检索结果-南通市图书馆

On stability behaviors of 5D M-theory black objects

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第5期76卷 94-101页

作者： Adil Belhaj abderrahim Bouhouch Departement de Physique Equipe des Sciences de la matiere et du rayonnementESMaR Faculte des SciencesUniversite Mohammed V de RabatRabatMorocco

Using N=2 supergravity formalism,we investigate certain behaviors of five-dimensional black objects from the compactification of M-theory on a Calabi-Yau *** manifold has been constructed as the intersection of two homogeneous polynomials of degrees(ω+2,1)and(2,1)in a product of two weighted projective spaces given by WP^(4)(ω,1,1,1,1)×P^(1).First,we determine the allowed electric charge regions of the BPS and non BPS black holes obtained by wrapping M2-branes on appropriate two cycles in such a proposed Calabi-Yau *** that,we calculate the entropy of these solutions which takes a maximal value corresponding to ω=1 defining the ordinary projective space P^(4).For generic values of ω,we show that the non BPS states are ***,we conduct a similar study of five-dimensional black *** the allowed magnetic charge regions of the BPS and non BPS black stringy solutions derived from M5-branes on dual divisors,we calculate the tension taking a minimal value for P^(4).By determining the recombination factor,we show that the non-BPS black string states are stable in the allowed regions in the magnetic charge space.

关键词： M-theory Calabi-Yau manifolds black holes black strings stability behaviors

Gender-Based Analysis of User Reactions to Facebook Posts

在线全文

学校读者我要写书评

暂无评论

Big Data Mining and Analytics 2024年第1期7卷 75-86页

作者： Yassine El Moudene Jaafar Idrais Rida El Abassi abderrahim Sabour Mathematical Engineering and Computer Science Laboratory Faculty of SciencesIbn Zohr UniversityAgadir 8706Morocco Department of Computer Science Mathematical−High School of Technology Ibn Zohr UniversityAgadir 8706Morocco

Online Social Networks(OSNs)are based on the sharing of different types of information and on various interactions(comments,reactions,and sharing).One of these important actions is the emotional reaction to the *** diversity of reaction types available on Facebook(namely FB)enables users to express their feelings,and its traceability creates and enriches the users’emotional identity in the virtual *** paper is based on the analysis of 119875012 FB reactions(Like,Love,Haha,Wow,Sad,Angry,Thankful,and Pride)made at multiple levels(publications,comments,and sub-comments)to study and classify the users’emotional behavior,visualize the distribution of different types of reactions,and analyze the gender impact on emotion *** of these can be achieved by addressing these research questions:who reacts the most?Which emotion is the most expressed?

关键词： profiling knowledge extraction data mining emotion mining social media data crawling Facebook reactions gender

Graphite Carbone Structure

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Crystal Structure Theory and Applications 2024年第1期12卷 1-10页

作者： Lahbib Abbas Lahcen Bih Khalid Yamni abderrahim Elyahyaouy Abdelmalik El Attaoui Zahra Ramzi Materials Membranes and Nanotechnology Laboratory Faculty of Science and Technology Moulay Ismail University Errachidia Morocco Engineering Sciences and Professions Laboratory National School of Arts and Crafts Moulay Ismail University Meknes Morocco Materials Membranes and Nanotechnology Laboratory Chemistry Department Faculty of Sciences Moulay Ismail Univer-sity Meknes Morocco Physics Department Faculty of Sciences Ibn Tofail University Kenitra Morocco Laboratory of Molecular Chemistry Materials and Environment (LCM2E) Multidisciplinary Faculty of Nador Mohamed 1st University Nador Morocco Laboratory of SCiMATOP Chemistry Department Faculty of Sciences Semlalia Cadi Ayyad University Marrakech Morocco

Carbon graphite is a crystalline form of carbon consisting of layers of hexagonal carbon atoms arranged in a two-dimensional “graphene” structure. Graphene layers are stacked on top of each other, forming a three-dimensional structure with a high degree of anisotropy. The carbon atoms within each layer are linked together by strong covalent bonds, creating a strong, stable lattice structure. However, the layers themselves are held together by weak van der Waals forces, enabling them to slide easily over each other. The properties of carbon graphite are highly dependent on the orientation and alignment of the graphene layers. When the layers are aligned parallel to each other, the material exhibits high strength and stiffness along the alignment direction, but is weaker and more flexible in other directions. Carbon graphite is used in a variety of applications where high strength, rigidity and electrical conductivity are required. Some common applications include electrical contacts, electric motor brushes, and as a structural material in aerospace and defense applications. The aim of our work is to describe the structure of graphite, its physical and chemical properties and its applications.

