Articles de revues : « 2S2P1D model »

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Yusoff, Md, N. I. Monieur D. et Airey G. D. « The 2S2P1D : An Excellent Linear Viscoelastic Model ». Journal of Civil Engineering, Science and Technology 1, n^o 2 (1 avril 2010) : 1–7. http://dx.doi.org/10.33736/jcest.76.2010.

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An experimental campaign has been carried out on five different unaged and five aged penetration grade bitumens to determine the properties of the 2S2P1D (combinations of two springs, two parabolic elements and one dashpot) model. The dynamic oscillatory test was conducted in order to obtain the rheological data using the dynamic shear rheometer (DSR). Earlier, the samples were aged following the Rolling Thin Film Oven Test (RTOFT) test procedure. It was found that the 2S2P1D model which consists of seven parameters simulates in an excellent way the linear viscoelastic properties of aged and unaged penetration grade bitumens over a wide range of temperatures and frequencies. The goodness of fit statistical analysis showed that the model had a good correlation and comparable to the measured dynamic data.

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Daoudi, Abdeldjalil, Daniel Perraton, Anne Dony et Alan Carter. « From Complex Modulus E* to Creep Compliance D(t) : Experimental and Modeling Study ». Materials 13, n^o 8 (21 avril 2020) : 1945. http://dx.doi.org/10.3390/ma13081945.

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Creep compliance (D(t)) is a very important input for the thermal cracking resistance in the Mechanistic-Empirical Pavement Design Guide (MEPDG). The aim of the work presented here is to predict the results of creep compliance D(t) from the result of complex modulus E*(ω). The work plan is divided in two main parts: an experimental part consisting of creep tests, and a modeling part. Three configurations were compared together, namely direct tensile, direct compression and indirect tensile tests. The modelling part consists of using a 2S2P1D model coupled to Kopelman approximation to switch from the frequency domain to the time domain. Additionally, 2S2P1D was used to calibrate the generalized Kelvin–Voigt model and get the creep compliance directly from E* results. The experimental results show that D(t) from direct tensile and direct compression are the same in the viscoelastic domain and are greater than D(t) from the indirect tensile test. The indirect tensile test (IDT) seems to be very difficult to achieve compared to the other two variants. The converted results using the 2S2P1D model coupled to Kopelman approximation and the results from the GKV model describe the experimental points very well.

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Zhang, Yan, et Yiren Sun. « Fast-Acquiring High-Quality Prony Series Parameters of Asphalt Concrete through Viscoelastic Continuous Spectral Models ». Materials 15, n^o 3 (18 janvier 2022) : 716. http://dx.doi.org/10.3390/ma15030716.

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Prony series representations have been extensively applied to characterizing the time-domain linear viscoelastic (LVE) material functions for asphalt concrete. However, existing methods that can generate high-quality Prony series parameters (i.e., discrete spectra) mostly involve complicated programming algorithms, which poses a challenge for quick access of Prony series parameters. Also, very limited research has been devoted to establishing methods for simultaneously determining both retardation and relaxation spectra. To resolve these issues, this study presented a practical approach to fast acquiring high-quality Prony series parameters for both relaxation modulus and creep compliance of asphalt concrete by using the complex modulus test data. The approach adopts the analytical representations of the continuous relaxation and retardation spectra from the Havriliak-Negami (HN) and 2S2P1D complex modulus models to directly determine the discrete spectra, and the elastic constants, Ee and Dg, for both LVE modulus and compliance functions are further calculated by fitting the corresponding generalized Maxwell model representations to smoothed data from the storage modulus representations of the HN and 2S2P1D complex modulus models. In this way, all the procedures in the proposed method can be easily implemented in Microsoft Excel. The results showed that the HN and 2S2P1D models yielded slightly different continuous spectral patterns at shorter relaxation times and longer retardation times. However, at the region covered by the test data, the continuous spectra of the two complex modulus models were very close to each other. Thus, the two models can generate comparable Prony series parameters within the time or frequency range covered by the test data. Considering that the quality of the resulting Prony series parameters are closely related to the master curve models used for presmoothing, the HN and 2S2P1D models were compared with the conventional Sigmoidal model. Additionally, the Black diagram was recommended for examining the quality of the complex modulus test data before constructing the master curves.

