In this paper, the cement paste and the mortar were tested using the PF-QNM technique. It is shown that the PF-QNM technique is very powerful to characterize the mechanical properties of micro-and nanostructures in th...In this paper, the cement paste and the mortar were tested using the PF-QNM technique. It is shown that the PF-QNM technique is very powerful to characterize the mechanical properties of micro-and nanostructures in the cement-based materials. It does not have strict requirements for test environment and it does not damage the surface of the material. High-resolution images can be obtained very easily, and they can be analyzed statistically. The test results show that PF-QNM analysis can test not only the mechanical properties of the cement paste, but also investigate the interfacial regions in the cement-based material, including the variation in the mechanical properties of interface regions and the extension of the interfacial regions. During the test, care must be taken to choose the size of test area;indeed, a test area too small is not representative but too large leads to lack of stability. The recommended side is a square with a length of in the range 10-30 μm.展开更多
The massless scalar quasiaormal modes （QNMs） of a stationary axisymmetric Einstein-Maxwell dilato-axioa （EMDA） black hole are calculated numerically using the continued fraction method first proposed by Leaver. Th...The massless scalar quasiaormal modes （QNMs） of a stationary axisymmetric Einstein-Maxwell dilato-axioa （EMDA） black hole are calculated numerically using the continued fraction method first proposed by Leaver. The fundamental quasinormal frequencies （slowly damped QNMs） are obtained and the peculiar behaviours of them are studied. It is shown that these frequencies depend on the dilaton parameter D, the rotational parameter a, the multiple moment l and the azimuthal number m, and have the same values with other authors at the Schwarzschild and Kerr limit.展开更多
原子力显微术(Atomic force microscopy,AFM)的力学成像模式可在高分辨成像的同时,定量测量材料的力学性质。然而,对尺度小、质地薄而软的生物分子的弹性模量的测量仍然是一个挑战。本文以脱氧核糖核酸(Deoxyribonucleic acid,DNA)折纸...原子力显微术(Atomic force microscopy,AFM)的力学成像模式可在高分辨成像的同时,定量测量材料的力学性质。然而,对尺度小、质地薄而软的生物分子的弹性模量的测量仍然是一个挑战。本文以脱氧核糖核酸(Deoxyribonucleic acid,DNA)折纸为检测样品,将峰值力定量纳米力学模式(Peak Force Quantitative Nanomechanical Mapping,PF-QNM)作为测量手段研究了DNA分子的力学性质,探索不同作用力对DNA折纸弹性模量的影响。结果表明,当峰值力控制在80-100 p N时,峰值力成像稳定,获得的杨氏模量维持在约10 MPa。与传统力曲线阵列模式(Force volume mapping,FV)相比较,在小力区(<100 p N),两种方法符合性较好。这种峰值力定量纳米力学模式为DNA分子定量力学性质研究提供了一种简便而有效的研究方法。展开更多
Quasinormal modes(QNMs)for massless and massive Dirac perturbations of Born-Infeld black holes(BHs)in higher dimensions are investigated.Solving the corresponding master equation in accordance with hypergeometric func...Quasinormal modes(QNMs)for massless and massive Dirac perturbations of Born-Infeld black holes(BHs)in higher dimensions are investigated.Solving the corresponding master equation in accordance with hypergeometric functions and the QNMs are evaluated.We discuss the relationships between QNM frequencies and spacetime dimensions.Meanwhile,we also discuss the stability of the Born-Infeld BH by calculating the temporal evolution of the perturbation field.Both the perturbation frequencies and the decay rate increase with increasing dimension of spacetime n.This shows that the Born-Infeld BHs become more and more unstable at higher dimensions.Furthermore,the traditional finite difference method is improved,so that it can be used to calculate the massive Dirac field.We also elucidate the dynamic evolution of Born-Infeld BHs in a massive Dirac field.Because the number of extra dimensions is related to the string scale,there is a relationship between the spacetime dimension n and the properties of Born-Infeld BHs that might be advantageous for the development of extra-dimensional brane worlds and string theory.展开更多
