Orbital evolution dynamics of two satellites in encounter phase using multiple scales expansion     

S. E. Abd El-Bar 《Astrophysics and Space Science》2014,350(1):155-168

An approximate solution of the encounter problem of two small satellites describing initially elliptical orbits around a massive oblate primary is obtained. The equations of motion of the center of mass of the two masses are developed in the most general form without any restrictions on the orbital elements. The method of multiple scales which seeks a solution whose behavior depends on several time scales is used. To overcome the singularity the equations of motion are transformed to the Struble variables. An analytical second order theory of the evolution dynamics is obtained. A MATHEMATICA program is constructed. The evolution dynamics of the orbital parameters between the perturbed and the unperturbed cases are plotted. The effect of changing eccentricity and changing inclination on the orbital parameters are highlighted.  相似文献   

Remote Sensing Inversion for Simulation of Soil Salinization Based on Hyperspectral Data and Ground Analysis in Yinchuan,China   总被引：2，自引：0，他引：2  

Wu  Dan  Jia  Keli  Zhang  Xiaodong  Zhang  Junhua  Abd El-Hamid  Hazem T. 《Natural Resources Research》2021,30(6):4641-4656

The Pingluo area, as an experimental study area in Yinchuan, has been subjected to major environmental degradation due to soil salinization problems. Soil salinization is one of the main problems of land degradation in arid and semiarid regions. In the present study, remote sensing was integrated with mathematical modeling to evaluate soil salinization adequately. To detect soil salinization, soil water content and electrical conductivity of soil samples were analyzed. The reflectance of soil samples was measured using a spectrometer (SR-3500) with 1024 bands. Indices of soil salinity, vegetation and drought were analyzed using Landsat images over the study area. Based on Landsat images, physicochemical analysis, reflectance of sensitive bands for soil salinization and environmental indices, canopy response salinity index (CRSI), perpendicular drought index (PDI) and enhanced normalized difference vegetation index (ENDVI), a new model was established for simulation and prediction of soil salinization in the study area. Correlation analyses and multiple regression methods were used to construct an accurate model. The results showed that green, blue and near-infrared light was significantly correlated with soil salinity and that the spectral parameters improved this correlation significantly. Therefore, the model was more effective when combining spectral parameters with sensitive bands with modeling. After mathematical transformation of soil reflectance, the correlations of bands sensitive to soil salinization were 0.739 and 0.7 for electrical conductivity and water content, respectively. After transformation of vegetation reflectance, the correlation coefficient of soil salinity became 0.577. After inversion of the model based on soil hyperspectral and water content, the significance became 0.871 and 0.726, respectively, which can be used to predict soil salinity and water content. The spectral soil salinity model had a coefficient of 0.739 for soil salinity prediction. Among the salinity indices, the CRSI was selected as the most significant, with R² of 0.571, whereas the R² for PDI reached only 0.484. Among the vegetation indices, the ENDVI had the highest response to soil salinity, with R² of 0.577. After scale conversion, the correlation percentages between CRSI and measured soil salinity and between ENDVI and measured soil salinity increased to 16.2% and 8.5%, respectively. Following the correlation between PDI and soil water content, the percentage of correlation increased to 11.6%. The integration of hyperspectral remote sensing, ground methods and an inversion method for salinity is a very important and effective technique for rapid and nondestructive monitoring of soil salinization.

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Generation of a stochastic precipitation model for the tropical climate     

Ng  Jing Lin  Abd Aziz  Samsuzana  Huang  Yuk Feng  Wayayok  Aimrun  Rowshon  MK 《Theoretical and Applied Climatology》2018,133(1-2):489-509

Theoretical and Applied Climatology - A tropical country like Malaysia is characterized by intense localized precipitation with temperatures remaining relatively constant throughout the year. A...  相似文献   

Makran ophiolitic basalts (SE Iran) record Late Cretaceous Neotethys plume-ridge interaction     

Rasoul Esmaeili  Mohammad Ebrahimi  Ji’En Zhang  Zhiyong Zhang  Yasser Abd El-Rahman 《International Geology Review》2020,62(13-14):1677-1697

