocity correlation for 30μm and 50μm particles. From the measurements, theoretical analysis, and simulation, it is found that the two-phase velocity correlation of sudden-expansion flows, like that of jet flows, is less than the gas and particle Reynolds stresses. What distinguishes the two-phase velocity correlations of sudden-expansion flow from those of jet and channel flows is the absence of a clear relationship between the two-phase velocity correlation and particle size in sudden-expansion flows. The measurements, theoretical analysis, and numerical simulation all lead to the above-stated conclusions. Quantitatively, the results of the LES are better than those of the RANS model.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41130639, 51179045, 41201028)the Nonprofit Industry Financial Program of MWR of China (201501022)
文摘Intense human activities have greatly changed the flood generation conditions in most areas of the world, and have destroyed the consistency in the annual flood peak and volume series. For design flood estimation, coaxial correlation diagram and conceptual hydrological model are two frequently used tools to adjust and reconstruct the flood series under human disturbance. This study took a typical mountain catchment of the Haihe River Basin as an example to investigate the effects of human activities on flood regime and to compare and assess the two adjustment methods. The main purpose is to construct a conceptual hydrological model which can incorporate the effects of human activities. The results show that the coaxial correlation diagram is simple and widely-used, but can only adjust the time series of total flood volumes. Therefore, it is only applicable under certain conditions(e.g. There is a strong link between the flood peaks and volumes and the link is not significantly affected by human activities). The conceptual model is a powerful tool to adjust the time series of both flood peak flows and flood volumes over different durations provided that it is closely related to the catchment hydrological characteristics, specifically accounting for the effects of human activities, and incorporating expert knowledge when estimating or calibrating parameters. It is suggested that the two methods should be used together to cross check each other.
基金supported by the National Basic Research Program of China (Grant No. 2009CB723901)863 program (2009AA12Z145)the Chinese Academy of Sciences (kzcx2-yw-301)
文摘Mountain glaciers are sensitive to environment. It is important to acquire ice flow velocities over time for glacier research and hazard forecast. For this paper, cross-correlating of optical images is used to monitor ice flow velocities, and an improvement, which is called ＂moving grid,＂ is made to this method. For this research, two remote-sensing images in a certain glacier area, dur-ing different times are selected. The first image is divided into grids, and we calculated the correlation coefficient of each window in the grid with the window on the second image. The window with the highest correlation coefficient is considered the counter-part one on the first image. The displacement of the two corresponding windows is the movement of the glacier, and it is used to calculate glacier surface velocity. Compared to the traditional way of dividing an image with ascertain grid, this method uses small steps to move the grid from one location to another adjacent location until the whole glacier area is covered in the image, thus in-creasing corresponding point density. We selected a glacier in the Tianshan Mountains for this experiment and used two re-mote-sensing images with a 10-year interval to determine this method.
基金under the project Institutos Nacionais de Ciências e Tecnologia-Física Nuclear e Aplicacoes(INCT/FNA)Proc.(464898/2014-5)Supported by the Center for Scientific Computing(NCC/GridUNESP)of Sao Paulo State University(UNESP)+6 种基金the funding from the Physics Master Teacher Studio of Guangsha Universitythe support of the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22-3453)the support of the National Natural Science Foundation of China(12347101)financial support from Brazilian agencies Fundacao de AmparoàPesquisa do Estado de Sao Paulo(FAPESP)Fundacao de AmparoàPesquisa do Estado do Rio de Janeiro(FAPERJ)Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nível Superior(CAPES)。
文摘In this study,we employ the maximum likelihood estimator(MLE)to investigate the relationship between initial-state fluctuations and final-state anisotropies in relativistic heavy-ion collisions.The granularity of the initial state,reflecting fluctuations in the initial conditions(ICs),is modeled using a peripheral tube model.In addition to differential flow,our analysis focuses on a class of more sensitive observables known as flow factorization.Specifically,we evaluate these observables using the MLE,an asymptotically normal and unbiased tool in standard statistical inference.Our findings show that the resulting differential flow remains essentially unchanged for different ICs defined by the peripheral tube model.The resulting harmonic coefficients obtained using the MLE and multiparticle cumulants are found to be consistent.However,the calculated flow factorizations show significant variations depending on both the IC and estimators,which is attributed to their sensitivity to initial-state fluctuations.Thus,we argue that the MLE offers a compelling alternative to standard methods,such as multi-particle correlators,particularly for sensitive observables constructed from higher moments of the azimuthal distribution.
