北太平洋500hpa候高度场的主成分分析

对太平洋500hPa候高度场和距平场进行了主成分分析,得出反映500hPa候高度特征的典型场。指出候高度场的第1特征向量的空间型是季节变化的主要型,它可解释总方差的74.5％,候高度场的其余特征向量与距平场的特征向量是按顺序的对应相似。这些典型场可以很好地描述北太平洋的大气环流特征。距平场的第1特征向量空间型清楚地反映了与厄尔·尼诺现象有关的环流型。     

Calculation of the Intensity Ratio and Intrinsic Redshift Ratio of the Cerenkov Iron Kα and Kβ Lines and Its Possible Application in the Study of AGNs

We have pointed out that, when thermal relativistic electrons with an isotropic velocity distribution move through a region of dense gas or impinge upon its surface, the Cerenkov effect will produce a particular kind of atomic or ionic emission line, which we have called the “Cerenkov line-like radiation”. This prediction for the optical wavebands has been verified by laboratory experiments. In this paper, we extend this line-like radiation theory to the X-ray waveband and give the basic formulae for calculating the intensity ratio and intrinsic redshift ratio of the Cerenkov iron K_α and K_β lines, for different ionization orders of iron. Potential application of this calculated result may be found in the study of AGNs. The recent observations of NGC3783 show that besides the iron K_α line at ∼6.4 keV, there is also a very strong iron Kβ line at ∼7.0 keV, and that the ratio of equivalent widths between the two is anomalous: EWK_α/EWK_β ≈ 3.43. It is difficult to explain this by the conventional mechanism of “photoelectric absorption-fluorescence emission”. We suggest that the mechanism of Cerenkov line-like radiation can provides a way of solving this puzzle. Besides, we expect that the calculated intrinsic redshift ratio of Cerenkov iron K_α and K_β lines could be tested in future observations. If our suggestion is further supported by observations, then our view on the physical environment around the central massive black hole of an AGN will be greatly modified: the activity becomes more energetic and violent, and the gas, much denser than previously thought.     

Noah-MP模型中积雪模拟对参数化方案的敏感性评估

针对Noah-MP模型多参数化方案、模拟结果不确定性范围难以确定的特点,选取北疆地区具有代表性的阿勒泰站气象资料作为模型驱动数据,探讨了积雪对多参数化方案的敏感性。在不考虑模型参数和驱动数据不确定性的条件下,设计了集合数为13824的多参数化方案集合模拟试验。选用Natural selection方法对物理过程的敏感性进行分析,并在敏感性分析结果的基础上进一步讨论了模拟结果的不确定性。结果表明:积雪对地表热交换、雨雪分离、土壤温度底层边界条件和第一层积雪或土壤时间方案4个物理过程敏感;在不考虑驱动数据和模型参数不确定性的条件下,多参数化方案集合模拟试验中的不确定性主要来源于敏感物理过程。去除敏感物理过程中能够明显降低模拟性能的参数化方案后,集合模拟结果的不确定性大幅减小。最后,根据分析结果构建了该站雪深和雪水当量模拟的最优参数化方案组合。     

Hydromechanical behavior of unsaturated soil with different initial densities over a wide suction range

Acta Geotechnica - Many civil engineering projects are related to hydromechanical behavior of unsaturated soils over a wide suction range, which was investigated by imposing suctions on clayey silt...     

地方政府竞争对城市土地利用效率影响分析

利用面板随机前沿分析法研究了2009-2015年期间地方政府竞争对中国城市土地利用效率的影响,为规范地方政府的竞争行为并提高中国城市土地利用效率提供政策参考.研究结果表明:地方政府基础设施竞争对中国城市土地技术效率的提高具有促进作用,但效果并不显著,而地方政府财政收支竞争、土地优惠政策竞争及外商直接投资竞争都不利于城市土地利用效率的提高.进一步测算各地区土地利用的技术效率发现,地方政府竞争影响下中国东、中、西部城市土地利用个体技术效率均出现明显下降.因此,应进一步完善城市土地利用中的地方政府竞争关系,改革地方政府官员考核机制,为城市土地集约利用提供良好政策环境.     

Morphological and phylogenetic analysis of a new Melosira species and revision of freshwater Melosira in China

Journal of Oceanology and Limnology - Melosira is one of the most common diatom genera found in freshwater ecosystems. There are many freshwater species of Melosira, of which M. varians is the most...     

HaleBopp彗星的爆发活动

９９６ 年９ 月至１１ 月间,对ＨａｌｅＢｏｐｐ 彗星进行了照相和光电观测．给出观测结果,包括几次爆发和可能的爆发活动     

材料强度理论新探

本文依据弹塑性变形相关关系,对材料的强度理论进行探讨,提出了一种新的强度理论,该理论和试验结果吻合良好。     

螺旋藻多糖对CD3AK细胞增殖能力的影响

研究了螺旋藻多糖（ＰＳ）对ＣＤ３ＭｃＡｂ激活的杀伤细胞（ＣＤ３ＭｃＡｂ Ａｃｔｉｖａｔｅｄ Ｋｉｌｌｅｒ Ｃｅｌｌｓ,ＣＤ３ＡＫ Ｃｅｌｌｓ）增殖能力的影响。结果表明,当ＰＳ浓度为２．５μｇ·ｍｌ＾－１培养体系条件下,对ＣＤ３ＡＫ细胞具有明显的刺激细胞增殖作用（Ｐ〈０．０２）;对培养长达２３ｄ的ＣＤ３ＡＫ细胞杀伤肿瘤细胞（Ｋ５６２细胞）的活性仍维持在较高的水平（４６．５％￣５０％）。提示ＰＳ对辐射