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1.
This study aims at evaluating the global geoid model for a regional shoreline fitting using advanced soft computing techniques and global navigation satellite system/leveling measurements. Artificial neural networks, fuzzy logic, and least square support vector machine models are developed and used to fit the global geoid model for the north coastal Egyptian line. In addition, a novel estimation geoid model is designed and evaluated based on the latest global geoid models. The results of the three estimation models show that they can be used to correct the shoreline geoid model, in terms of root mean square error that ranges from 1.7 to 8.5?cm. Moreover, it is found that the least square vector machine model is a competitive approach with certain advantage in solving complex problems represented by missing data.  相似文献   
2.
The Hassi R’Mel field, which is the largest gas field in Algeria, produces principally gas condensate. The produced gas and oil comes from four reservoirs of Triassic age (reservoir A, reservoir B, reservoir C, and the Lower Series). All the previous studies in this field focused only on the upper reservoirs (A, B, and C), which have shown an excellent petrophysical properties. However, due to the presence of shale facies as well as volcanic intrusions, the Lower Series reservoir has been less explored. Thus, our study is mainly focused on this Lower Series in order to find the best sandy levels. The aim of this paper was to determine the facies types in the area, their distribution in the southern area of the Hassi R’Mel gas field, and their depositional environment. The Triassic rocks in this field are divided into four formations. From the youngest to oldest, these are S4, Lower Shale, Horizon A, and the Lower Series. The Lower Series formation can be further divided into three members (shaly sandstone, andesite, and lower shale). The shaly sandstone member within the Lower Series is composed of four units that are present all over the study area with an important pinch-out toward the northern part. The depositional environment within the defined units is a braided fluvial system in the southern part that evolves into a meandering fluvial system toward the north. Thus, the study area is considered to be a transitional zone between two depositional systems.  相似文献   
3.
Earthquake response characteristic and sensitivity of 1-Hz Global Navigation Satellite System - precise point positioning (GNSS-PPP) for a seismic response in time and frequency domains are the main objectives of this study. The Delta and Cairo areas, Egypt, experiencing the shock of the Greece earthquake occurring on April 16, 2015 (18:50 hours), is presented in this study. The results of this study reveal that the seismic wave effect is very small and can be neglected inside the Delta region and the strong motion occurred in an upward direction for the whole monitoring area. Furthermore, the time-frequency analysis illustrates the ability of the time and frequency domains to use and analyze the surface motion based on a 1-Hz sampling frequency and to detect the small- and high-strength motions of seismic waves.  相似文献   
4.
Ocean Science Journal - Recently, there have been recorded findings of the pleustonic siphonophore Physalia physalis Linnæus, 1758, in different regions of Algeria. Several colonies washed...  相似文献   
5.
International Journal of Earth Sciences - Hydrothermal ore deposits at Aïn El Araâr-Oued Belif location are classified as epithermal deposits type. The ore bodies are hosted by upper...  相似文献   
6.
The differential code bias (DCB) is the differential hardware (e.g., the satellite or receiver) delay that occurs between two different observations obtained at the same or two different frequencies. There are two approaches used to estimate DCBs for receivers and satellites: the relative and absolute methods. The relative method utilizes a GPS network, while the absolute method determines DCBs from a single station (zero difference). Three receiver types based on the pseudo-range observables were used here to collect the GPS data: Codeless Tracking, Cross Correlation, and Non-Cross Correlation styles. According to its types, GPS receivers have responded to restrictions on the GPS signal structure in different ways. The main goal of the current research is providing a method to determine the DCBs of GPS satellites and dual frequency receivers. The developed mathematical model was based on spherical harmonic function and geometry-free combination of pseudo-range observables (C/A or/and P-code) according to receiver type. A new elevation-dependent weighting function with respect to GPS satellites in our algorithm was applied. The applied weighting function was used to consider the quality variation of satellite DCBs, which is caused by pseudo-range measurement errors. The code of the proposed mathematical model was written using MATLAB and is called “zero difference differential code bias estimation (ZDDCBE)”. This code was tested and evaluated using data from IGS GNSS stations and different types of GPS stations out of IGS network installed in Egypt and Saudi Arabia. The estimated values from the ZDDCBE code show a good agreement with the IGS analysis centers with a mean error of estimation for the receiver DCB equal 5.94%. Therefore, the ZDDCBE code can be used to estimate the DCB for any type of receiver regardless if the receiver is from IGS network or not.  相似文献   
7.
Building frequencies (fundamental and higher modes) are a critical parameter especially in the field of structural health monitoring mainly based on the stability of the structural dynamic parameters of individual building (frequencies, damping and modes shape). One of the most used methods to find out these parameters is based on the use on ambient vibration analysis. In this work, we study the fluctuations over a month period of the fundamental frequencies (transverse and longitudinal) of a 3.5-story RC-building made of 2 identical units connected by a structural joint. Time independent building frequencies is a strong assumption; as illustrated by our experiment showing that over an observation period of a month, building frequencies fluctuate of about 3.5 %. A clear correlation is found between the building frequency fluctuations and temperature variations, with a phase-shift interpreted as the characteristic time of heat diffusion within the walls. This allows: (1) determining the thermal diffusivity of the structure, (2) inferring its relative stiffness variations, and (3) showing that its Young modulus varies linearly with temperature.  相似文献   
8.
Results from geophysical investigations (electrical resistivity, electromagnetic mapping and seismic refraction) on an excavated cell of the Ouled Fayet (Algiers, Algeria) pilot landfill indicated the presence of an underground runoff and permeable soil underneath the cell. These results contradict those obtained by a feasibility study, based, however, only on the analysis of seventy-six 10-m drilling cores. The 1D boreholes information has been proven to be insufficient and to give biased results. The presence of water at depth is evidenced by lower resistivity, high conductivity anomalies and increase of P-wave velocity. Thus, to the contrary of what is claimed in the feasibility study, a threat of leachate pollution is real. This study shows that landfill construction studies cannot give trustful results without geophysical investigations. More specifically, in Algeria, it is imperative to elaborate a landfill construction code, which should include mandatory geophysical prospecting and deeper drilling cores.  相似文献   
9.
The original version of this paper was published with incomplete affiliation. Given in this article are the complete affiliations.  相似文献   
10.
Petrographic and geochemical analysis of the Hamra Quartzite reservoir in the southern periphery of the Hassi Messaoud field has been undertaken. The aim is to identify the quality of these sandstones as well as their tectonic setting and possible provenance. Petrographic analysis reveals that the studied reservoir is constituted of fine- to coarse-grained sandstones in which quartz forms the principal framework mineral. The main cement phases identified in this reservoir are quartz, illite, and carbonate, precipitated in that order. The principal diagenetic factors controlling the reservoir quality are quartz overgrowths, formation of authigenic clays, and the precipitation of carbonate cement. The Hamra Quartzite reservoir is considered mature from a compositional point of view as it consists predominantly of quartz arenites. Geochemically, these sandstones have a high SiO2 content (93.28–98.79 wt%). The Hamra Quartzite deposits appear to be derived from deeply weathered (under warm–humid climate conditions) granitic–gneissic terrains or recycled sedimentary source areas. A passive margin origin is the most likely tectonic setting for the depositional environment of these arenites. The reservoir quality is strongly influenced by the relationship between the clay content and mineralogy. The combined effect of quartz overgrowth and the plugging of pores by illite have reduced both porosity and permeability. As a result, economically viable oil production in this area will depend most strongly on the combination of matrix and fracture porosity.  相似文献   
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