地质样品扫描质子探针元素分布图的本底值剔除研究

建立了一个简便、可靠的扫描质子探针元素分布图本底值剔除方法，编制了逐点本底计数值剔除计算程序。结合实际地质样品的扫描质子探针元素分布成图，对方法的有效性做了对比实验。结果表明，与传统的成图方法相比，新方法具有图像清晰、真实的优点。同时讨论了方法的误差和误差的减小途径。     

Nonlinear regression for dependent variables

Nonlinear regression methods can be used to fit functions for two related variables where both variables are subject to error. A computer program for nonlinear estimation described previously has been modified to fit such functions for a given set of data. A numerical example is provided for a second-degree equation in xand y.A closer fit to an observed set of data is possible if the error structure for the variables is specified.     

Land surface in gravity points classification by a complete system of curvatures

A general theory of land surface in a gravitational field is being developed. The four classes of topographic variables are defined: local (class A) and global (class B) that have no sense without gravity, and local (class C) and global (class D) which are gravity invariant. A complete system of curvatures is introduced for a general situation of nonuniform gravity. The curvatures refer to classes A and C, the latter being subject of the differential geometry of surfaces, the former being subject of this work in a special section of mathematics concerned with surfaces in a vector field. The svstem of curvatures consists of 7 known ones of the classes A and C and 5 new curvatures of the class A (difference, horizontal excess, vertical excess, total ring, and total accumulation curvatures). Seven new theorems show in which way curvatures can reflect landforms and their ability to influence substance flows, and the relationship between them. Land surface in gravity-points classification is constructed based on signs of curvatures, which includes known curvature-based classifications as partial situations, and 12 main types (from total 48) are shown to form open subsets of the surface with equal probability to meet them for the land surface as indicated by a new statistical hypothesis. A central-point method for local variables calculation in uniform gravity approximation is described for a computer Digital Elevation Models treatment.     

What about managerial geography?

A business school perspective to Corporate Geography is offered. The mission is to provide an executive with operational tools for the creation of wealth. A search for the tools is better initiated with manufacturers and retailers. Individuality among corporations and markets makes deductive theories hazardous, a fact shown by examples from IKEA, Scania and Volvo Truck. Case studies, classified by a competitive situation, are seen as a more practicable alternative. From a large number of cases typical patterns can be derived. Anomalies indicate substandard or outstanding behavior. Their explanation contributes to the executive tool set. A unified approach of the currently scattered pieces is propagated.     

长短桩组合型复合地基优化设计方法研究

在软土地基上建造建(构)筑物需要进行地基处理,复合地基是一种行之有效的地基处理方式。工程上一般对地基浅层土的承载力要求较高,而深层只需满足下卧层强度要求即可。长短桩复合地基可做到浅层置换率高,深部置换率低,这样就合理地满足了软弱地基不同深度对承载力的要求。同时长短桩复合地基浅部置换率高,加固区复合地基模量大,深部置换率低,复合地基模量较低,正好适应浅部附加应力大,深部附加应力小的应力场,这样对减少软弱地基总沉降有利。本文探讨了长短桩复合地基优化设计方法,提出了长短桩复合地基优化设计数学模型,并利用复合形法求解优化设计数学模型,同时给出了优化设计计算算例,计算结果表明,此优化设计方法不仅可有效地保证长短桩复合地基设计方案技术上可靠,还可获得最佳的经济效益。     

北疆牧区MODIS积雪产品MOD10A1和MOD10A2的精度分析与评价

以北疆为研究区,结合气象台站记录的雪情数据,利用地理信息系统方法分析了2004年12月1日至2005年2月28日期间北疆地区90个时相的MODIS每日积雪产品MOD10A1和8日合成产品MOD10A2的积雪分类精度.研究表明:1)当积雪深度≤3 cm时,MOD10A1对积雪的识别率非常低,仅为7.5%;积雪深度为4~6 cm时,积雪识别率达到29.3%;积雪深度为15~20 cm,平均积雪识别率达到45.6%.当积雪深度>20 cm时,平均积雪识别率为32.2%;2)MOD10A1产品的积雪分类精度受天气状况的严重影响.在晴空状况下,该产品的最大积雪识别率达到58.2%;但是在多云或阴天时,平均积雪识别率仅为17.8%;3)下垫面对MOD10A1的分类结果也会造成影响,在荒漠区MOD10A1的积雪识别率为39.8%,在草原和稀树草原区的积雪识别率为37.2%,农业用地的积雪识别率最低,为29.1%;4)MOD10A2产品可较好的消除云层对地表积雪分类精度的影响,平均积雪识别率达87.5%,可较好的反映地表积雪的分布状况.     

