Spatial changes of Extended De Martonne climatic zones affected by climate change in Iran   总被引：1，自引：1，他引：0  

Jaber Rahimi  Meisam Ebrahimpour  Ali Khalili 《Theoretical and Applied Climatology》2013,112(3-4):409-418

In order to better understand the effect associated with global climate change on Iran’s climate condition, it is important to quantify possible shifts in different climatic types in the future. To this end, monthly mean minimum and maximum temperature, and precipitation from 181 synoptic meteorological stations (average 1970–2005) have been collected from the meteorological organization of Iran. In this paper, to study spatial changes of Iran’s climatic zones affected by climate changes, Extended De Martonne’s classification (originally formulated by De Martonne and extended by Khalili (1992)) was used. Climate change scenarios were simulated in two future climates (average conditions during the 2050s and the 2080s) under each of the SRES A1B and A2, for the CSIRO-MK3, HadCM3, and CGCM3 climate models. Coarse outputs of GCMs were downscaled by delta method. We produced all maps for three time periods (one for the current and two for the future) according to Extended De Martonne’s classification. Finally, for each climatic zone, changes between the current and the future were compared. As the main result, simulated changes indicate shifts to warmer and drier zones. For example, in the current, extra arid-cold (A1.1m2) climate is covering the largest area of the country (21.4 %), whereas in both A1B and A2 scenarios in the 2050s and the 2080s, extra arid-moderate (A1.1m3) and extra arid-warm (A1.1m4) will be the climate and will occupy the largest area of the country, about 21 and 38 %, respectively. This analysis suggests that the global climate change will have a profound effect on the future distribution of severe aridity in Iran.  相似文献   

Effective field theory calculation of two-deuteron radiative capture reaction at astrophysical energies     

H. Sadeghi  H. Khalili 《Astrophysics and Space Science》2014,352(2):637-643

Two-deuteron radiative capture reaction is one of the deuterium-burning processes that the cross section is not well known at very low-energies. We develop the formalism based on pionless Effective Field Theory (EFT) for deuteron–deuteron (dd) scattering to derive the cross section of two-deuteron radiative capture. Within this formalism the two- and three-body forces, should also be included in the capture cross section calculations. The aim of the present work is to calculate the observables of the low-energy dd photonuclear reactions. The cross section and the astrophysical S-factor for the ²H(d,γ)⁴He reaction have been calculated. The ⁴He is studied as four-body bound states in the pionless EFT. The theoretical uncertainties for observables are estimated based on the variation of the cutoffs. The astrophysical S-factor is accurately determined to be 6.9×10^?6 keV?b (6.1×10^?6 keV?b) for two-body (two- and three-body) at zero energy. A satisfactory agreement between theory and experiment for dd radiative capture observables up to order of calculation has been found by insertion of three-body force.  相似文献   

Isospin violation in the d(n,γ)~3 H process at energies relevant for big bang nucleosynthesis     

Hossein Sadeghi  Hassan Khalili  Mojtaba Godarzi 《中国天文和天体物理学报》2014,(3):357-366

The cross section for a neutron-deuteron(nd) radiative capture is calculated using the pionless effective field theory including isospin symmetry breaking(ISB) corrections up to higher order.The triton is studied as a three-body bound state and one has to take into account various ISB effects,relativistic corrections and external electromagnetic currents.The isospin violation in nd radiative capture is improved compared to the one at NLO and N2LO.The cross section is determined to beσtot= [0.505 ± 0.003] mb up to N2LO.A satisfactory agreement between theory and experiment for the calculated cross section has been found by insertion of three-body forces and ISB effects.  相似文献   

Scattering and diffraction of plane SH-waves by two-dimensional inhomogeneities: Part I     

Nasser Moeen-Vaziri  Mihailo D. Trifunac 《Soil Dynamics and Earthquake Engineering》1988,7(4):179-188

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Drained cavity expansion in sands exhibiting particle crushing     

