δ/γ transformation in non-equilibrium solidified peritectic Fe-Ni alloy

Through phase transformation kinetic analysis and experimental observation, the δ/γ transformation occurring in the non-equilibrium peritectic Fe-4.33at.%Ni alloys was systematically investigated. According to JMA solid-state transformation kinetic theory, the Time-Temperature-Transformation (TTT) curves of the δ/γ transformation in peritectic Fe-Ni alloy were calculated. On this basis, the physical correlation between the δ/γ transformation and the initial undercooling of melt (△T) was elucidated. The results indicate that the change of △T can alter not only the overall δ/γ transformation pathways but also the transformation fraction with respect to each transformation mechanism.     

Study on spatial resolution of micromegas as a neutron detector under condition of high neutron flux and γ ray background

In this paper Micromegas has been designed to detect neutrons. The simulation of the spatial reso-lution of Micromegas as neutron detector is carried out by GEANT4 toolkit. The neutron track reconstruction method based on the time coincidence technology is employed in the present work. The influence of the flux of incident 14 MeV neutron and high gamma background on the spatial resolution is carefully studied. Our results show that the spatial resolution of the detector is sensitive to the neutron flux, but insensitive to the intensity of γ background if the neutron track reconstruction method proposed by our group is used. The γ insensitivity makes it possible for us to use the Micromegas detector under condition which has high γ-rays background.     

Digital discrimination of neutron and γ ray using an organic scintillation detector based on wavelet transform modulus maximum

A novel algorithm for the discrimination of neutron and γ -ray events with wavelet transform modulus maximum (WTMM) in an organic scintillation has been investigated. Voltage pulses arising from a BC501A organic liquid scintillation detector in a mixed radiation field have been recorded with a fast digital sampling oscilloscope. The WTMM method using frequency-domain features exhibits a strong insensitivity to noise and can be used to discriminate neutron and γ -ray events based on their different asymptotic decay trend between the positive modulus maximum curve and the negative modulus maximum curve in the scale-space plane. This technique has been verified by the corresponding mixed-field data assessed by the time-of-flight (TOF) method and the charge comparison (CC) method. It is shown that the characterization of neutron and γ ray achieved by the discrimination method based on WTMM is consistent with that afforded by the TOF method and better than the CC method. Moreover, the WTMM method itself has presented its ability to eliminate the noise without any pretreatment to the pulses.     

Conditioning the γ spectrometer for activity measurement at very high background

The application of a high purity Germanium(HPGe) γ spectrometer in determining the fuel element burnup in a future reactor is studied.The HPGe detector is exposed by a 60Co source with varying irradiation rate from 10×103s-1 to 150×103s-1 to simulate the input counting rate in real reactor environment.A137 Cs and a152 Eu source are positioned at given distances to generate a certain event rate in the detector with the former being proposed as a labeling nuclide to measure the burnup of a fuel element.It is shown that both the energy resolution slightly increasing with the irradiation rate and the passthrough rate at high irradiation level match the requirement of the real application.The influence of the background is studied in the different parameter sets used in the specially developed procedure of background subtraction.It is demonstrated that with the typical input irradiation rate and 137Cs intensity relevant to a deep burnup situation,the precision of the 137Cs counting rate in the current experiment is consistently below 2.8%,indicating a promising feasibility of utilizing an HPGe detector in the burnup measurement in future bed-like reactors.     

Energy calibration of a BC501A liquid scintillator using a γ-γ coincidence technique

An accurate energy calibration of a BC501A liquid scintillator by means of Compton scattering of γ-rays is described.The energy resolution and the position of the Compton edge have been precisely determined using a γ-γ coincidence technique and fitting the coincidence spectrum with a Gaussian function superimposed on a quadratic polynomial for the background.The position of the Compton edge relative to the position of the maximum and the half height of the distribution in dependence on the relevant energy resolution is discussed in detail.The results indicate that the maximum energy of the recoil Compton electron does not occur at the half height distribution but at 0.90±0.05 of the maximum height in the energy range considered.The energy resolution varies from 15.6% to 8.02% for electrons in the energy region from 0.5 MeV to 3 MeV.     