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Ma, Xiaoyan, Xingyu Zhang, Junpeng Hou, Shanglin Song, Huaxin Chen et Dongliang Kuang. « Predicting Dynamic Properties of Asphalt Mastic Considering Asphalt–Filler Interaction Based on 2S2P1D Model ». Materials 15, n^o 16 (18 août 2022) : 5688. http://dx.doi.org/10.3390/ma15165688.

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The relationship between the various phases of asphalt materials, from asphalt binder to mastic and mixture, has received great attention over the years, with efforts being made to establish linkages among these phases. Many methods for predicting the rheology properties of asphalt mastics from those of asphalt and filler volume fractions exist. However, most prediction methods are based on an empirical formula and on the micromechanical model. Very few research studies focus on the constitutive model. In addition, relatively little research has explored the influence of asphalt–filler interaction on mastic’s rheology properties, which is believed to be an important factor. In this study, the 2S2P1D (two springs, two parabolic elements, and one dashpot) model was applied to link the behavior of asphalt binder, filler volume fraction, asphalt–filler interaction and asphalt mastic. First, the interaction between asphalt and filler was evaluated, and the interaction parameter C of the Palierne model was used as an assessment indicator to calculate the effective filler volume fraction of asphalt mastic. Then, the relation between the 2S2P1D model parameters of asphalt mastic and those of asphalt binder and the effective filler volume fraction was analyzed. Finally, a simple relationship associating the 2S2P1D model parameters h, log(τ0) of mastic and that of asphalt binder and the effective filler volume fraction was developed. The proposed expression was validated, and the result showed that it was an efficient model for the shear complex modulus prediction of virgin asphalt mastic.

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Mangiafico, S., C. Sauzéat et H. Di Benedetto. « 2S2P1D Model Calibration Error from User Panel for One Bitumen and One Bituminous Mixture ». Advances in Materials Science and Engineering 2019 (26 mai 2019) : 1–16. http://dx.doi.org/10.1155/2019/6547025.

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The objective of this study is to analyse the differences between experimental LVE properties of both a straight-run bitumen and a bituminous mixture and simulations with analogical 2S2P1D (2 Springs, 2 Parabolic elements, and 1 Dashpot) model fitted by 14 different users. Data for the bitumen consisted of isotherms of G∗ and φ obtained from DSR complex modulus tests at 12 different temperatures ranging from −29.9°C to 60.0°C and frequencies ranging from 6.3 to 40 Hz, for a total of 60 data points. Data for the bituminous mixture consisted of isotherms of E∗ and φ obtained from strain-controlled traction/compression complex modulus tests at 8 different temperatures ranging from −29.7°C to 38.8°C and frequencies ranging from 0.01 to 10 Hz, for a total of 55 data points. All users worked independently and for the same time duration of one hour to fit the 2S2P1D model on both sets of data. Successful simulations of experimental data of both bitumen and mixture were generally obtained by all the users over the whole range of frequencies and temperatures, regardless of their familiarity and experience with the model. The accuracy of the model to fit experimental data is all the more evident if the great spans of complex modulus (G∗ of the bitumen between 10−2 and 103 MPa, E∗ of the mixture between 10 and 40000 MPa) are considered. The obtained results highlight the convenience of 2S2P1D model to perform multiscale modelling of LVE behaviour of bituminous materials, from bitumens to mixtures.

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Yang, Shengfeng, Kezhen Yan et Wenyao Liu. « The Effect of Ultraviolet Aging Duration on the Rheological Properties of Sasobit/SBS/Nano-TiO2-Modified Asphalt Binder ». Applied Sciences 12, n^o 20 (20 octobre 2022) : 10600. http://dx.doi.org/10.3390/app122010600.

