利用JCZ-1T地震计BB通道观测数据检测地球自由振荡

采用库尔勒台JCZ-1T地震计BB通道垂直向的观测数据,利用功率谱密度估计方法,在没有对观测资料进行任何改正的情况下,获取2016-03-02印尼苏门答腊岛海域7.8级和2016-04-17厄瓜多尔7.5级大地震激发的0S7～0S60基频球型自由振荡,并与PREM模型理论值进行对比分析。结果表明,实测值与理论值相吻合,除部分振型与理论值偏差较大以外,其余振型与理论值偏差均小于0.1％。印尼苏门答腊岛海域7.8级地震所检测的球型振荡能量频谱分布及振型与厄瓜多尔7.5级地震所检测的球型振荡有一定差别,前者所能检测的振型数量相对较多。     

Distribution of free electrons in the galactic plane

A method is proposed for constructing a map of the electron density distribution in the galactic plane. Data on the dispersion measures DM of more than 1500 pulsars and their distances, found by an independent method, are used. The independent distances of the pulsars are estimated using an empirical relation of the form L=γP ^α Ṗ ^β W ^δ between the radio luminosity L of the pulsars and their periods P, the rate of change Ṗ. of their periods, and the half width W of their pulses. A map of the electron density distribution in the galactic plane within a ±400 pc layer is provided. __________ Translated from Astrofizika, Vol. 49, No. 2, pp. 277–287 (May 2006).     

金州短水准观测和资料分析中的若干重要问题

对金州短水准观测和资料分析中常易引起争议或新出现的若干重要问题进行论论，其结果对跨断层形变测量具有普遍意义。     

自由测站法曲线座标计算程序设计

通过对曲线测设和测点坐标计算过程的分析，把坐标计算的程序设计归结为有向直线与X轴顺时针夹角即方位角的计算和线路转向转角的计算，弥补了测点位置和计算公式分类复杂等不足，简化了程序设计和计算过程。     

潜水面变动的空间四面体单元网格自动生成方法

提出了一种由平面三角网格自动生成三维空间四面体单元网格的方法,其基本思路是将含水层平面分成三角形单元网格,将每个三角形沿垂直方向对应一个三棱柱,作为最初的三棱柱;依次将每个三棱柱按照潜水面位置和分层信息划分成不同数目的四面体,从而生成三维空间四面体单元网格。剖分结果表明,此方法综合考虑了潜水面的位置和各含水层顶底板的起伏情况,能够简洁地生成层面起伏的空间四面体网格,特别适用于刻画潜水面波动、含水层顶底板起伏和存在透镜体或岩性缺失等含水层结构复杂的情况下,自动地剖分并生成单元信息,为三维计算的实现奠定了基础。     

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A poincaré model for the earth's fluid core

Abstract

The superconducting-gravimeter data of Melchior and Ducarme (1986) has been interpreted as internal motion in the Earth's core by Aldridge and Lumb (1987) using a Poincaré model. Several low-order modes with periods of 13–16 hours have been tentatively identified in the core which is taken to be an incompressible, homogeneous fluid within a rigid, rotating container. The identification is based on asymptotic values of the frequencies which change slowly with time while the modes decay with an e-folding time of about 280 days. The slow change in frequency with time implies a small temporal variation in the rotation rate of the core. This mean flow is a nonlinear effect often observed in laboratory experiments designed to excite Poincaré modes. Interaction among modes during free ringdown is also observed in those experiments and apparently in the data of Melchior et al. (1988) as well. Laboratory work thus provides the link to extend the Poincaré model to include viscous and nonlinear effects in order to interpret the gravimetric observations as core modes.     

利用云南水管仪观测资料检测地球自由振荡

利用云南省数字化水管仪的观测资料,采用功率谱密度估计方法,在没有对资料进行去固体潮处理的情况下,准确获得了2004年12月26日苏门答腊大地震激发的0S4～0S30基频球型自由振荡,并与前人的观测结果进行比较,同时对照了PREM模型的理论计算周期,发现水管仪观测与这三者符合得非常好,除0S4振型的观测周期和周期1、周期2、周期3的相对误差均大于0.3%外,其余的差别在3‰以下。研究表明,利用数字化水管仪观测资料的确可以提取到苏门答腊大地震激发的地球球型振荡,这就为地球自由振荡的研究提供了一种新的观测手段。     

Seasonal Changes in Nitrogen, Free Amino Acids, and C/N Ratio in Mediterranean Seagrasses

Abstract. Seasonal changes in nitrogen, free amino acids, and carbon were investigated in the three Mediterranean seagrasses Posidonia oceanica, Cymodocea nodosa , and Zostera noltii. Leaves, rhizomes, roots, as well as dead plant material were analysed separately. Highest N-concentrations were obtained in the winter months, regardless of species or plant part. In contrast to the other two species, the N-content in Posidonia was higher in the rhizomes than in the leaves.
In the investigated species, marked differences in the free amino acid (FAA) composition were detected between species: Proline, lacking in Posidonia , was the main component in Cymodocea. In Posidonia , FAA decreased from 320umol g^-1 (dry wt) in leaf sheaths to 1.5 umol g^-1 (dry wt) in the leaf tips. The function of proline as a possible storage and/or stress metabolite is discussed.
High C/N values in dead P. oceanica and C. nodosa rhizomes as well as in P. oceanica wrack seem to be related to considerable resistance to decomposition. Low C/N ratios did not increase in detached C. nodosa and Z. noltii leaves, which began to decompose shortly after detachment from the plants.