Search results for: Mohamed Ahmed Ali

Authors: Kafi Razzaq Ahmed

Abstract:

Speaking fluently in a second language requires vocabulary, grammar, and pronunciation skills. Teaching the English language entails teaching pronunciation. In professional literature, there have been a lot of attempts to integrate technology into improving the pronunciation of learners. The technique is also neglected in Kurdish contexts, Salahaddin University – Erbil included. Thus, the main aim of the research is to point out the efficiency of using video materials for both language teachers and learners within and beyond classroom learning and teaching environments to enhance student's pronunciation. To collect practical data, a research project has been designed. In subsequent research, a posttest will be administered after each lesson to 100 first-year students at Salahaddin University-Erbil English departments. All students will be taught the same material using different methods, one based on video materials and the other based on the traditional approach to teaching pronunciation. Finally, the results of both tests will be analyzed (also knowing the attitudes of both the teachers and the students about both lessons) to indicate the impact of using video in the process of teaching and learning pronunciation.

Keywords: video, pronunciation, teaching, learning

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Authors: Zakaria Aketouane, Mustapha Malha, Abdellah Bah, Omar Ansari, Mohamed Asbik

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The present paper deals with the thermal performance of a hollow-brick filled with Phase Change Material (PCM). The main objective is to study the effect of percentage and melting temperature of the PCM on the thermal inertia and internal surface temperature of the hollow-brick. A numerical model based on the heat transfer equation and the apparent heat capacity method has been validated using experimental study from the literature. The results show that increasing the percentage of the PCM has a significant effect on time lag and decrement factor that define the thermal inertia; the internal temperature is reduced by 1.36°C to 5.39°C for a percentage from 11% to 71% in comparison to a brick without PCM. In addition, an appropriate melting temperature of 37°C has been deduced for the horizontal wall orientation in Rabat in comparison to 27°C and 47°C.

Keywords: appropriate melting temperature, decrement factor, phase change material, thermal inertia, time lag

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Authors: Hussein M. Maghrabie, M. Attalla, Hany. A. Mohamed, M. Salem, E. Specht

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An experimental investigation is carried out on counter-flow Ranque–Hilsch vortex tube (RHVT). The present work is carried out to study the effect of nozzle aspect ratio, tube length and the inlet pressure (P_i) on the coefficient of performance and energy separation of a RHVT. Further, the effect of moist air with different relative humidity (RH) 40, 60, 80 % is also achieved. The air relative humidity is adjusted using air humidification/dehumidification unit. The experimental study accomplished for number of nozzle N=6, with inner diameter D=7.5 mm., and length of the vortex tube (L) 75, 97.5, and 112.5 mm. The results show that the relative humidity has a significant effect on coefficient of performance and energy separation of a RHVT.

Keywords: COP, counter-flow Ranque–Hilsch vortex tube, energy separation, humid air

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Authors: Yousif M. Yousif Abdallah, Mohamed E. Gar-Elnabi, Abdoelrahman H. A. Bakary, Alaa M. H. Eltoum, Abdelazeem K. M. Ali

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The study was established to measure the amount of radiation outside the treatment field in external beam radiation therapy using day method of dose calculation, the data was collected from 89 patients of cervical carcinoma in order to determine if the dose outside side the irradiation treatment field for spleen, liver, both kidneys, small bowel, large colon, skin within the acceptable limit or not. The cervical field included mainly 4 organs which are bladder, rectum part of small bowel and hip joint these organ received mean dose of (4781.987±281.321), (4736.91±331.8), (4647.64±387.1) and (4745.91±321.11) respectively. The mean dose received by outfield organs was (77.69±15.24cGy) to large colon, (93.079±12.31cGy) to right kidney (80.688±12.644cGy) to skin, (155.86±17.69cGy) to small bowel. This was more significant value noted.

