CRITICAL CURRENT DENSITY OF Y-Ba-Cu-Sn-O SUPERCONDUCTORS

The magnetic curves of bulk Y-Ba-Cu-Sn-O have been studied in the temperature range 60-77K and in fields up to 2.4T. The results indicate that J_c varies with the magnetic field as a power law and decreases exponentially with temperature. The critical current density J_c can be improved by the substitution of Sn for Cu.     

Yba2Cu3O7-δ不可逆线与钉扎势的关联

本文分别测量了熔融织构YBa₂Cu₃O_7-δ高温超导体不可逆线与钉扎势U₀,发现该样品的不可逆线在温区72—85K范围内呈指数形式B^*-e^(-T*/T_c)函数关系,而且在温度77K,不可逆线并不能与磁测量临界电流密度J_c=0相对应,我们认为高温超导体的不可逆线的函数形式与样品的钉扎势紧密关联。 关键词：     

Characterization of tetragonal distortion in a thick Al_(0.2)Ga_(0.8)N epilayer with an AlN interlayer by Rutherford backscattering/channeling

An Al0.2Ga0.8N/AlN/Al0.2Ga0.8N heterostructure was grown by metalorganic chemical vapor deposition on a sapphire(0001) substrate with a thick(> 1 μm) GaN intermediate layer. The Al composition was determined by Rutherford backscattering(RBS). Using the channeling scan around an off-normal [1213] axis in the(1010) plane of the Al0.2Ga0.8N layer, the tetragonal distortion eT, which is caused by the elastic strain in the epilayer, is investigated. The results show that eTin the high-quality Al0.2Ga0.8N layer is dramatically released by the AlN interlayer from 0.66% to 0.27%.     

Banach空间中伪压缩映象不动点的迭代逼近

Let K be a nonempty closed convex subset of a real p-uniformly convex Banach space E and T be a Lipschitz pseudocontractive self-mapping of K with F(T) := {x ∈K : Tx=x}≠φ.Let a sequence {xn} be generated from x1 ∈K by xn 1 = αnxn bnTyn сnun,yn=a'nxn b'nTxn c'nun for all integers n≥1.Then ‖-Txn‖→0 as n→∞.Moreover,if T is completely continuous,then {xn}converges strongly to a fixed point of T.     

牛顿环测透镜曲率半径数据分析和结果探讨

文中用Origin软件对牛顿环实验的数据进行线性拟合与处理,具有简洁、快捷与直观等特点.并讨论了所得拟合曲线的截距与牛顿环实验装置的关系.     

Preoaration of a Pd-Cu-Si Bulk Metallic Glass with a Diameter up to 11 mm

Pd77.5 Cu6Si16.5 （at.%） bulk metallic glass with a diameter up to 11 mm was successfully fabricated by water quenching method together with melt purification. By using x-ray diffraction and transmission electron microscopy techniques, the structure of the as-prepared sample is confirmed to be glassy. The resulted sample with 11 mm diameter indicates that the melt purification by fluxing method can effectively enhance the glass forming ability of Pd-Cu-Si alloy, and increase its critical size of glassy sample.     

新型五甲川吡喃鎓盐染料的合成及锁模性能

合成了６ 种五甲川吡喃鎓盐染料，通过红外光谱、核磁共振氢谱及元素分析确证了其结构． 研究了其电子吸收光谱及其在Ｎｄ３ ＋ ：ＹＡＧ激光器上的锁模性能． 结果表明，染料在１ ，２二氯乙烷溶液里最大吸收波长在１０５２ ～１０９５ ｎｍ 之间，６ 个染料全部锁模成功，脉宽为２８ ～３５ ｐｓ，锁模情况比镍络硫代双烯型染料ＢＤＮ 好．     

渐近伪压缩和渐近非扩张映像不动点的迭代逼近问题

研究了Banach空间中渐近伪压缩和渐近非扩张映像不动点的迭代逼近问题,改进和发展了张石生教授等人的相应结果.