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    Wyświetlanie 1-8 z 8
    Tytuł:
    Influence of uncertainty in aerodynamic performance on the dynamic response of a two stage gear system
    Autorzy:
    Tounsi, M.
    Beyaoui, M.
    Abboudi, K.
    Feki, N.
    Walha, L.
    Haddar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/281135.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    gearbox
    uncertainty
    power coefficient
    random parameter
    polynomial chaos
    Opis:
    In this paper, the nonlinear dynamic response in a wind turbine system is considered and the quantification of uncertainty effects on the variability of this nonlinear response is investigated. Under dynamic conditions, a lumped model with 12 degrees of freedom is proposed taking into account the uncertainty associated to the power coefficient of the input aerodynamic torque. The dynamic response of the two-stage spur gear system is obtained using ODE45 solver of Matlab. The Polynomial Chaos (PC) method is used to introduce the uncertainties on the proposed model. A comparison between the two dynamic responses given by the proposed lumped dynamic model takes into account the uncertainty. It is performed on the existed model without uncertainty. Thus, the efficiency and robustness of the proposed new methodology is evaluated.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2016, 54, 2; 601-612
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of camshaft eccentricity and follower backlash on the dynamic behaviour flexible cam mechanism
    Autorzy:
    Tounsi, M.
    Chaari, F.
    Abbes, M. S.
    Fakhfakh, A. T.
    Haddar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/329630.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
    Tematy:
    wał rozrządu
    charakterystyka dynamiczna
    symulacja
    cam
    follower
    dynamic response simulation
    camshaft eccentricity
    follower backlash
    Opis:
    A cam follower system is modelled in this work. The equation of motion and the eigenfrequencies are recovered. The computation of the dynamic response is made by mean of combined implicit Newmark-Newton Raphson algorithm. Moreover, dynamic behaviour of the follower train is analysed in presence of an eccentricity in the camshaft and backlash between the follower rods and its guide.
    Źródło:
    Diagnostyka; 2010, 2(54); 3-9
    1641-6414
    2449-5220
    Pojawia się w:
    Diagnostyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Phytochemical characterisation and bioactive properties of Solanum sodomaeum L. fruits at two stages of maturation
    Autorzy:
    Ouerghemmi, I.
    Farhat, M.B.
    Harbeoui, H.
    Hammami, M.
    Hamdaoui, G.
    Marzouk, B.
    Tounsi, M.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/71442.pdf
    Data publikacji:
    2018
    Wydawca:
    Instytut Włókien Naturalnych i Roślin Zielarskich
    Tematy:
    phytochemistry
    bioactive property
    antibacterial property
    antioxidant activity
    essential oil
    fatty acid
    Solanum sodomaeum
    fruit
    maturation
    Opis:
    Introduction: Solanum sodomaeum L. has been observed to have several medicinal properties, in particular, in the treatment of several types of human skin cancer. Objective: The influence of the maturation stage of S. sodomaeum fruits on the total lipid contents, fatty acid profiles, essential oil yields and compositions, as well as the antibacterial and antioxidant activities of the essential oils, was investigated. Methods: The fatty acid and essential oil constituents were identified using gas chromatography (GC) and GC–mass spectrometry (GC–MS). The antioxidant properties of essential oil and vegetal oil were assessed using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging and reducing power assays. The antibacterial ac-tivity of essential oil was tested using the disc diffusion assay for resistance in human pathogenic bacteria. Results: Mature fruits showed higher total lipid content (17%) and were characterised by polyunsaturated fatty acids (53.87%), represented mainly by linoleic acid (53.11%). Similar yields of essential oils were detected for immature (0.43%) and mature (0.45%) fruits. Tetrahydronaphthalene (41.79%) was detected as the major essential oil component at the immature stage versus dihydrocoumarin pentane (18.27%), hexadecanoic acid (17.43%) and 2-undecanone (13.20%) in mature fruits. The DPPH test showed that essential oils had better antioxidant properties; however, the vegetal oils showed better performance in the reducing power assay. Moreover, the essential oil of S. sodomaeum mature fruits was active against bacterial strains. Conclusions: S. sodomaeum fruits could be a valuable source of natural antioxidants and antibacterial agents.
