A holographic reconstruction of the modified f(R) Horava-Lifshitz gravity with scale factor in power-law form     

Abdul Jawad  Surajit Chattopadhyay  Antonio Pasqua 《Astrophysics and Space Science》2013,346(1):273-278

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Correspondence between f(G) gravity and holographic dark energy via power-law solution     

Abdul Jawad  Antonio Pasqua  Surajit Chattopadhyay 《Astrophysics and Space Science》2013,344(2):489-494

In this paper, we discuss cosmological application of holographic Dark Energy (HDE) in the framework of f(G) modified gravity. For this purpose, we construct f(G) model with the inclusion of HDE and a well-known power law form of the scale factor a(t). The reconstructed f(G) is found to satisfy a sufficient condition for a realistic modified gravity model. We find quintessence behavior of effective equation of state (EoS) parameter ω _DE through energy conditions in this context. Moreover, we observe that the squared speed of sound $v_{s}^{2}$ remains negative, which indicates the instability of HDE f(G) model.  相似文献   

Assessment of Trace Metal Contamination of Drinking Water in the Pearl Valley,Azad Jammu and Kashmir     

Saboor Javaid  Syed Ghulam Sarwar Shah  Abdul Jabbar Chaudhary  Mohammad Haleem Khan 《洁净——土壤、空气、水》2008,36(2):216-221

The aim of this study was to assess trace metal contamination of drinking water in the Pearl Valley, Azad Jammu and Kashmir (Pakistan). The objectives were to determine physical properties and the dissolved concentration of five trace metals, i. e., lead, copper, nickel, zinc, and manganese, in drinking water samples collected from various sites of municipal water supply, natural water springs and wells in the valley. Concentrations of the metals in the water samples were determined by flame atomic absorption spectrometry. Results showed physical parameters, i. e., appearance, taste and odor within acceptable limits and pH was between 5.5 and 7.0. The observed concentrations of the metals varied between sources of water samples and between sampling sites. Maximum dissolved concentration observed was 4.7 mg/L for Pb and Mn, 4.6 mg/L for Zn, 2.9 mg/L for Ni and 2.8 mg/L for Cu. The observed concentrations of the metals were compared with the World Health Organization's guideline values for drinking water. Overall, the quality of water samples taken from the water springs at Mutyal Mara and Bonjosa was good; however, the water quality was unsuitable for drinking in Kiraki, Kharick, and Pothi Bala localities particularly. Finally, the authors discuss possible causes for increased concentrations of the trace metals in drinking water in the study area.  相似文献   

利用NOAA-AVHRR数据分析1982-2001年间中国植被的动态变化(英文)   总被引：1，自引：0，他引：1  

HABIB Aziz Salim  陈晓玲  龚健雅  王海燕  张俐 《地球空间信息科学学报》2009,12(2):146-153

The authors derived the normalized difference vegetation index (NDVI) from the NOAA/AVHRR Land dataset, at a spatial resolution of 8km and 15-day intervals, to investigate the vegetation variations in China during the period from 1982 to 2001. Then, GIS is used to examine the relationship between precipitation and the Normalized Difference Vegetation Index (NDVI) in China, and the value of NDVI is taken as a tool for drought monitoring. The results showed that in the study period, China’s vegetation cover h...  相似文献   

中国夏季气候对植被覆盖的影响:1982～2001(英文)     

HABIB Aziz Salim  陈晓玲  龚健雅  张力 《地球空间信息科学学报》2009,(1)

In this paper, we apply lagged correlation analysis to study the effects of vegetation cover on the summer climate in different zones of China, using NOAA/AVHRR normalized difference vegetation index (NDVI) data during the time period from 1982 to 2001 and climate data of 365 meteorological stations across China (precipitation from 1982 to 2001 and temperature from 1982 to 1998). The results show that there are positive correlations between spring NDVI and summer climate (temperature and precipitation) in m...  相似文献   

The construction of a third-order secular analytical J-S-U-N theory by the Hori-Lie technique     

Abdel Aziz Bakry  Osman M. Kamel  Salwa M. Waziry 《Earth, Moon, and Planets》1993,63(1):29-66

We expand both parts, the principal and indirect, of the Hamiltonian function up to the third order in the masses for the four major planets Jupiter-Saturn-Uranus-Neptune. Accordingly we write down the secular terms ofF ₁,F ₂,F ₃ and the critical terms ofF ₁,F ₂ in terms of the canonical variables of H. Poincaré neglecting powers higher than the second inH, K, P, Q.  相似文献   

Evidences of Holocene transgression on Domingos Petrolini Swamp, southern coastal plain, Rio Grande do Sul, Brazil     

Soraia G.Bauermann  Paulo C.P.Neves  Marleni Marques-Toigo  Abdul R.Ashraf 《东北亚地学研究》2005,(Z1)

The Domingos Petrolini Swamp, located on the Southern Coastal Plain of Rio Grande do Sul, near the town of Rio Grande, constitutes an ample holocene lagoonal deposit. Events related to the holocene transgression and their diverse phases of glacial-eustatic ocillations were found through palynological analysis. Bases on these palynological data, four distinct phases to the paleoenvironmental evolution of the ecosystem were identified. It has also shown a transgressive restricted marine sequence on the base , which suggests the existence of a coastal brackish lagoon or a marisme type of environment. Later, there was a gradation for continentality conditions along with a scarce pollinical record. The third phase is characterized by the presence of marine components and halophyte vegetation, showing another transgressive event in that place. Lastly, the end of direct marine influence over the swamp was recorded and also the vegetation development as it appears these days.  相似文献   

