Effect of high-energy Ne ions irradiation on mechanical properties difference between Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5)metallic glass and crystalline W

In this paper,high-energy Ne ions were used to irradiate Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) metallic glass(MG)and crystalline W to investigate their difference in mechanical response after irradiation.The results showed that with the irradiation dose increased,the tensile micro-strain increased,nano-hardness increased from 7.11 GPa to 7.90 GPa and 8.62 GPa,Young’s modulus increased,and H3/E2 increased which indicating that the plastic deformability decreased in crystalline W.Under the same irradiation conditions,the Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG still maintained the amorphous structure and became more disordered despite the longer range and stronger displacement damage of Ne ions in Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG than in crystalline W.Unlike the irradiation hardening and embrittlement behavior of crystalline W,Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG showed the gradual decrease in hardness from 6.02 GPa to 5.89 GPa and 5.50 GPa,the decrease in modulus and the increase in plastic deformability with the increasing dose.Possibly,the irradiation softening and toughening phenomenon of Zr_(63.5)Cu_(23)Al_(9)Fe_(4.5) MG could provide new ideas for the design of nuclear materials.

The structure of an electronegative magnetized plasma sheath with non-extensive electron distribution

In this paper, an electronegative magnetized plasma sheath model with non-extensive electron distribution is established, and the Bohm criterion affected by the non-extensive parameter q is theoretically derived. The ion Mach number varies with q. The numerical simulation results show that compared with electronegative magnetized plasma sheath with Maxwell distribution(q=1), the sheath structures with super-extensive distribution(q<1) and sub-extensive distribution(q>1) are different. The physical quantities including the sheath potential distribution, ion density distribution, the electron density distribution, negative ion density distribution and the net space charge density distribution are discussed. It is shown that the non-extensive parameter q has a significant influence on the structure of the electronegative magnetized plasma sheath. Due to the Lorentz force, both the magnitude and the angle of the magnetic field affect the structure of the sheath, whether the electrons are Maxwell distributed or non-extensively distributed.

Energy Distribution of Ions Incident on Radio-Frequency Biased Electrodes in External Magnetic Field

A radio-frequency （rf） plasma sheath model in an oblique magnetic field is established and the energy distribution of ions （IED） incident on the rf sheath biased electrodes is numerically investigated. The simulation results reveal that the external magnetic field can have a decisive impact on the ion flux and energy distribution of the sheath. The ion energy can be transferred between the perpendicular and parallel components under the action of a magnetic field.

Little Hankel Operators on the Weighted Bergman Space of the Unit Ball

In this paper we mainly consider little Hankel operators with squareintegrable symbols on the weighted Bergman spaces of the unit ball.We obtain that Schatten class of little Hankel operators is equivalent to Schatten class of positive Toeplitz operators under the conditions that SMO（f） ∈ L p/2 （B n,dλ） and 2 ≤ p ∞,which is very important to research the relation between Toeplitz operators and little Hankel operators.

The irradiation variation of amorphous alloy FeSiB using for fusion devices induced by 2 MeV He ions

Because of its unique long range disordered structure and numerous free volume,amorphous alloy is considered to be able to accommodate the damage caused by ion bombardment and has good irradiation resistance.2 MeV He+ions were selected to irradiate amorphous alloy Fe80Si7B13,and it was found that the arrangement of atoms in the amorphous alloy became uneven.In the bubble layer located near the He ion range which was about 3.5μm from the surface,the local atoms had a tendency of ordered arrangement.Under the irradiation,no obvious damage could be observed on the surface of the amorphous alloy,while the surface roughness increased,which reduced the surface relative reflectivity of the amorphous alloy.After the irradiation,the Fe-based amorphous alloy maintained the soft magnetic performance.The variation of atomic arrangement in the amorphous alloy enhanced its saturation magnetic induction intensity.

Existence of Solutions to a Viscous Thin Film Equation

A fourth-order degenerate parabolic equation with a viscous term: ?is studied with the initial-boundary conditions ux=wx=0?on {-1,1}×(0,T), u(x,0)=u0(x)?in (-1,1). It can be taken as a thin film equation or a Cahn-Hilliard equation with a degenerate mobility. The entropy functional method is introduced to overcome the difficulties that arise from the degenerate mobility m(u)?and the viscosity term. The existence of nonnegative weak solution is obtained.

