A universal estimation formula for the average path length of scale
free networks is given in this paper. Different from other
estimation formulas, most of which use the size of network, $N$, as
the only parameter, two parameters including $N$ and a second
parameter $\alpha $ are included in our formula. The parameter
$\alpha $ is the power-law exponent, which represents the local
connectivity property of a network. Because of this, the formula
captures an important property that the local connectivity property
at a microscopic level can determine the global connectivity of the
whole network. The use of this new parameter distinguishes this
approach from the other estimation formulas, and makes it a
universal estimation formula, which can be applied to all types of
scale-free networks. The conclusion is made that the small world
feature is a derivative feature of a scale free network. If a
network follows the power-law degree distribution, it must be a
small world network. The power-law degree distribution property,
while making the network economical, preserves the efficiency
through this small world property when the network is scaled up. In
other words, a real scale-free network is scaled at a relatively
small cost and a relatively high efficiency, and that is the
desirable result of self-organization optimization.

$2N$ line-soliton solutions of the (2+1)-dimensional
Kadomtsev--Petviashvili equation can be presented by resorting to
the Hirota bilinear method. By extending the real parameters into
complex parameters, this paper obtains $N$ periodic-soliton
solutions of the (2+1)-dimensional Kadomtsev--Petviashvili equation
from the $2N$ line-soliton solutions.

The thermal entanglement and teleportation of a thermally mixed
entangled state of a two-qubit Heisenberg $XXX$ chain under the
Dzyaloshinski--Moriya (DM) anisotropic antisymmetric interaction
through a noisy quantum channel given by a Werner state is
investigated. The dependences of the thermal entanglement of the
teleported state on the DM coupling constant, the temperature and
the entanglement of the noisy quantum channel are studied in detail
for both the ferromagnetic and the antiferromagnetic cases. The
result shows that a minimum entanglement of the noisy quantum
channel must be provided in order to realize the entanglement
teleportation. The values of fidelity of the teleported state are
also studied for these two cases. It is found that under certain
conditions, we can transfer an initial state with a better fidelity
than that for any classical communication protocol.

This paper presents a simple way for an eavesdropper to eavesdrop
freely the secret message in the experimental realization of quantum
communication protocol proposed by Beige {\em et al} (2002 \emph{Acta
Phys. Pol.} A \textbf{101} 357). Moreover, it introduces an efficient
quantum secure communication protocol based on a publicly known key
with decoy photons and two biased bases by modifying the original
protocol. The total efficiency of this new protocol is double that
of the original one. With a low noise quantum channel, this protocol
can be used for transmitting a secret message. At present, this
protocol is good for generating a private key efficiently.

This paper uses an elegant mathematical method to calculate the
orbital effects in the axisymmetric field created by the spinning
mass with electric charge and a large number of magnetic monopoles.
In comparison with that in the Reissner--Nordstr\"om (R--N) field,
the correction terms caused by the spinning mass decrease the
advanced effect as the revolution direction of the test particle
coincides with that of the Kerr field, however, the correction terms
caused by the spinning charged mass increase the advance effect as
the revolution direction of the test particle coincides with that of
the Kerr--Newman--Kasnya (KNK) field. Generalizing the effect in the
axisymmetric field, it obtains interesting results by discussing the
parameters of the celestial body, these parameters provide a feasible
experimental verification of the general relativity.

DNA is a nucleic acid molecule with double-helical structures that
are special symmetrical structures attracting great attention of
numerous researchers. The super-long elastic slender rod, an
important structural model of DNA and other long-train molecules, is
a useful tool in analysing the symmetrical properties and the
stabilities of DNA. This paper studies the structural properties of a
super-long elastic slender rod as a structural model of DNA by using
Kirchhoff's analogue technique and presents the Noether symmetries of
the model by using the method of infinitesimal transformation. Based
on Kirchhoff's analogue it analyses the generalized Hamilton
canonical equations. The infinitesimal transformations with respect
to the radial coordinate, the generalized coordinates, and the
quasi-momenta of the model are introduced. The Noether symmetries and
conserved quantities of the model are obtained.

From the macroscopic viewpoint for describing the acceleration
behaviour of drivers, a weighted probabilistic cellular automaton
model (the WP model, for short) is proposed by introducing a kind of
random acceleration probabilistic distribution function. The
fundamental diagrams, the spatiotemporal patterns, are analysed in
detail. It is shown that the presented model leads to the results
consistent with the empirical data rather well, nonlinear
flow--density relationship existing in lower density regions, and a
new kind of traffic phenomenon called neo-synchronized flow.
Furthermore, we give the criterion for distinguishing the high-speed
and low-speed neo-synchronized flows and clarify the mechanism of
this kind of traffic phenomenon. In addition, the result that the
time evolution of distribution of headways is displayed as a normal
distribution further validates the reasonability of the
neo-synchronized flow. These findings suggest that the diversity and
the randomicity of drivers and vehicles have indeed a remarkable
effect on traffic dynamics.

This paper presents a novel approach to extract the periodic signals
masked by a chaotic carrier. It verifies that the driven Duffing
oscillator is immune to the chaotic carrier and sensitive to certain
periodic signals. A preliminary detection scenario illustrates that
the frequency and amplitude of the hidden sine wave signal can be
extracted from the chaotic carrier by numerical simulation. The
obtained results indicate that the hidden messages in chaotic secure
communication can be eavesdropped utilizing Duffing oscillators.