Jewish settlement and its economic impact on the West Bank, 1967–1987     

Hassan Abdul Kadir Saleh Prof. 《GeoJournal》1990,21(4):337-348

This paper focuses on the process of Jewish settlement in the West Bank and its economic consequences in the period from 1967 to the outbreak of the Intifada late in 1987. It attempts to show that this process is the practical application of Israeli objectives which are based on expansion and occupation of neighbouring Arab lands, facilitated by the fashioning of a dual or bifurcate economy there.After the war of June 1967, Israeli occupation authorities started to draw up plans with a view to settling Jews in the West Bank. There has been an increase in the numbers of settlements and settlers, estimated at 122 and 52,000 respectively in 1987. The pattern of settlement distribution is randomly dispersed, although it is concentrated in a region located to the NW of Jerusalem. The settlement began in the Jordan valley and extended gradually westward in the highlands.Jewish settlement has affected economic development of the West Bank, where there were many constraints on Arab agriculture and industry. Inequality is evident between settlers and Palestinians in an economy that has been structurally bifurcated: although settlers represent about 3% of total population of the West Bank, their economic activity constitutes at least 35% of the GDP of the West Bank.  相似文献   

Kernel Principal Component Analysis for Efficient,Differentiable Parameterization of Multipoint Geostatistics   总被引：6，自引：5，他引：1  

Pallav Sarma  Louis J. Durlofsky  Khalid Aziz 《Mathematical Geosciences》2008,40(1):3-32

This paper describes a novel approach for creating an efficient, general, and differentiable parameterization of large-scale non-Gaussian, non-stationary random fields (represented by multipoint geostatistics) that is capable of reproducing complex geological structures such as channels. Such parameterizations are appropriate for use with gradient-based algorithms applied to, for example, history-matching or uncertainty propagation. It is known that the standard Karhunen–Loeve (K–L) expansion, also called linear principal component analysis or PCA, can be used as a differentiable parameterization of input random fields defining the geological model. The standard K–L model is, however, limited in two respects. It requires an eigen-decomposition of the covariance matrix of the random field, which is prohibitively expensive for large models. In addition, it preserves only the two-point statistics of a random field, which is insufficient for reproducing complex structures. In this work, kernel PCA is applied to address the limitations associated with the standard K–L expansion. Although widely used in machine learning applications, it does not appear to have found any application for geological model parameterization. With kernel PCA, an eigen-decomposition of a small matrix called the kernel matrix is performed instead of the full covariance matrix. The method is much more efficient than the standard K–L procedure. Through use of higher order polynomial kernels, which implicitly define a high-dimensionality feature space, kernel PCA further enables the preservation of high-order statistics of the random field, instead of just two-point statistics as in the K–L method. The kernel PCA eigen-decomposition proceeds using a set of realizations created by geostatistical simulation (honoring two-point or multipoint statistics) rather than the analytical covariance function. We demonstrate that kernel PCA is capable of generating differentiable parameterizations that reproduce the essential features of complex geological structures represented by multipoint geostatistics. The kernel PCA representation is then applied to history match a water flooding problem. This example demonstrates that kernel PCA can be used with gradient-based history matching to provide models that match production history while maintaining multipoint geostatistics consistent with the underlying training image.  相似文献   

Aqueous Surfactant Washing of Residual Oil Contamination from Sandy Soil   总被引：2，自引：0，他引：2  

Carolina C. Ang  Abdul S. Abdul 《Ground Water Monitoring & Remediation》1991,11(2):121-127

A laboratory study was conducted to determine the efficiency of different aqueous concentrations of an alcohol ethoxylate surfactant in washing residual levels of an oil [automatic transmission fluid (ATF)] from sandy soil. Five glass columns packed with the soil were prepared in a manner that simulated conditions leading to residual saturation in an actual oil leak. Each of four columns was washed continuously with 28 pore volumes of solution by pumping either 0.0 percent (water), 0.5 percent, 1.0 percent, or 2.0 percent aqueous surfactant solutions through the columns. The fifth column was washed intermittently with 28 pore volumes of a 1.0 percent surfactant solution. Water washed only 25.5 percent of the ATF from the column soil, while the 0.5 percent, 1 percent, and 2 percent surfactant solutions washed 55 percent, 60 percent, and 72.8 percent of the ATF, respectively. The distribution of the ATF remaining in the column after washing showed that the ATF removed by water was mainly from the outlet side of the column, while the ATF removed by the 2.0 percent surfactant solution was mainly from the inlet side of the column. This observation indicated that different mechanisms were involved; namely, the displacement of oil through the soil-pore space, the dispersion of oil due to reduced surface tension, and the solubilization of oil by surfactant micelles. In the case of water, the displacement of oil was the main washing mechanism, while all three mechanisms were operative during surfactant washing. ATF dispersion and solubilization were improved at higher surfactant concentrations. The column that was washed intermittently to pulse ATF from dead end pores did not show a significant improvement over the column that was continuously washed with the same 1.0 percent surfactant solution. The results show promising potential for application in the field and will be further investigated in a two-dimensional model aquifer.  相似文献