共查询到20条相似文献,搜索用时 31 毫秒
1.
Recent commissioning of the Cooler Storage Ring at the Heavy Ion Research Facility in Lanzhou enabled us to conduct high-precision mass measurements at the Institute of Modern Physics in Lanzhou (IMP). In the past few years, mass measurements were performed using the CSRe-based isochronous mass spectrometry employing the fragmentation of the energetic beams of 58Ni, 78Kr, 86Kr, and 112Sn projectiles. Masses of short-lived nuclides on both sides of the stability valley were addressed. Relative mass precision of down to 10−6 ~ 10−7 is routinely achieved. The mass values were used as an input for dedicated nuclear structure and astrophysics studies, providing for instance new insights into the rp-process of nucleosynthesis in X-ray bursts. In this contribution, we briefly review the so far conducted experiments and the main achieved results, as well as outline the plans for future experiments. 相似文献
2.
In this paper,a new approach is devoted to find novel analytical and approximate solutions to the damped quadratic nonlinear Helmholtz equation(HE)in terms of the Weiersrtrass elliptic function.The exact solution for undamped HE(integrable case)and approximate/semi-analytical solution to the damped HE(non-integrable case)are given for any arbitrary initial conditions.As a special case,the necessary and sufficient condition for the integrability of the damped HE using an elementary approach is reported.In general,a new ansatz is suggested to find a semi-analytical solution to the non-integrable case in the form of Weierstrass elliptic function.In addition,the relation between the Weierstrass and Jacobian elliptic functions solutions to the integrable case will be derived in details.Also,we will make a comparison between the semi-analytical solution and the approximate numerical solutions via using Runge-Kutta fourth-order method,finite difference method,and homotopy perturbation method for the first-two approximations.Furthermore,the maximum distance errors between the approximate/semi-analytical solution and the approximate numerical solutions will be estimated.As real applications,the obtained solutions will be devoted to describe the characteristics behavior of the oscillations in RLC series circuits and in various plasma models such as electronegative complex plasma model. 相似文献
3.
Turbulence-induced changes in degree of polarization, degree of coherence and spectrum of partially coherent electromagnetic beams 下载免费PDF全文
Based on a recently formulated unified theory of coherence
and polarization, a method is described to study turbulence-induced
changes in the polarization, the coherence and the spectrum of
partially coherent electromagnetic beams on propagation. The
electromagnetic Gaussian Schell-model beam is taken as a typical
example of partially coherent electromagnetic beams, and the
closed-form expressions for the degree of polarization, the degree
of coherence and the spectrum of electromagnetic Gaussian
Schell-model beams propagating through atmospheric turbulence are
derived in the quadratic approximation of Rytov's phase structure
function. Some interesting results are obtained, which are
illustrated by numerical examples and are explained in physics. 相似文献
4.
Two mutually conjugated tripartite entangled states and their fractional Fourier transformation kernel 下载免费PDF全文
We newly construct two mutually-conjugate tripartite entangled state representations,based on which we propose the formulation of three-mode entangled fractional Fourier transformation(EFFT) and derive the transformation kernel.The EFFT’s additivity property is proved and the eigenmode of EFFT is derived.As an application,we calculate the EFFT of the three-mode squeezed vacuum state. 相似文献
5.
Upper bound for the time derivative of entropy for a stochastic dynamical system with double singularities driven by non-Gaussian noise 下载免费PDF全文
A stochastic dynamical system with double singularities
driven by non-Gaussian noise is investigated. The Fokker--Plank
equation of the system is obtained through the path-integral
approach and the method of transformation. Based on the definition
of Shannon's information entropy and the Schwartz inequality
principle, the upper bound for the time derivative of entropy is
calculated both in the absence and in the presence of
non-equilibrium constraint. The present calculations can be used to
interpret the effects of the system dissipative parameter, the
system singularity strength parameter, the noise correlation time
and the noise deviation parameter on the upper bound. 相似文献
6.
<正>With the development of the compressive sensing theory,the image reconstruction from the projections viewed in limited angles is one of the hot problems in the research of computed tomography technology.This paper develops an iterative algorithm for image reconstruction,which can fit most cases.This method gives an image reconstruction flow with the difference image vector,which is based on the concept that the difference image vector between the reconstructed and the reference image is sparse enough.Then the l_2-norm minimization method is used to reconstruct the difference vector to recover the image for flat subjects in limited angles.The algorithm has been tested with a thin planar phantom and a real object in limited-view projection data.Moreover,all the studies showed the satisfactory results in accuracy at a rather high reconstruction speed. 相似文献
7.
