Preparation and Characterization of Carboxymethyl Cellulose with a High Degree of Substitution from Agricultural Wastes

Ibtissem Moussa,Ramzi Khiari,Ali Moussa,Mohamed Naceur Belgacem,Mohamed Farouk Mhenni 한국섬유공학회 2019 Fibers and polymers Vol.20 No.5

This paper describes the use of agricultural wastes for the preparation of carboxymethylcellulose (CMC) with ahigh degree of substitution using two methods: the classic and a microwave-assisted method. A series of CMC samples withdegrees of substitution from 0.43 to 2.83 were prepared from cellulose extracted from almond shells, almond stems, and figstems by a one-step carboxymethylation reaction. The highest degree of substitution was 2.83, which corresponded to CMCfrom fig stems when butanol was used as a solvent. This CMC was easily dissolved in water and thus would provide manyopportunities for diverse applications. The obtained CMCs were characterized using different tools. Different CMC filmswere prepared using the casting method and were characterized by the determination of their mechanical properties. Theobtained results can be considered promising; they demonstrate the potential of using cellulose derivatives for the productionof transparent and strong films.

Selective Harmonic Elimination in Multi-level Inverters with Series-Connected Transformers with Equal Power Ratings

Moussa, Mona Fouad,Dessouky, Yasser Gaber The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This study applies the selective harmonic elimination (SHE) technique to design and operate a regulated AC/DC/AC power supply suitable for maritime military applications and underground trains. The input is a single 50/60 Hz AC voltage, and the output is a 400 Hz regulated voltage. The switching angles for a multi-level inverter and transformer turns ratio are determined to operate with special connected transformers with equal power ratings and produce an almost sinusoidal current. As a result of its capability of directly controlling harmonics, the SHE technique is applicable to apparatus with congenital immunity to specific harmonics, such as series-connected transformers, which are specially designed to equally share the total load power. In the present work, a single-phase 50/60 Hz input source is rectified via a semi-controlled bridge rectifier to control DC voltage levels and thereby regulate the output load voltage at a constant level. The DC-rectified voltage then supplies six single-phase quazi-square H-bridge inverters, each of which supplies the primary of a single-phase transformer. The secondaries of the six transformers are connected in series. Through off-line calculation, the switching angles of the six inverters and the turns ratios of the six transformers are designed to ensure equal power distribution for the transformers. The SHE technique is also employed to eliminate the higher-order harmonics of the output voltage. A digital implementation is carried out to determine the switching angles. Theoretical results are demonstrated, and a scaled-down experimental 600 VA prototype is built to verify the validity of the proposed system.

Use of Chebyshev Polynomial Kalman Filter for Pseudo-blind Demodulation of CD3S Signals

Moussa Yahia,Valerio Freschi,Davide Radi,Laura Gardini 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5

Chaos based communication represents an attractive solution in order to design secure multiple access digital communication systems. In this paper we investigate the use of piecewise linear chaotic maps as chaotic generators combined, on the receiver side, with Chebyshev Polynomial Kalman Filters in a dual scheme configuration for demodulation purpose. Piecewise linear maps results into enhanced robustness properties of the spreading chaotic sequence, while approximation of nonlinear systems through Chebyshev polynomial series allows closed form estimation of mean and variance. Therefore, statistical moments can be computed by means of simple algebraic operations on matrices in compact form. In this work we extend these concepts to a dual Chebyshev Polynomial Kalman Filter scheme, suitable for signal recovery in chaos based spread spectrum systems. Numerical simulations show that the proposed method achieves lower error levels on a wide range of the bit-energy-tonoise- power-spectral-density ratio with respect to a state-of-the-art method based on unscented Kalman filters.

Thermomechanical analysis of antisymmetric laminated reinforced composite plates using a new four variable trigonometric refined plate theory

Moussa Abualnour,Abdelbaki Chikh,Habib Hebali,Abdelhakim Kaci,Abdeldjebbar Tounsi,Abdelmoumen Anis Bousahla,Abdelouahed Tounsi 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.24 No.6

The thermo-mechanical bending behavior of the antisymmetric cross-ply laminates is examined using a new simple four variable trigonometric plate theory. The proposed theory utilizes a novel displacement field which introduces undetermined integral terms and needs only four variables. The validity of the present model is proved by comparison with solutions available in the literature.

The Effectiveness of Learners’ Preferred and Unpreferred Written Corrective Feedback: A Think-Aloud Study

Moussa Ahmadian,Hooshang Yazdani,Ehsan Mehri 아시아테플 2019 The Journal of Asia TEFL Vol.16 No.2

In early written corrective feedback studies, there were a lot of attempts to test if the feedback types are effective. This study was based on the assumption prevailing in the new era of studies of written corrective feedback, that feedback is effective. Firstly, it aims to compare the think-aloud protocols of the preferred and unpreferred feedback types which were chosen by 20 English learners (10 in preferred, and 10 in unpreferred feedback). To this aim, learners were asked to write diaries for six weeks. In each session, concurrent think-aloud protocols were employed and learners' verbal reports were extracted, and their mental processes were coded through developing a table of mental operations. In the second part of the study, the relative effectiveness of the preferred and unpreferred feedback was measured. Using the Chi-square goodness-of-fit test, the findings of the first part showed a significant difference between the mental operations for each feedback type. The results for the second part suggested that there is a significant difference between the effectiveness of the preferred and unpreferred feedback types. This latter finding indicates that the preferred feedback can facilitate the development of the accuracy in L2 learners' writing more than the unpreferred feedback.

