检索结果-南通市图书馆

Influence of heat treatment on microstructure and tribological properties of flame spraying Fe–Ni–Al alloy coating

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2018年第3期25卷 473-481页

作者： Youcef Mouadji Mohand Amokrane Bradai Rassim Younes Abdelhamid Sad-eddine abderrahim benabbas National Polytechnic School of Constantine Department of Mechanical Engineering University of Constantine Laboratory of Mechanics Materials and Energetic Faculty of Technology University of Bejaia Laboratory Processes for Materials Energy Water and Environment Faculty of Science and TechnologyUniversity of Bouira

The Fe-based coatings in powder form were deposited on a steel type E335 by flame spraying *** effects of the post heat treatment on the microstructure and the mechanical properties of sprayed coatings were *** heat treatment was conducted in a furnace in air at 623 K,823 K and 1023 K for 1 h and then cooled in *** results showed that with the increase of annealing temperature,the microstructure of coating treated at 823 K and 1023 K had several changes as follows:the reduction of porosity,formation of carbides and *** was found that the solid solution FCC(Fe,Ni),intermetallic compound AlFe3 and carbides[Fe,C]were the main phases for coatings as-sprayed and treated at 623 K and while iron carbide,molybdenum carbide and oxide as Fe3O4 became the main phases and reinforced the solid solution FCC(Fe,Ni)phase for annealed coatings at 823 ***,it was observed the disappearance of molybdenum carbide and oxide Fe3O4 at 1023 *** coating annealed at 823 K exhibited an excellent wear resistance than the as-sprayed and annealed coatings at 623 K and 1023 K and shows the lower wear rate than another coating treated or as sprayed.

关键词： thermal spray coatings post heat treatment microstructure wear

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

在线全文

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

On stability behaviors of 5D M-theory black objects

在线全文

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

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

Predictive Control Based on Fuzzy Supervisor for PWARX Hybrid Model

在线全文

学校读者我要写书评

暂无评论

International Journal of Automation and computing 2019年第5期16卷 683-695页

作者： Olfa Yahya Zeineb Lassoued Kamel abderrahim Numerical Control of Industrial Processes National Engineering School of Gabes University of Gabes

In this paper, the problem of hybrid model predictive control(HMPC) strategy based on fuzzy supervisor for piecewise autoregressive with exogenous input(PWARX) models is addressed. We first represent the nonlinear behavior of the system with a PWARX model. Then, we transform the obtained PWARX model into a mixed logical dynamic(MLD) model in order to apply the proposed predictive control which is able to stabilize such systems along desired reference trajectories while satisfying operating ***, we propose to introduce a fuzzy supervisor allowing the readjustment of the HMPC tuning parameters in order to maintain the desired performance. Simulation and experimental results are presented to illustrate the effectiveness of the proposed approach.

关键词： Nonlinear control hybrid systems mixed logical dynamic(MLD) model predictive control fuzzy supervisor

Prediction of elastic and acoustic behaviors of calcarenite used for construction of historical monuments of Rabat, Morocco

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 74-83页

作者： Abdelaali Rahmouni abderrahim Boulanouar abderrahim Samaouali Mohamed Boukalouch Yves Géraud Jamal Sebbani Laboratory of Thermodynamics Department of Physics Faculty of Science Mohammed V University P.O. Box 1014 Rabat Morocco University of Lorraine ENSG UMR 7359-GeoRessources Nancy Cedex France

Natural materials(e.g. rocks and soils) are porous media, whose microstructures present a wide *** generally consist of a heterogeneous solid phase and a porous phase which may be fully or partially saturated with one or more fluids. The prediction of elastic and acoustic properties of porous materials is very important in many fields, such as physics of rocks, reservoir geophysics, civil engineering, construction field and study of the behavior of historical monuments. The aim of this work is to predict the elastic and acoustic behaviors of isotropic porous materials of a solid matrix containing dry, saturated and partially saturated spherical pores. For this, a homogenization technique based on the Morie Tanaka model is presented to connect the elastic and acoustic properties to porosity and degree of water saturation. Non-destructive ultrasonic technique is used to determine the elastic properties from measurements of P-wave velocities. The results obtained show the influence of porosity and degree of water saturation on the effective properties. The various predictions of Morie Tanaka model are then compared with experimental results for the elastic and acoustic properties of calcarenite.

