Effects of Confined Laser Ablation on Laser Plasma Propulsion

We investigate the effects of confined laser ablation on laser plasma propulsion. Compared with planar ablation, the cavity ablation provides an effective way to obtain a large target momentum and a high coupling coefficient. When laser pulses are focused into a cavity with 1 mm diameter and 2ram depth, a high coupling coefficient is obtained. By using a glass layer to cover the cavity, the coupling coefficient is enhanced by 10 times. Meanwhile, it is found that with the increase of the target surface size, the target momentum presents a linear increase.     

The characteristics of confined ablation in laser propulsion

Compared with direct ablation, confined ablation provides an effective way to obtain a large target momentum and a high coupling coefficient. By using a transparent glass layer to cover the target surface, the coupling coefficient is enhanced by an order of magnitude. With the increase of the gap width between the target surface and the cover layer, the coupling coefficient exponentially decreases. It is found that the coupling coefficient is also related to the thickness of the cover layer.     

Analysis of the injection-locked magnetron with a mismatched circulator

Based on the scatter matrix of the four-port lossless mismatched circulator, the phase differential equation of the injection-locked magnetron is derived by comparing different effects of the mismatched and perfect circulator on the injection ratio. Besides, the locking range of the injection-locked magnetron with the mismatched circulator is deduced by functional operation. In addition, the phase differential equation and the locked bandwidth of the injection-locked system with a mismatched circulator are compared with those of the small injection-ratio case with a perfect circulator. The influence of the circulator reflection coefficient on the injection-locked magnetron is also analyzed by numerical calculation.Theoretical analysis shows that the decrement of the locked bandwidth is less than 1% and decrement of the stable phase difference is less than 1.2% when the reflection coefficient is less than 0.1.     

A Polydisperse Sphere Model Describing the Propagation of Light in Biological Tissue

A polydisperse sphere model with the complex refractive index is employed to describe the propagation of light in biological tissue. The scattering coefficient, absorption coefficient and scattering phase function are calculated. At the same time, the inverse problem on retrieving the particles size distribution, imaginary part of the refractive index and number density of scatterers is investigated. The result shows that the retrieval scheme together with the Chahine algorithm is effective in dealing with such an inverse problem. It is also clarified that a group of parameters including the scattering coefficient, absorption coefficient and phase function are associated with another group including the refractive index, particle size distribution and number density of scatterers, which is a problem described in two different ways and the anisotropy factor is not an independent variable, but is determined by the phase function.     

Exit selection strategy in pedestrian evacuation simulation with multi-exits

A mixed strategy of the exit selection in a pedestrian evacuation simulation with multi-exits is constructed by fusing the distance-based and time-based strategies through a cognitive coefficient, in order to reduce the evacuation imbalance caused by the asymmetry of exits or pedestrian layout, to find a critical density to distinguish whether the strategy of exit selection takes effect or not, and to analyze the exit selection results with different cognitive coefficients. The strategy of exit selection is embedded in the computation of the shortest estimated distance in a dynamic parameter model, in which the concept of a jam area layer and the procedure of step-by-step expending are introduced. Simulation results indicate the characteristics of evacuation time gradually varying against cognitive coefficient and the effectiveness of reducing evacuation imbalance caused by the asymmetry of pedestrian or exit layout. It is found that there is a critical density to distinguish whether a pedestrian jam occurs in the evacuation and whether an exit selection strategy is in effect. It is also shown that the strategy of exit selection has no effect on the evacuation process in the no-effect phase with a low density, and that evacuation time and exit selection are dependent on the cognitive coefficient and pedestrian initial density in the in-effect phase with a high density.     

Wavelength Dependence of Electro—Optic Coefficients in Chromophore—Incorporated Polymers

Wavelength dependence of electro-optic coefficients in chromophore-incorporated polymers is studied by using the attenuated-total-reflection technique.Experimental result shows that the electro-optic coefficient decreases with increasing light wavelength,which is in agreement well with the theoretical prediction.     

