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181.
APPLICATION OF ANALYTIC HIERARCHY PROCESS TO ASSESSING THE ECOLOGICAL VULNERABILITY OF WETLANDS IN THE JIANGHAN PLAIN 总被引:4,自引:1,他引:4
WANGXue-lei NINGLong-mei HUWang-bin 《中国地理科学(英文版)》2003,13(3):272-276
Wetlands in the Jianghan Plain are important components of wetland types in lake area in the middle and lower reaches the Changjiang (Yangtze) River and they fulfill many uses and functions related to hydrology,waste assimilation, ecosystem productivity and biodiversity. Owing to natural factors and human activities, especially excessive reclamation from lakes, the shrinking process of the lakes has been accelerated. Wetland ecosystem has shown the characteristics of vulnerability. According to the analysis of wetland ecological function in the Jianghan Plain, this paper presented an index system related to productivity, stability and environmental capacity. By using the method of Analytic Hierarchy Process, we computed the values of the relative weights of the indexes, and evaluated the vulnerability level of the wetland ecosystem by the method of multi-indexes. The case study showed that the fragile extent of wetland ecosystem in the Jianghan Plain is 5.6. This means that the wetland ecosystem in the Jiang-han Plain is laid to the state of middle vulnerability. Therefore, the wetland conservation and eco-rehabilitation in the JiangJaan Plain should be paid attention to. 相似文献
182.
According to B.L. Berry’s “harmonic model,” any natural or social process is a superposition of several cosmic rhythms. The
author assumes that stability of these rhythms allows prediction of earth phenomena over an unlimited time. We show that the
statistical criteria supposedly substantiating the harmonic model were applied incorrectly. The initial data for the analysis
were biased and selected incompetently; the adequacy of the methods used was not verified. Predictions of natural catastrophes
(earthquakes, weather anomalies, etc.) and various social events according to Berry’s model are unsatisfactory. Statistics
do not confirm that these predictions are at least slightly better than random guessing. Berry’s model is unacceptable; it
is untenable both in detail and in general. 相似文献
183.
C. P. Goff L. van Driel-Gesztelyi P. Démoulin J. L. Culhane S. A. Matthews L. K. Harra C. H. Mandrini K. L. Klein H. Kurokawa 《Solar physics》2007,240(2):283-299
A series of flares (GOES class M, M and C) and a CME were observed in close succession on 20 January 2004 in NOAA 10540. Radio
observations, which took the form of types II, III and N bursts, were associated with these events. We use the combined observations
from TRACE, EIT, Hα images from Kwasan, MDI magnetograms and GOES to understand the complex development of this event. Contrary
to a standard interpretation, we conclude that the first two impulsive flares are part of the CME launch process while the
following long-duration event flare represents simply the recovery phase. Observations show that the flare ribbons not only
separate but also shift along the magnetic inversion line so that magnetic reconnection progresses stepwise to neighboring
flux tubes. We conclude that “tether cutting” reconnection in the sheared arcade progressively transforms it to a twisted
flux tube, which becomes unstable, leading to a CME. We interpret the third flare, a long-duration event, as a combination
of the classical two-ribbon flare with the relaxation process following forced reconnection between the expanding CME structure
and neighboring magnetic fields.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
184.
W. Hieke A. Camerlenghi M. B. Cita G. A. Dehghani N. Fusi H. B. Hirschleber L. Mirabile C. Müller A. Polonia 《Marine Geophysical Researches》2009,30(3):161-192
In previous publications, the relationship between the Sirte Abyssal Plain as foreland and the Mediterranean Ridge as accretionary
complex was considered to be simple: the foreland is undeformed, the accretionary complex consumes the foreland, the Messinian
evaporites control the internal structure of the growing complex. The compilation of our own and published data results in
a more complex tectonic pattern and a new geodynamic interpretation. The Sirte Abyssal Plain is imprinted by extensional tectonics
which originated independently from and prior to the approaching process of accretion. The structural setting of the pre-Messinian
and Messinian Sirte Abyssal Plain is responsible for the highly variable thickness of Messinian evaporites. The foreland setting
in the Sirte Abyssal Plain also controls the internal structure of the Mediterranean Ridge, at least between the deformation
front and Bannock Basin, following sediment deformation within the accretionary wedge with a dominating inherited SW-NE orientation.
The taper angle of the post-Messinian Mediterranean Ridge is unusually small compared with other accretionary wedges. In the
studied area, within a distance of about 45 km from the deformation front, there is no appreciable dip in the décollement.
