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Vibration and stability of an aircraft tail under simultaneous primary-combined and internal resonance

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Theoretical & Applied Mechanics Letters 2011年第4期1卷 68-73页

作者： y.s.hamed W.A.A.El-Ganaini Department of Engineering Mathematics Faculty of Electronic EngineeringMenouf 32952Egypt Department of Mathematics and statistics Faculty of ScienceTaif UniversityTaifEl-HaweiahP.O.Box 88821974Kingdom of Saudi Arabia(KSA)

This paper adds a negative velocity feedback to the dynamical system of twin-tail aircraft to suppress the *** system is represented by two coupled second-order nonlinear differential equations having both quadratic and cubic *** system describes the vibration of an aircraft tail subjected to both multi-harmonic and multi-tuned *** method of multiple time scale perturbation is adopted to solve the nonlinear differential equations and obtain approximate solutions up to the third order *** stability of the proposed analytic solution near the simultaneous primary,combined and internal resonance is studied and its conditions are *** effect of different parameters on the steady state response of the vibrating system is studied and discussed by using frequency response *** different resonance cases are investigated numerically.

关键词： aircraft tail stability response active vibration control

Vibration Performance, stability and Energy Transfer of Wind Turbine Tower via Pd Controller

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Computers, Materials & Continua 2020年第8期64卷 871-886页

作者： y.s.hamed Ayman A.Aly B.saleh Ageel F.Alogla Awad M.Aljuaid Mosleh M.Alharthi Department of Mathematics and statistics Faculty of ScienceTaif UniversityTaifPO Box 888Saudi Arabia Department of Physics and Engineering Mathematics Faculty of Electronic EngineeringMenoufia UniversityMenoufPO Box 32952Egypt Department of Mechanical Engineering College of EngineeringTaif UniversityTaifPO Box 888Saudi Arabia Department of Mechanical Engineering Faculty of EngineeringAssiut UniversityAssiutPO Box 71516Egypt Department of Electrical Engineering College of EngineeringTaif UniversityTaifPO Box 888Saudi Arabia

In this paper,we studied the vibration performance,energy transfer and stability of the offshore wind turbine tower system under mixed *** method of multiple scales is utilized to calculate the approximate solutions of wind turbine *** proportional-derivative controller was applied for reducing the oscillations of the controlled *** the controller to single degree of freedom system equation is responsible for energy transfers in offshore wind turbine tower *** steady state solution of stability at worst resonance cases is studied and *** offshore wind turbine system behavior was studied numerically at its different parameters ***,the response and numerical results were obtained and *** stability is also analyzed using technique of phase plane and equations of frequency *** addition,the numerical results and comparison between analytical and numerical solutions were obtained with MAPLE and MATLAB algorithms.

关键词： Vibration control stability offshore wind turbine system energy transfer

Nonlinear study of the dynamic behavior of a string-beam coupled system under combined excitations

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Acta Mechanica sinica 2011年第6期27卷 1034-1051页

作者： y.s. hamed M. sayed D.-X. Cao W. Zhang Department of Engineering Mathematics Faculty of Electronic Engineering Menouf 32952 Egypt College of Mechanical Engineering Beijing University of Technology 100022 Beijing China Department of Mathematics and statistics Faculty of Science Taif University Taif E1-Haweiah EO. Box 888 Zip Code 21974 Kingdom of Saudi Arabia （KSA）

In this paper,the nonlinear dynamic behavior of a string-beam coupled system subjected to external,parametric and tuned excitations is *** governing equations of motion are obtained for the nonlinear transverse vibrations of the string-beam coupled system which are described by a set of ordinary differential equations with two degrees of *** case of 1：1 internal resonance between the modes of the beam and string,and the primary and combined resonance for the beam is *** method of multiple scales is utilized to analyze the nonlinear responses of the string-beam coupled system and obtain approximate solutions up to and including the second-order *** resonance cases are extracted and *** of the system is studied using frequency response equations and the phase-plane *** solutions are carried out and the results are presented graphically and *** effects of the different parameters on both response and stability of the system are *** reported results are compared to the available published work.

