Shocks in multicomponent cylindrical and spherical Lorentzian plasmas     

S. Hussain  N. Akhtar  S. Mahmood 《Astrophysics and Space Science》2013,343(1):329-333

Nonlinear cylindrical and spherical ion acoustic shocks have been studied in unmagnetized dissipative non-Maxwellian electron-positron-ion (e-p-i) plasmas. Modified Korteweg-de Vries Burgers (mKdVB) has been derived by using reductive perturbation method. Two level finite difference scheme is used with the help of Runge Kutta method to simulate the mKdVB. It is noticed that positron concentration, spectral indices of electrons and positrons, kinematic viscosity of ions significantly modifies the strength of shocks in cylindrical and spherical geometries.  相似文献   

Screening Indian Mustard Genotypes for Phytoremediating Arsenic‐Contaminated Soils     

Mohd Kafeel Ahmad Ansari  Shahid Umar  Altaf Ahmad  Shahid Hussain Ansari  Muhammad Iqbal  Gary Owens  Hong‐Bo Shao 《洁净——土壤、空气、水》2013,41(3):313-314

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Noether gauge symmetry approach in f(R) gravity     

Ibrar Hussain  Mubasher Jamil  F. M. Mahomed 《Astrophysics and Space Science》2012,337(1):373-377

We discuss the f(R) gravity model in which the origin of dark energy is identified as a modification of gravity. The Noether symmetry with gauge term is investigated for the f(R) cosmological model. By utilization of the Noether Gauge Symmetry (NGS) approach, we obtain two exact forms f(R) for which such symmetries exist. Further it is shown that these forms of f(R) are stable.  相似文献   

Warm generalized cosmic Chaplygin gas inflation inspired by generalized dissipative coefficient     

Abdul Jawad  Shahzad Hussain 《Astrophysics and Space Science》2018,363(1):4

We examine the warm inflationary universe model in the presence of generalized cosmic Chaplygin gas and standard scalar field. We assume the generalized dissipative coefficient and corresponding weak and strong dissipative regimes. In this framework, we analyze the characteristics of inflationary dynamics under the slow-roll approximations. Under these approximations, we formulate the important inflationary parameters, such as scalar spectral index, scalar and tensor power spectrum, tensor-to-scalar ratio etc. It is interesting to note that our results for these inflationary parameters are well corroborated with the recent observational data like WMAP7, WMAP9 and Planck data.  相似文献   

Seismic based characterization of total organic content from the marine Sembar shale,Lower Indus Basin,Pakistan     

Omer Aziz  Tahir Hussain  Matee Ullah  Asher Samuel Bhatti  Aamir Ali 《Marine Geophysical Researches》2018,39(4):491-508

The exploration and production of unconventional resources has increased significantly over the past few years around the globe to fulfill growing energy demands. Hydrocarbon potential of these unconventional petroleum systems depends on the presence of significant organic matter; their thermal maturity and the quality of present hydrocarbons i.e. gas or oil shale. In this work, we present a workflow for estimating Total Organic Content (TOC) from seismic reflection data. To achieve the objective of this study, we have chosen a classic potential candidate for exploration of unconventional reserves, the shale of the Sembar Formation, Lower Indus Basin, Pakistan. Our method includes the estimation of TOC from the well data using the Passey’s ΔlogR and Schwarzkofp’s methods. From seismic data, maps of Relative Acoustic Impedance (RAI) are extracted at maximum and minimum TOC zones within the Sembar Formation. A geostatistical trend with good correlation coefficient (R²) for cross-plots between TOC and RAI at well locations is used for estimation of seismic based TOC at the reservoir scale. Our results suggest a good calibration of TOC values from seismic at well locations. The estimated TOC values range from 1 to 4% showing that the shale of the Sembar Formation lies in the range of good to excellent unconventional oil/gas play within the context of TOC. This methodology of source rock evaluation provides a spatial distribution of TOC at the reservoir scale as compared to the conventional distribution generated from samples collected over sparse wells. The approach presented in this work has wider applications for source rock evaluation in other similar petroliferous basins worldwide.  相似文献   

Analysis of earthquake-triggered failure mechanisms of slopes and sliding surfaces   总被引：1，自引：0，他引：1  

Jian Wang  Lingkan Yao  Arshad Hussain 《山地科学学报》2010,7(3):282-290

Earthquake-induced landslides along the Dujiangyan-Yingxiu highway after the Ms 8.0 Wenchuan earthquake in 2008 were investigated. It was found that: (1) slopes were shattered and damaged during the earthquake and open tension cracks formed on the tops of the slopes; (2) the upper parts of slopes collapsed and slid, while the lower parts remained basically intact, indicating that the upper parts of slopes would be damaged more heavily than the lower parts during an earthquake.  相似文献   

