Significant results from several array of magnetometers deployed in India to probe deep geoelectrical structures of the crust
and the upper mantle are reviewed in this paper. Emphasis is on critical appraisal of earlier results so that the article
summarizes what has been done so far and what caution is to be taken on future work.
Two large-scale arrays over northwest and peninsular India during 1979–80, have been followed up with six more linear or two-dimensional
arrays over different parts of the country.
“Trans-Himalayan” conductor aligned along the strike of Aravalli range, delineated by arrays over northwest India, essentially
represents one of the major continental induction anomalies mapped by electromagnetic methods. Efforts for quantifying the
induction effects through numerical models are shown to be constrained due to the large inter-station spacing, lack of information
on the regional background conductivity distribution and the non-inclusion of the frequency dependence of induction effects.
A more comprehensive modelling, not biased by these factors, enables approximating the Trans-Himalayan conductor as an asymmetric
domal upwarp in the middle and lower crust located between Delhi-Hardwar ridge and Moradabad fault. Numerical modelling results
for southern peninsular, despite the constraints, indicate that the strong and complex induction pattern can be adequately
attributed to the combination of conductors connected with triple junction between Indo-Ceylon Graben, Comorin ridge and the
west coast rifting.
Induction features derived from the Valsad array, operated over basalt-covered region of western India, demarcate an enhanced
conducting zone beneath Plume-associated triple junction in the Gulf of Cambay, apart from characterizing the presently active
seismic zone as a resistive block. 相似文献
The behavior of a self-supported earth-retaining wall with stabilizing piles was investigated using a numerical study and field tests in urban excavations. Special attention is given to the reduction of lateral earth pressures acting on a retaining wall with stabilizing piles. Field tests at two sites were performed to verify the performance of the instrumented retaining wall with stabilizing piles. A number of 3D numerical analyses were carried out on the self-supported earth-retaining wall with stabilizing piles to assess the results stemming from wide variations of influencing parameters such as the soil condition, the pile spacing, the distance between the front pile and the rear pile, and the embedded depth. Based on the results of the parametric study, the maximum horizontal displacement and the maximum bending moment are significantly decreased when the retaining wall with stabilizing piles is used. In engineering practice, reducing the pile spacing and increasing the distance between the front pile and the rear pile can effectively improve the stability of the self-supported earth-retaining wall with stabilizing piles. 相似文献
Large-scale land acquisitions (LSLAs) have become a major concern for land use sustainability at a global scale. A considerable body of case studies has shown that the livelihood outcomes of LSLAs vary, but the understanding of factors and processes that generate these livelihood outcomes remains controversial and fragmented in terms of cases, contexts, and normative orientations. Therefore, this study presents a meta-analysis of case studies and applies the archetypes approach developed in global change research to analyse the configurations of factors and processes that generate different livelihood outcomes in LSLA situations. The analysis is based on 44 systematically selected studies covering 66 cases in 21 countries in Africa, Latin America, Southeast Asia, and Eastern Europe. The results show that LSLAs affect rural livelihoods through a small set of archetypical configurations. Adverse livelihood outcomes arise most frequently from processes of (1) enclosure of livelihood assets, (2) elite capture, (3) selective marginalisation of people already living in difficult conditions, and (4) polarisation of development discourses, and less frequently from (5) competitive exclusion, (6) agribusiness failure, and (7) transient jobs. The processes are activated in specific configurations of social-ecological factors. Moving beyond diagnosis, the paper identifies archetypical potentials for safeguarding or enhancing sustainable livelihoods in LSLA target regions at multiple levels of decision-making. Finally, we analyse how contextual factors modify these general insights. This paper helps to advance the archetypes methodology for use in global change research that aims at integral analysis of recurrent patterns expressed in local manifestations. The results can be used to better link local case studies with regional and global inventories of the global land rush. 相似文献
