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Elastic-viscoplastic constitutive model for capturing the mechanical response of polymer composite at various strain rates

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Journal of Materials Science & Technology 2020年第22期54卷 12-17页

作者： Shahzad fateh Ali Jitang Fan State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing700087China

Recently, polymer composites, consisting of hard segments and soft segments blend, attract a broad research interest because of the high flow stress and large deformation under a high rate loading. They display an outstanding energy absorption capability for impact resistant engineering. In this paper,a physics-based elastic-viscoplastic constitutive model is developed which accounts the activation of molecular chains motion at different segments upon an applied stress as well as the rate dependency of mechanical properties. Accordingly, finite element simulations are conducted to derive the mechanical performance at various strain rates. It involves the linearly elastic deformation to yielding, softening behavior with a slight decrease of stress, plastic flow at a plateau stress accompanied by a considerable straining, densification with a fast increase of stress. The results achieved from model simulations match well with these obtained by experiments and the mechanical response in the strain rate range from 0.0001 s^(-1) to 8000 s^(-1) can be captured by this model. Finally, energy absorption capability of the polymer composite is discussed, and the physical mechanisms in material science are addressed by post-loading analysis. This work is full of interest to develop the constitutive model for designing the impact-resistant polymers and illustrating the dynamic mechanical response, which will promote the application of light-weight transparent protection structure against a high-speed impact.

关键词： Polymer composite Constitutive model Strain rate Mechanical behavior

Design of Radial Basis Function Network Using Adaptive Particle Swarm Optimization and Orthogonal Least Squares

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Journal of Software Engineering and Applications 2010年第7期3卷 704-708页

作者： Majid Moradi Zirkohi mohammad mehdi fateh Ali Akbarzade 不详

This paper presents a two-level learning method for designing an optimal Radial Basis Function Network (RBFN) using Adaptive Velocity Update Relaxation Particle Swarm Optimization algorithm (AVURPSO) and Orthogonal Least Squares algorithm (OLS) called as OLS-AVURPSO method. The novelty is to develop an AVURPSO algorithm to form the hybrid OLS-AVURPSO method for designing an optimal RBFN. The proposed method at the upper level finds the global optimum of the spread factor parameter using AVURPSO while at the lower level automatically constructs the RBFN using OLS algorithm. Simulation results confirm that the RBFN is superior to Multilayered Perceptron Network (MLPN) in terms of network size and computing time. To demonstrate the effectiveness of proposed OLS-AVURPSO in the design of RBFN, the Mackey-Glass Chaotic Time-Series as an example is modeled by both MLPN and RBFN.

关键词： Radial Basis Function Network Orthogonal Least Squares Algorithm Particle Swarm Optimization Mackey-Glass Chaotic Time-Series

Frequency-Domain Estimation of Continuous-Time Bilinear Processes

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Communications in Mathematics and Statistics 2021年第4期9卷 379-403页

作者： Abdelouahab Bibi fateh Merahi Department of Mathematics Larbi Ben M’hidi UniversityOum El BouaghiAlgeria Department of Mathematics Abbes Laghrour UniversityBP 1252 Route de Batna40004 KhenchelaAlgeria

In this paper,we study in frequency domain someprobabilistic and statistical properties of continuous-time version of the well-known bilinear processes driven by a standard Brownian *** class of processes which encompasses many commonly used processes in the literature was defined as a nonlinear stochastic differential equation which has raised considerable interest in the last few ***,the L_(2)-structure of the process is studied and its covariance function is *** structures will lead to study the strong consistency and asymptotic normality of the Whittle estimates of the unknown parameters involved in the *** sample properties are also considered through Monte Carlo *** end,the model is then used to model the exchanges rate of the Algerian Dinar against the US dollar.