High spin band structure in 139Nd

High-spin states in 139Nd nucleus have been reinvestigated with the reaction 128Te (16O, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2 h. At the low spin states,the yrast collective structure built on the vh(-1)(11/2) multiplet shows a transitional shape with γ≈32° according to calculations of the triaxial rotor-plus-particle model. Three collective oblate bands with γ～-60° at the high spin states were identified for the first time. A band crossing is observed around hw ～0.4 MeV in one oblate band based on the 25/2- level.     

From fractional Fourier transformation to quantum mechanical fractional squeezing transformation

By converting the triangular functions in the integration kernel of the fractional Fourier transformation to the hyperbolic function,i.e.,tan α→ tanh α,sin α→ sinh α,we find the quantum mechanical fractional squeezing transformation(FrST) which satisfies additivity.By virtue of the integration technique within the ordered product of operators(IWOP) we derive the unitary operator responsible for the FrST,which is composite and is made of e~(iπa~+a/2) and exp[iα/2(a~2 +a~(+2)).The FrST may be implemented in combinations of quadratic nonlinear crystals with different phase mismatches.     

狄拉克δ函数

从狄拉克δ函数8(x)的定义出发,说明其在x=0处无定义,8(x)具有x倒数的量纲,并且具有x算符本征函数的物理含意,澄清了量子力学教材中的一些模糊认识.     

Riccati-type Bcklund transformations of nonisospectral and generalized variable-coefficient KdV equations

We extend the method of constructing Bcklund transformations for integrable equations through Riccati equations to the nonisospectral and the variable-coefficient equations. By taking nonisospectral and generalized variable-coefficient Korteweg–de Vries(KdV) equations as examples, their B¨acklund transformations are obtained under a more generalized constrain condition. In addition, the Lax pairs and infinite numbers of conservation laws of these equations are given. Especially, some classical equations such as the cylindrical KdV equation are just the special cases of the constrain condition.     

5—Meng氧基—3,4—二取代丁烯内酯NMR的研究

报道了光学纯５－（１－Ｍｅｎｇ氧基）－３，４－二取代２（５Ｈ）－呋喃酮的＾１Ｈ ＮＭＲ和＾１３Ｃ ＮＭＲ数据，研究了不同取代基对结构以及核磁参数的影响。     

含δ势垒的铁磁/半导体/铁磁异质结中的自旋输运和渡越时间

研究了含δ势垒的铁磁/半导体/铁磁异质结中自旋相关的透射概率和渡越时间,讨论了量子尺寸效应和Rashba自旋轨道耦合效应对隧穿特性的影响.研究结果表明：δ势垒的存在降低了自旋电子的透射概率,改变了透射概率的位相.Rashba自旋轨道耦合强度的增加加大了透射概率的振荡频率.不同自旋取向的电子隧穿异质结时,渡越时间随着半导体长度、Rashba自旋轨道耦合强度以及两铁磁电极中的磁化方向的夹角的变化而变化. 关键词： δ势垒')" href="#">δ势垒 铁磁/半导体/铁磁异质结 Rashba自旋轨道耦合效应 渡越时间     

Dynamic Properties for a Single-mode Laser with δ-Correlation form Noises

By means of linear approximation method, we derive and discuss the intensity correlation function, correlation time, and power spectrum for the gain-noise model of a single-mode laser driven by multiplicative colored and additive white noises with δ-correlation form. It is found that: (1) The negative correlation between noises makes the evolution of the intensity correlation function with the time showing two forms: the monotonic attenuation and presence of the positive maximum value; while corresponding to all points on the critical line of the parameter graph for illustrating two forms, the evolution curve of the intensity correlation function with the time exhibits the initial plateau. (2) Due to the existence of the negative correlation between noises, an obvious character for the change of the intensity correlation time with the pump noise strength is that it has a crest value, and the relaxation process of the laser is slower-down than that of two independent noises. (3) The power spectrum exhibits only one peak.     

N-soliton solutions of an integrable equation studied by Qiao

In this paper, we studied N-soliton solutions of a new integrable equation studied by Qiao [J. Math. Phys. 48 082701 (2007)]. Firstly, we employed the Darboux matrix method to construct a Darboux transformation for the modified Korteweg-de Vries equation. Then we use the Darboux transformation and a transformation, introduced by Sakovich [J. Math. Phys. 52 023509 (2011)], to derive N-soliton solutions of the new integrable equation from the seed solution. In particular, the multiple soliton solutions are explicitly obtained and shown through some figures.     