关键词： Graphite Graphene Hexagonal Structure Hardness Rigidity Electrical Con-ductivity

Determination of Latent Heats of Vaporization and Fusion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Chemical Engineering and Science 2024年第3期14卷 113-124页

作者： Lahbib Abbas Lahcen Bih Khalid Yamni abderrahim Elyahyaouy Abdelmalik El Attaoui Zahra Ramzi Chemistry Department Faculty of Science and Technology Moulay Ismail University Meknes Er-Rachidia Morocco Engineering Sciences and Professions Laboratory National School of Arts and Crafts Moulay Ismail University Meknes Meknes Morocco Materials Membranes and Nanotechnology Chemistry Department Faculty of Sciences Moulay Ismail University Meknes Zitoune Mekns Morocco Physics Department Faculty of Sciences Ibn Tofail University Kenitra Morocco Laboratory of Molecular Chemistry Materials and Environment (LCM2E) Multidisciplinary Faculty of Nador Mohamed 1st University Oujda Nador Morocco Laboratory of SCiMATOP Chemistry Department Faculty of Sciences Semlalia Cadi Ayyad University Marrakech Morocco

Water is the most abundant liquid on the surface of the earth. It is a liquid whose properties are quite surprising, both as a pure liquid and as a solvent. Water is a very cohesive liquid: its melting and vaporization temperatures are very high for a liquid that is neither ionic nor metallic, and whose molar mass is low. Thus, water remains liquid at atmospheric pressure up to 100C while similar molecules such as H2S, H2Se, H2Te for example would give a vaporization temperature close to 80C. This cohesion is in fact ensured by hydrogen bonds between water molecules. This type of bonds between neighboring molecules, hydrogen bonds, is quite often found in chemistry [1] [2]. Any change in the state of aggregation of a substance occurs with the absorption or release of a certain amount of latent heat of transformation. Latent heat of fusion, vaporization or sublimation is the ratio of the energy supplied as heat to the mass of the substance that is melted, vaporized or sublimated. As a result of the reversibility of the processes, the fusion heat is equal to the heat released in the reverse process: crystallization and solidification heat. And likewise the heat of vaporization is equal to the heat of condensation. This equality of heat is often used to determine experimentally either of these quantities. There are two main measurement methods: 1) Direct measurement using the calorimeter, 2) Indirect measure based on the use of the VantHoff relationship. The objective of this work is to measure the latent heat of water vaporization and verify the compatibility of the experimental values with the values given by the tables using the indirect method.

关键词： Latent Heat of Vaporization Latent Heat of Fusion Calorimetry Relationship of Vant’Hoff

Systematic Method for Constructing Lewis Representations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Inorganic Chemistry 2024年第1期14卷 1-18页

作者： Lahbib Abbas Lahcen Bih Khalid Yamni abderrahim Elyahyaouy Abdelmalik El Attaoui Zahra Ramzi Materials Membranes and Nanotechnology Faculty of Science and Technology Moulay Ismail University Meknes Er-Rachidia Morocco Engineering Sciences and Professions Laboratory National School of Arts and Crafts Moulay Ismail University Meknes Meknes Morocco Materials Membranes and Nanotechnology Chemistry Department Faculty of Sciences Moulay Ismail University Meknes Meknes Morocco Physics Department Faculty of Sciences Ibn Tofail University Kenitra Morocco Laboratory of Molecular Chemistry Materials and Environment (LCM2E) Multidisciplinary Faculty of Nador Mohamed 1st University Oujda Nador Morocco Laboratory of SCiMATOP Chemistry Department Faculty of Sciences Semlalia Cadi Ayyad University Marrakech Morocco

The systematic method for constructing Lewis representations is a method for representing chemical bonds between atoms in a molecule. It uses symbols to represent the valence electrons of the atoms involved in the bond. Using a number of rules in a defined order, it is often better suited to complicated cases than the Lewis representation of atoms. This method allows us to determine the formal charge and oxidation number of each atom in the edifice more efficiently than other methods.

关键词： Systematic Method Lewis Representation Chemical Bond Formal Charge Oxidation Number

Ectopic Cornual Pregnancy: Case Report

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Obstetrics and Gynecology 2024年第5期14卷 847-854页

作者： Karim Lakraimi Myriem Sali Bouchra Fakhir abderrahim Aboulfallah Hamid Asmouki Karam Harou Ahlam Bassir Abderraouf Soummani Department of Obstetrics and Gynecology Med VI Mother and Child University of Cadi Ayyad Marrakech Morocco

This article showcases a clinical case of ectopic pregnancy lodged in the cornual. A pregnancy implanted in this location is a rarity, making it difficult to diagnose. By describing this case and screening of the literature, we explain the various diagnostic and therapeutic methods, both medical and surgical. Highlighting the importance of conservative treatment flush with the uterine horn, and conclude with some practical recommendations.

