Asymmetric W-shaped and M-shaped soliton pulse generated from a weak modulation in an exponential dispersion decreasing fiber

We study localized waves on continuous wave background in an exponential dispersion decreasing fiber with two orthogonal polarization states. We demonstrate that asymmetric W-shaped and M-shaped soliton pulse can be generated from a weak modulation on continuous wave background. The numerical simulation results indicate that the generated asymmetric soliton pulses are robust against small noise or perturbation. In particular, the asymmetric degree of the asymmetric soliton pulse can be effectively controlled by changing the relative frequency of the two components. This character can be used to generate other nonlinear localized waves, such as dark–antidark and antidark–dark soliton pulse pair, symmetric W-shaped and M-shaped soliton pulse. Furthermore, we find that the asymmetric soliton pulse possesses an asymmetric discontinuous spectrum.     

基于连续激光的纳米结构研制

基于激光受激辐射损耗原理的远场光学超分辨成像技术,当圆形入射高斯激光经过涡旋相位板调制后,将转变为中心光强为零的圆环形光束,该形状的激光束与光敏聚合物作用,能够制备出具有一定功能的纳米结构。介绍了自主搭建的基于圆环连续激光光源的激光直写系统,以及利用该系统研制的复合纳米结构。当光源为532 nm连续激光输出时,与正性光刻胶作用,得到直径 < 50 nm的纳米柱复合结构,以及整齐均匀的纳米柱阵列结构;与负性光刻胶作用,得到直径 < 100 nm的纳米通道,以及整齐均匀的中央有纳米通道的微米柱复合结构阵列。当光源为405 nm连续光纤激光时,与正性光刻胶作用,也得到了直径小至153 nm的纳米柱复合结构及其阵列。这些纳米结构的基本单元尺寸都突破了光学“阿贝衍射极限”的限制,具有实用潜力。     

Cu掺杂对TiNi合金马氏体相变路径影响的第一性原理研究

不同浓度的Cu元素掺杂会极大地影响TiNi二元合金的物理性质和相变行为.为了解释其中的物理机制,本文通过第一性原理计算,对TiNi和Ti_(50)Ni_(25)Cu_(25)的相变机制和相稳定性进行了计算和讨论.通过计算Cu掺杂前后立方相到正交相、再到单斜相过程中的相变路径和相变势垒,解释了Cu掺杂对二元合金TiNi相变过程的影响.计算结果表明:TiNi合金的正交相和单斜相之间存在一个大小为1.6meV的相变势垒;而对于Ti_(50)Ni_(25)Cu_(25),这两个相之间的相变势垒大小至少为10.3meV,如此大的一个相变势垒意味着Ti_(50)Ni_(25)Cu_(25)合金的正交相很难跨过势垒相变到单斜相.     

N-(乙氧酰基)-N’-(2,4-二硝基苯胺基)硫脲的合成、晶体结构、比热容及热力学性质

以PEG-400为催化剂,利用氯甲酸乙酯和硫氰酸钾反应生成的乙氧酰基异硫氰酸酯为中间体与2,4-二-硝基苯肼反应,得到N-(乙氧酰基)-N′-(2,4-二硝基苯胺基)硫脲,通过IR、元素分析等方法对其结构进行了表征。 在室温条件下,采用缓慢挥发法培养出适合用于X射线衍射测试的单晶。 晶体结构数据表明,晶体属单斜系,P2(1)/c空间群,晶胞参数:a=4.1919(2) nm,b=12.295(6) nm,c=23.828(11) nm,α=γ=90.00°,β=92.467(10)°,V=14397(12),Dc=1.519 g/cm3,μ=0.263 cm-1,F(000)=680,Z=4,R1=0.1121,wR2=0.2540。 并对标题化合物进行了热重分析和比热容测定,计算了热力学函数;证明该化合物有良好的热稳定性。     

Flow structure and bubble dynamics in supercritical water fluidized bed and gas fluidized bed: A comparative study