Therefore, the slope of the outer 45 km of the Mediterranean Ridge is considered to be caused only by gravitational spreading
of Messinian evaporites deposited on the slope of pre-Messinian accretionary wedge. As a consequence, the Mediterranean Ridge
underlying such slope is interpreted to belong to the foreland. The allochthonous evaporites overlie autochthonous evaporites
of the Sirte Abyssal Plain. The NE-dipping décollement (and thus of the true tectonically driven deformation front) is expected
to initiate at about the present position of Bannock Basin. The Sirte Abyssal Plain, the adjacent Cyrene Seamount and neighbouring
seafloor relief on the African continental margin are considered to be the product of tectonic segmentation of the continental
crust. 相似文献
185.
Impacts of Climatic Factors on Runoff Coefficients in Source Regions of the Huanghe River 总被引:4,自引:0,他引:4
CHEN Liqun LIU Changming LI Yanping WANG Guoqiang 《中国地理科学(英文版)》2007,17(1):047-055
Runoff coefficients of the source regions of the Huanghe River in 1956–2000 were analyzed in this paper. In the 1990s runoff of Tangnaihai Hydrologic Station of the Huanghe River experienced a serious decrease, which had at- tracted considerable attention. Climate changes have important impact on the water resources availability. From the view of water cycling, runoff coefficients are important indexes of water resources in a particular catchment. Kalinin baseflow separation technique was improved based on the characteristics of precipitation and streamflow. After the separation of runoff coefficient (R/P), baseflow coefficient (Br/P) and direct runoff coefficient (Dr/P) were estimated. Statistic analyses were applied to assessing the impact of precipitation and temperature on runoff coefficients (including Dr/P, Br/P and R/P). The results show that in the source regions of the Huanghe River, mean annual baseflow coefficient was higher than mean annual direct runoff coefficient. Annual runoff coefficients were in direct proportion to annual pre- cipitation and in inverse proportion to annual mean temperature. The decrease of runoff coefficients in the 1990s was closely related to the decrease in precipitation and increase in temperature in the same period. Over different sub-basins of the source regions of the Huanghe River, runoff coefficients responded differently to precipitation and temperature. In the area above Jimai Hydrologic Station where annual mean temperature is –3.9oC, temperature is the main factor in- fluencing the runoff coefficients. Runoff coefficients were in inverse relation to temperature, and precipitation had nearly no impact on runoff coefficients. In subbasin between Jimai and Maqu Hydrologic Station Dr/P was mainly affected by precipitation while R/P and Br/P were both significantly influenced by precipitation and temperature. In the area be-tween Maqu and Tangnaihai hydrologic stations all the three runoff coefficients increased with the rising of annual precipitation, while direct runoff coefficient was inversely proportional to temperature. In the source regions of the Huanghe River with the increase of average annual temperature, the impacts of temperature on runoff coefficients be-come insignificant. 相似文献
186.
B. M. Shustov 《Kinematics and Physics of Celestial Bodies》2016,32(5):218-222
The problem of detecting dangerous (in the sense of a collision with the Earth) celestial bodies of natural origin and the modern concept of building a system of detection of such bodies are discussed. The concept includes two items: remote detection of large (>50 m) hazardous objects providing warning time of several tens of days, which is sufficient to allow the active counteraction and detection of hazardous bodies larger than 10 m in near-Earth space providing warning time of few hours, which is sufficient to issue a warning and to carry out mitigation activities. Some examples of this approach and prospects of the international cooperation are discussed. 相似文献
187.
The coupled mechanics of fluid-filled granular media controls the physics of many Earth systems, for example saturated soils, fault gouge, and landslide shear zones. It is well established that when the pore fluid pressure rises, the shear resistance of fluid-filled granular systems decreases, and, as a result, catastrophic events such as soil liquefaction, earthquakes, and accelerating landslides may be triggered. Alternatively, when the pore pressure drops, the shear resistance of these geosystems increases. Despite the great importance of the coupled mechanics of grain–fluid systems, the basic physics that controls this coupling is far from understood. Fundamental questions that must be addressed include: what are the processes that control pore fluid pressurization and depressurization in response to deformation of the granular skeleton? and how do variations of pore pressure affect the mechanical strength of the grains skeleton? To answer these questions, a formulation for the pore fluid pressure and flow has been developed from mass and momentum conservation, and is coupled with a granular dynamics algorithm that solves the grain dynamics, to form a fully coupled model. The pore fluid formulation reveals that the evolution of pore pressure obeys viscoelastic rheology in response to pore space variations. Under undrained conditions elastic-like behavior dominates and leads to a linear relationship between pore pressure and overall volumetric strain. Viscous-like behavior dominates under well-drained conditions and leads to a linear relationship between pore pressure and volumetric strain rate. Numerical simulations reveal the possibility of liquefaction under drained and initially over-compacted conditions, which were often believed to be resistant to liquefaction. Under such conditions liquefaction occurs during short compactive phases that punctuate the overall dilative trend. In addition, the previously recognized generation of elevated pore pressure under undrained compactive conditions is observed. Simulations also show that during liquefaction events stress chains are detached, the external load becomes completely supported by the pressurized pore fluid, and shear resistance vanishes. 相似文献
188.