Keywords: radiation dose, cervical carcinoma, day’s methods, radiation medicine

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Authors: Mohamed A. Morsy, Azza A. K. El-Sheikh, Abdulla Y. Al-Taher

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The aim of the present study is to investigate the effect of resveratrol (RES) on methotrexate (MTX)-induced testicular damage. RES (10 mg/kg/day) was given for 8 days orally and MTX (20 mg/kg i.p.) was given at day 4 of experiment, with or without RES in rats. MTX decreased serum testosterone, induced histopathological testicular damage, increased testicular tumor necrosis factor-α level and expression of nuclear factor-κB and cyclooxygenase-2. In MTX/RES group, significant reversal of these parameters was noticed, compared to MTX group. Testicular expression of multidrug resistance protein (Mrp) 3 was three- and five-folds higher in RES- and MTX/RES-treated groups, respectively. In vitro, using prostate cancer cells, each of MTX and RES alone induced cytotoxicity with IC50 0.18 ± 0.08 and 20.5 ± 3.6 µM, respectively. RES also significantly enhanced cytotoxicity of MTX. In conclusion, RES appears to have dual beneficial effect, as it promotes MTX tumor cytotoxicity, while protecting the testes, probably via up-regulation of testicular Mrp3 as a novel mechanism.

Keywords: resveratrol, methotrexate, multidrug resistance protein 3, tumor necrosis factor-α, nuclear factor-κB, cyclooxygenase-2

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Authors: Nora Yusma Bte Mohamed Yusoff, Hussain Ali Bekhet

Abstract:

The rationalization of a gradual subsidies reforms plan has been set out by the Malaysian government to achieve the high-income nation target. This paper attempts to analyze the impacts of energy subsidy reform policy on fiscal deficit and macroeconomics variables in Malaysia. The Computable General Equilibrium (CGE) Model is employed. Three simulations based on different groups of scenarios have been developed. Importantly, the overall results indicate that removal of fuel subsidy has significantly improved the real GDP and reduced the government fiscal deficit. On the other hand, the removal of the fuel subsidy has increased most of the local commodity prices, especially energy commodities. The findings of the study could provide some imperative inputs for policy makers, especially to identify the right policy mechanism. This is especially ensures the subsidy savings from subsidy removal could be transferred back into the domestic economy in the form of infrastructure development, compensation and increases in others sector output contributions towards a sustainable economic growth.

Keywords: CGE, deficit, energy, reform, subsidy

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Authors: Morsy Ahmed Morsy Ismail

Abstract:

In this paper, the structure of a coherent homodyne receiver for the Binary Phase Shift Keying (BPSK) Optical Code Division Multiple Access (OCDMA) network is introduced based on the Multi-Length Weighted Modified Prime Code (ML-WMPC) for multimedia applications. The Bit Error Rate (BER) of this homodyne detection is evaluated as a function of the number of active users and the signal to noise ratio for different code lengths according to the multimedia application such as audio, voice, and video. Besides, the Mach-Zehnder interferometer is used as an external phase modulator in homodyne detection. Furthermore, the Multiple Access Interference (MAI) and the receiver noise in a shot-noise limited regime are taken into consideration in the BER calculations.

Keywords: OCDMA networks, bit error rate, multiple access interference, binary phase-shift keying, multimedia

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Authors: Naveed Ahmed Khan

Abstract:

The ever increasing importance of food industry cannot be denied and especially in the wake of escalating population and prices both in developing and developed nations. Thus, this issue demands the attention of researchers especially in the area of supply chain to identify cost diminution waste eliminating supply chain practices in the said industry. For such purpose the 'Dairy Division' of Engro Foods Limited, one of the biggest food companies in Pakistan was taken into consideration in a case study manner. Based on the literature review and interviews following variables were obtained: energy, losses, maintenance, taxes, and logistics. Having studied the said variables, it was concluded that management of relevant industries operating in a comparable environment need to efficiently manage two major areas: energy and taxes. On the other hand, similar kind of other organizations could be benefited by adopting the proficient supply chain practices being observed at dairy division of Engro foods limited.

Keywords: cost diminution, supply chain, dairy industry, Engro Foods Limited

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Authors: Nasir Baba Ahmed, Nicolas Daclin, Marc Olivaux, Gilles Dusserre

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The Mobile field hospital is critical in terms of managing emergencies in crisis. It is a sub-section of the main hospitals and the health sector, tasked with delivering responsive, immediate, and efficient medical services during a crisis. With the aim to prevent further crisis, the assessment of the cyber assets follows different methods, to distinguish its strengths and weaknesses, and in turn achieve cyber resiliency. The work focuses on assessments of cyber resilience in field hospitals with trends growing in both the field hospital and the health sector in general. This creates opportunities for the adverse attackers and the response improvement objectives for attaining cyber resilience, as the assessments allow users and stakeholders to know the level of risks with regards to its cyber assets. Thus, the purpose is to show the possible threat vectors which open up opportunities, with contrast to current trends in the assessment of the mobile field hospitals’ cyber assets.

