Preliminary evaluation of the status of olive-infecting viruses in Morocco

Olive is one of the most ancient and important fruit tree crops in Morocco. Olive trees are affected by at least 15 viruses belonging to eight genera. Most of these viruses were isolated from symptomless trees and/or reported in a very limited number of trees. In order to check for the presence of olive-infecting viruses in Morocco, a preliminary survey was conducted during March-April 2014 and a total of 105 samples (cv. Picholine marocaine) were randomly collected from 15 commercial orchards located in three important olive-growing regions: Béni Mellal, Marrakech and Meknès. Samples were tested by RT-PCR, using specific primers, to search for the presence of eight olive viruses: Olive latent virus 1 (OLV-1), Olive latent virus 2 (OLV-2), Strawberry latent ringspot virus (SLRSV), Cucumber mosaic virus (CMV), Arabis mosaic virus (ArMV), Cherry leaf roll virus (CLRV), Olive latent ringspot virus (OLRSV) and Olive leaf yellowing-associated virus (OLYaV). About one third (34.3%) of the trees were infected. In particular, the closterovirus OLYaV was the most widespread, as it was detected in 16.2% of the samples, followed by the necrovirus OLV-1 (8.6%), the oleavirus OLV-2 (3.8%), the cucumovirus CMV (2.8%), the sadwavirus SLRV (1.9%), and the nepovirus ArMV (0.9%). The fact that these infections are mostly latent and the increasing of national demand for propagation material of high sanitary standard call for the implementation of a cleanup using both heat therapy and in vitro propagation for the establishment of olive foundation blocks. Key-words: Olive trees, olive-infecting viruses, Morocc

Educating Students Through Understanding the Pathology of Geotechnical Projects

Three projects of end of studies which are related to soil mechanics pathology case histories were undertaken by students at civil engineering department of National Engineering School of Tunis. The two first projects dealt with Joumine and Sidi Saâd earth dams cases. For Joumine dam, concrete slabs of the spillway have been affected by serious disorders. The first disorder is related to the swelling nature of soil foundation of concrete slabs. The second disorder is attributed to high excess pore pressure responsible of slabs up risings. As solution the jet grouting technique was designed to eliminate high pore pressure in the soil foundation of slabs. For Sidi Saâd dam disorders were attributed to high active soil pressures exerted on retaining walls of the spillway. As solution anchored cables were adopted to improve the stability of concrete walls. The third project dealt with four engineering structures crossing Tunis La Goulette express route. All approach slabs were affected by differential settlements due to the existence of highly compressible thick soft clay layers. As solution three soil improvement techniques (rigid inclusions, stone columns prefabricated vertical drains) were compared to stop non admissible consolidation settlements. For each case history, the methodology to diagnose causes of disorders is first presented, second, the utilized approaches, especially those involving finite element codes usage, are highlighted, finally proposal of remedies to re establish suitable exploitation of projects are exposed. This paper well illustrates the great importance for under graduated students, when preparing their works of end of projects, to more understand fundamentals in soil mechanics in parallel with treating serious problems of pathology of case histories

Energy distribution in formant bands for arabic vowels

The acoustic cues play a major role in speech segmentation phase; the extraction of these indexes facilitates the characterization of the speech signal. In this work, we aim to study Arabic vowels (/a/, /a:/, /i/, /i:/, /u/ and /u:/), especially the long ones. We are interested in characterizing this type of vowels in terms of time, frequency and energy. The cues extracted and analyzed in this work are: segment length, voicing degree and formants values

Electric Motor Drive Selection Issues for HEV Propulsion Systems: A Comparative Study

International audienceThis paper describes a comparative study allowing the selection of the most appropriate electric propulsion system for a parallel Hybrid Electric Vehicle (HEV). This study is based on an exhaustive review of the state of the art and on an effective comparison of the performances of the four main electric propulsion systems that are the dc motor, the induction motor, the permanent magnet synchronous motor, and the switched reluctance motor. The main conclusion drawn by the proposed comparative study is that it is the cage induction motor that better fulfils the major requirements of the HEV electric propulsion

Advanced Fault-Tolerant Control of Induction-Motor Drives for EV/HEV Traction Applications: From Conventional to Modern and Intelligent Control Techniques

International audienceThis paper describes active fault-tolerant control systems for a high-performance induction-motor drive that propels an electrical vehicle (EV) or a hybrid one (HEV). The proposed systems adaptively reorganize themselves in the event of sensor loss or sensor recovery to sustain the best control performance, given the complement of remaining sensors. Moreover, the developed systems take into account the controller-transition smoothness, in terms of speed and torque transients. The two proposed fault-tolerant control strategies have been simulated on a 4-kW induction-motor drive, and speed and torque responses have been carried to evaluate the consistency and the performance of the proposed approaches. Simulation results, in terms of speed and torque responses, show the global effectiveness of the proposed approaches, particularly the one based on modern and intelligent control techniques in terms of speed and torque smoothness

Linear time-varying flatness-based control of Anti-lock Brake System (ABS)

In this paper, a flatness-based control strategy for linear time-varying systems is proposed in order to track a desired trajectory. The flatness-based control is designed by using two observers: a reduced order observer with a constant estimator error gain and an exact observer for designing a polynomial two-degrees-of-freedom controller without resolving Bezout equation in time varying framework. The proposed approach is illustrated with the control of an Anti-lock Brake System (ABS) and led to track a given trajectory for the wheel slip

Numerical parametric study of a cooling system for an LNG storage tank

International audienceThe study of the cooling system of a Liquefied Natural Gas (LNG) storage tank is vital for the safety of the installation. The objective of this paper is to develop cooling baffles capable of reducing the heat gain from the environment leading to a loss of LNG quantity, keeping the Boil-Off Gas (BOG) under control. For this purpose, a specific code based on the finite volume method was developed to improve our knowledge of the hydrodynamic and thermal behaviors of LNG in the cylindrical tank. In addition, the effect of the number, position and dimension of the baffles on the flow structure of LNG were determined. The obtained results indicated that the location of the baffles at the top of the tank nearby the vicinity of the wall would yield a better cooling of the LNG. Moreover, we emphasized that a number of six baffles would give rise to a better heat transfer. For a design purpose, the Nusselt numbers on the lateral surface and on the baffles have been correlated as functions of Rayleigh and baffle numbers