P. Bogaert D. Fasbender 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(6):695-709
In spite of the exponential growth in the amount of data that one may expect to provide greater modeling and predictions opportunities,
the number and diversity of sources over which this information is fragmented is growing at an even faster rate. As a consequence,
there is real need for methods that aim at reconciling them inside an epistemically sound theoretical framework. In a statistical
spatial prediction framework, classical methods are based on a multivariate approach of the problem, at the price of strong
modeling hypotheses. Though new avenues have been recently opened by focusing on the integration of uncertain data sources,
to the best of our knowledges there have been no systematic attemps to explicitly account for information redundancy through
a data fusion procedure. Starting from the simple concept of measurement errors, this paper proposes an approach for integrating
multiple information processing as a part of the prediction process itself through a Bayesian approach. A general formulation
is first proposed for deriving the prediction distribution of a continuous variable of interest at unsampled locations using
on more or less uncertain (soft) information at neighboring locations. The case of multiple information is then considered,
with a Bayesian solution to the problem of fusing multiple information that are provided as separate conditional probability
distributions. Well-known methods and results are derived as limit cases. The convenient hypothesis of conditional independence
is discussed by the light of information theory and maximum entropy principle, and a methodology is suggested for the optimal
selection of the most informative subset of information, if needed. Based on a synthetic case study, an application of the
methodology is presented and discussed. 相似文献
189.
V. V. Aristov I. I. Babarina A. V. Grigor’eva V. Yu. Alekseev V. Yu. Prokof’ev A. A. Uzyunkoyan O. V. Zabolotskaya S. G. Titov 《Geology of Ore Deposits》2017,59(1):68-101
Gold deposits and occurrences small in reserves and high in Au grade conventionally determine the line of prospecting in terrigenous sequences of the Verkhoyansk–Kolyma region. In this paper, the geological structure of such gold objects is considered with the example of the deposits and prospects making up the Zhdaninsky ore–placer cluster in the Republic of Sakha (Yakuia). From lithological, structural, and mineralogical–geochemical data, the formation conditions of ore-bearing complexes are specified, the geological evolution history of the northern Ol’chan Zone of the Kular–Nera Belt is reconstructed, and the zonal distribution of mineralization within the ore–placer cluster is revealed. The structural–compositional complexes were formed in the following succession: (1) sedimentation at the shelf of the passive margin accompanied by synsedimentation deformations; (2) metagenesis of sediments and the development of bedding-plane intraformational detachments of collision stage D1 under conditions of tangential compression and accompanied by the formation of carbon dioxide–aqueous metamorphic fluid at a temperature of 300°C and under a pressure of 1.4 kbar; (3) folding and faulting of orogenic stage D2 with the formation of synkinematic magmatic bodies, metasomatic alteration, and Au-bearig mineral assemblages. Small Au-bearing objects with veined mineralization and high Au grade are localized in structures of stage D2 transverse to bedding-plane schistosity S1. They form at the collision stage above intraformational detachment surfaces and are controlled by shear structures of the orogenic stage with misalignment of these deformations. The ore zoning is determined by the distribution of Co and Ni minerals and by variations in the anionic composition of ore (S, As, Sb). 相似文献
190.
Amphioxus, a cephalochordate, is an important model fish for studies in evolution and comparative biology. A successful cell
culture from amphioxus tissues in vitro would help understanding some basic issues. To determine the optimal culture conditions for proliferation of amphioxus cells,
primary cultures were initiated from buccal cirri, tail, gill, gut and metapleural fold of amphioxus Branchiostoma belcheri tsingtauense. The media tested were L-15, F-12, M 199, MEM, DMEM, PRMI 1640 and LDF, each was supplemented with 20% fetal bovine serum.
The optimal conditions include tail tissue cultured in L-15 or F-12 with supplement of 20% FBS and 1.5% NaCl at about 25°C.
Supported by Doctoral Initial Fund of Ludong University (No.43304) 相似文献