Keywords: assessment framework, cyber resilience, cyber security, mobile field hospital

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Authors: Naima Ikken, Abdelhadi Bouknadel, Nour-eddine Tariba Ahmed Haddou, Hafsa El Omari

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The operation of grid-connected inverters necessity a single-phase phase locked loop (PLL) is proposed in this article to accurately and quickly estimate and detect the grid phase angle. This article presents the improvement of a method of phase-locked loop. The novelty is to generate a method (PLL) of synchronizing the grid with a Notch filter based on adaptive fuzzy logic for inverter systems connected to the grid. The performance of the proposed method was tested under normal and abnormal operating conditions (amplitude, frequency and phase shift variations). In addition, simulation results with ISPM software are developed to verify the effectiveness of the proposed method strategy. Finally, the experimental test will be used to extract the result and discuss the validity of the proposed algorithm.

Keywords: phase locked loop, PLL, notch filter, fuzzy logic control, grid connected inverters

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Authors: Ahmed El-Ghorab

Abstract:

Indigenous foods are promising sources of various chemical bioactive compounds such as vitamins, phenolic compounds and carotenoids. Therefore, the presence o different bioactive compounds in fruits could be used to retard or prevent various diseases such as cardiovascular and cancer. This is an update report on nutritional compositions and health promoting phytochemicals of different indigenous food . This different type of fruits and/ or other sources such as spices, aromatic plants, grains by-products, which containing bioactive compounds might be used as functional foods or for nutraceutical purposes. most common bioactive compounds are vitamin C, polyphenol, β- carotene and lycopene contents. In recent years, there has been a global trend toward the use of natural phytochemical as antioxidants and functional ingredients, which are present in natural resources such as vegetables, fruits, oilseeds and herbs.. Our future trend the Use of Natural antioxidants as a promising alternative to use of synthetic antioxidants and the Production of natural antioxidant on commercial scale to maximize the value addition of indigenous food waste as a good source of bioactive compounds such as antioxidants.

Keywords: bioactive compounds, antioxidants, by-product, indigenous foods, phenolic compounds

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Authors: Ahmed M. Alavi

Abstract:

India is the motherland of countless beliefs and religious traditions. Hinduism is one of the oldest traditions of India and owns the treasure of numerous organic and inorganic gods. Hinduism was unfamiliar of the manifestation of divine powers in its early accounts. The conceptualization of the divine powers is still debatable query among the experts of the area. This study examines the unseen memoirs of the Hindu god concept and answers the dubious question ‘how Hindu gods subjected to manifestation? Comparing the attitude of the Hindu and Asiatic tantric traditions; these study hypotheses the clear role of tantric Bhakti movements which originated in 3rd to 5th century BC in south India as the key of the conceptualization. The study concludes exploring the vital role of Bhakti movement in rifting the Indian Hindu community to three major fans of manifested gods; the Shaivism, Vishnavism and Saktism and spreading the new trend all over the sub-continent.

Keywords: Bhakti movement, concept of manifestation of divine object, Hindu god concept, Tantrism

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Authors: Safiah Ahmed Madkhali

Abstract:

The grammatical relation object has not attracted the same attention in the literature as subject has. Where there is a clearly monotransitive verb such as kick, the criteria for identifying the grammatical relation may converge. However, the term object is also used to refer to phenomena that do not subsume all, or even most, of the recognized properties of the canonical object. Instances of such phenomena include non-canonical objects such as the ones in the so-called double-object construction i.e. the indirect object and the direct object as in (He bought his dog a new collar). In this paper, it is demonstrated how criteria of identifying the grammatical relation object that are found in the theoretical and typological literature can be applied to Arabic. Also, further language-specific criteria are here derived from the regularities of the canonical object in the language. The criteria established in this way are then applied to the non-canonical objects to demonstrate how far they conform to, or diverge from, the canonical object. Contrary to the claim that the direct object is more similar to the canonical object than is the indirect object, it was found that it is, in fact, the indirect object rather than the direct object that shares most of the aspects of the canonical object in monotransitive clauses.

