排序方式： 共有68条查询结果，搜索用时 15 毫秒
41.
Numerical model of antecedent rainfall effect on slope stability at a hillslope of weathered granitic soil formation 总被引：2，自引：0，他引：2
Modeling rainwater infiltration in slopes is vital to the analysis of slope failure induced by heavy rainfall. Although the significance of rainwater infiltration in causing landslides is widely recognized, there have been different conclusions as to the relative roles of antecedent rainfall to slope failure. In this study, a numerical model was developed to estimate the effect of antecedent rainfall on an unsaturated slope, the formation of a saturated zone, and the change in slope stability under weak rainfall and rainstorm event. Results showed that under a rainstorm event, slope failure occurred at comparably similar time although the antecedent rainfall drainage periods prior to the major rainfall were different (i.e., 24-h, 48-h and 96-h). However, under weak rainfall condition, differences of the antecedent rainfall drainage periods have significant effect on development of pore-water pressure. A higher initial soil moisture conditions caused faster increase in pore water pressure and thus decreasing the safety factor of the slope eventually increasing likelihood of slope failure. 相似文献
42.
The ordinary least square method (OLS) has been the most frequently used least square method in hydrological data analysis. Its computational algorithm is simple, and the error analysis is also simple and clear. However, the primary assumption of the OLS method, which states that the dependent variable is the only error‐contaminated variable and all other variables are error free, is often violated in hydrological data analyses. Recently, a matrix algorithm using the singular value decomposition for the total least square (TLS) method has been developed and used in data analyses as errors‐in‐variables model where several variables could be contaminated with observational errors. In our study, the algorithm of the TLS is introduced in the evaluation of rating curves between the flow discharge and the water level. Then, the TLS algorithm is applied to real data set for rating curves. The evaluated TLS rating curves are compared with the OLS rating curves, and the result indicates that the TLS rating curve and the OLS rating curve are in good agreement. The TLS and OLS rating curves are discussed about their algorithms and error terms in the study. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
43.
Taha Rabeh Joao Carvalho Ahmed Khalil Esmat A. El-Aal Ibrahim El-Hemaly 《Acta Geophysica》2011,59(5):1044-1056
When the solar irradiance propagates between the outer magnetospheric regions and the ionosphere, dynamic processes of the
magnetosphere-ionosphere-thermosphere system are affected at the lower end of their paths by the interaction of radiation
with the neutral troposphere. The main target of this work is to investigate the relationship between the diurnal magnetic
field variations resulting from solar activities and the variation in the troposphere temperature. Meteorological and geomagnetic
data acquired from different observatories located in Egypt, Portugal and Slovakia in a long-term and daily-term scales were
analyzed. 相似文献
44.
Approaches to improve the governance of social–ecological systems are difficult to define in situations where governance is weak, that is, involving limited interactions between the actors and weak management of natural resources. This article analyzes an action research process implemented in the Chaouia coastal region of Morocco, where weak governance of the social–ecological system led to a groundwater and agricultural crisis. A dialogue between local actors was set up with the aim of identifying strategies to address the crisis. First separately and then together, farmers’ groups and staff members of public organizations analyzed the existing situation, scenarios for the future of the area, and strategies to cope with the crisis. Contrary to the expectations of the participants, farmers and staff members of public organizations had productive discussions. This approach clarified how social learning can be achieved and governance improved in this situation of weak governance. 相似文献
45.
The performance of a Wells turbine with various non-uniform tip clearances was investigated using computational fluid dynamics (CFD). The investigation was performed on numerical models of a NACA0020 blade profile under steady flow conditions. The performance of turbines with uniform and non-uniform tip clearances was compared. The results were also compared with experimental results in literature. It was shown that the performance of turbine with non-uniform tip clearance is similar with that of turbine with uniform one in terms of torque coefficient, input power coefficient, and efficiency. However, the turbine with non-uniform tip clearance seems to have a preferable overall performance. An investigation on the flow-field around the turbine blade was performed in order to explain the phenomena. 相似文献
46.