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In recent years, nanoparticles have been introduced into warm-mix-modified asphalt to improve asphalt performance after sustaining ultraviolet (UV) aging, yet the evaluation of aging performance is often a descriptive characterization of rheological properties. This study extends rheological characterization with viscoelastic mechanical modeling to evaluate resistance to UV aging using Sasobit and SBS compound-modified binder blended with nano-titanium dioxide (TiO2). The extended method comprises characterizations using several rheological properties and a viscoelastic mechanical model, named the 2S2P1D model, on modified asphalt after 3 days, 6 days and 9 days of ultraviolet (UV) aging. The rheological properties of the UV-aged binders were tested at high and medium temperatures in terms of viscosity, complex modulus, phase angle and fatigue factor. Rheological test results showed that nanoparticles generally had no apparent effect on the complex modulus of aged binders regardless of UV aging times. However, the aged binder with nanoparticles showed better fatigue resistance than aged binders without nanoparticles after 3 days of UV aging. As an extension, the black space diagram and 2S2P1D model were used to investigate the viscoelastic properties of these aged binders. The k and h values, as important model parameters, were almost the same and less than one for all UV-aged binders. All investigated aged asphalt binders showed characteristics of a viscoelastic solid in terms of the master curves of the complex modulus and phase angle, and the master curves of the phase angle for all UV-aged binders did not meet the time–temperature equivalence. Moreover, these observations from the 2S2P1D model revealed that aging durations did not affect the viscoelastic mechanical characteristics of warm mix asphalt in this study. The method adopted in this study may promote a comprehensive evaluation of asphalt properties after UV aging, especially considering the viscoelastic mechanical performance.

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Md. Yusoff, Nur Izzi, Damien Mounier, Ginoux Marc-Stéphane, Mohd Rosli Hainin, Gordon D. Airey et Hervé Di Benedetto. « Modelling the rheological properties of bituminous binders using the 2S2P1D Model ». Construction and Building Materials 38 (janvier 2013) : 395–406. http://dx.doi.org/10.1016/j.conbuildmat.2012.08.038.

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Tuan, Nguyen Quang. « Mechanical properties of bituminous mixtures under sinusoidal cyclic loadings : Experiment and modelling ». Journal of Science and Technology in Civil Engineering (STCE) - NUCE 15, n^o 2 (27 avril 2021) : 67–76. http://dx.doi.org/10.31814/stce.nuce2021-15(2)-06.

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Mechanical behaviour of bituminous mixtures is characterized by the great thermal sensitivity and the large viscous effects. This paper focuses on the linear viscoelastic (LVE) behaviour of bituminous mixtures that is considered for pavement design. The studied material is a GB3 mix (GB in French is “Grave Bitume”) which is often used for base course construction in France. Complex modulus tests are performed to determine the LVE properties of bituminous mix. Sinusoidal cyclic loadings in tension and compression for small strain amplitudes (up to 10-4 m/m) are applied on cylindrical samples at different temperatures (from -23.4°C to 39.1°C) and different frequencies (from 0.03 to 10Hz). The complex modulus E* and complex Poisson’s ratio ν* are obtained for these large ranges of temperature and frequency. From all these data, it is shown that within the linear viscoelastic domain and in the 3D case, the Time Temperature Superposition Principle (TTSP) is applicable and verified. A model with a continuum spectrum called 2S2P1D (2S2P1D means two Springs, two Parabolic elements, one Dashpot), developed at the Ecole Nationale des Travaux Publics de l’Etat (ENTPE), is used to simulate the 3D LVE behaviour of tested bituminous mixture. Keywords: linear viscoelasticity; bituminous mixture; modelling; complex modulus; complex Poisson’s ratio.

