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Search Results: 1 - 10 of 8832 matches for " Mohamed Bouri "
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Portfolio selection between rational and behavioral theories emergent markets case
Ezzeddine Ben Mohamed,Bouri Abdelfatteh
Management Science Letters , 2012,
Abstract: The aim of this paper is to explore the determinants of Portfolio Choice under the investors, professionals and academics’ perception. We introduce an approach based on cognitive mapping technique with a series of semi-directive interviews. Among a sample of 30 Tunisian individuals, we propose tow different frameworks: a mean-variance framework and a behavioral framework. Each framework is oriented to capture the effect of some concepts as proposed by the mean-variance portfolio theory and the behavioral portfolio theory on the portfolio choice decision. The originality of this research paper is guaranteed since it traits the behavioral portfolio choice in emergent markets. In the best of our knowledge this is the first study in the Tunisian context that explores such area of research. Ours results show that the Tunisian investors behave as it prescribed by the behavioral portfolio theory. They use some concepts proposed by the rational mean-variance theory of portfolio choice but they are affected by their emotions and some others cognitive bias when constructing and managing they portfolio of assets.
Collision Avoidance in Next-generation Fiber Positioner Robotic System for Large Survey Spectrograph
Laleh Makarem,Jean-Paul Kneib,Denis Gillet,Hannes Bleuler,Mohamed Bouri,Laurent Jenni,Francisco Prada,Justo Sanchez
Physics , 2013, DOI: 10.1051/0004-6361/201323202
Abstract: Some of the next generation massive spectroscopic survey projects, such as DESI and PFS, plan to use thousands of fiber positioner robots packed at a focal plane to quickly move in parallel the fiber-ends from the previous to the next target points. The most direct trajectories are prone to collision that could damage the robots and impact the survey operation. We thus present here a motion planning method based on a novel decentralized navigation function for collision-free coordination of fiber positioners. The navigation function takes into account the configuration of positioners as well as the actuator constraints. We provide details for the proof of convergence and collision avoidance. Decentralization results in linear complexity for the motion planning as well as dependency of motion duration with respect to the number of positioners. Therefore the coordination method is scalable for large-scale spectrograph robots. The short in-motion duration of positioner robots (~2.5 seconds using typical actuator constraints), will thus allow the time dedicated for observation to be maximized.
Efficiency concept and investigations in insurance industry: A survey
Bilel Jarraya,Abdelfatteh Bouri
Management Science Letters , 2013,
Abstract: Most recent studies are based on benchmarking analysis allowing the measure of company efficiency relatively to a reference performance. Benchmarking is a helpful tool to analyze and promote efficiency in insurance companies. The fast development of X-efficiency notion makes traditional performance measures (ROA, ROE, etc.) obsolete. Indeed, various methods have been used, various input-output measures have been proposed and various research fields have been explored in insurance company investigation. So, after reviewing most known efficiency concepts and their definitions, this section explores the literature review of two principal points of discussion: the first point is focused on the different used techniques to measure efficiency, including the developed approaches to define inputs, outputs and their prices. The second point represents an overview of efficiency investigations in insurance industry.
Collision-free motion planning for fiber positioner robots: discretization of velocity profiles
Laleh Makarem,Jean-Paul Kneib,Denis Gillet,Hannes Bleuler,Mohamed Bouri,Philipp H?rler,Laurent Jenni,Francisco Prada,Justo Sanchez
Physics , 2014, DOI: 10.1117/12.2055185
Abstract: The next generation of large-scale spectroscopic survey experiments such as DESI, will use thousands of fiber positioner robots packed on a focal plate. In order to maximize the observing time with this robotic system we need to move in parallel the fiber-ends of all positioners from the previous to the next target coordinates. Direct trajectories are not feasible due to collision risks that could undeniably damage the robots and impact the survey operation and performance. We have previously developed a motion planning method based on a novel decentralized navigation function for collision-free coordination of fiber positioners. The navigation function takes into account the configuration of positioners as well as their envelope constraints. The motion planning scheme has linear complexity and short motion duration (~2.5 seconds with the maximum speed of 30 rpm for the positioner), which is independent of the number of positioners. These two key advantages of the decentralization designate the method as a promising solution for the collision-free motion-planning problem in the next-generation of fiber-fed spectrographs. In a framework where a centralized computer communicates with the positioner robots, communication overhead can be reduced significantly by using velocity profiles consisting of a few bits only. We present here the discretization of velocity profiles to ensure the feasibility of a real-time coordination for a large number of positioners. The modified motion planning method that generates piecewise linearized position profiles guarantees collision-free trajectories for all the robots. The velocity profiles fit few bits at the expense of higher computational costs.
