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health monitoring of time-varying stochastic structures by latent components and fuzzy expert system

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Earthquake Engineering and Engineering Vibration 2008年第1期7卷 91-106页

作者： m. m. Ettefagh m. h. Sadeghi Vibration and modal Analysis Laboratory Department of Mechanical Engineering University of Tabriz Tabriz 51666 Iran

In this paper, a novel parametric model-based decomposition method is proposed for structural health monitoring of time-varying structures. For this purpose, the advanced Functional-Series Time-dependent Auto Regressive moving Average （FS-TARmA） technique is used to estimate the parameters and innovation variance used in the parametric signal decomposition scheme. Additionally, a unique feature extraction and reduction method based on the decomposed signals, known as Latent Components （LCs）, is proposed. To evaluate the efficiency of the proposed method, numerical simulation and an experimental study in the laboratory were conducted on a time-varying structure, where various types of damage were introduced. The Fuzzy Expert System （FES） was used as a classification toot to demonstrate that the proposed method successfully identifies different structural conditions when compared with other methods based on non-reduced and ordinary feature extraction.

关键词： parametric modeling signal decomposition feature extraction/reduction fuzzy classification

Effect of rare earth elements and their oxides on tribo-mechanical performance of laser claddings:A review

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Journal of Rare Earths 2016年第6期34卷 549-564页

作者： m.m.Quazi m.A.Fazal A.S.m.A.haseeb Farazila Yusof h.h.masjuki A.Arslan Department of mechanical Engineering Faculty of EngineeringUniversity of Malaya50603 Kuala LumpurMalaysia Center for Energy Science Uni-versity of Malaya50603 Kuala LumpurMalaysia Centre of Advanced manufacturing and material Processing(AmmP Centre) University of Malaya50603 Kuala LumpurMalaysia

Laser cladding is a promising photon-based surface engineering technique broadly utilized for fabricating harder and wear resistant composite coatings. In spite of excellent properties, the practical applications of laser claddings are relatively restricted when compared with well-established coating techniques because of their inherent defects identified as cracks, pores and inclusions. Substantial evidence suggests that the incorporation of an appropriate amount of rare earth in laser claddings can remarkably prevent these defects. Additionally, the presence of rare earth in laser claddings can notably enhance tribo-mechanical properties such as surface hardness, modulus of elasticity, fracture toughness, friction coefficient and wear rate. In this literature review, the effect of rare earth in reducing dilution and cracks susceptibility of laser claddings in addition to microstructural refinement attained was examined. mechanical and tribological properties of these claddings along with their underlying mechanism were discussed in detail. Finally, this article summarizes current applications of laser claddings based on rare earth and was concluded with future research directions.

关键词： laser cladding rare earth elements microstructure tribo-mechanical properties

Thomson effect with hyperbolic two-temperature on magneto-thermo-visco-elasticity

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Applied mathematics and mechanics(English Edition) 2021年第9期42卷 1311-1326页

作者： A.m.ALhARBI m.I.A.OThmAN h.m.ATEF Department of mathematics College of ScienceTaif UniveristyTaif 21944Saudi Arabia Department of mathematics Faculty of ScienceZagazig UniversityZagazig 44519Egypt Department of mathematics Faculty of ScienceDamanhur UniversityDamanhur 22511Egypt

The study considers a homogeneous isotropic thermo-visco-elastic solid with hyperbolic two-temperature to cope up with its two-dimensional(2 D)*** heat conduction equation is influenced by the Thomson ***-Shulman’s theory is used to modify the basic governing equations.A method called"normal mode analysis"is utilized to attain the magnetic field,stress,conductive and thermodynamic temperature,and displacement ***,a number of numerical calculations are performed and discussed to understand the impact of hyperbolic two-temperatures,Thomson parameter,and viscosity on the material mentioned above.

关键词： thermo-visco-elasticity magnetic field hyperbolic two-temperature Lord-Shulman’s theory Thomson coefficient normal mode analysis

Coexistence and fluctuations phenomena with Davidson-like potentials in quadrupoleoctupole deformed nuclei

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Communications in Theoretical Physics 2021年第3期73卷 105-118页

作者： m m hammad W h mansour E m El-maghraby h A motaweh Ayman A Aly Faculty of Science Mathematics DepartmentDamanhour UniversityEgypt Faculty of Science Physics DepartmentDamanhour UniversityEgypt