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Carret, Jean-Claude, Hervé Di Benedetto et Cédric Sauzéat. « Characterization of Asphalt Mixes Behaviour from Dynamic Tests and Comparison with Conventional Cyclic Tension–Compression Tests ». Applied Sciences 8, n^o 11 (1 novembre 2018) : 2117. http://dx.doi.org/10.3390/app8112117.

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In the presented research, conventional cyclic tension–compression tests and dynamic tests were performed on two types of asphalt mixes (AM). For the tension–compression tests, the complex modulus was obtained from the measurements of the axial stress and axial strain. For the dynamic tests, an automated impact hammer equipped with a load cell and an accelerometer were used to obtain the frequency response functions (FRFs) of the specimens at different temperatures. Two methods were proposed to back-calculate the complex modulus from the FRFs at each temperature: one using the 2S2P1D (two springs, two parabolic elements and one dashpot) model and the other considering a constant complex modulus. Then, a 2S2P1D linear viscoelastic model was calibrated to simulate the global linear viscoelastic behaviour back calculated from each of the proposed methods of analysis for the dynamic tests, and obtained from the tension–compression test results. The two methods of analysis of dynamic tests gave similar results. Calibrations from the tension–compression and dynamic tests also show an overall good agreement. However, the dynamic tests back analysis gave a slightly higher value of the norm of the complex modulus and a lower value of the phase angle compared to the tension–compression test data. This result may be explained by the nonlinearity of AM (strain amplitude is at least 100 times smaller for dynamic tests) and/or by ageing of the materials during the period between the tension–compression and the dynamic tests.

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Gu, Linhao, Luchuan Chen, Weiguang Zhang, Haixia Ma et Tao Ma. « Mesostructural Modeling of Dynamic Modulus and Phase Angle Master Curves of Rubber Modified Asphalt Mixture ». Materials 12, n^o 10 (22 mai 2019) : 1667. http://dx.doi.org/10.3390/ma12101667.

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The main objective of this paper was to develop a mesostructure-based finite element model of rubber modified asphalt mixture to predict both the dynamic modulus master curve and phase angle master curve under a large frequency range. The asphalt mixture is considered as a three-phase material consisting of aggregate, asphalt mortar, and air void. The mesostructure of the asphalt mixture was digitized by a computed tomography (CT) scan and implemented into finite element software. The 2S2P1D model was used to obtain the viscoelastic information of an asphalt mortar under a large range of frequencies and temperatures. The continuous spectrum of the 2S2P1D model was converted to a discrete spectrum and characterized by the generalized Maxwell model for numerical simulation. The Prony series parameters of the generalized Maxwell model and the elastic modulus of the aggregates were inputted into the finite element analysis as material properties. The dynamic modulus tests of a rubber modified asphalt mortar and asphalt mixture were conducted under different temperatures and loading frequencies. The dynamic modulus master curve and phase angle master curve of both asphalt mortar and asphalt mixture were constructed. The frequency of the finite element simulations of the dynamic modulus tests ranged from 10−6 to 104. The dynamic modulus and phase angle of the asphalt mixture was calculated and the master curves were compared with the master curves obtained from the experimental data. Furthermore, the effect of the elastic modulus of aggregates on the master curves was analyzed. Acceptable agreement between dynamic modulus master curves obtained from experimental data and simulation results was achieved. However, large errors between phase angle master curves appeared at low frequencies. A method was proposed to improve the prediction of the phase angle master curve by adjusting the equilibrium modulus of the asphalt mortar.

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Cao, Wei, Andrew Lacroix et Y. Richard Kim. « A triaxial linear viscoelastic characterization framework for asphalt concrete based on the 2S2P1D model ». European Journal of Mechanics - A/Solids 92 (mars 2022) : 104469. http://dx.doi.org/10.1016/j.euromechsol.2021.104469.

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Han, Ding, Chaochao Zhu, Qingcan Du et Huimin Hu. « Establishment and verification of different fixed parameter combinations of the 2S2P1D model for asphalt mixture ». Construction and Building Materials 345 (août 2022) : 128379. http://dx.doi.org/10.1016/j.conbuildmat.2022.128379.

