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21.
Fazlur-Rahman 《山地科学学报》2007,4(4):331-343
Pakistan is predominantly a mountainous country where rural development activities are characterised by inconsistency, politically motivated short-term projects without proper feedback. Since the inception of the country, the top-down approach has been followed, and the same development plans that were formulated for the plain areas have been extended to the mountains without any modification. In doing so, neither the participation of the local communities was cared for, nor the mountain specificities were considered in the planning process. Moreover, the representation of the local inhabitants was improper and contradictory to the facts. This biased approach has been one of the main causes for the failure of development projects carried out by different agencies of the Government. Contrary to the perception of the state authorities, the mountain communities proved to be more open to accept new approaches and demonstrated the capacity and capability of being a dependable development partner. In this paper, a detailed account of the Aga Khan Rural Support Programme (AKRSP) has been presented to assess and evaluate the approach followed by this non-governmental organisation (NGO), and the response of the local inhabitants as collaborators in the development process. The achievements of the AKRSP from project planning, implementation and monitoring can be adopted as a model for rural development not only in the plains, but also in the mountainous areas of the developing countries in the world. 相似文献
22.
In this paper the second order characteristic (discontinuous bifurcation) condition is derived for the granular flow (fully plastic) equations. This second order bifurcation equation is shown to be formally identical to the first order localization requirement during steady elastoplastic deformation provided the elastic compliance tensor is substituted for the product of the plastic multiplier with the flow Hessian. For isotropic yield and flow functions the invariant form of the characteristic condition is given in detail, as well as an alternative expression in adapted co‐ordinates. The characteristic condition can be regarded as defining a hardening function which is maximized to identify the critical angles. When the method is applied to 3D Coulomb flow, Mohr's 3D fracture plane conditions are obtained uniquely. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
23.
In this paper, we present 50 surface water samples collected during the IMAGES III cruise (June–July 1997) along a transect from New Zealand to the China Sea (42°S–178°E, 21°N–120°E) covering a temperature range from 13.3 to 30.4 °C. A very worthwhile aspect of this study is a coupling of both biomarker (alkenone) and coccolithophorid counting. We show that the U37k′–temperature relationship is very similar to the Prahl et al. [Geochim. Cosmochim. Acta 52 (1988) 2203] culture calibration and to the global core top calibration of Müller et al. [Geochim. Cosmochim. Acta 62 (1998) 1757]. However, in the warmest surface waters of the Western Pacific ocean (>26.4 °C) where Gephyrocapsa oceanica is likely the most widespread species, the associated U37k′ has a constant value of 1.0. The consequence is that above this temperature threshold, U37k′ cannot be used as an accurate paleothermometer. 相似文献
24.
Burkhard Fuchs 《Astrophysics and Space Science》2003,284(2):719-722
An update of the set of low surface brightness galaxies is presented which can be used to set constraints on the otherwise
ambiguous decompositions of their rotation curves into contributions due to the various components of the galaxies. The selected
galaxies show all clear spiral structure and arguments of density wave theory of galactic spiral arms are used to estimate
the masses of the galactic disks. Again these estimates seem to indicate that the disks of low surface brightness galaxies
might be much more massive than currently thought. This puzzling result contradicts stellar population synthesis models. This
would mean also that low surface brightness galaxies are not dominated by dark matter in their inner parts.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
25.
M.L. Litvak I.G. Mitrofanov A.B. Sanin W.V. Boynton D. Hamara R.S. Saunders 《Icarus》2006,180(1):23-37
In this paper, we have analyzed neutron spectroscopy data gathered by the High Energy Neutron Detector (HEND) instrument onboard Mars Odyssey for comparison of polar regions. It is known that observation of the neutron albedo of Mars provides important information about the distribution of water-ice in subsurface layers and about peculiarities of the CO2 seasonal cycle. It was found that there are large water-rich permafrost areas with contents of up to ∼50% water by mass fraction at both the north and south Mars polar regions. The water-ice layers at high northern latitudes are placed close to the surface, but in the south they are covered by a dry and relatively thick (10-20 cm) layer of soil. Analysis of temporal variations of neutron flux between summer and winter seasons allowed the estimation of the masses of the CO2 deposits which seasonally condense at the polar regions. The total mass of the southern seasonal deposition was estimated as 6.3×1015 kg, which is larger than the total mass of the seasonal deposition at the north by 40-50%. These results are in good agreement with predictions from the NASA Ames Research Center General Circulation Model (GCM). But, the dynamics of the condensation and sublimation processes are not quite as consistent with these models: the peak accumulation of the condensed mass of CO2 occurred 10-15 degrees of Ls later than is predicted by the GCM. 相似文献
26.
A new model of albedo and emissivity of planetary surfaces covered by volatile ices in the form of porous slab-like deposits is described. In the model, a radiative transfer model is coupled with a microphysical model in order to link changes in albedo and emissivity to changes in porosity caused by ice metamorphism. Preliminary results for Triton, Pluto, and Io are presented (the martian CO2 caps will be the subject of a separate publication). The coupled model will aid in the interpretation of ground-based and spacecraft observations and should lead to advances in surface and atmospheric modeling. 相似文献
27.
There is a general belief that hydrous minerals cannot exist on Venus under current surface conditions. This view was challenged when Johnson and Fegley (2000, Icarus 146, 301-306) showed that tremolite (Ca2Mg5Si8O22(OH)2), a hydrous mineral, is stable against thermal decomposition at current Venus surface temperatures, e.g., 50% decomposition in 4 Ga at 740 K. To further explore hydrous mineral thermal stability on Venus, we experimentally determined the thermal decomposition kinetics of fluorine-bearing tremolite. Fluor-tremolite is thermodynamically more stable than OH-tremolite and should decompose more slowly. However how much slower was unknown. We measured the decomposition rate of fluorine-bearing tremolite and show that its decomposition is several times to greater than ten times slower than that of OH-tremolite. We also show that F-bearing tremolite is depleted in fluorine after decomposition and that fluorine is lost as a volatile species such as HF gas. If tremolite ever formed on Venus, it would probably also contain fluorine. The exceptional stability of F-bearing tremolite strengthens our conclusions that if hydrous minerals ever formed on Venus, they could still be there today. 相似文献
28.
This paper is a continuation of previous research, which obtained a convenient solution for arbitrary surface fluxes before ponding. By means of Fourier Transformation this has been extended to derive analytical solutions of a linearized Richards' equation for arbitrary input fluxes after surface saturation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
29.
长江三峡工程地壳形变监测网络 总被引:19,自引:10,他引:9
长江三峡工程地壳形变监测网络,采用了当今高精度GPS、INSAR空间大地测量技术,并与精密水准测量,精密重力测量,精密激光测距和峒体连续形变监测等技术相结合,构成一个空间上点、线、面结合,时间上长、中、短兼顾的高精度,高时空分辨率的地壳形变监测网络。该网络既可获取三峡库区特别是库首区区域形变场和区域应变场的动态变化,监测库区主要断层活动,为水库诱发地震预测及研究服务,又可用于气象、滑坡地质灾害监测等,该监测网络于1997年底开始建设,2001年6月建成,到目前为止,已获得大量宝贵的观测资料,必将产生显著的经济效益和社会效益。 相似文献
30.