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1.
《中国物理 B》2021,30(5):50501-050501
We explore the robustness of a network against failures of vertices or edges where a fraction f of vertices is removed and an overload model based on betweenness is constructed. It is assumed that the load and capacity of vertex i are correlated with its betweenness centrality B_i as B_i~θ and(1 + α)Bθi(θ is the strength parameter, α is the tolerance parameter).We model the cascading failures following a local load preferential sharing rule. It is found that there exists a minimal αc when θ is between 0 and 1, and its theoretical analysis is given. The minimal αc characterizes the strongest robustness of a network against cascading failures triggered by removing a random fraction f of vertices. It is realized that the minimalαc increases with the increase of the removal fraction f or the decrease of average degree. In addition, we compare the robustness of networks whose overload models are characterized by degree and betweenness, and find that the networks based on betweenness have stronger robustness against the random removal of a fraction f of vertices. 相似文献
2.
In this paper, we use a method to determine some basic parameters for
the $\gamma$-ray loud blazars. The parameters include the central
black mass ($M$), the boosting factor ($\delta$), the propagation
angle (${\it {\it\Phi}}$), the distance along the axis to the site of
the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray
loud blazars with available variability time scales has been used to
discuss the above properties. In this method, the $\gamma$-ray
energy, the emission size and the property of the accretion disc
determine the absorption effect. If we take the intrinsic
$\gamma$-ray luminosity to be $\lambda$ times the Eddington
luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we
have the following results: the mass of the black hole is in the
range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or
$(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting
factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for
the $\gamma$-ray loud blazars. The parameters include the central
black mass ($M$), the boosting factor ($\delta$), the propagation
angle (${\it {\it\Phi}}$), the distance along the axis to the site of
the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray
loud blazars with available variability time scales has been used to
discuss the above properties. In this method, the $\gamma$-ray
energy, the emission size and the property of the accretion disc
determine the absorption effect. If we take the intrinsic
$\gamma$-ray luminosity to be $\lambda$ times the Eddington
luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we
have the following results: the mass of the black hole is in the
range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or
$(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting
factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for
the $\gamma$-ray loud blazars. The parameters include the central
black mass ($M$), the boosting factor ($\delta$), the propagation
angle (${\it {\it\Phi}}$), the distance along the axis to the site of
the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray
loud blazars with available variability time scales has been used to
discuss the above properties. In this method, the $\gamma$-ray
energy, the emission size and the property of the accretion disc
determine the absorption effect. If we take the intrinsic
$\gamma$-ray luminosity to be $\lambda$ times the Eddington
luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we
have the following results: the mass of the black hole is in the
range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or
$(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting
factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for
the $\gamma$-ray loud blazars. The parameters include the central
black mass ($M$), the boosting factor ($\delta$), the propagation
angle (${\it {\it\Phi}}$), the distance along the axis to the site of
the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray
loud blazars with available variability time scales has been used to
discuss the above properties. In this method, the $\gamma$-ray
energy, the emission size and the property of the accretion disc
determine the absorption effect. If we take the intrinsic
$\gamma$-ray luminosity to be $\lambda$ times the Eddington
luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we
have the following results: the mass of the black hole is in the
range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or
$(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting
factor ($\delta$) in the range of In this paper, we use a method to determine some basic parameters for
the $\gamma$-ray loud blazars. The parameters include the central
black mass ($M$), the boosting factor ($\delta$), the propagation
angle (${\it {\it\Phi}}$), the distance along the axis to the site of
the $\gamma$-ray production ($d$). A sample including 32 $\gamma$-ray
loud blazars with available variability time scales has been used to
discuss the above properties. In this method, the $\gamma$-ray
energy, the emission size and the property of the accretion disc
determine the absorption effect. If we take the intrinsic
$\gamma$-ray luminosity to be $\lambda$ times the Eddington
luminosity, i.e. $L_{\gamma}^{\rm in}=\lambda{L_{\rm Edd}}$, then we
have the following results: the mass of the black hole is in the
range of $(0.59-67.99)\times10^{7}M_{\odot} \ (\lambda=1.0)$ or
$(0.90-104.13)\times10^{7}M_{\odot} \ (\lambda=0.1)$; the boosting
factor ($\delta$) in the range of $0.16-2.09(\lambda=1.0)$ or
$0.24-2.86\ (\lambda=0.1)$; the angle (${\it\Phi}$) in the range of
$9.53^{\circ}-73.85^{\circ}\ (\lambda=1.0)$ or
$7.36^{\circ}-68.89^{\circ}\ (\lambda=0.1)$; and the distance
($d/R_{\rm g}$) in the range of $22.39-609.36\ (\lambda=1.0)$ or
$17.54-541.88\ (\lambda=0.1)$. 相似文献
3.
