芦山M_S7.0地震前近震源区地形变熵特征研究

2013年4月20日芦山MS7.0地震是继2008年汶川MS8.0地震后发生在龙门山断裂带的又一强震,与汶川地震相似,该震临震前在近震源区未观测到显著的异常变化。为研究其临震前形变特征,本文根据信息熵理论对芦山MS7.0地震前近震源区的连续形变观测资料进行了年变熵率值分析,并研究其时序上的分布特征。结果表明,震前近震源区台站地倾斜形变熵均表现出减熵现象,时序的年尺度熵结果表明,汶川MS8.0地震对芦山MS7.0地震具有一定的触发作用,且震中区的EW向和NS向分量具有高度一致的熵变趋势。

小实验大道理——从热缩片小制品DIY看高分子材料的熵致形变

这是一项利用热缩材料的特性可以“自己动手做”(Do It Yourself,DIY)小制品的科普项目。通过该项目,公众可以初步了解高分子材料的熵致形变原理,本文还介绍了该项目在化学科普活动中的初步成效与特点。

A Note on Friedmann Equation of FRW Universe in Deformed Hoava-Lifshitz Gravity from Entropic Force

With entropic interpretation of gravity proposed by Verlinde, we obtain the Friedmann equation of the Friedmann Robertson-Walker universe for the deformed Hofava-Lifshitz gravity. It is shown that, when the parameter of Hofava-Lifshitz gravity ω →∞, the modified Friedmann equation will go back to the one in Einstein gravity. This results may imply that the entropic interpretation of gravity is effective for the deformed Hofava-Lifshitz gravity.

Hawking Tunneling Radiation of Black Holes in Deformed Horava-Lifshitz Gravity

Tunneling of scalar particles and Dirac particles from a black hole in the deformed Horava-Lifshitz gravity is discussed in this paper. We consider the case that the dynamical coupling constant λ= 1, when it reduces to Einstein＇s General Relativity at large scales and the black hole behaves like the Reissner-Nordstr6m black hole. The result shows that though the black hole entropy bears logarithmic correction, the tunneling probability is still related to its differences for the scalar particles and Dirac particles.

Research on the detecting methods of singularity in deformation signal based on two kinds of wavelet entropy

There are various influencing factors that affect the deformation observation, and deformation signals show differ- ent characteristics under different scales. Wavelet analysis possesses multi-scale property, and the information entropy has great representational capability to the complexity of information. By hamming window to the wavelet coefficients and windowed wavelet energy obtained by multi-resolution analysis （MRA）, it can be achieved to measure the wavelet time entropy （WTE） and wavelet energy entropy （WEE）. The paper established deformation signals, selected the parameters, and compared the sin- gularity detection ability and anti-noise ability of two kinds of wavelet entropy and applied them to the singularity detection at the GPS continuously operating reference stations. It is shown that the WTE performs well in weak singularity information de- tection in finite frequency components signals and the WEE is more suitable for detecting the singularity in the signals with complex, strong background noise.

Size-dependent mechanical properties and deformation mechanisms in Cu/NbMoTaW nanolaminates

High entropy alloys(HEAs)have attracted extensive attention due to their excellent properties in harsh environments.Here,we introduced the HEA NbMoTaW into the laminated structure to synthesize the Cu/HEA nanolaminates(NLs)with equal layer thickness h spanning from 5 to 100 nm,and comparatively investigated the size dependent mechanical properties and plastic deformation.The experimental results demonstrated that the hardness of Cu/HEA NLs increased with decreasing h,and reached a plateau at h≤50 nm,while the strain rate sensitivity m unexpectedly went through a maximum with reducing h.The emergence of maximum m results from a transition from the synergetic effect of crystalline constituents to the competitive effect between crystalline Cu and amorphous-like NbMoTaW.Microstructural examinations revealed that shear banding caused by the incoherent Cu/HEA interfaces occurred under severe deformation,and the soft Cu layers dominated plastic deformation of Cu/HEA NLs with large h.