A whole impulsive control scheme of nonlinear systems with
time-varying delays, which is an extension for impulsive control of
nonlinear systems without time delay, is presented in this paper.
Utilizing the Lyapunov functions and the impulsive-type comparison
principles, we establish a series of different conditions under
which impulsively controlled nonlinear systems with time-varying
delays are asymptotically stable. Then we estimate upper bounds of
impulse interval and time-varying delays for asymptotically stable
control. Finally a numerical example is given to illustrate the
effectiveness of the method.

The design of an efficient one-way hash function with good
performance is a hot spot in modern cryptography researches. In this
paper, a hash function construction method based on cell neural
network with hyper-chaos characteristics is proposed. First, the
chaos sequence is gotten by iterating cellular neural network with
Runge--Kutta algorithm, and then the chaos sequence is iterated with
the message. The hash code is obtained through the corresponding
transform of the latter chaos sequence. Simulation and analysis
demonstrate that the new method has the merit of convenience, high
sensitivity to initial values, good hash performance, especially the
strong stability.

In this paper we report a kind of fast-scale instability occurring
in the single-ended primary inductance converter (SEPIC) power
factor pre-regulator, which is designed to operate in discontinuous
conduction mode. Main results are given by exact cycle-by-cycle
computer simulations as well as theoretical analysis. It is found
that the instability phenomenon manifests itself as a fast-scale
bifurcation at the switching period, which implies the occurrence of
border collision bifurcation, or is related to the transition of the
regular operating mode of the SEPIC. According to the theoretical
analysis and simulation results, the effects of parameters on system
stability, and the locations of the bifurcation points are
confirmed. Moreover, the effects of such an instability on power
factor and switching stress are also discussed. Finally, the
occurrence of the asymmetric bifurcation locations is investigated.
The results show that this work provides a convenient means of
predicting stability boundaries which can facilitate the selection
of the practical parameters.

We propose an impulsive hybrid control method to control the
period-doubling bifurcations and stabilize unstable periodic orbits
embedded in a chaotic attractor of a small-world network. Simulation
results show that the bifurcations can be delayed or completely
eliminated. A periodic orbit of the system can be controlled to any
desired periodic orbit by using this method.

This paper is involved with the adaptive control and synchronization
problems for an uncertain new hyperchaotic Lorenz system. Based on
the Lyapunov stability theory, the adaptive control law is derived
such that the trajectory of hyperchaotic Lorenz system with unknown
parameters can be globally stabilized to an unstable equilibrium
point of the uncontrolled system. Furthermore, an adaptive control
approach is presented to the synchronizations between two identical
hyperchaotic systems, particularly between two different uncertain
hyperchaotic systems. Numerical simulations show the effectiveness
of the presented method.

Local bifurcation phenomena in a four-dimensional continuous
hyperchaotic system, which has rich and complex dynamical
behaviours, are analysed. The local bifurcations of the system are
investigated by utilizing the bifurcation theory and the centre
manifold theorem, and thus the conditions of the existence of
pitchfork bifurcation and Hopf bifurcation are derived in detail.
Numerical simulations are presented to verify the theoretical
analysis, and they show some interesting dynamics, including stable
periodic orbits emerging from the new fixed points generated by
pitchfork bifurcation, coexistence of a stable limit cycle and a
chaotic attractor, as well as chaos within quite a wide parameter
region.

This paper studies the Kapchinsky--Vladimirsky (K--V) beam through a
triangle periodic-focusing magnetic field by using the particle-core
model. The beam halo-chaos is found, and an idea of Gauss function
controller is proposed based on the strategy of controlling the
halo-chaos. It performs multiparticle simulation to control the halo
by using the Gauss function control method. The numerical results
show that the halo-chaos and its regeneration can be eliminated
effectively, and that the radial particle density is uniform at the
centre of the beam as long as the control method and appropriate
parameter are chosen.

In this paper, the evolution of the pattern transition induced by
the vortical electric field (VEF) is investigated. Firstly, a scheme
is suggested to generate the VEF by changing the spatial magnetic
field. Secondly, the VEF is imposed on the whole medium, and the
evolutions of the spiral wave and the spatiotemporal chaos are
investigated by using the numerical simulation. The result confirms
that the drift and the breakup of the spiral wave and the new
net-like pattern are observed when different polarized fields are
imposed on the whole medium respectively. Finally, the pattern
transition induced by the polarized field is discussed
theoretically.

In this paper, we give a controlled two-degree-of-freedom (TDOF)
vibro-impact system based on the damping control law, and then
investigate the dynamical behaviour of this system. According to
numerical simulation, we find that this control scheme can suppress
chaos to periodic orbit successfully. Furthermore, the feasibility
and the robustness of the controller are confirmed, separately. We
also find that this scheme cannot only suppress chaos, but also
generate chaos in this system.

This paper derives and uses the recurrence expressions for the power
spectra of diffracted pulsed Hermite--Gaussian (HG) beams in
dispersive media to study the spectral anomalies of pulsed HG beams
in the far field. Numerical results are given to illustrate the
dependence of spectral switches on the pulse parameters, truncation
parameter and dispersive property of the medium. The potential
application of spectral anomalies of ultrashort pulsed beams in
information encoding and transmission is discussed.