关键词： 1:1 internal resonance - string-beam - Multiple scales Chaotic response stability

Task scheduling Optimization in Cloud Computing Based on Genetic Algorithms

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Computers, Materials & Continua 2021年第12期69卷 3289-3301页

作者： Ahmed y.hamed Monagi H.Alkinani Faculty of Computers and Information Department of Computer ScienceSohag UniversitySohag82524Egypt Department of Computer science and Artificial Intelligence College of Computer Science and EngineeringUniversity of JeddahJeddah21959Saudi Arabia

Task scheduling is the main problem in cloud computing that reduces system performance;it is an important way to arrange user needs and perform multiple *** computing is the most popular technology nowadays and has many research potential in various areas like resource allocation,task scheduling,security,privacy,*** improve system performance,an efficient task-scheduling algorithm is *** task-scheduling algorithms focus on task-resource requirements,CPU memory,execution time,and execution *** this paper,a task scheduling algorithm based on a Genetic Algorithm(GA)has been presented for assigning and executing different *** proposed algorithm aims to minimize both the completion time and execution cost of tasks and maximize resource *** evaluate our algorithm’s performance by applying it to two examples with a different number of tasks and *** first example contains ten tasks and four processors;the computation costs are generated *** last example has eight processors,and the number of tasks ranges from twenty to seventy;the computation cost of each task on different processors is generated *** achieved results show that the proposed approach significantly succeeded in finding the optimal solutions for the three objectives;completion time,execution cost,and resource utilization.

关键词： Cloud computing task scheduling genetic algorithm optimization algorithm

surface metal-matrix composites based on AZ91 magnesium alloy via friction stir processing:A review

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International Journal of Minerals,Metallurgy and Materials 2023年第7期30卷 1278-1296页

作者： hamed Mirzadeh school of Metallurgy and Materials Engineering College of EngineeringUniversity of TehranTehranIran

This monograph presents an overview of friction stir processing(FsP)of surface metal-matrix composites(MMCs)using the AZ91 magnesium *** reported results in relation to various reinforcing particles,including silicon carbide(siC),alumina(Al_(2)O_(3)),quartz(siO_(2)),boron carbide(B_(4)C),titanium carbide(TiC),carbon fiber,hydroxyapatite(HA),in-situ formed phases,and hybrid reinforcements are ***91 composite fabricating methods based on FsP are explained,including groove filling(grooving),drilled hole filling,sandwich method,stir casting followed by FsP,and formation of in-situ *** effects of introducing second-phase particles and FsP process parameters(e.g.,tool rotation rate,traverse speed,and the number of passes)on the microstructural modification,grain refinement,homogeneity in the distribution of particles,inhibition of grain growth,mechanical properties,strength–ductility trade-off,wear/tribological behavior,and corrosion resistance are ***,useful suggestions for future work are proposed,including focusing on the superplasticity and superplastic forming,metal additive manufacturing processes based on friction stir engineering(such as additive friction stir deposition),direct FsP,stationary shoulder FsP,correlation of the dynamic recrystallization(DRX)grain size with the Zener–Hollomon parameter similar to hot deformation studies,process parameters(such as the particle volume fraction and external cooling),and common reinforcing phases such as zirconia(ZrO_(2))and carbon nanotubes(CNTs).

关键词： surface composites magnesium alloys friction stir processing severe plastic deformation thermomechanical processing

Minimum Reservoir Water Level in Hydropower Dams

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Chinese Journal of Mechanical Engineering 2017年第4期30卷 1017-1024页

作者： hamed sarkardeh Department of Civil Engineering Hakim Sabzevari UniversitySabzevarIran

Vortex formation over the intakes is an unde- sirable phenomenon within the water withdrawal process from a dam reservoir. Calculating the minimum operating water level in power intakes by empirical equations is not a safe way and sometimes contains some errors. Therefore, current method to calculate the critical submergence of a power intake is construction of a scaled physical model in parallel with numerical model. In this research some pro- posed empirical relations for prediction of submergence depth in power intakes were validated with experimental data of different physical and numerical models of power intakes. Results showed that, equations which involved the geometry of intake have better correspondence with the experimental and numerical data.

