The Relationship between Radio Luminosity and Core-Dominance Parameter for XBLs     

Yong-Xiang Wang  Y. Liu  Fei-Peng Pi  Jiang-He Yang 《Journal of Astrophysics and Astronomy》2011,32(1-2):59-60

In this work, we investigate the correlation between the luminosity and the core-dominance parameter for a sample of X-ray selected BL Lacertae objects (XBLs), and found that the extended luminosity is strongly anti-correlated with the core-dominance parameter while the core (or the total) luminosity is not correlated with the core-dominance parameter. If this is the case, then we can expect that the lower extended luminosity XBLs and their core luminosity is relatively higher. This can be explained by a relativistic beaming model since in this case, the viewing angle is smaller and the emissions dominate the extended emissions. Therefore, the anti-correlation is in fact the result of the relativistic beaming model.  相似文献   

吉林省浅层地热开发利用适宜性     

祖秉新  孟凡利  张丕  曹葛  孙晓芳 《吉林地质》2013,(3):105-107,123

本文对吉林省浅层地热开发利用的适宜性进行了论证。概括地阐述地质及水文地质条件、地热分类与其形成机制,指出浅层地热的特点和开发利用现状。全面地分析浅层地热开发利用的适宜条件,为浅层地热的利用发挥建设性作用。  相似文献   

Seismo-ionospheric precursory anomalies detection from DEMETER satellite data based on data mining     

Y. D. Wang  D. C. Pi  X. M. Zhang  X. H. Shen 《Natural Hazards》2015,76(2):823-837

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Lateral erosion of the Sacramento River,California (1942–1999), and responses of channel and floodplain lake to human influences     

M. Michalková  H. Piégay  G.M. Kondolf  S.E. Greco 《地球表面变化过程与地形》2011,36(2):257-272

This study focused on a spatial and temporal analysis of the active channel and associated floodplain lakes using aerial photographs spanning five decades (1942, 1962, 1985, 1999) over a 140 km long reach of the Sacramento. Planimetric changes were analysed longitudinally and temporally to highlight the spatial structures and their evolution through time. The results underline complex changes and space–time pattern in bank erosion, channel length and active channel width. The bank erosion and also channel lengthening were higher between 1962 and 1985 than in the two periods studied before and after. Active channel width significantly decreased from 1942 to 1999; partly progressively from upstream to downstream with local widening whatever the studied periods. Similarly the floodplain lakes observed before 1942–1962 were significantly different in size and geometry from those which appeared during the most recent period. The creation of lakes is less frequent after the 1940s, with a secondary peak of occurrence during the 1962–1985 period. The interpretation of these changes is complex because of various human pressures acting over different time scales (bank protection, flow diversion, sediment starvation, land‐use changes) and various natural influences (flood sequences through out the period, geological setting). The findings are discussed by comparison with previous work, and highlight the important effect of dam impact on peak flow and sediment starvation modifying longitudinally hydraulic conditions within the channel, but also the increase in riprap protection which induced change in bank erosion, channel planimetry and floodplain lake characters (geometry, frequency of renewal). Variation in flood intensities is also observed as having positive effects on the bank erosion pattern. Secondarily, land‐use changes also controlled bank erosion intensity. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Multiproxy analysis of a new terrestrial and a marine Cretaceous-Paleogene (K-Pg) boundary site from New Zealand     

Embaie Ferrow  Vivi Vajda  Christian Bender Koch  Pi Suhr Willumsen 《Geochimica et cosmochimica acta》2011,75(2):657-672

An integrated study of palynology, Mössbauer spectroscopy, mineralogy and osmium isotopes has led to the detection of the first K-Pg boundary clay layer in a Southern Hemisphere terrestrial setting. The K-Pg boundary layer was independently identified at centimetre resolution by all the above mentioned methods at the marine K-Pg boundary site of mid-Waipara and the terrestrial site of Compressor Creek (Greymouth coal field), New Zealand. Mössbauer spectroscopy shows an anomaly of Fe-containing particles in both K-Pg boundary sections: jarosite at mid-Waipara and goethite at Compressor Creek. This anomaly coincides with a turnover in vegetation indicated by an interval dominated by fern spores and extinction of key pollen species in both sections. In addition to the terrestrial floristic changes, the mid-Waipara section reveals a turnover in the dinoflagellate assemblages and the appearance of global earliest Danian index species. Geochemical data reveal relatively small iridium enrichments in the boundary layers of 321 pg/g at mid-Waipara and 176 pg/g at Compressor Creek. Unradiogenic ¹⁸⁷Os/¹⁸⁸Os values of the boundary clay reveal the presence of a significant extraterrestrial component. We interpret the accumulation of Fe nano-phases at the boundary as originating from both the impactor and the crystalline basement target rock. The goethite and jarosite are interpreted as secondary phases formed by weathering and diagenesis. The primary phases were probably controlled by the initial composition of the vapor plume and condensation kinetics rather than condensation thermodynamics. This investigation indicates that identification of Fe in nano-phases by Mössbauer spectroscopy is an accurate and cost-effective method for identifying impact event horizons and it efficiently complements widely used biostratigraphic and geochemical methods.  相似文献   

Mission design,operation and exploitation of the gravity field and steady-state ocean circulation explorer mission   总被引：6，自引：3，他引：3  

