Strainmeters have been used to detect earthquake precursory anomalies in many countries. An innovated four-component strainmeter with four sensing units set at 45 degrees intervals, named SKZ strainmeter, was develope...Strainmeters have been used to detect earthquake precursory anomalies in many countries. An innovated four-component strainmeter with four sensing units set at 45 degrees intervals, named SKZ strainmeter, was developed and used in China. The design, with a few unique features, allows high-sensitivity monitoring of the regime of the crustal strain field, as well as the self-consistencies of the instrument. One of the most difficult problems in the earthquake precursory investigation is to efficiently detect anomalies from large amount of data. Pattern recognition of waveforms is widely used, but it is time-consuming and relies more or less investigator’s experience and decision. In this study, the consistency factors of the paired components were firstly shown to be utilized to detect anomalies possibly related with imminent earthquakes. Here, rather than using the consistency factors, the correlation coefficients of the two orthogonal strain data were used to detect. SKZ strainmeters have been installed at more than ten sites in China, exhibited high efficiency and reliability in precursory monitoring since. Anomalous variations from a few stations during two recent earthquakes in south China were analyzed. During normal stages, diurnal earth tides could be clearly observed with very little urban noises. Though the consistency factors may have near constant bias, their correlation coefficients remain near 1.0, greater than 0.99. During the imminent preparatory stage of earthquake occurrence, non-planar strain may appear and the correlation coefficients drop noticeably. The analysis showed that the correlation coefficient between the two orthogonal components is a useful parameter in post-processing of the strain data to detect precursory anomalies. The resultant resolving power is shown to be some one-order larger compared with previous methods.展开更多
The relationship between the as-cast microstructure and mechanical properties of the Al-12Si-3.SCu- 2Ni-0.8Mg alloys produced by permanent mold casting （PMC） and high pressure die casting （HPDC） is investigated. T...The relationship between the as-cast microstructure and mechanical properties of the Al-12Si-3.SCu- 2Ni-0.8Mg alloys produced by permanent mold casting （PMC） and high pressure die casting （HPDC） is investigated. The alloys in both PMC and HPDC consist of Al, Si, A15 Cu2 MgsSi6, Al3 CuNi, and Al Cu4Ni phase. However, the microstructure of the HPDC alloy is significantly refined. Compared to the PMC alloy, the ultimate tensile strength of the HPDC alloy is significantly increased from 244 MPa to 310 MPa, while the elongation shows a reverse trend at room temperature. At low stress and temperature range, slight variations of stress exponent and activation energy indicate that the minimum creep rate is controlled by the grain boundary creep. Then the minimum creep rate is higher for the specimen with the smaller grain size, where grain boundary creep is the dominant creep mechanism. At high stress region, the stress exponent for the PMC alloy and HPDC alloy is 5.18 and 3.07, respectively. The different stress exponents and activation energies measured at high stress and high temperature range indicates that the creep mechanism varies with the casting technologies.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.展开更多
Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation mode.At present,these devices...Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation mode.At present,these devices’noise-equivalent limits-of-detection lag far behind the free-space counterparts,leaving them incapable of most biosensing applications.Here we report a quasi-3D Fano resonance cavity and its fabrication method to fundamentally improve the quality factor and coupling efficiency for fiber-coupled surface plasmon resonance.In this device,the Fano resonance combines the high coupling efficiency of a Fabry-Pérot etalon and the high quality factor resonance of a plasmonic crystal cavity.The quasi-3D device was fabricated on a planar substrate and transferred to a single-mode fiber end-facet,which requires a low-adhesion yet surface-plasmon-tunneling interface between the device and the planar substrate.Such an interface was realized with a nanocap-slit unit structure,of which the plasmonic crystal was consisted.A noise-equivalent limit of detection of~10-7 RIU was experimentally obtained,allowing bovine serum albumin physical adsorption to be distinguished at ng mL-1 level concentrations.Therefore,breaking through the long-standing signal-to-noise ratio bottleneck,this work makes fiber end-facet surface plasmon devices into one of high sensitivity label-free sensing technologies.At the same time,it provides an enabling top-down fabrication technology for making 3D plasmonic structures on fiber end-facets at the nanometer scale.展开更多
Let G=(V,E)be a graph,for an element x∈V∪E,the open total neighborhood of x is denoted by N_(t)(x)={y|y is adjacent to x or y is incident with x,y∈V∪E},and Nt[x]=Nt(x)∪{x}is the closed one.A function f:V(G)∪E(G...Let G=(V,E)be a graph,for an element x∈V∪E,the open total neighborhood of x is denoted by N_(t)(x)={y|y is adjacent to x or y is incident with x,y∈V∪E},and Nt[x]=Nt(x)∪{x}is the closed one.A function f:V(G)∪E(G)→{−1,0,1}is said to be a mixed minus domination function(TMDF)of G if∑_(y∈Nt[x])f(y)≥1 holds for all x∈V(G)∪E(G).The mixed minus domination numberγ′_(tm)(G)of G is defined as γ′_(tm)(G)=min{∑x∈V∪E f(x)|f is a TMDF of G.In this paper,we obtain some lower bounds of the mixed minus domination number of G and give the exact values ofγ′_(tm)(G)when G is a cycle or a path.展开更多
文摘Strainmeters have been used to detect earthquake precursory anomalies in many countries. An innovated four-component strainmeter with four sensing units set at 45 degrees intervals, named SKZ strainmeter, was developed and used in China. The design, with a few unique features, allows high-sensitivity monitoring of the regime of the crustal strain field, as well as the self-consistencies of the instrument. One of the most difficult problems in the earthquake precursory investigation is to efficiently detect anomalies from large amount of data. Pattern recognition of waveforms is widely used, but it is time-consuming and relies more or less investigator’s experience and decision. In this study, the consistency factors of the paired components were firstly shown to be utilized to detect anomalies possibly related with imminent earthquakes. Here, rather than using the consistency factors, the correlation coefficients of the two orthogonal strain data were used to detect. SKZ strainmeters have been installed at more than ten sites in China, exhibited high efficiency and reliability in precursory monitoring since. Anomalous variations from a few stations during two recent earthquakes in south China were analyzed. During normal stages, diurnal earth tides could be clearly observed with very little urban noises. Though the consistency factors may have near constant bias, their correlation coefficients remain near 1.0, greater than 0.99. During the imminent preparatory stage of earthquake occurrence, non-planar strain may appear and the correlation coefficients drop noticeably. The analysis showed that the correlation coefficient between the two orthogonal components is a useful parameter in post-processing of the strain data to detect precursory anomalies. The resultant resolving power is shown to be some one-order larger compared with previous methods.