In this paper, we describe quasinormal modes（QNMs） for gravitational perturbations of Einstein-GaussBonnet black holes（BHs） in higher dimensional spacetimes, and derive the corresponding parameters of such black h...In this paper, we describe quasinormal modes（QNMs） for gravitational perturbations of Einstein-GaussBonnet black holes（BHs） in higher dimensional spacetimes, and derive the corresponding parameters of such black holes in three types of spacetime（flat, de Sitter（d S） and anti-de Sitter（Ad S））. Our attention is concentrated on discussing the（in）stability of Einstein-Gauss-Bonnet Ad S BHs through the temporal evolution of all types of gravitational perturbation fields（tensor, vector and scalar）. It is concluded that the potential functions in vector and scalar gravitational perturbations have negative regions, which suppress quasinormal ringing. Furthermore,the influences of the Gauss-Bonnet coupling parameter α, the number of dimensions n and the angular momentum quantum number l on the Einstein-Gauss-Bonnet Ad S BHs quasinormal spectrum are analyzed. The QNM frequencies have greater oscillation and lower damping rate with the growth of α. This indicates that QNM frequencies become increasingly unstable with large α. Meanwhile, the dynamic evolutions of the perturbation field are compliant with the results of computation from the Horowitz and Hubeny method. Because the number of extra dimensions is connected with the string scale, the relationship between α and properties of Einstein-Gauss-Bonnet Ad S BHs might be beneficial for the exploitation of string theory and extra-dimensional brane worlds.展开更多
Quasinormal modes （QNMs） for Dirac perturbations off（R） black holes （BHs） are described in this paper, involving two types of f（R） solution： f（R） （Sehwarzschild） BHs and f（R） （Maxwell） BHs. With the f...Quasinormal modes （QNMs） for Dirac perturbations off（R） black holes （BHs） are described in this paper, involving two types of f（R） solution： f（R） （Sehwarzschild） BHs and f（R） （Maxwell） BHs. With the finite difference method, the stability of the f（R） black holes （BHs） is analysed and the threshold range off（R） （Schwarzschild） BHs and f（R） （Maxwell） BHs is defined respectively. The results show that due to the presence of the correction factor Ro, the damping rate of Dirac field decreases. Meanwhile, the influence of angular quantum number values [k] on the f（R） BHs is investigated. The results indicate that the QNMs oscillation becomes tenser and damping speed slowly decreases with ]k[ increasing. Furthermore, under the Dirac perturbation, the stability off（R） solutions can be reflected in the manner of Dirac QNMs. The relationships between the QNMs and the parameters （]k], charge Q and mass m） are discussed in massless, and massive cases, by contrast to the classical BHs.展开更多
基金Funded by the National Natural Science Foundation of China(51778582&51879235)the National Key R&D Plan(2017YFC0804809)
文摘In this paper, the cement paste and the mortar were tested using the PF-QNM technique. It is shown that the PF-QNM technique is very powerful to characterize the mechanical properties of micro-and nanostructures in the cement-based materials. It does not have strict requirements for test environment and it does not damage the surface of the material. High-resolution images can be obtained very easily, and they can be analyzed statistically. The test results show that PF-QNM analysis can test not only the mechanical properties of the cement paste, but also investigate the interfacial regions in the cement-based material, including the variation in the mechanical properties of interface regions and the extension of the interfacial regions. During the test, care must be taken to choose the size of test area;indeed, a test area too small is not representative but too large leads to lack of stability. The recommended side is a square with a length of in the range 10-30 μm.
基金Project supported by the National Natural Science Foundation of China （Grant No 10473004）, the FADEDD （Grant No 200317）, and the SRFDP （Grant No 20040542003）.
文摘The massless scalar quasiaormal modes （QNMs） of a stationary axisymmetric Einstein-Maxwell dilato-axioa （EMDA） black hole are calculated numerically using the continued fraction method first proposed by Leaver. The fundamental quasinormal frequencies （slowly damped QNMs） are obtained and the peculiar behaviours of them are studied. It is shown that these frequencies depend on the dilaton parameter D, the rotational parameter a, the multiple moment l and the azimuthal number m, and have the same values with other authors at the Schwarzschild and Kerr limit.
