Condition Monitoring of photovoltaic systems plays an important role in maintenance interventions due to its ability to solve problems of loss of energy production revenue. Nowadays, machine learning-based failure diagnosis is becoming increasingly growing as an alternative to various difficult physical-based interpretations and the main pile foundation for condition monitoring. As a result, several methods with different learning paradigms (e.g. deep learning, transfer learning, reinforcement learning, ensemble learning, etc.) have been used to address different condition monitoring issues. Therefore, the aim of this paper is at least, to shed light on the most relevant work that has been done so far in the field of photovoltaic systems machine learning-based condition monitoring.
Condition Monitoring of photovoltaic systems plays an important role in maintenance interventions due to its ability to solve problems of loss of energy production revenue. Nowadays, machine learning-based failure diagnosis is becoming increasingly growing as an alternative to various difficult physical-based interpretations and the main pile foundation for condition monitoring. As a result, several methods with different learning paradigms (e.g. deep learning, transfer learning, reinforcement learning, ensemble learning, etc.) have been used to address different condition monitoring issues. Therefore, the aim of this paper is at least, to shed light on the most relevant work that has been done so far in the field of photovoltaic systems machine learning-based condition monitoring.
To ensure the continuity of electric power generation for photovoltaic systems, condition monitoring frameworks are subject to major enhancements. The continuous uniform delivery of electric power depends entirely on a well-designed condition maintenance program. A just-in-time task to deal with several naturally occurring faults can be correctly undertaken via the cooperation of effective detection, diagnosis, and prognostic analyses. Therefore, the present review first outlines different failure modes to which all photovoltaic systems are subjected, in addition to the essential integrated detection methods and technologies. Then, data-driven paradigms, and their contribution to solving this prediction problem, are also explored. Accordingly, this review primarily investigates the different learning architectures used (i.e., ordinary, hybrid, and ensemble) in relation to their learning frameworks (i.e., traditional and deep learning). It also discusses the extension of machine learning to knowledge-driven approaches, including generative models such as adversarial networks and transfer learning. Finally, this review provides insights into different works to highlight various operating conditions and different numbers and types of failures, and provides links to some publicly available datasets in the field. The clear organization of the abundant information on this subject may result in rigorous guidelines for the trends adopted in the future.
To ensure the continuity of electric power generation for photovoltaic systems, condition monitoring frameworks are subject to major enhancements. The continuous uniform delivery of electric power depends entirely on a well-designed condition maintenance program. A just-in-time task to deal with several naturally occurring faults can be correctly undertaken via the cooperation of effective detection, diagnosis, and prognostic analyses. Therefore, the present review first outlines different failure modes to which all photovoltaic systems are subjected, in addition to the essential integrated detection methods and technologies. Then, data-driven paradigms, and their contribution to solving this prediction problem, are also explored. Accordingly, this review primarily investigates the different learning architectures used (i.e., ordinary, hybrid, and ensemble) in relation to their learning frameworks (i.e., traditional and deep learning). It also discusses the extension of machine learning to knowledge-driven approaches, including generative models such as adversarial networks and transfer learning. Finally, this review provides insights into different works to highlight various operating conditions and different numbers and types of failures, and provides links to some publicly available datasets in the field. The clear organization of the abundant information on this subject may result in rigorous guidelines for the trends adopted in the future.
We analyzed the influence of land use and water physical-chemical characteristics on the trait composition of benthic macroinvertebrates in arid-land streams of North-East Algeria. Macroinvertebrates were sampled in the spring season of 2015, 2017 and 2018 at 36 sampling sites distributed along 5 streams of the Belezma biosphere reserve. Samples were taken from the various substratum types using a Surber net. Most of the variability of the trait-environment relationship was explained by increasing temperature and conductivity along the downstream gradient. Whilst agriculture at higher elevations did not have a great influence on the functional trait composition of macroinvertebrate communities, agriculture and urbanization at lower elevations generated significant deviations from predictable functional structures. Owing to the natural downstream decrease in community diversity in streams of the study region, entire taxa and/or functional groups were more likely to be wiped out in response to anthropogenic perturbations at lower elevations. Despite human activities, climate-related variables in arid lands play a major role on hydrological regimes that effect instream habitats, water chemistry, and macroinvertebrate communities. Given the environmental constraints in arid-land streams of North Africa, even slight increases in anthropogenic pressure can have negative effects on the taxonomic and functional composition of macroinvertebrate communities.
