OALib Journal期刊

ISSN: 2333-9721



匹配条件: “Mahjoub Dridi” ,找到相关结果约183条。
Combinatorial optimization algorithms for intelligent vehicle sequencing problem at an isolated intersection
Fei Yan,Mahjoub Dridi,Abdellah EL Moudni
International Journal of Combinatorial Optimization Problems and Informatics , 2012,
Abstract: With the development of telecommunication and miniaturization technology, advantages brought by intelligent vehicles are more and more studied for designing new traffic control systems. In this paper, we present a novel vehicle sequencing strategy at an isolated intersection based on the information received from approaching intelligent vehicles. A Branch and Bound algorithm and an efficient heuristic are proposed to find an optimal or approximate vehicle passing sequence. The objective is to improve the congestion by minimizing the overall vehicle evacuation time. Structural properties are carefully analyzed to simplify the search procedure. Computational experiments and simulations are also carried out to evaluate the performance of the proposed algorithms.
Tracking Individual Targets in High Density Crowd Scenes Analysis of a Video Recording in Hajj 2009  [PDF]
Mohamed H. Dridi
Current Urban Studies (CUS) , 2015, DOI: 10.4236/cus.2015.31005
Abstract: In this paper we present a number of methods (manual, semi-automatic and automatic) for tracking individual targets in high density crowd scenes where thousands of people are gathered. The necessary data about the motion of individuals and a lot of other physical information can be extracted from consecutive image sequences in different ways, including optical flow and block motion estimation. One of the famous methods for tracking moving objects is the block matching method. This way to estimate subject motion requires the specification of a comparison window which determines the scale of the estimate. In this work we present a real-time method for pedestrian recognition and tracking in sequences of high resolution images obtained by a stationary (high definition) camera located in different places on the Haram mosque in Mecca. The objective is to estimate pedestrian velocities as a function of the local density. The resulting data of tracking moving pedestrians based on video sequences are presented in the following section. Through the evaluated system the spatiotemporal coordinates of each pedestrian during the Tawaf ritual are established. The pilgrim velocities as function of the local densities in the Mataf area (Haram Mosque Mecca) are illustrated and very precisely documented. Tracking in such places where pedestrian density reaches 7 to 8 persons/m2 is extremely challenging due to the small number of pixels on the target, appearance ambiguity resulting from the dense packing, and severe inter-object occlusions. The tracking method which is outlined in this paper overcomes these challenges by using a virtual camera which is matched in position, rotation and focal length to the original camera in such a way that the features of the 3D-model match the feature position of the filmed mosque. In this model an individual feature has to be identified by eye, where contrast is a criterion. We do know that the pilgrims walk on a plane, and after matching the camera we also have the height of the plane in 3D-space from our 3D-model. A point object is placed at the position of a selected pedestrian. During the animation we set multiple animation-keys (approximately every 25 to 50 frames which equals 1 to 2 seconds) for the position, such that the position of the point and the pedestrian overlay nearly at every time. By combining all these variables with the available appearance information, we are able to track individual targets in high density crowds.
Pedestrian Flow Simulation Validation and Verification Techniques  [PDF]
Mohamed H. Dridi
Current Urban Studies (CUS) , 2015, DOI: 10.4236/cus.2015.32011
Abstract: For the verification and validation of microscopic simulation models of pedestrian flow, we have performed experiments for different kind of facilities and sites where most conflicts and congestion happens e.g. corridors, narrow passages, and crosswalks. The validity of the model should compare the experimental conditions and simulation results with video recording carried out in the same condition like in real life e.g. pedestrian flux and density distributions. The strategy in this technique is to achieve a certain amount of accuracy required in the simulation model. This method is good at detecting the critical points in the pedestrians walking areas. For the calibration of suitable models we use the results obtained from analysing the video recordings in Hajj 2009 and these results can be used to check the design sections of pedestrian facilities and exits. As practical examples, we present the simulation of pilgrim streams on the Jamarat bridge (see Figure 5). The objectives of this study are twofold: first, to show through verification and validation that simulation tools can be used to reproduce realistic scenarios, and second, gather data for accurate predictions for designers and decision makers.
