Steady state equilibrium condition of npe^± gas and its application to astrophysics     

Men-Quan Liu 《天体物理学报》2011,(1):91-102

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Gabbroic xenoliths from La Palma, Tenerife and Lanzarote, Canary Islands: evidence for reactions between mafic alkaline Canary Islands melts and old oceanic crust     

E. -R. Neumann  V. B. Srensen  S. L. Simonsen  K. Johnsen 《Journal of Volcanology and Geothermal Research》2000,103(1-4)

Gabbroic and hornblendite xenoliths from La Palma, Tenerife and Lanzarote fall into three main groups based on petrography and chemistry. One group (comprising all xenoliths from Lanzarote and some from La Palma) consists of highly deformed orthopyroxene-bearing gabbroic rocks that show a strong affinity to N-MORB and oceanic gabbro cumulates in terms of mineral chemistry and REE relations. However, they show mild enrichment in the most incompatible elements (particularly Rb+Ba±K) relative to intermediate and heavy REE, and their Sr–Nd isotope ratios fall within or close to the N-MORB field. The second group (60% of the xenoliths from La Palma) are gabbroic cumulates with zoned clinopyroxenes (Ti–Al-poor cores, Ti–Al-rich rims) and reaction rims of hornblende, biotite and clinopyroxene on other phases. Their trace-element and Sr–Nd isotope relations are in general transitional between N-MORB cumulates and Canary Islands alkali basalts, but they show strong enrichment in Rb, Ba and K relative to other strongly incompatible elements. The third group (comprising some xenoliths from La Palma and all those from Tenerife) are undeformed gabbroic and hornblendite rocks in which hornblende and biotite appear to belong to the primary assemblage. These rocks show strong affinities to Canary Islands alkali basaltic magmas with respect to mineral, trace-element, and Sr–Nd isotope chemistry. The first two groups are interpreted as fragments of old oceanic crust which have been mildly to strongly metasomatized through reactions with Canary Islands alkaline magmas. The reaction process is a combination of enrichment in elements compatible with biotite (and hornblende), and simple mixing between N-MORB cumulates and trapped alkaline magmas. The third group represents intrusions/cumulates formed from mafic alkaline Canary Islands magmas. Modeling indicates that locally up to 50% new material has been added to the old oceanic crust through reactions with ocean island basalts. Reactions and formation of cumulates do not represent simple underplating at the mantle/crust boundary, but have taken place within the pre-existing oceanic crust, and are likely to have significantly thickened the old oceanic crust.  相似文献   

A New Theory of Love Waves in Multi-layered Media with Irregular Interfaces   总被引：3，自引：0，他引：3  

Chen Xiaofei  Ge ZengxiDepartment of Geophysics  Peking University  Beijing  China 《中国地震研究》1999,(2)

In this article, we have derived a new and more general formulation of Love waves in arbitrarily irregular multi-layered media by using the global generalized reflection/transmission (abbreviated to R/T thereafter) matrices method developed earlier by Chen [17~20]. From the basic principle that the modal solutions are the non-trivial solutions of the free elastodynamic equation under appropriate boundary conditions, we naturally derived the characteristic frequencies and the corresponding distorted modes of Love wave in irregular multi-layered media. Moreover, we have derived the corresponding excitation formulation of Love waves in such laterally heterogeneous media by using the general solution of elastodynamic equation [17~20]. Similar to the result for laterally homogeneous layered structure, the Love waves radiated from a point source in irregular multi-layered media can be expressed as a superposition of distorted modes. Since the structure model used here is quite arbitrary, it can be used for so  相似文献   

Coulomb corrections to the equation of state of nuclear statistical equilibrium matter: implications for SNIa nucleosynthesis and the accretion-induced collapse of white dwarfs     

E. Bravo  D. García-Senz 《Monthly notices of the Royal Astronomical Society》1999,307(4):984-992

Coulomb corrections to the equation of state of degenerate matter are usually neglected in high-temperature regimes, owing to the inverse dependence of the plasma coupling constant, Γ, on temperature. However, nuclear statistical equilibrium matter is characterized by a large abundance by mass of large- Z (iron group) nuclei. It is found that Coulomb corrections to the ion ideal gas equation of state of matter in nuclear statistical equilibrium are important at temperatures T ≲5–10×10⁹ K and densities ρ ≳10⁸ g cm⁻³. At a temperature T =8.5×10⁹ K and a density ρ =8×10⁹ g cm⁻³, the neutronization rate is larger by ≳28 per cent when Coulomb corrections are included. However, the conductive velocity of a thermonuclear deflagration wave in C–O drops by ∼16 per cent when Coulomb corrections to the heat capacity are taken into account. The implications for SNIa models and nucleosynthesis, and also for the accretion-induced collapse of white dwarfs, are discussed. Particularly relevant is the result that the minimum density for collapse of a white dwarf to a neutron star is shifted down to 5.5–6×10⁹ g cm⁻³, a value substantially lower than previously thought.  相似文献   