We analyzed the influence of land use and water physical-chemical characteristics on the trait composition of benthic macroinvertebrates in arid-land streams of North-East Algeria. Macroinvertebrates were sampled in the spring season of 2015, 2017 and 2018 at 36 sampling sites distributed along 5 streams of the Belezma biosphere reserve. Samples were taken from the various substratum types using a Surber net. Most of the variability of the trait-environment relationship was explained by increasing temperature and conductivity along the downstream gradient. Whilst agriculture at higher elevations did not have a great influence on the functional trait composition of macroinvertebrate communities, agriculture and urbanization at lower elevations generated significant deviations from predictable functional structures. Owing to the natural downstream decrease in community diversity in streams of the study region, entire taxa and/or functional groups were more likely to be wiped out in response to anthropogenic perturbations at lower elevations. Despite human activities, climate-related variables in arid lands play a major role on hydrological regimes that effect instream habitats, water chemistry, and macroinvertebrate communities. Given the environmental constraints in arid-land streams of North Africa, even slight increases in anthropogenic pressure can have negative effects on the taxonomic and functional composition of macroinvertebrate communities.
The issue of robustness of stability has been prominent in the literature on control theory over the last two decades. An important state-space approach to robustness analysis is the stability radii theory. The robust stability problems of infinite dimensional systems subjected to stochastic bounded structured perturbations have been studied using the stability radius approach. In the applications it is important to study these problems in the case where the perturbations operator structure are unbounded, because it covers the case of partial differential equations with boundary and ..
In this paper we consider infinite dimensional systems subjected to stochastic structured multiperturbations. We address the problem of robustness optimization with respect to state feedback but allow both unbounded input and perturbations. Conditions are derived for the existence of a stabilizing controller ensuring that the norm of the closed loop operator below a prespecified bound. Such controllers will be called suboptimal controllers. The suboptimality conditions are obtained in terms of a Riccati equation which satisfies an operator inequality. Finally, we give a lower bound for the supremal achievable stability radius via the Riccati equation.
This paper presents the first description of the mcr-5.1 gene in a colistin-resistant Cupriavidus gilardii isolate from well water that supplies a maternity hospital in Algeria. The whole-genome sequence of this strain showed the presence of putative β-lactamase, aac(3)-IVa, and multidrug efflux pump-encoding genes, which could explain the observed multidrug resistance phenotype. Our findings are of great interest, as we highlight a potential contamination route for the spread of mcr genes.
IMPORTANCE Colistin resistance mediated by mcr genes in Gram-negative bacteria has gained significant attention worldwide. This is due to the ability of these genes to be horizontally transferred between different bacterial genera and species. Aquatic environments have been suggested to play an important role in the emergence and spread of this resistance mechanism. Here, we describe the first report of an mcr-5-positive Cupriavidus gilardii aquatic isolate through its isolation from well water in Algeria. The significance of our study is in shedding the light on an important environmental reservoir of mcr genes.
The aim of this work is to study the mechanical behavior of the sediments extracted from the Koudiet Meddaouar, Timgad dam (Algeria), for a possible valorization in the field for building works in order to minimize this phenomenon which is currently a concern for the operators and the persons in charge of the mobilization of the water resources. This siltation therefore severely limits its storage capacity and consequently it’s operating life. The extraction of the sediments accumulated in the dam’s reservoir is therefore imperative, on the pain of seeing it perish in the medium term. These sediments are, however, of great geotechnical and mechanical value. The results of the tests conducted in the laboratory have enabled us to identify the different sediments from a physical and geotechnical point of view In front of the difficulties noted in the control of the silting up of the dams in Algeria, a very important quantity of silt being deposited annually in the dams. In order to achieve our objective, different mixtures of silt with or without lime treatment, cement glass fibers and powdered fibers were studied for the possible manufacture of Compressed Earth Bricks (CEB). The results obtained show that some of the mixtures present very interesting results in the different tests (compression and bending), verifying the conditions of the standards in force and thus allowing their use in the field of the manufacture of building materials.
