7个月周期极移的非线性动力机制     

王文均 《武汉大学学报(信息科学版)》2001,26(2):150-154

从滞弹性阻尼形变摄动造成CW频率调制假设出发，对CW的共振激发模型加上参数的时变调制，变成了参数共振模型。经正演计算发现，参数共振模型完全符合CW的实际，表明滞弹性阻尼形变摄动造成频率的3％调制，进一步使得CW振幅调制可达70％以上。这一参数共振模型是一个非线性动力系统，在非线性情况下，运动将发生分岔，即多解。  相似文献   

川滇地区7级大震前中强震震源机制变化   总被引：7，自引：0，他引：7  

王绍晋  付虹  卫爱民  龙晓帆 《地震研究》2001,24(2):99-108

分析了 70年代以来 ,川滇地区发生的 8次 7级大震前 5年内 ,发生在大震孕震区和震源区内的中强震震源机制解时空分布。结果表明 ,最早中强震发生在大震震源区或其附近 ,其发震应力场与区域构造应力场一致 ,与大多数大震发震应力场一致或接近。大多数中强震震源破裂特征与大震明显不同。之后有多次中强震发生在距大震震源区较远的大震孕震区内其他地方 ,它们的发震应力场往往经历了与区域构造应力场和大震应力场一致与不一致的多次交替变化。大震前最后 1个中强震也发生在距大震震源区较近的地方 ,其发震应力场与大震发震应力场明显不一致 ,偏转了 30°～ 5 0° ,或更多 ,大多数也与区域构造应力场不一致 ,有的中强震发震断裂破裂特征与大震不一致。大震前中强震震源机制的变化 ,反映了大震孕育过程的不同阶段 ,区域构造应力场的时空调整变化和增强过程 ,以及由此引发的构造断裂异常活动 ,揭示出与大震发生有关的应力场和震源破裂特征信息  相似文献   

Environmental study of the Amman-Zerqa Basin Jordan     

M. Awad 《Environmental Geology》1997,33(1):54-60

 Rapid population growth, urbanization expansion of rural settlements, industrial activity, intensively irrigated agriculture, pesticides consumption, and continuous dumping of hazardous waste in the Amman-Zerqa Basin since 1967 are the major factors threatening the quality of the environment. Thus, an environmental recommendation is proposed to protect the environment and water resources in the study area. The chemical analysis of the springs in the study area showed salinity increasing with time, which indicates water pollution affecting these springs. The laboratory analyses indicated that the quality of the treated waste water of Khirbet Es-Samra Treatment plant conforms to the World Health Organization (WHO) standards from the chemical, physical, and the microbiological point of view. Toxic elements such as cadmium identified in the surface water flow of the basin are in concentrations higher than those recommended by WHO Received: 30 January 1997 · Accepted: 30 June 1997  相似文献   

Very hot,very shallow hydrothermal dolomitization: An example from the Maritime Alps (north‐west Italy–south‐east France)          下载免费PDF全文

Luca Barale  Carlo Bertok  Namam Salih Talabani  Anna d'Atri  Luca Martire  Fabrizio Piana  Alain Préat 《Sedimentology》2016,63(7):2037-2065

In the Maritime Alps (north‐west Italy – south‐east France), the Middle Triassic–lowermost Cretaceous platform carbonates of the Provençal Domain locally show an intense dolomitization. Dolomitized bodies, irregularly shaped and variable in size from some metres to hundreds of metres, are associated with tabular bodies of dolomite‐cemented breccias, cutting the bedding at a high angle, and networks of dolomite veins. Field and petrographic observations indicate that dolomitization was a polyphase process, in which episodes of hydrofracturing and host‐rock dissolution, related to episodic expulsion of overpressured fluids through faults and fracture systems, were associated with phases of host‐rock dolomitization and void cementation. Fluid inclusion analysis indicates that dolomitizing fluids were relatively hot (170 to 260°C). The case study represents an outstanding example of a fossil hydrothermal system, which significantly contributes to the knowledge of such dolomitization systems in continental margin settings. The unusually favourable stratigraphic framework allows precise constraint of the timing of dolomitization (earliest Cretaceous) and, consequently, direct evaluation of the burial setting of dolomitization which, for the upper part of the dolomitized succession, was very shallow or even close to the surface. The described large‐scale hydrothermal system was probably related to deep‐rooted faults, and provides indirect evidence of a significant earliest Cretaceous fault activity in this part of the Alpine Tethys European palaeomargin.  相似文献   

Discussion on the Use of 7Be to Estimate Soil Erosion Rates     

Shi Zhonglin  Wen Anbang  Yan Dongchun  Long Yi  Zhou Ping 《地球科学进展》2016,31(9):885-893

⁷Be is a naturally occurring cosmogenic radionuclide produced in the stratosphere and troposphere as a result of cosmic ray spallation of nitrogen and oxygen. The constant fallout via precipitation and short half-life (53.3 days), coupled with shallow depth distribution in soil profile (~2 cm) provide the unique advantages for its application as a soil and sediment tracer over short timescales, such as a single storm or short period of extreme rainfall. With the climate change and increasing rainfall events, the ⁷Be tracing method will exhibit wide application prospect in future. To date, however, this technique is still in its infancy and some important assumptions have not yet been effectively validated. Consequently, the use of ⁷Be to document soil erosion rates has been limited. This contribution briefly reviews the history and current status relating to this tracing method. In addition, the basic principles and recent research progresses in conversion models for use of ⁷Be measurements to estimate soil redistribution rates are introduced. The key assumptions and uncertainties of the technique, as well as the effects of the vegetation interception and particle size selectivity are discussed. Additionally, some new investigation directions are provided, including the assumption validation and uncertainty analysis, the impact of vegetation interception, the extending of spatial and temporal scales, and the development of new conversion models.  相似文献   

