Introduction. Constant increases in power consumption by both industrial and individual users may cause depletion of fossil fuels and environmental pollution, and hence there is a growing interest in clean and renewable energy resources. Photovoltaic power generation systems are playing an important role as a clean power electricity source in meeting future electricity demands.
Problem. All photovoltaic systems have two problems; the first one being the very low electric-power generation efficiency, especially under low-irradiation states; the second resides in the interdependence of the amount of the electric power generated by solar arrays and the ever changing weather conditions. Load mismatch can occur under these weather varying conditions such that maximum power is not extracted and delivered to the load. This issue constitutes the so-called maximum power point tracking problem.
Aim. Many methods have been developed to determine the maximum power point under all conditions. There are various methods, in most of them based on the well-known principle of perturb and observe. In this method, the operating point oscillates at a certain amplitude, no matter whether the maximum power point is reached or not. That is, this oscillation remains even in the steady state after reaching the maximum power point, which leads to power loss. This is an essential drawback of the previous method. In this paper, a cascade sliding mode maximum power point tracking control for a photovoltaic system is proposed to overcome above mentioned problems.
Methodology. The photovoltaic system is mainly composed of a solar array, DC/DC boost converter, cascade sliding mode controller, and an output load. Two sliding mode control design strategies are joined to construct the proposed controller. The primary sliding mode algorithm is designed for maximum power point searching, i.e., to track the output reference voltage of the solar array. This voltage is used to manipulate the setpoint of the secondary sliding mode controller, which is used via the DC-DC boost converter to achieve maximum power output.
Results. This novel approach provides a good transient response, a low tracking error and a very fast reaction against the solar radiation and photovoltaic cell temperature variations. The simulation results demonstrate the effectiveness of the proposed approach in the presence of environmental disturbances.
Introduction. Constant increases in power consumption by both industrial and individual users may cause depletion of fossil fuels and environmental pollution, and hence there is a growing interest in clean and renewable energy resources. Photovoltaic power generation systems are playing an important role as a clean power electricity source in meeting future electricity demands.
Problem. All photovoltaic systems have two problems; the first one being the very low electric-power generation efficiency, especially under low-irradiation states; the second resides in the interdependence of the amount of the electric power generated by solar arrays and the ever changing weather conditions. Load mismatch can occur under these weather varying conditions such that maximum power is not extracted and delivered to the load. This issue constitutes the so-called maximum power point tracking problem.
Aim. Many methods have been developed to determine the maximum power point under all conditions. There are various methods, in most of them based on the well-known principle of perturb and observe. In this method, the operating point oscillates at a certain amplitude, no matter whether the maximum power point is reached or not. That is, this oscillation remains even in the steady state after reaching the maximum power point, which leads to power loss. This is an essential drawback of the previous method. In this paper, a cascade sliding mode maximum power point tracking control for a photovoltaic system is proposed to overcome above mentioned problems.
Methodology. The photovoltaic system is mainly composed of a solar array, DC/DC boost converter, cascade sliding mode controller, and an output load. Two sliding mode control design strategies are joined to construct the proposed controller. The primary sliding mode algorithm is designed for maximum power point searching, i.e., to track the output reference voltage of the solar array. This voltage is used to manipulate the setpoint of the secondary sliding mode controller, which is used via the DC-DC boost converter to achieve maximum power output.
Results. This novel approach provides a good transient response, a low tracking error and a very fast reaction against the solar radiation and photovoltaic cell temperature variations. The simulation results demonstrate the effectiveness of the proposed approach in the presence of environmental disturbances.
Let T ∈ B(H) be a bounded linear operator on a complex Hilbert space H. For n ∈ N, an operator T ∈ B(H) is said to be n-normal if T nT ∗ = T ∗T n. In this paper we investigate a necessary and sufficient condition for the n-normality of ST and T S, where S, T ∈ B(H). As a consequence, we generalize Kaplansky theorem for normal operators to n-normal operators. Also, In this paper, we provide new characterizations of n-normal operators by certain conditions involving powers of Moore-Penrose inverse.