The aim of this work is to study the mechanical behavior of the sediments extracted from the Koudiet Meddaouar, Timgad dam (Algeria), for a possible valorization in the field for building works in order to minimize this phenomenon which is currently a concern for the operators and the persons in charge of the mobilization of the water resources. This siltation therefore severely limits its storage capacity and consequently it’s operating life. The extraction of the sediments accumulated in the dam's reservoir is therefore imperative, on the pain of seeing it perish in the medium term. These sediments are, however, of great geotechnical and mechanical value. The results of the tests conducted in the laboratory have enabled us to identify the different sediments from a physical and geotechnical point of view In front of the difficulties noted in the control of the silting up of the dams in Algeria, a very important quantity of silt being deposited annually in the dams. In order to achieve our objective, different mixtures of silt with or without lime treatment, cement glass fibers and powdered fibers were studied for the possible manufacture of Compressed Earth Bricks (CEB). The results obtained show that some of the mixtures present very interesting results in the different tests (compression and bending), verifying the conditions of the standards in force and thus allowing their use in the field of the manufacture of building materials.
Le manuel scolaire de fran\c cais langue étrangère est un espace de rencontre de la culture cible et de la propre culture des apprenants. C’est en ce sens qu’il constitue une médiation (inter)culturelle essentielle en didactique des langues-cultures. La médiation dont il est question est surtout linguistique et (inter)culturelle. En tant qu’objet d’enseignement-apprentissage, celle-ci fait partie du socle de compétences (à côté des quatre compétences traditionnelles : compréhension/expression écrites et orales) à développer et à évaluer chez les apprenants de FLE. C’est dans cette perspective que le présent article se propose d’interroger les tâches de médiation linguistique et (inter)culturelle éventuellement présentes dans le manuel de 4e année moyenne. Pour ce faire, nous avons procédé à une analyse descriptive et analytique dudit manuel afin de nous attarder sur la nature des tâches de médiation proposées, leur évolution tout au long du manuel, mais surtout la manière dont la compétence de médiation a été didactisée. L’analyse a révélé que le nombre de tâches de médiation à l’écrit est très limité, et qu’à l’oral, elles sont inexistantes et qu’elles demeurent, de ce fait, loin de favoriser le développement de cette composante essentielle de la compétence (inter)culturelle.
Le manuel scolaire de fran\c cais langue étrangère est un espace de rencontre de la culture cible et de la propre culture des apprenants. C’est en ce sens qu’il constitue une médiation (inter)culturelle essentielle en didactique des langues-cultures. La médiation dont il est question est surtout linguistique et (inter)culturelle. En tant qu’objet d’enseignement-apprentissage, celle-ci fait partie du socle de compétences (à côté des quatre compétences traditionnelles : compréhension/expression écrites et orales) à développer et à évaluer chez les apprenants de FLE. C’est dans cette perspective que le présent article se propose d’interroger les tâches de médiation linguistique et (inter)culturelle éventuellement présentes dans le manuel de 4e année moyenne. Pour ce faire, nous avons procédé à une analyse descriptive et analytique dudit manuel afin de nous attarder sur la nature des tâches de médiation proposées, leur évolution tout au long du manuel, mais surtout la manière dont la compétence de médiation a été didactisée. L’analyse a révélé que le nombre de tâches de médiation à l’écrit est très limité, et qu’à l’oral, elles sont inexistantes et qu’elles demeurent, de ce fait, loin de favoriser le développement de cette composante essentielle de la compétence (inter)culturelle.
In this paper, the Particle Swarm Optimization algorithm (PSO) is combined with Proportional-Derivative (PD) and Proportional-Integral-Derivative (PID) to design more efficient PD and PID controllers for robotic manipulators. PSO is used to optimize the controller parameters Kp (proportional gain), Ki (integral gain) and Kd (derivative gain) to achieve better performances. The proposed algorithm is performed in two steps: (1) First, PD and PID parameters are offline optimized by the PSO algorithm. (2) Second, the obtained optimal parameters are fed in the online control loop. Stability of the proposed scheme is established using Lyapunov stability theorem, where we guarantee the global stability of the resulting closed-loop system, in the sense that all signals involved are uniformly bounded. Computer simulations of a two-link robotic manipulator have been performed to study the efficiency of the proposed method. Simulations and comparisons with genetic algorithms show that the results are very encouraging and achieve good performances.