    Źródło:
    Herba Polonica; 2018, 64, 3
    0018-0599
    Pojawia się w:
    Herba Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electroacoustic Analysis of a Controlled Damping Planar CMOS-MEMS Electrodynamic Microphone
    Autorzy:
    Tounsi, F.
    Mezghani, B.
    Rufer, L.
    Masmoudi, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/177602.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    MEMS sensor
    acoustical model
    monolithic electroacoustic microphone
    suspended diaphragm
    lumped element modeling
    Opis:
    This paper gives a detailed electroacoustic study of a new generation of monolithic CMOS micromachined electrodynamic microphone, made with standard CMOS technology. The monolithic integration of the mechanical sensor with the electronics using a standard CMOS process is respected in the design, which presents the advantage of being inexpensive while having satisfactory performance. The MEMS microphone structure consists mainly of two planar inductors which occupy separate regions on substrate. One inductor is fixed; the other can exercise out-off plane movement. Firstly, we detail the process flow, which is used to fabricate our monolithic microphone. Subsequently, using the analogy between the three different physical domains, a detailed electro-mechanical-acoustic analogical analysis has been performed in order to model both frequency response and sensitivity of the microphone. Finally, we show that the theoretical microphone sensitivity is maximal for a constant vertical position of the diaphragm relative to the substrate, which means the distance between the outer and the inner inductor. The pressure sensitivity, which is found to be of the order of a few tens of μV/Pa, is flat within a bandwidth from 50 Hz to 5 kHz.
    Źródło:
    Archives of Acoustics; 2015, 40, 4; 527-537
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Non-linear analysis of functionally graded plates in cylindrical bending based on a new refined shear deformation theory
    Nieliniowa analiza zginania walcowego płyt wykonanych z materiału gradientowego w oparciu o nową teorię odkształcenia postaciowego
    Autorzy:
    Derras, M.
    Kaci, A.
    Draiche, K.
    Tounsi, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/949179.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    functional composites
    plate
    large deformation
    energy method
    Opis:
    A new refined shear deformation theory for the nonlinear cylindrical bending behavior of functionally graded (FG) plates is developed in this paper. This new theory is based on the assumption that the transverse displacements consist of bending and shear components, in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments. The theory accounts for a quadratic variation of the transverse shear strains across the thickness, and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. The plates are subjected to pressure loading, and their geometric nonlinearity is introduced in the strain-displacement equations based on Von-Karman assumptions. The material properties of plate are assumed to vary according to the Power law distribution of the volume fraction of the constituents. The solutions are achieved by minimizing the total potential energy and the results are compared to the classical, the first-order and other higher-order theories reported in the literature. It can be concluded that the proposed theory is accurate and simple in solving the nonlinear cylindrical bendig behavior of functionally graded plates.
    W niniejszym artykule zaprezentowana została nowa, udoskonalona teoria odkształcenia postaciowego dla przypadku zginania walcowego płyt wykonanych z funkcjonalnie gradientowego (FG) materiału. Teorię tę oparto na założeniu, że przemieszczenie poprzeczne jest wynikiem efektu zginania i ścinania, ale zginanie nie wpływa na siły tnące ani ścinanie na wartość momentu gnącego. Teoria wprowadza potęgową zależność czwartego stopnia odkształceń postaciowych w funkcji grubości płyty i spełnia warunek brzegowy zerowania naprężeń ścinających na zewnętrznych powierzchniach płyty bez użycia współczynników korekcyjnych. W pracy zbadano płyty poddane ciągłym obciążeniom zewnętrznym, a uwzględniona nieliniowość miała charakter geometryczny wynikający z opisu związku von Karmana pomiędzy odkształceniem i przemieszczeniem. Gradientowe właściwości materiału ujęto potęgowym rozkładem poszczególnych składników wzdłuż grubości płyty. Rozwiązania otrzymano poprzez minimalizację całkowitej energii potencjalnej przy zginaniu, a uzyskane wyniki porównano ze znanymi w literaturze rezultatami klasycznej teorii odkształcenia pierwszego oraz wyższych rzędów. Przedstawiona analiza potwierdziła, że nowo zaproponowana teoria jest dokładna i prosta w rozwiązywaniu nieliniowego problemu zginania walcowego płyt wykonanych z materiałów gradientowych.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 339-348
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inverse method for a one-stage spur gear diagnosis
    Autorzy:
    Akrout, A.
