脉冲激光轰击法连续制备纳米金掺杂YBCO

利用超声法获得钇钡铜氧（YBCO）和乙醇混合溶液,采用聚焦脉冲激光轰击浸于流动无水乙醇中的金靶,连续制备得到纳米金和乙醇混合溶胶.将纳米金和乙醇混合溶胶直接滴入接收器中的YBCO和乙醇混合溶液中,经干燥获得纳米金掺杂的YBCO材料.结果发现,纳米金未明显改变YBCO的吸放热现象,对样品的组成影响不大;掺杂0.01%、0.05%重量比例的纳米金后YBCO的结晶度和超导转变温度Tc均有所提高.     

Evidence of diadromy in the French Polynesian Kuhlia malo (Teleostei: Percoidei) inferred from otolith microchemistry analysis

Abstract – Strontium/Calcium (Sr/Ca) and Barium/Calcium (Ba/Ca) ratios were measured in 60 otoliths of the French Polynesian flagtail Kuhlia malo. Both elemental ratios were needed to correctly distinguish residence in marine, brackish and fresh water. High Sr/Ca and low Ba/Ca around the nucleus of all otoliths provided evidence of marine residency during the early life of all individuals. At about 0.5 mm from the core, Ba/Ca increased rapidly and remained high in all otoliths. High and unstable Sr/Ca ratios were attributed to estuarine residency, whereas low and stable Sr/Ca ratios were attributed to freshwater residency. These chemical signatures inferred that following recruitment to rivers, some fish remained in the estuary, while others moved upstream. Some individuals shared their time between fresh and brackish waters later in life. The findings of this study have important implications for the protection of nearshore, brackish and freshwater environments for the conservation of this French Polynesian diadromous species.     

中原牡丹花黄酮定量方法的研究

借助于紫外扫描,通过对氯化铝显色法、硝酸铝—亚硝酸钠显色法和直接测定法3种比色方法与高效液相色谱法测定结果的对比和方法评价的研究,确定了直接测定法(测定波长为350 nm)是一种操作简单、结果较准确的方法。以芦丁为标准品,可用于中原牡丹花黄酮含量的快速测定。     

飞秒激光微加工中热熔化与热传递现象研究

对飞秒激光能量密度为0.108~28.68J/cm2范围内加工的硅孔表面形貌尺寸进行分析,同时对热传递现象进行研究。理论分析了飞秒激光加工区域热传导时间及温度分布,并将其与实验测量值进行对比,验证了热影响的存在。通过理论与实验分析说明了在高能量飞秒激光加工中热传递现象不可避免,并获得了较好的孔加工质量的激光能量合理参数。     

板料激光斜冲击下受力变形数学分析

金属板材的激光冲击成形通常采用激光束垂直作用于工件表面,产生垂直于表面的冲击波作用力使板料变形,但在曲面零件成形时很难满足法向垂直冲击,因此有必要对斜冲击下板料力学变形特性进行研究。本文研究了激光斜冲击受力变形模型,对板料深度方向(z轴)变形公式、板料短轴(y轴)在水平方向上变形公式进行了理论推导计算,通过把两变形合成,得到短轴(y轴)在空间内总变形公式,最后把实验测量结果与理论计算结果进行了比较,得出两者相符的结论。     

35CrMo旋转接头激光表面硬化技术的试验研究

用L9(34)正交试验法研究35CrMo旋转接头激光相变硬化工艺参数优化组合,分析了旋转接头激光相变硬化方法.试验结果表明:激光相变硬化层硬度比渗氮淬火提高了30%,耐磨性提高了1倍,表面残余应力为压应力;满足了旋转接头工作要求,为改进旋转接头表面处理方法提供了依据.     

板材三维曲面的无模多点闭环成形技术

基于具有并行调形功能的多点快速曲面造型系统和自主开发的激光扫描测量机，提出了三维板类件多点闭环精确造型的概念，并应用PID控制算法进行了多点闭环成形实验，得到了符合设计要求的工件形状。讨论了三维板类件多点成形逆向工程的实现问题。     

利用CT扫描技术确定土壤大孔隙分形维数

土壤大孔隙的大小、形状和分布对水及溶质在土壤中的运移有着深刻影响,由于土壤大孔隙的分布呈现分形规律,根据采用CT扫描法得到的原状土柱各断面图像,采用计盒维数法计算出各断面土壤大孔隙的分形维数。     

北京地区乔木郁闭度测量研究

比较了国内外已有的乔木郁闭度测量方法的优缺点,在样点法特别是观测管法的基础上,以北京延庆地区乔木林为对象,对郁闭度的激光测量进行了研究。实验改进了观察管法,对在野外测量乔木林郁闭度时精确测量所需样点数进行了研究,可以为野外快速、简洁、精确地测量乔木林郁闭度提供新的方法与参考。     

Color Image Compression Method Based on Incomplete Scanning Method

In view of color image characteristic, the paper improves the zero algorithm in the application of concrete algorithm, draws a new algorithm-incomplete scanning method, which is applied to color image compression. The authorsconvert color image from the RGB space into luminance-chrominance YUV space, then compress the converted image to encode/decode. Theoretical analysis and simulation experiment indicate that the compression ratio and encoding/decoding speed are increased, at the sase time the quality of restored image is guaranteed.