关键词： Power intake. Vortex Critical submergence Physical and numerical models Empirical equations

Optimization Task scheduling Using Cooperation search Algorithm for Heterogeneous Cloud Computing systems

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Computers, Materials & Continua 2023年第1期74卷 2133-2148页

作者： Ahmed y.hamed M.Kh.Elnahary Faisal s.Alsubaei Hamdy H.El-sayed Department of Computer science Faculty of Computers and Artificial IntelligenceSohag UniversitySohag82524Egypt Department of Cybersecurity College of Computer Science and EngineeringUniversity of JeddahJeddah21959Saudi Arabia

Cloud computing has taken over the high-performance distributed computing area,and it currently provides on-demand services and resource polling over the *** a result of constantly changing user service demand,the task scheduling problem has emerged as a critical analytical topic in cloud *** primary goal of scheduling tasks is to distribute tasks to available processors to construct the shortest possible schedule without breaching precedence *** and schedules of tasks substantially influence system operation in a heterogeneous multiprocessor *** diverse processes inside the heuristic-based task scheduling method will result in varying makespan in the heterogeneous computing *** a result,an intelligent scheduling algorithm should efficiently determine the priority of every subtask based on the resources necessary to lower the *** research introduced a novel efficient scheduling task method in cloud computing systems based on the cooperation search algorithm to tackle an essential task and schedule a heterogeneous cloud computing *** basic idea of thismethod is to use the advantages of meta-heuristic algorithms to get the optimal *** assess our algorithm’s performance by running it through three scenarios with varying numbers of *** findings demonstrate that the suggested technique beats existingmethods NewGenetic Algorithm(NGA),Genetic Algorithm(GA),Whale Optimization Algorithm(WOA),Gravitational search Algorithm(GsA),and Hybrid Heuristic and Genetic(HHG)by 7.9%,2.1%,8.8%,7.7%,3.4%respectively according to makespan.

关键词： Heterogeneous processors cooperation search algorithm task scheduling cloud computing

Microstructural evolution and mechanical properties of friction stir-welded C71000 copper–nickel alloy and 304 austenitic stainless steel

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International Journal of Minerals,Metallurgy and Materials 2018年第11期25卷 1294-1303页

作者： hamed Jamshidi Aval Department of Materials and Industrial Engineering Babol Noshirvani University of Technology

Dissimilar joints comprised of copper–nickel and steel alloys are a challenge for manufacturers in modern industries, as these metals are not thermomechanically or chemically well matched. The present study investigated the effects of tool rotational speed and linear speed on the microstructure and mechanical properties of friction stir-welded C71000 copper–nickel and 340 stainless steel alloys using a tungsten carbide tool with a cylindrical pin. The results indicated that a rotational-to-linear speed ratio of 12.5 r/mm did not cause any macro defects, whereas some tunneling defects and longitudinal cracks were found at other ratios that were lower and higher. Furthermore, chromium carbide was formed on the grain boundaries of the 304 stainless steel near the shoulder zone and inside the joint zone, directing carbon and chromium penetration toward the grain boundaries. Tensile strength and elongation percentages were 84% and 65% of the corresponding values in the copper–nickel base metal, respectively.

关键词： dissimilar friction stir welding copper–nickel alloy austenitic stainless steel microstructure mechanical properties

Optimal state Estimation and Fault Diagnosis for a Class of Nonlinear systems

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IEEE/CAA Journal of Automatica sinica 2020年第2期7卷 517-526页

作者： hamed Kazemi Alireza yazdizadeh Department of Electrical Engineering Shahid Beheshti UniversityTehran ***Iran

This study proposes a scheme for state estimation and,consequently,fault diagnosis in nonlinear ***,an optimal nonlinear observer is designed for nonlinear systems subject to an actuator or plant *** utilizing Lyapunov's direct method,the observer is proved to be optimal with respect to a performance function,including the magnitude of the observer gain and the convergence *** observer gain is obtained by using approximation of Hamilton-Jacobi-Bellman(HJB)*** approximation is determined via an online trained neural network(NN).Next a class of affine nonlinear systems is considered which is subject to unknown disturbances in addition to fault *** this case,for each fault the original system is transformed to a new form in which the proposed optimal observer can be applied for state estimation and fault detection and isolation(FDI).simulation results of a singlelink flexible joint robot(sLFJR)electric drive system show the effectiveness of the proposed methodology.

关键词： Differential geometry fault detection and isolation(FDI) fault diagnosis neural network(NN) nonlinear observer and filter design optimal state estimation