The energy spectra of three types of two-dimensional potentials(we will call them‘Davidson-like potentials’(DLPs)),characterized by four minima separated by barriers,are *** predictions for spectra and wave functions are obtained by using the nine-point finite-difference *** these potentials,with the existence of a single configuration,a transition of spectra,as a function of barrier height,is covered from tunneling splitting modes to fluctuations phenomena,with equal peaks wave functions,crossing to the spectra of purely anharmonic oscillator potentials(AOPs).A different type of phase transition occurs when two(or more)configurations *** the change of the parameters,a transition of spectra is covered from coexistence phenomena of two distinct quantum tunneling modes to fluctuations phenomena,with unequal peaks wave functions,crossing to the spectra of purely *** DLPs,a particular application of the coherent quadropole-octupole model to describe energy bands with alternating parity of the nuclei^(100)mo,^(146,148)Nd,^(148,150)Sm,^(220)Ra,^(220,222)Rn,and^(220,222)Th is *** global parametrization of the model for the selected nuclei is achieved.

关键词： quantum phase transitions fluctuations phenomena coherent quadrupole-octupole motion model coexistence phenomena

Active Force with Fuzzy Logic Control of a Two-Link Arm Driven by Pneumatic Artificial muscles

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Journal of Bionic Engineering 2011年第4期8卷 474-484页

作者： h. Jahanabadi m. mailah m. Z. md Zain h. m. hooi Department of System Dynamics and Control Faculty of Mechanical Engineering Universiti Teknologi Malaysia 81310 UTM Johor Bahru Skudai Johor Malaysia

In this paper, the practicality and feasibility of Active Force Control （AFC） integrated with Fuzzy Logic（AFCAFL） applied to a two link planar arm actuated by a pair of Pneumatic Artificial muscle （PAm） is investigated. The study emphasizes on the application and control of PAm actuators which may be considered as the new generation of actuators comprising fluidic muscle that has high-tension force, high power to weight ratio and high strength in spite of its drawbacks in the form of high nonlinearity behaviour, high hysteresis and time varying parameters. Fuzzy Logic （FL） is used as a technique to estimate the best value of the inertia matrix of robot arm essential for the AFC mechanism that is complemented with a conventional Propor- tional-Integral-Derivative （PID） control at the outermost loop. A simulation study was first performed followed by an experi- mental investigation for validation. The experimental study was based on the independent joint tracking control and coordinated motion control of the arm in Cartesian or task space. In the former, the PAm actuated arm is commanded to track the prescribed trajectories due to harmonic excitations at the joints for a given frequency, whereas for the latter, two sets of trajectories with different loadings were considered. A practical rig utilizing a hardware-In-The-Loop Simulation （hILS） configuration was developed and a number of experiments were carried out. The results of the experiment and the simulation works were in good agreement, which verified the effectiveness and robustness of the proposed AFCAFL scheme actuated by PAm.

关键词： pneumatic artificial muscle active force control fuzzy estimator hardware-in-the-loop simulation

Crashworthiness performance of hybrid kenaf/glass fiber reinforced epoxy tube on winding orientation effect under quasi-static compression load

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Defence Technology（防务技术） 2020年第5期16卷 1051-1061页

作者： A.B.m.Supian S.m.Sapuan m.Y.m.Zuhri E.S.Zainudin h.h.Ya Advanced Engineering materials and Composites Research Centre Department of Mechanical and Manufacturing EngineeringUniversiti Putra Malaysia43400UPM SerdangSelangorMalaysia Laboratory of Biocomposite Technology Institute of Tropical Forestry and Forest Products(INTROP)Universiti Putra Malaysia43400UPM SerdangSelangorMalaysia Department of mechanical Engineering Universiti Teknologi Petronas32610Seri IskandarPerakMalaysia

This research was aimed to study the effect winding orientation on the crashworthiness performance of hybrid *** specimens tested under quasi-static compression load involve of three winding parameters(q?30,45and 70)of hybrid kenaf/glass fiber reinforced epoxy and glass fiber reinforced epoxy as contrast *** automated filament winding technique has been used in fabrication of hybrid and non-hybrid composite tube and crashworthiness performance was investigated *** effects of winding orientation on energy absorption capabilities and crashworthiness characteristic were investigated through quasi-static compression load and the result are compared with the glass fiber composite tube to justify the capability of hybrid natural/synthetic as energy absorption *** samples proved to enhancing the progressive crushing capability as combination of local buckling,delaminate and brittle fracturing as progressive crushing *** the view of winding orientation aspect,the results of high winding orientation of hybrid composite tube elevated the crush load efficiency,specific energy absorption and energy absorption capability compared to glass composite tube(GFRP).The hybrid kenaf/glass composite tube with high winding orientation showed the best winding orientation to enhance the energy absorber characteristics as energy absorption application.

