Ajji Z.,Syrian Atomic Energy Commission |
Ali A.M.,Tishreen University
Journal of Hazardous Materials | Year: 2010
Acrylic acid (AAc), N-vinyl imidazole (Azol) and their binary mixtures were graft copolymerized onto poly(vinyl alcohol) membranes using gamma irradiation. The ability of the grafted membranes to separate Cu ions from Fe ions was investigated with respect to the grafting yield and the pH of the feed solution. The data showed that the diffusion of copper ions from the feed compartment to the receiver compartment depends on the grafting yield of the membranes and the pH of the feed solution. To the contrary, iron ions did not diffuse through the membranes of all grafting yields. However, a limited amount of iron ions diffused in strong acidic medium. This study shows that the prepared membranes could be considered for the separation of copper ions from iron ions. The temperature of thermal decomposition of pure PVA-g-AAc/Azol membrane, PVA-g-AAc/Azol membrane containing copper ions, and PVA-g-AAc/Azol membrane containing iron ions were determined using TGA analyzer. It was shown that the presence of Cu and Fe ions increases the decomposition temperature, and the membranes bonded with iron ions are more stable than those containing copper ions. © 2009 Elsevier B.V. All rights reserved.
Dayoub N.,Newcastle University |
Dayoub N.,Tishreen University |
Edwards S.J.,Newcastle University |
Moore P.,Newcastle University
Journal of Geodesy | Year: 2012
In geopotential space, the fundamental geodetic parameter W 0 defines the Gauss-Listing geoid which can be used to best represent the Earth's mean sea level (MSL) and hence specifies a conventional zero height level to unify vertical datums employed by mapping agencies throughout the world. Further, W 0 cannot be considered invariant as the parameter varies temporally as a direct response to sea level change and mass redistributions. This study determines W 0 and its rate, dW 0/dt, by utilizing altimetric MSL models and an independent mean dynamic topography (MDT) model to define points on the geoid. W 0 and dW 0/dt are estimated by two approaches: (i) by means of a global gravity field model (GGM) and (ii) within normal gravity field space as the geopotential value of the best fitting reference ellipsoid. The study shows that uncertainty in W 0 is mainly influenced by MDT while the choice of methodology, GGM and MSL data coverage are not significant within reason. Our estimate W 0 = 62636854. 2 ± 0. 2 m 2 s -2 at epoch 2005. 0 differs by 1. 8 m 2s -2 from the International Astronomical Union reference value. This study shows that, at a sub-decadal time scale, the time variation dW 0/dt stems mainly from sea level change with negligible effect from gravity field variations. dW 0/dt = (-2. 70 ± 0. 03) × 10 -2 m 2 s -2 year -1, corresponding to a MSL rise of 2. 9 mm year -1, is evaluated from sea level change based on 16 years of TOPEX and Jason-1 data. © 2012 Springer-Verlag.
Ghadeer S.G.,University of Manchester |
Ghadeer S.G.,Tishreen University |
Macquaker J.H.S.,Memorial University of Newfoundland
Marine and Petroleum Geology | Year: 2012
Geologists have recently observed that source rocks commonly contain a wide variety of microfabrics, including diminutive ripples and burrows. The existence of these fabrics challenges the assumption that persistent bottom-water anoxia and low-energy conditions are necessary prerequisites for enhanced organic carbon preservation in these units. In order to enhance our understanding of the depositional and diagenetic processes responsible for organic carbon preservation in these strata, the lower Jurassic Whitby Mudstone Formation, which contains mudstones with up to 14.2% total organic carbon, has been investigated using optical, electron optical and geochemical methods. Four thinly-bedded mudstone lithofacies were identified: (a) silt-bearing, clay-rich mudstones; (b) clay-rich mudstones; (c) clay-, calcareous nannoplankton-, and organic carbon-bearing mudstones; and (d) cement-rich mudstones. Internally individual beds are typically sharp-based and, normally-graded. They are either laminated, partially bioturbated or homogenized. Where depositional fabrics are preserved, pellets, silt lags, ripple lamination, shell pavements, wave enhanced sediment gravity flows of fluid mud, and organo-minerallic aggregates have been observed. The presence of up to 14.2% TOC in units that are sharp based and normally-graded suggests that mass