Short range order transformation and magnetostriction of Fes3Ga17 ribbons

The relationship between magnetostriction and structure of melt-spun Fes3Ga17 ribbons are investigated by XRD and M5ssbauer spectrum technique （MS）. As the heat-treatment temperature increases from 650℃ to 800℃, the magnetostriction coefficient of Fes3Ga17 ribbon first increases and then decreases. The largest magnetostriction coeiffcient （-578.4 ppm） is achieved in those specimens quenched at 750oc. According to the XRD and MSssbauer spectrum anal- ysis, a small quantity of DO3 phase is precipitated in Fe83Ga17 ribbons when quenched from 650℃ and the DO3 phase is gradually transformed into B2-1ike phase if quenched at higher temperature. However, both DO3 and B2-1ike phases disappear when the temperature increases up to 800℃. From this point of view, B2-1ike phase might be beneficial to the enhancement of magnetostrictive properties of melt-spun ribbons.     

Pr0．45（Ca1-xSrx）0．55MnO3体系调带宽引起的磁相变及电输运性质转变

采用固相法制备了Pr0．45（Ca1-xSrx）0．55MnO3（x=0．0,0．2,0．4,0．6,0．8,1．0）多晶样品．通过测量样品的X射线衍射（XRD）谱、磁化强度-温度（M～T）曲线、电阻率-温度（ρ～T）曲线,研究了Sr^2＋替代Ca^2＋对Pr0．45Ca0．55MnO3体系磁性和电性的影响．实验发现：...     

不同厚度的活性层及阴极的改变对聚合物太阳电池性能的影响

以MEH-PPV(poly(2-methoxy-5-(2'-ethylhexoxy)-1,4-phenylene vinylene))为电子给体材料, PCBM(1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6)C₆₁)为电子受体材料, 制成了共混体系太阳电池.研究了不同厚度活性层对太阳电池性能的影响.结果表明, 活性层厚度为100 nm时,太阳电池具有最佳性能.活性层厚度的增加,增大了光生电荷的复合,减少了太阳电池的填充因子,从而减少了太阳电 关键词： 太阳电池 厚度 电极 性能     

Analysis of ultrasonic guided waves propagating in long bones and cortical thickness based on time-frequency methods

The ultrasonic signals in long bones contain multiple guided modes which are mutual superposed.The velocities of guided waves in long bones are very sensitive to cortical thickness (CTh).In this paper,Hilbert-Huang transform(HHT) was proposed to analyze multi-mode guided waves,which can decompose superposed waves into many independent modes.Then the group velocity of each mode was obtained at corresponding frequency,which was compared with the results of short time Fourier transform(STFT).The CTh was also obtained by comparing with the theoretical calculation.The results showed that the experimental determined thickness was in agreement with the actual CTh,indicating that measuring the velocity of the guided mode can be used to estimate the CTh.The HHT is an effective method to identify multimode guided waves.     

A new probe of neutron skin thickness

The correlation between neutron-to-proton yield ratio (R_np) and neutron skin thickness (δ_np) in neutron-rich projectile induced reactions is investigated within the framework of the Isospin-Dependent Quantum Molecular Dynamics (IQMD) model. The density distribution of the Droplet model is embedded in the initialization of the neutron and proton densities in the present IQMD model. By adjusting the diffuseness parameter of neutron density in the Droplet model for the projectile, the relationship between the neutron skin thickness and the corresponding R_np is obtained. The results show strong linear correlation between R_np and δ_np for neutron-rich Ca and Ni isotopes. It is suggested that R_np may be used as an experimental observable to extract δ_np for neutron-rich nuclei, which is very interesting in the study of the nuclear structure of exotic nuclei, the equation of state (EOS) of asymmetric nuclear matter and neutron-rich matter in astrophysics, etc.     

梯度磁场中薄膜厚度梯度的形成机理

借助于基片下方放置的磁铁，在溅射的放电空间中引入了纵向的梯度磁场，辉光放电时，其外貌发生了显著的收缩，由此沉积的薄膜在平面内存在明显的厚度梯度，用磁场中带电粒子的运动理论解释了此种薄膜的形成机制。     

试论数学教学中的启发

在几乎所有数学教育、教学研究的论文、论著中,我们都会发现关于"启发"的论述.为了语言的生动、词汇的丰富,也经常能看到"启发"的同义词或近义词,如"提示、启导、引导、诱导、点拨"等.随着新课程改革的不断深入,中学数学教育界对"启发"的探究也在不断地深化.可另一方面,由于升学的巨大     

半导体激光器M^2因子可以小于1

根据Porras的非傍轴矢量矩理论，对双异质结半导体激光器的光束质量进行了研究，结果表明，在有源层厚度da远小于波长λ的条件下，半导体激光器的M62因子可以小于1，并且没有下限。     

Geometry optimization in planetary rotation stage for thickness uniformity of films on spherical substrates

We report the simulation results on the thickness uniformity of optical coatings deposited on spherical substrates by optimizing the geometric configuration parameters, such as tilting angle of the substrate holder and position of the evaporation source in a 1 000-mm-diameter planetary rotation stage （PRS）. We reveal that good film uniformity on convex spherical surfaces or flat substrates, as well as concave surfaces with weak to moderate curvatures can be obtained through appropriate tilting of the substrate holder. For 300-mm-diameter substrates with clear aperture to radius of curvature （CA/RoC） between 0.3 and 0.7, the achievable film uniformity is above 99%. The source position is optimized to achieve good film uniformity.     

Method to accurate calibrate deposition rates of EUV multilayer coatings

Random thickness error is an important factor which effects the calibration accuracies of deposition rates for extreme ultraviolet （EUV） multilayer coatings fabricated by sputter deposition techniques. A least square fitting method is proposed to determine deposition rates and extract random thickness errors accurately. The validity of this method is shown by evaluating two deposition systems with control abilities of -0.1 nm and better than 0.01 nm respectively.