Distribution and status of Posidonia oceanica meadows on the North-Western coast of Algeria

Posidonia oceanica is an endemic species of the Mediterranean Sea that in pristine coastal waters forms extensive meadows, which are, actually, exposed to natural and anthropogenic pressures, causing their regression throughout the basin. The aim of our study is to summarise and evaluate current knowledge about the characterisation of Posidonia oceanica along the Western Algerian coast, in order to provide new evidence about the distribution and health status this species. To realize our objectives, we combined extracted data from published articles, theses, results of project reports, in situ observations and laboratory analysis. The results show the presence of the meadows in fifteen coastal zones of Western Algeria, mainly located in shallow surface waters from 0.5 to 18 metres depth.The mean leaf length across all sites ranged from 153 to 667 mm. The mean number of leaves/shoot ranged between 4.7 ± 0.9 and 6.0 ± 0.5 leaves/shoot. Leaf length showed a highly significant difference between the cold and hot season. The data analysis shows that the leaf biometric values and the shoot densities of the P. oceanica are greater than those of Mediterranean samples although these measures tend to decrease deeply. The analyses carried out on structural features of P. oceanica show that the Western Algerian meadows are, globally, in good health status according to standardised scale. The available data on P. oceanica summarised in this article represent an important starting point to build effective plans for understanding levels of environmental threats and for supporting conservation strategies for these important ecosystems. Conversely, the limited information available on this seagrass along the Western Algerian costs only allows the description of some structural features, and permits us to draw overall conclusions on its general health status

Comparative study between pi and fuzzy pi controllers for DFIG integrated in variable speed wind turbine

This paper presents the contribution of the application of fuzzy logic for the independent control of  the active and reactive power stator of a doubly fed induction generator (DFIG), used in a variable speed wind energy conversion system. So in this work, we are particularly interested in the application of indirect vector control by stator flux orientation to the DFIG, based on fuzzy controllers. These latter surpass the limits of conventional controllers and possess essential characteristics for the improvement of the robustness of the vector control with against parameters variations of the system. The obtained simulation results have shown that it is possible to control the stator powers, even in the presence of parametric variations

Design and experimental implementation of voltage control scheme using the coefficient diagram method based PID controller for two-level boost converter with photovoltaic system

Introduction. Currently, in the solar energy systems and a variety of electrical applications, the power converters are essential part. The main challenge for similar systems is controller design. In the literature, the PID controller has proved its effectiveness in many industrial applications, but determining its parameters remains one of the challenges in control theory field. The novelty of the work resides in the design and experimental implementation of a two-level boost DC-DC converter controlled by a PID controller for photovoltaic (PV) maximum power extraction. Purpose. Analysis and control of the two-level boost topology with renewable energy source and design of the PID controller parameters using simple and accurate method. Methods. PID coefficients are optimized using Coefficient Diagram Method (CDM) in the MATLAB environment. Results. A mathematical model of a two-level boost converter with PID controller and PV energy source was developed and analyzed. The model allows to design the controller parameters of the proposed system. Practical value. A prototype steered by the proposed CDM-PID controller was tested using an Arduino embedded board. A comparison between the simulation results and the experimental one is presented. The obtained results illustrate that the experimental results match the simulation closely, and the proposed CDM-PID controller provides a fast and precise results.Вступ. В даний час перетворювачі потужності є невід’ємною частиною сонячних енергетичних систем та різних електричних пристроїв. Основною проблемою для таких систем є проектування контролера. У літературі ПІД-регулятор довів свою ефективність у багатьох промислових застосуваннях, але визначення його параметрів залишається однією з проблем у галузі теорії управління. Новизна роботи полягає у розробці та експериментальній реалізації дворівневого підвищувального перетворювача постійного струму, керованого ПІД-регулятором, для отримання максимальної потужності фотоелектричних пристроїв. Мета. Аналіз та управління дворівневою топологією підвищення з використанням відновлюваного джерела енергії та розрахунок параметрів ПІД-регулятора простим та точним методом. Методи. Коефіцієнти ПІД оптимізуються за допомогою методу діаграми коефіцієнтів (CDM) у середовищі MATLAB. Отримані результати. Розроблено та проаналізовано математичну модель дворівневого підвищувального перетворювача з ПІД-регулятором та фотоелектричним джерелом енергії. Модель дозволяє спроєктувати параметри контролера пропонованої системи. Практична цінність. Прототип, керований пропонованим контролером CDM-PID, протестували з використанням вбудованої плати Arduino. Наведено порівняння результатів моделювання з експериментальними даними. Отримані результати показують, що експериментальні результати близько відповідають моделюванню, а пропонований CDM-ПІД-регулятор забезпечує швидкі та точні результати

