Elliptical motion of a star in a close binary system

The motion of a rotating star in a close binary system with conservative mass exchange is considered. In contrast to the Paczyński-Huang model, the new model applied examines the relative motion of a star along an elliptical orbit in a close binary system, taking into account the mutual gravitation between the stars, reactive forces, the gravitation exered on the stars by the mass-transfer stream, and perturbations due to the rotation of the accreting star. The variations of the semi-major axis and eccentricity of the orbit and the orbital angular velocity of the accreting star as a function of the component-mass ratio q are determined. The results are applied to the BF Aurigae system.     

Low energy trajectories for the Moon-to-Earth space flight

The Moon-to-Earth low energy trajectories of ‘detour’ type are found and studied within the frame of the Moon-Earth-Sun-particle system. These trajectories use a passive flight to the Earth from an initial elliptic selenocentric orbit with a high aposelenium. The Earth perturbation increases the particle selenocentric energy from a negative value first to zero and then to a positive one and therefore leads to a passive escape of the particle motion from the Moon attraction near the translunar libration pointL ₂. This results in the particle flight to a distance of about 1.5 million km from the Earth where the Sun gravitation decreases the particle orbit perigee distance to a small value that leads to the particle approaching the Earth vicinity in about 100 days of the flight. A set of the Moon-to-Earth ‘detour’ trajectories is defined numerically. Characteristics of these trajectories are presented. The ‘detour’ trajectories give essential economy of energy (about 150 m/s in Delta V) relative to the usual ones.     

Rotational-oscillatory variations in the Earth rotation parameters within short time intervals

A mathematical model for rotational-oscillatory motions of the Earth is constructed by applying celestial mechanics to the spatial problem of the Earth-Moon system subject to the Sun’s gravitation. Some basic phenomena associated with tidal irregularity in the Earth’s axial rotation and the polar oscillations are studied. It is shown that the perturbing component of the gravitational-tidal forces orthogonal to the plane of the lunar orbit is responsible for some short-term perturbations in the Moon’s motion. The constructed model for the rotational-oscillatory motions of the deformable Earth includes both the main high-amplitude perturbations and more complex small-scale motions attributed to short-term lunar perturbations with combinational frequencies. Numerical modeling (interpolation and forecasting) of the Earth rotation parameters within various time intervals based on astrometric data obtained by the International Earth Rotation Service is presented.     

Coupling of finite and hierarchical infinite elements: application to a non‐homogeneous cross‐anisotropic half‐space subjected to a non‐uniform circular loading

A method is presented for coupling cubic‐order quadrilateral finite elements with the finite side of a new coordinate ascent hierarchical infinite element. At a common side shared by a hierarchical infinite element and an arbitrary number of finite elements, the displacements are minimized in the least square sense with respect to the degrees‐of‐freedom of the finite elements. This leads to a set of equations that relate the degrees‐of‐freedom of the finite and hierarchical infinite elements on the shared side. The method is applied to a non‐homogeneous cross‐anisotropic half‐space subjected to a non‐uniform circular loading with Young's and shear moduli varying with depth according to the power law. A constant mesh constructed from coupled finite and hierarchical infinite elements is used and convergence is sought simply by increasing the degree of the interpolating polynomial. The displacements and stresses produced by conical and parabolic circular loads applied on the surface are obtained. The efficiency of the proposed method is demonstrated through convergence and comparison studies. New results produced by a frusto‐conical circular load applied on the surface of a half‐space made up of heavily consolidated London clay are provided. The non‐homogeneity parameter and degree of anisotropy are shown to influence the soil response. Copyright © 2012 John Wiley & Sons, Ltd.     