关键词： composite laminate winding

Q-Switched Ytterbium-Doped Fiber Laser Using Black Phosphorus as Saturable Absorber

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Chinese Physics Letters 2016年第5期33卷 54-57页

作者： A.h.h.Al-masoodi m.h.m.Ahmed A.A.Latiff h.Arof S.W.harun Department of Electrical Engineering Faculty of EngineeringUniversity of Malaya Photonics Research Center University of Malaya

We demonstrate a Q-switched ytterbium-doped fiber laser （YDFL） using a newly developed multi-layer black phosphorous （BP） saturable absorber （SA）. The BP SA is prepared by mechanically exfoliating a BP crystal and sticking the acquired BP flakes onto a scotch tape. A small piece of the tape is then placed between two ferrules and incorporated in a YDFL cavity to achieve a stable Q-switched operation in a 1.0 μm region. The laser has a pump threshold of 55.1 mW, a pulse repetition rate that is tunable from 8.2 to 32.9 khz, and the narrowest pulse width of 10.8 μs. The highest pulse energy of 328 nJ is achieved at the pump power of 97.6 mW. Our results show that multi-layer BP is a promising SA for Q-switching laser operation.

关键词： of SA Q-Switched Ytterbium-Doped Fiber Laser Using Black Phosphorus as Saturable Absorber in is for BP that Figure khz mode

Optical and electrical characterizations of nanoparticle Cu_2S thin films

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Chinese Physics B 2014年第4期23卷 476-481页

作者： m.Saadeldin h.S.Soliman h.A.m.Ali K.Sawaby Physics Department Faculty of Science Cairo University Physics Department Faculty of Education Ain-Shams University

Copper sulfide thin films are deposited onto different substrates at room temperature using the thermal evaporation technique. X-ray diffraction spectra show that the film has an orthorhombicchalcocite （7-Cu2S） phase. The atomic force microscopy images indicate that the film exhibits nanoparticles with an average size of nearly 44 nm. Specrtophotometric measurements for the transmittance and reflectance are carried out at normal incidence in a spectral wavelength range of 450 nm-2500 nm. The refractive index, n, as well as the absorption index, k is calculated. Some dispersion parameters are determined. The analyses of el and e2 reveal several absorption peaks. The analysis of the spectral behavior of the absorption coefficient, c~, in the absorption region reveals direct and indirect allowed transitions. The dark electrical resistivity is studied as a function of film thickness and temperature. Tellier＇s model is adopted for determining the mean free path and bulk resistance.

关键词： physical properties of Cu2S thermal evaporation nanoparticle Cu2S thin films

On the Relationship between Climatic Variables and Pressure Systems over Saudi Arabia in the Winter Season

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Advances in Atmospheric Sciences 2015年第5期32卷 690-703页

作者： h.m.hASANEAN h.Abdel BASSET m.A.A.hUSSEIN Department of meteorology Faculty of Meteorology Environment and Arid Land AgricultureKing Abdulaziz University Department of meteorology and Astronomy Faculty of Science Al-Azhar University

The synoptic circulation over Saudi Arabia is complicated and frequently governed by the effect of large-scale pressure systems. In this work, we used NCEP–NCAR global data to illustrate the relationship between climatic variables and the main pressure systems that affect the weather and climate of Saudi Arabia, and also to investigate the influence of these pressure systems on surface air temperature（SAT） and rainfall over the region in the winter season. It was found that there are two primary patterns of pressure that influence the weather and climate of Saudi Arabia. The first occurs in cases of a strengthening Subtropical high（Sub h）, a weakening Siberian high（Sib h）, a deepening of the Icelandic Low（Ice L）, or a weakening of the Sudanese Low（Sud L）. During this pattern, the Sub h combines with the Sib h and an obvious increase of sea level pressure（SLP） occurs over southern European, the mediterranean, North Africa, and the middle East. This belt of high pressure prevents interaction between midlatitude and extratropical systems, which leads to a decrease in the SAT,relative humidity（Rh） and rainfall over Saudi Arabia. The second pattern occurs in association with a weakening of the Sub h, a strengthening of the Sib h, a weakening of the Ice L, or a deepening of the Sud L. The pattern arising in this case leads to an interaction between two different air masses： the first（cold moist） air mass is associated with the mediterranean depression travelling from west to east, while the second（warm moist） air mass is associated with the northward oscillation of the Sud L and its inverted V-shape trough. The interaction between these two air masses increases the SAT, Rh and the probability of rainfall over Saudi Arabia, especially over the northwest and northeast regions.

关键词： climatic variables pressure system surface air temperature rainfall relative humidity Saudi Arabia