The transverse momentum distribution and the transverse mass
distribution of charged hadrons produced in nucleus--nucleus
collisions at high energies are described by using a two-cylinder
model. The results calculated by the model are compared and found to
be in agreement with the experimental data of the STAR and E895
Collaborations, measured in Au--Au collisions at the relativistic
heavy ion collider (RHIC) and alternating-gradient synchrotron (AGS)
energies, respectively. In the energy range concerned, the
excitation degree of emission source close to the central axis of
cylinders increases obviously with the collision centrality and
incident energy increasing, but it does not show any obvious change
with the increase of the (pseudo)rapidity in central collisions. The
excitation degree of emission source close to the side-surface of
cylinders does not show any obvious change with the collision
centrality, the (pseudo)rapidity, and the incident energy
increasing.

On the basis of a rigorous field theory, two different physical
models of attenuator and sever have been proposed. One is named High
attenuation (HATT) model in which both attenuator and sever are
considered as a unified attenuator, but the sever is regarded as an
area of very high loss; the other is called Sever and attenuator
(SATT) model in which the sever is modelled as a drift area in which
the electric and magnetic fields both vanish. A complex function is
derived and potential sinking effect is also considered. Thus, a set
of more practical self-consistent equations of nonlinear beam--wave
interaction is formulated. Simulations are carried out under the
conditions of the two different physical models, and the simulation
results are compared with the experimental data. The results show
that in the case of single signal drive, the unknown second harmonic
should be included for predicting the saturated output power. It is
also evident that the SATT model and the HATT model predict the same
physical nature, whereas the results predicted by the HATT model are
much closer to the experimental data than those obtained from the
SATT model. Therefore, these results provide a strong theoretical
basis for designing broadband and high gain helix travelling wave
tubes.

Electromagnetic scattering from a rough surface of layered medium is
investigated, and the formulae of the scattering coefficients for
different polarizations are derived using the small perturbation
method. A rough surface with exponential correlation function is
presented for describing a rough soil surface of layered medium, the
formula of its scattering coefficient is derived by considering the
spectrum of the rough surface with exponential correlation function;
the curves of the bistatic scattering coefficient of HH polarization
with variation of the scattering angle are obtained by numerical
calculation. The influence of the permittivity of layered medium,
the mean layer thickness of intermediate medium, the roughness
surface parameters and the frequency of the incident wave on the
bistatic scattering coefficient is discussed. Numerical results show
that the influence of the permittivity of layered medium, the mean
layer thickness of intermediate medium, the rms and the correlation
length of the rough surface, and the frequency of the incident wave
on the bistatic scattering coefficient is very complex.

The use of an attenuated total reflection-coupling mode of prism
coated with metal film to excite the interference of the surface
plasmon polaritons (SPPs) was proposed for periodic patterning with
a resolution of subwavelength scale. High intensity of electric
field can be obtained because of the coupling between SPPs and
evanescence under a resonance condition, which can reduce exposure
time and improve contrast. In this paper, several critical
parameters for maskless surface plasmon resonant lithography are
described, and the preliminary simulation based on a finite
difference time-domain technique agrees well with the theoretical
analysis, which demonstrates this scheme and provides the
theoretical basis for further experiments.

The refraction of rays in the Savart polariscope is different from
the isotropic medium. We have analysed and discussed the refraction
of rays in the Savart polariscope on the basis of the Snell law. The
refraction formulae of the extraordinary rays and ordinary rays were
derived. Results obtained may provide theoretical and practical
guide lines for studying, developing and engineering of polarization
interference imaging spectrometer.

Using two typical types of polarization controller, this paper
analyses theoretically and experimentally the fact that it is
necessary to adjust at least three instead of two waveplates in
order to transform any state of polarization to any other output
covering the entire Poincar\'{e} sphere. The experimental results
are exactly in accordance with the theory discussed in this paper.
It has corrected the conventional and inaccurate point of view that
two waveplates of a polarization controller are adequate to complete
the transformation of state of polarization.

Following the theoretical protocol described by Fortescue and Lo
[Fortescue B and Lo H K 2007 {\it Phys. Rev. Lett.} {\bf 98}
260501], we present a scheme in which one can distill maximally
entangled bi-partite states from a tri-partite $W$ state with cavity
QED. Our scheme enables the concrete physical system to realize its
protocol. In our scheme, the rate distillation also asymptotically
approaches one. Based on the present cavity QED techniques, we
discuss the experimental feasibility.

We investigate the Ne-like Cr x-ray laser at $28.6\,\mathrm{nm}$ by
using a modified 1D lagrangian hydrodynamic code MED103 coupled with
an atomic physics data package and a 2D ray tracing code as a
post-processor. The laser pumping configuration includes two
prepulses and one main pulse. The first prepulse normally irradiates
the target, while the second prepulse and the main pulse irradiate
the target at grazing-incident angles. We predict that saturation
can be achieved for the Ne-like Cr x-ray lasers with a total pumping
energy of $125\,\mathrm{mJ}$. Good beam qualities with no deflecting
angle and a small divergence angle of $5\,\mathrm{mrad}$ are
observed.

The population transfer in a ladder-type atomic system driven by
linearly polarized sech-shape femtosecond laser pulses is
investigated by numerically solving Schr\"{o}dinger equation without
including the rotating wave approximation (RWA). It is shown that
population transfer is mainly determined by the Rabi frequency
(strength) of the driving laser field and the chirp rate, and that
the ratio of the dipole moments and the pulse width also have a
prominent effect on the population transfer. By choosing appropriate
values of the above parameters, complete population transfer can be
realized.