Many soil–structure interaction problems require the knowledge of the shear resistance and behavior between the soil and construction materials. Although sensitive marine clay deposits are widely found in Canada (Leda clay) and many regions in the world (e.g., Scandinavia), and steel is a common construction material for many civil engineering structures, our understanding of the interface shear behavior between sensitive marine clay and steel is still limited. This paper presents the results of an experimental study on the interface shear behavior between Leda clay and steel. In this research, direct shear tests (DSTs) are conducted to investigate the interface shear strength parameters and behavior between Leda clay and steel, and the effect of several factors (e.g., steel surface roughness, properties of the Leda clay) on the interface shear behavior and parameters. All tests have been carried out with a standard DST apparatus at normal loads which range from 250 to 450 kPa. The results show that the Leda clay interface shear behavior can be significantly affected by the steel surface roughness, the Leda clay’s OCR, dry density, and salt content. The results presented in this paper will contribute to a more cost-effective design of geotechnical structures in Leda clay. 相似文献
47.
Tenfold cross validation artificial neural network modeling of the settlement behavior of a stone column under a highway embankment 总被引：1，自引：1，他引：0
Zamri Chik Qasim A. Aljanabi Anuar Kasa Mohd Raihan Taha 《Arabian Journal of Geosciences》2014,7(11):4877-4887
Construction of embankments in engineering structures on soft clay soils normally encounters problems related to excessive settlement issues. The conventional methods are inadequate to analyze and predict the surface settlement when the necessary parameters are difficult to determine in the field and in the laboratory. In this study, artificial neural network systems (ANNs) were used to predict settlement under embankment load using soft soil properties together with various geometric parameters as input for each stone column (SC) arrangement and embankment condition. Data from a highway project called Lebuhraya Pantai Timur2 in Terengganu, Malaysia, were investigated. The FEM package of Plaxis v8 program analysis was utilized. The actual angle of internal friction, spacing between SC, diameter of SC, length of SC, and height of embankment were used as the input parameters, and the settlement was used as the main output. Non cross validation (NCV) and tenfold cross validation (TFCV) were used to build the ANN model. The results of the TFCV model were more accurate than those of the NCV model. Comparisons made with the predictions of the Priebe model showed that the proposed TFCV model could provide better predictions than conventional methods. 相似文献
48.
Tectonic model of Egypt based on magnetic analysis 总被引：1，自引：0，他引：1
The main target of this work was to study the dynamics of the Earth’s crust for Egypt based on the magnetic survey. High-resolution
land magnetic data were analyzed, combined with the results of GPS and seismic stress analyses.
The constructed tectonic map shows that the N35°-N45°W trend of the structure (related to the Red Sea and Gulf of Suez tectonics)
predominates along the Gulf of Suez, Red Sea, covering wide parts of the study area. The N45°-N65°E tectonic trend (related
to the Syrian Arc tectonics), prevailing in the northern part of Egypt, is of the second rank. The Aqaba (N15°-25°E) and E-W
trends prevail in the northern part and along the transition zone of stable/unstable shelves. The depth to the basement rocks
ranges from the surface along the Red Sea and southern parts of Egypt to more than 4 km below sea level at the northern part
of the study area. 相似文献
49.
Mouloud Tribeche Smain Younsi Taha Houssine Zerguini 《Astrophysics and Space Science》2012,339(2):243-247
Arbitrary amplitude dust-acoustic double-layers (DA-DLs) in a plasma with suprathermal electrons, two-temperature thermal
ions, and warm drifting dust grains are investigated. Our results reveal that the spatial patterns of the DA-DLs are affected
by the degree of the electron suprathermality. The electron thermalization involves a decrease of the cold ion component density,
for the existence of localized DA-DLs. An increase of the dust drift velocity requires a decrease of κ (the electron spectral index), for the onset of dust-acoustic double-layers. An increase of the Mach number M leads to an increase of the DL amplitude as well as the corresponding electron spectral index for which the DL occurs. 相似文献
50.
Ziad Mahmoud Mansour Mohd Raihan Taha Zamri Chik Anuar Kasa 《Environmental Earth Sciences》2009,59(4):891-900
Leaching of Lisan Marl, Dead Sea, Jordan increased the soil compressibility and cohesion intercept. Back analysis using the
Plaxis finite element code was successfully implemented. The Finite element modeling of dike construction showed a significant
increase of total settlement and negligible effect on the strength as calculated by the φ/c reduction method. The height of dikes to be constructed on Lisan Marl as foundation material, should be optimized to account
for the effect of soluble salts leaching. For this to take place, an accurate calculation of settlement is crucial. 相似文献