关键词： Calcarenite Porous media Homogenization Morie Tanaka model Porosity Elastic properties Acoustic properties Degree of water saturation

Effect of an Inclined Slots on the Power Consumption and Vortices Size in a Rushton Turbine Agitated Tank

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2023年第6期36卷 261-276页

作者： Sarra Youcefi Mohamed Bouzit Abdelkader Youcefi abderrahim Mokhefi Laboratory of Applied Mechanics Department of Mechanical EngineeringUniversity of Sciences and Technology of OranOran 31000Algeria Laboratory of Maritime Sciences and Engineering Department of Marine EngineeringUniversity of Science and Technology of OranOran 31000Algeria Laboratory of Aeronautics and Propulsion Systems Department of Mechanical EngineeringUniversity of Science and Technology of OranOran 31000Algeria Laboratory of Mechanics Modeling and ExperimentationDepartment of Mechanical EngineeringTahri Mohamed University of BecharBechar 08000Algeria

Mechanical agitation in baffled vessels with turbines plays a vital role in achieving homogeneous fluid mixing and promoting various transfer ***,designing vessels with optimal energy efficiency and flow dynamics is essential to enhance operational performance and eliminate flow ***,the present research focuses on a numerical investigation of the impact of inclined slots with different angles installed at the side-wall of a cylindrical vessel equipped with a Rushton *** study explores power consumption and vortex size while considering various rotation directions of the impeller with different rotation *** numerical simulations are conducted for Reynolds numbers ranging from 104 to 105,using the RANS k-εturbulence model to govern the flow inside the stirred vessel,accounting for mass and momentum *** results have shown that the installation of slots reduces power consumption and vortex size compared to conventional vessel ***,increasing the slot angle from 0 to 32.5°further reduces energy consumption and vortex size,especially with negative rotation *** the other hand,increasing the Reynolds numbers leads to a decrease in power consumption and an increase in vortex *** present research therefore proposes a design for con-structing Rushton-turbine stirred vessels offering optimal operation,characterized by reduced energy consumption and minimized vortex size.

关键词： Mixing Stirred tank Rushton turbine Inclined slots Hydrodynamic Power consumption Vortices size

A Study on the Second Order Tangent Bundles over Bi-Kählerian Manifolds

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of Mathematics,Series B 2024年第5期45卷 777-804页

作者： Nour Elhouda DJAA Aydin GEZER abderrahim ZAGANE Relizane University Faculty of Sciences and TechnologyDepartment of MathematicsAlgeria Ataturk University Faculty of ScienceDepartment of Mathematics25240Erzurum-Turkey

This paper aims to study the Berger type deformed Sasaki metric g_(BS)on the second order tangent bundle T^(2)M over a bi-Kählerian manifold *** authors firstly find the Levi-Civita connection of the Berger type deformed Sasaki metric g_(BS)and calculate all forms of Riemannian curvature tensors of this ***,they study geodesics on the second order tangent bundle T^(2)M and bi-unit second order tangent bundle T^(2)_(1,1)M,and characterize a geodesic of the bi-unit second order tangent bundle in terms of geodesic curvatures of its projection to the ***,they present some conditions for a sectionσ:M→T^(2)M to be harmonic and study the harmonicity of the different canonical projections and inclusions of(T^(2)M,g_(BS)).Moreover,they search the harmonicity of the Berger type deformed Sasaki metric g_(BS)and the Sasaki metric g_(S) with respect to each other.

关键词： Berger type deformed Sasaki metric Bi-Kählerian structure Geodesics Harmonicity Riemannian curvature tensor Second order tangent bundle