Various facilities are used in mineral processing to prepare raw material. Practically, two types of balls are used, cast balls and forged balls. They are respectively made from high chromium cast iron and forged steel and are supplied in different sizes and chemical compositions. The cast and forged balls have different microstructures and consequently display dissimilar wear behavior. The target aimed in this work is to achieve a comparative study taking into account the type of microstructure, mechanical properties, and wear behavior of these two kinds of materials. Specimens have undergone chemical, metallographic and XRD characterizations. Subsequently, these samples were subjected to hardness measurements, abrasion and friction tests in order to evaluate their wear behaviour. Tribological tests, under unlubricated environment, are carried out on both types of grinding balls in order to study the wear system. Corrosion tests are also performed on forged steel and high chromium cast iron ball samples. The obtained results reveal a large difference in terms of chemical composition and microstructural components. Chromium cast iron balls are more resistant to friction, whereas forged balls are more resistant to abrasion. Additionally, the corrosion tests reveal a narrow discrepancy in corrosion behaviour between the studied materials.
Miscarriage is defined as an adverse and unexpected termination of pregnancy; it is the most frequent pregnancy complication. Here, we aimed to identify the factors predisposing to miscarriage in pregnant women in Eastern Algeria and the effect of the combination of several factors, including maternal Body Mass Index (BMI), maternal age, concomitant pathologies, and nutrients, and to predict the occurrence of miscarriage.
Methods
A total of 786 pregnant women from Eastern Algeria were interviewed between 2011 and 2015. Association between miscarriage exposure and identified risk factors was assessed using a Generalized Linear Model (GLM), ANOVA test, Multiple Correspondence Analysis (MCA), and Hierarchical Clustering Analysis (HCA). Throughout this study, we sought to find answers, discuss this association, and predict the occurrence of miscarriage.
Results
We developed a predictive model for miscarriage, and we found that miscarriage was significantly higher for pregnant women aged over 35 years (1.75; 95% CI: 0.75–4.37; p = 0.208), with a high BMI (> 25 kg/m2), (1.88; 95% CI:1.28–2.78; p = 0.001). We have highlighted that miscarriage is strongly associated with hypertension (1.67; 95% CI: 1.16–2.39; p = 0.006), diet rich in meat (0.60; 95% CI: 0.33–1.04; p = 0.075), and moderate in fish (2.32; 95% CI: 1.18–4.58; p = 0.015).
Conclusion
Our study proved that knowing these risk factors helps to establish predictive models and strategies to prevent tragic pregnancy outcomes and highlights the link between miscarriage and several risk factors; and thus, will allow protecting mother and fetus health.
As compared to a fixed Photovoltaic (PV) system, a two axis solar tracker system can increase electrical energy production from 35% to 45% in a year. Vibration characteristic is an essential factor in evaluating the reliability and stability of solar tracker structure during operating course. In this paper, the free vibration behaviour (modal analysis) of 12 kW two axis PV solar tracker structure is investigated numerically. The modal analysis by using commercial finite element package (SOLIDWORKS SIMULATION) to identify the modal parameters of the tracker structure (natural frequencies and corresponding modal shapes). The simulation results obtained for tracker structure at maximum elevation angle (60deg) indicate that no resonant problem (according to ASHRAE Standard) during solar tracker operation under wind load (from 0 to 36 m/s).
The behaviour of shallow foundations on slopes is an important topic of interest in geotechnical engineering. This paper presents the results of laboratory model tests of an eccentrically loaded strip footing on a slope. Experiments were conducted with an eccentrically loaded model footing under various eccentricity ratios (±e/B) and normalized footing distances (d/B) and the results were compared with previous literature. The results confirm that the load eccentricity and normalized footing distance have considerable effects on the drained bearing capacity. The ultimate bearing capacity of a negative eccentric load is greater than that of a positive eccentric load up to a relative distance of d/B = 3. At this point, the bearing capacity becomes almost the same regardless of the eccentricity location relative to the slope face. Furthermore, the failure mechanism is not symmetrical; a greater failure surface length can develop on the slope side and this length decreases with increasing eccentricity.