    Tounsi, D.
    Taktak, M.
    Abbes, M. S.
    Haddar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/949292.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    Independent Component Analysis (ICA)
    source identification
    gear mechanism
    geometrical defects
    Opis:
    In this paper, a source separation approach based on the Blind Source Separation (BSS) is presented. In fact, the Independent Component Analysis (ICA), which is the main technique of BSS, consists in extracting different source signals from several observed mixtures. This inverse method is very useful in many fields such as telecommunication, signal processing and biomedicine. It is also very attractive for diagnosis of mechanical systems such as rotating machines. Generally, dynamic responses of a given mechanical system (displacements, accelerations and speeds) measured through sensors are used as inputs for the identification of internal defaults. In this study, the ICA concept is applied to the diagnosis of a one-stage gear mechanism in which two types of defects (the eccentricity error and the localized tooth defect)are introduced. The finite element method allows determination of the signals corresponding to the acceleration in some locations of the system, and those signals may be used also in the ICA algorithm. Hence, the vibratory signatures of each defect can be identified by the ICA concept. Thus, a good agreement is obtained by comparing the expected default signatures to those achieved by the developed inverse method.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2015, 53, 3; 617-628
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Vibro-acoustic analysis of laminated double glazing using the force identification method
    Autorzy:
    Ben Jdidia, M
    Akrout, A
    Tounsi, D
    Fakhfakh, T.
    Haddar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/949211.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    fluid-structure interaction
    thin-film laminated plate
    ICA
    excitation force
    Kurtosis
    Opis:
    This paper presents a procedure for identifying wave forms and excitation frequencies of some forces applied on a given complex fluid-structure coupled system by using only its vibro-acoustic response. The considered concept is called the Independent Component Analysis (ICA) which is based on the Blind Source Separation (BSS). In this work, the ICA method is exploited in order to determine the excitation force applied to a thin-film laminated double glazing system enclosing a thin fluid cavity and limited by an elastic joint. The dynamic response of the studied fluid-structure coupled system is determined by finite element discretization and minimization of the homogenized energy functional of the coupled problem. This response will serve as the input for the ICA algorithm in order to extract the applied excitation.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2014, 52, 4; 895-904
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Distributed electrothermal modeling methodology for MOS gated power devices simulations
    Autorzy:
    Marcault, E
    Tounsi, P.
    Massol, J.-L
    Dorkel, J.-M
    Powiązania:
    https://bibliotekanauki.pl/articles/398045.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
    Tematy:
    electrothermal simulations
    reliability
    3D FEM simulation
    symulacje elektrotermiczne
    niezawodność
    symulacja metodą elementów skończonych 3D
    Opis:
    Currently electro-thermal simulations performed with 3D FEM simulators like ANSYS or COMSOL Multiphysics are limited to an imposed current flow through resistive materials. However, in the case of power MOS gated transistors like VDMOS transistors or IGBT, the channel resistance evolves with the gate voltage. This phenomenon is usually neglected in ON-state applications but seems to be determinant in switching application. Furthermore all the MOS cells of the transistors are not at the same temperature. This paper deals with a methodology that could allow taking into account the impact of the gate control and the MOS cells current distribution during 3D FEM electro-thermal simulations.
    Źródło:
    International Journal of Microelectronics and Computer Science; 2013, 4, 4; 148-152
    2080-8755
    2353-9607
    Pojawia się w:
    International Journal of Microelectronics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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