Guiding of 150 keV O6+ ions through nanocapillaries in an uncoated Al2O3 membrane: special time dependence of the transmission profile width 下载免费PDF全文
<正>This paper reports that the transmission of O6+ ions with energy of 150keV through capillaries in an uncoated Al2O3 membrane was measured,and agreements with previously reported results in general angular distribution of the transmitted ions and the transmission fractions as a function of the tilt angle well fitted to Gaussian-like functions were observed.Due to using an uncoated capillary membrane,ourψc is larger than that using a gold-coated one with a smaller value of(?),which suggests a larger equilibrium charge Q∞in our experiment.The observed special width variation with time and a larger width than that using a smaller(?) were qualitatively explained by using mean-field classical transport theory based on a classical-trajectory Monte Carlo simulation. 相似文献
4.
We study the effect of incubation period on epidemic spreading in
the Barabasi--Albert scale-free network and the Watts--Strogatz
small world network by using a
Suspectable-Incubated-Infected-Suspectable model. Our analytical
investigations show that the epidemic threshold is independent of
incubation period in both networks, which is verified by our
large-scale simulation results. We also investigate the effect of
incubation period on the epidemic dynamics in a supercritical
regime. It is found that with the increase of incubation period
Ω , a damped oscillation evolution of ρT(the
ratio of persons in incubated state) appears and the time needed to
reach a saturation value increases. Moreover, the steady value of
ρT increases and approaches to an asymptotic constant with
the value of {\it\Omega} increasing. As a result, the infected
ratio ρI decreases with the increase of Ω
according to a power law. 相似文献
5.
Xiao-Long Peng 《理论物理通讯》2022,74(3):35603
In this paper, we generalize the growing network model with preferential attachment for new links to simultaneously include aging and initial attractiveness of nodes. The network evolves with the addition of a new node per unit time, and each new node has m new links that with probability Πi are connected to nodes i already present in the network. In our model, the preferential attachment probability Πi is proportional not only to ki + A, the sum of the old node i's degree ki and its initial attractiveness A, but also to the aging factor ${\tau }_{i}^{-\alpha }$, where τi is the age of the old node i. That is, ${{\rm{\Pi }}}_{i}\propto ({k}_{i}+A){\tau }_{i}^{-\alpha }$. Based on the continuum approximation, we present a mean-field analysis that predicts the degree dynamics of the network structure. We show that depending on the aging parameter α two different network topologies can emerge. For α < 1, the network exhibits scaling behavior with a power-law degree distribution P(k) ∝ k−γ for large k where the scaling exponent γ increases with the aging parameter α and is linearly correlated with the ratio A/m. Moreover, the average degree k(ti, t) at time t for any node i that is added into the network at time ti scales as $k({t}_{i},t)\propto {t}_{i}^{-\beta }$ where 1/β is a linear function of A/m. For α > 1, such scaling behavior disappears and the degree distribution is exponential. 相似文献
6.
本文考虑带有黑洞视界和宇宙视界的Kiselev时空.研究以黑洞视界和宇宙视界为边界的系统的热力学性质.统一地给出了两个系统的热力学第一定律;在黑洞视界半径远小于宇宙视界半径的情况下,近似地计算了通过宇宙视界和黑洞视界的热能.然后,探讨Kiselev时空的物质吸积特性.在吸积能量密度正比于背景能量密度的条件下给出黑洞的吸积率,讨论了黑洞吸积率与暗能量态方程参数的关系. 相似文献
7.
The principle of the Internet evolving and the conjecture of the optimal structure of Internet 下载免费PDF全文
In this paper we will give the statistical characteristics and
general principles of an optimal structure of the Internet, which is
a scale-free network. Since the purpose of the Internet is to allow
fast and easy communication, the average path length is used to
measure the performance of the network, and the number of edges of
the network is used as a metric of its cost. Based on
this, the goal of this Internet optimization problem is to obtain
the highest performance with the lowest cost. A multi goal
optimization problem is proposed to model this problem. By using two
empirical formulas of and , we are able
to find the statistical characteristics of the optimal structure.
There is a critical power law exponent α c for the
Internet with power law degree distribution, at which the Internet
can obtain a relatively good performance with a low cost. We find
that this α c is approximately 2.1. 相似文献
8.
We investigate the pairwise entanglement and global entanglement in a
generalized Jaynes--Cummings model, which can be used to realize
Greenberger--Horne--Zeilinger (GHZ) entangled state (Zheng S B 2001
{\it Phys. Rev. Lett.} {\bf 87} 230404). Our results show that the
W-type entangled states cannot be generated based on the model. The
dependences of entanglement on Rabi frequency $\lambda$ and
dipole--dipole coupling strength ${\it \Omega}$ are given. It is
found that there exists the quantum phase transition when
$\lambda={\it \Omega}$. For typical experimental data, the critical
temperature for pairwise entanglement is on the order of
$10^{-6}$\,K. Based on these results, two strategies that overcome
decoherence are proposed. 相似文献
9.