Simulation of High Density Pedestrian Flow: A Microscopic Model  [PDF]
Mohamed H. Dridi
Open Journal of Modelling and Simulation (OJMSi) , 2015, DOI: 10.4236/ojmsi.2015.33009
Abstract: In recent years, modelling crowd and evacuation dynamics has become very important, with increasing huge numbers of people gathering around the world for many reasons and events. The fact that our global population grows dramatically every year and the current public transport systems are able to transport large amounts of people heightens the risk of crowd panic or crush. Pedestrian models are based on macroscopic or microscopic behaviour. In this paper, we are interested in developing models that can be used for evacuation control strategies. This model will be based on microscopic pedestrian simulation models, and its evolution and design requires a lot of information and data. The people stream will be simulated, based on mathematical models derived from empirical data about pedestrian flows. This model is developed from image data bases, so called empirical data, taken from a video camera or data obtained using human detectors. We consider the individuals as autonomous particles interacting through social and physical forces, which is an approach that has been used to simulate crowd behaviour. The target of this work is to describe a comprehensive approach to model a huge number of pedestrians and to simulate high density crowd behaviour in overcrowding places, e.g. sport, concert and pilgrimage places, and to assist engineering in the resolution of complicated problems through integrating a number of models from different research domains.
Alu Mobile Elements: From Junk DNA to Genomic Gems
Sami Dridi
Scientifica , 2012, DOI: 10.6064/2012/545328
Entre foi et compromis tribal :
Dridi Moez
Chroniques Yéménites , 2007,
Abstract: On comprend mieux l’adhésion d’Oman à l’islam, entre 628 et 633 si on l’étudie dans son contexte historique et en relation avec les enjeux politiques et économiques de l’époque. Depuis le ive siècle de l’ère chrétienne, la c te orientale de la péninsule arabique se trouvait dans l’aire d’influence de l’empire sassanide, et la région d’Oman, Mazun, était administrée par un gouverneur perse, marzuban, contr lant un roi arabe local. Centré sur les ports de Daba et Suhar (Suhar), cette entité politique bénéficiait des revenus du commerce international avec l’Asie occidentale. Les premiers contacts épistolaires du Prophète Muhammad avec les chefs de tribus et rois locaux furent suivis par une série d’accords de reconnaissance de sa tutelle spirituelle nominale, sans que l’on puisse encore parler d’ islamisation . C’est seulement à la mort du Prophète, que la révolte de la ridda ( apostasie ) provoqua, avec une intervention militaire directe de l’état mecquois, le départ des Perses et l’entrée véritable d’Oman dans l’islam. Between Faith and Tribal Compromise: How the Region of Oman entered IslamThe adhesion of Oman to Islam between 628 and 633 is better understood when it is studied in its historical context along with its relation to the major political and economic events of the period. Starting from the 4th c. of the Christian era, the Eastern coast of the Arabic peninsula was under the influence of the Sassanid Empire, the region of Oman, Mazun, being administrated by the Persian government, marzuban, which controlled a local Arab king . This political entity, centered on the ports of Daba and Suhar, was deriving benefit from the revenue from international trade with West Asia. The first epistolary contacts of the prophet Muhammad with the local tribal leaders and kings were followed by a series of agreements recognizing his nominal spiritual guardianship. However, at this stage, one cannot talk about islamisation yet. Only after the death of the Prophet and the wars of ridda (apostasy), which provoked a direct military intervention of the Meccan State, and thus causing the Persians to depart can we say that Oman entered Islam.