Keywords: canonical objects, double-object constructions, cognate object constructions, non-canonical objects

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Authors: Ahmed Shuhaiber

Abstract:

The explosion of the World Wide Web and the electronic trend of university teaching have transformed the learning style to become more learner-centred, Which has popularized the digital delivery of mediated lectures as an alternative or an adjunct to traditional lectures. Despite its potential and popularity, virtual lectures have not been adopted yet in Jordanian universities. This research aimed to fill this gap by studying the factors that influence student’s willingness to accept virtual lectures in one Jordanian University. A quantitative approach was followed by obtaining 216 survey responses and statistically applying the UTAUT model with some modifications. Results revealed that performance expectancy, effort expectancy, social influences and self-efficacy could significantly influence student’s attitudes towards virtual lectures. Additionally, facilitating conditions and attitudes towards virtual lectures were found with significant influence on student’s intention to take virtual lectures. Research implications and future work were specified afterwards.

Keywords: E-learning, student willingness, UTAUT, virtual Lectures, web-based learning systems

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Authors: Mohamed Ramdani, Hassen Abdellaoui, Abdenour Boudrassen

Abstract:

Mobile platform’s attitude estimation approaches mainly based on combined positioning techniques and developed algorithms; which aim to reach a fast and accurate solution. In this work, we describe the design and the implementation of an attitude determination (AD) process, using only measurements from GPS sensors. The major issue is based on smoothed GPS code data using Hatch filter and raw carrier-phase measurements integrated into attitude algorithm based on vectors measurement using least squares (LSQ) estimation method. GPS dataset from a static experiment is used to investigate the effectiveness of the presented approach and consequently to check the accuracy of the attitude estimation algorithm. Attitude results from GPS multi-antenna over short baselines are introduced and analyzed. The 3D accuracy of estimated attitude parameters using smoothed measurements is over 0.27°.

Keywords: attitude determination, GPS code data smoothing, hatch filter, carrier-phase measurements, least-squares attitude estimation

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Authors: Irfan Ali, Srikant Gupta, Aquil Ahmed

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Every country needs a sustainable development (SD) for its economic growth by forming suitable policies and initiative programs for the development of different sectors of the country. This paper is comprised of modeling and optimization of different sectors of India that form a multi-criterion model. In this paper, we developed a fractional goal programming (FGP) model that helps in providing the efficient allocation of resources simultaneously by achieving the sustainable goals in gross domestic product (GDP), electricity consumption (EC) and greenhouse gasses (GHG) emission by the year 2030. Also, a weighted model of FGP is presented to obtain varying solution according to the priorities set by the policy maker for achieving future goals of GDP growth, EC, and GHG emission. The presented models provide a useful insight to the decision makers for implementing strategies in a different sector.

Keywords: sustainable and economic development, multi-objective fractional programming, fuzzy goal programming, weighted fuzzy goal programming

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Authors: Mohamed Adnan Landolsi, Ali F. Almutairi

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The paper addresses the problem of line-of-sight (LOS) vs. non-line-of-sight (NLOS) propagation link identification in ultra-wideband (UWB) wireless networks, which is necessary for improving the accuracy of radiolocation and positioning applications. A LOS/NLOS likelihood hypothesis testing approach is applied based on exploiting distinctive statistical features of the channel impulse response (CIR) using parameters related to the “skewness” of the CIR and its root mean square (RMS) delay spread. A log-normal fit is presented for the probability densities of the CIR parameters. Simulation results show that different environments (residential, office, outdoor, etc.) have measurable differences in their CIR parameters’ statistics, which is then exploited in determining the nature of the propagation channels. Correct LOS/NLOS channel identification rates exceeding 90% are shown to be achievable for most types of environments. Additional improvement is also obtained by combining both CIR skewness and RMS delay statistics.

