A method for determining the reversibility of a Markov sequence   总被引：1，自引：0，他引：1  

David Richman  W. E. Sharp 《Mathematical Geology》1990,22(7):749-761

This paper describes, given a tally matrix with strictly positive entries, a method to determine whether the associated Markov process is reversible, and (for reversible Markov processes) methods to compute the reversibility matrix from the tally matrix. If the tally matrixN is symmetric, then it is shown that the Markov process must be reversible and the reversibility matrixC equalss (R ^–1NR^–1), whereR is the diagonal matrix whosei ^th diagonal entry is the sum of the entries of thei ^th row ofN (for everyi) ands denotes the sum of all the entries ofN. Because a symmetric tally matrix is of special importance in applications, a ² test is proposed for determining, in the presence of experimental errors, whether such a matrix is symmetric.  相似文献   

Current methods for obtaining,logging and splitting marine sediment cores   总被引：1，自引：0，他引：1  

P. P. E. Weaver  P. J. Schultheiss 《Marine Geophysical Researches》1990,12(1-2):85-100

The main types of deep-sea sediment coring devices are described and their relative merits and drawbacks are discussed. These devices include box corers, gravity corers, piston corers, giant piston corers and vibrocorers. Recent utilisations of kevlar and polyester coring warps are also discussed, since these are the only warps capable of handling the large weights associated with the larger devices. Recent developments in wholecore logging, including P wave, density and magnetic susceptibility, are described as are methods of subcoring and core splitting to obtain the maximum amount of detail on the split surfaces. The wholecore logs together with a good colour photograph of the recently split sediment surface provide a lasting unambiguous record of the core.  相似文献   

单斜角闪石的X-射线粉晶法鉴定          下载免费PDF全文

宋仁奎  应育浦  李哲 《地质科学》1992,(4):394

 从140个已知成分的角闲石的晶胞参数作图,发现在β-v₀图上不同种属的角闪石有各自的分布区,克服了前人用β-d₁₀₀图难以喹定角闪石种属的困难。  相似文献   

华北地区8级大震的深部构造特征及地震成因的探讨c          下载免费PDF全文

张先  张先康  刘敏  赵丽 《地震学报》2003,25(2):136-142

在地震地质、航磁反演及人工地震测深工作的基础上，阐明了华北地区8级大震的3个深部构造特征，即地震发生在深部超壳断裂的上部，地震发生在强度较大的构造块体的边缘，震源区深部存在低速、低密及高导层构造．同时对地震成因进行了探讨，讨论了构造运动和壳内爆炸两种地震成因的可能．   相似文献   

218P₀测深法寻找基岩地下水实用研究          下载免费PDF全文

李惠恩  桑运秀  侯士德  王景荣  王东锋 《水科学进展》2003,14(2):213-217

阐明了一种新的找水方法——218P₀测深法。对其操作过程和根据实测曲线识别含水层、确定含水层数、分析富水性,以及计算含水层底板埋深的方法作了分析,并对有关机理作了初步探讨。  相似文献   

Model of Reflection Spectra of Rock Surface in 2π Space   总被引：5，自引：0，他引：5  

ZHAO Hongying ZHAO Hu  YAN Lei  ZHAO YunshengInstitute of Remote Sensing  GIS  Peking University  Beijing  Beijing Key Lab of Spatial Information Integration  Its Applications  Institute of RS  GIS  Peking University  Beijing Department of Geography  Northeast Normal University  Changchun  Jilin 《《地质学报》英文版》2004,78(3):843-847

This paper deals with reflection spectra and polarized reflection spectra of 20 sorts of rock in 2π space, and then creates a model of reflection spectra of rock surface in 2π space. We measured the change of reflection and polarized reflection spectra as altering the incidence angle, vertex angle, azimuth angle, band and polarization. The results show that influence of the incidence angle on spectral curves is very strong. And when the vertex angle is constant, the horizontal azimuth polarizes rock spectra, and distorts the circular spectrum to become elliptic. The polarization influences the reflection intensity of rock spectra, but has no evident influence on the characteristics of wave forms of rock in 2π space. Therefore, we can describe the whole reflection spectral characteristics, including polarization, of rock surface in 2π space by measuring and calculating the e and p values in several key directions.  相似文献   