文摘原子力显微术(Atomic force microscopy,AFM)的力学成像模式可在高分辨成像的同时,定量测量材料的力学性质。然而,对尺度小、质地薄而软的生物分子的弹性模量的测量仍然是一个挑战。本文以脱氧核糖核酸(Deoxyribonucleic acid,DNA)折纸为检测样品,将峰值力定量纳米力学模式(Peak Force Quantitative Nanomechanical Mapping,PF-QNM)作为测量手段研究了DNA分子的力学性质,探索不同作用力对DNA折纸弹性模量的影响。结果表明,当峰值力控制在80-100 p N时,峰值力成像稳定,获得的杨氏模量维持在约10 MPa。与传统力曲线阵列模式(Force volume mapping,FV)相比较,在小力区(<100 p N),两种方法符合性较好。这种峰值力定量纳米力学模式为DNA分子定量力学性质研究提供了一种简便而有效的研究方法。
基金Supported by Natural Science Foundation Project of Qinghai Office of Science and Technology(2019-ZJ-973Q,2019-ZJ-A10)National Natural Science Foundation of China(11873001)。
文摘Quasinormal modes(QNMs)for massless and massive Dirac perturbations of Born-Infeld black holes(BHs)in higher dimensions are investigated.Solving the corresponding master equation in accordance with hypergeometric functions and the QNMs are evaluated.We discuss the relationships between QNM frequencies and spacetime dimensions.Meanwhile,we also discuss the stability of the Born-Infeld BH by calculating the temporal evolution of the perturbation field.Both the perturbation frequencies and the decay rate increase with increasing dimension of spacetime n.This shows that the Born-Infeld BHs become more and more unstable at higher dimensions.Furthermore,the traditional finite difference method is improved,so that it can be used to calculate the massive Dirac field.We also elucidate the dynamic evolution of Born-Infeld BHs in a massive Dirac field.Because the number of extra dimensions is related to the string scale,there is a relationship between the spacetime dimension n and the properties of Born-Infeld BHs that might be advantageous for the development of extra-dimensional brane worlds and string theory.
基金Supported by FAPESP(2012/08934-0)National Natural Science Foundation of China(11205254,11178018,11375279,11605015)+1 种基金the Natural Science Foundation Project of CQ CSTC(2011BB0052)the Fundamental Research Funds for the Central Universities(106112016CDJXY300002,106112017CDJXFLX0014,CDJRC10300003)
文摘In this paper, we describe quasinormal modes（QNMs） for gravitational perturbations of Einstein-GaussBonnet black holes（BHs） in higher dimensional spacetimes, and derive the corresponding parameters of such black holes in three types of spacetime（flat, de Sitter（d S） and anti-de Sitter（Ad S））. Our attention is concentrated on discussing the（in）stability of Einstein-Gauss-Bonnet Ad S BHs through the temporal evolution of all types of gravitational perturbation fields（tensor, vector and scalar）. It is concluded that the potential functions in vector and scalar gravitational perturbations have negative regions, which suppress quasinormal ringing. Furthermore,the influences of the Gauss-Bonnet coupling parameter α, the number of dimensions n and the angular momentum quantum number l on the Einstein-Gauss-Bonnet Ad S BHs quasinormal spectrum are analyzed. The QNM frequencies have greater oscillation and lower damping rate with the growth of α. This indicates that QNM frequencies become increasingly unstable with large α. Meanwhile, the dynamic evolutions of the perturbation field are compliant with the results of computation from the Horowitz and Hubeny method. Because the number of extra dimensions is connected with the string scale, the relationship between α and properties of Einstein-Gauss-Bonnet Ad S BHs might be beneficial for the exploitation of string theory and extra-dimensional brane worlds.
基金Supported by FAPESP No.2012/08934-0National Natural Science Foundation of China under Grant Nos.11205254,11178018,11375279,11605015+1 种基金the Natural Science Foundation Project of CQ CSTC 2011BB0052the Fundamental Research Funds for the Central Universities 106112016CDJXY300002 and CDJRC10300003
文摘Quasinormal modes （QNMs） for Dirac perturbations off（R） black holes （BHs） are described in this paper, involving two types of f（R） solution： f（R） （Sehwarzschild） BHs and f（R） （Maxwell） BHs. With the finite difference method, the stability of the f（R） black holes （BHs） is analysed and the threshold range off（R） （Schwarzschild） BHs and f（R） （Maxwell） BHs is defined respectively. The results show that due to the presence of the correction factor Ro, the damping rate of Dirac field decreases. Meanwhile, the influence of angular quantum number values [k] on the f（R） BHs is investigated. The results indicate that the QNMs oscillation becomes tenser and damping speed slowly decreases with ]k[ increasing. Furthermore, under the Dirac perturbation, the stability off（R） solutions can be reflected in the manner of Dirac QNMs. The relationships between the QNMs and the parameters （]k], charge Q and mass m） are discussed in massless, and massive cases, by contrast to the classical BHs.