Keywords: UWB, propagation, LOS, NLOS, identification

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Authors: Abida Haddouche, Ahmed Chrif Toubal

Abstract:

The Neogene basin of the Eastern Mitidja, object of the study area, represents potential water resources and especially groundwater reserves. This water is an important economic; this resource is highly sensitive which need protection and preservation. Unfortunately, these waters are exposed to various forms of pollution, whether from urban, agricultural, industrial or merely accidental. This pollution is a permanent risk of limiting resource. In this context, the work aims to evaluate the intrinsic vulnerability of the aquifer to protect and preserve the quality of this resource. It will focus on the disposal of water and land managers a cartographic document accessible to locate the areas where the water has a high vulnerability. Vulnerability mapping of the Easter Mitidja quaternary aquifer is performed by applying three methods (DRASTIC, DRIST, and GOD). Comparison and validation results show that the DRASTIC method is the most suitable method for aquifer vulnerability of the study area.

Keywords: Aquifer of Mitidja, DRASTIC method, geographic information system (GIS), vulnerability mapping

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Authors: Hamza Assiry, Gamal A. Mohamed, Sabrin R. M. Ibrahim, Hossam M. Abdallah

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Chemical investigation of the aerial parts of Barleria trispinosa(Forssk.) Vahl. resulted in isolation of four major iridoids that were identified as 6,8-O,O-diacetylshanhiside methyl ester (acetyl barlerin) (1), 8-O-acetylshanzhiside methyl ester (barlerin) (2), shanzhiside methyl ester (3), and 6- ⍺ -L-rhamnopyranosyl-8-O-acetylshanzihiside methyl ester (4). The isolated compounds were confirmed by detailed one and two-dimensional NMR. Isolated compounds were tested for their cytotoxic activity on breast cancer (MCF-7, MDA-MB-231) and colon cancer (LS174T) cell linesusing sulphorhodamine B (SRB) assay. It is noteworthy that compound 1 demonstrated a significant cytotoxic potential towards MDA-MB-231 cell line with IC5016.7 ± 2.7µg / mL compared to doxorubicin whereas compounds 2, showed moderate cytotoxic potential with IC5021.2 ± 1.9µg / mL on MCF-7. The other compounds showed moderate activity on the tested cell lines.

Keywords: acanthaceae, cytotoxicity, metabolites, barleria trispinosa

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Authors: Muhammad Khairul Anuar Mohamed, Mohd Zuki Salleh, Anuar Ishak, Nor Aida Zuraimi Md Noar

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In this study, the numerical investigation of viscous dissipation on convective boundary layer flow towards a horizontal circular cylinder with constant wall temperature is considered. The transformed partial differential equations are solved numerically by using an implicit finite-difference scheme known as the Keller-box method. Numerical solutions are obtained for the reduced Nusselt number and the skin friction coefficient as well as the velocity and temperature profiles. The features of the flow and heat transfer characteristics for various values of the Prandtl number and Eckert number are analyzed and discussed. The results in this paper is original and important for the researchers working in the area of boundary layer flow and this can be used as reference and also as complement comparison purpose in future.

Keywords: free convection, horizontal circular cylinder, viscous dissipation, convective boundary layer flow

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Authors: A. A. A. Aboalnour, Ahmed M. Amasaib, Mohammed-Almujtaba A. Mohammed-Farah, Abdelhakam, A. Noreldien

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This paper presents a design and study of Parabolic Trough Solar Collector (PTC). Mathematical models were used in this work to find the direct and reflected solar radiation from the air layer on the surface of the earth per hour based on the total daily solar radiation on a horizontal surface. Also mathematical models had been used to calculate the radiation of the tilted surfaces. Most of the ingredients used in this project as previews data required on several solar energy applications, thermal simulation, and solar power systems. In addition, mathematical models had been used to study the flow of the fluid inside the tube (receiver), and study the effect of direct and reflected solar radiation on the pressure, temperature, speed, kinetic energy and forces of fluid inside the tube. Finally, the mathematical models had been used to study the (PTC) performances and estimate its thermal efficiency.