Developing Micro DC-Brushless Motor Driver and Position Control for Fiber Positioners
Laurent Jenni,Philipp H?rler,Laleh Makarem,Jean-Paul Kneib,Denis Gillet,Hannes Bleuler,Mohamed Bouri,Francisco Prada,Guillermo De Rivera,Justo Sanchez
Physics , 2014, DOI: 10.1117/12.2055197
Abstract: In the large-scale, Dark Energy Spectroscopic Instrument (DESI), thousands of fiber positioners will be used. Those are robotic positioners, with two axis, and having the size of a pen. They are tightly packed on the focal plane of the telescope. Dedicated micro-robots have been developed and they use 4mm brushless DC motors. To simplify the implementation and reduce the space occupancy, each actuator will integrate its own electronic control board. This board will be used to communicate with the central trajectory generator, manage low level control tasks and motor current feeding. In this context, we present a solution for a highly compact electronic. This electronic is composed of two layers. The first is the power stage that can drive simultaneously two brushless motors. The second one consists of a fast microcontroller and deals with different control tasks: communication, acquisition of the hall sensor signals, commutation of the motors phases, and performing position and current regulation. A set of diagnostic functions are also implemented to detect failure in the motors or the sensors, and to sense abnormal load change that may be the result of two robots colliding.
Moatemri Ouarda,Abdelfatteh el Bouri,Olivero Bernard
International Journal of Economics and Financial Issues , 2013,
Abstract: This study presents four main contributions to the literature of behavior herding. Firstly, it extends the behavioral researches of herding of the investors on a developed market and mainly on a European market as a whole. Secondly, we are interested in examination of herding behavior at the level of sectors by using data at the levels of companies. Thirdly, this document estimates the implications of herding behavior in terms of returns, volatility and volume of transaction. Fourthly, the herding behavior is revealed as well during the period of the recent global financial crisis in 2007-2008 and of Asian crisis. Our results reveal a strong evidence of herding behavior sharply contributed to a bearish situation characterized by a strong volatility and a trading volume. The repercussion of herding during the period of the recent financial crisis is clearly revealed for the sectors of the finance and the technology.
Expérimentation de la culture de chanvre industriel à fibres au Maroc Experiment of industrial hemp crops in Morocco
Stambouli Hamid,El Bouri Aziz,Bouayoun Taoufiq,El Karni Naima
Annales de Toxicologie Analytique , 2011, DOI: 10.1051/ata/2011105
Abstract: Objectif : Dans la perspective de la légalisation de la culture de chanvre à fibres au Maroc, une expérimentation de cette culture a été réalisée entre le 19/04/2010 et le 10/08/2010 dans quatre régions différentes du pays, et a concerné les trois variétés Santhica 27, Epsilon 68 et Futura 75, toutes autorisées en Europe ([Δ-9-THC] < 0.2 %). Méthodes : Les essais ayant été conduits dans des régions de situations géographiques, conditions climatiques et caractéristiques pédologiques différentes des cultures européennes, il convenait alors de vérifier le comportement de ces plantes par le contr le des rendements agronomiques et de leur teneur en Δ-9-THC. Les protocoles d’échantillonnage, de séchage et d’évaluation du taux du Δ-9-THC au sein de ces cultures, ont d’abord été réalisés d’une part conformément à la procédure B de l’Arrêté du 24 février 2004 du Règlement CE N° 1177/2000, et ensuite selon une méthode simplifiée basée sur la détermination du rapport α = Δ-9-THC/CBD, d’autre part. Résultats : Les meilleurs rendements en matière sèche, densité et hauteurs des plantes sont obtenus avec la variété Futura 75 dans les quatre sites, suivie de Epsilon 68 et de Santhica 27. Le contr le des teneurs de ces cultures en Δ-9-THC a conduit à des taux moyens inférieurs à la limite autorisée puisqu’ils se situent entre 0,013 % et 0,027 % pour la variété Epsilon 68, entre 0,023 % et 0,035 % pour la variété Futura 75 et des taux quasiment nuls (non détectables par GCFID) pour la variété Santhica 27. L’analyse de cette dernière variété par GC/MS mode SIM et en LCMSMS a permis la mise en évidence de traces du Δ-9-THC. Par ailleurs, le rapport α évalué respectivement à 0,042 et 0,047 pour les deux variétés Epsilon 68 et Futura 75, est de même ordre de grandeur que les valeurs obtenues habituellement pour les cultures de chanvre à fibres et reste nettement inférieur à 0,2. Conclusion : Les résultats préliminaires obtenus par les deux procédures réglementaire et simplifiée concordent et ne révèlent aucun dépassement des valeurs limites pour les trois variétés testées bien que les conditions de culture ne soient pas rigoureusement les mêmes que celles adoptées en Europe. En outre, la photopériode qui caractérise ces régions du sud de la Méditerranée étant très favorable, elle s’est traduite par une maturité rapide des cultures qui au bout de deux mois et demi ont toutes atteint le stade de fin de floraison. Objectives: In anticipation of the legalization of hemp fiber cultivation in Morocco, an experiment of this crops was conducted between 19/04/2010 and 10/08/2010 in f