HEIFE非均匀陆面上区域能量平衡研究   总被引：8，自引：1，他引：7  

马耀明  王介民  Massimo Menenti  Wim Bastiaanssen 《气候与环境研究》1997,2(3):293-301

卫星遥感在研究非均匀陆面上地－气间能量和水循环过程时有其独到的作用。本文介绍了一种利用陆地资源卫星ＴＭ资料进行非均匀陆面上区域能量平衡研究的参数化方案。以两个景的ＴＭ资料（１９９１年７月９日,夏季;１９９１年１０月２９日,近冬季）为个例,结合“黑河实验”（ＨＥＩＦＥ）期间的地面观测资料分析研究了实验区非均匀陆面上地表特征参数（地表反射率、标准化差值植被指数和地表温度）及能量平衡各分量（地表净辐射通量、土壤热通量、感热和潜热通量）的区域分布及季节差异,同时将所得的结果与地面观测的“真值”作了比较。结果表明：（１）由于黑河实验区下垫面状况十分复杂,戈壁、沙漠与绿洲交错分布,故在整个实验区内各地表特征参数及能量平衡各分量的分布范围亦比较宽;（２）地表特征参数及能量平衡各分量在实验区的绿洲、戈壁及沙漠上各有其特定的代表值;（３）地表能量平衡各分量的区域平均值在整个实验区内基本平衡;（４）夏季与近冬季的地表特征参数及能量平衡各分量的分布特征存在着显著差异。所得的这些结果与地面观测的“真值”和局地研究的结论基本一致。这些分析对非均匀下垫面中尺度模式陆面过程参数化方案的建立以及模式预报效果的检验都具有不可缺少的重要意义。  相似文献   

Synthesis,Characterization, and Application of Fe–Ni Bimetallic Nanoparticles for the Reductive Degradation of Nimesulide     

《洁净——土壤、空气、水》2017,45(1)

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2010智利Maule特大地震的同震效应   总被引：4，自引：0，他引：4       下载免费PDF全文

黄禄渊  张贝  瞿武林  张怀  石耀霖 《地球物理学报》2017,60(3):972-984

2010年智利Maule大地震是人类有观测记录以来第六大地震,基于高性能并行有限元方法,建立含地表地形和Moho面起伏的大规模非均匀椭球地球模型,计算了该地震同震效应,并根据库仑应力变化分析周围断层地震活动性和主震对余震的触发关系.结果表明:对于2010年Maule地震,地球曲率和层状结构对同震水平位移影响不可忽略,如果不采用球面分层模型,在低纬度远场可能会造成位移和应变量值均被低估,在高纬度远场可能会造成位移被夸大而应变被低估.如果不考虑介质横向不均匀和地形,同震应力降被显著低估,近场同震东西向应力变化误差最高95.4%,南北向应力变化误差最高90.8%.Illapel地区库仑应力变化约10 kPa,相当于15年构造积累,Maule地震加速了2015年Illapel地震发生.以最优破裂方向投影得到库仑应力变化,经统计70.9%余震落在库仑应力变化量值大于10 kPa区域.本次特大地震触发了Pichilemu附近M_w6.9和M_w7.0两次正断型余震.  相似文献   

异构传感器网络密钥管理框架研究     

马春光  楚振江  王九如  王慧强 《武汉大学学报(信息科学版)》2010,(5)

给出了异构传感器网络(HSN)节点异构和网络异构的定义,分析了HSN中的异构性因素。对HSN中的物理因素和密钥管理协议进行了细粒度的刻画,提出了一种多维度的HSN密钥管理框架模型,为进一步研究密钥管理协议提供结构支撑。仿真分析验证了模型的正确性和有效性。  相似文献   

Differences in gravity‐dominated unsaturated flow during autumn rains and snowmelt     

H. K. French  S. E. A. T. M. van Der Zee  A. Leijnse 《水文研究》1999,13(17):2783-2800

Five tracer experiments have been performed in a coarse‐textured soil near the new main airport at Gardermoen, Norway. In two lysimeter walls, 30 and 40 measuring points form the basis for spatial moment calculations. Although experiments were performed under different meteorological conditions (autumn and snowmelt) and at two different sites, the ratios of centres of vertical mass over cumulative infiltration were of the same order of magnitude, indicating a gravity‐dominated flow. Two‐dimensional transport simulations with SUTRA (Voss, 1984), with a priori estimated input parameters and random fields of soil hydraulic properties revealed a relatively good agreement with the experimental results. Three possible sources of heterogeneity affecting the vertical displacement of solute during snowmelt were identified: variability of soil physical properties, soil surface elevations and variability of ground frost during the melting period. To obtain accurate predictions, soil heterogeneity was the most important factor to characterize for the coarse‐textured soil under consideration. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

盐度降低对长心卡帕藻原初光化学反应的影响   总被引：3，自引：1，他引：2       下载免费PDF全文

黄园  刘建国  庞通  李俊  林伟 《海洋学报》2010,32(3):146-152

为探讨大量降雨如何导致热带产胶海藻长心卡帕藻死亡,通过快速叶绿素荧光诱导动力学曲线分析,研究了盐度降低对热带产胶海藻长心卡帕藻光化学反应的影响,结果表明,盐度降低对PSⅡ反应中心、供体和受体侧的光化学过程产生不同程度的影响。盐度为28时,虽然反应中心开放程度下降11%,受体侧PQ库减小,QA被还原次数下降,反应中心吸收光能出现下降同时热耗散能量出现增加,但是单位面积反应中心RC/CS0,RC/CSm数量显著增加,单位反应中心(或面积)用于电子传递能量都增加,因此最大光能转化效率未降低,光合性能指数甚至增加。上述结果意味着虽然盐度下降到28改变了长心卡帕藻光化学过程,但并没有严重影响到光合作用效率,属于可逆胁变。盐度降低到22时,长心卡帕藻反应中心吸收、捕获和用于电子传递的能量均下降,但是热耗散能上升,反应中心受体侧PQ库和QA被还原次数均显著下降,向反应中心PSⅠ传递的电子受阻,即盐度低于22时长心卡帕藻未有效转化所吸收光能,过剩激发能对光合机构产生损伤,藻体光合开始发生不可逆胁变。当盐度为18时,该藻PSⅡ开放的反应中心数量大大减少,单位面积内电子传递能量也减少,其最大光能转化效率和光合性能指数均明显下降,因此盐度低于18时藻体不可避免地死亡。  相似文献