Electron tunnelling phase time and dwell time through an associated delta potential barrier 下载免费PDF全文
The electron tunnelling phase time τP and dwell time τD through an associated delta potential barrier U(x) = ξδ(x) are calculated and both are in the order of 10^-17~10^-16s. The results show that the dependence of the phase time on the delta barrier parameter ξ can be described by the characteristic length lc = h^2/meξ and the characteristic energy Ec=meξ^2/h^2 of the delta barrier, where me is the electron mass, lc and Ec are assumed to be the effective width and height of the delta barrier with lcEc=ξ, respectively. It is found that TD reaches its maximum and τD = τp as the energy of the tunnelling electron is equal to Ec/2, i.e. as lc =λDB, λDB is de Broglie wave length of the electron. 相似文献
10.
11.
Kinetic Ising model in a time-dependent oscillating external magnetic field: effective-field theory 下载免费PDF全文
Recently,Shi et al.[2008 Phys.Lett.A 372 5922] have studied the dynamical response of the kinetic Ising model in the presence of a sinusoidal oscillating field and presented the dynamic phase diagrams by using an effective-field theory(EFT) and a mean-field theory(MFT).The MFT results are in conflict with those of the earlier work of Tom’e and de Oliveira,[1990 Phys.Rev.A 41 4251].We calculate the dynamic phase diagrams and find that our results are similar to those of the earlier work of Tom’e and de Oliveira;hence the dynamic phase diagrams calculated by Shi et al.are incomplete within both theories,except the low values of frequencies for the MFT calculation.We also investigate the influence of external field frequency(ω) and static external field amplitude(h0) for both MFT and EFT calculations.We find that the behaviour of the system strongly depends on the values of ω and h0. 相似文献
12.
A percolation study of RTS noise in deep sub-micron MOSFET by Monte Carlo simulation 总被引:2,自引:0,他引:2 下载免费PDF全文
Based on percolation theory and random telegraph signal (RTS) noise generation mechanism, a numerical model for RTS in deep submicron metal-oxide-semiconductor field-effect transistor (MOSFET) was presented, with which the dependence of Tc/Te (where Tc=capture time, Te=emission period ) on energy levels and trap depth with respect to the interface of traps can be simulated. Compared with experimental results, the simulated ones showed a good qualitative agreement. 相似文献
13.
14.
Characteristics and parameter extraction for NiGe/n-type Ge Schottky diode with variable annealing temperatures 下载免费PDF全文
Current transport mechanism in Ni-germanide/n-type Ge
Schottky diodes is investigated using current--voltage
characterisation technique with annealing temperatures from 300~\duto 500~\du. Based on the current transport model, a simple method to
extract parameters of the NiGe/Ge diode is presented by using the
$I$--$V$ characteristics. Parameters of NiGe/n-type Ge Schottky
diodes fabricated for testing in this paper are as follows: the
ideality factor $n$, the series resistance $R_{\rm s}$, the
zero-field barrier height $\phi _{\rm b0}$, the interface state
density $D_{\rm it}$, and the interfacial layer capacitance $C_{\rm
i}$. It is found that the ideality factor $n$ of the diode increases
with the increase of annealing temperature. As the temperature
increases, the interface defects from the sputtering damage and the
penetration of metallic states into the Ge energy gap are
passivated, thus improving the junction quality. However, the
undesirable crystallisations of Ni-germanide are observed together
with NiGe at a temperature higher than 400~\du. Depositing a very
thin ($\sim $1~nm) heavily Ge-doped $n^{+}$ Ge intermediate layer
can improve the NiGe film morphology significantly. 相似文献
15.
S. Carmi Z. Wu E. López S. Havlin H. Eugene Stanley 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(2):165-174
We study the transport properties of model networks such as
scale-free and Erd?s-Rényi networks as well as a real
network. We consider few possibilities for the trnasport problem.
We start by studying the conductance G between two arbitrarily
chosen nodes where each link has the same unit resistance. Our
theoretical analysis for scale-free networks predicts a broad
range of values of G, with a power-law tail distribution
$\Phi_{\rm SF}(G)\sim G^{-g_G}$
, where gG=2λ-1, and
λ is the decay exponent for the scale-free network degree
distribution. The power-law tail in ΦSF(G) leads to
large values of G, thereby significantly improving the transport
in scale-free networks, compared to Erd?s-Rényi networks
where the tail of the conductivity distribution decays
exponentially. We develop a simple physical picture of the
transport to account for the results. The other model for
transport is the max-flow model, where conductance is defined
as the number of link-independent paths between the two nodes, and
find that a similar picture holds. The effects of distance on the
value of conductance are considered for both models, and some
differences emerge. We then extend our study to the case of
multiple sources ans sinks, where the transport is defined between two
groups of nodes. We find a fundamental difference between
the two forms of flow when considering the quality of the
transport with respect to the number of sources, and find an
optimal number of sources, or users, for the max-flow case. A
qualitative (and partially quantitative) explanation is also
given. 相似文献
16.
