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11.
In this work, we have considered the DBI-essence dark energy model in FRW Universe. We have found the exact solutions of potential,
warped brane tension and DBI scalar field. We also calculate the statefinder parameters for our model that make it distinguishable
among numerous dark energy models. Moreover, we establish correspondence between DBI-essence and modified Chaplygin gas (MCG)
and hence reconstruct the potential and warped brane tension. By this reconstruction, we observe that DBI scalar field and
potential increase and warped brane tension decreases during evolution of the Universe. Finally, we investigate the validity
of the generalized second law (GSL) of thermodynamics in the presence of DBI-essence and modified Chaplygin gas. It is observed
that the GSL breaks down for DBI-essence model but GSL always satisfied for MCG model. 相似文献
12.
D. Dwivedee B. Nayak M. Jamil L. P. Singh R. Myrzakulov 《Journal of Astrophysics and Astronomy》2014,35(1):97-106
In this work, we study the evolution of primordial black holes within the context of loop quantum cosmology. First we calculate the scale factor and energy density of the Universe for different cosmic era and then taking these as inputs, we study evolution of primordial black holes. From our estimation it is found that accretion of radiation does not affect evolution of primordial black holes in loop quantum cosmology. We also conclude that due to slow variation of scale factor, the upper bound on initial mass fraction of presently evaporating PBHs are much greater in loop quantum cosmology than the standard case. 相似文献
13.
Muhammad Riaz Mumtaz Khan Shafaqat Ali Muhammad Daud Khan Rehan Ahmad Muhammad Jamil Khan Muhammad Rizwan 《Arabian Journal of Geosciences》2018,11(23):752
Biochar has been considered a safe soil additive to enhance soil fertility and agronomic traits of different crops. This study was conducted to explore the impacts of sugarcane waste straw biochar on soil characteristics and some agronomic traits of okra. The experiment was carried out with four treatments, i.e., control, sugarcane waste straw biochar (10 ton ha?1), farmyard manure (FYM, 10 ton ha?1), and chemical fertilizers (NPK; 120:100:80 kg ha?1) having three replications of each treatment. Soil samples were tested for texture, bulk density, particle density, pH, electrical conductivity (EC), organic matter content, nitrate nitrogen (NO3-N), and extractable-P. The sugarcane waste straw biochar was characterized for plant major nutrient elements. The impact of various treatments was observed on soils and agronomic traits of okra like plant height, fruit size, fruit length, and yield of okra. Results revealed that sugarcane waste straw biochar expressed higher EC value and noticeable amounts of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and magnesium (Mg). The sugarcane waste straw biochar, in comparison with FYM and NPK, significantly improved the NO3-N, extractable-P, OM and EC of the calcareous soil, and reduced the soil bulk density. Furthermore, plant growth and yield parameters were significantly improved under biochar application over the control, FYM and NPK. Overall, sugarcane waste straw biochar proved to be a good alternative to conventional organic and inorganic fertilizers under calcareous soil conditions. 相似文献
14.
Exploitation of Landsat data for snow zonation mapping in the Hindukush,Karakoram and Himalaya (HKH) region of Pakistan 总被引：1，自引：0，他引：1
Mohsin Jamil Butt 《水文科学杂志》2013,58(5):1088-1096
Abstract In the Hindukush, Karakoram and Himalaya (HKH) region of Pakistan, many glaciological variables are still not known due to the remoteness and harsh weather conditions of the area. A remote sensing technique is therefore applied to map the snow zonation in the HKH region. Landsat 7 ETM+ data for the year 2003 are used in this study. Image classification and image processing techniques are applied to map, for the first time, the major snow zones in the HKH region. Six classes are identified: the results show that the area covered by the highest-altitude snow (Snow I), lower-altitude snow (Snow II), bare ice, debris-covered ice, wet snow and shadow is 21 529.42, 22 472.58, 8696.41, 8038.75, 12 159.37 and 7322.30 km2, respectively. The study also indicates that the equilibrium line altitude (ELA) lies between 5000 and 5500 m above sea level, with an accumulation area ratio (AAR) of 0.60. Citation Butt, M.J., 2013. Exploitation of Landsat data for snow zonation mapping in the Hindukush, Karakoram and Himalaya (HKH) region of Pakistan. Hydrological Sciences Journal, 58 (5), 1088–1096. 相似文献
15.