构建独立坐标系与CGCS2000坐标系转换关系的研究     

刘万华  叶水全 《测绘与空间地理信息》2016,(1):217-219

西部某独立坐标系(下文简称独立系)建立于20世纪50年代,以辖区内2处1954年北京坐标点为起算点,并投影至当地平均高程面的二维平面坐标系。独立坐标系无确切的数学模型,与通用质心坐标系(如WGS84、CGCS2000)之间的转换一般通过平差完成。本文研究运用二维非线性最小二乘重算参数模型(a,f)和Bursa七参数模型,建立了独立坐标系与CGCS2000坐标系之间的转换关系。  相似文献   

房山周口店车厂北沟泥石流特征及防治     

黄来源  韩建超  季为  张亮  齐干 《城市地质》2016,(2):48-55

泥石流是北京地区危害性严重的地质灾害之一,作为北京"7·21"特大暴雨灾害受灾最为严重的区县,房山区近现代泥石流一直比较活跃,灾情严重。为了查清房山区"7·21"特大暴雨后典型泥石流灾害发育和运动特征,本文选取了车厂村北沟作为样本,通过采用现场调查、槽探、岩土测试等方法,对主沟整体流域进行了系统研究。从而查清了形成区的物源类型和可移动物源储量,掌握了全流域的沟道形态特征;通过对堆积区堆积形态和堆积物调查分析,论述了主沟水动力特征和冲淤特征;根据相关规范,计算得出了泥石流的动力学参数。分析了泥石流形成机理,进行了危险性评价,提出了防治对策。  相似文献   

Cell responses to xenobiotics: comparison of MCF7 multi-drug- and mussel blood cell multi-xenobiotic-defense mechanisms     

Marin M  Legros H  Poret A  Leboulenger F  Le Foll F 《Marine environmental research》2004,58(2-5):209-213

Multi-drug resistance (MDR) in MCF7 breast cancer cells and multi-xenobiotic resistance (MXR) in mussel (Mytilus edulis) blood cells (MBC) are well known mechanisms that contribute to the decrease in intracellular concentrations of many unrelated but cytotoxic compounds. In the present work, we have carried out comparative investigations of the MDR/MXR protective mechanisms using a rapid colorimetric assay for cell viability and calcein accumulation for MDR/MXR activities. These studies were performed using cultured MCF7 and MBC before and after in vitro exposure to xenobiotics. Our results indicate that a 5-day exposure to doxorubicin or vincristine decreased calcein accumulation in MBC which is consistent with an induction of multi-xenobiotic resistance. The increase in calcein accumulation provoked by 1-h treatment with 50 microM verapamil was much lower in MBC when compared to the P-glycoprotein overexpressing MCF7 cell line. We conclude that such microplate assays could be used in primary cultures of MBC to estimate the effects of various chemicals on MXR activity.  相似文献   

鄂尔多斯盆地庆城地区延长组7段致密油特征及油源分析     

屈童  高岗  梁晓伟  孙明亮  尤源  李涛涛  冯顺彦  刘艳妮  费国勇 《地质论评》2023,69(1):2023010006-2023010006

鄂尔多斯盆地三叠系延长组7段(长7段）半深湖—深湖相优质油源岩是油气的重要来源,包括黑色页岩和暗色泥岩,作为盆地重要的供烃源岩一直是研究的热点。为了明确不同烃源岩的贡献及油气来源,通过对庆城地区长7段致密油特征进行分析,对原油进行精细划分,并对源岩有效性进行分析,进一步明确油源对应关系,研究表明,庆城地区长7段黑色页岩和暗色泥岩均对油气成藏有贡献,其中黑色页岩贡献最大,长73段暗色泥岩次之,长72和长71段暗色泥岩贡献较小;原油为低密度、中—低黏度和低凝固点的轻质油。根据生标物特征将原油划分为3类,A类原油具有低C30重排藿烷/C29藿烷、低C29Ts/C29藿烷、低Ts/Tm的特征,由黑色页岩贡献,主要分布于长71段;C类原油具有高C30重排藿烷/C29藿烷、高C29Ts/C29藿烷、高Ts/Tm的特征,主要由暗色泥岩贡献,数量较少且分布局限;B类油各项生标物参数均居中,为A、C类原油的混合,主要分布于长72段。由于黑色页岩生烃时间比暗色泥岩早,且原油黏度和密度更低,因此黑色页岩先生成低黏度A类原油易于向长72和长71段运移,而暗色泥岩后生成的C类原油主要近源富集与A类油混合分布于长72段,从而形成的A类油主要分布于长71段,B类油主要分布于长72段,而C类油分布局限的格局。这对下一步勘探开发及资源评价有重要意义。  相似文献   

High Resolution ID-TIMS Redefines the Distribution and Age of the Main Mesozoic Lacustrine Hydrocarbon Source Rocks in the Ordos Basin,China     

CUI Jingwei  ZHU Rukai  ZHANG Zhongyi  Jahandar RAMEZANI  LI Yang 《《地质学报》英文版》2023,97(2):581-588

Using high-precision zircon U-Pb ID-TIMS geochronology, tuffs from the Chang 9 shale and the Chang 7 shale were dated. The tuff in the Chang 9 shale is 241.47 ± 0.17 Ma, which falls between the top tuff age of 241.06 ± 0.12 Ma and the bottom tuff age of 241.558 ± 0.093 Ma in the Chang 7 shale. These reveal that the Chang 9 and Chang 7 shales are contemporaneous, belonging to the Ladinian stage of the Middle Triassic. This insight expands the region of the main source rock of Chang 7 to the north...  相似文献