Les pratiques langagières réalisées sur le web, en particulier sur les réseaux sociaux et précisément dans un espace techno-discursif algérien, connaissent une effervescence impressionnante. En effet, une accélération imposante est constatée dans les interactions en ligne. Toutes ces transformations sont le fruit de l’association de la machine et de l’outil informatique aux compétences langagières des internautes. Ces pratiques ont favorisé la possibilité d’aller très vite dans la communication en ligne, ainsi que dans la qualité du message produit qui est de plus en plus proche au message fait dans la communication ordinaire.Language practices carried out on the web, in particular on social networks and precisely in an Algerian techno-discursive space, are experiencing an impressive effervescence. Indeed, an imposing acceleration is observed in online interactions. All these transformations are the result of the association of machines and IT tools with the language skills of Internet users. These practices have favored the possibility of going very quickly in online communication, as well as in the quality of the message produced, which is increasingly close to the message made in ordinary communication.
The aim of this paper is to propose a new family of codes. We define this family over the ring R=∑4s=0vs5A4R=∑s=04v5sA4, with v55=v5v55=v5. We derive its properties, a generator matrix and Gray images. This new family of codes is illustrated by three applications.
Most road crashes at work are caused by Driver Behavioral Drift (DBD). This DBD has become a recurring issue on congested road sections. In this context, this study proposes a method called (MASOCU-DBD) which allows to analyze this DBD problem in two steps: assessment of the dynamics of DBD occurrence using a model called BM-NSA and analysis of DCC using a Cost-Benefit Analysis (CBA) weighted by the Analysis Hierarchical Process (AHP). The application of the MASOCU-DBD on a road section of an Algerian city’s entry highlighted the problem of the DBD in terms of its occurrence and uselessness in the studied section. The merit of the proposed method is that it uses multi-criteria analysis tools (AHP and CBA) as well as a mathematical model (BM-NSA) to analyze professional drivers’ behavioral deviations.
The growth of manufacturing industries and the huge competitive environment forced manufacturing organizations to develop advanced improvement strategies and enhance their sustainability performance. The integration of sustainable Manufacturing in industrial operations leads to enhanced process performances through the reduction of wastes, cost, and environmental impacts and satisfies ergonomic conditions. For this reason, various firms have adopted sustainable manufacturing concepts to enhance their performances and hold a prestigious competitive position. The purpose of this research is to develop an integrated Pythagorean Fuzzy MCDM model to enhance the application process of the conventional Lean Manufacturing approach (LM). Firstly, an extended Value Steam Mapping is proposed to assess the sustainability of the manufacturing process and identify the causes of waste from a sustainability viewpoint. Secondly, Pythagorean Fuzzy Decision-Making Trial And Evaluation Laboratory (PF-DEMATEL) is employed to analyze the interrelationship among the identified. Thirdly, Pythagorean Fuzzy Technique for Order Preference by Similarity to Ideal Solution (PF-TOPSIS) is introduced to prioritize a set of solutions in order to overcome the investigated causes and improve the durability of the manufacturing operations. Finally, sensitivity analysis is conduced to assess the effectiveness of the obtained results. The proposed method has several attractive features. It can address the drawbacks of the conventional LM and enhance its analysis and improvement tasks. However, the proposed approach offers an advanced application process for Lean Manufacturing in a sustainability context. Additionally, the suggested strategy facilitates the leaders to assess the current state of the manufacturing processes and select the appropriate solutions for successful sustainability implementation. The validity of the proposed approach was investigated in a real case study. The results confirm its effectiveness and indicate that using MCDM approaches in LM application process offers a consistent and flexible demarche for sustainable manufacturing implementation.
