Low-ionization nuclear emission regions （LINERs） are present in a large fraction of local galaxies, while their connection to the more luminous active galactic nuclei （AGN） remains elusive. We analyze the narrow b...Low-ionization nuclear emission regions （LINERs） are present in a large fraction of local galaxies, while their connection to the more luminous active galactic nuclei （AGN） remains elusive. We analyze the narrow band images obtained by the Hubble Space Telescope （HST） in Hα＋[NII] and/or [OIII] band for 23 LINERs and low luminosity Seyfert galaxies in the sample of the Palomar Optical Spectroscopic Survey of nearby galaxies in an attempt to resolve the structure of Narrow Emission Line Regions （NLRs） of these objects. In all cases, NLRs are well resolved and their morphology differs from object to object. Clumps, linear structure, spiral arms or a ring are detected in a large fraction of the objects, while there is no significant difference between Seyfert galaxies and LINERs. We find that the NLR size and the narrow line luminosity are strongly correlated for both LINERs and low luminosity Seyfert galaxies, and that the size of Ha＋[NII] emission line region scales with Ha luminosity as RNLR ∝ LHα^0.44＋0.06, consistent with an extension of the NLR size-luminosity relation defined for luminous Seyfert galaxies and quasars, to two orders of magnitude lower in luminosity and to lower activity levels. Our results suggest that NLRs in LINERs are similar to those of Seyfert galaxies, and they are powered by the central active galactic nucleus.展开更多
The design of roof frame is one of the most important parts of LNG tank design.In China,however,the calculation of roof frame system of extra-large LNG tanks is currently faced with a series of problems.For example,th...The design of roof frame is one of the most important parts of LNG tank design.In China,however,the calculation of roof frame system of extra-large LNG tanks is currently faced with a series of problems.For example,there is no united yardstick on buckling characteristic value,the calculation is based on many assumptions,and the calculation is inconsistent with domestic specifications and stipulations.In view of these problems,the material non-linearity and structural non-linearity were introduced and the initial defect was taken into consideration.Then,the large non-linear finite element calculation software ABAQUS was adopted to carry out modeling on the roof frame and liner system of extra-large LNG tanks and calculate and analyze the force applied on them and their stability.Finally,a complete set of design algorithm for the roof frame and liner system of extra-large LNG tanks was established and applied to the design of a certain LNG tank(20×10^(4)m^(3))in China.It is indicated that this design algorithm can simulate the actual situations accurately.This design algorithm is structurally composed of shell units and beam units,and it is connected in the pattern of common node.Besides,force calculation is conducted in 10 operational modes and the buckling calculation in 7 operational modes,including all operational modes in the construction process of roof frame and liner system of LNG tanks.It is also revealed that the maximum stress on the roof frame is 125.7 MPa,that on the liner is 101.4 MPa and the minimum safety coefficient used for buckling calculation is 2.57.Under this system,the force and stability of the roof frame of LNG tanks are satisfactory.The research results can be used as reference for relevant design and calculation.展开更多
文摘Low-ionization nuclear emission regions （LINERs） are present in a large fraction of local galaxies, while their connection to the more luminous active galactic nuclei （AGN） remains elusive. We analyze the narrow band images obtained by the Hubble Space Telescope （HST） in Hα＋[NII] and/or [OIII] band for 23 LINERs and low luminosity Seyfert galaxies in the sample of the Palomar Optical Spectroscopic Survey of nearby galaxies in an attempt to resolve the structure of Narrow Emission Line Regions （NLRs） of these objects. In all cases, NLRs are well resolved and their morphology differs from object to object. Clumps, linear structure, spiral arms or a ring are detected in a large fraction of the objects, while there is no significant difference between Seyfert galaxies and LINERs. We find that the NLR size and the narrow line luminosity are strongly correlated for both LINERs and low luminosity Seyfert galaxies, and that the size of Ha＋[NII] emission line region scales with Ha luminosity as RNLR ∝ LHα^0.44＋0.06, consistent with an extension of the NLR size-luminosity relation defined for luminous Seyfert galaxies and quasars, to two orders of magnitude lower in luminosity and to lower activity levels. Our results suggest that NLRs in LINERs are similar to those of Seyfert galaxies, and they are powered by the central active galactic nucleus.
基金Project supported by the Special and Significant Project of China National Offshore Oil Corporation“Study on the design of full-containment large LNG storage tank and engineering applications”(No.:CNOOC-KJ125ZDXM14QD-04QD11).
文摘The design of roof frame is one of the most important parts of LNG tank design.In China,however,the calculation of roof frame system of extra-large LNG tanks is currently faced with a series of problems.For example,there is no united yardstick on buckling characteristic value,the calculation is based on many assumptions,and the calculation is inconsistent with domestic specifications and stipulations.In view of these problems,the material non-linearity and structural non-linearity were introduced and the initial defect was taken into consideration.Then,the large non-linear finite element calculation software ABAQUS was adopted to carry out modeling on the roof frame and liner system of extra-large LNG tanks and calculate and analyze the force applied on them and their stability.Finally,a complete set of design algorithm for the roof frame and liner system of extra-large LNG tanks was established and applied to the design of a certain LNG tank(20×10^(4)m^(3))in China.It is indicated that this design algorithm can simulate the actual situations accurately.This design algorithm is structurally composed of shell units and beam units,and it is connected in the pattern of common node.Besides,force calculation is conducted in 10 operational modes and the buckling calculation in 7 operational modes,including all operational modes in the construction process of roof frame and liner system of LNG tanks.It is also revealed that the maximum stress on the roof frame is 125.7 MPa,that on the liner is 101.4 MPa and the minimum safety coefficient used for buckling calculation is 2.57.Under this system,the force and stability of the roof frame of LNG tanks are satisfactory.The research results can be used as reference for relevant design and calculation.
