Temporal and spatial distribution of dissolved Cu, Ni and Zn in the coastal waters of Jeddah, eastern Red Sea     

Radwan K. Al-Farawati  Mohammad O. Gazzaz  Mohammad A. El Sayed  Amr El-Maradny 《Arabian Journal of Geosciences》2011,4(7-8):1229-1238

Dissolved Cu, Ni, and Zn were measured in the surface coastal waters of Jeddah, eastern Red Sea during October 2004 and April 2005. High values of trace metals, particularly Zn, were recorded in the Southern Corniche area close to a sewage effluent indicating a significant contribution from the wastewater. Concentrations of trace metals decreased northward and southward under the effect of dilution. Another hot spot was also observed in the vicinity of Jeddah Desalination Plant (JDP) during April 2005 indicating a possible contribution from the JDP to trace metal contents in the study area. Trace metals were correlated to salinity, nutrients and particulate organic carbon (POC). The good association between Zn and reactive silicate and Ni and ammonium is attributed to simultaneous biological utilization and regeneration. The behavior of copper suggested adsorption of Cu onto the POC during October 2004 whereas in April 2005 the most important process seems to be desorption of Cu from the particulate materials.  相似文献   

Experimental investigation of water slamming loads on panels     

F.J. Huera-Huarte  D. Jeon  M. Gharib 《Ocean Engineering》2011,38(11-12):1347-1355

Rigid-body slamming has become increasingly important as ships travel at higher speeds experiencing larger loads during hull impacts against surface water which can result in structural damage and crew injury. It is necessary to characterise the hydrodynamic loading during water impacts.We present a series of experiments conducted in order to study slamming force events seen by flat plates during free surface impacts. The experiments focus on the characterisation of the loads experienced by flat plates during the first phase of the slamming event, the water entry. They have been conducted in an especially designed test apparatus, the Slingshot Impact Testing System (SITS), which allows us launching objects against the free surface of an open channel, with the possibility of setting up different speeds and deadrise angles. We can study slamming with trapped air between the plate and the water free surface, at high impact speeds and small deadrise angles, allowing us to quantify the resulting cushioning effect. High velocity impacts up to 5 m/s were conducted at angles between 0.3° and 25°. It was found that the trapped air phenomenon significantly cushions flat plate impacts with angles less than 5° and impacts with larger angles adhere to Von Kármán's equations.  相似文献   

The seabed characteristics of the bottom floor of Damietta Branch,Egypt, using acoustic signals     

Amr Z. Hamouda 《Environmental Earth Sciences》2014,71(12):5045-5058

The study area lies between 31.32°N, 31.70°E and 31.41°N, 31.78°E along Damietta branch, Nile River. It is about 24-km long. Acoustic classification (Quester Tangent Corporation—QTC) is used as a powerful tool to study seabed characteristics which is confirmed by the sediment analyses. Sediment characteristics of the study are presented by three acoustic classes: sand, mud and organic matter intercalated by clay. The depth varies from about ?12 m at Faraskour Bridge (southern part of the study area) to about ?2.5 m at Faraskour Dam (northern part of the study area). The average current velocity is detected as 4 cm/s and it has a very low effect on the transport of both sediment and waste debris. The sediment in the northern part characterized by organic matter reaches about 70 cm thickness under and around fish cages. This huge amount of organic matter deposit leads to the reduction of the dissolved oxygen and increase pH values. This study shows that the water quality in the northern part of the study area is at risk (drinking water for Damietta city) due to the presence of the huge amount of waste debris intercalated by organic matter. The rises of temperature in summer enhance oxygen consumption and the decomposition of the organic matter. This is rapidly increasing the growth of bacteria and phytoplankton, causing turbidity and algal blooms. Those affect the water quality and raise the water toxicity (drinking water).  相似文献   

Closest Approach in Universal Variables     

M. A. Sharaf  Amr A. Sharaf 《Celestial Mechanics and Dynamical Astronomy》1997,69(4):331-346

In this paper, universal formulations of the closest approach problem are established and solved by two methods. The first method uses the technique of one-dimensional unconstraint minimization and needs the solution of the universal Kepler's equation twice, while for the second method, a constraint minimization technique is developed and needs the solution of two nonlinear simultaneous equations. Flexible iterative schemes of quadratic up to any positive integer order are developed for the solution of the universal Kepler's equation. The two methods of the minimization process are applied for the closest approach of Hyakutake and Hale–Bopp comets, while the first method is applied to obtain the minimum angular separation of ADS 9159, ADS 2959 and ADS 11632 visual binaries as typical examples of elliptic, parabolic and hyperbolic orbits. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Simulation of temporal variation for reference evapotranspiration under arid climate     

Mossad  Amr  Alazba  A. A. 《Arabian Journal of Geosciences》2016,9(5):1-16

Interpretation of 2500 km of newly processed 2D seismic and regional potential field data has led to the identification of two new Miocene–Oligocene sedimentary basins in the northern part of offshore Egypt. The western part of the basin is deeper and has thick sedimentary cover. The upper part of the Miocene section is tested in its southern part through two wells, where the eastern subbasin is still virgin and is located at the intersection between Temsah basins and southeastern end of the Levantine basin. The main sedimentary unit of the basin is the Miocene–Oligocene sedimentary section, which was proven by the exploration and production activities in Nile Delta to be one of the hydrocarbon-generating facies. This fact is supported by 1D basin analysis using the average parameter values, which shows a hydrocarbon window, extending from lower Miocene to upper Miocene. The basin dimensions are more than 2000 km² area and more than 4000 m of thickness, with variable petroleum system parameters’ potentialities, starting from Tortonian–Serravallian to lower Oligocene section.