Adnan Aslam Mubasher Jamil Davood Momeni Ratbay Myrzakulov Muneer Ahmad Rashid Muhammad Raza 《Astrophysics and Space Science》2013,348(2):533-540
In literature usual point like symmetries of the Lagrangian have been introduced to study the symmetries and the structure of the fields. This kind of Noether symmetry is a subclass of a more general family of symmetries, called Noether gauge symmetries (NGS). Motivated by this mathematical tool, in this paper, we study the generalized Noether symmetry of quintom model of dark energy, which is a two component fluid model with quintessence and phantom scalar fields. Our model is a generalization of the Noether symmetries of a single and multiple components which have been investigated in detail before. We found the general form of the quintom potential in which the whole dynamical system has a point like symmetry. We investigated different possible solutions of the system for diverse family of gauge function. Specially, we discovered two family of potentials, one corresponds to a free quintessence (phantom) and the second is in the form of quadratic interaction between two components. These two families of potential functions are proposed from the symmetry point of view, but in the quintom models they are used as phenomenological models without clear mathematical justification. From integrability point of view, we found two forms of the scale factor: one is power law and second is de-Sitter. Some cosmological implications of the solutions have been investigated. 相似文献
16.
Kazuharu Bamba Mubasher Jamil D. Momeni Ratbay Myrzakulov 《Astrophysics and Space Science》2013,344(1):259-267
We study the generalized second law (GSL) of thermodynamics in f(T) cosmology, where T is the torsion scalar in teleparallelism. We consider the universe as a closed bounded system filled with n component fluids in the thermal equilibrium with the cosmological boundary. We use two different cosmic horizons: the future event horizon and the apparent horizon. We show the conditions under which the GSL will be valid in specific scenarios of the quintessence and the phantom energy dominated eras. Further we associate two different entropies with the cosmological horizons: with a logarithmic correction term and a power-law correction term. We also find the conditions for the GSL to be satisfied or violated by imposing constraints on model parameters. 相似文献
17.
We present models, in which phantom energy interacts with two different types of dark energies including variable modified
Chaplygin gas (VMCG) and new modified Chaplygin gas (NMCG). We then construct potentials for these cases. It has been shown
that the potential of the phantom field decreases from a higher value with the evolution of the Universe. 相似文献
18.
Landslide dam and subsequent dam-break flood estimation using HEC-RAS model in Northern Pakistan 总被引：1，自引：0，他引：1
On the morning of January 4, 2010, a massive landslide swept the Attabad and Sarat villages into the Hunza River. The debris from the landslide blocked the low-lying river, creating a barrier lake in the area and poses a major threat to the villages located downstream. The aim of the current study was to evaluate the environmental advantages and disadvantages created by the formation of the artificial lake. For this purpose, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were used to create the contours and triangulated irregular network (TIN) of the region. Data from ??Google Earth?? image on March 19, 2010 were used as the reference and to determine the river bed elevation of the study area. Landsat satellite data of Enhanced Thematic Mapper Plus (ETM+) sensor on January 10, March 15, April 24 and May 2, 2010, were used for constructing the Geographic Information System (GIS) layers of the river banks, land use area, overbank flow area and water area estimation. Our results show that the area covered by the water in the lake has increased from 1.28?km2 on January 10, 2010 to 6.25?km2 on May 2, 2010. The total upstream urban area affected by the river blockage is 13.99?km2. We also applied the Hydrologic Engineering Center River Analysis System (HEC-RAS) model to estimate the potential catastrophes due to dam burst for different peak outflow scenarios with conclusions and recommendations. 相似文献
19.
中国对虾肌动球蛋白变性后ATPase活性的研究 总被引：1，自引：0，他引：1
在中国对虾肌动球蛋白（Ａｏｔｏｍｙｏｓｉｎ）经冷冻变性和热变性后，对Ｃａ２＋－ＡＴＰａｓｅ、Ｍｇ２＋－ＡＴＰａｓｅ活性及蛋白质溶解度进行了研究。冷冻变性之后，肌动球蛋白Ｃａ２＋－ＡＴＰａｓｅ活性呈逐渐下降趋势，一般贮藏温度越低，活性降低越快。热变性之后，肌动球蛋白Ｃａ２＋或Ｍｇ２＋－ＡＴＰａｓｅ活性都随温度升高而下降，但肌动球蛋白Ｃａ２＋或Ｍｇ２＋－ＡＴＰａｓｅ活性在３５℃有一急剧下降的拐点，并分别在４５℃、４０℃附近低到０。由于蛋白质的变性，其溶解度也降低 相似文献
20.
Farook Rahaman Mubasher Jamil Kaushik Chakraborty 《Astrophysics and Space Science》2011,331(1):191-197
Motivated by earlier studies (Tiwari et al. in Astrophys. Space Sci. 182:105, 1984; Herrera and Varela in Phys. Lett. 189:11, 1994), we model electron as a spherically symmetric charged perfect fluid distribution of matter. The existing model is extended
assuming a matter source that is characterized by quadratic equation of state in the context of general theory of relativity.
For the suitable choices of the parameters, our charged fluid models almost satisfy the physical properties of electron. 相似文献