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Olard, François, et Hervé di Benedetto. « General 2S2P1D Model and Relation Between the Linear Viscoelastic Behaviours of Bituminous Binders and Mixes ». Road Materials and Pavement Design 4, n^o 2 (30 juin 2003) : 185–224. http://dx.doi.org/10.3166/rmpd.4.185-224.

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Olard, François, et Hervé Di Benedetto. « General “2S2P1D” Model and Relation Between the Linear Viscoelastic Behaviours of Bituminous Binders and Mixes ». Road Materials and Pavement Design 4, n^o 2 (janvier 2003) : 185–224. http://dx.doi.org/10.1080/14680629.2003.9689946.

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Brondani, Chaveli, Pablo Menezes Vestena, Cléber Faccin, Silvio Lisboa Schuster, Luciano Pivoto Specht et Deividi da Silva Pereira. « Moisture susceptibility of asphalt mixtures : 2S2P1D rheological model approach and new index based on dynamic modulus master curve changes ». Construction and Building Materials 331 (mai 2022) : 127316. http://dx.doi.org/10.1016/j.conbuildmat.2022.127316.

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Iwański, Marek, Anna Chomicz-Kowalska, Grzegorz Mazurek, Przemysław Buczyński, Małgorzata Cholewińska, Mateusz M. Iwański, Krzysztof Maciejewski et Piotr Ramiączek. « Effects of the Water-Based Foaming Process on the Basic and Rheological Properties of Bitumen 70/100 ». Materials 14, n^o 11 (25 mai 2021) : 2803. http://dx.doi.org/10.3390/ma14112803.

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The process of water-based foaming of bitumen produces binders that can be incorporated in cold recycled asphalt mixes and pavement upper structural layers made of half-warm mix asphalt prepared at 100–130 °C. During the foaming process, cold water and air act on hot bitumen (160–170 °C), which results in the explosive vaporization of water leading to changes in the binder structure. The impact of foaming on the properties of bitumen 70/100 was evaluated by investigating the binder characteristics before and after foaming. Determination of two foaming parameters, maximum expansion and half-life, was followed by measurements of penetration at 25 °C, softening point, Fraass breaking point, and dynamic viscosity at 60, 90, and 135 °C. Rheological and low-temperature tests were also performed before and after foaming bitumen 70/100. The Bending Beam Rheometer method was applied to determine the low temperature stiffness modulus. A DHR-2 rheometer was used to determine the dynamic modulus and phase angle of the tested binder. The Black and master curves before and after foaming were plotted in the 2S2P1D model and the model parameters were analysed. Analysis of the test results confirmed the effects of the foaming process on the basic, low-temperature, and rheological characteristics of the bitumen.

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Wang, Di, Augusto Cannone Falchetto, Alexander Alisov, Johannes Schrader, Chiara Riccardi et Michael P. Wistuba. « An Alternative Experimental Method for Measuring the Low Temperature Rheological Properties of Asphalt Binder by Using 4mm Parallel Plates on Dynamic Shear Rheometer ». Transportation Research Record : Journal of the Transportation Research Board 2673, n^o 3 (mars 2019) : 427–38. http://dx.doi.org/10.1177/0361198119834912.

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The possibility of using the dynamic shear rheometer (DSR) with 4 mm parallel plates and 3 mm gap is investigated as an alternative experimental method to measure the rheological properties of asphalt binders at low temperature. A special butterfly silicone mold was prepared for this purpose and the corresponding testing procedure was also developed. Five different asphalt binders, which are part of two active research projects, were selected. Frequency and temperature sweep tests were conducted using the DSR with three plate–plate geometries: 4 mm, 8 mm, and 25 mm. The new testing procedure was used to measure at low temperatures. The method recently proposed by the Western Research Institute and based on DSR tests with 4 mm parallel plates and 1.75 mm gap was also used for comparison purposes. Black diagrams and Cole-Cole plots were then used to evaluate the experimental data. Complex modulus and phase angle master curves were generated, and the rheological parameters compared. Finally, the two spring, two parabolic elements, one dashpot (2S2P1D) model was selected to investigate the rheological properties of the binders. Results indicate that the proposed procedure is a simple and reliable experimental method and represents an alternative experimental option to measure and analyze the rheological properties of asphalt binders at low temperature.

