Experimental Investigation of Tm3＋-Doped Silica Double-Cladding Fibre Laser

Using a Tm^3＋-doped double-cladding silica fibre, we produce a maximum cw 2.2 W output at approximately 2μm. The highest achieved slope efficiency is 29.3% respect to the launched pump power. The lowest threshold is 1.85 W using the double pass pump method with the fibre length 2. 7m, which is the lowest reported threshold of cladding pump of the ^3H4 level. The fibre laser output peak wavelength ranges from 1.967μm to 2.018μm with cavity 1 （R1 = 1 and R2=0.04） and from 1.95μm to 1.99μm with cavity 2 （R1=0.04 and R2=0.04）, as the fibre length varies.     

Structures of Adatom Clusters on Ag（111） Surface by Genetic Algorithm

We study the structures of Ag adatom clusters supported on the metal Ag(111) surface using the genetic algorithm (GA). The atomic interactions are modelled by the surface-embedded-atom method. The lowest-energy structures of adatom clusters with sizes n=3-20 are obtained, in which n=7, 10, 12, 14, 16, 19 are the magic numbers. Furthermore, we give a series of structures with energies close to the lowest energy (the lower-energy isomers), and the structure features are studied in detail. Except for some magic clusters and small clusters, every configuration of adatom clusters generally has two distinct adsorption ways, so the isomers always appear in pairs.     

宏观－微观模型对奇－偶超重核基态性质的系统研究

用宏观－微观模型系统计算了Z=95—113奇－偶超重核的基态性质. 理论计算的结合能、α衰变能与已知的实验数据符合较好, 也与相对论平均场的计算结果符合很好, 这进一步肯定了宏观－微观模型对超重核研究的可靠性. 理论计算表明形变对超重核的性质起重要作用. 同时, 对一些未知核素基态性质的预言可为将来的实验研究提供理论参考.     

非均匀介质的驻波演示及分析

本文给出利用特制弹簧和扬声器等材料，介绍了课堂用的均匀介质和课外探索用的非均匀介质演示仪的制作和分析。     

Entanglement in the supermolecular dimer [Mn4]2

This paper investigates the entanglement in the supermolecular dimer [Mn4]2 consisting of a pair of single molecular magnets with antiferromagnetic exchange-coupllng J. The conventional yon Neumann entropy as a function of the exchange-coupling is calculated explicitly for all eigenstates with the quantum number range from M = M1 ＋ M2 = -9 to 0. It is shown that the yon Neumann entropy is not a monotonic function of the coupling strength. However, it is significant that the entropy of entanglement has the maximum values and the minimum values for most eigenstates, which is extremely useful in the quantum computing. It also presents the time-evolution of entanglement from various initial states. The results are useful in the design of devices based on the entanglement of two molecular magnets.     

定身加准基数的应用

定身加是种古老的算法，我们把这种古老的算法应用到现代珠算，来个珠脑结合，有许多数字相乘，根本用不着逐位实乘，只凭眼看用心脑算，就可很快得出答数来。方法就是定身加准基数。首先我们要了解，什么是准基数呢，凡两数相乘，如能利用数与数之间的特殊关系，利用数的运算规律和数的性质，采用     

循环荷载作用下聚丙烯纤维再生混凝土受压性能试验研究

为研究循环荷载作用下聚丙烯纤维再生混凝土(PFRAC)的力学性能，以粗骨料取代率、纤维掺量、加载速率为变化参数，设计了78个圆柱体试件进行单轴循环受压试验。通过试验观察PFRAC的破坏形态，获取了应力-应变曲线、峰值应力、峰值应变、刚度退化等重要指标，研究了不同变化参数对其力学性能指标的影响规律，得到了循环荷载作用下聚丙烯纤维对再生混凝土的阻裂机理。结果表明：循环荷载作用下PFRAC主要发生斜向劈裂破坏；随着聚丙烯纤维掺量的增加，试件表面主裂缝宽度减小；循环荷载下PFRAC试件受压应力-应变曲线包络线与单调受压应力-应变曲线相似；聚丙烯纤维的加入可显著改善PFRAC循环荷载下的力学性能，随着纤维掺量的增加，峰值应力、弹性刚度比先增大后减小；纤维掺量为0.9%时的纤维改性效果最优，峰值应力和峰值刚度比分别提高了4.4%和7.4%。     

Influence of Positive Bias on Electrical Properties of Undoped Nanocrystalline Diamond Films

By means of electron assisted hot filament chemical vapour deposition technology, nanocrystalline diamond films are deposited on polished n-（100）Si wafer surface at I kPa gas pressure. The deposited films are characterized with a Raman spectrometer, atomic force microscope, semiconductor characterization system and Hall effect measurement system. The results show that, when bias current is larger than 2 A, sheet hole concentration can increase to a value greater than 1013 cm-2 and undoped nanocrystalline diamond films with a p-type semiconducting characteristic form. Heterojunction between n-Si substrate and the nanocrystalline diamond films deposited with 2 A and 6 A bias current has an evident junction effect. Hole formation mechanisms in the films are discussed.     

脉冲管制冷机中惯性管的数值模拟研究

本文利用Fluent软件对惯性管进行数值模拟,计算采用二维层流的数值模型,得到惯性管入口处质量流量与压力波之间的相位及惯性管内部的压力波幅值和质量流量幅值的变化,给出不同频率及惯性管尺寸对惯性管入口处压力波与质量流量之间的相位的影响.通过分析并计算得到脉冲管冷端质量流量,进行设计计算.     

对角形椭圆型方程组的解的Liouville定理

考虑对角型椭圆组=f_i(x,u,(?)u),i=1,2,…,N. 对一种特殊情形证明其广义解的Liouville型定理成立.