A new ammonite faunal horizon in the Ovale Zone (Middle Jurassic,Lower Bajocian) and observations on the ammonite genus Sonninia at Coombe Quarry,Mapperton, near Beaminster,Dorset

Biostratigraphy is presented for horizons in the Discites to Sauzei zones at Coombe Quarry and Top Field at Mapperton, Dorset. The significance of these horizons is highlighted. Part of a chronocline is described in the Sonniniidae of the Discites Zone. A new ammonite faunal horizon, Docidoceras higginsi sp. nov. is erected as the oldest of the Ovale Zone. A revised subdivision of the zone is presented and the implications for the taxonomy and biogeography of the Stephanoceratidae is discussed. The distribution of Docidoceras may imply entry to western Tethys via a Hispanic Corridor. A method is presented for the allocation of generic names constituting segments of lineages.     

Mechanism and numerical simulation of reservoir slope deformation during impounding of high arch dams based on nonlinear FEM

The mechanism of reservoir slope deformation during impounding still lacks a convincing explanation. A generalized effective stress principle for rock masses is presented. A nonlinear iteration algorithm has been proposed and implemented in a 3D FEM program, TFINE. A case study of the Jinping-I high arch dam is then presented, and the calculated values of reservoir slope deformation agree well with the measured values. The results show that the change of the yield surface for the reservoir slope induced by adopting the effective stress principle results in plastic deformation, which is the main reason for slope deformation during impoundment.     

Application of the threshold method to air quality data

A new threshold method is explained in a manner suitable for workers in the general scientific area. Its application to the prediction of extreme pollutant concentrations is described and the results are compared with those of a conventional procedure, using a set of published data. A discussion concerning the difficulties of the presently used statistical technique is also included.     

Rapid evaluation of the critical slip surface in slope stability problems

Existing approaches for locating the critical slip surfaces are briefly reviewed. A number of techniques and strategies are proposed whereby the efficiency and robustness of some of the existing approaches can be enhanced. A new solution scheme is also developed for rapid calculation of the factor of safety. The new solution scheme requires only one level of iterations in contrast to the conventional solution scheme which invoives two levels of iterations. It is also applicable to a variety of stability models. A new compound iterative procedure is developed whereby the factor of safety can be calculated to a high accuracy within a few iterations. This reduces greatly the total computer time required for locating the critical slip surfaces.     

Settlement of a soil stratum subjected to an earthquake

A settlement analysis of a cohesionless soil layer subjected to an earthquake is presented. A theoretical solution utilizing Bessel functions and based on the so-called densification model for amplitudes has been obtained. This permits to calculate the settlement under cyclic loading. The simplified formula is also presented which allows for the fast and straightforward estimation of settlement. A numerical example is included giving the comparison of results obtained by different methods.     

Constitutive and numerical framework for modeling joints and faults in rock

A three‐dimensional constitutive model for joints is described that incorporates nonlinear elasticity based on volumetric elastic strain, and plasticity for both compaction and shear with emphasis on compaction. The formulation is general in the sense that alternative specific functional forms and evolution equations can be easily incorporated. A corresponding numerical structure based on finite elements is provided so that a joint width can vary from a fraction of an element size to a width that occupies several elements. The latter case is particularly appropriate for modeling a fault, which is considered simply to be a joint with large width. For small joint widths, the requisite equilibrium and kinematic requirements within an element are satisfied numerically. The result is that if the constitutive equation for either the joint or the rock is changed, the numerical framework remains unchanged. A unique aspect of the general formulation is the capability to handle either pre‐existing gaps or the formation of gaps. Representative stress–strain plots are given to illustrate both the features of the model and the effects of changes in values of material parameters. Copyright © 2015 John Wiley & Sons, Ltd.     