Supercritical water (SCW) fluidized bed is a new reactor concept for hydrogen production from biomass or coal gasification. In this paper, a comparative study on flow structure and bubble dynamics in a supercritical water fluidized bed and a gas fluidized bed was carried out using the discrete element method (DEM). The results show that supercritical water condition reduces the incipient fluidization velocity, changes regime transitions, i.e. a homogeneous fluidization was observed when the superficial velocity is in the range of the minimum fluidization velocity and minimum bubbling velocity even the solids behave as Geldart B powders in the gas fluidized bed. Bubbling fluidization in the supercritical water fluidized bed was formed after superficial velocity exceeds the minimum bubbling velocity, as in the gas fluidized bed. Bubble is one of the most important features in fluidized bed, which is also the emphasis in this paper. Bubble growth was effectively suppressed in the supercritical water fluidized bed, which resulted in a more uniform flow structure. By analyzing a large number of bubbles, bubble dynamic characteristics such as diameter distribution, frequency, rising path and so on, were obtained. It is found that bubble dynamic characteristics in the supercritical water fluidized bed differ a lot from that in the gas fluidized bed, and there is a better fluidization quality induced by the bubble dynamics in the supercritical water fluidized bed.     

多模叠加态|Ψe4,Ⅲ〉q中广义电场分量的N次方H压缩

利用多模压缩态理论,详细研究了由多模偶相干态和多模虚偶相干态的线性叠加所组成的一种新型的四态叠加多模叠加态光场|Ψ_e⁴,Ⅲ〉_q中广义电场分量的等幂次N次方H压缩特性结果表明:1)在腔模总数q与压缩次数N的乘积q·N=4m(m=1,2,3,…)的条件下,态|Ψ_e⁴,Ⅲ〉_q的广义电场分量可恒处于等幂次NH最小测不准态2)在q·N=4m’+2(m’=0,1,2,…)的条件下,当态间的初始相位差(θ₁-θ₂)、各模的初始相位和 φ_j,以及各模平均光子数之总和 R_j²等分别满足一定的取值条件时,态|Ψ_e⁴,Ⅲ〉_q的广义电场分量总可呈现出周期性变化的偶数次的等幂次N次方H压缩效应.     

Scheduling sports competitions at multiple venues—Revisited

In this work, we study scheduling sports competitions at multiple venues, a problem recently introduced by Urban and Russell [T.L. Urban, R.A. Russell, Scheduling sports competitions on multiple venues, European Journal of Operational Research 148 (2003) 302–311]. The distinguishing feature of the problem is that venues come into play when scheduling. We develop beam search and simulated annealing approaches to the problem and its extension. Computational experiments were conducted and algorithms compared and analyzed. We found that the simulated annealing algorithm with specialized neighborhood moves achieved superior solutions in significantly shorter times than the method of Urban and Russell.     

On a Problem of D. H. Lehmer

The main purpose of this paper is to use the Fourier expansion for character sums and the mean value theorem of Dirichlet L-functions to study the asymptotic property of the difference between a D. H. Lehmer number and its inverse modulo p （an odd prime）, A interesting mean square value formula is also given.     

Thermal decomposition of Pr[(C5H8NS2)(C12H8N2)]

The thermal behavior of the complex Pr[(C₅H₈NS₂)(C₁₂H₈N₂)] in a dry nitrogen flow was examined by TG-DTG analysis. The TG-DTG investigations indicated that Pr[(C₅H₈NS₂)(C₁₂H₈N₂)] was decomposed into Pr₂S₃ and deposited carbon in one step where Pr₂S₃ predominated in the final products. The results of non-isothermal kinetic calculations showed that the decomposition stage was the random nucleation and subsequent growth mechanism(n = 2/3), the corresponding apparent activation energyE was 115.89 kJ•mol⁻¹ and the pre-exponential constant In[A/s] was 7.8697. The empirical kinetics model equation was proposed as\(f(\alpha ) = \frac{3}{2}(1 - \alpha )[ - 1n(1 - \alpha )]^{\frac{1}{3}} \). The X-ray powder diffraction patterns of the thermal decomposition products at 800 °C under N₂ atmosphere show that the product can be indexed to the cubic Pr₂S₃ phase. The transmission electron microscopy (TEM) of the final product reveals the particle appearance of a diameter within 40 nm. The experimental results show that the praseodymium sulfide nanocrystal can be prepared from thermal decomposition of Pr[(C₅H₈NS₂)(C₁₂H₈N₂)].

     

核壳型二氧化硅色谱填料的研究进展

复杂样品的高效快速分离分析是分离科学家所面临的挑战。近年来,核壳型二氧化硅色谱填料以其高效、快速和低背压的特点被广泛用于小分子、大分子和复杂样品的快速分离分析。该文系统综述了二氧化硅核壳色谱固定相快速分离的机理,制备方法及其在小分子、多肽和生物大分子快速分离分析方面的应用,同时对核壳型色谱固定相的发展进行了展望。