A NEW CORRENTROPY BASED TDE METHOD UNDER α-STABLE DISTRIBUTION NOISE ENVIRONMENT

This paper presents a robust time delay estimation algorithm for the α-Stable noise based on correntropy. Many time delay estimation algorithms derived for impulsive stable noise are based on the theory of Fractional Lower Order Statistics (FLOS). Unlike previously introduced FLOS-type algorithms, the new algorithm is proposed to estimate the time delay by maximizing the generalized correlation function of two observed signals needing neither prior information nor estimation of the numerical value of the stable noise's characteristic exponent. An interval for kernel selection is found for a wide range of characteristic exponent values of α-Stable distribution. Simulations show the proposed algorithm offers superior performance over the existing covariation time delay estimation, least mean p-norm time delay estimation and achieves slightly improved performance than fractional lower order covariance time delay estimation at lower signal to noise ratio when the noise is highly impulsive.

GLOBAL NONEXISTENCE FOR A VISCOELASTIC WAVE EQUATION WITH ACOUSTIC BOUNDARY CONDITIONS

This paper deals with a class of nonlinear viscoelastic wave equation with damping and source terms utt-Δu-Δut-Δutt+∫^t0g(t-s)Δu(s)ds+ut|ut|^m2-=u|u|^p-2 with acoustic boundary conditions.Under some appropriate assumption on relaxation function g and the initial data,we prove that the solution blows up in finite time if the positive initial energy satisfies a suitable condition.

Sheath Criterion for an Electronegative Plasma Sheath in an Oblique Magnetic Field

The sheath criterion for an electronegative plasma composed of hot electrons,hot negative ions and cold positive ions in an oblique magnetic field is investigated.We discuss the effects of negative ions and external magnetic field on the sheath criterion.We find that the ion Mach number is of relatively low value because of Coulomb attraction between positive and negative ions.Also the ion Mach number depends on the magnitude and the angle of the magnetic field as well as the initial velocity of ion flow.

Reagent Vibration Effect on the Stereodynamics for the C+CD→C2+D Reaction

We study the effect of the reagent vibration of the CD on the stereodynamics of the C+CD→C2+D reaction by using the quasi-classical trajectory method at a collision energy of 2.306 kcal/mol on the potential energy surface of the 12𝐴′state[Boggio-Pasqua et al.Mol.Phys.98(2000)1925].The vector correlation distributions𝑝(θr)and the dihedral-angle distribution𝑝(Φr)as well as𝑝(θr,Φr)are calculated.In addition,two polarizationdependent generalized differential cross sections of the product are presented and discussed within a center-ofmass framework.The results show that the effect of reagent vibration can cause obviously different effects on the stereodynamics of the title reaction.

Bohm Criterion in a Magnetized Plasma Sheath

Bohm criterion in a magnetized plasma sheath is investigated with a fluid model. The upper and lower limits for the sheath criterion in different states of applied magnetic field are studied. The results from numerical simulation reveal that the magnetic field affects significantly the ion Mach number. The variation of the ion Mach number with the incident angle of the ions is also presented.

Sheath Criterion for a Collisional Electronegative Plasma Sheath in an Applied Magnetic Field

The sheath criterion for a collisional electronegative plasma sheath in an applied magnetic field is investigated.It is assumed that the system consists of hot electrons,hot negative ions and cold positive ions.The effect of an applied magnetic field on the sheath criterion is discussed.The results reveal that the magnetic field has effects on both the upper and lower limits,which cause the range of the ion Mach number to increase.In addition,the numerical calculations of the electronegative plasma sheath are carried out to demonstrate the effects of sheath criterion on the characteristics of the sheath.

A NATURAL GRADIENT ALGORITHM FOR THE SOLUTION OF LYAPUNOV EQUATIONS BASED ON THE GEODESIC DISTANCE

A new framework based on the curved Riemannian manifold is proposed to calculate the numerical solution of the Lyapunov matrix equation by using a natural gradient descent algorithm and taking the geodesic distance as the objective function. Moreover, a gradient descent algorithm based on the classical Euclidean distance is provided to compare with this natural gradient descent algorithm. Furthermore, the behaviors of two proposed algorithms and the conventional modified conjugate gradient algorithm are compared and demonstrated by two simulation examples. By comparison, it is shown that the convergence speed of the natural gradient descent algorithm is faster than both of the gradient descent algorithm and the conventional modified conjugate gradient algorithm in solving the Lyapunov equation.

The α-Geometric Structures on Manifold of Positive Definite Hermite Matrices

Geometric structures of a manifold of positive definite Hermite matrices are considered from the viewpoint of information geometry.A Riemannian metric is defined and dual α-connections are introduced.Then the fact that the manifold is ±l-flat is shown.Moreover,the divergence of two points on the manifold is given through dual potential functions.Furthermore,the optimal approximation of a point onto the submanifold is gotten.Finally,some simulations are given to illustrate our results.

