XXIst International Congress of Photogrammetry and Remote Sensing     

Paul R. T.  Newby  Paul  Aplin  Simon J.  Buckley  Jim H.  Chandler  Jane E.  Drummond  David A.  Holland  Samantha J.  Lavender  Pauline E.  Miller  Jon P.  Mills  Henny  Mills  A. Stewart Walker  Peter A.  Woodsford 《The Photogrammetric Record》2009,24(125):66-102

The XXIst International Congress of Photogrammetry and Remote Sensing was held at the Beijing International Convention Centre, China, from 3rd to 11th July 2008. Reports are given on the Congress as a whole, including the General Assembly, some Technical Commission activities and the Congress Exhibition. Papers from the Congress are published in Volume XXXVII of the International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences.  相似文献   

准噶尔盆地新生代构造应力对石炭纪火山岩构造裂缝发育的控制   总被引：2，自引：1，他引：1  

肖芳锋  侯贵廷  李江海 《岩石学报》2010,26(1):255-262

构造裂缝的发育对改善储层的储渗条件有着重要的作用,特别是火山岩这种非传统储层,构造裂缝的发育是其成为有效储层的必要条件。本文主要借助构造应力场有限元数值模拟这一成熟的方法对准噶尔盆地石炭纪火山岩构造裂缝的发育状况进行预测。其两个主要的步骤是首先对区域构造应力场进行模拟计算,然后结合岩石的强度指标判断构造裂缝的发育状况。通过对准噶尔盆地地质背景和构造演化的分析,明确了新生代构造应力场的的决定性作用和石炭纪火山岩的分布区域(划分出六个区域),建立了数值模拟的计算模型、确定了边界条件与载荷。通过二维有限元数值模拟(应用Ansys软件)得到了新生代盆地应力场的分布特征和应力值。结合岩石强度指标,对火山岩构造裂缝(张裂缝和剪裂缝)的发育进行了预测并圈出相应的区域,主要为盆地西北缘、中央坳陷中部、滴西1东部,彩参2周缘、大井-将军庙等地区,对石炭纪火山岩的油气勘探战略选区, 优化勘探部署具有重要指导意义。  相似文献   

Developing elasto‐plastic models without establishing any expression for the yield function     

C. M. Sands  H. W. Chandler  I. A. Guz 《国际地质力学数值与分析法杂志》2011,35(8):932-946

This paper presents a procedure for developing elasto‐plastic material models from a dissipation function and kinematic constraint that obviates the need to establish an expression for the yield function. This method could be applied to a wide range of different materials, but it is particularly suitable for testing new models of granular materials. This is because there is often a difficulty associated with finding an algebraic expression for the yield function for appropriate dissipation functions combined with realistic dilatancy rules. The procedure presented in this paper allows the approach to fulfill its potential for the easy incorporation of physical insight into the dissipation function and kinematic constraint without being hindered by algebraic complexity. The method is applied to the familiar von Mises model and also to a model for granular materials that incorporates a realistic dilatancy rule and extends into three dimensions a model presented in earlier work. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Distribution of surface imperviousness in small urban catchments predicts runoff peak flows and stream flashiness          下载免费PDF全文

