A simple maximum power point tracking based control strategy applied to a variable speed squirrel cage induction generator

This paper presents a comprehensive modelling and control study of a variable speed wind energy conversion system based on a squirrel-cage induction generator (SCIG). The mathematical model of the SCIG is derived in Park frame along with the indirect field oriented control (IFOC) scheme based on a proportional and integral speed controller. A simple maximum power point tracking strategy is used to determine the optimal speed under variable wind speed conditions which is then used as the reference in the IFOC scheme. Power flow between the supply and the inverter is regulated via simultaneous control of the active and reactive currents of the grid and the DC link voltage. The simulation results show that the proposed control technique is able to maximise the energy extracted from the wind during the simulation scenarios considered. The results also demonstrate good transient response characteristics in the decoupled real and reactive powers.Peer reviewedFinal Accepted Versio

Control of the power quality for a DFIG powered by multilevel inverters

This paper treats the modeling, and the control of a wind power system based on a doubly fed induction generator DFIG, the stator is directly connected to the grid, while the rotor is powered by multilevel inverters. In order to get a decoupled system of controlfor an independently transits of active and reactive power, a vector control method based on stator flux orientation SFOC is considered: Direct vector control based on PI controllers. Cascaded H-bridge CHBI multilevel inverters are used in the rotor circuit to study its effect on supply power quality. All simulation models are built in MATLAB/Simulink software. Results and waveforms clearly show the effectiveness of vector control strategy. Finally, performances of the system will tested and compared for each levels of inverter

Don't forget primary progressive aphasia for anti-amyloid drugs: An estimation of eligible patients from the Lausanne Memory Center registry.

The study recently published on the clinical effect of lecanemab in early Alzheimer's disease (AD) only includes patients with amnestic presentation. However, a significant portion of AD patients presents a non-amnestic phenotype of AD, such as primary progressive aphasia (PPA) and could benefit of rather than on lecanemab. Therefore, we conducted a 10-year retrospective study at the Leenaards Memory Center in Lausanne (Switzerland) to identify how many PPA patients would be eligible for lecanemab. Among 54 patients with PPA, we identified 11 (20%) eligible patients. Furthermore, almost half of the 18 patients with logopenic variant would be eligible for lecanemab treatment

Application of Recurrent Neural Networks for Drought Projections in California

We use recurrent neural networks (RNNs) to investigate the complex interactions between the long-term trend in dryness and a projected, short but intense, period of wetness due to the 2015-2016 El Niño. Although it was forecasted that this El Niño season would bring significant rainfall to the region, our long-term projections of the Palmer Z Index (PZI) showed a continuing drought trend, contrasting with the 1998-1999 El Niño event. RNN training considered PZI data during 1896-2006 that was validated against the 2006-2015 period to evaluate the potential of extreme precipitation forecast. We achieved a statistically significant correlation of 0.610 between forecasted and observed PZI on the validation set for a lead time of 1 month. This gives strong confidence to the forecasted precipitation indicator. The 2015-2016 El Niño season proved to be relatively weak as compared with the 1997-1998, with a peak PZI anomaly of 0.242 standard deviations below historical averages, continuing drought conditions

Spatio-temporal evolution of the physico-chemical parameters of the Inaouen wadi and its tributaries

In order to assess the water quality of the Inaouen Wadi and its main tributaries, a monitoring of the physico-chemical parameters of twelve stations has been carried out during an entire annual cycle (year 2019). We measured ten parameters (T°, pH, electrical conductivity, total hardness, sulphates, ortho-phosphates, dissolved oxygen and nitrogen compounds) and five heavy metals were determined (iron, zinc, copper, lead, silver). The upstream stations (S1, S3, S4, S5 and S6) are the most polluted. These stations have the highest sulphate, ortho-phosphate, biological oxygen demand and nitrogen compounds. This pollution is a consequence of the solid and liquid wild discharges brought by the S1 and S5 tributaries and the urban agglomerations installed on the Inaouen river banks, which have a direct and important impact on the quality of water in the whole wadi. In addition, heavy metals (Zn, Iron, Ag and Cu) present high levels upstream of the Inaouen while passing downstream. A statistical multi-variate study using PCA (Principal Component Analysis) revealed that the content of these parameters remains low downstream of this river (S11) and the tributaries S10, S9 and S7 compared to upstream (S5). This pollution generated upstream is mainly caused by human actions (wastewater discharges, agricultural and industrial activities) without prior treatment. The main factors that reduce the pollution load downstream of the Inaouen wadi are self-purification and the tributaries leaving the Middle Atlas characterized by good water quality

Studies on Cu and TiO[2] Water-based Nanofluids: A Comparative Approach in Laminar Flow

In this paper, a numerical simulation has been performed to study the fluid fllow and heat transfer around a circular cylinder utilizing Cu and TiO2 water-based nanofluids over low Reynolds numbers. Here, the Reynolds number is varied within the range of 1 to 40 and the volume fraction of nanoparticles (ᵩ) is varied within the range of 0 < ᵩ < 0.05. Two-dimensional and steady mass continuity, momentum, and energy equations have been discretized using finite volume method. SIMPLE algorithm has been applied for solving the pressure linked equations. The effect of volume fraction of nanoparticles on fluid flow and heat transfer were investigated numerically. It was found that at a given Reynolds number, the Nusselt number, drag coefficient, re-circulation length, and pressure coefficient increases by increasing the volume fraction of nanoparticles

The 6th international conference on envenomation by snakebites and scorpion stings in Africa : a crucial step for the management of envenomation

During the 6th International Conference on Envenomation by Snakebites and Scorpion Stings in Africa held in Abidjan, from 1 to 5 June 2015, the measures for the management of envenomation were discussed and new recommendations were adopted by the participants. The high incidence and severity of this affliction were confirmed by several studies conducted in African countries. The poor availability of antivenom, particularly because of the cost, was also highlighted. Some experiences have been reported, mainly those regarding the financial support of antivenom in Burkina Faso (more than 90 %) and Togo (up to 60 %) or the mandatory reporting of cases in Cameroon. Key recommendations concerned: improvement of epidemiological information based on case collection; training of health workers in the management of envenomation; policy to promote the use of effective and safe antivenom; and antivenom funding by sharing its costs with stakeholders in order to improve antivenom accessibility for low-income patients

CONTRIBUTION AU DESIGN, STABILITÉ, PERFORMANCE ET OPTIMISATION D’UN UAV

Ce travail porte sur la simulation numérique, l’étude de performance, la stabilité et l’optimisation d’un modèle de drone (PIPER CUB J3).Dans ce but plusieurs logiciels de conception et de dessin assisté par ordinateur ont été utilisés : le modèle de l’UAV est conçu sous le logiciel « SolidWorks », les étapes de maillage et résolution des équations de Navier-Stokes décrivant l’écoulement sous « Ansys 16.0 », l’étude de stabilité et performance de vol par « Advanced Anlysis Aircraft 2.5 ».Pour des fins d’optimisation et d’amélioration en termes de finesse et d’endurance, trois types d’ailette ont été étudié