基金financial support of the National Key Research and Development Project of China (No. 2016YFB0301001)the Opening Fund of State Key Laboratory of Metal Matrix Composite (No. mmc-kdf16-03)Shanghai Jiao Tong University startup funding (No. 13x100040023)
文摘The relationship between the as-cast microstructure and mechanical properties of the Al-12Si-3.SCu- 2Ni-0.8Mg alloys produced by permanent mold casting （PMC） and high pressure die casting （HPDC） is investigated. The alloys in both PMC and HPDC consist of Al, Si, A15 Cu2 MgsSi6, Al3 CuNi, and Al Cu4Ni phase. However, the microstructure of the HPDC alloy is significantly refined. Compared to the PMC alloy, the ultimate tensile strength of the HPDC alloy is significantly increased from 244 MPa to 310 MPa, while the elongation shows a reverse trend at room temperature. At low stress and temperature range, slight variations of stress exponent and activation energy indicate that the minimum creep rate is controlled by the grain boundary creep. Then the minimum creep rate is higher for the specimen with the smaller grain size, where grain boundary creep is the dominant creep mechanism. At high stress region, the stress exponent for the PMC alloy and HPDC alloy is 5.18 and 3.07, respectively. The different stress exponents and activation energies measured at high stress and high temperature range indicates that the creep mechanism varies with the casting technologies.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.
基金supported by the National Natural Science Foundation of China(grant 61975253)the Science and Technology Commission of Shanghai Municipality(grant 21N31900200)the National Infrastructures for Translational Medicine(Shanghai) and the Lumieres(Xu Yuan)Biotechnology Company.
文摘Surface plasmon devices mounted at the end-facets of optical fibers are appealing candidates for rapid and point-of-care sensing applications,by offering a special dip-and-read operation mode.At present,these devices’noise-equivalent limits-of-detection lag far behind the free-space counterparts,leaving them incapable of most biosensing applications.Here we report a quasi-3D Fano resonance cavity and its fabrication method to fundamentally improve the quality factor and coupling efficiency for fiber-coupled surface plasmon resonance.In this device,the Fano resonance combines the high coupling efficiency of a Fabry-Pérot etalon and the high quality factor resonance of a plasmonic crystal cavity.The quasi-3D device was fabricated on a planar substrate and transferred to a single-mode fiber end-facet,which requires a low-adhesion yet surface-plasmon-tunneling interface between the device and the planar substrate.Such an interface was realized with a nanocap-slit unit structure,of which the plasmonic crystal was consisted.A noise-equivalent limit of detection of~10-7 RIU was experimentally obtained,allowing bovine serum albumin physical adsorption to be distinguished at ng mL-1 level concentrations.Therefore,breaking through the long-standing signal-to-noise ratio bottleneck,this work makes fiber end-facet surface plasmon devices into one of high sensitivity label-free sensing technologies.At the same time,it provides an enabling top-down fabrication technology for making 3D plasmonic structures on fiber end-facets at the nanometer scale.
基金This work was supported by the National Natural Science Foundation of China(No.11061014,11361024,11261019)the Science Foundation of Jiangxi Province(No.KJLD12067)The authors are grateful to the referees for their careful reading with corrections and especially the referee who draws our attention to the proof in Theorem 2.2,which let us improve the proof of Theorem 2.2,and correct this lower bound.
文摘Let G=(V,E)be a graph,for an element x∈V∪E,the open total neighborhood of x is denoted by N_(t)(x)={y|y is adjacent to x or y is incident with x,y∈V∪E},and Nt[x]=Nt(x)∪{x}is the closed one.A function f:V(G)∪E(G)→{−1,0,1}is said to be a mixed minus domination function(TMDF)of G if∑_(y∈Nt[x])f(y)≥1 holds for all x∈V(G)∪E(G).The mixed minus domination numberγ′_(tm)(G)of G is defined as γ′_(tm)(G)=min{∑x∈V∪E f(x)|f is a TMDF of G.In this paper,we obtain some lower bounds of the mixed minus domination number of G and give the exact values ofγ′_(tm)(G)when G is a cycle or a path.
