A Hall magnetohydrodynamics （MHD） simulation is carried out to study the dynamic process of double tearing mode. The results indicated that the growth rates in the earlier nonlinear and transition phases agree with ...A Hall magnetohydrodynamics （MHD） simulation is carried out to study the dynamic process of double tearing mode. The results indicated that the growth rates in the earlier nonlinear and transition phases agree with the previous results. With further development of reconnection, the current sheet thickness is much smaller than the ion inertia length, which leads to a strong influence of the Hall effects. As a result, the reconnection in the late nonlinear phase exhibits an explosive nature with a time scale nearly independent of resistivity. A localized and severely intensified current density is observed and the maximum kinetic energy is over one order of magnitude higher in Hall MHD than that in resistive MHD.展开更多
Using the Fourier helical decomposition, we obtain the absolute statistical equilibrium spectra of left- and right-handed helical modes in the incompressible ideal Hall magnetohydrodynamics (MHD). It is shown that the...Using the Fourier helical decomposition, we obtain the absolute statistical equilibrium spectra of left- and right-handed helical modes in the incompressible ideal Hall magnetohydrodynamics (MHD). It is shown that the left-handed helical modes play a major role on the spectral transfer properties of turbulence when the generalized helicity and magnetic helicity are both positive. In contrast, the right-handed helical modes will play a major role when both are negative. Furthermore, we also find that if the generalized helicity and magnetic helicity have opposite signs, the tendency of equilibrium spectra to condense at the large or small wave numbers will be presented in different helical sectors. This indicates that the generalized helicity dominates the forward cascade and the magnetic helicity dominates the inverse cascade properties of the Hall MHD turbulence.展开更多
为提高医院EPC项目管理效率,首先,依据霍尔的三维结构模式(Hard System Methodology,HSM)并结合医院工程总承包(Engineering Procurement Construction,EPC)项目的特点,构建了一个涵盖业务、组织、过程、信息、制度和资源六大子系统的医...为提高医院EPC项目管理效率,首先,依据霍尔的三维结构模式(Hard System Methodology,HSM)并结合医院工程总承包(Engineering Procurement Construction,EPC)项目的特点,构建了一个涵盖业务、组织、过程、信息、制度和资源六大子系统的医院EPC项目管理协同系统模型,基于此建立了医院EPC管理协同度评价指标体系;然后,运用改进的层次分析法确定指标权重,并结合序参量功效函数法对项目协同度进行量化计算,以此构建了医院EPC项目管理协同度评价模型;最后,以济南市某医院EPC项目为例,分析得出该项目各阶段的管理协同度、各子系统有序度及各序参量指标的敏感性程度。结果表明:该项目设计阶段和采购阶段的管理协同度处于低度协同水平,施工阶段处于低度不协同水平;在各子系统中,制度协同、业务协同、过程协同的有序度较低,应针对识别出的高敏感性指标进行改进。展开更多
基金National Science Foundation of China(Nos.40474058,40536030 and 10575031)
文摘A Hall magnetohydrodynamics （MHD） simulation is carried out to study the dynamic process of double tearing mode. The results indicated that the growth rates in the earlier nonlinear and transition phases agree with the previous results. With further development of reconnection, the current sheet thickness is much smaller than the ion inertia length, which leads to a strong influence of the Hall effects. As a result, the reconnection in the late nonlinear phase exhibits an explosive nature with a time scale nearly independent of resistivity. A localized and severely intensified current density is observed and the maximum kinetic energy is over one order of magnitude higher in Hall MHD than that in resistive MHD.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11375190 and 11547137
文摘Using the Fourier helical decomposition, we obtain the absolute statistical equilibrium spectra of left- and right-handed helical modes in the incompressible ideal Hall magnetohydrodynamics (MHD). It is shown that the left-handed helical modes play a major role on the spectral transfer properties of turbulence when the generalized helicity and magnetic helicity are both positive. In contrast, the right-handed helical modes will play a major role when both are negative. Furthermore, we also find that if the generalized helicity and magnetic helicity have opposite signs, the tendency of equilibrium spectra to condense at the large or small wave numbers will be presented in different helical sectors. This indicates that the generalized helicity dominates the forward cascade and the magnetic helicity dominates the inverse cascade properties of the Hall MHD turbulence.
文摘为提高医院EPC项目管理效率,首先,依据霍尔的三维结构模式(Hard System Methodology,HSM)并结合医院工程总承包(Engineering Procurement Construction,EPC)项目的特点,构建了一个涵盖业务、组织、过程、信息、制度和资源六大子系统的医院EPC项目管理协同系统模型,基于此建立了医院EPC管理协同度评价指标体系;然后,运用改进的层次分析法确定指标权重,并结合序参量功效函数法对项目协同度进行量化计算,以此构建了医院EPC项目管理协同度评价模型;最后,以济南市某医院EPC项目为例,分析得出该项目各阶段的管理协同度、各子系统有序度及各序参量指标的敏感性程度。结果表明:该项目设计阶段和采购阶段的管理协同度处于低度协同水平,施工阶段处于低度不协同水平;在各子系统中,制度协同、业务协同、过程协同的有序度较低,应针对识别出的高敏感性指标进行改进。