基于GIS遥感区域构造的空间信息集成研究

主要论述在综合信息矿产预测中基于GIS的遥感资料自动解译原理和实现方法，通过对遥感资料的数据处理并结合已建立的重磁构造格架，进行空间信息的自动关联识别，提取有地质意义的遥感线性、环形构造。探讨了实现遥感空间信息自动集成技术和其在遥感图像中的具体应用。     

A multidimensional analysis and the chronologic structure of the Earth’s geodynamic activity

An attempt has been undertaken to examine time series of volcanic and seismic events in a multidimensional reference system related to the parameters of the Earth’s orbital motion. Volcanic eruptions and strong (M > 5) earthquakes (a sample from the USGS/NEIC seismological database: Significant Worldwide Earthquakes) [18] were analyzed within the fields of the JPL Planetary and Lunar Ephemerides, (DE-406) astronomical indicators [19]: the Earth-Moon distance, Earth-Sun distance, ecliptic latitude of the Moon, and the differences between the geocentric longitudes of the Moon and Sun, Venus and Sun, and Mars and Sun. Distribution spectra were obtained and normalization was performed taking the nonuniform motion of celestial bodies into consideration, and the values of multidimensional diurnal probability were calculated. As a result, the statistically reliable drift in the distribution of geoevents was calculated relative to the duration of the intervals of multidimensional diurnal probability, which indicates distribution regions where more geoevents can take place during shorter intervals (and vice versa). Linear relationships between the multidimensional diurnal probability and diurnal probability of geoevents were found. All these results and the astronomic ephemerides were used as a base for computing the probabilities of volcanic and seismic activity of the Earth for the period of 2005–2007. The spatial structure of volcanic and seismic processes was examined, which allowed the revelation of probabilistic parameters of the spatiotemporal structure of Earth’s geodynamic activity and outlining an approximate algorithm for its monitoring.     

渣渡矿区滑脱构造特征

渣渡矿区滑脱构造比较发育,既有推覆构造,也有滑覆构造;有顺层,也有切层;并具有多期次及先推后滑等特点。由于燕山晚期岩浆岩的侵入及锡矿山背斜的形成,在背斜两翼产生重力滑动构造。其前缘挤压区均追踪利用了金盘仑断层和集云断层的南段,使本区南部构造复杂化,而北部构造仍保持较简单的格局,因而造成了本区南北构造分异的现象。      

A simple model for the prediction of the deflation threshold shear velocity of dry loose particles

A very important parameter in aeolian equations is the deflation threshold shear velocity, which quantifies the instant of particle motion. In this paper, a simple model is presented for the prediction of the threshold shear velocity of dry loose particles. It has the same functional form as the widely used models of Bagnold (1941) and Greeley & Iversen (1985), but differs in its treatment of the so‐called threshold parameter. As the new expression was based on the moment balance equation used by Greeley & Iversen, it includes a function for the aerodynamic forces, including the drag force, the lift force and the aerodynamic moment force, and a function for the interparticle forces. The effect of gravitation is incorporated in both functions. However, rather than using an implicit function for the effect of the aerodynamic forces as in the Greeley & Iversen model, a constant aerodynamic coefficient was introduced. From consideration of the van der Waals' force between two particles, it was also shown that the function for the interparticle cohesion force is inversely proportional to the particle diameter squared. The model was calibrated on data reported by Iversen & White (1982). The new expression compared, at least for terrestrial conditions, very well with the Greeley & Iversen model, although it is much simpler. It was finally validated with data from wind‐tunnel experiments on different fractions of dune sand and sandy loam soil aggregates. The soil aggregates were treated as individual particles with a density equal to their bulk density. The good agreement between observations and predictions means that, when predicting mass transport of particles above a given soil, minimally dispersed particle‐size distributions should be considered rather than the granulometric composition of the soil.     

时间域航空电磁数据线圈运动噪声去除方法仿真研究

时间域航空电磁探测中,接收线圈在地磁场中的运动产生感应电动势,形成线圈运动噪声,因其幅度较大而成为航空电磁探测中的主要噪声源之一。线圈运动噪声具有低频特性,虽然幅度随频率增大而迅速衰减,但仍然含有高于发射基频的频率成分;因此,传统的高通滤波器在处理线圈运动噪声中存在一定的局限性。根据航空电磁数据的特点,采用多项式拟合全波半周期运动噪声,运用拉格朗日优化算法求解运动噪声多项式系数,并将其从半周期电磁数据中去掉以达到去除噪声的目的。通过仿真实测数据的运动噪声压制实验,对比分析了多项式拟合法与传统高通滤波器法的线圈运动噪声去除能力。仿真结果表明,多项式拟合法能够有效去除航空电磁数据中的线圈运动噪声,提高信噪比超过40 dB。     

Adaptive analysis of infinite beams dynamics problems using the periodic configuration update method in the time domain

