Orbital period analysis of eclipsing post-novae T Aurigae: Evidence of magnetic braking and an unseen companion

Four new CCD times of light minimum of T Aurigae are presented. The orbital period variation is analyzed by means of the standard O–C technique. The new times of light minimum indicate that a ～24 yr sine-like period variation superimposed on a secular orbital period decrease is obviously seen in the O–C diagram. However, the orbital period should increase because of mass transfer between components. In order to solve this apparent paradox, three possibilities including magnetic braking mechanism, which plays an important role in angular moment loss of binary, are proposed. The mass loss rate $\dot{M}={10}^{-10.4}{M}_{\odot }{\text{yr}}^{-1}$ is derived by assuming that the Alfvén radius of secondary is the same as that of the sun (i.e. $R_A?15R_{\odot }$). Using the observational relationship of ${\dot{M}}_{\mathit{mb}}-P_{\mathit{orb}}(h)$ (McDermott and Taam, 1989, Rappaport et al., 1983), the Alfvén radius of secondary is estimated as $R_A?1.9R_{\odot }$, which only requires a weak magnetic field in secondary. Since the brightness variations of T Aurigae caused by Applegate’s mechanism need large energy beyond the total radiant energy in the time interval of 24 yr, the third body light travel-time effect is the most likely explanation for the 24-yr variation. The third body may be a brown-dwarf star in case of the high orbital inclination.     

陆地沉积物对大洋缺氧事件的响应：六盘山群黑色页岩地球化学特征及其意义

通过对六盘山群中上部湖相沉积中一层黑色页岩年代（113.45~112.98 Ma）及其下部泥灰岩的元素地球化学特征研究发现,黑色页岩形成于干热而相对湿润气候背景下的缺氧还原环境中,与典型缺氧事件黑色页岩的地球化学特征基本一致,说明该黑色页岩记录了六盘山地区对全球白垩纪大洋缺氧事件OAE1b (约113～111 Ma)的响应,可能指示该期大洋缺氧事件是一次全球性的气候变化事件。     

Impacts of an improved low-level cloud scheme on the eastern Pacific ITCZ-cold tongue complex

A statistically-based low-level cloud parameterization scheme is introduced, modified, and applied in the Flexible coupled General Circulation Model (FGCM-0). It is found that the low-level cloud scheme makes improved simulations of low-level cloud fractions and net surface shortwave radiation fluxes in the subtropical eastern oceans off western coasts in the model. Accompanying the improvement in the net surface shortwave radiation fluxes, the simulated distribution of SSTs is more reasonably asymmetrical about the equator in the tropical eastern Pacific, which suppresses, to some extent, the development of the double ITCZ in the model. Warm SST biases in the ITCZ north of the equator are more realistically reduced, too. But the equatorial cold tongue is strengthened and extends further westward, which reduces the precipitation rate in the western equatorial Pacific but increases it in the ITCZ north of the equator in the far eastern Pacific. It is demonstrated that the low-level cloud-radiation feedback would enhance the cooperative feedback between the equatorial cold tongue and the ITCZ. Based on surface layer heat budget analyses, it is demonstrated that the reduction of SSTs is attributed to both the thermodynamic cooling process modified by the increase of cloud fractions and the oceanic dynamical cooling processes associated with the strengthened surface wind in the eastern equatorial Pacific, but it is mainly attributed to oceanic dynamical cooling processes associated with the strengthening of surface wind in the central and western equatorial Pacific.     

中国中温带东部生态地理区划的土壤指标

Eco-geographic regional system is formed by division or combination of natural features based on geographic relativity and comparison of major ecosystem factors (including biological and non-biological) and geographic zonality. In previous studies, soil types were often taken as a basis for soil regionalization. However, the quantitative characteristics of soil indicators are fitter than the qualitative ones of soil types for modern regionalization researches. Based on the second China’s national soil survey data and the provincial soil resource information, by principal analysis and discriminant analysis, this paper discusses the appropriate soil indicators as the complement of eco-geographic region indicator systems and the relationships between these soil indicators and soil types in regionalization. The results show that five indicators are used in eco-geographic zonality in mid-temperate zone of eastern China which are organic matter content, cation exchange capacity, pH, clay content and bulk density in topsoils. With a regression-kriging approach, the maps of soil indicators in mid-temperate zone of eastern China are compiled with a resolution of 1 km in every grid and the indicative meanings of these soil indicators are discussed. By cluster analysis it is proved that these soil indicators are better than the soil types and soil regionalization in delineating eco-geographic regions. Foundation: National Natural Science Foundation of China, No.40771016 Author: Liu Ye (1980–), Ph.D, specialized in integrated physical geography.     