Rune?FloberghagenEmail author  Michael?Fehringer  Daniel?Lamarre  Danilo?Muzi  Bj?rn?Frommknecht  Christoph?Steiger  Juan?Pi?eiro  Andrea?da?Costa 《Journal of Geodesy》2011,85(11):749-758

The European Space Agency’s Gravity field and steady-state ocean circulation explorer mission (GOCE) was launched on 17 March 2009. As the first of the Earth Explorer family of satellites within the Agency’s Living Planet Programme, it is aiming at a better understanding of the Earth system. The mission objective of GOCE is the determination of the Earth’s gravity field and geoid with high accuracy and maximum spatial resolution. The geoid, combined with the de facto mean ocean surface derived from twenty-odd years of satellite radar altimetry, yields the global dynamic ocean topography. It serves ocean circulation and ocean transport studies and sea level research. GOCE geoid heights allow the conversion of global positioning system (GPS) heights to high precision heights above sea level. Gravity anomalies and also gravity gradients from GOCE are used for gravity-to-density inversion and in particular for studies of the Earth’s lithosphere and upper mantle. GOCE is the first-ever satellite to carry a gravitational gradiometer, and in order to achieve its challenging mission objectives the satellite embarks a number of world-first technologies. In essence the spacecraft together with its sensors can be regarded as a spaceborne gravimeter. In this work, we describe the mission and the way it is operated and exploited in order to make available the best-possible measurements of the Earth gravity field. The main lessons learned from the first 19 months in orbit are also provided, in as far as they affect the quality of the science data products and therefore are of specific interest for GOCE data users.  相似文献   

拉萨岩土工程勘察回顾     

刘玉德  孙桂林  祖秉新  张丕  艾云峰 《吉林地质》2011,30(2):116-120

本文论述勘查区地质、水文地质条件和工程地质特征.通过岩土工程勘察和实地调查,该区一是地形险峻、地质环境复杂.二是气象、水文条件多变.在极端恶劣的环境完成4项优秀工程地质勘察成果报告,关键在于岩土工程勘察过程中进行了实地调研和资料收集等工作,才能取得较理想的效果.  相似文献   

Pollutant association with suspended solids in stormwater in Tijuana,Mexico   总被引：1，自引：1，他引：0  

F. T. Wakida  S. Martinez-Huato  E. Garcia-Flores  T. D. J. Piñon-Colin  H. Espinoza-Gomez  A. Ames-López 《International Journal of Environmental Science and Technology》2014,11(2):319-326

Stormwater runoff from urban areas is a major source of many pollutants to water bodies. Suspended solids are one of the main pollutants because of their association with other pollutants. The objective of this study was to evaluate the relationship between suspended solids and other pollutants in stormwater runoff in the city of Tijuana. Seven sites were sampled during seven rain events during the 2009–2010 season and the different particle size fractions were separated by sieving and filtration. The results have shown that the samples have high concentration of total suspended solids, the values of which ranged from 725 to 4,411.6 mg/L. The samples were analyzed for chemical oxygen demand, total phosphorus, total nitrogen, and turbidity. The results show that most of the particles in suspended solids are in the particle fraction between 10 and 62 μm. A high association between the concentrations of suspended solids was found for chemical oxygen demand, phosphorus, and turbidity but not for total nitrogen.  相似文献   

中国海洋旅游安全事故时空特征分析     

王璐  皮常玲  郑向敏 《热带地理》2022,42(7):1148-1157

为预防和减少海洋旅游安全事故,运用卡方列联表分析与残差检验、时间强度指数、地理集中指数和不平衡指数分析中国海洋旅游安全事故的类型、特征与时空分布规律。研究发现：1）中国海洋旅游安全事故类型主要分为溺水、被困、交通事故、自杀、意外受伤、动物咬伤、疾病突发、火灾、食物中毒等9种。2）事故发生的主导因素存在类型差异,涉事旅游者个体特征、旅游活动与事故发生的关联性较高。3）事故在大（年）、中（月）、小（日）时间尺度分布呈现差异性和集中性。事故发生数量呈上升趋势,7―8月为高发期,5―6、10月为次发期,下午（T 14:00―18:00）为一日高发时段,上午（T 08:00―12:00）和晚上（T 18:00―21:00）为一日次发时段。4）事故在大（海洋旅游圈）、小（海洋旅游城市）、微（海洋旅游活动点）空间尺度分布呈现聚集性和不平衡性。其中,大空间尺度集中在闽台海峡西岸区域和环渤海区域,小尺度（闽台海峡西岸区域为例）集中在厦门、泉州和福州,微尺度集中在沙滩、海礁与海上区域。因此,建议从高发事故类型及其发生特征、时空分布规律等方面强化安全防控与监管工作,预防和减少海洋旅游安全事故发生。  相似文献   

含平流(advection)的热单温吸积流的径向结构     

刘效庸  杨丕博  杨兰田  陈韶丽 《中国天文和天体物理学报》1997,(3)

本文在小粘滞参数（α＝０．１）、低吸积率的条件下，借助含平流的热吸积流的自相似解，考虑非热正负电子对产生，采用分两个区域分别求解然后对接的方法，研究了含平流的热单温吸积流的径向结构．证实了热吸积流所具有的一些显著特征和基本性质，同时得到一些新的结果：含平流的热吸积流存在一个临界半径ｒｃｒ；明确指出含平流的热吸积流的辐射冷却率与中心天体的质量成平方反比关系；提出正负电子对过程对含平流的热吸积流的辐射过程有显著影响．  相似文献