模拟光纤数据传输系统的研究

讨论了脉冲频率调制（ＰＦＭ）光纤传输系统的特点，分析了半导体发光器件和检测器件对模拟光纤传输系统的影响．研制了实用的工业光纤传输系统，并给出了系统的测试结果及性能．     

Durability of asphalt mixture in different corrosion solution

The corrosion to asphalt mixture under different kinds of corrosion solution, such as pH=2 solution, pH=12 solution, pH = 12 solution and 10% Na₂SO₄ solution, was studied. The performance attenuation of asphalt mixture was analyzed under the normal environment and the freeze-thaw environment, and the analysis was given on the sensitivity of the test results to the evaluation index. The experimental results show that the performance of asphalt mixture is attenuated faster under the acidic solution, alkaline solution and sulfate solution. Corrosion factor K _c, freeze-thaw corrosion factor K _f, and freeze-thaw effect factor K _fc are proposed to evaluate asphalt mixture resistance to corrosion in different kinds of corrosion solution. The values of K _c and K _fc decrease with the increasing of corrosion time. The change rule of K _f show that the rate of corrosion is decreased by the action of freeze-thaw in acidic solution and in alkaline solution, but is increased by the action of freeze-thaw in sulfate solution. The microscopic analysis indicates that acid solution reacts with aggregate of asphalt mixture, alkaline solution reacts with asphalt cement of asphalt mixture, the surface tension of sulfate solution and crystallization of sulfate are the main reasons which weak the performance of asphalt mixture.     

世界航空钛市场现状及发展趋势

介绍了美国、俄罗斯、欧洲及亚洲的航空钛市场现状,分析了民用客机、军用飞机及航空发动机对钛材的需求形势。目前,世界航空钛市场处于复苏阶段,波音与空客两大公司的订单开始大幅增加。世界航空钛市场中长期前景看好,用钛量将持续攀升。预计到2015年,世界航空用钛材交货量将达到12.5万t。     

高碳铬铁降碳探讨

介绍了在12 5MVA电炉上进行高碳铬铁降碳的试验情况 ,分析了影响FeCr67C6 0合金含碳量的因素 ,从理论和实践两方面阐述了降碳措施     

Purification and characterization of maize starch synthase I and its truncated forms

A number of imidazole-based compounds were tested for their utility as (1)H NMR molecular probes of intracellular pH. Imidazole, previously found useful as a probe of erythrocyte pH, reported a pH in perfused canine glioma cells that was more than 1 pH unit lower than that reported by inorganic phosphate, consistent with the known lysosomal compartmentation of the molecule. Imidazole acetate, also proposed as an NMR probe of cellular pH, was found not to enter the cells of this study. Histidine was found to be readily taken up by cells and reported a pH consistent with that reported by inorganic phosphate. Using the chemical shift of the histidine H2 proton in cells incubated with 10 mM histidine, cellular pH measurements could be obtained in less than 1 s. This compares quite favorably with the measurement time, typically several minutes, needed to assess in vivo pH by (31)P NMR. The use of histidine as a probe of pH is demonstrated in perfused canine and rat glioma cells subjected to ischemia or to low extracellular pH.     

蜂毒溶血肽(Melittin) cDNA的克隆及序列分析

为了克隆得到正确序列的蜂毒溶血肽cDNA，对蜂毒中的蜂毒溶血肽进行了研究。实验从蜜蜂毒腺中提取总RNA，通过RT－PCR方法扩增到了蜂毒溶血肽的cDNA，扩增产物克隆到pT7Blu-T载体，转化大肠杆菌JM109，DNA序列分析结果表明克隆得到的蜂毒溶血肽cDNA脱氧核糖核苷酸序列正确。     

连续五年保持高产的低渗透油藏实例研究

针对怀俄明西南Wamsutter油田的阿尔蒙特和路易斯低渗透砂岩油藏, 组织了一支科研小组.该小组于1998年对油藏进行研究,以解决生产井产量低的问题.研究小组面临的挑战包括:①确定生产井是否已达到最高产量;②确定一个基准值,以衡量各种改进措施是否成功;③找出低产的主要原因;④应用新技术和新工艺解决低产问题;⑤采取增产措施,提高生产井的净现值;⑥将完井过程中各种措施的效果记录下来.开始时,将90天的平均产量作为基准值,结果5年内超过基准值100%,生产井的平均产量也提高了50%以上.     

高pH法处理循环冷却水

采用静态阻垢、旋转挂片腐蚀、电化学和微生物培养等方法研究了高pH水的水质特性,结果表明:碳钢在高pH水中的腐蚀速率较低,在9≤pH≤11范围内,腐蚀速率随pH的升高而下降,当pH升高到11～13时,腐蚀速率随pH的升高而略有升高;碳酸钙垢析出速度和晶型也随pH的变化而改变,当pH≤12时,析出的碳酸钙为六方碳钙石和方解石形态的晶型,当pH=13时,析出的碳酸钙晶体主要为不定形碳酸钙;而且高pH会影响异养菌和硫酸盐还原菌的活性,pH越高异养菌和硫酸盐还原菌的死亡率越高.     

Mechanism and Inhibition of Grain Coarsening of Al-Mg-Si Alloy in Hot Forming

A high-Ti 6061 alloy was rolled with strains up to 0.8-2.0 and at 350-550 ℃. Microstructures that developed during deformation and subsequent solution heat treatment (SHT) were observed by using optical and transmission electron microscopy. Microstructure evolution during SHT depends mainly on the initial rolling temperature, and it was found that the higher this temperature is, the coarser the grains are. After rolling at 400 ℃, well-defined cells and subgrains were formed, which induced further sites for recrystallization nucleation during subsequent SHT. The recrystallization mechanism was found to be subgrain rotation, with a final grain size smaller than 200 μm. Increasing the rolling temperature to 500 ℃ results in a low density of dislocations distributed uniformly in the deformed matrix and fewer nucleation sites during subsequent SHT. The recrystallization mechanism is grain boundary bulging, while the final grain size approaches several millimeters. Finally, a hot forming process of high-Ti 6061 alloy for inhibiting grain coarsening was proposed, and verified by experiments.     

侧向土体影响下盾构隧道引起上覆管线变形

目前盾构隧道开挖对邻近管线影响的理论研究一般基于Winkler地基模型和Pasternak地基模型,较少考虑精度更高的Kerr地基模型及管线侧向土体影响对管线变形的约束作用. 将管线简化成Euler-Bernoulli梁搁置在Kerr地基模型上,利用差分法得到盾构隧道引起上覆管线竖向位移半解析解,在此基础上进一步推导考虑管线侧向土体影响的Kerr地基模型差分解. 通过与已有工程案例和离心机数据对比,验证Kerr地基模型相比于其他地基模型的优越性,也验证了考虑管线侧向土体影响的Kerr地基模型计算结果更加符合实测数据. 参数分析表明, 随着隧道开挖地层损失率和土体弹性模量的增大,管线的竖向位移和弯矩均增大;随着管线与隧道夹角的增大,管线的竖向位移和弯矩均减小.