关键词： Continuous-time bilinear processes Whittle estimator Consistency Asymptotic normality

Effect of Nb on Austenite Formation and Decomposition in an X80 Linepipe Steel

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Journal of Iron and Steel Research International 2011年第S1期18卷 658-663页

作者： fateh Fazeli Matthias Militzer The Centre for Metallurgical Process Engineering The University of British Columbia VancouverBCCanada V6T 1Z 4

Advanced high strength steels for pipeline applications,e.g.X80 grades,have complex microstructures and are frequently microalloyed with *** the hot rolled product it is sought to have Nb precipitated as Nb(CN).However,when processing these steels Nb may be in solution and critically affects the microstructure evolution,*** decomposition on the run-out table of a hot ***,microstructure changes in the heat affected zone (HAZ) during girth welding of these linepipe steels may occur with Nb precipitated or in *** the HAZ,depending on welding procedures,the material undergoes a number of austenite formation and decomposition cycles and the amount of Nb in solution varies along these *** selected positions of the HAZ,thermal cycles peak at the intercritical region and the partial formation of austenite and subsequent decomposition constitutes additional *** reliable process models for run-out table cooling and the HAZ hinges on an accurate tracking of microstructure evolution,which is strongly influenced by the amount of Nb in *** present study provides more insight into the effect of Nb on austenite formation and ***,a novel experimental methodology is presented to measure quantitatively the effect of Nb on transformation temperatures pertinent to austenite decomposition,notably ferrite.A model for ferrite formation that accounts for solute drag of Nb is proposed to describe the experimental ***,an experimental study will be presented to quantify the effect of Nb in and out of solution on austenite formation in the intercritical *** is found that the morphology of intercritical austenite,as well as the kinetics of its formation is strongly affected by the starting microstructure and the state of Nb.

关键词： Effect of Nb on Austenite Formation and Decomposition in an X80 Linepipe Steel HAZ

A Cryptographic-Based Approach for Electricity Theft Detection in Smart Grid

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Computers, Materials & Continua 2020年第4期63卷 97-117页

作者： Khelifi Naim Benahmed Khelifa Bounaama fateh Laboratory of Energetic in Arid Zones(ENERGARID) Department of Electrical EngineeringFaculty of TechnologyTahri Mohammed University of BecharBechar08000Algeria Department of Mathematics and Computer Science Faculty of Exact SciencesTahri Mohammed University of BecharBechar08000Algeria

In order to strengthen their security issues,electrical companies devote particular efforts to developing and enhancing their fraud detection techniques that cope with the information and communication technologies integration in smart grid *** been treated earlier by several researchers,various detection schemes adapted from attack models that benefit from the smart grid topologies weaknesses,aiming primarily to the identification of suspicious incoming *** meshes have been extensively used in smart grid communication architectures due to their facility,lightness of conception and low cost installation;however,the communicated packets are still exposed to be intercepted maliciously in order either to falsify pertinent information like the smart meter readings,or to inject false data instead,aiming at electricity theft during the communication *** this reason,this paper initiates a novel method based on RSA cryptographic algorithm to detect electricity fraud in smart *** new method consists of generating two different cryptograms of one electricity measurement before sending,after which the recipient is used to find the same value after decrypting the two cyphers in a normal ***,a fraudulent manipulation could occur during the transmission *** presented method allows us to kill two birds with one ***,satisfactory outcomes are shown:the algorithm accuracy reaches 100%,from one hand,and the privacy is protected thanks to the cryptology concept on the other hand.

关键词： Electricity consumption fraud detection RSA algorithm security smart grid

A Macro-Mechanical Study for Capturing the Dynamic Behaviors of a Rate-Dependent Elastomer and Clarifying the Energy Dissipation Mechanisms at Various St rain Rates

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Acta Mechanica Solida Sinica 2022年第2期35卷 228-238页

作者： Shahzad fateh Ali Jitang Fan Jianqing Feng Xiangquan Wei State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Aerospace System Engineering shanghai Shanghai 201109China

A strain-rate-sensitive polyurethane elastomer is numerically investigated to reveal improved impact characteristics and analyze the concerned rate dependencies and dynamic energy dissipation features.A physical constitutive model in view of amorphous molecular struc-ture of the elastomer is proposed by relating the macro-mechanical behaviors to micro-structural changes through molecular transitions and flow *** distinct relaxation processes are considered because of entangled molecular net works,with each possessing a unique activation *** calibration with experimental data,finite element simulations based on the model are *** to the loading rate,the structural entropy of molecular chain entanglements,rate-dependent yielding,plateau flow and densification are well predicted by the *** investigations are extended further regarding the material recoverability and accordingly,strain energy absorptions are illustrated.A power law function is proposed for designing the energy absorption relation to the applied loading ***,the inherent mechanisms causing the dynamic energy absorptions are analyzed with notable clarifications of post-experimental observations obtained via scanning elec Iron microscopy.

