日本落叶松人工林生物量及生产力的研究

在长岭岗国营林场调查了日本落叶松人工林林分24块标准地，并测定了单株平均木的各器官生物量，结果表明：应用W=a（D^2H）^b模型来估测日本落叶松人工林生物量，其相关程度达显著水平；日本落叶松人工林单株林木各器官的生物量随年龄变化符合理查德（Richards）生长方程；日本落叶松人工林单株林木生物量年平均生长量在26a时达到顶峰；日本落叶松人工林林分生物量24a时达293．40t／hm^2，生产力为20．78t/（hm^2．a）．     

Reduction of the East Asian winter monsoon interannual variability after the mid-1980s and possible cause

The East Asian winter monsoon (EAWM) consists of subsystems such as the Siberian high, Aleutian low, East Asian trough, low-level northerly wind and high-level East Asian jet stream. It is revealed that the interannual variation of the EAWM-related atmospheric circulation has exhibited an obvious weakening since the mid-1980s. During 1956-1980, significant negative correlations between the EAWM and sea surface temperature are observed in the oceans along the east coast of East Asia, accompanied by significant positive correlations in the western Warm Pool. However, the significant interannual relationship in the previous period is found to have been disrupted during 1986-2010. Further analysis reveals that the Arctic Oscillation after the mid-1980s tends to suppress the interannual variability of the EAWM. In addition, it was found that the large-scale warming after the mid-1980s is favorable to reduce the land-sea thermal contrast variability on both the interdecadal and interannual time scales.     

有限推力模型火星探测捕获策略分析

本文提出了基于有限推力模型,目标约束为轨道半长轴和偏心率的火星探测器的捕获问题.分析了三种捕获方式：燃料最优捕获、姿态匀速转动和姿态惯性定向捕获策略,并分别利用最优控制和粒子群优化算法针对不同捕获策略进行了求解.分析表明,以燃料最优为指标的捕获策略为邦邦控制,其推力方向基本沿着与飞行速度相反的方向,但在工程实现中对姿态控制系统要求很高,难以实现.捕获过程中姿态惯性定向易于实现,但是重力损失比较严重.姿态匀速转动的捕获策略比邦邦控制更容易实施,并且能有效地减小重力损失,因此在工程中有很重要的实用价值.     

The increase of snowfall in Northeast China after the mid-1980s

We studied long-term variation of winter snowfall in Northeast China (NEC) for 1951-2010. Results show that NEC snowfall increased about 20% during 1986-2010 relative to 1951-1985. Further investigation suggests that the snowfall increase is closely associated with weakening of the East Asian winter monsoon (EAWM). The physical processes were portrayed by this research. Weakening of EAWM led to weakened cold air flow from the north, thus resulted in the warming of the surface ocean along the Northeast Asia coast and more water vapor evaporated from the ocean surface to the atmosphere and further transported to NEC. Also, because of EAWM weakening, more water vapor from south, east and west of NEC was transported to NEC, increasing water vapor content and hence snowfall there. From an atmospheric circulation viewpoint, EAWM weakening strengthened convergence at low levels and divergence at high levels, thereby favoring increased vertical convection and snowfall.     

负载型TiO2催化剂的制备及其酯交换反应性能

采用水解法制备负载型TiO2／SiO2催化剂,用于苯酚和草酸二甲酯酯交换反应．通过考察催化剂焙烧温 度、载体粒径、催化剂用量、活性组分负载量和反应时间等因素对该酯交换反应的影响,确定出较佳的催化剂制备 工艺及反应条件．负载型氧化钛催化剂在该酯交换反应中表现出活性好、选择性高、催化剂易分离回收等优点．以 550℃焙烧的TiO2／SiO2为酯交换催化剂,TiO2负载量为13％,反应时间2h,反应温度180℃,草酸二甲酯的转化 率、甲基苯基草酸酯和草酸二苯酯的选择性分别为53．1％、72．1％和27．3％．     

金属材料的超声衰减特征及辨识的新方法

利用超声技术研究了辨识金属材料的方法.以成分相近、热处理温度相同和成分相同但热处理温度不同的多个金属材料为例,计算了金属材料对不同频率超声波的衰减系数,分析了同一频率下采样率对超声衰减谱稳定性的影响,研究了金属材料的微观组织对超声衰减的影响.结果表明,采样率越高,衰减谱的多次实验计算越趋于稳定;金属材料的超声衰减谱与其微观组织结构密切相关,其携带有金属材料的微观组织特征信息;利用金属间超声衰减谱相关系数可辨识金属材料,对贵重金属、金属文物等的防伪与辨识提供了一定的参考依据.     

Weakening relationship between East Asian winter monsoon and ENSO after mid-1970s

The East Asian winter monsoon(EAWM) is characterized by the frequent cold surges and associated closely with the Siberia High,East Asian Trough,and high-level westerly jet stream.The ENSO cycle can modulate the EAWM since it has co-variability with the sea surface temperature over the Indo-Western-Pacific which can tune the land-sea thermal contrast for the EAWM.This paper,by analyzing the EAWM,ENSO,and associated atmosphere-ocean variability,documents the weakening of the EAWMENSO relationship after the 1970s.The significant out-of-phase inter-relationship is found to be diminished after the 1970s.Further study in this work suggests that the weakened co-variability of the tropical Indo-Western-Pacific climate associated with ENSO after the 1970s is partly responsible for the weakened inter-relationship.Meanwhile,the reduced EAWM interannual variability and northward retreat of the EAWM-associated climate variability are favorable to the weakened ENSO-EAWM connection.     

Yb(OTF)3催化2,4-二氨基甲苯与碳酸二甲酯甲氧羰基化合成2,4-甲苯二氨基甲酸甲酯

研究了Yb（OTF），催化剂对2，4-二氨基甲苯（TDA）与碳酸二甲酯甲氧羰基化反应合成2，4-甲苯二氨基甲酸甲酯（TDC）的催化活性，考察了反应温度和反应时间对Yb（OTF），催化活性的影响。在该催化剂的作用下，反应温度453K，反应时间5h时TDA转化率可达100％，TDC的产率达到23、6％，同时考察了Yb（OTF）3催化剂的寿命，经4次重复使用催化剂基本不失活。Ln（OTF）3（Ln=La，Nd，Yb）催化活性的比较表明催化剂Lewis酸性的强弱与TDC的产率成正比。