This paper proposes a new approach for the assessment of the dynamic response of continuously supported infinite beams under high‐speed moving loads. A change in the representation of equations of motion in the dynamics of discrete structures is proposed to obtain an improved accuracy of the numerical integration in the time domain. The proposed numerical method called the “periodic configuration update” or “PCU method” is applied to solve the problem of a vertical moving harmonic load on an infinite classical Euler‐Bernoulli beam resting on a continuous viscoelastic foundation. This study shows the superiority of the proposed method in comparison with other methods presented in the literature that suffer from the material time derivative, i.e., convective terms, that arises from the Galilean transformation. To confront this numerical problem, the PCU method retains the principle of the spatial follow of loads while zeroing the relative velocity with the traversed beam via a step‐by‐step adaptive integration of the equation of structural dynamics. The dynamic load is modeled with high theoretical velocities that can reach the critical velocity of the studied beam with different angular frequencies belonging to moderate frequency range. A parametric study is carried out to analyze the influence of key parameters on the convergence. The obtained results show a high efficiency of the PCU method for solving these types of problems relative to the dynamics of high speed trains/tracks.     

On facies belts and facies mosaics: Holocene isolated platforms,South China Sea

Although the general criteria for recognition and environmental interpretation of different carbonate facies are well‐established, a predictive understanding of the areal extent and spatial patterning of facies bodies and why they might organize into facies belts or facies mosaics is poorly constrained. To explore patterns and process dynamics of facies on isolated carbonate platforms, quantitative analysis of thematic maps derived from remote sensing images of 27 Holocene atolls of the Paracel and Spratly chains in the South China Sea explores variability within and among platforms. On these systems, most annular shelf‐margin reefs are less than 500 m wide on both chains; inboard of the reefs, reef sand aprons range up to 500 m (Spratlys) and 1000 m (Paracels) wide. Around individual platforms, Spratly Chain sand apron widths are wider to the north‐west, whereas apron widths in the Paracel Chain are more symmetrical; collectively, data indicate log‐normal width‐exceedance probability distributions. Platform‐interior patch reefs include area‐exceedance probability distributions and gap size distributions (lacunarity) consistent within chains, but distinct between the chains. To understand the processes underlying distinct distributions, simulations explored distinct growth scenarios. Results suggest that differences may represent distinct process classes: proportional growth processes with multiplicative random effects (reef sand aprons – belts), versus non‐linear, size‐proportional growth of randomly aged and distributed elements (patch reefs – mosaics). The probabilistically distinct sizes and spatial patterns of geomorphic elements within these general process classes are interpreted to represent ‘variations on themes’ related to the different impacts of tropical storms, winter cold fronts and circulation in each chain. The results highlight fundamentally different growth patterns impacting the sizes and distribution of facies belts and mosaics on isolated carbonate platforms. Because these types of bodies ultimately construct stratigraphy, the themes could be applied to understand and predict variability in the architecture of subsurface reservoir analogues.     

Isotopic fingerprints of Milankovitch cycles in Pennsylvanian carbonate platform‐top deposits: the Valdorria record,Northern Spain

Sedimentary cyclic sequences deposited during the Late Palaeozoic Ice Age are widespread. Glacio‐eustatic control of the cyclic patterns is commonly accepted, and the durations of the cyclothems generally match the short‐ and long‐eccentricity Milankovitch orbital parameters. Nevertheless, geochemical fingerprints of orbital parameters are poorly documented in deep‐time sedimentary records. Here, we report on well‐exposed Bashkirian cyclothems of c. 123 ka and c. 400 ka durations from the Valdorria platform. The shorter‐term cyclothems can be grouped into longer‐term composite sequences that are consistent with generally accepted durations of c. 125 ka and c. 400 ka for Milankovitch eccentricity cycles. The stratigraphic pattern is mirrored by the isotope geochemical signals, which show distinct recurring trends. These trends are confirmed by statistical tests. Whereas intrinsic factors and/or subaerial exposure related to sea‐level lowstands might have truncated cycle patterns in tectonically stable basins, rapid subsidence of the Valdorria platform's foreland basin appears to have contributed to a faithful recording of cyclothems of different orders. The patterns and biostratigraphic constraint revealed in this study demonstrate the power of orbital forcing in imprinting sedimentary and geochemical signals in the rock record.     

