Parametric identification of the doubly fed induction machine

International audienceWind Energy is a very promising energy for the future. It is well known that the power delivered by wind turbines directly coupled to the grid is not constant as a result of the wind variability. In the absence of storage systems, a fluctuating power supply produced, can lead to voltage variations in the grid and flicker. Another disadvantage of most induction machines utilized in the wind turbines is that the required reactive power varies with wind speed and time. These problems can make the use of double fed induction generators attractive for wind turbine applications. Doubly-fed induction machines (DFIMs) are beginning to dominate the wind generation market, particularly for the larger sizes of turbine. This work is dedicated to the identification of the parametric double-fed induction machine. We propose a model of the DFIG based on the method of vector space. This model is used to validate the experimental results of identified parameters of the machine. After considering several methods of parameter identification of induction machines, provided with the results of the experiments, we are particularly interested in standardized testing. The proposed approach allows determining the electrical parameters of the machine using conventional methods static and dynamic, mechanical parameters are estimated using a digital channel, following the curve of smoothed experimental slowdown. The identified model parameters are verified by comparing their simulated stator and rotor currents responses against the measured currents. It is again observed that the estimated model responses match the measured responses well

Exhaled breath condensate nitric oxide end products and pH in controlled asthma

AbstractObjectivesAsthma imposes a growing burden on the society in terms of morbidity, quality of life, and healthcare costs. It has the highest morbidity amongst inflammatory lung diseases and its prevalence continues to increase over the world. Inquiry into recent day or nighttime symptoms alone underestimates the burden of asthma and may lead to inadequate treatment of asthma. The aim of the present work is to evaluate the role of nitric oxide (NO) and hydrogen ion concentration (pH) levels in exhaled breath condensate (EBC) in cases of controlled bronchial asthma.Patients and methodsThe present study was conducted on 49 controlled asthmatic patients and 12 control subjects. All patients were subjected to thorough history taking, complete clinical examination and plain postero-anterior chest X-ray. All asthmatics and control subjects were subjected to routine laboratory investigations, spirometric study, EBC collection, processing and analysis for its content of both nitric oxide end products: nitrite and nitrate (NOx) and pH.ResultsAll asthmatics represented Group IT which was further divided into Group Ia: 34 patients on regular inhaled corticosteroid (ICS) therapy and Group Ib: 15 patients on no regular therapy. The control subjects represented Group II. The forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC, peak expiratory flow rate (PEFR) and forced expiratory flow during the middle portion of a forced expiration (FEF 25–75%) were significantly lower in asthmatics than control subjects. The EBC-NOx mean±SD in μmol/L in Group IT (5.99±1.63), in Group Ia (5.27±1.26) and in Group Ib (7.63±1.15) were significantly higher than in Group II (3.66±0.67) with, respectively (p=0.000), (p=0.000) and (p=0.000); and was significantly higher in Group Ib than Group Ia (p=0.000). The EBC-pH mean±SD in Group IT (7.32±0.27), in Group Ia (7.35±0.25) and in Group Ib (7.27±0.3) were significantly lower than in Group II (7.82±0.09) with, respectively (p=0.000), (p=0.000) and (p=0.000); with no significant difference between Group Ia and Group Ib. The EBC-NOx was significantly directly correlated to eosinophils count (p=0.017) and neutrophils count (p=0.002); and inversely correlated to FEV1 (p=0.016), FEV1/FVC (p=0.001), PEFR (p=0.030) and EBC-pH (p=0.003). The EBC-pH was significantly inversely correlated to eosinophils count (p=0.017) and neutrophils count (p=0.036); and directly correlated to FVC (p=0.004), FEV1 (p=0.004) and PEFR (p=0.000).ConclusionEBC-NOx is significantly higher and EBC-pH is significantly lower in asthmatic patients than in control subjects. Asthmatics receiving ICS have a lower EBC-NOx level than those not. EBC-NOx and EBC-pH were significantly correlated and both of them showed significant correlations with spirometric parameters of airway obstruction