62 models have been proposed to predict the corrosion inhibition efficiency for a wide variety of organic and inorganic compounds using the statistical analysis. In this context, we used the experimental data of the corrosion inhibition efficiencies of 100 inhibitors (organic and inorganic) as an input data for a statistical analysis in order to determine the most adequate quantitative structure activity relationship (QSAR) models to predict the inhibition efficiency as function of some molecular descriptors. The experimental data used in this study are selected for the corrosion of steel in 0.5 M H2SO4 at 25 °C. Also, we choose the inhibition efficiencies determined by potentiodynamic polarization curves (IEp) and electrochemical impedance spectroscopy (IEEIS). Accordingly, the statistical analysis has been applied to collect the IEp and IEEIS models of corrosion inhibitors. The different models are compared to assess the performance of the best model. Global Performance Indicator (GPI) is computed to evaluate all models. The results show that the cubical model with a GPI of 1.27 is the best (M23) for IEEIS, and the linear model with a GPI of 0.64 for IEp.
The effect of static drying on the physicochemical quality of camel (Camelus dromedarius) meat slices as driedin an oven at 65 ◦C, with the aim of contributing to food safety. During the experiments, meat was cutinto. 8 ± 0.2 cm thick slices, soaked in a saline solution for 30 min, and then dried. Moisture content wasmeasured during the drying phase, and physicochemical parameters, such as protein, ash, sodium, pH, and mineral content, such as calcium (Ca), phosphor (P), magnesium (Mg), potassium (K), zinc (Zn), iron (Fe), copper (Cu) and manganese (Mn), were monitored before and after drying. The colorimetric parametersof the dried samples are also measured. The results show that the physicochemical quality of the dried camelmeat meets the requirements of the Codex Alimentarius Commission. Indeed, the moisture content decreased from 73.94 ± 0.51% to 13.33 ± 0.44%, and the dried food samples were characterized by increases (i) from 19.72 ± 0.30% to 50.97 ± 0.65% in protein content; (ii) from 1.115 ± 0.012% to 4.781 ± 0.047%, in ash content; (iii) from 260 ± 11.7 mg to 1690 ± 32 mg, in the sodium content (for 100 g of dry matter), and (iv) from 5.956 ± 0.087 to 6.203 ± 0.091 in pH value. However, the variation is not significant for all mineral content parameters. Finally, themean values of the colorimetric parameters of brightness (L*), redness (a*), and yellowness (b*) are 37.13 ± 1.64, 22.02 ± 0.72, and 7.73 ± 0.69, respectively (before drying) and they are 25.57 ± 1.56, 9.43 ± 0.78, and 3.74 ± 0.21, respectively (after drying).
A nanometric buried layer of iron disilicide was synthesized by ion implantation in Si(1 1 1) p-type at different temperatures using 195 keV Fe ions with a dose of \(2\).\(10^{17}\)\(Fe^{+}/cm^{2}\). The investigation of the phase composition is carried out by Rutherford backscattering spectrometry (RBS), whereas the structural characterization is obtained by X-ray diffraction (XRD) pole figure. The process of the silicidation has been investigated at a function of the ion implantation temperatures ranging from 200 to 440 °C. The precipitates favor epitaxial growth with respect to Si(1 1 1) planes with epitaxial relationships \( \beta\)-FeSi\(_{2}\)(2 2 0) //Si(1 1 1) and/or \(\beta\)-FeSi\(_{2}\) (2 0 2) // Si(1 1 1).
Notre article tente d’analyser de tout prêt les manuels de 2ème génération en Algérie pour déterminer l’impact de l’algérianisation des textes-supports sur l’objectif interculturel en classe de Fle. Ainsi, notre travail portera sur l’analyse des textes- supports du manuel scolaire officiel de la 4ème année primaire pour voir si ces textes algérianisés demeurent un lieu propice, un espace favorable à la rencontre des cultures et des identités différentes et par ricochet à la concrétisation de la compétence interculturelle.