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Aufleger, Lennart, Patrick Friebel, Patrick Rupprecht, Alexander Magunia, Thomas Ding, Marc Rebholz, Maximilian Hartmann, Christian Ott et Thomas Pfeifer. « Line-shape broadening of an autoionizing state in helium at high XUV intensity ». New Journal of Physics 24, n^o 1 (1 janvier 2022) : 013014. http://dx.doi.org/10.1088/1367-2630/ac3b2e.

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Abstract We study the interaction of intense extreme ultraviolet (XUV) light with the 2s2p doubly excited state in helium. In addition to previously understood energy-level and phase shifts, high XUV intensities may lead to other absorption-line-shape distortions. Here, we report on experimental transient-absorption spectroscopy results on the 2s2p line-width modification in helium in intense stochastic XUV fields. A few-level-model simulation is realized to investigate the origins of this effect. We find that the line-shape broadening is connected to the strong coupling of the ground state to the 2s2p doubly excited state which is embedded in the ionization continuum. As the broadening takes place for intensities lower than for other strong-coupling processes, e.g. observed asymmetry changes of the absorption profile, this signature can be identified already in an intermediate intensity regime. These findings are in general relevant for resonant inner-shell transitions in nonlinear experiments with XUV and x-ray photon energies at high intensity.

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Yıldız, Murat, et Yasin Gökçe. « Lifetimes for singly ionized nitrogen ». Canadian Journal of Physics 92, n^o 1 (janvier 2014) : 82–85. http://dx.doi.org/10.1139/cjp-2013-0355.

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The lifetimes of some excited levels for singly ionized nitrogen are calculated by using the weakest bound electron potential model theory and quantum defect orbital theory. We determined expectation values of radii using numerical nonrelativistic Hartree–Fock wave functions. The necessary energy values have been taken from NIST. The present results have been compared with previous calculations and experiments. Most of the lifetime results are presented for the first time in the present work. For N II, because there are few lifetime results available in the literature, the present study compared to existing investigations, provides detailed results for the lifetimes of several of the excited 2s22pns, 2s22pnp, and 2s22pd → 2s22p2 where, n = 3–6 for the ns series, n = 3–5 for the nd series and n = 3–4 for the np series.

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Jankowski, K., et P. Malinowski. « Application of the complete-model-space MR-CCSD theory to the 2s21S and 2p21S states of Be ». Chemical Physics Letters 205, n^o 4-5 (avril 1993) : 471–78. http://dx.doi.org/10.1016/0009-2614(93)87153-t.

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Magunia, Alexander, Lennart Aufleger, Thomas Ding, Patrick Rupprecht, Marc Rebholz, Christian Ott et Thomas Pfeifer. « Bound-State Electron Dynamics Driven by Near-Resonantly Detuned Intense and Ultrashort Pulsed XUV Fields ». Applied Sciences 10, n^o 18 (4 septembre 2020) : 6153. http://dx.doi.org/10.3390/app10186153.