The Effects of Residual Blood of Carcasses on Poultry Technological Quality  [PDF]
Bourbab Mohamed, Idaomar Mohamed
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.310181
Abstract: The objective of this work is to show the effect of residual blood on the quality of chicken meat, work based on the hypothesis that increasing the concentration of residual blood would explain the observed quality degradation by several authors. Lots of chickens are killed with two different types of slaughter: Slaughter without stunning for a maximum flow of blood or bleeding perfect PS, shooting seals slight lead to keep almost all blood from the carcass or bleeding IS flawed. To prove the residual blood factors that are responsible for high pHu level and high values of (L* A* B*) in poultry, this study compares the pHu level and values of (L* A* B*) in poultry both perfectly and imperfectly bled. Samples from imperfectly bled carcasses show a high value average number of A* = 12.68 and B* = 16.85; and L* = 54.09 VS the average number of A* = 8.50 and B* = 14.43 and L* = 50.27. At 3℃ storage temperature, the average pHu of perfectly bled poultry was (5.7) which was significantly (P < 0.01) lower than the average pHu of imperfectly bled poultry (6.08). At 7℃ storage temperature, the average pHu of perfectly bled poultry was (6.07) which was significantly (P < 0.05) lower than the average pHu of imperfectly bled one (6.27). We found out the effect of season on the results of pHu measures, so we conducted aanalysis of pHu in summer and winter. Residual blood of the poultry is responsible for high values of (L* A* B*) and high values of pHu therefore the deterioration of the poultry Colour.
Monitoring of Temporal and Spatial Changes of Land Use and Land Cover in Metropolitan Regions through Remote Sensing and GIS  [PDF]
Mohamed Ali Mohamed
Natural Resources (NR) , 2017, DOI: 10.4236/nr.2017.85022
Abstract: The use of remote sensing techniques and subsequent analysis by means of geographical information system (GIS) offers an effective method for monitoring temporal and spatial changes of landscapes. This work studies the urbanization processes and associated threats to natural ecosystems and resources in the metropolitan areas of Berlin and Erlangen-Fürth-Nürnber?Schwabach (EFNS). To compute the land use/cover (LULC) of the study areas, a supervised classification of “maximum likelihood” using Landsat data for the years of 1972, 1985, 1998, 2003, and 2015 is used. Results show that the built-up area is the dominant land use in both regions throughout the study period. This land use has increased at the expense of green and open areas in EFNS and at the expense of agricultural land in Berlin. Likewise, 5% of forest in EFNS is replaced with urban infrastructure. However, the amount of forest in Berlin increased by 3%. While EFNS experienced relatively big changes in its water bodies from 1972 to 1985, changes in water bodies in Berlin were rather slight during the last 40 years. The overall accuracy of our remotely sensed LULC maps was between 88% and 94% in Berlin and between 85.87% and 87.4% for EFNS. The combination of remote sensing and GIS appears to be an indispensable tool for monitoring changes in LULC in urban areas and help improving LU planning to avoid environmental and ecological problems.
Analysis of Digital Elevation Model and LNDSAT Data Using Geographic Information System for Soil Mapping in Urban Areas  [PDF]
Mohamed Ali Mohamed
Natural Resources (NR) , 2017, DOI: 10.4236/nr.2017.812047
This study applies digital analysis methods of topographic data derived from digital elevation models (DEMs) and Landsat remotely sensed spectral data using GIS tools to evaluate the quality and limitations of the morphometric parameters (terrain attributes: TAs). This aims to check its suitability for digital soil mapping (DSM) and survey in urban areas at the target scale 1:50,000. This scale represents the standard scale level for compiling soil inventories within all German states. The study is conducted on an urban area of 112.68 km2 in the southwest part of the state of Berlin in Germany. These relief units are the basis for determining the soil mapping units at the scale of 1:50,000. The generated preliminary soil map was compared to soil maps made using traditional soil survey methods. For the mainly natural soils, the equivalence area is 94.91%, and for the anthropogenic soils, the equivalence area is 95.34%. The proposed methodology is adequate for preliminary mapping of soil units based on the digital derivation of TAs. Landsat scenes are spatially explicit, physical representations of environmental covariates on the land surface. The free DEM-ASTER in combination with Landsat OLI images is found to be the appropriate model to represent the terrain surface and derive the TAs for environmental modeling and fitting of derivation the relief units and their topography features. However, the 30 m spatial resolution and the fairly coarse spectral resolution of DEMs and Landsat images limit their utility for digital soil mapping at this scale in urban areas with little topographic variation.
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