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   

An interacting scenario for dark energy in a Bianchi type-I universe     

Hassan Amirhashchi  Syed Nasrullah Ali Qazi  Hishamuddin Zainuddin 《中国天文和天体物理学报》2014,(11)

We study the interaction between dark energy(DE) and dark matter in the scope of anisotropic Bianchi type-I space-time. First we derive the general form of the DE equation of state(EoS) parameter in both non-interacting and interacting cases and then we examine its future by applying a hyperbolic scale factor. It is shown that in the non-interacting case, depending on the value of the anisotropy parameter K,the DE EoS parameter varies from phantom to quintessence whereas in the interacting case the EoS parameter varies in the quintessence region. However, in both cases, the DE EoS parameter ωdeultimately(i.e. at z =-1) tends to the cosmological constant(ωde=-1). Moreover, we fix the cosmological bound on the anisotropy parameter K by using recent observational data about the Hubble parameter.  相似文献   

Plasticity model for inherently anisotropic behaviour of sands     

Jamshid Ghaboussi  Hassan Monen 《国际地质力学数值与分析法杂志》1984,8(1):1-17

Most deposited sands exhibit anisotropic behaviour. A plasticity model has been proposed with the capacity for simulating such anisotropic behaviour. The proposed model contains a number of coefficients of anisotropy. Methodology for determination of the coefficients of anisotropy has been discussed. Using experimental data, the coefficients of anisotropy have been determined for a number of well-known sands. Stress-dilatancy has been modelled by using the ‘normalized work’ and it has been shown that the normalized work is independent of inherent anisotropy. Finally, some reasonably close comparisons between experimental results and model simulations have been reported.  相似文献   

Relativistic compact anisotropic charged stellar models with Chaplygin equation of state     

Piyali Bhar  Mohammad Hassan Murad 《Astrophysics and Space Science》2016,361(10):334

  相似文献   

Incorporation of silica into the goethite structure: a microscopic and spectroscopic study     

Abdullah Musa Ali  Eswaran Padmanabhan  Hassan Baioumy 《中国地球化学学报》2018,37(6):911-921

Quartz and iron (hydr)oxide are reactive surface phases that are often associated with one another in soils and sediments. Despite the several studies on the coating of quartz with iron oxides, the reactivity of dissolved species (Si) leached from quartz with iron (hydr)oxides has received limited attention. In this study, goethite synthesized on quartz substrates were characterized using field emission scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy, and Fourier-transform infrared (FT-IR) spectroscopy. The SEM characterization revealed that bundles of thin parallel aligned goethite rods were formed at pH?>?10, while large pseudohexagonal crystals of twinned goethite needles were synthesized at pH?≤?10 after dehydration and hydration in the alkaline media. TEM analysis showed expanded and distorted lattice spacing of the crystal structure of iron (hydr)oxide due to silica incorporation. The characterization showed that silica increased the crystallite size of the goethite and transformed its acicular texture to a larger, twinned needle structure. FT-IR and XRD analyses revealed band shifts in crystal bonds as well as new bond formations, which indicate the presence of changes in the chemical environment of Fe–O and Si–O bonds. Thus, the presence of sorbed silicates modifies the crystal and lattice structure of goethite.  相似文献   

U–Pb geochronology,Sr–Nd isotopic compositions,geochemistry and petrogenesis of Shah Soltan Ali granitoids,Birjand, Eastern Iran     

Mohammad Hassan Karimpour  Azadeh Malekzadeh Shafaroudi  José Francisco Santos  Ryan Mathur  Sara Ribeiro 《Chemie der Erde / Geochemistry》2018,78(3):299-313

The Shah Soltan Ali area (SSA) is located in the eastern part of the Lut Block metallogenic province. In this area different types of sub-volcanic intrusions including diorite porphyry, monzonite porphyry and monzodiorite porphyry have intruded into basaltic and andesitic rocks. Zircon U–Pb dating and field observations indicate that intermediate to mafic volcanic rocks (38.9 Ma) are older than subvolcanic units (38.3 Ma). The subvolcanic intrusions show high-K calc-alkaline to shoshonitic affinity and are metaluminous. Based on mineralogy, high values of magnetic susceptibility [(634 to 3208) × 10^?5 SI], and low initial ⁸⁷Sr/⁸⁶Sr ratios, they are classified as belonging to the magnetite-series of oxidant I-type granitoids and are characterized by an enrichment in LREEs relative to HREEs, with negative Nb, Ti, Zr and Eu anomalies. These granitoids are related to volcanic arc (VAG) and were generated in an active continental margin. Low initial ⁸⁷Sr/⁸⁶Sr ratios (0.7043 to 0.7052) and positive εNd values (+1.48 to +3.82) indicate that the parental magma was derived from mantle wedge. Parental magma was probably formed by low degree of partial melting and metasomatized by slab derived fluids. Then assimilation and fractional crystallization processes (AFC) produced the SSA rocks. This magma during the ascent was contaminated with the crustal material.All data suggest that Middle-Late Eocene epoch magmatism in the SSA area, occurred during subduction of Neo-Tethys Ocean in east of Iran (between Afghan and Lut Blocks).  相似文献   