flows, possibly generated by storms likely influenced sedimentation during deposition of these mudstones. The abundant organo-minerallic fabrics in these units indicates that at least some of the organic carbon was delivered to the seafloor as marine snow aggregates, that likely formed in the water column following phytoplankton blooms. Homogenization of bed tops indicates that between sediment delivery episodes, an infauna was able to colonize the seafloor, implying that the bottom waters were at least partly oxygenated during these intervals. These fabrics suggest that during deposition of the Whitby Mudstone Formation, organic carbon was being preferentially preserved below regions of high primary organic production. The close association between sharp-based, graded beds and organo-minerallic aggregates indicates that large volumes of organic carbon were delivered episodically to the seafloor, and that conditions at the sediment-water interface were episodically dynamic. Here organic carbon is likely to have been preferentially preserved because the frequency of depositional events was sufficiently high to minimize both oxidant diffusion into the sediment and organic carbon mineralization. While bottom water anoxia may have developed during the phytoplankton blooms, it was unlikely to have been persistent, because the microfabrics present indicate that there was sufficient time and oxygen available for an infauna to disrupt the sediment between deposition events. © 2012 Elsevier Ltd.
Shaheen H.I.,Tishreen University |
Rashed G.I.,Huazhong University of Science and Technology |
Cheng S.J.,Huazhong University of Science and Technology
Engineering Applications of Artificial Intelligence | Year: 2010
Unified power flow controller (UPFC) is one of the most effective flexible AC transmission systems (FACTS) devices for enhancing power system security. However, to what extent the performance of UPFC can be brought out, it highly depends upon the location and parameter setting of this device in the system. This paper presents a new approach based on computational intelligence (CI) techniques to find out the optimal placement and parameter setting of UPFC for enhancing power system security under single line contingencies (N-1 contingency). Firstly, a contingency analysis and ranking process to determine the most severe line outage contingencies, considering lines overload and bus voltage limit violations as a performance index, is performed. Secondly, a relatively new evolutionary optimization technique, namely: differential evolution (DE) technique is applied to find out the optimal location and parameter setting of UPFC under the determined contingency scenarios. To verify our proposed approach and for comparison purposes, simulations are performed on an IEEE 14-bus and an IEEE 30-bus power systems. The results, we have obtained, indicate that DE is an easy to use, fast, robust and powerful optimization technique compared with genetic algorithm (GA) and particle swarm optimization (PSO). Installing UPFC in the optimal location determined by DE can significantly enhance the security of power system by eliminating or minimizing the number of overloaded lines and the bus voltage limit violations. © 2009 Elsevier Ltd. All rights reserved.
Bontemps A.,Joseph Fourier University |
Ahmad M.,Tishreen University |
Johanns K.,French Scientific and Technical Center for Building |
Sallee H.,French Scientific and Technical Center for Building
Energy and Buildings | Year: 2011
An experimental and numerical simulation study of the application of phase change materials (PCMs) in building components is presented for thermal management of a passive solar test-room. The experimental study was conducted in an outdoor test cell constituted of two small rooms separated with a wall containing PCM. A specific wall made of hollow glass bricks filled with PCM was studied. Three PCMs were tested: fatty acid, paraffin, and salt hydrate whose melting temperatures are 21 °C, 25 °C and 27.5 °C respectively. Indoor and outdoor temperatures were measured with thermocouples. Ten fluxmeters located at the centre of each wall allowed us to measure the heat fluxes across the walls. Tests were carried out in real climatic conditions. A one-dimensional numerical model has been developed to simulate the transient heat transfer process in the walls. Reasonable agreement between the simulation and the experimental results was observed. © 2011 Elsevier B.V. All rights reserved.