Additional new records of Caulerpa cylindracea Sonder 1845 along the West Algerian Coasts

Since considered as invasive species, Caulerpa cylindracea Sonder 1845 has been the subject of numerous prospecting works aiming its localisation and identification along the western Mediterranean Coasts. In this study, we provide new occurrence of the introduced seaweed Caulerpa cylindracea in the West Algerian coasts. C. cylindracea has been reported for the first time in Canastel and Zimba (West Algerian coasts) at different density distribution levels. The colonisation level was estimated to Level (I) for Zimba, Canastel and Marsat El Hadjaj sites, which indicated a beginning of spreading. By contrast, in Cap Carbon a Level (II) was recorded suggesting an advanced colonisation of the invasive taxon. Macroalgae and seagrass assemblage characterisation showed low cover for all species in the invasion zone. Accordingly, Caulerpa cylindracea is more present in Cap Carbon than in Zimba, Canastel and Marsat El Hadjaj. Considering the observed abundance of macroalgae and seagrasses, Caulerpa prolifera seemed to resist the invasion of C. cylindracea in Marsat El Hadjaj

Additional new records of Caulerpa cylindracea Sonder 1845 along the West Algerian Coasts

122-129Since considered as invasive species, Caulerpa cylindracea Sonder 1845 has been the subject of numerous prospecting works aiming its localisation and identification along the western Mediterranean Coasts. In this study, we provide new occurrence of the introduced seaweed Caulerpa cylindracea in the West Algerian coasts. C. cylindracea has been reported for the first time in Canastel and Zimba (West Algerian coasts) at different density distribution levels. The colonisation level was estimated to Level (I) for Zimba, Canastel and Marsat El Hadjaj sites, which indicated a beginning of spreading. By contrast, in Cap Carbon a Level (II) was recorded suggesting an advanced colonisation of the invasive taxon. Macroalgae and seagrass assemblage characterisation showed low cover for all species in the invasion zone. Accordingly, Caulerpa cylindracea is more present in Cap Carbon than in Zimba, Canastel and Marsat El Hadjaj. Considering the observed abundance of macroalgae and seagrasses, Caulerpa prolifera seemed to resist the invasion of C. cylindracea in Marsat El Hadjaj

Sensorless Speed Control of Double Star Induction Machine With Five Level DTC Exploiting Neural Network and Extended Kalman Filter

This article presents a sensorless five level DTC control based on neural networks using Extended Kalman Filter (EKF) applied to Double Star Induction Machine (DSIM). The application of the DTC control brings a very interesting solution to the problems of robustness and dynamics. However, this control has some drawbacks such as the uncontrolled of the switching frequency and the strong ripple torque. To improve the performance of the system to be controlled, robust techniques have been applied, namely artificial neural networks. In order to reduce the number of sensors used, and thus the cost of installation, Extended Kalman filter is used to estimate the rotor speed. By viewing the simulation results using the MATLAB language for the control. The results of simulations obtained showed a very satisfactory behaviour of the machine

Double star induction motor direct torque control with fuzzy sliding mode speed controller

In this paper, we present a speed fuzzy sliding mode control for a direct torque controlled double star induction motor (DSIM). Direct torque control (DTC) uses only a couple of hysteresis comparators to perform both torque and flux dynamic control. The proposed control scheme utilizes a fuzzy sliding mode controller (FSMC) for the speed control. The FSMC is formed with the robustness of sliding mode control (SMC) and the smoothness of fuzzy logic (FL). Few fuzzy rules are used for this strategy control. The sliding mode control is used to achieve robust performance against parameter variations and external disturbances. The problem with this conventional controller is that it has large chattering on the torque and the drive is very noisy. In order to reduce chattering, the sign function is substituted with a fuzzy control law which draws the system state variables into prespecified bounds of sliding mode surface. The computer simulations are conducted to demonstrate the satisfactory tracking performance and robustness of the control with reduced chattering problem