A study of the modelling error in two operator splitting algorithms for porous media flow     

K. Brusdal  H.K. Dahle  K. Hvistendahl Karlsen  T. Mannseth 《Computational Geosciences》1998,2(1):23-36

Operator splitting methods are often used to solve convection–diffusion problems of convection dominated nature. However, it is well known that such methods can produce significant (splitting) errors in regions containing self sharpening fronts. To amend this shortcoming, corrected operator splitting methods have been developed. These approaches use the wave structure from the convection step to identify the splitting error. This error is then compensated for in the diffusion step. The main purpose of the present work is to illustrate the importance of the correction step in the context of an inverse problem. The inverse problem will consist of estimating the fractional flow function in a onedimensional saturation equation.  相似文献   

A statistical study of the upstream intermediate ion boundary in the Earth’s foreshock     

K. Meziane  C. d’Uston 《Annales Geophysicae》1998,16(2):125-133

A statistical investigation of the location of onset of intermediate and gyrating ion populations in the Earths foreshock is presented based on Fixed Voltage Analyzer data from ISEE 1. This study reveals the existence of a spatial boundary for intermediate and gyrating ion populations that coincides with the reported ULF wave boundary. This boundary position in the Earths foreshock depends strongly upon the magnetic cone angle _BX and appears well defined for relatively large cone angles, though not for small cone angles. As reported in a previous study of the ULF wave boundary, the position of the intermediate-gyrating ion boundary is not compatible with a fixed growth rate of the waves resulting from the interaction between a uniform beam and the ambient plasma. The present work examines the momentum associated with protons which travel along this boundary, and we show that the variation of the boundary position (or equivalently, the associated particle momentum) with the cone angle is related to classical acceleration mechanisms at the bow shock surface. The same functional behavior as a function of the cone angle is obtained for the momentum predicted by an acceleration model and for the particle momentum associated with the boundary. However, the model predicts systematically larger values of the momentum than the observation related values by a constant amount; we suggest that this difference may be due to some momentum exchange between the incident solar-wind population and the backstreaming particles through a wave-particle interaction resulting from a beam plasma instability.  相似文献   

Sediment and trace element depositional history from the Ajkwa River estuarine mangroves of Irian Jaya (West Papua), Indonesia     

Gregg J. Brunskill  Irena Zagorskis  John Pfitzner  Joanna Ellison 《Continental Shelf Research》2004,24(19):2535-2551

Radiotracer ²¹⁰Pb and contaminant copper were used to estimate sediment accumulation rates in 4 cores from the Ajkwa River estuary and mangrove tidal channels in western Irian Jaya. Mass accumulation rates (4.5–13 kg dry wt m⁻² yr⁻¹) were within the envelope of expectations for a region of high rainfall, great river catchment relief, and rapid tectonic uplift of mountains. Copper accumulation rates were enhanced 40 fold in surface sediments, compared to pre-1950 sections of the sediment cores. These recent sediments with enhanced copper concentrations come from Freeport Indonesia mine tailings over the last 27 years. Variations in sediment core profiles of Al, Fe, and organic carbon were small, indicating no great change in bulk sediment composition. Sulfur concentrations decline toward the sediment surface, suggesting a decline in rates of microbial sulfate reduction. Enhanced sediment copper concentrations will be a useful tracer of sediment dispersal from the Ajkwa River estuary along this coast.  相似文献   

The University of Durham Mark 6 Gamma Ray Telescope     

P. Armstrong  P. M. Chadwick  P. J. Cottle  J. E. Dickinson  M. R. Dickinson  N. A. Dipper  S. E. Hilton  W. Hogg  J. Holder  T. R. Kendall  T. J. L. McComb  C. M. Moore  K. J. Orford  S. M. Rayner  I. D. Roberts  M. D. Roberts  M. Robertshaw  S. E. Shaw  K. Tindale  S. P. Tummey  K. E. Turver 《Experimental Astronomy》1999,9(2):51-80

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