中国西南纵向岭谷区孢粉空间组合对阻隔作用的指示意义

35 surface soil samples and 28 profile soil samples were collected in Longitudinal Range-Gorge Region, Southwest China. The distribution of pollen and spores and their relationship with the environment are analyzed. The results show that there are significant differences in pollen and spores taxa, amounts, dominant taxa and florae between the eastern and western flanks of the Ailao Mountain. There are more pollen and spores taxa, a greater amount and complexity on the western flank of the mountain than those on the eastern flank, while the dominant taxa are more centralized and prominent on the eastern flank of the Ailao Mountain. As for the plant florae distribution, there are significant differences in the number of taxa and composition between the eastern and the western flanks. The analysis of profile pollen and spores assemblage shows that its trends of variation are basically in accordance with the surface pollen and spores, which are also indicators of the environmental differences between the two flanks of the mountain. These significant spatial differences of pollen and spores are very close to the regional topography and climate difference. The mountain running perpendicular to the moisture-laden air flow serves as a barrier and the monsoon circulations the east and the west of the mountain result in different energy-moisture characteristics. We conclude that the main patterns of the pollen and spores can be attributed to the environmental differences.     

Precision estimation and geomorphological analysis based on the DEM generated by InSAR: Taking Damxung-Yangbajain area as an example

Digital elevation model (DEM) can be generated by interferometric synthetic aperture radar (InSAR). In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, using a pair of Europe remote-sensing satellite (ERS)-1/2 tandem SAR images acquired on 6 and 7 April 1996. A portion of the In- SAR-derived DEM is selected and compared with the 1:50 000 DEM to determine the precision of the InSAR-derived DEM. The comparison indicates that the root mean squared er...     

四川木里小震群活动特征研究

本文通过对四川木里地区地震震源位置的重新确定,反演了较大地震震源机制解,结果显示：①重定位后的小震群震中分布成带状,地震震源深度分布在0—12km范围内;②经过对震群空间分布进行仔细分析,认为其发震构造是小金河断裂西侧的一条NWW向分支断裂;③3次4.0级以上地震震源参数存在明显差异,浅源逆冲事件表现有受垂直方向应力（重力）作用的特征,走滑事件表现出与区域应力构造活动有关。     

低频振动台主要性能指标测试分析

为了更好满足地震计的振动测试需求,对振动台的波形失真度、横向运动比、台面不均匀度及稳定性等主要性能指标进行了测试分析.测试结果表明:该振动台具有较好的低频振动特性.利用低频标准套组对该振动台和中国计量科学研究院标准振动台进行比对分析,测试结果存在较小偏差.     

四川前陆盆地上三叠统须家河组物源区分析及其地质意义

为了深入认识四川前陆盆地须家河组沉积物源方向及物源区构造背景,对该盆地次级构造单元内须家河组砂岩碎屑组分、岩屑类型、重矿物组合特征、稀土元素和微量元素进行了分析。结果表明,盆地中的碎屑物源主要来自再旋回造山带,部分可能来自造山之前的混合区,不同的构造单元和层位存在不同物源区的特点：川西坳陷物源主要受龙门山逆冲推覆带控制;川东北坳陷物源主要受米仓山-大巴山逆冲推覆带控制;川东南坳陷物源受雪峰古陆控制,而川中古隆起物源则主要来自南部峨眉瓦山古陆。物源区具有大陆边缘向大陆岛弧转化的构造演化特点,须四期龙门山的逆冲推覆活动明显强于须二期。     

An enhanced engineering perspective of global climate systems and statistical formulation of terrestrial CO2 exchanges

This paper designs a comprehensive approach based on the engineering machine/system concept, to model, analyze, and assess the level of carbon dioxide (CO₂) exchange between the atmosphere and terrestrial ecosystems, which is an important factor in understanding changes in global climate. The focus of this article is on spatial patterns and on the correlation between levels of CO₂ fluxes and a variety of influencing factors in eco-environments. The engineering/machine concept used is a system protocol that includes the sequential activities of design, test, observe, and model. This concept is applied to explicitly include various influencing factors and interactions associated with CO₂ fluxes. To formulate effective models of a large and complex climate system, this article introduces a modeling technique that will be referred to as stochastic filtering analysis of variance (SF-ANOVA). The CO₂ flux data observed from some sites of AmeriFlux are used to illustrate and validate the analysis, prediction, and globalization capabilities of the proposed engineering approach and the SF-ANOVA technique. The SF-ANOVA modeling approach was compared to stepwise regression, ridge regression, and neural networks. The comparison indicated that the proposed approach is a valid and effective tool with similar accuracy and less complexity than the other procedures.