Formation Mechanism of MoO3-Doped YSr2Cu3Oy Using the Citrate Process

The formation mechanism of the synthesis of MoO₃-doped YSr₂Cu₃O _y powders using the citrate process was investigated. It was shown that the precursor phase (Sr_{1- x} Y _x )₁₄Cu₂₄O₄₁ played a crucial role in forming the superconducting phase. It was found that the precursor phase (Sr_{1- x} Y _x )₁₄Cu₂₄O₄₁ interacted with water and decomposed when it was heavily milled and heated.     

激光扫描共焦荧光显微镜的电子控制系统研究

介绍了激光扫描共焦荧光显微镜的电子控制系统，为了提高激光扫描器的定位精度，在系统中提出采用基于闭环象素时钟发生器的检流计振镜所固有的扫描非线性失真补偿方案，减少输出图象的枕形畸变，实现行扫描空间位置的均匀性。在以细分梯形波电流驱动反应式步进电机情况下，根据实测θｉ曲线，用反插法求得与步进电机运行非均匀性相补偿的相电流波，从而获得在小电流情况下高角度均匀的步进电机细分运行特性。     

Why spin = 1, 2 species have no electron paramagnetic resonance signal under normal conditions: possible detection by electron paramagnetic resonance at frequency close to D value?

A universal EPR simulation program has been created by the author, which is based on the following spin Hamiltonian equation: [equation: see text] where D and E are the axial and rhombic zero-field splitting parameters, respectively. The program can be used for simulation of EPR spectra with half-integer electronic spin (S = n/2, n = 3, 5, 7, 9) systems. In this article, the integer spin (S = n/2, n = 2, 4) systems are also considered. The EPR simulation results show that when D > frequency, no EPR signal can be seen from EPR simulation; when D approximately frequency, whichever X/Q/W-band is used, the EPR signal can be seen on the basis of the simulated EPR results presented.     

Sliding wear of Al2O3P/6061 Al composite

The mild sliding wear behaviour of a 15 vol % Al₂O_3P/6061 Al composite has been investigated by using a pin-on-disc reciprocating sliding machine. The composite has been shown to exhibit an excellent wear resistance as compared to the unreinforced matrix alloy. The wear rate of the composite under dry wear conditions with a 12N load is approximately one tenth of that in the 6061 aluminium alloy. The wear rate of the composite under lubrication with 15W/40 gear oil under a 100N load is only one thousandth ofthat in the 6061 aluminium alloy.The dry wear resistance of an over-aged sample is shown here to be better than a peak aged or under-aged sample when the composite was aged at 160°C. The coefficient of friction of the composite was approximately 0.5–0.6 under dry conditions and 0.07 in lubricated wear experiments.In the initial stage, the worn surface of the composite under dry conditions is primarily composed of ploughed grooves and ductile tear. The composite makes a conducting contact with the steel pin. The worn surface is composed of compacted powder and the contact potential gradually increases when the period of the wear experiment goes beyond 2 h.     

金属蒸气法制备聚合物固载Pd－Cu双金属原子簇

为了不使用任何还原剂而获得聚合物固载高分散零价双金属加氢催化剂，利用金属蒸气法制备了３种不同Ｐｄ／Ｃｕ质量比的聚合物固载双金属原子簇。透射电镜（ＴＥＭ）和Ｘ衍射（ＸＲＤ）测定表明，Ｐｄ－Ｃｕ原子簇粒度很小，平均直径小于３．０ｎｍ。Ｘ射线光电子能谱（ＸＰＳ）表明，Ｐｄ和Ｃｕ均为零价态。Ｐｄ－Ｃｕ原子簇在异丙叉加氢反应中具有很高的活性和选择性。这些结果提供了令人信服的证据，即金属蒸气法可用于在聚合物孔穴内直接而温和地置入小的零价金属原子簇，而且这样制备的聚合物固载金属原子簇很适合于催化应用。     

On the J-integral in periodically layered composites

When a heterogeneous elastic material is represented by an effective homogeneous elastic solid, average stress and strain fields are used. The meaning of the J-integral in the effective homogeneous solid is investigated. A periodically layered medium is considered. The relation between the J-integrals in the original layered medium and the effective medium is derived.     

An anthropocentric approach to knowledge-based preventive maintenance

It is common knowledge today that application of sound manufacturing concepts and techniques will only provide cost-effective, long-term return when manufacturing functions are totally integrated with the operators, maintenance engineers and other associated personnel. This paper presents a human-centred methodology and its associated knowledge-based tool, to utilize equipment failure information for the purpose of machine down-time minimization. Based upon a structured and rigorous assessment of each breakdown, and combined with total employee participation, continuous improvement of maintenance function and operational effectiveness of equipment can be made a reality.