YBa2Cu3O7—x和GdBa2Cu3O7—x薄膜中的涡旋玻璃转变的观察

本给出了具有高密度孪晶界ｃ取向ＹＢａ２Ｃｕ３Ｏ７－ｘ外延薄膜存在涡旋玻璃转变及很好的标度行为的实验证据，在有ａ方向昌粒或４５°晶界的ＧｄＢａ２Ｃｕ３Ｏ７－ｘ外延薄膜中存在涡旋玻璃转变但在转变温度附近观察到磁通蠕动和热激活磁通流的某些特征。     

超临界二氧化碳在高分子合成及加工领域的应用

重点概述了近年来超临界二氧化碳作为环境友好介质在高分子合成与加工方面研究的新进展,具体介绍了在超临界二氧化碳中丙烯酸的合成及疏水改性方面所做的工作,并在此基础上,展望超临界二氧化碳作为高分子合成介质的前景。     

微胶囊技术及其在相变材料中的应用

微胶囊技术因其独特的功能而得到广泛的应用。微胶囊相变材料是将微胶囊技术应用到相变材料中而形成的新型复合相变材料。文章介绍了微胶囊技术及其功能,重点论述了微胶囊相变材料及其结构组成、制备方法、研究进展和应用领域,并对其发展前景进行了展望。     

成灰温度对准东煤灰理化特性影响的实验研究

将3种新疆准东煤和4种对比煤种在不同温度下制灰,研究了成灰温度对灰理化特性的影响,并分析了准东煤的积灰结渣特性。研究表明:灰分量、灰成分、灰熔融性、灰挥发特性均与成灰温度密切相关,成灰温度过高会导致碱金属挥发,过低则灰中含有可燃成分。过高或过低的成灰温度均不能准确反映准东煤灰的理化特性,655℃成灰温度比较适合准东煤.提出了采用ST与碱金属含量相结合的结渣判定方法,提高了准东煤结渣判别的准确性.     

乳化沥青及其乳化剂的发展与应用

概述了国内外乳化沥青及其乳化剂在建筑防水、道路维修养护等领域的应用概况,着重论述了乳化剂的分类、选择方法以及乳化剂复配体系的应用情况。根据我国的现状,指出了乳化沥青的高性能化、沥青乳化剂多样化将是主要的发展方向。     

YBa_2Cu_3O_（7－x）和GdBa_2Cu_3O_（7－x）薄膜中涡旋

本文给出了具有高密度孪晶界ｃ取向ＹＢａ２Ｃｕ３Ｏ７－ｘ外延薄膜存在涡旋玻璃转变及很好的标度行为的实验证据．在有α方向晶粒或４５°晶界的ＧｄＢａ２Ｃｕ３Ｏ７－ｘ外延薄膜中存在涡旋玻璃转变但在转变温度附近观察到磁通蠕动和热激活磁通流动的某些特征．这些结果可以在涡旋玻璃理论，Ａｎｄｅｒｓｏｎ－Ｋｉｍ磁通蠕动模型以及热激活磁通流动模型框架内给于很好的解释．     

FLUX CREEP, FLUX PINNING AND CRITICAL CURRENT DENSITY OF Y-, Gd-, AND Tl-BASED SUPERCONDUCTIVE THIN FILMS

Magnetic hysteresis loops have been measured for YBa₂Cu₃O_6+x, GdBa₂Cu₃O_6+x and Tl₂Ba₂Ca₂Cu₃O_10-y films at different temperatures with a vibrating sample magnetometer. Based on Bean model, magnetic critical current density J_cm has been derived approximately. The field and temperature dependence of J_cm for all samples can be written as: J_cm= J_c0(T)×f(B,T), Where f(B,T) = 1 - Aln(B/B₀(T)), which is similar to the transport critical density strongly affected by flux creep: J_ct = J_c0(B,t)(1 - (k_BT/U₀)ln(BΩd/E_c)). The extraordinary similarity suggests that J_cm is determined not only by flux pinning but also by flux creep. In the first formula, f(B,T) may be correlated with the effect of flux creep on J_cm, and J_c0(T) is determined by flux pinning. J_c0(T) is independent of magnetic field and is proportional to (T_c - T). Similar results have also been found for other samples. It may be the common characteristic of high-T_c superconductors. Magnetic relaxation of YBa₂Cu₃O_6+x and GdBa₂Cu₃O_6+x films has been measured at LN₂ temperature. Using the equation of Hagen et al., effective activation energy U₀ has been deduced, which is about 0.3eV, one order bigger than the value obtained by A = k_BT/U₀. U₀ is almost independent of the field in the field range selected.     

某型陀螺仪自然贮存寿命评估与加速寿命试验时间预估

某型陀螺仪是影响武器控制舱贮存寿命的薄弱环节,针对历年统计的陀螺仪的成败型、不完全故障数据,将"保序回归"和"变样本Pearson?2拟合优度检验与极小卡方估计"相结合,得到了其寿命分布函数。结果显示,I型极大值和威布尔分布适用于陀螺仪的寿命分布,但I型极大值不具有可加速性,因而选择威布尔分布作为寿命分布。根据统计数据计算,得到了置信度0.90和可靠度0.95时陀螺仪自然贮存寿命为22.30年,得到了陀螺仪在90℃下的加速系数K=7.2695,预估了2009年和2011年生产的陀螺仪加速寿命试验时间分别为8.25月和11.56月,对加速寿命试验时间规划、经费预算具有工程实际意义。     

Strain-induced insulator–metal transition in ferroelectric BaTiO_3(001) surface:First-principles study

The electronic properties of TiO_2-terminated BaTiO_3(001) surface subjected to biaxial strain have been studied using first-principles calculations based on density functional theory. The Ti ions are always inward shifted either at compressive or tension strains, while the inward shift of the Ba ions occurs only for high compressive strain, implying an enhanced electric dipole moment in the case of high compressive strain. In particular, an insulator–metal transition is predicted at a compressive biaxial strain of 0.0475. These changes present a very interesting possibility for engineering the electronic properties of ferroelectric BaTiO_3(001) surface.     

无卤磷系阻燃聚合物研究进展

无卤磷系阻燃聚合物燃烧时低烟无毒,对环境污染少,阻燃剂含量较少就能达到好的阻燃效果,且对聚合物材料的各种性能影响甚微,因而无卤磷系阻燃聚合物得到广泛的应用。文中在参考了大量文献的基础上,对无卤磷系阻燃聚合物的合成、结构、性能及应用做了详细的介绍和论述,并展望了无卤磷系阻燃聚合物的发展方向和前景。