Alu Mobile Elements: From Junk DNA to Genomic Gems
Sami Dridi
Scientifica , 2012, DOI: 10.6064/2012/545328
Abstract: Alus, the short interspersed repeated sequences (SINEs), are retrotransposons that litter the human genomes and have long been considered junk DNA. However, recent findings that these mobile elements are transcribed, both as distinct RNA polymerase III transcripts and as a part of RNA polymerase II transcripts, suggest biological functions and refute the notion that Alus are biologically unimportant. Indeed, Alu RNAs have been shown to control mRNA processing at several levels, to have complex regulatory functions such as transcriptional repression and modulating alternative splicing and to cause a host of human genetic diseases. Alu RNAs embedded in Pol II transcripts can promote evolution and proteome diversity, which further indicates that these mobile retroelements are in fact genomic gems rather than genomic junks. 1. Introduction Alu repeat elements are the most abundant interspersed repeats in the human genome. They are a family of short interspersed nuclear elements (SINEs) that use the reverse transcriptase and nuclease encoded by long interspersed nuclear elements (LINEs) to integrate into the host genome [1–3] and are found in the human genome in a number of ~1.100,000 copies, covering ~10% of its total length [4]. Functioning as transacting regulators of gene expression, pol III transcribed Alu and B1/2 (Alu-like elements in mouse) RNAs can interact with pol II and repress mRNA transcription [5–7]. Inverted Alu repeats are target for A-to-I editing by adenosine deaminases (ADARs) and can cause alternative splicing and drive proteome diversity [8]. Beside its role in human genomic evolution and diversity, Alu insertions and Alu-mediated unequal recombination contribute to a significant proportion of human genetic diseases [9]. Alu RNAs can also induce age-related macular degeneration following direct cytotoxicity to retinal pigment epithelium (RPE) cells [10]. In this brief paper, the author will describe the structure of human (Alu) and murine (B1, B2, ID, and B4) retroelements, a broad overview of the contribution of Alu retrotransposition to human diseases, and finally describe in depth a novel role of double-stranded Alu RNAs affecting the progression of age-related macular degeneration (AMD) and Alu editing by ADARs. 2. Structure of Alu and Murine Mobile Elements Alu typical sequences are ~300 nucleotides long and are classified into subfamilies according to their relative ages (for review see [11]). They have a dimeric structure and are composed of two similar but distinct monomers: left and right arms of 100 and 200 nucleotides long,
On the geometry of the first and second Painlevé equations
Raouf Dridi
Mathematics , 2007,
Abstract: In this paper we \emph{explicitly} compute the transformation that maps the generic second order differential equation $y''= f(x, y, y')$ to the Painlev\'e first equation $y''=6y^2+x$ (resp. the Painlev\'e second equation ${y''=2 y^{3}+yx+ \alpha}$). This change of coordinates, which is function of $f$ and its partial derivatives, does not exist for every $f$; it is necessary that the function $f$ satisfies certain conditions that define the equivalence class of the considered Painlev\'e equation. In this work we won't consider these conditions and the existence issue is solved \emph{on line} as follows: If the input equation is known then it suffices to specialize the change of coordinates on this equation and test by simple substitution if the equivalence holds. The other innovation of this work lies in the exploitation of discrete symmetries for solving the equivalence problem.
All-Optical Fiber Interferometer-Based Methods for Ultra-Wideband Signal Generation
Kais Dridi,Habib Hamam
Journal of Electrical and Computer Engineering , 2012, DOI: 10.1155/2012/314872
Abstract: We report two new, simple, and cost-effective all-optical methods to generate ultra-wideband (UWB) impulse radio signals. The proposed methods are based on fiber-interferometric structures, where an input pulse is split and propagates along the two interferometer arms. The interference of these pulses at the output of the interferometer leads to UWB pulse generation. A theoretical analysis is provided and some relevant simulation results are presented. Large bandwidths are obtained while satisfying the requirements of the Federal Communication Commission (FCC). With these two techniques, UWB pulses can be readily generated and cost-effectively propagated through optical fibers.
Effet de l'acide indole butyrique, de l'acide gibbérellique et d'un inhibiteur d'éthylène sur la fructification et la qualité des fruits du piment cultivé sous serre froide
Tarchoun, N.,Dridi, B.
Tropicultura , 2005,
Abstract: Effect of Indole Butyric Acid, Gibberellic Acid and an Ethylene Inhibitor on Fructification and Fruit Quality of Pepper Grown under Unheated Plastic House. The yield and fruit quality of pepper grown under unheated plastic house are usually negatively affected by low night temperature occurring during four to five months, this disrupt the local market supply and restrict the export possibilities. The effect of indole butyric acid (AIB), gibberellic acid (GA3) and an ethylene inhibitor (AgNO3) on fructification and fruit quality of two hot and two sweet pepper varieties grown under unheated plastic house, was studied. These substances, sprayed once per week just before flower initiation of the first four bifurcations, stimulated flower initiation and development; AgNO3 produced a significant increase in flower buds (98% more than the control) and reduced the buds abortion. Treatments did not affect bud flower and flower abortion, but increased fruit characteristics; treatment with AIB produced the longest fruits and the highest number of seed per fruit. On Beldi, hot pepper variety, gibberellic acid and indole butyric acid treatment increased fruit soluble solid content, citric acid, ascorbic acid concentration and chlorophyll a content, while AgNO3 treatment increased chlorophyll b concentration.

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