Babak K. Roodsari  David G. Chandler 《水文研究》2017,31(17):2990-3002

Urban growth is a global phenomenon, and the associated impacts on hydrology from land development are expected to increase, especially in peri‐urban catchments. It is well understood that greater peak flows and higher stream flashiness are associated with increased surface imperviousness and storm location. However, the effect of the distribution of impervious areas on runoff peak flow response and stream flashiness of peri‐urban catchments has not been well studied. In this study, a new geometric index, Relative Nearness of Imperviousness to the Catchment Outlet (RNICO), is defined to correlate imperviousness distribution of peri‐urban catchments with runoff peak flows and stream flashiness. Study sites include 21 suburban catchments in New York representing a range of drainage area from 5 to 189 km² and average imperviousness from 10% to 48%. On the basis of RNICO, all development patterns are divided into 3 classes: upstream, centralized, and downstream. Results showed an obvious increase in runoff peak flows and decrease in time to peak when moving from upstream to centralized and downstream urbanization classes. This indicates that RNICO is an effective tool for classifying urban development patterns and for macroscale understanding of the hydrologic behavior of small peri‐urban catchments, despite the complexity of urban drainage systems. We also found that the impact of impervious distribution on runoff peak flows and stream flashiness decreases with catchment scale. For small catchments (A < 40 km²), RNICO was strongly correlated with the average (R² = .95) and maximum (R² = .91) gaged peak flows due to the relatively efficient subsurface routing through stormwater and sewer networks. Furthermore, the Richards–Baker stream flashiness index in small catchments was positively correlated with fractional impervious area (R² = .84) and RNICO (R² = .87). For large catchments (A > 40 km²), the impact of impervious surface distribution on peak flows and stream flashiness was negligible due to the complex drainage network and great variability in travel times. This study emphasizes the need for greater monitoring of discharge in small peri‐urban catchments to support flood prediction at the local scale.  相似文献   

Variability of interrill erosion at low slopes   总被引：2，自引：0，他引：2  

A. Armstrong  J. N. Quinton  B. C. P. Heng  J. H. Chandler 《地球表面变化过程与地形》2011,36(1):97-106

Numerous models and risk assessments have been developed in order to estimate soil erosion from agricultural land, with some including estimates of nutrient and contaminant transfer. Many of these models have a slope term as a control over particle transfer, with increased transfer associated with increased slopes. This is based on data collected over a wide range of slopes and using relatively small soil flumes and physical principals, i.e. the role of gravity in splash transport and flow. This study uses laboratory rainfall simulation on a large soil flume to investigate interrill soil erosion of a silt loam under a rainfall intensity of 47 mm h^?1 on 3%, 6% and 9% slopes, which are representative of agricultural land in much of northwest Europe. The results show: (1) wide variation in runoff and sediment concentration data from replicate experiments, which indicates the complexities in interrill soil erosion processes; and (2) that at low slopes processes related to surface area connectivity, soil saturation, flow patterns and water depth may dominant over those related to gravity. Consequently, this questions the use of risk assessments and soil erosion models with a dominant slope term when assessing soil erosion from agricultural land at low slopes. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

5-GHz MERLIN and VLBA observations of compact 9C sources     

R. C. Bolton  C. J. Chandler  G. Cotter  T. J. Pearson  G. G. Pooley  A. C. S. Readhead  J. M. Riley  E. M. Waldram 《Monthly notices of the Royal Astronomical Society》2006,367(1):323-330

In this paper, we present subarcsecond resolution observations of 36 compact sources from the 15^h region of the 15-GHz 9th Cambridge survey. These sources all have previously measured simultaneous continuum radio spectra spanning 1.4–43 GHz and we classify each source by fitting a quadratic function to its spectrum. Using the Multi-Element Radio-Linked Interferometer Network and the Very Long Baseline Array, both at 5 GHz, we resolve all six steep-spectrum objects and four of the 13 flat-spectrum objects. However, none of the 16 objects with convex spectra peaking above 2.5 GHz is resolved even at <3-mas resolution. These results, in combination with the findings of a 15-GHz variability study, suggest that emission from the high-frequency peaking objects is affected by relativistic beaming, and that these objects are not necessarily as young as the synchrotron self-absorption interpretation of their peak frequencies would imply.  相似文献   

Including friction in the mathematics of classical plasticity     

H. W. Chandler  C. M. Sands 《国际地质力学数值与分析法杂志》2010,34(1):53-72

In classical plasticity there are clear mathematical links between the dissipation function and the consequent yield function and flow rule. These links help to construct constitutive equations with the minimum of adjustable parameters. Modelling granular materials, however, requires that the dissipation function depends on the current stress state (frictional plasticity) and this changes the mathematical structure—altering the links and invalidating the associated flow rule. In this paper we show, for a large family of dissipation functions, how much of the structure remains intact when frictional dissipation is included. The surviving links are examined using straightforward physically based graphical insight and well‐established mathematical techniques leading to a central result, which provides a mathematical justification for the procedural features of hyperplasticity. This should allow hyperplasticity to be used more widely and certainly with increased confidence. As an example of the effectiveness of the general method, two specific dissipation functions are constructed from the simple physical concepts of sliding friction and granule damage. One is based on a Drucker–Prager cone and the other a Matsuoka–Nakai cone, both incorporate kinematic hardening and a compactive cap. In each Case a single smooth yield function with consistent flow rules is produced. The computational usefulness of an inequality derived in the paper is demonstrated in the generation of the figures showing yield surfaces and flow directions by means of a simple maximization procedure. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Soil moisture states,lateral flow,and streamflow generation in a semi‐arid,snowmelt‐driven catchment     