From the study of the dynamics for the ring-like soliton clusters,
we find that there exists a critical value of the ring radius,
$d_{\rm cr}$, for the stationary rotation of the clusters with
respect to the beam centre even in the presence of the relatively
strong noise, and that the soliton clusters will not rotate but only
undergo periodic collisions in the form of simple harmonic
oscillator if the ring radius is large enough. We also show that the
direction of the rotation can be opposite to the direction of phase
gradient when the relative phase difference is within the domain
$0<|\theta|<\pi$, while along the direction of phase gradient when
the relative phase difference is within the domain
$\pi<|\theta|<2\pi$.

This paper investigates the third-order nonlinear optical properties
of two azo-nickel chelate compounds by the optical Kerr gate method
at 830\,nm wavelength with pulse duration of 120\,fs. Both of the two
compounds exhibited large third-order optical nonlinearity. The
second-order hyperpolarizability, $\gamma$, of Compound 1 is of
$1.0\times 10^{ - 31}$\,esu. Due to the charge transfer, the $\gamma$
of Compound 2 with electron donor and acceptor group is
$4.9\times10^{ - 31}$\,esu, which is a four-time enhancement in
comparison with Compound 1. The absorption spectra show that the
electron push--pull effect, which induces intramolecular charge
transfer, leads to the increased optical nonlinearity.

This paper investigates the temporal behaviour of open-circuit bright
photovoltaic spatial solitons by using numerical techniques. It shows
that when the intensity ratio of the soliton, the ratio between the
soliton peak intensity and the dark irradiance, is small, the
quasi-steady-state soliton width decreases monotonically with the
increase of $\tau $, where $\tau $ is the parameter correlated with
the time, that when the intensity ratio of the soliton is big, the
quasi-steady-state soliton width decreases with the increase of $\tau
$ and then increases with $\tau $, and that the formation time of the
steady-state solitons is not correlated with the intensity ratio of
the soliton. It finds that the local nonlinear effect increases with
the photovoltaic field, which behaves as that the width of soliton
beams is small and the self-focusing quasi-period is short. On the
other hand, we also discuss that both the time and the temperature
have an effect on the beam bending.

We take a finite dielectric photonic crystal as a homogeneous slab
and have extracted the effective parameters. Our systematic study
shows that the effective permittivity or permeability of dielectric
photonic crystal is negative within a band gap region. This means
that the band gap might act as $\varepsilon$-negative materials
(ENMs) with $\varepsilon <0$ and $\mu >0$, or $\mu$-negative
materials (MNMs) with $\varepsilon >0$ and $\mu <0$. Moreover the
effective parameters sensitively rely on size, surface termination,
symmetry, etc. The effective parameters can be used to design full
transmission tunnelling modes and amplify evanescent wave. Several
cases are studied and the results show that dielectric photonic band
gap can indeed mimic a single negative material (ENM or MNM) under
some restrictions.

In this paper a compact polarization beam splitter based on a
deformed photonic crystal directional coupler is designed and
simulated. The transverse-electric (TE) guided mode and
transverse-magnetic (TM) guided mode are split due to different
guiding mechanisms. The effect of the shape deformation of the air
holes on the coupler is studied. It discovered that the coupling
strength of the coupled waveguides is strongly enhanced by
introducing elliptical airholes, which reduce the device length to
less than 18.5$\mu$m. A finite-difference time-domain simulation is
performed to evaluate the performance of the device, and the
extinction ratios for both TE and TM polarized light are higher than
20\,dB.

This paper presents a novel scheme to monolithically integrate an
evanescently-coupled uni-travelling carrier photodiode with a planar
short multimode waveguide structure and a large optical cavity
electroabsorption modulator based on a multimode waveguide structure.
By simulation, both electroabsorption modulator and photodiode show
excellent optical performances. The device can be fabricated with
conventional photolithography, reactive ion etching, and chemical wet
etching.

A high-performance microring resonator in a silicon-on-insulator rib
waveguide is realized by using the electron beam lithography
followed by inductively coupled plasma etching. The design and the
experimental realization of this device are presented in detail. In
addition to improving relevant processes to minimize propagation
loss, the coupling efficiency between the ring and the bus is
carefully chosen to approach a critical coupling for high
performance operating. We have measured a quality factor of 21,200
and an extinction ratio of 12.5dB at a resonant wavelength of
1549.32nm. Meanwhile, a low propagation loss of 0.89dB/mm in a
curved waveguide with a bending radius of 40$\mu $m is demonstrated
as well.

A tunable plasmonic waveguide via gold nanoshells immerged in a
silica base is proposed and simulated by using the finite difference
time-domain (FDTD) method. For waveguides based on near-field
coupling, transmission frequencies can be tuned in a wide region from
660 to 900\,nm in wavelength by varying shell thicknesses. After
exploring the steady distributions of electric fields in these
waveguides, we find that their decay lengths are about
5.948--12.83\,dB/1000\,nm, which is superior to the decay length
(8.947\,dB/1000\,nm) of a gold nanosphere plasmonic waveguide. These
excellent tunability and transmittability are mainly due to the
unique hollow structure. These gold nanoshell waveguides should be
fabricated in laboratory.