Toeplitz Operators with BMO Symbols on the Weighted Bergman Space of the Unit Ball

In this paper we prove that the boundedness and compactness of Toeplitz operator with a BMOα1 symbol on the weighted Bergman space Aα2（Bn） of the unit ball is completely determined by the behavior of its Berezin transform, where ≥ -1 and n 〉 1.

Stochastic stability of fuzzy Markovian jump neural networks by multiple integral approach

Purpose–The purpose of this paper is to develop a methodology for the stochastically asymptotic stability of fuzzy Markovian jumping neural networks with time-varying delay and continuously distributed delay in mean square.Design/methodology/approach–The authors perform Briat Lemma,multiple integral approach and linear convex combination technique to investigate a class of fuzzy Markovian jumping neural networks with time-varying delay and continuously distributed delay.New sufficient criterion is established by linear matrix inequalities conditions.Findings–It turns out that the obtained methods are easy to be verified and result in less conservative conditions than the existing literature.Two examples show the effectiveness of the proposed results.Originality/value–The novelty of the proposed approach lies in establishing a new Wirtinger-based integral inequality and the use of the Lyapunov functional method,Briat Lemma,multiple integral approach and linear convex combination technique for stochastically asymptotic stability of fuzzy Markovian jumping neural networks with time-varying delay and continuously distributed delay in mean square.

Stochastic synchronization of neutral-type chaotic impulse neural networks with leakage delay and Markovian jumping parameters

Purpose-The purpose of this paper is to develop a methodology for the stochastically asymptotic synchronization problem for a class of neutral-type chaotic neural networks with both leakage delay and Markovian jumping parameters under impulsive perturbations.Design/methodology/approach-The authors perform drive-response concept and time-delay feedback control techniques to investigate a class of neutral-type chaotic neural networks with both leakage delay and Markovian jumping parameters under impulsive perturbations.New sufficient criterion is established without strict conditions imposed on the activation functions.Findings-It turns out that the approach results in new sufficient criterion easy to be verified but without the usual assumption of the differentiability and monotonicity of the activation functions.Two examples show the effectiveness of the obtained results.Originality/value-The novelty of the proposed approach lies in removing the usual assumption of the differentiability and monotonicity of the activation functions,and the use of the Lyapunov functionalmethod,Jensen integral inequality,a novel Gu’s lemma,reciprocal convex and linear convex combination technique for the stochastically asymptotic synchronization problem for a class of neutral-type chaotic neural networks with both leakage delay and Markovian jumping parameters under impulsive perturbations.

Photoassociation reaction of OH molecules through reverse ladder transition

Photoassociation via reverse ladder transition controlled by two and four laser pulses is investigated using the time-dependent quantum wave packet method. The calculated results show that the amplitudes of the pulses have an enormous effect on the target population and total yield of association. For the target state with a high energy level, the population of background states can reduce the state-selectivity. Although, the total yield of association is decreased, the four pulses can induce the population transferring to low vibrational levels, and the state-selectivity of the target state is high.

Theoretical calculation on distance amplitude curve of ultrasonic phased array

Ultrasonic phased array technology has been gradually applied to industrial nondestructive testing in recent years.The sound field of the focusing and steering beam radiating from the phased array is a nonuniform distribution in the spatial position so that the echo signals of same size defects will be changed according to defect positions.To analyze these defects quantitatively,a model-based method for the distance amplitude correction is proposed for the phased array system.Based on a non-paraxial multi-Gaussian beam model and flaw scattering models,an ultrasonic measurement model for the phased array system is proposed to calculate the echo signals from side-drilled holes at different positions.Furthermore,these model-based distance amplitude curves are compared with the traditional experimental results for different focusing and steering beams.The two methods have a good agreement.

CHAOS ANALYSIS AND CONTROL FOR A CLASS OF SIR EPIDEMIC MODEL WITH SEASONAL FLUCTUATION

In this paper, the problems of chaos and chaos control for a class of susceptible-infected- removed （SIR） epidemic model with seasonal fluctuation are investigated. The season- ality in outbreak is natural among infectious diseases, as the common influenza, A type H1N1 influenza and so on. It is shown that there exist chaotic phenomena in the epidemic model. Furthermore, the tracking control method is used to control chaotic motions in the epidemic model. A feedback controller is designed to achieve tracking of an ideal out- put. Thus, the density of infected individuals can converge to zero, in other words, thedisease can be disappeared. Finally, numerical simulations illustrate that the controller is effective.