This paper addresses the works of Henri Coudreau, a little‐known French explorer of Guiana and Amazonia who was later forgotten by the ‘heroic’ histories of exploration because of his unruliness and nonconformist attitudes. Drawing on the literature of postcolonialism and tropicality as well as on recent studies of anti‐colonialist geographies, I address for the first time Coudreau's geography from the perspective of anarchist and critical thinking. My main argument is that Coudreau's work is a further example of the complexity and heterogeneity of the European intellectual field during the imperial age. Despite having come of age intellectually among all the European racist and ethnocentric prejudices of his day, Coudreau developed a different outlook thanks to two factors, viz., his personal experience in living for years with the indigenous communities of Amazonia, and his exposure to anarchist anti‐colonialist ideas through his collaboration with Elisée Reclus. Coudreau's tropical utopia of an independent Amazonia, and his endorsement of the stateless nature of local communities, ran counter to French imperial politics, occasioning Coudreau's dismissal from the French administration and his professional exile in Brazil at the time of the Franco‐Brazilian border dispute (1897?1900). 相似文献
Can a sense of ownership over constantly changing urban places be generated through pedestrian exploration and everyday digital media practice? This paper begins with the author’s visit to the city of Adelaide, where a chance encounter – an intriguing sign painted on the wall of a city building – led to a hunt through the city for ghost signs, the remnants of old hand-painted advertisements. This spontaneous activity, combined with the online exploration and image sharing that followed, generated a renewed feeling of connection to, and ownership over, an erstwhile familiar locale. The experience is analysed through the work of theorists investigating change and belonging in modern cities including Guy Debord, Doreen Massey, Michel de Certeau, Andreas Huyssen, and Mark Crinson, as well as the contemporary growth in both politically inspired urban exploring (“Urbex” or “place hacking”) and the digital documentation and sharing of ghost signs and other urban ephemera. 相似文献
Abstract. Coastal benthic communities in soft-bottom deposits of a restricted area were studied by seasonal sampling at nine stations. Faunal assemblages at three different depths were consistently different and exhibited a seasonal pattern of abundance and diversity. Multivariate statistical analyses suggest that each community structure is very similar during the three summer samplings; in autumn and winter many causes of disturbance can disrupt this structure, which is reconstituted the following summer. The stability of benthic communities in this physically variable environment is discussed and a "cyclic" adjustment mechanism of stability is proposed to explain the dynamics of the benthos in this area. 相似文献
A computer program is developed for hull/mooring/riser coupled dynamic analysis of a tanker-based turret-moored FPSO (Floating Production Storage and Offloading) in waves, winds, and currents. In this computer program, the floating body is modeled as a rigid body with six degrees of freedom. The first- and second-order wave forces, added mass, and radiation damping at various yaw angles are calculated from the second-order diffraction/radiation panel program WAMIT. The wind and current forces for various yaw angles of FPSO are modeled following the empirical method suggested by OCIMF (Oil Company International Marine Forum).
The mooring/riser dynamics are modeled using a rod theory and finite element method (FEM), with the governing equations described in a generalized coordinate system. The dynamics of hull, mooring lines, and risers are solved simultaneously at each time step in a combined matrix for the specified connection condition. For illustration, semi-taut chain-steel wire-chain mooring lines and steel catenary risers are employed and their effects on global FPSO hull motions are investigated. To better understand the physics related to the motion characteristics of a turret-moored FPSO, the role of various hydrodynamic contributions is analyzed and assessed including the effects of hull and mooring/riser viscous damping, second-order difference-frequency wave-force quadratic transfer functions, and yaw-angle dependent wave forces and hydrodynamic coefficients. To see the effects of hull and mooring/riser coupling and mooring/riser damping more clearly, the case with no drag forces on those slender members is also investigated. The numerical results are compared with MARIN's wave basin experiments. 相似文献
Pressure variations and three-dimensional effects on liquid sloshing loads in a moving partially filled rectangular tank have been carried out numerically and experimentally. A numerical algorithm based on the volume of fluid (VOF) technique is used to study the non-linear behavior and damping characteristics of liquid sloshing. A moving coordinate system is used to include the non-linearity and avoid the complex boundary conditions of moving walls. The numerical model solves the complete Navier–Stokes equations in primitive variables by using of the finite difference approximations. In order to mitigate a series of discrete impacts, the signal computed is averaged over several time steps. In order to assess the accuracy of the method used, computations are compared with the experimental results. Several configurations of both baffled and unbaffled tanks are studied. Comparisons show good agreement for both impact and non- impact type slosh loads in the cases investigated. 相似文献