Buckling behavior of a single-layered graphene sheet resting on viscoelastic medium via nonlocal four-unknown integral model

Moussa Bellal,Habib Hebali,Houari Heireche,Abdelmoumen Anis Bousahla,Abdeldjebbar Tounsi,Fouad Bourada,S.R. Mahmoud,E.A. Adda Bedia,Abdelouahed Tounsi 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.5

In the present work, the buckling behavior of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak’s medium is studied using nonlocal four-unknown integral model. This model has a displacement field with integral terms which includes the effect of transverse shear deformation without using shear correction factors. The visco-Pasternak’s medium is introduced by considering the damping effect to the classical foundation model which modeled by the linear Winkler’s coefficient and Pasternak’s (shear) foundation coefficient. The SLGS under consideration is subjected to compressive in- plane edge loads per unit length. The influences of many parameters such as nonlocal parameter, geometric ratio, the visco-Pasternak’s coefficients, damping parameter, and mode numbers on the buckling response of the SLGSs are studied and discussed.

Improving Signal-to-Noise Ratio (SNR) for Inchoate Fault Detection based on Principal Component Analysis (PCA)

Moussa Hamadache,Dongik Lee 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

Detection of inchoate fault demands high level of fault classification accuracy under poor signal-to-noise ratio (SNR) which appears in most industrial environment. Vibration signal analysis methods are widely used for bearing fault detection. In order to guarantee improved performance under poor SNR, feature extraction based on statistical parameters which are free from Gaussian noise become inevitable. This paper proposes a feature extraction framework based on principal component analysis (PCA) for improving SNR. Features extracted based on PCA have the tendency to alleviate the impact of non-Gaussian noise. PCA algorithm provides useful time domains analysis for no-stationary signals such as vibration in which spectral contents vary with respect to time. Experimental studies on vibration caused by ball bearing faults show that the proposed algorithm demonstrates the improvements in term of classification accuracy under poor signal-to-noise ratio (SNR).

Removal of Methylene Blue (MB) in Aqueous Solution by Economic Adsorbent Derived from Apricot Stone Activated Carbon(ASAC)

Moussa Abbas,Mohamed Trari 한국섬유공학회 2020 Fibers and polymers Vol.21 No.4

Quantitative adsorption kinetic and equilibrium parameters for methylene blue (MB) used in the textile industryfrom aqueous solutions were reported in this study using pHPZC and UV-visible absorption spectroscopy. The effects ofadsorbent dosage (1-10 g/l), agitation speed (100-1200 rpm), particule size (63 μm to 2 mm), initial dye concentration (4-15 mg/l), contact time, pH (2-14), and temperature (298-338 K) were determined to find the optimal conditions foradsorption. The FTIR spectroscopy is used to get information on interactions between the adsorbent and MB. The mechanismof adsorption of MB dyeing onto Apricot Stone Activated Carbon (ASAC) was investigated using the pseudo first-order,pseudo second-order kinetic, Elovich and intraparticles diffusion models. The adsorption isotherms of MB onto ASAC aredetermined and correlated with common isotherm equations. The smaller RMSE value obtained for the Langmuir modelindicates the better curve-fitting and the monolayer adsorption capacity of MB is found to be 46.03 mg/g at 25 oC and88.50 mg/g at 70 oC and pH 10. The evaluation of thermodynamics parameters such as the negative free energy ΔGo(+2.70025 to -1.76666 kJ/mol) and positive enthalpy change ΔHo (28.87613 kJ/mol) indicated a spontaneous andendothermic nature of the reaction with chemisorption process. This study in tiny batch gave rise to encouraging results, andwe wish to achieve the adsorption tests in column mode under the real conditions applicable to the treatment of industrialeffluents. The present investigation showed that ASAC is potentially a useful adsorbent for the heavy metals and dyes.

Some Thiosemicarbazide Derivatives as Corrosion Inhibitors for Aluminium in Sodium Hydroxide Solution

Moussa, M.N.,Fouda, A.S.,Taha, F.I.,Elnenaa, A. Korean Chemical Society 1988 Bulletin of the Korean Chemical Society Vol.9 No.4

The effect of some thiosemicarbazide derivatives on corrosion of aluminium in 2M sodium hydroxide has been studied using thermometric, weight loss and hydrogen evolution techniques. The rate of the corrosion depends on the nature of the inhibitor and its concentration, heated of hydrogenation, mode of interaction with the metal surface and formation of metallic complexes. The compounds are weakly adsorbed on the surface of aluminium and form a monolayer of the adsorbate. Values of the Arrhenius activation energies indicate agreement with those obtained for an activation controlled process.

Robust Adaptive Global Time-varying Sliding-mode Control for Finitetime Tracker Design of Quadrotor Drone Subjected to Gaussian Random Parametric Uncertainties and Disturbances

Moussa Labbadi,Mohamed Cherkaoui 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.6

The quadrotor has many potential applications such as infrastructure predictive maintenance in mining tunnels of the railway. In order to navigate through those environments by using the quadrotor drone, there are many challenges such as aerodynamics disturbances, parametric uncertainties, and noise measurements. A robust adaptive global time-varying sliding-mode controller (RAGTVSMC) is proposed to address the quadrotor path in the presence of the random disturbances and uncertainties. In order to eliminate the reaching phase and reduce the initial control effort, a novel time-varying sliding mode (TVSM) surface is presented for the quadrotor system. Moreover, the TVSM surface is designed to meet the impact time requirement with a global sliding mode. Adaptive laws are developed to address the upper bound of the additives disturbances on the quadrotor dynamics using only the error position and velocity. The convergence with specific time is assured and the quadrotor stability is proved according to Lyapunov’s theory. Finally, to demonstrate the effectiveness of the proposed controller in this work,simulations are conducted.