A. R. Russell  N. Khalili 《国际地质力学数值与分析法杂志》2002,26(4):323-340

The expansion of cylindrical and spherical cavities in sands is modelled using similarity solutions. The conventional Mohr–Coulomb failure criterion and the state parameter sand behaviour model, which enables hardening–softening, are used in the analysis. The sand state is defined in terms of a new critical state line, designed to account for the three different modes of compressive deformation observed in sands across a wide range of stresses including particle rearrangement, particle crushing and pseudoelastic deformation. Solutions are generated for cavities expanded from zero and finite radii and are compared to those solutions where a conventional critical state line has been used. It is shown that for initial states typical of real quartz sand deposits, pseudoelastic deformation does not occur around an expanding cavity. Particle crushing does occur at these states and causes a reduction in the stress surrounding the cavity. This has major implications when using cavity expansion theory to interpret the cone penetration test and pressuremeter test. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Quantitative geophysical pore‐type characterization and its geological implication in carbonate reservoirs     

Luanxiao Zhao  Mosab Nasser  De‐hua Han 《Geophysical Prospecting》2013,61(4):827-841

This paper discusses and addresses two questions in carbonate reservoir characterization: how to characterize pore‐type distribution quantitatively from well observations and seismic data based on geologic understanding of the reservoir and what geological implications stand behind the pore‐type distribution in carbonate reservoirs. To answer these questions, three geophysical pore types (reference pores, stiff pores and cracks) are defined to represent the average elastic effective properties of complex pore structures. The variability of elastic properties in carbonates can be quantified using a rock physics scheme associated with different volume fractions of geophysical pore types. We also explore the likely geological processes in carbonates based on the proposed rock physics template. The pore‐type inversion result from well log data fits well with the pore geometry revealed by a FMI log and core information. Furthermore, the S‐wave prediction based on the pore‐type inversion result also shows better agreement than the Greensberg‐Castagna relationship, suggesting the potential of this rock physics scheme to characterize the porosity heterogeneity in carbonate reservoirs. We also apply an inversion technique to quantitatively map the geophysical pore‐type distribution from a 2D seismic data set in a carbonate reservoir offshore Brazil. The spatial distributions of the geophysical pore type contain clues about the geological history that overprinted these rocks. Therefore, we analyse how the likely geological processes redistribute pore space of the reservoir rock from the initial depositional porosity and in turn how they impact the reservoir quality.  相似文献   

Metacraton: Nature,genesis and behavior     

Jean-Paul Liégeois  Mohamed G. Abdelsalam  Nasser Ennih  Aziouz Ouabadi 《Gondwana Research》2013,23(1):220-237

In this paper, we show with examples that cratons involved in intercontinental collisions in a lower plate position are often affected by orogenic events, leading to the transformation of their margins. In some cases, craton interiors can also be shaped by intense collisional processes, leading to the generation of intracratonic orogenic belts. We propose to call these events “metacratonization” and the resulting lithospheric tract “metacraton”. Metacratons can appear similar to typical orogenic belts (i.e. active margin transformed by collisional processes) but are actually sharply different. Their main distinctive characteristics (not all are present in each metacraton) are: (1) absence of pre-collisional events; (2) absence of lithospheric thickening, high-pressure metamorphism being generated by subduction, leading to high gradient in strain and metamorphic intensity; (3) preservation of allochthonous pre-collisional oceanic terranes; (4) abundant post-collisional magmatism associated with shear zones but not with lithospheric thickening; (5) presence of high-temperature–low-pressure metamorphism associated with post-collisional magmatism; (6) intracontinental orogenic belts unrelated to subduction and oceanic basin closures. Reactivation of the rigid but fractured metacratonic lithosphere will cause doming, asthenospheric volcanism emplacement, and mineralizations due to repetitive mineral enrichments. This paper provides several geological cases exemplifying these different metacratonic features in Scandinavia, Sahara, Central Africa and elsewhere. A special focus is given to the Saharan Metacraton because it is where the term “metacraton” originated and it is a vastly expanded tract of continental crust (5,000,000 km²). Metacratonization is a common process in the Earth's history. Considering the metacraton concept in geological studies is crucial for understanding the behavior of cratons and their partial destruction.  相似文献   

