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81.
Sadeghi Farhang Monjezi Masoud Jahed Armaghani Danial 《Natural Resources Research》2020,29(2):887-903
Natural Resources Research - Drilling and blasting operations are one of the most effective techniques for rock removal in mines. However, these operations are associated with some environmental... 相似文献
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Natural Resources Research - Fractal/multifractal modeling is a widely used geomathematical approach to capturing different populations in geochemical mapping. The rationale of this methodology is... 相似文献
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84.
Jafar Sadeghi Martiros Khurshudyan Margarit Hakobyan Hoda Farahani 《天文和天体物理学研究(英文版)》2015,(2):175-190
We consider a tachyonic scalar field as a model of dark energy with interaction between components in the case of variable G and Λ. We assume a flat Universe with a specific form of scale factor and study cosmological parameters numerically and graphically. Statefinder analysis is also performed. For a particular choice of interaction parameters we succeed in obtaining an analytical expression of densities. We find that our model will be stable at the late stage but there is an instability in the early Universe, so we propose this model as a realistic model of our Universe. 相似文献
85.
Strain energy concept has been employed by the researchers for the assessment of liquefaction phenomenon which is a disastrous type of earthquake-induced failure in saturated soils. The efficiency and predictability conditions of strain energy concept for liquefaction potential assessment are investigated herein using effective stress numerical analyses. Several earthquake ground motions were introduced to the base of a calibrated numerical model using an advanced fully coupled constitutive model. Results of the numerical analyses indicate that earthquake-induced excess pore pressure is more rigorously proportional to strain energy compared with the other examined intensity measures. Subsequently, a simple relationship was derived using the results of dynamic analyses to predict cumulative strain energy density in terms of magnitude, source to site distance, and effective overburden pressure. This relationship, which tries to guarantee the predictability condition of strain energy demand, has demonstrated a successful capability in discrimination between the liquefied and non-liquefied case histories recorded after several well-known earthquakes. This study has provided a practical linkage between numerical analysis and field observations. Finally, it is concluded that although strain energy approach possesses a great conceptual efficiency in liquefaction potential assessment, its precise prediction in actual field conditions involves some difficulties. 相似文献
86.
Phosphorus desorption kinetics in two calcareous soils amended with P fertilizer and organic matter 总被引：2，自引：1，他引：1
We studied the effects of poultry manure and pistachio compost with and without phosphorus fertilizer on the kinetics of phosphorus
desorption in two calcareous soils of Kerman and Koohbanan farms in the southeastern of Iran. For this purpose mono potassium
phosphate, at rates of 0, and 100 parts per million of phosphorus, and air-dried manure, at rates of 0 and 4% were mixed with
the soils. The soils were incubated at 24–25°C and near field capacity for 90 days in the greenhouse. Afterwards, the desorption
of P was studied by the successive extraction with 0.5 M NaHCO3. The results of this research indicated that application of OM and fertilizer P combined increased P recovery in each of
the extraction time, adding poultry manure and 100 mg phosphorus together to the soils, increased P desorption more than pistachio
compost in the soils. The phosphorus desorption rate was initially rapid and then became slower until equilibrium was approached.
Kinetic data were best described by power function and simple Elovich equations. Subsequent to these equations, parabolic
diffusion equation was also well fitted the time-dependent P desorption data. 相似文献
87.
A Bonded Particle Model Simulation of Shear Strength and Asperity Degradation for Rough Rock Fractures 总被引：3，自引：3，他引：0
Mohammad Sadegh Asadi Vamegh Rasouli Giovanni Barla 《Rock Mechanics and Rock Engineering》2012,45(5):649-675
Different failure modes during fracture shearing have been introduced including normal dilation or sliding, asperity cut-off and degradation. Attempts have been made to study these mechanisms using analytical, experimental and numerical methods. However, the majority of the existing models simplify the problem, which leads to unrealistic results. With this in mind, the aim of this paper is to simulate the mechanical behaviour of synthetic and rock fracture profiles during direct shear tests by using the two-dimensional particle flow computer code PFC2D. Correlations between the simulated peak shear strength and the fracture roughness parameter D R1 recently proposed by Rasouli and Harrison (2010) are developed. Shear test simulations are carried out with PFC2D and the effects of the geometrical features as well as the model micro-properties on the fracture shear behaviour are studied. The shear strength and asperity degradation processes of synthetic profiles including triangular, sinusoidal and randomly generated profiles are analysed. Different failure modes including asperity sliding, cut-off, and asperity degradation are explicitly observed and compared with the available models. The D R1 parameter is applied to the analysis of synthetic and rock fracture profiles. Accordingly, correlations are developed between D R1 and the peak shear strength obtained from simulations and by using analytical solutions. The results are shown to be in good agreement with the basic understanding of rock fracture shear behaviour and asperity contact degradation. 相似文献
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AbstractThe sediment yield model of the MUSLE (modified universal soil loss equation) is applied extensively throughout the world, but different performances have been reported of its success relative to measured data. A review of all the available literature is presented to assess the application of the model under different conditions and, ultimately, make a comprehensive judgement on the different aspects to allow readers to adjust their further research. A review of 49 papers showed the variable accuracy of the model, which depends on the manner of calculation and determination of the input and output, and the study time and space scales. There were differences in land use, in correspondence of the physiographic characteristics with those of the original conditions of model development, and even in the experience of researchers in applying the model. The results also show the need to consider the original application of the model, as proposed by its developers, to achieve comparable results.Editor Z.W. KundzewiczCitation Sadeghi, S.H.R., et al., 2014. A review of the application of the MUSLE model worldwide. Hydrological Sciences Journal, 59 (2), 365–375. 相似文献
90.
Taravatrooy Narges Nikoo Mohammad Reza Sadegh Mojtaba Parvinnia Mohammad 《Natural Hazards》2018,93(2):905-920
In many parts of Canada, limited data are available for hydrodynamic model inputs, and the ability to generate quality flood grids through 1D, 2D or 3D methods is nonviable. In this paper, the capability of simplified flood models, which rely solely on digital terrain models (DTMs), was explored to assess the quality and speed of their results. Results were validated against historic floods in two locations. Three non-physics-based simplified conceptual flood models were tested: (1) planar method, (2) inclined plane and (3) height above nearest drainage network (HAND) model. The accuracy and performance were evaluated using three criteria: inundation extent, water depth and computation time. Findings show that the HAND model is the best predictor of inundation extent, with Probability of Detection and Critical Success Index being higher than 0.90 in both study areas. Though the preprocessing time for the HAND model is lengthy, once completed, the time to simulate flooding at a variety of water levels is rapid, making this model the most suitable choice for web-based, on-demand flood inundation mapping. Knowledge of the fit of these flood models and associated uncertainty can be helpful to emergency managers such that they can better understand exposure and vulnerability while preparing flood response plans. 相似文献