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Unified Symbolic Algorithm of Gauss Method for Near-Parabolic Orbits     

M. A. Sharaf  Abdel-Naby S. Saad  Amr A. Sharaf 《Celestial Mechanics and Dynamical Astronomy》1998,70(3):201-214

In this paper, a unified algorithm of Gauss method for near‐parabolic orbits that is valid for both elliptic and hyperbolic cases is established symbolically and numerically. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Determination and prediction of standardized precipitation index (SPI) using TRMM data in arid ecosystems     

Amr Mossad  A. A. Alazba 《Arabian Journal of Geosciences》2018,11(6):132

Drought over a period threatens the water resources, agriculture, and socioeconomic activities. Therefore, it is crucial for decision makers to have a realistic anticipation of drought events to mitigate its impacts. Hence, this research aims at using the standardized precipitation index (SPI) to predict drought through time series analysis techniques. These adopted techniques are autoregressive integrating moving average (ARIMA) and feed-forward backpropagation neural network (FBNN) with different activation functions (sigmoid, bipolar sigmoid, and hyperbolic tangent). After that, the adequacy of these two techniques in predicting the drought conditions has been examined under arid ecosystems. The monthly precipitation data used in calculating the SPI time series (SPI 3, 6, 12, and 24 timescales) have been obtained from the tropical rainfall measuring mission (TRMM). The prediction of SPI was carried out and compared over six lead times from 1 to 6 using the model performance statistics (coefficient of correlation (R), mean absolute error (MAE), and root mean square error (RMSE)). The overall results prove an excellent performance of both predicting models for anticipating the drought conditions concerning model accuracy measures. Despite this, the FBNN models remain somewhat better than ARIMA models with R?≥?0.7865, MAE?≤?1.0637, and RMSE?≤?1.2466. Additionally, the FBNN based on hyperbolic tangent activation function demonstrated the best similarity between actual and predicted for SPI 24 by 98.44%. Eventually, all the activation function of FBNN models has good results respecting the SPI prediction with a small degree of variation among timescales. Therefore, any of these activation functions can be used equally even if the sigmoid and bipolar sigmoid functions are manifesting less adjusted R² and higher errors (MAE and RMSE). In conclusion, the FBNN can be considered a promising technique for predicting the SPI as a drought monitoring index under arid ecosystems.  相似文献   

Glutamic Acid Modified Fenton System for Degradation of BTEX Contamination     

Fatma Z. Yehia  Nadia G. Kandile  Abdelfatah M. Badawi  Amr H. Mady 《洁净——土壤、空气、水》2012,40(7):692-697

The present study employed a modified Fenton system that aims to extend the optimum pH range towards neutral conditions for studying the oxidation of benzene, toluene, ethyl benzene, xylenes (BTEX) using glutamic acid (Glu) as an iron chelator. Addition of 20 mM Glu greatly enhanced the oxidation rate of BTEX in modified Fenton system at pH 5–7. A rapid mass destruction (>97% after 1 h) of BTEX as a water contaminant carried out in the presence of 500 mM H₂O₂, 10 mM Fe²⁺, and 20 mM Glu at pH 5 could be shown. The efficiency of this modified Fenton's system for mass destruction of BTEX in contaminated water was measured to estimate the impact of the major process variables that include initial concentrations of soluble Fe, H₂O₂, Glu (as metal chelating agent), and reaction time.  相似文献   

A reanalysis of the AD 365 tsunami impact along the Egyptian Mediterranean coast     

Amr Z. Hamouda 《Acta Geophysica》2010,58(4):687-704

The historical tsunamigenic event of 21 July AD 365 destroyed several coastal locations in the Eastern Mediterranean region. The foremost destructive impacts were recorded in Crete and Egypt. The present study re-examines the effect of location, direction, height and time of travel of the tsunami towards the Egyptian coast. Evidently, this tsunamigenic event is related to an earthquake which is identified with a Hellenic Arc subduction-zone event of great magnitude, M > 8, as manifested by up to 9 m uplift in western Crete. The maximum run-up height distribution in the front of the Nile Delta was about 9.5 m in Alexandria, while those of the neighboring cities were 7.1 m, 4.9 m, and 1.9 m at Rashid, Damietta and El-Arish, respectively. Data obtained from this study is essential to evaluate the tsunami hazards along the Egyptian coast.  相似文献   

Spectral characteristics of natural and artificial seismic events in the Lop Nor test site, China     

Ibrahim M. Korrat  Ali A. Gharib  Kamal A. Abou Elenean  Hesham M. Hussein  Mohamed N. El Gabry 《Acta Geophysica》2008,56(2):344-356

Seismic discriminants based on the spectral seismogram and spectral magnitude techniques have been tested to discriminate between three events; a nuclear explosion which took place in Lop Nor, China with m _b 6.1 and two earthquakes from the closest area with m _b 5.5 and 5.3, respectively. The spectral seismogram of the three events shows that the frequency content of the nuclear explosion differs from that of the earthquakes where the P wave is richier in high frequency content in the nuclear explosion than the corresponding earthquakes. It is also observed that the energy decays more rapidly for the nuclear explosion than for the earthquakes. Furthermore, the spectral magnitudes reveal significant differences in the spectra between the nuclear explosion and the two earthquakes. The observed differences appear to be quite enough to provide a reliable discriminant. The estimated stress drop from the magnitude spectra indicates a higher stress drop of the nuclear explosion relative to the earthquakes of the same tectonic region.  相似文献