铜铟铋硫对Sn-Ag基无铅焊料性能的影响

研究了Cu、In、Bi、S元素对Sn-Ag基无铅焊料熔点和铺展性的影响。结果表明:Sn-Ag-Cu三元合金成分为95.5%Sn3.5%Ag1%Cu时具有较低熔点(215℃)和好的铺展性;加入适量的In可降低Sn-Ag合金的熔点和改善铺展性能;随w(Bi)的增加Sn-Ag-Bi三元合金的熔点降低、铺展性变好;Sn-Ag合金的熔点随w(S)的增加而升高,加入少量S能改善Sn-Ag合金的铺展性。     

工业层析洗梯液回收套用的一种方法

以生产甲胺基阿维菌素苯甲酸盐精品的工艺——工业层析产生的洗梯液回收套用的过程为例，说明利用二元恒沸物的组成随压力的变化而变化的规律，对生产洗梯液进行有效、简洁、合理分离及套用的方法。     

Preparation and properties of silicone‐containing poly(methyl methacrylate) gels

Poly(methyl methacrylate) (PMMA) gels with varying amounts of silicone and solvent and constant amounts of crosslinker were prepared by solution free radical crosslinking copolymerization of methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) comonomer systems. They were then studied in benzene at a total monomer concentration of 3.5 mol L^?1 and 70 °C. The conversion of monomer, volume swelling ratio, weight fraction and gel point were measured as a function of the reaction time, silicone concentration and benzene content up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in benzene, gel fraction and Fourier‐transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by SEM. Based on the obtained results, it was concluded that the FTIR data did not have the capacity to show the presence of the VTES or TEOS moiety in these kinds of copolymers. On the other hand, the variation of weight fraction of gel, W_g, and its equilibrium volume swelling ratio in benzene, q_v, exhibited the same behaviour as that of MMA/EGDM copolymers. Also, the dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percent of conversion and gel fraction. Finally, TEOS is not an ideal silicone compound for reaction in the MMA/EGDM copolymerization system, whereas VTES is a suitable silicone comonomer for this system and it has been proved useful. Copyright © 2005 Society of Chemical Industry     

VARIATIONS IN ALFALFA JUICE SOLUTE CONCENTRATIONS AS WATER IS EVAPORATED

Alfalfa juice was extracted from plants during the graving phases of the first and second crops. The alfalfa juice was dried and solute concentrations were measured periodically during the process using freezing point depression (FPD) as an indicator. Solute/solvent weight ratios were calculated from the freezing point depression of fresh unconcentrated 'uice extracted from both firsc and second crops. At the time of harvest, tie FPD was a function of this ratio. The first and second crops behaved distinctively different during the drying process, with the second having a larger soluce concentration and a greater FPD at a given moisture content. The appearance of preci itate during the drying process and the general1 large FPD makes this materiay a questionable product for drying vitg low temperature processes.     

Fixed point theorems on fuzzy normed linear spaces

In this paper, definitions of strongly fuzzy convergent sequence, l-fuzzy weakly convergent sequence and l-fuzzy weakly compact set are given in a fuzzy normed linear space. The concepts of fuzzy normal structure, fuzzy non-expansive mapping, uniformly convex fuzzy normed linear space are introduced and fixed point theorems for fuzzy non-expansive mappings are proved.     

二阶曲线渐近线的等价定义及其应用

给出了射影几何中关于二阶曲线渐近线的几个等价定义,并探讨了根据不同 定义的二阶曲线渐近线的应用．     

点检定修在实际应用中的初步探讨

介绍点检定修在发电厂中的应用，根据十里泉发电厂设备维修的经验提出点检定修向状态检修过渡的方法。     

A new method for the determination of wax precipitation from non-diluted crude oils by fractional precipitation

Wax precipitation is one of the most important flow assurance problems. Unfortunately, experimental data are very scarce to confirm existing models for prediction of such precipitation problem. This work reports a new experimental method. Multistage fractional wax precipitation was carried out by decreasing the temperature of crude oil. No solvent dilution was used, so the effect of solvent on temperature wax precipitation was avoided. The reproducibility of the method was tested with comparable results. The precipitation curve and the wax appearance temperature were obtained for two crude oils with different chemical nature using the reported method.     

锅炉未焊透椭圆接管结构应力数值分析

应用有限元法对未焊透的椭圆接管结构进行了应力数值分析,并应用压力容器分析设计法,对该结构进行了疲劳分析,得出结构因未焊透缺陷导致疲劳破坏。     

凸轮逆序测量方法

目前各杂志所发表的关于凸轮测量的文章，所讨论的均是凸轮的顺序测量方法，有关凸轮的逆序测量(反求工程)方法，尚未见于文字。本文将对凸轮的逆序测量方法进行探讨。