Seismic risk assessment for the downtown of the city of Blida, Algeria

Blida (Algeria) is characterized by a high level of seismic exposure and vulnerability due to its dense population and the presence of aging buildings. The historical earthquake that occurred in 1825, with a moment magnitude (Mw7.1), underscored the urgent need for a thorough assessment of seismic risk in the area. Here, an extensive study conducted in downtown of the city of Blida to evaluate seismic risk and its consequences is presented. Geounits 141 and 148 emerged as the most severely affected in all the simulated earthquake scenarios indicating severe damage and casualties mainly for closest earthquakes (Blida and Bounaian, both with moment magnitude Mw7.1) but also for furthest earthquakes as Mouzaia El Affroun (Mw6.6), and Hammam Melouane (Mw.5). The sensitivity analysis demonstrated the importance of the selection of the performance point computation method (improved displacement coefficient method -IDCM, modified capacity spectrum-MADRS, and nonlinear analysis method-N2) and the choice of the ground motion prediction equation. IDCM results are less influenced by the choice of the GMPE, but they provide higher damage results expressed as a mean damage ratio. Moreover, the study estimated potential human impacts in the Blida region, highlighting varying levels of impact on different geounits under different earthquake scenarios. The study's primary findings from seismic risk assessments in the studied region highlight its high susceptibility to earthquakes and can be summarized as follows: The mean damage ratio will be 52.6% ± 1.4%, 50.9% ± 1.6%; 31.8% ± 3.4% and 21.4% ± 3.1% for the Blida, Bounaian, Mouzaia El Affroun and Hammam Melouane earthquakes respectively.We would like to acknowledge the support of the Directorate General for Scientific Research and Technological Development [ N°01/CRAAG/DGRSDT] for their financial assistance in conducting this study

Editorial: current knowledge on pathogenic and endosymbiotic tick-borne bacteria

No abstract available.https://www.frontiersin.org/journals/veterinary-sciencedm2022Zoology and Entomolog

Hydrogeochemical and statistical approach to characterize groundwater salinity in the Ghiss-Nekkor coastal aquifers in the Al Hoceima province, Morocco

Seawater intrusion is one of the most severe problems confronting coastal aquifers. These aquifers are often considered significant freshwater sources, particularly in arid regions. The water resources mobilized at the Al Hoceima (Northeastern Morocco) come from the Ghiss-Nekkor aquifer and the Abdelkarim El Khattabi dam. The degradation of groundwater quality of the aquifer and the probability of marine intrusion has become a severe concern for the communities. The current study provides multidisciplinary research using hydrogeochemical and statistical approaches to evaluate groundwater quality and determine the origin of salinity in this aquifer. Depending on the direction of the water flow, he results indicate that most wells have a total salinity exceeding 2 g/L. The dominant chemical facies encountered are Na-Cl-Na-SO4 resulting from rock-water interaction

The effect of Tecamin Brix-V2 in tomato (Solanum lycopersicum L.) fruit under salt stress

The goal of the present experiment was to evaluate the effect of some biostimulants applications (Tecamin Brix version 2) on the organoleptic quality and production yield parameters of tomato Solanum lycopersicum L. grown under salt stress in the Nador region, Morocco. Climate change is becoming increasingly constraining for plant growth and development, especially in arid and semi-arid areas. These ecosystems are characterized by highly irregular rainfall associated with significant evaporation, which favours the accumulation of salts in the soil. Salt stress is considered in the semi-arid region as a limiting factor affecting crop production and quality. Biostimulants are substances that have the ability to modify plant physiological processes in such a way as to provide potential benefits to growth, development, or stress response. For this purpose, foliar fertilization with Tecamin Brix Version 2 ®, compensates for nutrient deficiency in the roots due to salt stress. The water-soluble fertilizer or a Tecamin brix® Version 2 substance was applied to the foliage to determine the effects on yield and fruit quality parameters of tomato, especially in the Mediterranean region with a high range of salinity