Comprehensive numerical and experimental analyses of the effect of
viscosity on cavitation oscillations are performed. This numerical
approach is based on the Rayleigh--Plesset equation. The model
predictions are compared with experimental results obtained by using
a fibre-optic diagnostic technique based on optical beam deflection
(OBD). The maximum and minimum bubble radii as well as the
oscillation times for each oscillation cycle are determined according
to the characteristic signals. It is observed that the increasing of
viscosity decreases the maximum bubble radii but increases the
minimum bubble radii and the oscillation time. These experimental
results are consistent with numerical results.

We have been using the method of tube-arrest as a means of producing
transient single cavitation bubble. In the present paper we seek to
comprehend the mechanism of production and inquire into the structure
of the {\em ab initio} pressure field in the arrested liquid column.
The generated pressure wave is shown by combining the theoretical
analysis with the experimental observation to be a slightly varied
version of water hammer. With relatively clean liquid, the magnitude
of the tension peak generating the TSB is likely to reach of several
millions Pa. It is also shown that the so generated cavitation bubble
originating from the gas-containing bulk liquid is in `violent'
motion.

The general expressions of the average dissipative and dipole forces
acting on a $\Lambda $-configuration three-level atom in an
arbitrary light field are derived by means of the optical Bloch
equations based on the atomic density matrix elements, and the
general properties of the average dissipative and dipole forces on a
three-level atom in the linearly-polarized high-order Bessel beams
(HBBs) are analysed. We find a resonant property (with two resonant
peaks) of the dissipative force and a non-resonant property (with
two pairs of non-resonant peaks) of the dipole force on the
three-level atom, which are completely different from those on the
two-level atom. Meanwhile we find a saturation effect of the average
dissipative force in the HBB, which comes from the saturation of the
upper-level population. Our study shows that the general expressions
of the average dissipative and dipole forces on the three-level atom
will be simplified to those of the two-level atom under the
approximation of large detuning. Finally, we study the axial and
azimuthal Doppler cooling of atoms in 1D optical molasses composed
of two counter-propagating HBBs and discuss the azimuthal influence
of the HBB on the Doppler cooling limit. We also find that the
Doppler limit of atoms in the molasses HBB is slightly below the
conventional Doppler limit of ${\hbar \Ga} /({2k_{\rm B}})$ due to
the orbital angular momentum $l\hbar $ of the HBB.

The lowest-energy structures and the electronic properties of
Cd$_{n}$S$_{n}$ ($n=1-8$) clusters have been studied by using
density-functional theory simulating package DMol$^{3}$ in the
generalized gradient approximation (GGA). The ring-like structures
are the lowest-energy configurations for $n=2, 3$ and the
three-dimensional spheroid configurations for $n=4-8$. The
three-dimensional structures may be considered as being built from
the Cd$_{2}$S$_{2}$ and Cd$_{3}$S$_{3}$ rings. Compared to the
previous reports, we have found the more stable structures for
Cd$_{n}$S$_{n}$($n=7,8$). Calculations show that the magic numbers
of Cd$_{n}$S$_{n}$ ($n=1-8$) clusters are $n=3$ and 6. As cluster
size increases, the properties of Cd$_{n}$S$_{n}$ clusters tend to
bulk-like ones in binding energy per CdS unit and Mulliken atomic
charge, obtained by comparing with the calculated results of the
wurtzite and zinc blende CdS for the same simulating parameters.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

This paper reports that the ratios of double to single electron loss
cross-section (R) of O^{2+} in collision with Ar and He at the
velocity of 1--4\nu_{0} (\nu_{0} is the Bohr velocity) have been
obtained by the coincidence technique. The trend of R-V in the
experiment indicates that the effective charge varies with injected
velocity. The effective charge can be obtained by the n-body
classical trajectory Monte Carlo method, which is interpreted by the
molecular Coulomb over barrier model.

This paper investigates the propagation of linear dust acoustic
waves in inhomogeneous dusty plasmas due to spatial gradients of
dust charge, plasma densities. A linear dispersion relation is
obtained with the non-adiabatic dust charge fluctuation and the
non-thermally distributed ions. The numerical results show that the
inhomogeneity, non-thermal ions and non-adiabatic dust charge
fluctuation have strong influence on the frequency and the damping
rate of waves.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

Under a simple shear flow and in a static external magnetic field,
the production of defects in the director-aligning regime of nematic
liquid crystals has been investigated in terms of the
Leslie--Ericksen theory. The equation of motion of the nematic
director, which conforms to the driven over-damped sine-Gordon
equation, has a soliton solution of the amplitude $\pi$. We show that
the stationary state with the director uniformly oriented at a Leslie
angle is only a metastable state and the potential, which governs the
motion of the director, has a number of stable stationary states. For
a strong magnetic field, the higher energy barrier between the stable
and unstable states leads the director to be locked along the
magnetic field direction. However, at the appropriate shear rate and
magnetic field the defects, which appear as a stable solitary
solution, can be nucleated from a uniformly aligned nematic liquid
crystal. We have calculated the stationary travelling velocity of the
solitary waves and the distance between a pair of defects.

Using the complex variable function method and the technique of
conformal mapping, the anti-plane shear problem of an elliptic hole
with asymmetric collinear cracks in a one-dimensional hexagonal
quasi-crystal is solved, and the exact analytic solutions of the
stress intensity factors (SIFs) for mode III problem are obtained.
Under the limiting conditions, the present results reduce to the
Griffith crack and many new results obtained as well, such as the
circular hole with asymmetric collinear cracks, the elliptic hole
with a straight crack, the mode T crack, the cross crack and so on.
As far as the phonon field is concerned, these results, which play
an important role in many practical and theoretical applications,
are shown to be in good agreement with the classical results.