文摘In dielectrics and semiconductors, a plasma model of the generation and slip of dislocations is considered, where under shock loads in a generalized space of rectangular pulses an alternating field forms a distribution of pairs of photoelectrons and cations;these electrons with velocities V<sub>e</sub> create δ-collisions with cold plasma from free electrons and holes with masses m<sub>e</sub> and m<sub>h</sub> (m<sub>h</sub> <span style="white-space:normal;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">≫ m<sub>e</sub>), they emit and absorb longitudinal electron plasma waves whose phase velocities w<sub>pw</sub> / k<sub>pw</sub> are close to or are equal to the velocities V<sub>e</sub>, while the frequencies w<sub>pw</sub> and wave numbers k<sub>pw</sub> of the wave packet of plasma waves are complex, the short-wave components <img src="Edit_3da65014-7fd8-4799-bcf1-02d90028f4e0.bmp" alt="" /> of this wave packet at k<sub>pw</sub> <span style="white-space:normal;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅ a<sub>e </sub><span style="white-space:nowrap;">≫ 1 (a<sub>e</sub> -Debye screening radius) decay in the core linear defect, and its long-wavelength components <img src="Edit_4481889b-5097-4d26-9019-b0322f5ff8d0.bmp" alt="" /> propagate in the region of the medium surrounding the core of the defect at k<sub>pw</sub> <span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅ a<sub>e</sub> <span style="white-space:nowrap;"><<span style="white-space:nowrap;"><span style="white-space:nowrap;">≅ 1. When a defect is generated, the distribution of cations under the influence of the internal Coulomb field shifts to the region of the first peak (protrusion) of the electron plasma wave, thereby forming a vacancy valley. When sliding under the influence of an external electric field, a cationic plasma wave consisting of a vacancy valley and two cationic protrusions moves against the background of an additional potential relief created by an electron plasma wave near the core of the defect. It has been shown that δ-collisions create flows of dynamic large-scale correlations of plasma fluctuations in the form of asymptotics of different-time correlators of density and potential fluctuations as t → +∞.
基金supported by the National Natural Science Foundation of China (No.50874104)
文摘One dimensional non-steady, non-Darcy flow of water in a rock stratum was reduced into a system described by six ordinary differential equations involving five controlling parameters. Through response computations and time series analysis, chaotic behavior in the reduced system was discussed in details. Firstly, the dynamical response of the reduced system under a set of parameters was calculated, and the power spectrum of the attractor was obtained through fast Lagrangian transformation; then the phase space was reconstructed by fixing embedding dimension to be 6 and delay time to range from 1 to 20, and the correlation dimension of the attractor was calculated based on the curves under the coordinates of logarithm of correlation integral vs. logarithm of covering radius; and lastly, the Lyapunov indices of the attractor were calculated by using Gram-Schmit's orthogonalization method. The results show that the power spectrum of the attractor is continuous; the correlation dimension of the attractor is equal to 2.36; among the Lyapunov indices, LE1, LE2, LE3 are positive, LE5, LE6 are negative, and LE4 fluctuates near zero. All the analysis indicates that there may exist chaos in the system of non-steady, non-Darcy flow.
文摘.Network performance estimation is a key enabler in achieving effi-cient network operation.It can assist in important tasks such as topology design,parameter tuning,and capacity planning.The most popular methods have recently been based on Convolutional Neural Network(CNN)or Recurrent Neural Net-work(RNN).However,many of these methods focus excessively on particular aspects of network features.They often overlook the diversity and complexity in network performance evaluation.This paper proposes a novel model TrafficNet for network performance estimation.This model uses aggregators to learn inter-flow correlations and intra-flow dependencies.By creating specialized feature extraction components for different types of network traffic and using the adap-tive mechanism to fuse these features,we aim to improve the accuracy of network performance evaluation.Furthermore,our extensive experiments have shown that TrafficNet can improve the Mean Squared Error(MSE)by 58.3%compared with the SOTA models.