In 1949, Tolman found the relation between the surface tension and Tolman length, which determines the dimensional effect of the surface tension. Tolman length is the difference between the equimolar surface and the surface of tension. In recent years, the magnitude, expression, and sign of the Tolman length remain an open question. An incompressible and homogeneous liquid droplet model is proposed and the approximate expression and sign for Tolman length are derived in this paper. We obtain the relation between Tolman length and the radius of the surface of tension(Rs) and found that they increase with the Rs decreasing. The Tolman length of plane surface tends to zero. Taking argon for example, molecular dynamics simulation is carried out by using the Lennard–Jones(LJ) potential between atoms at a temperature of 90 K. Five simulated systems are used, with numbers of argon atoms being 10140, 10935, 11760, 13500, and 15360, respectively. By methods of theoretical study and molecular dynamics simulation, we find that the calculated value of Tolman length is more than zero, and it decreases as the size is increased among the whole size range. The value of surface tension increases with the radius of the surface of tension increasing, which is consistent with Tolman’s theory. These conclusions are significant for studying the size dependence of the surface tension. 相似文献
8.
Second harmonic magnetoacoustic responses of magnetic nanoparticles in magnetoacoustic tomography with magnetic induction 下载免费PDF全文
Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The linear and nonlinear magnetoacoustic responses determined by the magnetic properties of MNPs have attracted more and more attention in biomedical engineering. By considering the relaxation time of MNPs, we derive the formulae of second harmonic magnetoacoustic responses(2H-MARs) for a cylindrical MNP solution model based on the mechanical oscillations of MNPs in magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that only the second harmonic magnetoacoustic oscillations can be generated by MNPs under an alternating magnetic excitation. The acoustic pressure of the 2H-MAR is proportional to the square of the magnetic field intensity and exhibits a linear increase with the concentration of MNPs. Numerical simulations of the 2H-MAR are confirmed by the experimental measurements for various magnetic field intensities and solution concentrations using a laser vibrometer. The favorable results demonstrate the feasibility of the harmonic measurements without the fundamental interference of the electromagnetic excitation, and suggest a new harmonic imaging strategy of MAT-MI for MNPs with enhanced spatial resolution and improved signal-to-noise ratio in biomedical applications. 相似文献
9.
X-ray absorption near the edge structure and x-ray photoelectron spectroscopy studies on pyrite prepared by thermally sulfurizing iron films 下载免费PDF全文
This paper reports how pyrite films were prepared by thermal
sulfurization of magnetron sputtered iron films and characterized by
x-ray absorption near edge structure spectra and x-ray photoelectron
spectroscopy on a 4B9B beam line at the Beijing Synchrotron Radiation
Facility. The band gap of the pyrite agrees well with the optical
band gap obtained by a spectrophotometer. The octahedral symmetry of
pyrite leads to the splitting of the d orbit into t_{\rm 2g} and
e_{\rm g} levels. The high spin and low spin states were analysed
through the difference of electron exchange interaction and the orbital
crystal field. Only when the crystal field splitting is higher than
1.5 eV, the two weak peaks above the white lines can appear, and this
was approved by experiments in the present work. 相似文献
10.
Travelling solitary wave solutions for the generalized Burgers--Huxley equation with nonlinear terms of any order 下载免费PDF全文
In this paper, the travelling wave solutions for the generalized
Burgers--Huxley equation with nonlinear terms of any order are
studied. By using the first integral method, which is based on the
divisor theorem, some exact explicit travelling solitary wave
solutions for the above equation are obtained. As a result, some
minor errors and some known results in the previousl literature
are clarified and improved. 相似文献
11.