关键词： Elastomer Constitutive model Energy absorption Ratedependent Scanning electron microscopy

Organic functional materials based buffer layers for efficient perovskite solar cells

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Chinese Chemical Letters 2017年第3期28卷 503-511页

作者： fateh Ullah Hongzheng Chen Chang-Zhi Li MOE Key Laboratory of Macromolecular Synthesis and Functionalization State Key Laboratory of Silicon Materials Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027 China

In this review, we highlight the recent development of organic π-functional materials as buffer layers in constructing efficient perovskite solar cells（PVSCs）. By following a brief introduction on the PVSC development, device architecture and material design features, we exemplified the exciting progresses made in field by exploiting organic π-functional materials based hole and electron transport layers（HTLs and ETLs） to enable high-performance PVSCs.

关键词： Perovskite solar cells Organic functional material Hole transport layer Electron transport layer Power conversion efficiency

The HARBINGER of endoscopic therapy in critically-ill patients with upper GI bleeding

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Gastroenterology Report 2021年第1期9卷 88-89,I0003页

作者： fateh Bazerbachi Masayasu Horibe Division of Gastroenterology Department of MedicineMassachusetts General Hospital55 Fruit StreetBostonMAUSA Department of Internal Medicine Division of Gastroenterology and HepatologyKeio University School of MedicineShinjuku-kuTokyoJapan Division of Gastroenterology and Hepatology Mayo Clinic200 First St SWRochesterMNUSA

We read with great interest the study by Rao et al.[1]Rao and colleagues showed that the Rockall score,Glasgow-Blatchford score(GBS)and AIMS65 are poorly predictive of 30-day mortality,or the need for endoscopic intervention in intensive care unit(ICU)patients with an upper GI bleed(UGIB).The Rockall[2]score and AIMS65[3]were developed for predicting mortality,whereas the GBS[4]was developed for predicting composite outcomes(The need for a blood transfusion or intervention to control bleeding,rebleeding,or death)We were not surprised to see that these scores were poor predictors of endoscopic intervention,as they were not designed to predict high-risk endoscopic stigmata(HRS),which is arguably a very meaningful endpoint to determine the need for endoscopic intervention.

关键词：胃肠出血上消化道出血内镜治疗 Glasgow AIMS

Modeling and control of a permanent magnet synchronous generator dedicated to standalone wind energy conversion system

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Frontiers in Energy 2016年第2期10卷 155-163页

作者： Louar fateh Ouari AHMED Omeiri AMAR Djellad ABDELHAK Bouras LAKHDAR Department of Electrical Engineering University of Badji MokhtarAnnaba 23000 Algeria Department of Electrical Engineering University of 20 Aout 1955Skikda Skikda 21000 Algeria

The interest for the use of renewable energies has increased, because of the increasing concerns of the environmental problems. Among renewable energies, wind energy is now widely used. Wind turbines based on an asynchronous generator with a wound rotor present the inconvenience of requiring a system of tings and brooms and a multiplier, inferring significant costs of maintenance. To limit these inconveniences, certain manufacturers developed wind turbines based on synchronous machines with large number of pairs of poles coupled directly with the turbine, avoiding using the multiplier. If the generator is equipped with permanent magnets, the system of rings and brooms is eliminated. The control of the permanent magnet synchronous generator （PMSG） can be affected with the implementation of various techniques of control. This paper presented a new approach mainly based on the control strategy of power production system based on the PMSG. In fact, a mathematical model that simulates the Matlab chain was established with the introduction of control techniques, such as direct control of the torque （DTC） to control the load side converter （LSC）, the control of the speed of the turbine and the DC-bus voltage ensured by PI regulators. To show the performance of the correctors used, some simulation results of the system were presented and analyzed.

关键词： wind turbine permanent magnet synchronous