Algerian Journal of Engineering and Technology (AJET)
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Electrodeposition of CaCO3 on stainless steel 316 L substrate: influence of thermalhydraulics and electrochemical parameters
No full textIn this paper we study the effect of the hardness, the rotation speed, the temperature and the cathodic polarization on calcium carbonate scale deposit on rotating stainless steel electrode using electrochemical techniques. The scale deposit was investigated by X-Ray diffraction, scanning electron microscope, Infra-red spectroscopy and electrochemical impedance spectroscopy (EIS). The electrochemical results show that the Oxygen Reduction Reaction (ORR), which is responsible of CaCO3 electrodeposition, takes place with 4 electrons at low rotation speed and 2 electrons at high rotation speed. The morphology of the CaCO3 deposit shows that the crystals formed in the center of the electrode have small sizes compared to those of the periphery. Whatever the hydrodynamic or thermodynamic conditions, the Calcite form remains predominant. Other forms appear in particular conditions: at high temperature the aragonite form and at high cathodic polarization the vaterite form.
 
DFT and molecular dynamic simulation study on the corrosion inhibition of Aluminum by some flavonoids of Guiera Senegalensis leaves
No full textQuantum chemical calculations and molecular dynamics simulations were performed to investigate the effect of four flavonoids compounds (Kaempferol, Quercetin, Myricetin and Rhamnetin) from Guiera Senegalensis leaves on corrosion inhibition of aluminium metal in vapour phase. Quantum chemical parameters including EHOMO, ELUMO, energy gap (ΔE), electronegativity (χ), global hardness (η), global softness (σ) and fraction of electrons transferred (ΔN) from the flavonoid molecule to the aluminium surface were calculated and the results indicate that the larger the molecular size the better the inhibition efficiency. Local reactive sites through Fukui indices were also calculated to explain the effect of electronic and structural features of the flavonoid compounds present in the leaves extract of Guiera senegalensis (GS). The results showed that the point of interaction of inhibitor molecule with the Al(1 1 0) surface were through hydroxyl and carbonyl functional groups of the studied compounds. Molecular dynamic simulations revealed that the adsorption behaviour of each flavonoid molecule on Al(1 1 0) surface through quench dynamics were found to obey the mechanism of physical adsorption and the more negative is the adsorption energy between the inhibitor-metal surface the better inhibition performance of the molecule on Al(1 1 0) surface.
 
Assessing the farmers’ awareness and practices of irrigation water conservation techniques in Kano – Nigeria
Get PDFIrrigation water conservation methods are strategies for reducing water demand and increasing its availability. This research assessed the level of farmers’ awareness and practices of irrigation water conservation methods in Kano State, Nigeria. A survey was conducted in twenty (20) irrigation projects located at various local government area within the state. Structured questionnaire was used in collecting information from the farmers using Kobo collect application and descriptive statistic was used to analyses the data obtained. Based on the result obtained from the survey 85.68% of the respondent’s uses dams as their source of irrigation water while 10.59% and 3.73% uses tube well and river as their sources of water, respectively. The survey revealed that 74.12% of the farmers do not experience decline in water supply while 25.88% of farmers encounter shortage of water supply, and this may result from seepage loses, present of weed or siltation of the conveyance canals at the upstream of the schemes. However, about 62.94% of the responded were unaware and do not practice any water conservation techniques while 27.84% and 9.22% were applying manure and rice straw, respectively to conserve moisture as a means of water conservation. It was concluded that the irrigation water conservation is poorly practiced by the farmers in Kano State and it is based on this note that government, water users’ associations and other stakeholders should provide a policy that encourage farmers to adopt some water conservation techniques and concepts for optimum utilization of water resource.
 
Application of HEC-RAS model for adaptive water allocation in a Large-Scale Rice Irrigation Scheme
No full textWater allocation is a key component of good water management in an irrigation system. Water imbalance between upstream and downstream has been a major issue at Tanjung-Karang Rice Irrigation Scheme Malaysia. This study applied the HEC-RAS model to estimate water for supply and analysed its allocation to the demand in the scheme. Water demand was computed based on water requirement, effective rainfall and seepage/percolation. Results of R2, NSE, PBIAS and RSR during the model calibration and validation were 0.66, 0.64, 0.94 and 0.60; and 0.65, 0.59, 1.77 and 0.64, respectively. The irrigation scheme was under-supplied from January-March and over-supplied from April-June during the off-season. While in the main-season was under-supplied from July-September and over-supplied from October-December. Similarly, the excess water during the off and main seasons for the period was 40.10 and 52.40 Mm3 respectively. Whiles the deficit water during the same seasons was 52.46 and 53.14 Mm3, respectively. This suggests providing an adequate storage facility, which could store excess water during low water demand and use it in the period of water shortage. The developed model could therefore assist in estimating the over/under-supply with respect to the demand thereby storing the excess for use during the period of high demand.
 
Gamma spectrometry for natural radioactive nuclides in Spa waters in some areas in north Algeria
No full textThe work aims to determine the radioactivity levels of Algeria thermal waters which have been used permanently in spas for therapeutic intentions. Eight Spas waters in north Algeria analysis was performed to determine their radioactivity concentration for 226Ra, 232Th, 235U and 40K, using a high-resolution HPGe γ-spectrometry system. Water is imbedded in a Marinelli beakers tightly sealed for 28 days to achieve secular equilibrium between 226Ra and its short-lived daughter products before analyzing by gamma ray spectrometry. The average activity concentrations for spa waters from study areas were 0.045 to 2.077 Bql-1 for 226Ra; 0.17to 3.416 Bql-1 for 232Th; 0.085to 7,235 Bql-1 for 235U and 1.402 to 15.156 Bql-1 for 40K. This study would be useful for used and official authorities for the assessment of radiation exposure risk due to usage of the considered spa waters.
 