关键词： Horn Pregnancy Ultrasound Examination Laparotomy

A new and best approach for early detection of rotor and stator faults in induction motors coupled to variable loads

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers in Energy 2016年第2期10卷 176-191页

作者： abderrahim ALLAL Boukhemis CHETATE Research Laboratory on the Electrification of Industrial Enterprises University M'Hamed Bougara Boumerdes 35000 Institute of Sciences Technology Chahid Hamma Lakhdar University of El-Oued El-Oued39000 Algeria Research Laboratory on the Electrification of Industrial Enterprises University M'Hamed Bougara Boumerdes 35000 Algeria

Today, induction machines are playing, thanks to their robustness, an important role in world industries. Although they are quite reliable, they have become the target of various types of defects. Thus, for a long time, many research laboratories have been focusing their works on the theme of diagnosis in order to find the most efficient technique to predict a fault in an early stage and to avoid an unplanned stopping in the chain of production and costs ensuing. In this paper, an approach called Park＇s vector product approach （PVPA） was proposed which was endowed with a dominant sensitivity in the case in which there would be rotor or stator faults. To show its high sensitivity, it was compared with the classical methods such as motor current signature analysis （MCSA） and techniques studied in recent publications such as motor square current signature analysis （MSCSA）, Park＇s vector square modulus （PVSM） and Park-Hilbert （P-H）（PVSMp_H）. The proposed technique was based on three main steps. First, the three-phase currents of the induction motor led to a Park＇s vector. was calculated to show Secondly, the proposed PVPA the distinguishing spectral signatures of each default and specific frequencies. Finally, simulation and experimental results were presented to confirm the theoretical assumptions.

关键词： induction motor incipient broken bar,extended Park's vector approach spectral analysis interturn short-circuit Hilbert transform

New Results on PWARX Model Identification Based on Clustering Approach

在线全文

学校读者我要写书评

暂无评论

International Journal of Automation and computing 2014年第2期11卷 180-188页

作者： Zeineb Lassoued Kamel abderrahim Numerical Control of Industrial Processes National School of Engineers of GabesUniversity of GabesSt Omar Ibn-Khattab 6029 Gabes Tunisia

This paper deals with the problem of piecewise auto regressive systems with exogenous input(PWARX) model identification based on clustering solution. This problem involves both the estimation of the parameters of the affine sub-models and the hyper planes defining the partitions of the state-input regression. The existing identification methods present three main drawbacks which limit its effectiveness. First, most of them may converge to local minima in the case of poor initializations because they are based on the optimization using nonlinear criteria. Second, they use simple and ineffective techniques to remove outliers. Third, most of them assume that the number of sub-models is known a priori. To overcome these drawbacks, we suggest the use of the density-based spatial clustering of applications with noise(DBSCAN) algorithm. The results presented in this paper illustrate the performance of our methods in comparison with the existing approach. An application of the developed approach to an olive oil esterification reactor is also proposed in order to validate the simulation results.

关键词： Hybrid systems piecewise autoregressive systems with exogenous input(PWARX) model clustering identification density-based spatial clustering of applications with noise(DBSCAN) clustering technique experimental validation.

Performance of beacon safety message dissemination in Vehicular Ad hoc NETworks (VANETs)

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1990-2004页

作者： YOUSEFI Saleh FATHY Mahmood BENSLIMANE abderrahim Computer Engineering Faculty Iran University of Science and TechnologyNarmak Tehran 16846-13114 Tehran Iran Laboratoire d'Informatique d'Avignon LIA 339 chemin des Meinajaries BP 1228-84911 Avignon cedex 9 France

Currently, there is a growing belief that putting an IEEE 802.11-like radio into road vehicles can help the drivers to travel more safely. Message dissemination protocols are primordial for safety vehicular applications. There are two types of safety messages which may be exchanged between vehicles: alarm and beacon. In this paper we investigate the feasibility of deploying safety applications based on beacon message dissemination through extensive simulation study and pay special attention to the safety requirements. Vehicles are supposed to issue these messages periodically to announce to other vehicles their current situation and use received messages for preventing possible unsafe situations. We evaluate the performance of a single-hop dissemination protocol while taking into account the quality of service (QoS) metrics like delivery rate and delay. We realize that reliability is the main concern in beacon message dissemination. Thus, a new metric named effective range is defined which gives us more accurate facility for evaluating QoS in safety applications specifically. Then, in order to improve the performance, the effects of three parameters including vehicle's transmission range, message transmission's interval time and message payload size are studied. Due to special characteristics of the safety applications, we model the relationship between communication-level QoS and application-level QoS and evaluate them for different classes of safety applications. As a conclusion, the current technology of IEEE 802.11 MAC layer has still some challenges for automatic safety applications but it can provide acceptable QoS to driver assistance safety applications.

关键词： Safety applications Inter-vehicle communications Vehicular Ad hoc NETworks (VANETs) Application level QoS Effective range