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We report on numerical results revealing line-shape asymmetry changes of electronic transitions in atoms near-resonantly driven by intense extreme-ultraviolet (XUV) electric fields by monitoring their transient absorption spectrum after transmission through a moderately dense atomic medium. Our numerical model utilizes ultrashort broadband XUV laser pulses varied in their intensity (1014–1015 W/cm2) and detuning nearly out of resonance for a quantitative evaluation of the absorption line-shape asymmetry. It will be shown how transient energy shifts of the bound electronic states can be linked to these asymmetry changes in the case of an ultrashort XUV driving pulse temporally shorter than the lifetime of the resonant excitation, and how the asymmetry can be controlled by the near-resonant detuning of the XUV pulse. In the case of a two-level system, the numerical model is compared to an analytical calculation, which helps to uncover the underlying mechanism for the detuning- and intensity-induced line-shape modification and links it to the generalized Rabi frequency. To further apply the numerical model to recent experimental results of the near-resonant dressing of the 2s2p doubly excited state in helium by an ultrashort XUV free-electron laser pulse we extend the two-level model with an ionization continuum, thereby enabling the description of transmission-type (Fraunhofer-like) transient absorption of a strongly laser-coupled autoionizing state.

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Wang, Rui, Kan Wu, Qimin He, Yibo He, Yuanyuan Gu et Shuang Wu. « A Novel Method of Monitoring Surface Subsidence Law Based on Probability Integral Model Combined with Active and Passive Remote Sensing Data ». Remote Sensing 14, n^o 2 (10 janvier 2022) : 299. http://dx.doi.org/10.3390/rs14020299.

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For the accurate and high-precision measurement of the deformation field in mining areas using different data sources, the probability integral model was used to process deformation data obtained from an Unmanned Aerial Vehicle (UAV), Differential InSAR (DInSAR), and Small Baseline Subset InSAR (SBAS-InSAR) to obtain the complete deformation field. The SBAS-InSAR, DInSAR, and UAV can be used to obtain small-scale, mesoscale, and large-scale deformations, respectively. The three types of data were all superimposed by the Kriging interpolation, and the deformation field was integrated using the probability integral model to obtain the complete high-precision deformation field with complete time series in the study area. The study area was in the WangJiata mine in Western China, where mining was carried out from 12 July 2018 to 25 October 2018, on the 2S201 working face. The first observation was made in June 2018, and steady-state observations were made in April 2019, totaling four UAV observations. During this period, the Canadian Earth Observation Satellite of Radarsat-2 (R2) was used to take 10 SAR images, the surface subsidence mapping was undertaken using DInSAR and SBAS-InSAR techniques, and the complete deformation field of the working face during the 106-day mining period was obtained by using the UAV technique. The results showed that the subsidence basin gradually expanded along the mining direction as the working face advanced. When the mining advance was greater than 1.2–1.4 times the coal seam burial depth, the supercritical conditions were reached, and the maximum subsidence stabilized at the value of 2.780 m. The subsidence rate was basically maintained at 0.25 m/d. Finally, the accuracy of the method was tested by the Global Navigation Satellite System (GNSS) data, and the medium error of the strike was 0.103 m. A new method is reached by the fusion of active and passive remote sensing data to construct efficient, complete and high precision time-series subsidence basins with high precision.

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Cherukuri, Santhan Kumar, et Srinivasa Rao Rayapudi. « Enhanced Grey Wolf Optimizer based MPPT Algorithm of PV system under Partial Shaded Condition ». International Journal of Renewable Energy Development 6, n^o 3 (6 novembre 2017) : 203. http://dx.doi.org/10.14710/ijred.6.3.203-212.

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Partial shading condition is one of the adverse phenomena which effects the power output of photovoltaic (PV) systems due to inaccurate tracking of global maximum power point. Conventional Maximum Power Point Tracking (MPPT) techniques like Perturb and Observe, Incremental Conductance and Hill Climbing can track the maximum power point effectively under uniform shaded condition, but fails under partial shaded condition. An attractive solution under partial shaded condition is application of meta-heuristic algorithms to operate at global maximum power point. Hence in this paper, an Enhanced Grey Wolf Optimizer (EGWO) based maximum power point tracking algorithm is proposed to track the global maximum power point of PV system under partial shading condition. A Mathematical model of PV system is developed under partial shaded condition using single diode model and EGWO is applied to track global maximum power point. The proposed method is programmed in MATLAB environment and simulations are carried out on 4S and 2S2P PV configurations for dynamically changing shading patterns. The results of the proposed method are analyzed and compared with GWO and PSO algorithms. It is observed that proposed method is effective in tracking global maximum power point with more accuracy in less computation time compared to other methods.Article History: Received June 12nd 2017; Received in revised form August 13rd 2017; Accepted August 15th 2017; Available onlineHow to Cite This Article: Kumar, C.H.S and Rao, R.S. (2017 Enhanced Grey Wolf Optimizer Based MPPT Algorithm of PV System Under Partial Shaded Condition. Int. Journal of Renewable Energy Development, 6(3), 203-212.https://doi.org/10.14710/ijred.6.3.203-212