A Risk-Based Technique to Analyze Flyrock Results Through Rock Engineering System     

Mahdi Hasanipanah  Danial Jahed Armaghani  Hassan Bakhshandeh Amnieh  Mohammadreza Koopialipoor  Hossein Arab 《Geotechnical and Geological Engineering》2018,36(4):2247-2260

Flyrock is an adverse effect produced by blasting in open-pit mines and tunneling projects. So, it seems that the precise estimations and risk level assessment of flyrock are essential in minimizing environmental effects induced by blasting. The first aim of this research is to model the risk level associated with flyrock through rock engineering systems (RES) methodology. In this regard, 62 blasting were investigated in Ulu Tiram quarry, Malaysia, and the most effective parameters of flyrock were measured. Using the most influential parameters on flyrock, the overall risk of flyrock was obtained as 32.95 which is considered as low to medium degree of vulnerability. Moreover, the second aim of this research is to estimate flyrock based on RES and multiple linear regression (MLR). To evaluate performance prediction of the models, some statistical criteria such as coefficient of determination (R²) were computed. Comparing the values predicted by the models demonstrated that the RES has more suitable performance than MLR for predicting the flyrock and it could be introduced as a powerful technique in this field.  相似文献   

Calibration of categorical simulations by evolutionary gradual deformation method     

Hassan Rezaee  Denis Marcotte 《Computational Geosciences》2018,22(2):587-605

Methods to simulate facies (or categorical) fields are numerous. However, calibration of simulated facies fields to large-scale or dynamic data still remains an important challenge due to the discrete nature of the fields, the non-linearity of the response with respect to the facies fields, and the non-derivability of the objective function used in calibration. A new gradual deformation method (GDM) is presented and tested for the calibration of facies realizations obtained by patch-multipoint simulation (MPS). The proposed method borrows ideas from pluriGaussian simulation, evolutionary algorithms, and GDM. Various test cases are considered: proportion maps, section of seismic amplitudes, inlet to outlet travel time along the shortest path, and water-cut curves obtained with a flow simulator. Both conditional/unconditional MPS simulations and 2D/3D problems are considered. In all studied test cases, the new GDM approach has provided excellent calibration to the target variables. The method is general as it can be used in conjunction with any facies simulator.  相似文献   

Assessment of agricultural groundwater users in Iran: a cultural environmental bias     

Saeid Salehi  Mohammad Chizari  Hassan Sadighi  Masoud Bijani 《Hydrogeology Journal》2018,26(1):285-295

Many environmental problems are rooted in human behavior. This study aimed to explore the causal effect of cultural environmental bias on ‘sustainable behavior’ among agricultural groundwater users in Fars province, Iran, according to Klockner’s comprehensive model. A survey-based research project was conducted to gathering data on the paradigm of environmental psychology. The sample included agricultural groundwater users (n = 296) who were selected at random within a structured sampling regime involving study areas that represent three (higher, medium and lower) bounds of the agricultural-groundwater-vulnerability spectrum. Results showed that the “environment as ductile (EnAD)” variable was a strong determinant of sustainable behavior as it related to groundwater use, and that EnAE had the highest causal effect on the behavior of agricultural groundwater users. The adjusted model explained 41% variance of “groundwater sustainable behavior”. Based on the results, the groundwater sustainable behaviors of agricultural groundwater users were found to be affected by personal and subjective norm variables and that they are influenced by casual effects of the “environment as ductile (EnAD)” variable. The conclusions reflect the Fars agricultural groundwater users’ attitude or worldview on groundwater as an unrecoverable resource; thus, it is necessary that scientific disciplines like hydrogeology and psycho-sociology be considered together in a comprehensive approach for every groundwater study.  相似文献   

The use of connectivity clusters in stochastic modelling of highly heterogeneous porous media     

Mohamed A. Awad  Ahmed E. Hassan  Hesham M. Bekhit 《Arabian Journal of Geosciences》2018,11(5):98

Stochastic geostatistical techniques are essential tools for groundwater flow and transport modelling in highly heterogeneous media. Typically, these techniques require massive numbers of realizations to accurately simulate the high variability and account for the uncertainty. These massive numbers of realizations imposed several constraints on the stochastic techniques (e.g. increasing the computational effort, limiting the domain size, grid resolution, time step and convergence issues). Understanding the connectivity of the subsurface layers gives an opportunity to overcome these constraints. This research presents a sampling framework to reduce the number of the required Monte Carlo realizations utilizing the connectivity properties of the hydraulic conductivity distributions in a three-dimensional domain. Different geostatistical distributions were tested in this study including exponential distribution with the Turning Bands (TBM) algorithm and spherical distribution using Sequential Gaussian Simulation (SGSIM). It is found that the total connected fraction of the largest clusters and its tortuosity are highly correlated with the percentage of mass arrival and the first arrival quantiles at different control planes. Applying different sampling techniques together with several indicators suggested that a compact sample representing only 10% of the total number of realizations can be used to produce results that are close to the results of the full set of realizations. Also, the proposed sampling techniques specially utilizing the low conductivity clustering show very promising results in terms of matching the full range of realizations. Finally, the size of selected clusters relative to domain size significantly affects transport characteristics and the connectivity indicators.  相似文献