Machine learning models for spatial prediction of groundwater potentiality in a large semi-arid mountainous region: application to the rherhaya watershed, High Atlas, Morocco

info:eu-repo/semantics/publishedVersio

Flood Susceptibility Assessment through Statistical Models and HEC-RAS Analysis for Sustainable Management in Essaouira Province, Morocco

Floods are natural disasters that often impact communities living in low-lying areas in the northern and central parts of Morocco. In this study, our aim was to create a flood susceptibility map using three methods; the hierarchy process (AHP) frequency ratio model (FR) and the weights of evidence (WoE) model. We extensively examined the area identified by these approaches using a hydraulic analysis software called HEC-RAS (version 6.3.1). Our analysis focused on the Essaouira watersheds in Morocco, where we identified around 197 flood locations. Out of these, we randomly selected 70% for modeling purposes while the remaining 30% were used for validation. Ten factors that influence floods were considered, such as slope, elevation, proximity to rivers, drainage density, stream order, land use patterns, rainfall data, lithology (permeability level) index (TWI), and curvature. We obtained these factors from data sources. Finally, we generated a flood susceptibility map and evaluated its accuracy by calculating the area under the curve (AUC). The validation results confirmed that all three models were robust and effective with an AUC of 90. Moreover, the research uncovered a trend of vulnerability with the most susceptible area being in close proximity to the city of Essaouira along the Oued Ksob. A detailed analysis using HEC-RAS was conducted at this identified location, pinpointing the village of Diabat as highly exposed. These findings hold significance for flood management, empowering decision makers, scholars, and urban planners to make informed choices and implement strategies that can minimize the impact of floods in susceptible regions while minimizing potential damages.info:eu-repo/semantics/publishedVersio

How to Intervene in the Caries Process: Dentin Caries in Primary Teeth

For an ORCA/EFCD consensus, this review systematically assessed available evidence regarding interventions performed and materials used to manage dentin carious lesions in primary teeth. A search for systematic reviews (SRs) and randomized clinical trials (RCTs) with a follow-up of at least 12 months after intervention was performed in PubMed, LILACS, BBO, and the Cochrane Library. The risk of bias tool from the Cochrane Collaboration and the PRISMA Statement were used for assessment of the included studies. From 101 screened articles, 2 SRs and 5 RCTs, which assessed the effectiveness of interventions in terms of pulp vitality and success of restoration, and 10 SRs and 1 RCT assessing the success of restorative materials were included. For treatments involving no carious tissue removal, the Hall technique showed lower treatment failure for approximal carious lesions compared to complete caries removal (CCR) and filling. For the treatment of deep carious lesions, techniques involving selective caries removal (SCR) showed a reduction in the incidence of pulp exposure. However, the benefit of SCR over CCR in terms of pulp symptoms or restoration success/failure was not confirmed. Regarding restorative materials, preformed metal crowns (PMCs) used to restore multisurface lesions showed the highest success rates compared to other restorative materials (amalgam, composite resin, glass ionomer cement, and compomer), and in the long term (12–48 months) these were also less likely to fail. There is limited evidence supporting the use of PMCs to restore carious lesions with single cavities. Among nonrestorative options, silver diammine fluoride was significantly more effective in arresting caries than other treatments for treating active carious lesions of different depths. Considerable heterogeneity and bias risk were observed in the included studies. Although heterogeneity observed among the studies was substantial, the trends were similar. In conclusion, less invasive caries approaches involving selective or no caries removal seem advantageous in comparison to CCR for patients presenting with vital, symptomless, carious dentin lesions in primary teeth. There is evidence in favor of PMCs for restoring multisurface carious lesions in primary molars

New macaque fossil remains from Morocco

Altres ajuts: CERCA Programme/Generalitat de Cataluny