This paper have performed molecular static calculations with the
quantum corrected Sutten--Chen type many body potential to study
size effects on the elastic modulus of Au nanowires with [100],
[110] and [111] crystallographic directions, and to explore the
preferential growth orientation of Au nanowires. The main focus of
this work is the size effects on their surface characteristics.
Using the common neighbour analysis, this paper deduces that surface
region approximately consists of two layer atoms. Further, it
extracts the elastic modulus of surface, and calculate surface
energy of nanowire. The results show that for all three directions
the Young's modulus of nanowire increases as the diameter increases.
Similar trend has been observed for the Young's modulus of surface.
However, the atomic average potential energy of nanowire shows an
opposite change. Both the potential and surface energy of [110]
nanowire are the lowest among all three orientational nanowires,
which helps to explain why Au nanowires possess a [110] preferred
orientation during the experimental growth proceeds.

The power dissipation characteristics of pulsed power switch
reversely switched dynistors (RSDs) are investigated in this paper.
According to the expressions of voltage on RSD, derived from the
plasma bipolar drift model and the RLC circuit equations of RSD main
loop, the simulation waveforms of current and voltage on RSD are
acquired through iterative calculation by using the fourth order
Runge--Kutta method, then the curve of transient power on RSD versus
time is obtained. The result shows that the total dissipation on RSD
is trivial compared with the pulse discharge energy and the
commutation dissipation can be nearly ignored compared with the
quasi-static dissipation. These characteristics can make the
repetitive frequency of RSD increase largely. The experimental
results prove the validity of simulation calculations. The influence
factors on power dissipation are discussed. The power dissipation
increases with the increase of the peak current and the n-base width
and with the decrease of n-base doping concentration. In order to
keep a low power dissipation, it is suggested that the n-base width
should be smaller than 320$\mu $m when doping concentration is
1.0$\times $10$^{14}$cm$^{ - 3}$ while the doping concentration
should be higher than 5.8$\times $10$^{13}$cm$^{ - 3}$ when n-base
width is 270$\mu $m.

The modified analytic embedded-atom method and molecular dynamics
simulations are applied to the investigation of the surface
premelting and melting behaviours of the V(110) plane by calculating
the interlayer relaxation, the layer structure factor and atomic
snapshots in this paper. The results obtained indicate that the
premelting phenomenon occurs on the V(110) surface at about 1800K
and then a liquid-like layer, which approximately keeps the same
thickness up to 2020K, emerges on it. We discover that the
temperature 2020K the V(110) surface starts to melt and is
in a completely disordered state at the temperature of 2140K under
the melting point for the bulk vanadium.

This paper investigates the electronic structure and thermodynamic
properties of LiBC in the hexagonal structure by using the
generalized gradient approximation (GGA) and local density
approximation correction scheme in the frame of density functional
theory. The geometric structure of LiBC under zero pressure, and the
dependences of the normalized lattice parameters $a/a_{0}$ and
$c/c_{0}$, the ratio $c/a$, the normalized primitive volume
$V/V_{0}$ on pressure are given. The thermodynamic quantity
(including the heat capacity $C_{V}$, Debye temperature $\Th _{\rm
D}$, thermal expansion $\alpha $ and Gr\"{u}neisen parameter
\textit{$\gamma $}) dependences on temperature and pressure are
obtained through the GGA method and the quasi-harmonic Debye model.
The band structures and density of state of LiBC under different
pressures have also been analysed.

In this paper molecular dynamics simulations are performed to study
the accumulation behaviour of N$_{2}$ and H$_{2}$ at water/graphite
interface under ambient temperature and pressure. It finds that both
N$_{2}$ and H$_{2}$ molecules can accumulate at the interface and
form one of two states according to the ratio of gas molecules
number to square of graphite surface from our simulation results:
gas films (pancake-like) for a larger ratio and nanobubbles for a
smaller ratio. In addition, we discuss the stabilities of
nanobubbles at different environment temperatures. Surprisingly, it
is found that the density of both kinds of gas states can be greatly
increased, even comparable with that of the liquid N$_{2}$ and
liquid H$_{2}$. The present results are expected to be helpful for
the understanding of the stable existence of gas film (pancake-like)
and nanobubbles.

In this paper first-principles calculations of Ni(111)/$\alpha
$-Al$_{2}$O$_{3}$(0001) interfaces have been performed, and are
compared with the preceding results of the Cu (111)/$\alpha
$-Al$_{2}$O$_{3}$(0001) interface [2004 {\em Phil. Mag. Lett.}
\textbf{84} 425]. The Al-terminated and O-terminated interfaces have
quite different adhesion mechanisms, which are similar to the
Cu(111)/$\alpha $-Al$_{2}$O$_{3}$(0001) interface. For the
O-terminated interface, the adhesion is caused by the strong
O-2p/Ni-3d orbital hybridization and ionic interactions. On the
other hand, the adhesion nature of the Al-terminated interface is
the image-like electrostatic and Ni--Al hybridization interactions,
the latter is substantial and cannot be neglected. Charge transfer
occurs from Al$_{2}$O$_{3}$ to Ni, which is opposite to that in the
O-terminated interface. The charge transfer direction for the
Al-terminated and O-terminated
Ni(111)/$\alpha$-Al$_{2}$O$_{3}$(0001) interfaces is similar to that
in the corresponding Cu(111)/$\alpha$-Al$_{2}$O$_{3}$(0001)
interface, but there exist the larger charge transfer quantity and
consequent stronger adhesion nature, respectively.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