Mantle resistance against Gibraltar slab dragging as a key cause of the Messinian Salinity Crisis

The Messinian Salinity Crisis (5.97–5.33 Ma) was caused by the closure of the Atlantic‐Mediterranean gateways that cut through the Gibraltar orogenic system. The geodynamic drivers underlying gateway closure and re‐opening are still debated. Here, we interrogate the gateway successions to find the imprints of surface deformation, infer the timing and nature of associated geodynamic drivers, and test such inferences against numerical simulations of slab dynamics. We find that since the latest Miocene, a tectonic framework was established in the gateway region dominated simultaneously by (a) relative plate convergence, (b) slab tearing under the eastern Betic Cordillera and (c) mantle resistance against north‐northeastward dragging of the Gibraltar slab by the African plate's absolute motion. We propose that mantle‐resisted slab dragging and slab tearing operated in concert closing the gateways that caused the Messinian Salinity Crisis, whereas sinking of heavy oceanic lithosphere located between buoyant continental plates re‐opened the Strait of Gibraltar at 5.33 Ma.     

Astronomical Dating of the Middle Miocene Hanjiang Formation in the Pearl River Mouth Basin,South China Sea

The Hanjiang Formation of Langhian age(middle Miocene) in the Pearl River Mouth Basin (PRMB),South China Sea consists of deltaic siliciclastic and neritic shelf carbonate rhythmic alternations,which form one of the potential reservoirs of the basin.To improve stratigraphic resolutions for hydrocarbon prospecting and exploration in the basin,the present study undertakes spectral analysis of high-resolution natural gamma-ray(NCR) well-logging record to determine the dominant frequency components and test whether Milankovitch orbital signals are recorded in rhythmic successions.Analytical results indicate the orbital cycles of precession(～19 ka and～23 ka), obliquity(～41 ka),and eccentricity(～100 ka and～405 ka),which provide the strong evidence for astronomically driven climate changes in the rhythmic alternation successions.Within biochronological constraint,a high-resolution astronomical timescale was constructed through the astronomical tuning of the NGR record to recent astronomically calculated variation of Earth’s orbit. The astronomically tuned timescale can be applied to calculate astronomical ages for the geological events and bioevents recognized throughout the period.The first downhole occurrences of foraminifers Globorotalia peripheroronda and Globigerinoides sicanus are dated at 14.546 Ma and 14.919 Ma,respectively,which are slightly different from earlier estimates in the South China Sea. When compared with the global sea-level change chart,the astronomical estimate for the sequences recognized based on microfossil distributions have the same end time but the different initiation time. This is probably due to the local or regional tectonic activities superimposed on eustatic rise which postponed the effect of global sea-level rising.Astronomical timescale also resolves the depositional evolution history for the Langhian Stage(middle Miocene) with a variation that strongly resembles that of Earth’s orbital eccentricity predicted from 13.65 Ma to 15.97 Ma.We infer that the main factor controlling the variability of the sedimentation rate in the Hanjiang Formation is related to the～405-ka-period eccentricity.     

Characterizing Fracture Spatial Patterns by Using Semivariograms

Semivariogram is applied to fracture data obtained from detailed scanline surveys of nine field sites in western New York, USA in order to investigate the spatial patterns of natural fractures. The length of the scanline is up to 36 m. How both fracture spacing and fracture length vary with distance is determined through semivariogram calculations. In this study, the authors developed a FORTRAN program to resample the fracture data from the scanline survey. By calculating experimental semivariogram, the authors found five different types of spatial patterns that can be described by linear, spherical, reversed spherical, polynomial I (for a<0) and polynomial II (for a>0) models, of which the last three are newly proposed in this study. The well-structured semivariograms of fracture spacing and length indicate that both the location of the fractures and the length distribution within their structure domains are not random. The results of this study also suggest that semivariograms can provide useful infor     