ABSTRACT

The Makran complex in southeast Iran provides a spectacular subduction-related accretionary complex to understand the mechanism of oceanic accretion and the evolution of subduction zones. In this paper, we present new major and trace element data as well as isotopic compositions of mafic volcanic blocks from the Makran ophiolitic mélange complex (OMC). Our aim is to assess the genesis of these rocks and discuss their implications on the evolution of Neotethys Ocean. These volcanic blocks are composed mainly of basalts with minor trachytes. The Makran lavas are occasionally interlayered with tuff layers. Zircons from these tuffs give U-Pb ages of 95 Ma, which is well in accordance with the reposted microfossil data for the interlayered pelagic limestones with pillow lavas. Makran basalts can be geochemically subdivided into four groups; normal to transitional MORB, enriched-MORB, Plume-type MORB and alkaline (-OIB-like) basalts. The OIB-like pillow lavas are represented by high values of Th/Tb (6.3–7.4) which are higher than other basalts (group 1 = 0.3–0.8; groups 2 = 0.7–1.6; group 3 = 1.58–1.36).¹⁴³Nd/¹⁴⁴Nd_(t) ratios for basalts ranges from 0.51247 to 0.51292, whereas ⁸⁷Sr/⁸⁶Sr_(t) isotopic composition of the OMC lavas varies from 0.704433 to 0.709466. The Pb isotopic composition of the lavas are quite high, ranging from 15.49–15.66 for ²⁰⁷Pb/²⁰⁴Pb_(t), 18.09–19.12 for ²⁰⁶Pb/²⁰⁴Pb_(t) and 37.80–39.23 for ²⁰⁸Pb/²⁰⁴Pb_(t). The chemistry of these rocks suggests that they were formed most likely in an oceanic setting with clear plume-ridge interaction. These rocks can form from partial melting of a highly heterogeneous mantle source, which is extensively metasomatized with deep mantle OIB-type components. We suggest these rocks have been generated in an oceanic ridge with plume-ridge interaction, similar to the Iceland-Reykjanes Ridge, before being fragmented and accreted into the Makran accretionary complex.  相似文献   

Biostratigraphy and seismic data analysis to detect the sequence stratigraphic depositional environment of the Miocene succession: Gulf of Suez (Egypt)     

Ahmed Abd El Naby  Wafaa Abd-Elaziz  Mohamed Hamed Abdel Aal 《Swiss Journal of Geoscience》2017,110(3):777-791

This work comprises a study of the sequence stratigraphy, seismic-facies analysis, biostratigraphy and depositional environments of the northern part of the Gulf of Suez, Egypt, using a set of 24 3D seismic profiles, composite logs and sonic logs from ten wells. The syn-rift formations in the studied ten wells are described lithologically and interpreted based on investigating two seismic profiles. Biostratigraphically, the Miocene fossils are identified to correlate the five planktonic foraminiferal biozones in the examined boreholes (RB-A1, RB-B1, RB-B3, EE85-2 and RB-C1). The sequence stratigraphic analysis suggests that the Miocene succession can be subdivided into two major third order depositional sequences (S1 and S2) separated by the three major sequence boundaries (DSB1, DSB2 and DSB3).  相似文献   

Origin of dyke swarms in Wadi El Redi-Wadi Lahami area,southern Eastern Desert of Egypt     

Mohamed M. Hamdy  Mohamed A. Abd El-Wahed  Ismaeel A. Thabet 《Arabian Journal of Geosciences》2017,10(18):414

