Forced secondary resonances at the 3 : 1 commensurability     

Yi-Sui Sun  Ji-Lin Zhou  Tian-Ling Zhang  Chong-Qing Cheng 《Celestial Mechanics and Dynamical Astronomy》1994,59(4):313-325

For the 3 : 1 Jovian resonance problem, the time scales of the two degrees of freedom of the resonant Hamiltonian are well-separated [5]. With the adiabatic approximation, the solution for the fast oscillations can be found in terms of the slowly varying variables. Thus the rapidly oscillating terms in the slow oscillation equations can be treated as forced terms. We refer to the resonance between the forcing and intrinsic frequencies as a forced secondary one in this paper. We discuss the forced secondary resonances in asteroidal motion at the 3 : 1 commensurability by using Wisdom's method. The results show that the orbits situated originally near the resonance will leave the neighbourhood of resonance and tend to the separatrices and critical points for different energies, respectively. We have not found any stochastic web as expected in this case. Moreover, we study the problem of validity on the approximation of a system.The Project Supported by the National Natural Science Foundation of China.  相似文献   

Isolation,purification and characterization of the hydrogen evolution promoting factor of hydrogenase ofSpirulina platensis     

Gu Tian-qing  Zhang Hui-miao  Sun Shi-hua 《中国海洋湖沼学报》1996,14(1):27-30

A component (s-factor) with obvious promoting effect on hydrogen evolution of hydrogenase has been isolated and extracted from a cell-free preparation ofSpirulina platensis. The effect of the s-factor in the reaction system is similar to that of Na₂S₂O₄, but is coupled with light. The s-factor has the maximum absorption peak at 620 nm in the oxidized state, at 590 nm in the reduced state. The partially purified s-factor showed two bands by SDS-PAGE and is distinctly different from phycocyanin, which has no change of oxidized state and reduced state absorption spectra, and also has no promoting effect on hydrogenase ofSpirulina platensis under the light. The research supported by the NSFC.  相似文献   

关联指数误差和样本容量     

吴云  周硕愚  孙建中 《大地测量与地球动力学》1994,(1)

根据关联指数的定义，推导了ＧＰ法计算关联指数时的观测数据误差与关联指数误差的关系，导出了任意两个嵌入空间维上关联指数之差的表达式，并提出了一种确定样本容量限的方法。  相似文献   

ISO SWS Spectroscopy of Proto-Planetary Nebulae     

Bruce J. Hrivnak  Kevin Volk  Sun Kwok 《Astrophysics and Space Science》1997,255(1-2):477-478

We are obtaining low- (SWS01) and medium-resolution (SWS06) spectra of PPNe to investigate spectral features arising in these transitional objects. Three sources with the 21 μm feature have been confirmed, one new source found, and evidence of some substructure seen. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

洱海近区非潮汐重力变化的研究     

翦大西  孙少安  刘力 《大地测量与地球动力学》1993,(3)

本文给出了洱海水体变化对局部重力场影响的解析式和量级,并且将理论结果与实测的水文、流动重力及定点重力分析结果作了比较,结果表明:影响的程度因距洱海的距离而异。在台站重力测量中,由水体变化产生的干扰淹没在零漂之中(约占每日零漂量的2％),潮汐主频段上没有明显的干扰信号;而对流动重力测量,在水体变化大的情况下,部分测点所产生的变化可以达到10×10~(-8)m/s~2。  相似文献   

Contemporary processes of environmental information in the atmosphere-glacier-runoff system in an area of typical monsoon temperate glacier     

He  Yuanqing  Yao  Tandong  Zhang  Xiaojun  Chen  Tuo  Yang  Meixue  Sun  Weizhen  Li  Fengxia 《中国科学:地球科学(英文版)》2001,44(1):275-283

Sampling was carried out at Baishui No. 1, the largest glacier on Mt. Yulong, China, during the summers of 1999 and 2000, to investigate the spatial variations of oxygen isotopes in the atmosphere-glacier-river system. The results confirm that there is an inverse relation between the oxygen isotopic composition of precipitation and air temperature/precipitation amount. This suggests that a strong “precipitation amount effect” exists in this typical monsoon temperate-glacier region. There are marked differences of the δ¹⁸O values of winter-accumulated snow, glacial meltwater, summer precipitation and the glacier-fed river water. Spatial and temporal variations of isotopic composition are controlled by climatic conditions. Isotopic fractionation and differentiation occur during phase changes, snow-to-ice and ice-to-meltwater transformations, and runoff processes. Variations of stable isotopes in glacier runoff can indicate variations of sources of supply, as well as different discharge-related processes. Ionic changes occur as a result of meltwater contact with glacier bed materials.

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Sea-Level Change Over the China Sea and Its Vicinity Derived from 25-Year T/P Series Altimeter Data     

Jianhua Wan  Qinting Sun  Shanwei Liu  Yinlong Li 《Journal of the Indian Society of Remote Sensing》2018,46(12):1939-1947

The characteristics of sea-level change in the China Sea and its vicinity are studied by combining TOPEX/Poseidon (T/P), Jason-1, Jason-2, and Jason-3 altimeter data. First, the sea-surface height is computed by using monthly data via collinear adjustment, regional selection, and crossover adjustment. The sea-level anomaly (SLA) from October 1992 to July 2017 is calculated based on the difference that is obtained by the value derived from the inverse distance weighting method to interpolate the CNES_CLS15 model value at a normal point. By analyzing the satellite data at the same time in orbit, three mean bias groups over the China Sea and its vicinity are obtained: the difference between T/P and Jason-1 is ??11.76 cm, the difference between Jason-1 and Jason-2 is 9.6 cm, and the difference between Jason-2 and Jason-3 is 2.42 cm. To establish an SLA series for 25 years in the study area, the SLAs are corrected. Mean rate of sea-level rise of the Bohai Sea, Yellow Sea, East China Sea, and South China Sea of 4.87 mm/a, 2.68 mm/a, 2.88 mm/a, and 4.67 mm/a, respectively, is found by analyzing the series of SLAs.  相似文献   