Keywords: CFD, experimental, mathematical models, parabolic trough, radiation

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Authors: Assma Azeroual, Karim Afdel, Mohamed El Hajji, Hassan Douzi

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Key frame extraction methods select the most representative frames of a video, which can be used in different areas of video processing such as video retrieval, video summary, and video indexing. In this paper we present a novel approach for extracting key frames from video sequences. The frame is characterized uniquely by his contours which are represented by the dominant blocks. These dominant blocks are located on the contours and its near textures. When the video frames have a noticeable changement, its dominant blocks changed, then we can extracte a key frame. The dominant blocks of every frame is computed, and then feature vectors are extracted from the dominant blocks image of each frame and arranged in a feature matrix. Singular Value Decomposition is used to calculate sliding windows ranks of those matrices. Finally the computed ranks are traced and then we are able to extract key frames of a video. Experimental results show that the proposed approach is robust against a large range of digital effects used during shot transition.

Keywords: FSDWT, key frame extraction, shot detection, singular value decomposition

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Authors: Nour El Houda Arabi, Aicha Iratni, Talaighil Razika, Bruno Capoen, Mohamed Bouazaoui

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In this paper, we report the effect of the calcination temperature and SiO2 addition on structural, optical and hydrophilicity of TiO2 films deposited by deep-coating sol-gel process. XRD investigation of the structural TiO2 films with increasing the temperature calcination, reveals that rutile phase will appear for the high temperature (>1000°C). However, the addition of SiO2 relate the densification of TiO2 films. Ellipsometric and UV-visible measure show that the refractive index grow with increasing temperature, against the film thickness decreases. On the other hand, the addition of SiO2 decreases the refractive index and increases the TiO2 film thickness. Finally, the hydrophilicity is assisted by contact angle measurement. It is found that addition of 50% of SiO2 to TiO2 is most effective for reducing the contact angle of water.

Keywords: physical properties, sol, gel, TiO2/SiO2 composite films

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Authors: Rahal Nacer, Beghdad Houda, Tehami Mohamed, Souici Abdelaziz

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Although the shrinkage of the concrete causes undesirable parasitic effects to the structure, it can then harm the resistance and the good appearance of the structure. Long term behaviourmodelling of steel-concrete composite beams requires the use of the time variable and the taking into account of all the sustained stress history of the concrete slab constituting the cross section. The work introduced in this article is a theoretical study of the behaviour of composite beams with respect to the phenomenon of concrete shrinkage. While using the theory of the linear viscoelasticity of the concrete, and on the basis of the rate of creep method, in proposing an analytical model, made up by a system of two linear differential equations, emphasizing the effects caused by shrinkage on the resistance of a steel-concrete composite beams. Results obtained from the application of the suggested model to a steel-concrete composite beam are satisfactory.

Keywords: composite beams, shrinkage, time, rate of creep method, viscoelasticity theory

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Authors: Mohamed M. Bumadian, D. James Gilmour

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Three bacterial species were isolated from the River Wye (Derbyshire, England) and identified using 16S rRNA gene sequencing as Serratia proteamaculans, Aeromonas hydrophila and Klebsiella pneumoniae. Respiration rates of the strains were measured in order to determine the metabolic activity under salt stress. The highest respiration rates of all three strains were found at 0.17 M and 0.5 M NaCl and then the respiration rate decreased with increasing concentrations of NaCl. In addition, the effect of increasing concentrations of NaCl on malate dehydrogenase activity was determined using cell-free extracts of the three strains. Malate dehydrogenase activity was stimulated at NaCl concentrations up to 0.5 M, and a small level of activity remained even at 3.5 M NaCl. The pH optimum of the malate dehydrogenase in cell-free extracts of all strains was higher than pH 7.5.

Keywords: fresh water, halotolerant pathogenic bacteria, 16S rRNA gene, cell-free extracts, respiration rates, malate dehydrogenase

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Authors: Rehab Abdulmajed, Amr Hamada, Ahmed Elsaid, Hisashi Hayakawa, Ayman Mahrous

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Solar emissions have a high impact on the Earth’s magnetic field, and the prediction of solar events is of high interest. Various techniques have been used in the prediction of solar wind using mathematical models, MHD models, and neural network (NN) models. This study investigates the coronal hole (CH) derived high-speed streams (HSSs) and their correlation to the CH area and create a neural network model to predict the HSSs. Two different algorithms were used to compare different models to find a model that best simulates the HSSs. A dataset of CH synoptic maps through Carrington rotations 1601 to 2185 along with Omni-data set solar wind speed averaged over the Carrington rotations is used, which covers Solar cycles (sc) 21, 22, 23, and most of 24.