Investigation of spatio-temporal patterns of seasonal streamflow droughts in a semi-arid region     

Saadat  Samane  Khalili  Davar  Kamgar-Haghighi  Ali Akbar  Zand-Parsa  Shahrokh 《Natural Hazards》2013,69(3):1697-1720

Natural Hazards - Spatio-temporal patterns of seasonal streamflow droughts were investigated for the semi-arid Karkheh watershed, located in western Iran with an area of 41,470 km2,...  相似文献   

Effects of Operational Parameters on Decolorization of C. I. Acid Red 88 by UV/H2O2 Process: Evaluation of Electrical Energy Consumption     

Nasser Modirshahla  Mohammad A. Behnajady  Rajab Rahbarfam  Aydin Hassani 《洁净——土壤、空气、水》2012,40(3):298-302

In the present study, effects of operational parameters on the electrical energy consumption for photooxidative process (UV/H₂O₂) for the decolorization of C. I. Acid Red 88 (AR88) have been investigated. In a series of experiments, 20 mg L^?1 of AR88 solution were irradiated in the presence of different concentrations of H₂O₂ (to find out optimum amount of H₂O₂) by UV light intensity of 30 W m^?2 for certain irradiation times. The decolorization of the dye followed pseudo first‐order kinetics, and hence, the figure‐of‐merit electrical energy per order (E_EO) is appropriate for estimating the electrical energy efficiency. The electrical energy consumption was determined during the variation of some parameters such as initial H₂O₂ concentration, initial dye concentration, UV light intensity, pH, and the gap size of solution. Results showed that electrical energy could be reduced by optimizing operational parameters.  相似文献   

Investigation of spatial and temporal variability of precipitation in Iran over the last half century   总被引：4，自引：1，他引：3  

Keivan Khalili  Mohammad Nazeri Tahoudi  Rasoul Mirabbasi  Farshad Ahmadi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(4):1205-1221

Investigation of the precipitation phenomenon as one of the most important meteorological factors directly affecting access to water resources is of paramount importance. In this study, the precipitation concentration index (PCI) was calculated using annual precipitation data from 34 synoptic stations of Iran over a 50-year period (1961–2010). The trend of precipitation and the PCI index were analyzed using the Mann–Kendall test after removing the effect of autocorrelation coefficients in annual and seasonal time scales. The results of zoning the studied index at annual time scale revealed that precipitation concentration follows a similar trend within two 25-year subscales. Furthermore, the PCI index in central and southern regions of the country, including the stations of Kerman, Bandarabbas, Yazd, Zahedan, Shahrekord, Birjand, Bushehr, Ahwaz, and Esfahan indicates a strong irregularity and high concentration in atmospheric precipitations. In annual time scale, none of the studied stations, had shown regular concentration (PCI < 10). Analyzing the trend of PCI index during the period of 1961–2010 witnessed an insignificant increasing (decreasing) trend in 16 (15) stations for winter season, respectively, while it faced a significant negative trend in Dezful, Saghez, and Hamedan stations. Similarly, in spring, Kerman and Ramsar stations exhibited a significant increasing trend in the PCI index, implying significant development of precipitation concentration irregularities in these two stations. In summer, Gorgan station showed a strong and significant irregularity for the PCI index and in autumn, Tabriz and Zahedan (Babolsar) stations experienced a significant increasing (decreasing) trend in the PCI index. At the annual time scale, 50 % of stations experienced an increasing trend in the PCI index. Investigating the changes in the precipitation trend also revealed that in annual time scale, about 58 % of the stations had a decreasing trend. In winter, which is the rainiest season in Iran, about 64 % of stations experienced a decreasing trend in precipitation that caused an increasing trend in PCI index. Comparing the spatial distribution of PCI index within two 25 years sub-periods indicated that the PCI index of the second sub-period increased in the spring time scale that means irregularity of precipitation distribution has been increased. But in the other seasons any significant variations were not observed. Also in the annual time scale the PCI index increased in the second sub-period because of the increasing trend of precipitation.  相似文献