Robust stability analysis for Markovian jumping stochastic neural networks with mode-dependent time-varying interval delay and multiplicative noise 下载免费PDF全文
This paper is concerned with the problem of robust stability for a
class of Markovian jumping stochastic neural networks (MJSNNs)
subject to mode-dependent time-varying interval delay and
state-multiplicative noise. Based on the Lyapunov--Krasovskii functional
and a stochastic analysis approach, some new delay-dependent
sufficient conditions are obtained in the linear matrix inequality
(LMI) format such that delayed MJSNNs are globally asymptotically
stable in the mean-square sense for all admissible uncertainties. An
important feature of the results is that the stability criteria are
dependent on not only the lower bound and upper bound of delay for all
modes but also the covariance matrix consisting of the correlation
coefficient. Numerical examples are given to illustrate the
effectiveness. 相似文献
12.
An improved boundary element-free method (IBEFM) for two-dimensional potential problems 总被引:1,自引:0,他引:1 下载免费PDF全文
The interpolating moving least-squares (IMLS) method is discussed
first in this paper. And the formulae of the IMLS method obtained by
Lancaster are revised. Then on the basis of the boundary
element-free method (BEFM), combining the boundary integral equation
(BIE) method with the IMLS method, the improved boundary
element-free method (IBEFM) for two-dimensional potential problems
is presented, and the corresponding formulae of the IBEFM are
obtained. In the BEFM, boundary conditions are applied directly, but
the shape function in the MLS does not satisfy the property of
the Kronecker δ function. This is a problem of the BEFM, and
must be solved theoretically. In the IMLS method, when the shape function
satisfies the property of the Kronecker δ function, then the
boundary conditions, in the meshless method based on the IMLS
method, can be applied directly. Then the IBEFM, based on the IMLS
method, is a direct meshless boundary integral equation method in
which the basic unknown quantity is the real solution of the nodal
variables, and the boundary conditions can be applied directly and
easily, thus it gives a greater computational precision. Some
numerical examples are presented to demonstrate the method. 相似文献
13.
Random-injection-based two-channel chaos with enhanced bandwidth and suppressed time-delay signature by mutually coupled lasers: Proposal and numerical analysis 下载免费PDF全文
Simultaneous bandwidth(BW) enhancement and time-delay signature(TDS) suppression of chaotic lasing over a wide range of parameters by mutually coupled semiconductor lasers(MCSLs) with random optical injection are proposed and numerically investigated. The influences of system parameters on TDS suppression(characterized by autocorrelation function(ACF) and permutation entropy(PE) around characteristic time) and chaos BW are investigated. The results show that, with the increasing bias current, the ranges of parameters(detuning and injection strength) for the larger BW(> 20 GHz) are broadened considerably, while the parameter range for optimized TDS(< 0.1) is not shrunk obviously.Under optimized parameters, the system can simultaneously achieve two chaos outputs with enhanced BW(> 20 GHz)and perfect TDS suppression. In addition, the system can generate two-channel high-speed truly physical random number sequences at 200 Gbits/s for each channel. 相似文献
14.
Brane world black holes in teleparallel theory equivalent to general relativity and their Killing vectors, energy, momentum and angular momentum 下载免费PDF全文
Gamal G.L. Nashed 《中国物理 B》2010,19(2):20401-020401
The energy--momentum tensor, which is coordinate-independent, is
used to calculate energy, momentum and angular momentum of two
different tetrad fields. Although, the two tetrad fields reproduce
the same space--time their energies are different. Therefore, a
regularized expression of the gravitational energy--momentum tensor
of the teleparallel equivalent of general relativity (TEGR), is
used to make the energies of the two tetrad fields equal. The
definition of the gravitational energy--momentum is used to
investigate the energy within the external event horizon. The
components of angular momentum associated with these space--times
are calculated. In spite of using a static space--time, we get
a non-zero component of angular momentum! Therefore, we derive
the Killing vectors associated with these space--times using the
definition of the Lie derivative of a second rank tensor in the
framework of the TEGR to make the picture more clear. 相似文献
15.
Fractional differential equations of motion in terms of combined Riemann—Liouville derivatives 下载免费PDF全文
In this paper,we focus on studying the fractional variational principle and the differential equations of motion for a fractional mechanical system.A combined Riemann-Liouville fractional derivative operator is defined,and a fractional Hamilton principle under this definition is established.The fractional Lagrange equations and the fractional Hamilton canonical equations are derived from the fractional Hamilton principle.A number of special cases are given,showing the universality of our conclusions.At the end of the paper,an example is given to illustrate the application of the results. 相似文献
16.
