International Journal of Modern Physics B

The transient behavior of free convection along the vertical wire of a hot-wire apparatus has been experimentally investigated at room temperature and ambient pressure, using water and propylene glycol. The development of free convection has been studied using an ad hoc apparatus, in order to obtain the best agreement between the vertical direction and the wire. The measurements were corrected for radiation influences, and the effects induced by free convection were detected at the wire-fluid interface.

The convection outcomes have been correlated to fluid properties and test conditions. A suitable time scale has been introduced, which is defined by the modified Fourier and a proper definition of the local Grashof number. The obtained correlation has been applied to data found in the literature. The possibility of describing the free convection development at the wire-fluid interface could enable the fluid properties related to momentum diffusion to be investigated by the hot-wire technique.

This article deals with the connection between multipole matrix elements 〈nl|r^β|n'l'〉_ν and 〈nl|r^β|El'〉_ν for H-like atoms, where ν is the so-called "auxiliary" parameter of Heun's differential equation and is the "effective" nuclear charge, and new properties of Appell's function F₂(x,y) to the vicinity of the singular point (1, 1) and in addition, here, first V. A. Fock's idea for the continuous spectrum is taken into consideration. Such an approach allows us to get the explicit expressions for squares of the dipole moments and the certain physical characteristics in atomic physics and also their exact numerical values, e.g., the average oscillator strengths and the line intensities J(nl, El'), etc., as n ≤ 4, l'= l ± 1 and 0 ≤ E ≤ 1 (see Tables 1–3). Besides, diagrams of certain radial functions for the discrete-continuous transitions are given here.

This paper proposed a new dynamical friction model structure which allows accurate modeling both in sliding and presliding regimes. Transition between these two regimes is accomplished without a switching function. In the presliding regime, the model has the characters of a Bouc–Wen model, so it can adapt to various hysteretic behaviors. While in the gross-sliding regime, the model is equivalent to a general velocity-dependent friction model. Therefore, the dynamical characters of friction force in this regime, such as negative friction-velocity slope, can be described also. Furthermore, the transition between these two regimes is not abrupt, but smooth, and needs no extra function. The application of this model is demonstrated by describing experimentally obtained friction force for a guide–rail system. Numerical simulation results for a vibration system with friction show the practicability of the model to predict dynamic characteristics such as hysteretic behavior in presliding, velocity-dependent behavior in sliding, and stick-slip behavior.

A two-slit interference of a massive particle in the presence of environment-induced decoherence is theoretically analyzed. The Markovian Master equation, derived from coupling the particle to a harmonic-oscillator heat bath, is used to obtain exact solutions which show the existence of an interference pattern. Interestingly, decoherence does not affect the pattern, but only leads to a reduction in the fringe visibility.

MgB₂ thin films were deposited at low temperature substrates, in situ, on c-plane sapphire substrates, with the aluminium nitride (AlN) buffer layers, using the multiple-target sputtering system. The magnetoresistivities were measured using dc-five probe method in applied magnetic field up to 9 Tesla. The upper critical field anisotropy, H_C2(T) and irreversibility field H_irr(T) versus temperature were determined. The Hall coefficients R_H are slightly temperature dependent and positive in the normal state. The critical temperature of 30–32 K and critical current density of 10⁶-10⁷A/cm² at 4.2 K were obtained. Using extracted data, the coherence length ξ_o, anisotropic coefficient γ and penetration depth λ_L were calculated.

We investigate noise-induced synchronization in Lorenz systems. We find that common noise can induce synchronization even if its impact on the system is confined to a small region in the Lorenz phase space. The mechanism is revealed to be related to changes in the distribution of the attractor in the phase space.

We investigate the transitions between two minibands in a semiconductor superlattice under the influence of high static electric fields. Our numerical calculation, which is based on the two energy levels system, shows that this interminiband transition will lead to anticrossings that can be determined by the coupled Hamiltonian. In the time domain, spatial oscillations come forth between the main locations of the particle in the two transition states. At the anticrossings, the amplitudes are the maximum which agree with the experimental results.

This paper studies the adaptive synchronization and parameter identification of an uncertain hyperchaotic Chen system. Based on the Lyapunov stability theory, an adaptive control law is derived to make the states of two identical hyperchaotic Chen systems asymptotically synchronized. With this approach, the synchronization and parameter identification of the hyperchaotic Chen system with five uncertain parameters can be achieved simultaneously. Theoretical proof and numerical simulations demonstrate the effectiveness and feasibility of the proposed scheme.

With the help of the time-dependent gauge transformation, by which a set of time-invariant eigenstates of the Hamiltonian can be obtained, the geometric phase of the time-dependent system is obtained analytically. In the limit of the adiabatic condition, this phase exactly reduces to the adiabatic geometric phase. To illustrate the present theory, two solvable time-dependent systems are considered.