Quantum percolation tunneling current 1/f~γ noise model for high-κ gate stacks Bi-layer breakdown

Based on the elastic trap-assisted tunneling mechanism in high-κgate stacks,a quantum percolation tunneling current 1/fγ noise model is proposed by incorporating quantum tunneling theory into the quantum percolation model.We conclude that the noise amplitude of the PSD(Power Spectral Density)for three stages,namely the fresh device,one-layer BD(breakdown),and two-layer BD,increases from 10-22→10-14→10-8 A2/Hz.Meanwhile,the noise exponent γ for the three stages,has the 1/f2type(γ→2),1/fγ type(γ→1~2),and 1/f type(γ→1),respectively.The simulation results are in good agreement with the experimental results.This model reasonably interprets the correlation between the bi-layer breakdown and the tunneling 1/fγ noise amplitude dependence and 1/fγ noise exponent dependence.These results provide a theoretical basis for the high-κ gate stacks bi-layer breakdown noise characterization methods.     

The form-invariance of wave equations without requiring a priori relations between field variables

According to the principle of relativity,the equations describing the laws of physics should have the same forms in all admissible frames of reference,i.e.,form-invariance is an intrinsic property of correct wave equations.However,so far in the design of metamaterials by transformation methods,the form-invariance is always proved by using certain relations between field variables before and after coordinate transformation.The main contribution of this paper is to give general proofs of form-invariance of electromagnetic,sound and elastic wave equations in the global Cartesian coordinate system without using any assumption of the relation between field variables.The results show that electromagnetic wave equations and sound wave equations are intrinsically form-invariant,but traditional elastodynamic equations are not.As a by-product,one can naturally obtain new elastodynamic equations in the time domain that are locally accurate to describe the elastic wave propagation in inhomogeneous media.The validity of these new equations is demonstrated by some numerical simulations of a perfect elastic wave rotator and an approximate elastic wave cloak.These findings are important for solving inverse scattering problems in many fields such as seismology,nondestructive evaluation and metamaterials.     

Teleportation of tripartite entangled coherent states

This paper proposes a feasible scheme for the quantum teleportation of tripartite entangled coherent states by using linear optical devices such as beam splitters, phase shifters and photo detectors. The scheme is based on the bipartite maximally entangled coherent state and the tripartite entangled coherent state with bipartite maximal entanglement as quantum channels. It shows that when the mean number of photons is equal to 2, the total minimum of the average fidelity for an arbitrary tripartite entangled state is 1-0.67×10 ^-3.     

Abundant exact solutions for a strong dispersion-managed system equation

The generalized nonlinear Schr?dinger equation (NLSE), which governs the dynamics of dispersion-managed (DM) solitons, is considered. A novel transformation is constructed such that the DM fibre system equation with optical loss (gain) is transformed to the standard NLSE under a restricted condition. Abundant new soliton and periodic wave solutions are obtained by using the transformation and the solutions of standard NLSE. Further, we discuss their main properties and the interaction scenario between two neighbouring solitons by using direct computer simulation.     

辐射传输中的相函数展开方法研究

从辐射传输方程中相函数的展开方法出发,分别介绍了δ-M展开法和δ-fit展开法,并对这两种相函数展开方法进行了比较。结果表明,在相函数展开中,当所取勒让德多项式的阶数相同时,δ-M法的图像始终在真实相函数附近波动,始终无法逼近真实的相函数的值,而δ-fit法符合较好。     

Effects of pre-deformation on the martensitic transformation and magnetocaloric property in Ni-Mn-Co-Sn ribbons

This paper investigates the martensitic transformation and magnetocaloric effect in pre-deformed Ni-Mn-Co-Sn ribbons.The experimental results show that the reverse martensitic transformation temperature T M increases with the increasing pre-pressure,suggesting that pre-deformation is another effective way to adjust T M in ferromagnetic shape memory alloys.Large magnetic entropy changes and refrigerant capacities are obtained in these ribbons as well.It also discusses the origin of the enhanced martensitic transformation temperature and magnetocaloric property in pre-deformed Ni-Mn-Co-Sn ribbons.