The formation of macrostep during high-temperature phase of barium meta-borate (α-BaB 2 O 4) single crystal growth has been investigated by both optical in-situ observation system and atomic force microscopy (AFM).The insitu observation results demonstrate that the critical linear size of growing facet exceeding the size that the macrostep generates is significantly anisotropic.The critical linear sizes are around 280 μm and 620 μm for {1010} and {1010} planes,respectively.AFM study illustrates that macrostep train with a height of 150 nm~200 nm is one typical morphological feature of the as-grown crystal surface.The riser of each macrostep consists of several straight and parallel sub-steps,indicating the occurrence of step bunching.Additionally,triangular sub-steps with heights of several nanometers on the treads of the macrosteps are found to be another typical feature of surface morphology,which implies a microscopically competitive bunching of sub-steps between various crystallographic orientations. 相似文献
17.
In this paper, global synchronization of general delayed complex networks with stochastic disturbances, which is a zero-mean real scalar Wiener process, is investigated. The networks under consideration are continuous-time networks with time-varying delay. Based on the stochastic Lyapunov stability theory, It?'s differential rule and the linear matrix inequality (LMI) optimization technique, several delay-dependent synchronous criteria are established, which guarantee the asymptotical mean-square synchronization of drive networks and response networks with stochastic disturbances. The criteria are expressed in terms of LMI, which can be easily solved using the Matlab LMI Control Toolbox. Finally, two examples show the effectiveness and feasibility of the proposed synchronous conditions. 相似文献
18.
LISA and Taiji are expected to form a space-based gravitational-wave(GW)detection network in the future.In this work,we make a forecast for the cosmological parameter estimation with the standard siren observation from the LISA-Taiji network.We simulate the standard siren data based on a scenario with configuration angle of 40°between LISA and Taiji.Three models for the population of massive black hole binary(MBHB),i.e.,popⅢ,Q3d,and Q3nod,are considered to predict the events of MBHB mergers.We find that,based on the LISA-Taiji network,the number of electromagnetic(EM)counterparts detected is almost doubled compared with the case of single Taiji mission.Therefore,the LISA-Taiji network’s standard siren observation could provide much tighter constraints on cosmological parameters.For example,solely using the standard sirens from the LISA-Taiji network,the constraint precision of H;could reach 1.3%.Moreover,combined with the CMB data,the GW-EM observation based on the LISA-Taiji network could also tightly constrain the equation of state of dark energy,e.g.,the constraint precision of w reaches about 4%,which is comparable with the result of CMB+BAO+SN.It is concluded that the GW standard sirens from the LISA-Taiji network will become a useful cosmological probe in understanding the nature of dark energy in the future. 相似文献
19.
The energy content of the charged-Kerr(CK)spacetime surrounded by dark energy(DE)is investigated using approximate Lie symmetry methods for the differential equations.For this,we consider three different DE scenarios:cosmological constant with an equation of state parameter$ωq=-2/3,quintessence DE with an equation of state parameterωc=-1,and a frustrated network of cosmic strings with an equation of state parameterωn=-1/3.To study the gravitational energy of the CK black hole surrounded by the DE,we explore the symmetries of the 2nd-order perturbed geodesic equations.It is noticed,for all the values ofω,the exact symmetries are recovered as 2nd-order approximate trivial symmetries.These trivial approximate symmetries give the rescaling of arc length parameter s in this spacetime which indicates that the energy in the underlying spacetime has to be rescaled by a factor that depends on the black hole parameters and the DE parameter.This rescaling factor is compared with the factor of the CK spacetime found in[Hussain et al.Gen.Relativ.Gravit.(2009)]and the effects of the DE on it are discussed.It is observed that for all the three values of the equation of state parameterω,the effect of DE results in decreased energy content of the black hole spacetime,regardless of values of the charge Q,spin a and the DE parameterα.This reduction in the energy content due to the involvement of the DE favours the idea of mass reduction of black holes by accretion of DE given by[Babichev et al.Phys.Rev.Lett.(2004)]. 相似文献
20.
We discuss quantum fluctuation in excited states(named thermo number states) of mesoscopic LC circuits at a finite temperature.By introducing the coherent thermo state into the thermo field dynamics pioneered by Umezawa and using the natural representation of thermo squeezing operator we can concisely derive the fluctuation.The result shows that the noise becomes larger when either temperature or the excitation number increases. 相似文献