A cellular automata traffic flow modeling of desired speed variability

The satisfaction rate of desired velocity in the case of a mixture of fast and slow vehicles is studied by using a cellular automaton method. It is found that at low density the satisfaction rate depends on the maximal velocity. However, the behavior of the satisfaction rate as a function of the coefficient of variance is independent of the maximal velocity. This is in good agreement with empirical results obtained by Lipshtat [Phys. Rev. E 79 066110 (2009)]. Furthermore, our numerical result demonstrates that at low density the satisfaction rate takes higher values, whereas the coefficient of variance is close to zero. The coefficient of variance increases with increasing density, while the satisfaction rate decreases to zero. Moreover, we have also shown that, at low density the coefficient variance depends strongly on the probability of overtaking.     

Long—Range Effects on the Pyroelectric Coefficient of Ferroelectric Superlattice

Long-range effects on the pyroelectric coefficient of a ferroelectric superlattice consisting of two different ferroelectric materials are investigated based on the transverse Ising model.The effects of the interfacial coupling and the thickness of one period on the pyroelectric coefficient of the ferroelectric superlattics are studied by taking into account the long-range interaction.It is found that with the increase of the strength of the long-range interaction,the pyroelectric coefficient decreases when the temperature is lower than the phase transition temperature;the mumber of the pyroelectric peaks decreases gradually and the phase transition temperature increases,It is also found that with the decrease of the interfacial coupling and the thickness of one period.the phase transition temperature and the number of the pyroelectric peaks decrease.     

Irradiation effect on strain sensitivity coefficient of strain sensing fiber Bragg gratings

The effect of irradiation on the strain sensitivity coefficient of strain sensing fiber Bragg gratings(FBGs) has been investigated through experiments. FBGs were fabricated in single mode fibers with 3 mol% Ge-concentration in the core and with a H2-loading treatment. In experiments, the FBGs were subjected to γ-radiation exposures using a Co60 source at a dose-rate of 25 Gy/min up to a total dose of 10.5 kGy. The GeO defect in fiber absorbs photons to form a GeE’ defect; the interaction with H2 is a probable reason for the γ-radiation sensitivity of gratings written in hydrogen loaded fibres. The effect mechanism of radiation on the strain sensitivity coefficient is similar to that of radiation on the temperature sensitivity coefficient. Radiation affects the effective index neff, which results in the change of the thermo-optic coefficient and the strain-optic coefficient. Irradiation can change the strain sensitivity coefficient of FBGs by 1.48%–2.71%, as well as changing the Bragg wavelength shift(BWS) by 22 pm–25 pm under a total dose of 10.5 kGy. Our research demonstrates that the effect of irradiation on the strain sensitivity coefficient of FBG is small and that strain sensing FBGs can work well in the radiation environment.     

Investigation on electromagnetic scattering from rough soil surface of layered medium using the small perturbation method

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 blstatic 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.     

Dirac operator on the sphere with attached wires

An explicitly solvable model for tunnelling of relativistic spinless particles through a sphere is suggested. The model operator is constructed by an operator extensions theory method from the orthogonal sum of the Dirac operators on a semiaxis and on the sphere. The transmission coefficient is obtained. The dependence of the transmission coefficient on the particle energy has a resonant character. One observes pairs of the Breit–Wigner and the Fano resonances. It correlates with the corresponding results for a non-relativistic particle.     

Time-Delay Enhanced Coherence Resonance in a Discrete Neuron with Noises

Coherence resonance in a discrete excitable neuronal model with noises and time delays is investigated. The effects of the time delays on coherence resonance are revealed in two cases： Gaussian white and Gaussian color noises, respectively. The coefficient of variation of interspike intervals is calculated by numerical simulation. The results show that the coherence resonance is enhanced with the time delay increasing in the weak noises intensity cases, while there is no effect in the large noise intensity. Moreover, the coherence resonance can be held back by the self-correlation time, when the system is driven by a color noise.     