Impact of climate change on the spatiotemporal variability of a coastal ecosystem in the Tunisian Sahel
No full textWetlands are some of the most important ecosystems on Earth. Despite their importance for water and carbon cycle regulation, wildlife survival and economic value. Furthermore, wetlands are experiencing rapid degradation due to severe transformations. They have been polluted and declined dramatically as land cover has changed in many regions. Whereas, human activities along with severe climate changes have led to critical loss and degradation of these ecosystems. This study evaluates changes of Halq El Mingel wetland, Tunisia, between 2006 and 2017. Spatial and temporal dynamics of wetland changes were quantified using Landsat and Google Earth images and three radiometric indexes have been calculated; Normalized Difference Vegetation Index, Normalized Difference Water Index and Salinity Index. Results revealed that important spatial and temporal variations are detected for each index.Also, the area of wetland in Hergla city decreased significantly over the last 10 years from 1146.7 ha to 806.6 ha respectively. A notable change is the shrinkage of the wetland area during 2006-2017 period which is linked to the decline of rainfall over the years. This study proposes a methodology to monitor changes in wetland using geospatial technology and thus to support decision-making for sustainable management.
 
Synthesis, characterization and antimicrobial studies on Mn(II), Fe(II), Co(II) complexes of schiff base derived from 3-Formylchromone and Benzohydrazide
No full textSchiff base formed by condensation of 3-formylchromone and benzohyrazide and its metal(II) complexes of Mn(II), Fe(II), and Co(II), have been prepared and characterized by conductivity measurement, magnetic susceptibility, IR Spectra, atomic absorption spectroscopy, elemental analysis, as well as melting point/decomposition temperature and solubility test. The melting point of the Schiff base (165 0C) and decomposition temperatures of the complexes (185-198)0C indicating their thermal stability. The molar conductivity measurement determined are in the range (10.54-23.10) Ω-1cm2mol-1 revealing that all the complexes are non-electrolytic in nature. IR spectra of the Schiff base showed a band at 1633cm-1 which assigned to ʋ(-C=N-) stretching vibration. This band was observed downfield in the range (1603 -1655) cm-1 in the spectra of the metal(II) complexes revealing that the Schiff base formed metal complexes with the metal ions. The gram magnetic susceptibility measurements of the complexes showed that all the complexes except that of Zinc are paramagnetic and have tetrahedral geometry. The elemental analysis suggested a metal to ligand ratio of 1:1. The Schiff base and its metal complexes have been screened for their antimicrobial activity against four pathogens. Some compounds were active, while others are not active against the isolates.
 
Color Component Based Lossless Compression Method for Satellite Images (CCBLC)
No full textIn recent years, the development and demand of remote sensing images are increased rapidly, however the huge volume of satellite images are contributing to inadequate bandwidth of network and storage of memory device. Therefore, the hunt of data compression methods becomes more and more significant to reduce the data redundancy to save more hardware space and transmission bandwidth. This paper introduces a new lossless compression method which reduces the size of the image by performing on blocks that have the comparable color components because the importance of the color varies from block to block depending upon the image. The similar color blocks are identified by the histogram values of each color Red, Green and Blue. A threshold value is fixed and the high order color component blocks will be removed and mentioned in a frequency table. While using this method, we got a comparatively better compression ratio for satellite images than the existing compression methods.
 
Phytochemical investigation, antibacterial and antioxidant activities of Sideritis incana L extracts
No full textAccording to the phytochemical investigation conducted on the Sideritis incana L. plant, it was found to be rich in secondary metabolites, in particular tannins, flavonoids and alkaloids, based on what we found by preliminary tests for chemical constituents. The content of phenols, flavonoids was estimated by spectrophotometric methods. Also, the antioxidant activities of the extracts of Sideritis incana L were investigated by DPPH scavenging, and phosphomolybdenum method. The results of the quantitative estimation of total phenols showed the highest content in chloroform where it was estimated 585.64 mg GAE /g followed by n-butanol 282.22 mg GAE /g and the lowest content recorded in petroleum ether 17.32 mg GAE /g. The results of the quantitative evaluation of flavonoids showed that petroleum ether fraction contained an excess of flavonoids in the unusual results. For the DPPH assay, n-butanol fraction showed the best result followed by the ethyl acetate fraction and finally chloroform fraction the lowest activities ( IC50 = 0.0534, 0.071 and 0.0756 μg/ml) respectively. Finally, result of antibacterial activity of S.incana showed that the chloroform extract gave the highest diameter inhibition among all extracts (13 mm) at a concentration of 50 mg/ml against Escherichia coli ATCC25921 and Staphylococcus aureus ATCC25923.
 
Mapping and monitoring of Large-Sfax wetlands (center-east of Tunisia) using radiometric indexes and GIS tools
No full textWetlands are characterized by temporary alterations in their structure and composition, and by multifunctionality. Therefore, identifying the boundaries of these zones is essential for appropriate characterization. In this context, this applied research work focuses on the wetlands of Large Sfax in the eastern center of Tunisia. The adopted methodology is based on a combined approach based on multivariate analysis and multi-dates analysis for the identification and the spatial delimitation of wetlands in the study area. The radiometric indexes of humidity NDWI, vegetation NDVI and brightness IB were calculated for the years 2003 and 2015 by using satellite imagery coming from Landsat ETM+7 and Landsat OLI 8. The classification maps of the calculated indexes enabled the identification and spectral delimitation of the wetlands of the study area. The multi-dates analysis was based on the visual interpretation of the panchromatic aerial photographs and the Google Earth snippets for the update of the results. This allowed the spatial delineation and the monitoring of marine, inland, and artificial wetlands in the study area. The importance of using the combined approach is that it allows a better characterization of wetlands.