基岩裂隙流水位与流程关系的统计研究

基于室内模拟试验及有关资料,研究了不同条件下基岩裂隙水一维流水位与流程的统计关系,并将结果与前人研究进行了比较分析,得出以下结论:a.基岩裂隙水无压流水位三次方与流程呈线性关系,承压流水头与流程呈线性关系;b.承压流条件下统计结果与前人研究结果无实质性差别,而对无压流,统计结果与孙峰根等人的研究结果一致,与传统的结果,即水位平方和流程呈线性关系不一致;c.统计结果对基岩裂隙水运动理论的研究与应用具有重要的参考价值      

Analytical solutions for a three‐invariant Cam clay model subjected to drained loading histories

Analytical solutions are derived for a three‐invariant Cam clay model subjected to proportional and circular drained loading histories. The solutions are presented for a specific volume, and volumetric and generalized shear strains. In the case of a proportional loading only straight effective stress paths are considered while in the case of a circular loading the maximum possible change in Lode's angle is π/3 due to plastic isotropy. Additionally, a concept of deviatoric stiffness is devised and an analytical expression for the generalized hardening modulus is derived. Qualitative and quantitative analyses are carried out in the form of direct comparisons between analytical solutions for drained and undrained loading histories thus offering an improved understanding of the three‐invariant model. Copyright © 2006 John Wiley & Sons, Ltd.     

中国玛珥湖及其研究意义

随着全球变化研究的深入,科学家们认识到古气候变化除轨道尺度的冰期/间冰期旋回之外还存在年代际-千年尺度的高频变化和突变事件。要认知这些变化,古气候记录的时间分辨率要达到"年-年代际"。因此,寻求时间跨度长、连续性好、信息丰富的高分辨率记录是过去全球变化研究面临的主要任务之一。玛珥湖为火山射汽喷发形成的封闭湖泊,由于其独特的形成机制及水文背景,使其能够提供数万年乃至几十万年连续稳定的沉积记录,是高分辨率古气候、古环境变化研究的重要对象。中国玛珥湖得天独厚,从热带到寒温带均有分布,为系统研究中国不同气候区各种时间尺度古气候变化规律提供了理想材料。本文基于中国玛珥湖的分布及沉积特征,探讨玛珥湖沉积记录能够为古全球变化研究做出怎样的贡献,解决什么科学问题,具体包括以下三个方面的内容:(1)在轨道尺度上,精确定位现代气候在地质历史中的位置是未来最具挑战性的科学问题之一。我国热带地区玛珥湖沉积物跨越了至少4个冰期-间冰期旋回,能够为理解冰期驱动机制、下一次冰期来临、高低纬关联等关键科学问题提供多学科数据;(2)千年尺度古气候变化,其成因可能源于不同的动力学机制,是气候系统对各种外部和内部驱动因子响应的结果,因此千年震荡可能存在明显的时空差异。集成不同气候带的玛珥湖沉积记录将为理解千年震荡规律及其驱动因子做出贡献;(3)年-年代际气候变化是预测未来气候变化的基础,PAGES、IPCC以及PAGES-Asia 2K均将过去2千年来气候变化作为预测未来几十年至百年尺度上重大全球变化的背景,并为此构建全球数据体系,玛珥湖沉积特别是纹层沉积记录能够填补某些地区高分辨率数据的空白。     

Kinematics and timing of continental block deformation from margins to interiors

During the deformation of continental blocks, the magnitude of tectonic stress generally decreases with increasing distance from the margin of the block. However, the timing and kinematics of stress transmission from the margins to the interiors of continents are poorly resolved, even though this information is critical to our understanding of the dynamics of continental deformation. Here, we present a case study of Mesozoic deformation of the North China Craton (NCC). Field investigations of Mesozoic thrust faults and folds, granitic intrusions and dykes, combined with zircon SHRIMP and LA–ICP–MS dating and muscovite ⁴⁰Ar/³⁹Ar plateau ages, reveal the age of the NE–SW‐trending tectonic belts as ~180–155 Ma, where the deformation of the craton margin occurred 10–20 Ma earlier than that of the craton's interior. Although the kinematics of deformation are similar for the interior and the margin of the NCC, strain decreases with increasing distance from the margin. Notably, the bulk of the strain in the cratonic interior was focused in zones of pre‐existing weakness. Overall, we determined that the NCC deformed under conditions of uniaxial compression, a conclusion that is compatible with simple rheological models, and that the stress magnitude attained in the cratonic interior was much less than that along its margin.