James P. McNamara  David Chandler  Mark Seyfried  Shiva Achet 《水文研究》2005,19(20):4023-4038

Hydraulic connectivity on hillslopes and the existence of preferred soil moisture states in a catchment have important controls on runoff generation. In this study we investigate the relationships between soil moisture patterns, lateral hillslope flow, and streamflow generation in a semi‐arid, snowmelt‐driven catchment. We identify five soil moisture conditions that occur during a year and present a conceptual model based on field studies and computer simulations of how streamflow is generated with respect to the soil moisture conditions. The five soil moisture conditions are (1) a summer dry period, (2) a transitional fall wetting period, (3) a winter wet, low‐flux period, (4) a spring wet, high‐flux period, and (5) a transitional late‐spring drying period. Transitions between the periods are driven by changes in the water balance between rain, snow, snowmelt and evapotranspiration. Low rates of water input to the soil during the winter allow dry soil regions to persist at the soil–bedrock interface, which act as barriers to lateral flow. Once the dry‐soil flow barriers are wetted, whole‐slope hydraulic connectivity is established, lateral flow can occur, and upland soils are in direct connection with the near‐stream soil moisture. This whole‐slope connectivity can alter near‐stream hydraulics and modify the delivery of water, pressure, and solutes to the stream. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

A review of reference models for assessing inelastic seismic torsional effects in buildings     

J. C. Correnza  G. L. Hutchinson

A. M. Chandler 《Soil Dynamics and Earthquake Engineering》1992,11(8):465-484

This paper reviews the various forms of reference model adopted for studies that evaluate inelastic seismic torsional effects and assess their implications for building design. Both qualitative and quantitative comparisons are presented. The importance of selecting an appropriate reference model is in accordance with the above aims is emphasised. It is found that variations in the reference models adopted in analyses of inelastic seismic torsional effects may lead to significant differences in the results obtained and, hence, to the conclusions drawn from such studies. It is demonstrated that accidental torsional effects, as incorporated in code design provisions, result in significant changes to the distribution of element strengths and the inelastic response behaviour of symmetric and generalised torsionally balanced reference models. Such changes should be considered when employing such models to evaluate the ineslatic response of torsionally unbalanced building systems.  相似文献   

Radar detection of near-Earth Asteroids 1915 Quetzalcoatl, 3199 Nefertiti, 3757 (1982 XB), and 4034 (1986 PA)     

Michael K. Shepard  Lance A.M. Benner  Donald B. Campbell  John F. Chandler 《Icarus》2004,172(1):170-178

We describe Arecibo (2380 MHz, 12.6 cm) Doppler-only radar detections of near-Earth Asteroids 1915 Quetzalcoatl, 3199 Nefertiti, 3757 (1982 XB), and 4034 (1986 PA) obtained between 1981 and 1989. Estimates of the echo spectral bandwidths, radar cross-sections, and circular polarization ratios of these objects constrain their sizes, radar albedos, surface roughnesses, taxonomic classes, rotation periods, and pole directions. Our radar constraints on the diameters of Quetzalcoatl and Nefertiti are most consistent with sizes determined using thermal-radiometry and the Fast Rotation Model (FRM); this consistency may indicate that these asteroids have surfaces of high thermal inertia (i.e., little or no regolith). Constraints on Quetzalcoatl's radar albedo rule out a “metallic M” classification. The radar constraints for Nefertiti are inconsistent with a rotation pole published by Kaasalainen et al. (2004, Icarus 167, 178). Our estimates of 1982 XB's size are consistent with previously published estimates. The radar bandwidth of 1986 PA places an upper bound of about 24 h on its rotation period.  相似文献