Dykes predominate within the Neoproterozoic rocks, especially granites, of Wadi El Redi-Wadi Lahami area in the southern Eastern Desert of Egypt. The dyke swarms form three major suites: from the oldest to the youngest, they are basaltic andesite—Suite 1 (E-W and ENE-WSW), rhyolite—Suite 2 (NE-SW), and andesite—Suite 3 (NNE-SSW, NNW-SSE, and NW-SE). Despite the wide ranges of the dyke compositions, the feldspar and amphibole are usually the essential forming minerals. The plagioclase arrays between Ab_0.9An_99.10 in the basaltic andesite and Ab_98.80An_0.70 in the rhyolite, while sanidine ranges from Or_44.60Ab_49.70 to Or_98.40Ab_1.60. Amphibole in Suite 1 and 3 (Al₂O₃, TiO₂, Na₂O, and K₂O are the lowest and those of SiO₂ and CaO are the highest) samples are usually magnesio-hornblende, whereas it is edenite and tschermakite in Suite 2 dykes. Despite all parent magmas have calc-alkaline affinity, some elements such as Ni show an erratic behavior against the progressing differentiation from one magma chamber and implying for an assimilation of the country rocks. The high contents of amphibole, the depletion in Ti, and the enrichment in large-ion lithophile elements (such as K, Rb, Ba, Sr, and Ba) compared to the primitive mantle composition are consistent with parent hydrous melts generated due to extension above the subduction zone. The estimated compositions of liquids in equilibrium with amphiboles and the pressures at which they crystallized (4.61–7.8 kbar for the Suite 2 and 1.5–2 kbar for the Suites 1 and 3) are greatly varied. These are indications for a difference in the source regions of the parent magmas of the studied dykes. It is supposed that the Suite 1 and 2 dykes are a conjugate set emplaced due to the NW-SE crustal extension in the Arabian-Nubian shield, whereas the Suite 3 dykes generated due to the rifting along the Red Sea.  相似文献   

Strain geometry,microstructure and metamorphism in the dextral transpressional Mubarak Shear Belt,Central Eastern Desert,Egypt     

M. A. Abd El-Wahed  I. A. Thabet 《Geotectonics》2017,51(4):438-462

Mubarak shear belt provides an opportunity to investigate quantitative finite strain (Rs), proportions of pure shear and simple shear components, sense of shear indicators, subhorizontal to steeply plunging mineral lineations, in a dextral transpressional zone. The structural style of the Mubarak shear belt is consistent with dextral transpression within the Central Eastern Desert where dextral and reverse shear have developed simultaneously with the regional foliation. The high strain zone of the Mubarak shear belt is characterized by steeply dipping foliation with sub-horizontal stretching lineation (simple shear) surrounded by thrust imbrications with slightly plunging stretching lineations. Strain estimates from the Mubarak shear belt are used to determine how pure and simple shear components of deformation are partitioned. The axial ratios in XZ sections range from 1.16 to 2.33 with the maximum stretch, S _X , ranges from 1.06 to 1.48. The minimum stretch, S _Z , ranges from 0.65 to 0.92 indicating a moderate variation in vertical shortening. Volcaniclastic metasediments and metagabbros were subjected to prograde low-grade regional metamorphism in the range of greenschist to lower amphibolite facies (450–650°C at 2–4 kbar). Medium pressure (6–8 kbar at 530°C) was estimated from the high strain zone within the dextral strike-slip shear zones. Retrograde metamorphism occurred at a temperature range of 250–280°C. There is a trend towards decreasing the ratio of 100Mg/(Mg + Fe_tot + Mn) away from the high strain zone of the Mubarak shear belt. Integrated strain and temperature estimates indicate that the simple shear (non-coaxial) components of deformation played a significant role in formation and exhumation of the Mubarak shear belt during the accumulation of finite strain and consequently during progressive transpression and thrusting.  相似文献   

Surfactants in the sea-surface microlayer and their contribution to atmospheric aerosols around coastal areas of the Malaysian peninsula     

Razarul Naim Roslan  Mohamed Rozali Othman  Xan Xue Yan  Che Abd Rahim Mohamed 《Marine pollution bulletin》2010,60(9):1584-5700

A study was done to determine the concentrations of surfactants on the sea-surface microlayer and in atmospheric aerosols in several coastal areas around the Malaysian peninsula. The concentrations of surfactants from the sea-surface microlayer (collected using rotation drum) and from aerosols (collected using HVS) were analyzed as methylene blue active substances and disulphine blue active substances through the colorimetric method using a UV-vis spectrophotometer. The results of this study showed that the average concentrations of surfactants in the sea-surface microlayer ranged between undetected and 0.36 ± 0.34 μmol L⁻¹ for MBAS and between 0.11 ± 0.02 and 0.21 ± 0.13 μmol L⁻¹ for DBAS. The contribution of surfactants from the sea-surface microlayer to the composition of surfactants in atmospheric aerosols appears to be very minimal and more dominant in fine mode aerosols.  相似文献   

Synoblique convergent and extensional deformation and metamorphism in the Neoproterozoic rocks along Wadi Fatira shear zone, Northern Eastern Desert, Egypt     