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Ramakrishna, K., et J. R. Trent. « Prediction of Thermal Performance of Wire-Bonded Plastic Ball Grid Array Package for Underhood Automotive Applications ». Journal of Electronic Packaging 125, n^o 3 (1 septembre 2003) : 447–55. http://dx.doi.org/10.1115/1.1602710.

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Thermal performance of a three chip, overmolded wire-bonded plastic ball grid array (WB-PBGA) package with four layer substrate attached to a 1.52-mm-thick, four-layer (2s2p), FR4 printed wiring board (PWB) has been evaluated under horizontal natural convection conditions for underhood automotive applications as a function of ambient temperature, package design parameters, and thermophysical properties of the package and PWB materials. A two-tier modeling approach, which accurately accounts for multidimensional heat transfer effects caused by substrate features such as vias and C5 solder joints, has been developed and implemented. In this methodology, the effect of small features is first characterized using a detailed micromodel from which an effective thermal conductivity is computed. The effective thermal conductivity is implemented in the global model thereby excluding the small features in the global model. The actual stackups of the package and PWB have been used in the computations to accurately determine the in-plane heat spreading. Using this methodology for automotive underhood applications, a parametric study of thermal performance of the WB-PBGA package has been carried out. This study shows that: 1. The maximum junction temperature rise above ambient, ΔT, decreases with increase in ambient temperature by 30% as the ambient temperature increases from 23 to 125°C. 2. ΔT decreases by 20% as the emissivity of the molding compound and the PWB surfaces increases from 0 (no radiative loss) to 0.8 under natural convection conditions. 3. The decrease in ΔT is small (∼7%) as the thermal conductivity of the die attach material varies over a wide range. 4. ΔT decreases by 30% as the thermal conductivity of the molding compound is varied over a wide range. 5. ΔT decreases by 45% as the thermal conductivity of the substrate increases (i.e., as the number of vias in the substrate increase) from no vias case to densely populated vias.

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Gourdon, E., C. Sauzéat, H. Di Benedetto et K. Bilodeau. « Seven-Parameter Linear Viscoelastic Model Applied to Acoustical Damping Materials ». Journal of Vibration and Acoustics 137, n^o 6 (1 décembre 2015). http://dx.doi.org/10.1115/1.4030719.

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In this paper, linear viscoelastic rheological properties of acoustical damping materials are predicted. A rheological model, based on a mechanical element approach, is presented. It consists of a combination of two springs, two parabolic elements, and one dashpot (2S2P1D). This model is applied to different acoustical damping materials. Its specificity comes from the fact that elements might be linked to structural and physical features. Parameters might be experimentally determined by tests. Application of the 2S2P1D linear viscoelastic model can adequately predict the behavior of acoustical damping materials with good accuracy. If the material verifies the time–temperature superposition principle (TTSP), the proposed model can predict the behavior on a wide frequency range, even with a small number of available data.

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Tai Nguyen, H. T., Duy-Liem Nguyen, Vu-Tu Tran et Mai-Lan Nguyen. « Finite element implementation of Huet-Sayegh and 2S2P1D models for analysis of asphalt pavement structures in time domain ». Road Materials and Pavement Design, 26 août 2020, 1–25. http://dx.doi.org/10.1080/14680629.2020.1809501.

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