The dependence between neutron skin thickness and neutron abrasion cross section (σnabr) for neutron-rich nuclei is investigated within the framework of the statistical abrasion ablation model. Assuming that the density distributions for proton and neutron are of Fermi-type, and adjusting the diffuseness parameter of neutron density distribution in the droplet model, we find out the good linear correlation between the neutron skin thickness and the abrasion cross section σnabr for neutron-rich nuclei. The uncertainty of neutron skin thickness determined from σnabr is very small. It is suggested that σnabr can be used as a new experimental observable to extract the neutron skin thickness for neutronrich nucleus. The scaling behaviours between neutron skin thickness and σnabr, separately, for isotopes of ^26-35Na, ^44-56Ar, ^48-60Ca, ^67-78Ni are also investigated. 相似文献
17.
Fluctuations and pseudo long range dependence in network flows: A non-stationary Poisson process model 下载免费PDF全文
In the study of complex networks (systems), the scaling phenomenon
of flow fluctuations refers to a certain power-law between the mean
flux (activity) < Fi> of the i-th node and its
variance σi as Fi ∝ <Fiα. Such scaling laws are found to be prevalent both in
natural and man-made network systems, but the understanding of their
origins still remains limited. This paper proposes a non-stationary
Poisson process model to give an analytical explanation of the
non-universal scaling phenomenon: the exponent α varies
between 1/2 and 1 depending on the size of sampling time window
and the relative strength of the external/internal driven forces of
the systems. The crossover behaviour and the relation of fluctuation
scaling with pseudo long range dependence are also accounted for by
the model. Numerical experiments show that the proposed model can
recover the multi-scaling phenomenon. 相似文献
18.
Cailong Jin Jin Lan Xuean Zhao Wenquan Sui 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(9):187
Fisher-Lee relation\hbox{$\bm{t}= {i}\bm{\Gamma}_L^{1/2}\bm{G}\bm{\Gamma}^{1/2}_R$}t=iΓL1/2GΓR1/2is a well-established tool to decode the modeinformation from Green’s function and coupling parameters. Using the Bloch eigen-modes ofthe leads, we show that the\hbox{$\bm{\Gamma}^{1/2}_{L/R}$}ΓL/R1/2term can be expressed by the Bloch eigen-mode vectorsand the wave velocities which give unambiguous algorithm of\hbox{$\bm{\Gamma}^{1/2}_{L/R}$}ΓL/R1/2in the Fish-Lee relation. Using this approach, wepresent an accurate and convenient technique to analyze all transport modes and also thedominant channels of an electronic transport system in tight-binding model. We studygraphene nanoribbon structures to demonstrate the typical application of our technique. 相似文献
19.
20.
Ru thickness-dependent interlayer coupling and ultrahigh FMR frequency in FeCoB/Ru/FeCoB sandwich trilayers 下载免费PDF全文
The antiferromagnetic (AFM) interlayer coupling effective field in a ferromagnetic/non-magnetic/ferromagnetic (FM/NM/FM) sandwich structure, as a driving force, can dramatically enhance the ferromagnetic resonance (FMR) frequency. Changing the non-magnetic spacer thickness is an effective way to control the interlayer coupling type and intensity, as well as the FMR frequency. In this study, FeCoB/Ru/FeCoB sandwich trilayers with Ru thickness ($t_{\rm Ru}$) ranging from 1 Å to 16 Å are prepared by a compositional gradient sputtering (CGS) method. It is revealed that a stress-induced anisotropy is present in the FeCoB films due to the B composition gradient in the samples. A $t_{\mathrm{Ru}}$-dependent oscillation of interlayer coupling from FM to AFM with two periods is observed. An AFM coupling occurs in a range of $2 {\rm Å} \le t_{\rm Ru} \le 8 {\rm Å}$ and over 16 $\mathrm{Å}$, while an FM coupling is present in a range of $t_{\rm Ru}< 2$ Å and $9 {\rm Å} \le t_{\rm Ru} \le 14.5 Å$. It is interesting that an ultrahigh optical mode (OM) FMR frequency in excess of 20 GHz is obtained in the sample with ${t}_{\mathrm{Ru}}= 2.5 \mathrm{Å}$ under an AFM coupling. The dynamic coupling mechanism in trilayers is simulated, and the corresponding coupling types at different values of $t_{\mathrm{Ru}}$ are verified by Layadi's rigid model. This study provides a controllable way to prepare and investigate the ultrahigh FMR films. 相似文献