聚合物边孔封装无源光纤光栅水听器

报道了一种聚合物边孔封装的无源光纤光栅水听器的研究结果.采用边孔封装结构对裸光纤光栅进行了增敏封装,其静态压力灵敏度提高了17120倍,为光纤光栅的水声探测奠定了物理基础;利用可调谐窄带光源的线宽窄和其波长可调谐的特点,采用带工作点控制的强度调制方案进行信号解调,不仅实现了高精度的动态信号检测,并解决了温度变化对系统影响的问题.实验测量结果表明,所设计的光纤光栅水听器在500Hz频率处的声压灵敏度为-153.3 dB(0 dB=1 pm/μPa),且具有非常好的各向同性指向性,其最小可测声压为61 dB(0 dB=1 μPa/√Hz).     

Experimental constraints on the phase diagram of titanium metal

The phase transformations of titanium metal have been studied at temperatures and pressures up to 973 K and 8.7 GPa using synchrotron X-ray diffraction. The equilibrium phase boundary of the α-ω transition has a dT/dP slope of 345 K/GPa, and the transition pressure at room temperature is located at 5.7 GPa. The volume change across the α-ω transition is ΔV=0.197 cm³/mol, and the associated entropy change is ΔS=0.57 J/mol K. Except for ΔV, our results differ substantially from those of previous studies based on an equilibrium transition pressure of 2.0 GPa at room temperature. The α-ω-β triple point is estimated to be at 7.5 GPa and 913 K, which is comparable with previous results obtained from differential thermal analysis and resistometric measurements. An update, more accurate phase diagram is established for Ti metal based on the present observations and previous constraints on the α-β and ω-β phase boundaries.     

60Coγ和高能电子在硅中NIEL的Monte Carlo计算

本文提出了计算高能电子和γ非电离能量损失(NIEL)的Monte Carlo方法,首次利用Monte Carlo方法计算了高能电子和⁶⁰Coγ的NIEL.给出了电子和⁶⁰Coγ在半导体硅材料中产生的NIEL和缺陷分布.计算结果与文献的比较表明模型是合理的.     

Asymptotic bounds for some bipartite graph: complete graph Ramsey numbers

The Ramsey number r(H,K_n) is the smallest integer N so that each graph on N vertices that fails to contain H as a subgraph has independence number at least n. It is shown that r(K_2,m,K_n)(m−1+o(1))(n/log n)² and r(C_2m,K_n)c(n/log n)^m/(m−1) for m fixed and n→∞. Also r(K_2,n,K_n)=Θ(n³/log² n) and .     

助剂对氨合成Fe1-xO基催化剂母体歧化反应的抑制作用的穆斯堡尔谱研究

Fe1-xO基氨合成催化剂具有高活性、易还原的特点[1,2].但Fe1-xO基催化剂的母体Fe1-xO在570℃以下热力学上的不稳定性是Fe1-xO基催化剂使用过程中倍受关注的重要问题之一.     

固溶体α－(Fe1－χSbχ)2O3(0≤χ≤0.2)气敏材料

用化学共沉淀法在α-Fe₂O₃,中掺入锑离子,X-射线衍射(XRD)分析证实,锑离子可固溶于n型半导体α-Fe₂O₃中形成α－(Fe_1－χSb_χ)₂O₃(0≤χ≤02)固溶体。由于锑离子(Sb⁵⁺)部分取代α-Fe₂O₃晶格中Fe³⁺的格位,使得该系列材料的电导值增大一个数量级以上,气敏性能明显改善。     

Studies on Solid-Liquid Phase Transfer Equilibrium of Onium Salts(Ⅱ)

The present paper contains the effects of the ammonium ion, counter ion, solvent and anion being transferred on the solid-liquid phase transfer equilibrium constant of quaternary ammonium salts. The most striking difference between solid-liquid and liquid-liquid phase transfer equilibriums is that the length of alkyl chain shows a large effect on the latter but little on the former This means that the chain length affects only the hydrophobicity, rather than the lipophilicity.Keywords Quaternary ammonium salt, Phase transfer catalysis, Equilibrium constant, Hydrophobicity, Lipophilicity     

离子对的聚集作用(Ⅲ)——不同负离子对聚集度的影响

相转移催化方法是现代有机合成的新方法之一。目前,在实验室和工业生产上都有广泛的应用。其中一种重要的催化剂就是鎓盐,因此,鎓盐在有机溶剂中的聚集状态、聚集数目(聚集度)的不同,以及与反应性能的关系是值得探讨的基本课题之一。近年来,国外开展了有关的研究工作,但其结果尚有争议。     

离子对的聚集作用(Ⅰ)——溶剂和卤负离子对聚集度的影响

用沸点升高法测定了卤化四丁铵在有机溶剂中的平均聚集度。发现溴化四丁铵在苯中的聚集度远大于在氯仿中的。说明溶剂的极性起着首要作用。在氯仿中聚集度的大小顺序为碘化四丁铵>溴化四丁铵>氰化四丁铵。 还测定了溴化与碘化四丁铵混合溶液的聚集度。测得值显著大于它们单独存在时的值。认为存在离子对的渔合聚集体。     

一、二维弹塑性流体动力学数值计算的高精度新自由面格式

提出了适用于X射线或电子束辐照、爆炸和高速碰撞等问题的一、二维弹塑性流体动力学数值模拟计算的一种新自由面格式。对于X射线及电子束辐照材料与结构的热-力学效应的数值计算结果表明,该新自由面格式明显优于目前一直沿用的Richtmyer格式。从理论上证明了该新自由面格式具有三阶精度,而Richtmyer格式为一阶精度。