We have studied the spin-dependent electron transmission through a
quantum well driven by both dipole-type and homogeneous oscillating
fields. The numerical evaluations show that Dresselhaus spin--orbit
coupling induces the splitting of asymmetric Fano-type resonance
peaks in the conductivity, in which the dipole modulation and the
homogeneous modulation are\ equivalent. Therefore, we predict that
the dipole-type oscillation, which is more practical in the
experimental setup, can be used to realize the tunable spin filters
by adjusting the field oscillation-frequency and the amplitude as
well.

We have investigated theoretically the field-driven
electron-transport through a double-quantum-well
semiconductor-heterostructure with spin--orbit coupling. The
numerical results demonstrate that the transmission spectra are
divided into two sets due to the bound-state level-splitting and
each set contains two asymmetric resonance peaks which may be
selectively suppressed by changing the difference in phase between
two driving fields. When the phase difference changes from $0$ to
$\pi$, the dip of asymmetric resonance shifts from one side of
resonance peak to the other side and the asymmetric Fano resonance
degenerates into the symmetric Breit--Wigner resonance at a critical
value of phase difference. Within a given range of incident electron
energy, the spin polarization of transmission current is completely
governed by the phase difference which may be used to realize the
tunable spin filtering.

We have evaluated the effects of recombination processes in a charge
storage layer, either between trapped electrons and trapped holes or
between trapped carriers and free carriers, on charge trapping
memory cell's performances by numerical simulation. Recombination is
an indispensable mechanism in charge trapping memory. It helps
charge convert process between negative and positive charges in the
charge storage layer during charge trapping memory
programming/erasing operation. It can affect the speed of
programming and erasing operations.

This paper reports that indium tin oxide (ITO) crystalline powders
are prepared by coprecipitation method. Fabrication conditions
mainly as sintering temperature and Sn doping content are correlated
with the phase, microstructure, infrared emissivity $\varepsilon $
and powder resistivity of indium tin oxides by means of x-ray
diffraction, Fourier transform infrared, and transmission electron
microscope. The optimum sintering temperature of 1350${^\circ}$C and
Sn doping content 6$\sim $8wt{\%} are determined. The application of
ITO in the military camouflage field is proposed.

To reveal the internal physics of the low-temperature mobility of
two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures, we
present a theoretical study of the strong dependence of 2DEG mobility
on Al content and thickness of AlGaN barrier layer. The theoretical
results are compared with one of the highest measured of 2DEG
mobility reported for AlGaN/GaN heterostructures. The 2DEG mobility
is modelled as a combined effect of the scattering mechanisms
including acoustic deformation-potential, piezoelectric, ionized
background donor, surface donor, dislocation, alloy disorder and
interface roughness scattering. The analyses of the individual
scattering processes show that the dominant scattering mechanisms are
the alloy disorder scattering and the interface roughness scattering
at low temperatures. The variation of 2DEG mobility with the barrier
layer parameters results mainly from the change of 2DEG density and
distribution. It is suggested that in AlGaN/GaN samples with a high
Al content or a thick AlGaN layer, the interface roughness scattering
may restrict the 2DEG mobility significantly, for the AlGaN/GaN
interface roughness increases due to the stress accumulation in AlGaN
layer.

In this paper, we have discussed the effect of electrical stress on
GaN light emitting diode (LED). With the lapse of time, the LED with
an applied large current stress can reduce its current more than
without such a stress under a large forward-voltage drop. Its
scanning electron microscopy (SEM) image shows that there exist
several pits on the surface of the p-metal. With an electrical
stress applied, the number of pits greatly increases. We also find
that the degradation of GaN LED is related to the oxidized Ni/Au
ohmic contact to p-GaN. The electrical activation of H-passivated Mg
acceptors is described in detail. Annealing is performed in ambient
air for 10 min and the differential resistances at a forward-voltage
drop of 5\,V are taken to evaluate the activation of the Mg
acceptors. These results suggest some mechanisms of degradation
responsible for these phenomena, which are described in the paper.

We present mathematical analyses of the evolution of solutions of
the self-consistent equation derived from variational calculations
based on the displaced-oscillator-state and the
displaced-squeezed-state in spin-boson model at a zero temperature
and a finite temperature. It is shown that, for a given spectral
function defined as $J(\omega)=\pi\sum_k c_k^2=\ddfrac{\pi}{2}\alpha
\omega^{ s}\omega_{\rm c}^{ 1-s}$, there exists a universal $s_{\rm
c}$ for both kinds of variational schemes, the localized transition
happens only for $s\le s_{\rm c}$, moreover, the localized
transition is discontinuous for $s

This paper reports that the Schottky junctions between low work
function metals (e.g. Al and In) and doped semiconducting polymer
pellets (e.g. polyaniline (PANI) microsphere pellet and polypyrrole
(PPy) nanotube pellet) have been prepared and studied. Since Ag is a
high work function metal which can make an ohmic contact with
polymer, silver paste was used to fabricate the electrodes. The
Al/PANI/Ag heterojunction shows an obvious rectifying effect as
shown in $I-V$ characteristic curves (rectifying ratio $\gamma = 5$
at $\pm $6\,V bias at room temperature). As compared to the
Al/PANI/Ag, the heterojunction between In and PANI (In/PANI/Ag)
exhibits a lower rectifying ratio $\gamma = 1.6$ at $\pm $2\,V bias
at room temperature. In addition, rectifying effect was also
observed in the heterojunctions Al/PPy/Ag ($\gamma = 3.2$ at $\pm
$1.6\,V bias) and In/PPy/Ag ($\gamma = 1.2$ at $\pm $3.0\,V bias).
The results were discussed in terms of thermoionic emission theory.

