New M5P model tree‐based control for doubly fed induction generator in wind energy conversion system

This paper presents a new algorithm based on the combination of fuzzy logic control with M5 decision tree algorithm for doubly fed induction generator active and reactive power control. The M5 model tree is a machine learning algorithm that uses the extracted dataset from fuzzy logic for the aim of control performance enhancement. Because the fuzzy logic provides high design and implementation complexity, the new control approach is proposed to reduce its complexity and to achieve fast dynamic control by translating the fuzzy logic algorithm into simple if‐then instructions using M5 model tree. The obtained model shows good agreement with fuzzy logic in rotor side control. The effectiveness of the proposed control approach is investigated through Matlab/Simulink software. Furthermore, a cosimulated through processor in the loop testing is performed as an experimental verification using a low‐cost STM32F407 discovery board.     

Chemical Composition and Antimicrobial and Antioxidant Activities of Mentha (longifolia L. and viridis) Essential Oils

ABSTRACT:  The study was aimed to investigate essential oil chemical composition (gas chromatography/flame ionization detection [GC-FID] and gas chromatography/mass spectrometry [GC-MS]) and antioxidant (1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate [ABTS] assays) and antimicrobial (Gram-positive and Gram-negative bacteria, fungi, and yeast) activities of essential oils extracted from leaves of  Mentha longifolia  L. and  Mentha viridis . GC-MS analysis revealed that  M. longifolia  was constituted by pulegone (54.41%) as a major component followed by isomenthone (12.02%), 1,8-cineole (7.41%), borneol (6.85%), and piperitenone oxide (3.19%).  M. viridis  was rich in carvone (50.47%), 1,8-cineole (9.14%), and limonene (4.87%). The antioxidant activity by ABTS assay showed  IC ₅₀ values of 476.3 ± 11.7 and 195.1 ± 4.2 mg/L for  M .  longifolia  and  M .  viridis , respectively, the DPPH assays have resulted in a moderate  IC ₅₀ (>8000 mg/L and 3476.3 ± 133 mg/L for  M .  longifolia  and  M .  viridis , respectively). Antimicrobial activity showed that  Listeria monocytogenes  and  Klebsiella pneumoniae  bacteria were more inhibited by the 2 essential oils tested.  Escherichia coli  was least susceptible. A strong activity was also observed on fungi and yeasts. Carvone, thymol, and piperitone oxide have not been detected in Tunisian  M. longifolia . Camphor is reported for the 1st time for  M. viridis . Antioxidant and antibacterial activities were correlated to chemical composition.     

Towards a better understanding of the release mechanisms of caffeine from PLGA microparticles

Poly(lactic-co-glycolic acid) (PLGA)-based microparticles can be successfully used to control the release rate of a drug and optimize the therapeutic efficacy of a medical treatment. However, the underlying drug release mechanisms can be complex and are often not fully understood. This renders system optimization cumbersome. In this study, differently sized caffeine-loaded PLGA microparticles were prepared and the swelling and drug release behaviors of single microparticles were monitored upon exposure to phosphate buffer pH 7.4. Ensembles of microparticles were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, gel permeation chromatography, and optical microscopy. The observed triphasic drug release patterns could be explained as follows. The initial burst release can be attributed to the dissolution of tiny drug crystals with direct surface access. The subsequent second drug release phase (with an about constant release rate) could be attributed to the release of drug crystals in regions, which undergo local swelling. The third release phase (again rapid, leading to complete drug exhaust) could be explained by substantial polymer swelling throughout the systems. Once a critical polymer molecular weight is reached, the PLGA chains are sufficiently hydrophilic, insufficiently entangled and the osmotic pressure created by water soluble degradation products attracts high amounts of water into the system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48710.     

Spatial variability of the characteristics of combined wet weather pollutant loads in Paris

An on-site observatory of urban pollutant loads in combined sewers has been created in Paris in order to investigate wet weather pollutant loads at different spatial scales. This observatory is composed of six urban catchments, covering areas from 41 to 2581ha. For a wide range of parameters including suspended solids (SS), volatile suspended solids (VSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), metals (Cd, Cu, Pb, Zn), aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (AHs and PAHs), this article serves to evaluate the potential scale effect on wet weather flow (WWF) quality. Although the extensive data set compiled herein has emphasized the high variability in WWF quality from one rain event to the next, no scale effect could be observed for a given rain event on pollutant concentrations, distributions between dissolved and particulate phases, pollutant contents and loads. Such results are of prime importance since they suggest (i) no spatial scale influence on WWF quality for the considered catchments and (ii) similar dominant sources and transfer processes at the various spatial scales.