Keywords: artificial neural network, coronal hole area, feed-forward neural network models, solar high speed streams

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Authors: Amel Boulemtafes-Boukadoum, Ahmed Benzaoui

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Solar air heaters (SAH) are widely used in heating and drying applications using solar energy. Their efficiency needs to be improved to be competitive towards solar water heater. In this work, our goal is to study heat transfer enhancement in SAHs by the use of artificial roughness on the absorber. For this purpose, computational fluid dynamics (CFD) simulations were carried out to analyze the flow and heat transfer in the air duct of a solar air heater provided with transverse ribs. The air flows in forced convection and the absorber is heated with uniform flux. The effect of major parameters (Reynolds number, solar radiation, air inlet temperature, geometry of roughness) is examined and discussed. To highlight the effect of artificial roughness, we plotted the distribution of the important parameters: Nusselt number, friction factor, global thermohydraulic performance parameter etc. The results obtained are concordant to those found in the literature and shows clearly the heat transfer enhancement due to artifical roughness.

Keywords: solar air heater, artificial roughness, heat transfer enhancement, CFD

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Authors: Chebbah Kaoutar, Marchioni Eric, Menad Ahmed, Mekkiou Ratiba, Sarri Djamel, Ameddah Souad, Boumaza Ouahiba, Seghiri Ramdane, Benayache Samir, Benayache Fadila

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This study was designed to estabilish a preliminary phytochemical screening, evaluate the phenolic and flavonoid content according to the Folin-Ciocalteu procedure, and aluminum chloride method respectively and to determine qualitatively, using HPLC-UV method, the most important products present in ethyl acetate (EtOAc) and n-butanol (n-BuOH) extracts of the aerial parts of Genista cephalantha Spach. from East Algeria. The antioxidant activity of these extracts was spectrophotometrically tested by measuring their ability to scavenge a stable DPPH free radical and by β-Carotene/linoleic acid bleaching assay. Evaluated extracts showed a good activity in both antioxidant system assays.

Keywords: phenolic compounds, flavonoids, HPLC-DAD-UV, antioxidant activity, genista cephalantha, fabaceae

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Authors: Mohammad Javad Maghsoudi, Z. Mohamed, A. R. Husain

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Input shaping has been utilized for vibration reduction of many oscillatory systems. This paper presents an optimal closed-loop input shaping scheme for control of a three dimensional (3D) gantry crane system including. This includes a PID controller and Zero Vibration shaper which consider two control objectives concurrently. The control objectives are minimum sway of a payload and fast and accurate positioning of a trolley. A complete mathematical model of a lab-scaled 3D gantry crane is simulated in Simulink. Moreover, by utilizing PSO algorithm and a proposed scheme the controller is designed to cater both control objectives concurrently. Simulation studies on a 3D gantry crane show that the proposed optimal controller has an acceptable performance. The controller provides good position response with satisfactory payload sway in both rail and trolley responses.

Keywords: 3D gantry crane, input shaping, closed-loop control, optimal scheme, PID

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Authors: Mohamed E. Eleshaky

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This paper investigates the dynamic behavior of laminar water flows inside superhydrophobic micro-pipes patterned with square micro-posts features under different operating conditions. It also investigates the effects of air fraction and Reynolds number on the frictional performance of these pipes. Rather than modeling the air-water interfaces of superhydrophobic as a flat inflexible surface, a transient, incompressible, three-dimensional, volume-of-fluid (VOF) methodology has been employed to continuously track the air–water interface shape inside micro-pipes. Also, the entrance effects on the flow field have been taken into consideration. The results revealed the strong dependency of the frictional performance on the air fractions and Reynolds number. The frictional resistance reduction becomes increasingly more significant at large air fractions and low Reynolds numbers. Increasing Reynolds number has an adverse effect on the frictional resistance reduction.

Keywords: drag reduction, laminar flow in micropipes, numerical simulation, superhyrophobic surfaces, microposts

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