Strontium and oxygen co-doped La$_{1.937}$Sr$_{0.063}$CuO$_{4 +
\delta }$ superconductor with $T_{\rm c}\approx 40$\,K, which is
obtained by oxidizing strontium-doped starting ceramic sample
La$_{1.937}$Sr$_{0.063}$CuO$_{4}$ in NaClO solution, is annealed
under different conditions to allow interstitial oxygen to
redistribute. The evolution of the intrinsic superconducting
property with the oxygen redistribution is studied in detail by
magnetic measurements in various fields. It is found that there
occurs the electronic phase separation from the single
superconducting phase with $T_{\rm c} \approx40$\,K into two
coexisting superconducting states with values of $T_{\rm c}$: 15 and
40\,K or of 15 and 35\,K in this system, depending on annealing
condition. Our results indicate that the 15, 35 and 40\,K
superconducting phases associated with the excess oxygen
redistribution are all thermodynamically meta-stable intrinsic
states in this Sr/O co-doped cuprate.

Owing to the inhomogeneous state resulting from the doping of a
small number of Eu ions into La$_{4 / 3}$Sr$_{5 /
3}$Mn$_{2}$O$_{7}$, from the resulting single crystal
(La$_{0.8}$Eu$_{0.2})_{4 / 3}$Sr$_{5 / 3}$Mn$_{2}$O$_{7}$ we have
observed the magnetization jump, the resistivity jump, as well as
the relaxation phenomena. For (La$_{0.8}$Eu$_{0.2})_{4 / 3}$Sr$_{5 /
3}$Mn$_{2}$O$_{7}$, it has a very delicate ground state due to the
interplays among spin, charge, orbital, lattice degrees of freedom.
Consequently, the magnetization state is sensitive to temperature,
magnetic field, as well as time. Meanwhile, the evolution of the
magnetization with time shows a spontaneous jump when both the
temperature and the magnetic field are constant. Similar step-like
behaviours are also observed in resistivity. All these results
suggest that Eu doping can greatly modulate the physical properties
of La$_{4 / 3}$Sr$_{5 / 3}$Mn$_{2}$O$_{7}$ and cause such
interesting behaviours.

We have performed magnetization measurements and electron spin
resonance (ESR) on polycrystalline manganites of Nd$_{0.5}$Sr$_{0.5 -
x}$Ba$_{x}$MnO$_{3}$ ($x = 0.1$). Phase separation and phase
transitions are observed from the susceptibility and the ESR spectra
data. Between 260\,K ($\sim T_{\rm C})$ and 185\,K ($\sim T_{\rm
N})$, the system coexists of the paramagnetic phase and the
ferromagnetic (FM) phase. Between 185\,K and 140\,K, the system
coexists of the FM phase and the antiferromagnetic (AFM) phase. These
results indicate that the system has a very complex magnetic state
due to the origin of the instability stemming from manganite
Nd$_{0.5}$Sr$_{0.4}$Ba$_{0.1}$MnO$_{3}$ by partially substituting the
larger Ba$^{2 + }$ ions for the smaller Sr$^{2 + }$ ions.

A semicrystalline composite, 3, 4, 9, 10 perylenetetracarboxylic dianhydride
(PTCDA) doped N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (NPB), has been
fabricated and characterized. An organic light-emitting diode using such a
composite in hole injection exhibits the improved performance as compared
with the reference device using neat NPB in hole injection. For example, at a
luminance of 2000 cd/m$^{2}$, the former device gives a current efficiency of
2.0cd/A, higher than 1.6cd/A obtained from the latter device.
Furthermore, the semicrystalline composite has been shown thermally to be more
stable than the neat NPB thin film, which is useful for making organic light
emitting diodes with a prolonged lifetime.

Precipitation sequence is a typical nonlinear and chaotic
observational series, and studies on precipitation forecasts are
restricted to the use of traditional linear statistical methods,
especially when analysing the regional characteristics of
precipitation. In the context of 20 stations' daily precipitation
series (from 1956 to 2000) in South China (SC) and North China (NC),
we divide each precipitation series into many self-stationary
segments by using the heuristic segmentation algorithm (briefly BG
algorithm). For each station's precipitation series, we calculate
the exponent of power-law tail (EPT) of the cumulative probability
distribution of segments with a length larger than $l$ for
precipitation and temperature series. Our results show that the
power-law decay of the cumulative probability distribution of
stationary segments might be a common attribution for precipitation
and other nonstationary time series; the EPT somewhat indicates the
precipitation duration and its spatial distribution that might be
different from area to area. The EPT in NC is larger than in SC;
Meanwhile, EPT might be another effective way to study the abrupt
changes in nonlinear and nonstationary time series.