Measurement of the friction coefficient of a fluctuating contact line using an AFM-based dual-mode mechanical resonator

A dual-mode mechanical resonator using an atomic force microscope （AFM） as a force sensor is developed. The resonator consists of a long vertical glass fiber with one end glued onto a rectangular cantilever beam and the other end immersed through a liquid-air interface. By measuring the resonant spectrum of the modified AFM cantilever, one is able to accurately determine the longitudinal friction coefficient ξv along the fiber axis associated with the vertical oscillation of the hanging fiber and the traversal friction coefficient ξh perpendicular to the fiber axis associated with the horizontal swing of the fiber around its joint with the cantilever. The technique is tested by measurement of the friction coefficient of a fluctuating （and slipping） contact line between the glass fiber and the liquid interface. The experiment verifies the theory and demonstrates its applications. The dual-mode mechanical resonator provides a powerful tool for the study of the contact line dynamics and the rheological property of anisotropic fluids.     

Stationary Fluid Dynamic Behaviour of V-Shaped Diffuser/Nozzle Elements for Valveless Micropump

A novel type of V-shaped （isosceles triangle cross-section） diffuser/nozzle element is proposed for use for valveless micropump. Stationary fluid dynamic behaviour of V-shaped diffuser/nozzle elements in a valveless micropump is investigated by experiment and simulation. Both the results agree well with each other when the Reynolds number is higher than 100 and the pressure loss coefficient ratio of micropump nearly always keeps a constant. For a single V-shaped diffuser, the general trends of variation of pressure loss coefficient with opening angle and Reynolds number are opposite in small and large angles. Compared with conical and flat-wall diffusers, V-shaped diffuser shows the smallest pressure loss when the Reynolds number is 200.     

Remote State Preparation with Genuine Multipartite Entanglement

Enlightened by the work of Yeo and Chua [Phys. Rev. Lett. 96 （2006） 060502] for teleportation and dense coding with genuine multipartite entanglement, we present an explicit protocol for faithful remote state preparation in a real coefficient case by using the same four-particle entangled state which is not reducible to pair of Bell states. It is shown that any complex coefficient case can be changed to a real coefficient case. With this protocol, the state can play an analogous role to Einstein-Podolsky-Rosen pairs in the theory of multipartite entanglement.     

Statistical Entropy of an Acoustic Black Hole in Bose–Einstein Condensates

The entanglement entropy of an acoustic black hole in a Bose-Einstein condensates （BEC） is derived, which is associated with the phonons generated via the Hawking mechanism in a sonic hole. Considering the dispersion relation of a BEC, we recalculate the entanglement entropy of the acoustic black hole by means of statistical method in two limits. We find that the entropy is still proportional to the area of event horizon, but with a coefficient dependent on the infrared cutoff.     

Efficient and Robust Design for Absorbing Boundary Conditions in Atomistic Computations

We propose an efficient and robust way to design absorbing boundary conditions in atomistic computations. An optimal discrete boundary condition is obtained by minimizing a functional of a reflection coefficient integral over a range of wave numbers. The minimization is performed with respect to a set of wave numbers, at which transparent absorption is reached. Compared with the optimization with respect to the boundary condition coefficients suggested by E and Huang [Phys. Rev. Lett. 87 （2001） 133501], we reduce considerably the number of independent variables and the computing cost. We further demonstrate with numerical examples that both the optimization and the wave absorption are more robust in the proposed design.     

Transport properties of a binary mixture of CO₂-N₂ from the pair potential energy functions based on a semi-empirical inversion method

The potential energy surface of a CO 2 –N 2 mixture is determined by using an inversion method, together with a new collision integral correlation [J. Phys. Chem. Ref. Data 19 1179 (1990)]. With the new invert potential, the transport properties of CO2–N2 mixture are presented in a temperature range from 273.15 K to 3273.15 K at low density by employing the Chapman–Enskog scheme and the Wang Chang–Uhlenbeck–de Boer theory, consisting of a viscosity coefficient, a thermal conductivity coefficient, a binary diffusion coefficient, and a thermal diffusion factor. The accuracy of the predicted results is estimated to be 2% for viscosity, 5% for thermal conductivity, and 10% for binary diffusion coefficient.     

THE ACOUSTOELECTRIC EFFECT IN α-LiIO_3 CRYSTAL

In α-LiIO_3 crystal,the attenuation coefficient of longitudinal wave is increased by the action of anelectrostatic field,if the direction of wave propagating and the field are along the same c-axis of the crystal.The change of the attenuation coefficient with time possesses a relaxation character.We believe that thisphenomenon may be caused by the interaction between the longitudinal wave and the unilaterally moving