Effects of Irrigation and Drainage Modes on the Residual Characteristics of Heavy Metals in Soil          下载免费PDF全文

Zhenhua Zhao  Yunyun Zhang  Xiuming Lei  Liling Xia  Xin Jiang  Javid Hussain  Elchico Fawundu 《洁净——土壤、空气、水》2016,44(3):291-298

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Morpho‐Physiological Growth and Yield Responses of Two Contrasting Maize Cultivars to Cadmium Exposure          下载免费PDF全文

Shakeel Ahmad Anjum  Mohsin Tanveer  Saddam Hussain  Ehsan ullah  Longchang Wang  Imran Khan  Rana Abdul Samad  Shahbaz Atta Tung  Madiha Anam  Babar Shahzad 《洁净——土壤、空气、水》2016,44(1):29-36

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The first magnetic maps of a pre-main-sequence binary star system – HD 155555     

N. J. Dunstone  G. A. J. Hussain  A. Collier Cameron  S. C. Marsden  M. Jardine  H. C. Stempels  J. C. Ramirez Vlez  J.-F. Donati 《Monthly notices of the Royal Astronomical Society》2008,387(2):481-496

We present the first maps of the surface magnetic fields of a pre-main-sequence binary system. Spectropolarimetric observations of the young, 18 Myr, HD 155555 (V824 Ara, G5IV+K0IV) system were obtained at the Anglo-Australian Telescope in 2004 and 2007. Both data sets are analysed using a new binary Zeeman–Doppler imaging (ZDI) code. This allows us to simultaneously model the contribution of each component to the observed circularly polarized spectra. Stellar brightness maps are also produced for HD 155555 and compared to previous Doppler images.
Our radial magnetic maps reveal a complex surface magnetic topology with mixed polarities at all latitudes. We find rings of azimuthal field on both stars, most of which are found to be non-axisymmetric with the stellar rotational axis. We also examine the field strength and the relative fraction of magnetic energy stored in the radial and azimuthal field components at both epochs. A marked weakening of the field strength of the secondary star is observed between the 2004 and 2007 epochs. This is accompanied by an apparent shift in the location of magnetic energy from the azimuthal to radial field. We suggest that this could be indicative of a magnetic activity cycle. We use the radial magnetic maps to extrapolate the coronal field (by assuming a potential field) for each star individually – at present ignoring any possible interaction. The secondary star is found to exhibit an extreme tilt (≈75°) of its large-scale magnetic field to that of its rotation axis for both epochs. The field complexity that is apparent in the surface maps persists out to a significant fraction of the binary separation. Any interaction between the fields of the two stars is therefore likely to be complex also. Modelling this would require a full binary field extrapolation.  相似文献   

Reservoir characterization of basal sand zone of lower Goru Formation by petrophysical studies of geophysical logs     

Mureed Hussain  Nisar Ahmed  Wang Yan Chun  Perveiz Khalid  Azhar Mahmood  Sajid Rashid Ahmad  Umair Rasool 《Journal of the Geological Society of India》2017,89(3):331-338

The lower Indus basin is one of the largest hydrocarbon producing sedimentary basins in Pakistan. It is characterized by the presence of many hydrocarbon-bearing fields including clastic and carbonates proven reservoirs from the Cretaceous to the Eocene age. This study has been carried out in the Sanghar oil field to evaluate the hydrocarbon prospects of basal sand zone of lower Goru Formation of Cretaceous by using complete suite of geophysical logs of different wells. The analytical formation evaluation by using petrophysical studies and neutron-density crossplots unveils that litho-facies mainly comprising of sandstone. The hydrocarbons potentialities of the formation zone have been characterized through various isoparameteric maps such as gross reservoir and net pay thickness, net-to-gross ratio, total and effective porosity, shaliness, and water and hydrocarbons saturation. The evaluated petrophysical studies show that the reservoir has net pay zone of thickness range 5 to 10 m, net-togross ratio range of 0.17 to 0.75, effective porosity range of 07 to 12 %, shaliness range of 27 to 40 % and hydrocarbon saturation range of 12 to 31 %. However, in the net pay zone hydrocarbon saturation reaches up to 95%. The isoparametric charts of petrophysically derived parameters reveal the aerial distribution of hydrocarbons accumulation in basal sand unit of the lower Goru Formation which may be helpful for further exploration.  相似文献