Al-Moustafa T.,University of Salford |
Al-Moustafa T.,Tishreen University |
Armitage R.P.,University of Salford |
Danson F.M.,University of Salford
Remote Sensing of Environment | Year: 2012
This paper tests the application of airborne hyperspectral image data for estimating live vegetation fuel moisture content (FMC) in a Calluna vulgaris-dominated semi-natural upland area in the United Kingdom. Airborne hyperspectral imagery was collected over a north/south flight line covering the study site in May and July 2008. Ground data on live FMC were collected concurrently with the flights for ten study plots. Radiance values for the study plots were extracted from the airborne imagery and calibrated to reflectance using spectral measurements from reference targets measured on the ground at the time of the overflights. First derivatives, and a number of vegetation indices (VI), were calculated and correlated with field measured live FMC collected at the study plots. Vegetation FMC maps were produced for the study site for both dates. The results showed that live FMC exhibited spatial and temporal variations that affect the spectral reflectance measured by the airborne hyperspectral instrument, particularly in the near infrared and shortwave infrared regions. Using the first derivative and specific VI improved the correlation between the hyperspectral data and live FMC, but the simple two-wavelength Moisture Stress Index, based on measurements in the near infrared and shortwave infrared, was shown to be effective for FMC estimation. Live FMC was estimated with a root mean square error of 16.8% for all vegetation plots and 10.0% when considering plots composed only of C. vulgaris. The results point to the prospect of FMC mapping for improved modelling of fire risk in UK uplands using remotely sensed data. © 2012 Elsevier Inc.
Durgham H.,Tishreen University
International Journal of Oceans and Oceanography | Year: 2011
The gelatinous Phyllorhiza punctata von Lendenfeld, 1884 (Cnidaria: Scyphozoa: Rhizostomeae) is recorded for the first time from the Syrian coasts of the Eastern Mediterranean (Levantine basin). This species is a tropical jellyfish with a distribution range from Australia to Japan. Invasive migrations to several other tropical seas outside its main habitat are recorded. In the Mediterranean Sea, P. punctata have been recorded from many region of the western and eastern Mediterranean. © Research India Publications.
Hassan M.,Tishreen University
Marine Biodiversity Records | Year: 2013
A large specimen of a female large-eyed rabbitfish, Hydrolagus mirabilis, known previously only from the eastern and western Atlantic, was recorded for the first time in the eastern Mediterranean. Its morphometric and meristic characteristics are reported. © Marine Biological Association of the United Kingdom 2013.
Achtar S.,Tishreen University
Genetika | Year: 2010
Genetic diversity among 49 wheat varieties (37 durum and 12 bread wheat) was assayed using 32 microsatellites representing 34 loci covering almost the whole wheat genome. The polymorphic information content (PIC) across the tested loci ranged from 0 to 0.88 with average values of 0.57 and 0.65 for durum and bread wheat respectively. B genome had the highest mean number of alleles (10.91) followed by A genome (8.3) whereas D genome had the lowest number (4.73). The correlation between PIC and allele number was significant in all genome groups accounting for 0.87, 074 and 0.84 for A, B and D genomes respectively, and over all genomes, the correlation was higher in tetraploid (0.8) than in hexaploid wheat varieties (0.5). The cluster analysis discriminated all varieties and clearly divided the two ploidy levels into two separate clusters that reflect the differences in genetic diversity within each cluster. This study demonstrates that microsatellites markers have unique advantages compared to other molecular and biochemical fingerprinting techniques in revealing the genetic diversity in Syrian wheat varieties that is crucial for wheat improvement.
Hajjar A.A.,Tishreen University
Electric Power Systems Research | Year: 2013
This paper presents a high-speed protection scheme for power transmission lines based on wavelet transform (WT). It is a noncommunication protection scheme as it depends completely on locally measured currents. It utilizes WT, which acts as a multi-level bandpass filter, to extract two distinct bands of frequency from the fault induced high frequency (HF) transient currents; the first band is high while the second band is relatively lower. The spectral energies of the extracted signals are then calculated to form two discriminating signals of the relay (operative and restraint). Based on the ratio between these discriminating signals the relay can distinguish whether a fault is internal or external to the protected line. The performance of the introduced protection scheme was evaluated by simulating several faults on 400 kV-50 Hz transmission system using an electro magnetic transient program (EMTDC). The simulation results showed distinct performance of the scheme irrespective of the fault type, fault inception angle, fault position and fault resistance. Moreover, it is not affected by a system configuration and system source parameters. © 2012 Elsevier B.V.