Mohamed Abd El-Wahed  Mohamed Abu Anbar 《Arabian Journal of Geosciences》2009,2(1):29-52

The Wadi Fatira area occurs at the southern margin of the Northern Eastern Desert (NED) of Egypt and is occupied by highly sheared metavolcanics tectonically alternated with banded iron formations and intruded by Barud tonalite–granodiorite, post-tectonic gabbroic and granitic intrusions. Detailed structural investigation showed that the schists and migmatitic amphibolites are formed by shearing in metavolcanics and syntectonic Barud tonalite–granodiorite due to movement along the Wadi Fatira shear zone (WFSZ). This shear zone starts as a NW–SE striking fault along Wadi Barud Al Azraq and the Eastern part of Wadi Fatira and turns to a E–W trending fault to the north of Wadi Fatira. Microstructural shear sense indicators such as asymmetric geometry of porphyroclasts such as σ-type and asymmetric folds deforming fine-grained bands which are frequently found around porphyroclasts indicate sinistral sense of shearing along the WFSZ. This shear zone is characterized by transitions from local convergence to local extension along their E–W and NW–SE trending parts, respectively. The NW–SE part of the WFSZ is of about 200 m in width and characterized by synmagmatic extensional features such as intrusion of synkinematic tonalite, creation of NE–SE trending normal faults, and formation of migmatitic amphibolites and schlieric tonalites. This part of the shear zone is metamorphosed under synthermal peak metamorphic conditions (725°C at 2–4 kbar). The E–W compressional part of the WFSZ is up to 3 km in width and composed of hornblende, chlorite, actinolite, and biotite schists together with sheared intermediate and acidic metatuffs. Contractional and transpressional structures in this part of the WFSZ include E–W trending major asymmetrical anticline and syncline, nearly vertical foliation and steeply pitching stretching lineations, NNE dipping minor thrusts, and minor intrafolial folds with their hinges parallel to the stretching lineation. P–T estimates using mineral analyses of plagioclase and hornblende from schists and foliated metavolcanics indicate prograde metamorphism under medium-grade amphibolite facies (500–600°C at 3–7 kbar) retrogressed to low-grade greenschist facies (227–317°C). The foliation in Barud tonalite–granodiorite close to the E–W part of the WFSZ runs parallel to the plane of shearing and the tonalite show numerous magmatic flow structures overprinted by folding and ductile shearing. The WFSZ is similar to structures resulted from combined simple shear and orthogonal shortening of oblique transpressive shear zones and their sense of movement is comparable with the characteristics of the Najd Fault System.  相似文献   

Testing a 1-D analytical salt intrusion model and its predictive equations in Malaysian estuaries     

J.I.A. Gisen  H.H.G. Savenije  R.C. Nijzink  A.K. Abd. Wahab 《水文科学杂志》2013,58(1):156-172

Abstract

Little is known about the salt intrusion behaviour in Malaysian estuaries. Study of salt intrusion generally requires large amounts of data, especially if 2-D or 3-D numerical models are used; thus, in data-poor environments, 1-D analytical models are more appropriate. A fully analytical 1-D salt intrusion model, which is simple to implement and requires minimal data, was tested in six previously unsurveyed Malaysian estuaries (Kurau, Perak, Bernam, Selangor, Muar and Endau). The required data can be collected during a single day of observations. Site measurements were conducted during the dry season (June–August 2012 and February–March 2013) near spring tide. Data on cross-sections (by echo-sounding), water levels (by pressure loggers) and salinity (by moving boat) were collected as model input. A good fit was demonstrated between the simulated and observed salinity distribution for all six estuaries. Additionally, the two calibration parameters (the Van der Burgh coefficient and the boundary condition for the dispersion) were compared with the existing predictive equations. Since gauging stations were only present in some nested catchments in the drainage basins, the river discharge had to be up-scaled to represent the total discharge contribution of the catchments. However, the correspondence between the calibration coefficients and the predictive equations was good, particularly in view of the uncertainty in the river discharge data used. This confirms that the predictive salt intrusion model is valid for the cases studied in Malaysia. The model provides a reliable, predictive tool, which the water authority of Malaysia can use for making decisions on water abstraction or dredging.