Définition de la perméabilité équivalente des massifs fracturés par des méthodes d'homogénéisationDefinition of the permeability of fractured rock masses by homogenisation methods

In the methods used for determination of the hydraulic behaviour at large scale of fractured rock masses, based on the simulation of flow in a fracture network, the mean flux and the mean pressure gradient in the network are not rigorously determined. A method is given for deriving these quantities, in a heterogeneous permeable block, from pressure and flux values on the boundary of the block. A block conductivity tensor is then defined, based on the condition of linear variation of the pressure on the boundary of the block. It is shown that this conductivity tensor is symmetric and positive-definite. An example of application to a model of fractured medium is given. To cite this article: A. Pouya, A. Courtois, C. R. Geoscience 334 (2002) 975–979.     

岩石统计渗流模型和统计损伤本构模型研究

采用Eshelby等效夹杂方法建立考虑渗流的岩石损伤本构模型是一种有效方法,但相关文献目前还极少。利用细观力学的Eshelby等效夹杂方法, 探索了考虑渗流和损伤的Helmholtz自由比能函数的确定,用连续介质损伤力学方法建立了相应的考虑渗流的岩石损伤统计本构模型,提出了考虑渗流和损伤过程的岩石破坏准则,建议了考虑损伤和应变的岩石渗透系数演化方程。与试验结果比较表明,所建立模型是合理的。     

A fast numerical method for evaluating the performance of float-sink coal-cleaning equipment

A method is presented which seeks to overcome a number of disadvantages that are inherent in the conventional practice of plotting the Tromp curve and analysing it for its various measures, e.g., specific gravity of separation, probable error and error area. A sufficient condition is established for extracting the appropriate criteria of the sharpness of classification, which are independent of coal-feed distribution in specific gravity. Partition area, a modified areal measure, similar to the conventional error area, of the equipment's deviation from ideal classification behavior is derived from the theoretical partition function. A purely numerical procedure is developed for locating the specific gravity of separation and the partition area. Unlike the Tromp-curve-based conventional procedure, the proposed histogram-based method is fast, more convenient and objective for analysing the coal-cleaning plant data.     

A generalized constitutive relation for a randomly packed particle assembly

A generalized stress-strain relationship is derived for a randomly packed particle assembly taking into account the effect of particle rotation. A second-order polynomial function is assumed for the field of particle displacement. From the principle of virtual work, stress measures for a granular solid are expressed in terms of contact forces, contact moments, and geometric measures for the particle structure. An explicit stress-strain relationship is derived for isotropic packing with equal-sized particles. Examples of a representative element under torsion and bending are given to demonstrate the applicability of the presently derived higher-order stress-strain relationship.     

A counterfort versus a cantilever retaining wall—a seismic equivalence

A procedure is presented to develop geometric dimensions and material property values for a model cantilever wall from those of a prototype counterfort wall such that the model wall will simulate the response of the prototype wall for seismic loads. The equivalency criteria are given. A sample problem is included to illustrate the use of the proposed procedure. Accuracy of results is discussed. Published in 2005 by John Wiley & Sons, Ltd.     

Analysis of rib supports for circular tunnels in elastic ground

Summary The response of circumferential ribs used to support a long circular tunnel in elastic ground is investigated. A rib-ground interaction solution is described for biaxial field stresses. A simplified procedure is also developed for predicting thrust and moment in rib supports.     

The orientation of bedding,veins and joints in core — a new method and case history

Summary A new technique is described for the orientation of bedding, joints and veins in diamond drill core taken from rocks in which a cleavage is developed. The geological and mathematical basis of the method is explained and a computer program suitable for IBM compatible microcomputers is included. A case history of its use during a gold exploration program at the Dolaucothi gold mines (Ogofau) in Dyfed, Wales is also presented which highlights its use in structural modelling and interpretation, geotechnical studies and in ore deposit geology.     

浅水湖泊平面二维水流-水质-底泥污染模型研究

从三维对流-扩散方程出发,推导包含底泥污染的水质控制方程,并与浅水流动方程耦合,建立相应的浅水湖泊平面二维水流-水质-底泥污染的数学模型。运用伽辽金加权余量法推导出数学模型方程组的有限元公式,开发了实时二维水动力、水质模型。利用模型计算玄武湖混合流、水质动态变化过程,结果与实测值较吻合,从而为浅水湖泊混合流、包含底泥污染的水质模拟提供了一种可操作的新途径。