Low temperature synthesis of aluminium titanate by an aqueous sol-gel route

Formation of aluminium titanate (AT) has been achieved at low temperature through sol-gel process using boehmite and titanium hydroxide as precursors by controlling the particle size at nanoscale followed by in-situ peptisation. The formations of AT phase, particle size distributions, sintering and thermal expansion characteristics, and microstructural features have been reported. DTA and XRD analysis have been performed to confirm the formation of AT. A 94% relative density was obtained for aluminium titanate sintered at 1550 °C with controlled grain size in the range of 2-3 μm.     

一种新的变步长ICA自适应算法

结合互信息极小的优化判据，基于估计函数期望平方准则、外点法和最速下降法的思想，本文导出了一种新的变步长独立分量分析(ICA)自适应算法。该算法克服了固定步长在分离矩阵推导过程中出现的稳态失调问题，比基于模拟退火步长的ICA算法有更快的仞始收敛速度和较高的分离精度。同时，该算法还具有较好的时变系统跟踪能力。理论分析和仿真计算结果证实了其可以有效地提高ICA的自适虚性，更准确地完成盲信号分离。     

核磁共振谱的岩石孔喉结构分析

刘堂宴 ,王绍民 ,傅容珊 ,周明顺 ,李艳华 ,罗曼 .核磁共振谱的岩石孔喉结构分析 .石油地球物理勘探 ,2 0 0 3,38(3) :32 8～ 333岩心核磁共振 T2 谱和压汞分析数据均在一定程度上反映了岩石的孔喉结构 ,理论分析表明 ,这两组数据具有相关性。应用岩心核磁共振 T2 谱研究岩石孔喉结构 ,关键是确定 T2 与 Pc的转换系数。但以前的方法在 T2与 Pc 的转换过程中 ,需要涉及某些岩石特性参数 ,实用中有一定困难。本文直接利用岩心核磁共振 T2 谱和压汞分析数据之间的相关性 ,客观地确定 T2 与 Pc之间的转换系数 ,避免了确定岩石特性参数的困难。应用本文方法 ,对 6块岩心的多种核磁共振分析数据进行了对比分析 ,做出了 NMR (Nuclear Magnetic Resonance,简称NMR) T2 毛管力曲线和孔喉半径分布 ,并将这些结果与压汞分析的结果进行了对比。结果表明 ,岩心 NMR T2谱在实用性和评价精度上均略显优势 ;至少是在饱含油的条件下 ,岩心的 NMR T2 谱可以用于研究孔喉结构分布 ,油气的弛豫特性作为影响背景值存在 ,对于评价结果没有明显的影响 ;在全部 6块岩心中 ,T2 与 Pc 的转换系数位于 2 5 0 0～ 4 0 0 0μs· MPa之间。     

影响铁精矿K2O、Na2O、SiO2含量的因素分析

用统计分析方法 ,分析了影响精矿K2 O、Na2 O、SiO2 含量的因素 ,并根据分析结论提出了对生产工艺进行定向控制的条件     

机械合金化过程中Fe70B30粉末晶粒尺寸和微观应变的研究

用Ｘ射线和电镜研究了Ｆｅ＿（７０）Ｂ＿（３０）粉末经不同时间高能球磨后晶粒尺寸和微观应力的变化。在机械合金化过程中，粉末的Ｘ射线衍射谱的宽度随球磨时间的增加逐渐加宽，这是晶粒细化和内部微观应力共同作用的结果。Ｘ射线衍射结果表明：随着机械合金化的进行，粉末的晶粒尺寸逐渐减小，球磨初期晶粒尺寸下降较快，经１５ｈ球磨，晶粒尺寸为２５ｎｍ，机械合金化进行到一定时间后晶粒尺寸下降缓慢，８０ｈ球磨后晶粒尺寸可达５ｎｍ。在机械合金化过程中球磨所造成的微观应变不大，球磨初期粉末的内应力随球磨时间增加而增加，当粉末粒子尺寸很小时，随球磨的进行粉末中的微观应变显著下降。     

Electrical/electronic effects of titanium and iron impurities in EFG and FZ solar cell silicon: SPV/EBIC analysis

In this paper results on surface photovoltage (SPV) and electron beam induced conductivity (EBIC) studies of edge-defined film-fed growth (EFG) and floating zone (FZ) silicon solar cell materials (both p-type) are presented. A systematic comparison based on minority carrier diffusion length and carrier recombination is made between: (i) samples contaminated with Ti and/or Fe, (ii) samples gettered by phosphorous diffusion, and (iii) as-received samples. Deep level transient spectroscopy (DLTS) measurements, together with the iron-boron (FeB) pairing kinetics [1] have successfully been used to detect the presence of Fe in the samples. Even though this process is effective in revealing Fe impurities in p-type FZ silicon it is evidently not suitable for Fe identification in p-type EFG silicon. Ti, like Fe, is found to be a prominent lifetime-limiting metallic impurity in both EFG and FZ silicon. Phosphorous diffusion is proven to be an effective external gettering technique for fast-diffusing impurities such as Fe, but not for Ti.     

胜利油区放射性同位素测井的粒径选择

根据胜利油区的地层渗透率、孔隙度，在２７个低渗透油田和４６个中、高渗透油田的放射性同位素测井中进行了粒径为１００～３００μｍ、３００～６００μｍ、６００～９００μｍ放射性同位素１３１Ｂａ微球粒径选择实验，确定了放射性同位素１３１Ｂａ微球的选择原则。当油藏渗透率Ｋ＜１００×１０－３μｍ２、孔隙度＜２０％时，放射性同位素粒径为１００～３００μｍ；当油藏渗透率Ｋ＞１００×１０－３μｍ２、孔隙度＞２０％时，放射性同位素粒径为３００～６００μｍ或６００～９００μｍ。在此基础上得到胜利油区选用同位素粒径明细表，对于指导施工，提高放射性测井资料的可靠性具有重要意义。     

On the applied stress dependence of the subgrain size

The present work studies the collection of experimental data from which Raj and Pharr (Mater. Sci. Eng., 81 (1986) 217) deduced a universal empirical dependence of the subgrain size on the applied stress. In accord with their result and some theoretical predictions the normalized subgrain size d_s/b was ssumed to be proportional to G/σ (G is the shear modulus, b the Burgers vector length, σ the applied stress). The evaluated factor of proportionality K₁, having the value within the interval from 0.76 to 180 in the inspected data sets, was discussed from the point of view of various factors which can influence the experimental data.     

Prediction of High-Temperature Long-Term Strength for Damaged Structures

A method is proposed for analytical estimation of the high-temperature long-term strength of structures with material discontinuities, which are stress raisers. We consider the processes involving the formation of diffusion pores. Diffusion processes in metals are strongly enhanced with increasing temperature and stresses.     

鼓风引射式燃气燃烧器的计算

提出鼓风式射式燃气燃烧器的基本计算公式与计算结果，并进行结构尺寸与工况分析，确定各种因素对其的影响程度。