南宁膨胀土持水性能的温度效应及微观机制     

曾召田  崔哲旗  孙德安  姚志  潘斌 《岩土力学》2023,(8):2177-2185

采用蒸汽平衡法测定了4种温度(T=5、25、40、60℃)条件下Whatman No.42滤纸的率定曲线,建立了考虑温度影响的双线性率定曲线方程,发现滤纸的持水性能随温度升高而降低,且温度对率定曲线高吸力段滤纸持水性能的影响要弱于低吸力段。在此基础上,以南宁膨胀土为研究对象,使用滤纸法测定了不同温度作用下膨胀土试样的土-水特征曲线。试验结果表明,随着温度的升高,膨胀土持水性能下降,但温度的影响幅度会随着吸力的增大而减弱,当基质吸力达到40MPa时,不同温度下试样的体积含水率并没有明显变化,即此时温度对膨胀土的持水性能变化几乎无影响。为解释上述宏观现象,选取部分试样进行了压汞试验和吸附结合水试验,并根据试验结果从土体中各相及各相界面相互耦合作用的物理机制角度阐述了南宁膨胀土持水性能的温度效应及微观机制。  相似文献   

近地表隐伏断层地震波场响应特征与初至波成像应用研究     

孙茂锐 《地质与勘探》2023,59(5):1043-1053

近地表隐伏断层直接影响工程安全施工。通过构建浅覆盖层下方陡立界面断层数值模型,分析近地表隐伏断层地震波场的传播与转换规律。通过工程实测数据验证了数值模拟波场响应特征的可靠性,并利用初至波走时层析成像技术对地下介质波速进行成像。研究结果表明：(1)初至波转换形成的断点绕射波具有1频率升高、速度突变的特点,可清晰指示测区内断裂带的存在,可作为现场数据采集时断层的直观反映;(2)工程实测中通过原始波形到时、频率信息可初步判断断层的存在,基于射线追踪的初至波层析成像结果与后期钻孔揭露情况基本吻合,说明初至波层析成像在浅层地震勘探中的实用性;(3)接收测线排列内布设震源的方式,两侧震源延拓距离短,无需额外为震源激发提供场地,在工程施工中具有经济、快速、高效的特点,可作为野外复杂地表条件地下浅层结构探测的有效观测系统使用。  相似文献   

Mantle metasomatism and generation of Early Permian ultramafic rocks in northern North China CratonSCIEI北大核心CSCD     

王志伟  孙瑜欣  朱泰昌  徐引  刘剑波  张立剑  李灿清  耿晓磊 《岩石学报》2023,(5):1387-1404

华北克拉通北部高寺台晚古生代环状杂岩体是一套富单斜辉石的超镁铁质岩,是研究华北北部地幔碳酸盐化熔体交代作用的理想对象,同时也是华北克拉通北部晚古生代岩浆活动与深部碳循环联系的纽带。作者在岩体西部边缘识别出一套早二叠世早期富铁角闪单斜辉石岩,形成时代为297.8±3.4Ma。结合岩体东部辉石岩早泥盆世和早石炭世的成岩年龄,表明高寺台超镁铁质杂岩体可能是晚古生代多期岩浆侵位的产物。其次,高寺台环状超镁铁质杂岩体缺少大面积辉长岩和闪长岩、硫化物和Cu-Ni-PGE矿化,单斜辉石成分具有裂谷带堆晶岩矿物特征,角闪石也具有相对低的结晶温度(933~947℃)和压力(287~323MPa)及水含量(4.06%~5.10%),而且区域上尚未发现同期环状杂岩体和蛇绿岩,与岛弧拼贴到陆块后沿俯冲带延伸数万米侵位的阿拉斯加型环状杂岩体明显不同。另外,前人的研究显示,与铬铁矿中富镁单斜辉石包裹体平衡的苦橄质母岩浆显示出OIB的特征,具有强烈的重稀土分馏、富Nb和高Nb/La,异常高的Ca/Al和(La/Yb)N,低的Ti/Eu、Zr/Sm和Hf/Sm,这些特征都表明苦橄质母岩浆起源于石榴石相软流圈地幔,且源区遭受过显著的碳酸盐熔体交代。单斜辉石岩中单斜辉石及角闪石成分及其平衡岩浆成分记录了母岩浆与岩石圈地幔相互作用后的岩浆演化过程,也显示出比母岩浆弱的源区碳酸盐熔体交代印记。此外,岩浆房在地壳浅部经历了多期深部岩浆补给和富铁熔体贯入,同时带来热量和挥发分,触发晶粥体活化,促进了岩浆的上升运移。高寺台环状超镁铁质杂岩体具有板内成因特征,可能是陆内岩石圈伸展的产物。华北克拉通北部晚石炭世-早二叠世三个岩浆事件峰期很好地对应着全球三次升温和CO_(2)回升事件,岩石圈伸展能有效促进强烈的中酸性岩浆活动及起源于碳酸盐化地幔的基性岩浆释放出大量的CO_(2),它们可能是晚石炭末期-早二叠世早期全球大气CO_(2)回升的贡献者之一。  相似文献