المؤلفون: Jamal Eddine, Abdul Karim, Lenti, Luca, Semblat, Jean François

المساهمون: Séismes et Vibrations (IFSTTAR/GERS/SV), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Communauté Université Paris-Est

المصدر: EVACES 2017, 7ht International Conference on Experimental Vibration Analysis for Civil Structures ; https://hal.science/hal-03233576Test ; EVACES 2017, 7ht International Conference on Experimental Vibration Analysis for Civil Structures, Jul 2017, San Diego, United States. pp 851-859, ⟨10.1007/978-3-319-67443-8_76⟩

مصطلحات موضوعية: VIBRATION, AMPLIFICATION, GRADIENT, WAVE PROPAGATION, PREDICTION EQUATION, SISMIQUE, PROPAGATION DES ONDES, PREVISION, CALCUL, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]

جغرافية الموضوع: San Diego, United States

الوصف: EVACES 2017, 7ht International Conference on Experimental Vibration Analysis for Civil Structures, San Diego, ETATS-UNIS, 12-/07/2017 - 14/07/2017 ; Wave propagation in soil is controlled by both attenuation and amplification laws. The former is due to geometrical and material damping, while the latter is mainly due to velocity contrasts between the various layers and possibly some geometrical/topographic effects. In the field of seismology and earthquake engineering, several factors are considered to describe the site properties and predict the amplifications features, such as average velocity \( V_{s30} \) and velocity-gradient-based coefficients. The reliability of these factors is questioned in the case of vibration problems, for which surface sources generated frequency components are much higher than in earthquake engineering. With this aim, considering various sites typologies, this paper suggests a set of relevant parameters for predicting vibration away from the vibratory source. Starting from numerical results (FEM), correlations between the proposed factors and the estimated displacements are discussed. These simple prediction equations are shown to be relevant and robust.

العلاقة: hal-03233576; https://hal.science/hal-03233576Test; https://hal.science/hal-03233576/documentTest; https://hal.science/hal-03233576/file/doc00032815.pdfTest

الإتاحة: https://doi.org/10.1007/978-3-319-67443-8_76Test
https://hal.science/hal-03233576Test
https://hal.science/hal-03233576/documentTest
https://hal.science/hal-03233576/file/doc00032815.pdfTest

المؤلفون: Gambarotta L., Bacigalupo A., Lepidi M.

المساهمون: Luigi Gambarotta, Andrea Bacigalupo, Marco Lepidi, G. Rega, Gambarotta, L., Bacigalupo, A., Lepidi, M.

مصطلحات موضوعية: Auxeticity, Blocky materials, Continualization, Lattices, Metamaterials, Optimal design, Wave propagation

الوصف: New avant-garde architected materials endowed with extreme stiffness, strength and lightness may be conceived through appropriate choices of the microstructural topology, mostly aimed at optimizing the periodic distribution between the solid phases and the voids. Moreover, microstructure topologies may be designed to maximize exotic mechanical properties, such as auxeticity and chirality. The tailored design of these materials is also fueled by the recent extraordinary developments in the technological fields of high-precision micro-engineering and high-fidelity additive manufacturing. Several periodic architected materials, namely lattice-like materials and rigid blocky materials, may be accurately modeled through discrete Lagrangian systems. The periodicity of the microstructure determines considerable scale effects, implying boundary layer effects and dispersive propagation of elastic waves. The need to derive synthetic descriptions of the mechanical properties and to reduce the computational burdens may motivate the formulation of non-conventional non-local homogenization techniques able of accurately describing the static and dynamic response of these materials. Within this challenging research area, the present Chapter synthesizes the most recent theoretical contributions by the Authors to the mechanical modelling of architected materials with periodic microstructure, with a methodological focus on enhanced non-local homogenization schemes, as well as on innovative surrogate optimization techniques for the spectral design of a new generation of metafilters.

وصف الملف: ELETTRONICO

العلاقة: info:eu-repo/semantics/altIdentifier/isbn/978-3-030-94194-9; info:eu-repo/semantics/altIdentifier/isbn/978-3-030-94195-6; ispartofbook:50+ Years of AIMETA: A Journey Through Theoretical and Applied Mechanics in Italy; firstpage:399; lastpage:417; numberofpages:19; alleditors:G. Rega; https://hdl.handle.net/11567/1151037Test; info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85160351357

الإتاحة: https://doi.org/10.1007/978-3-030-94195-6_25Test
https://hdl.handle.net/11567/1151037Test

المؤلفون: T. Stewart McKechnie

المصدر: Progress in Optical Science and Photonics ISBN: 9783030988272
Springer Series in Optical Sciences ISBN: 9783319182087

مصطلحات موضوعية: Physics, Wavelength, Ground wave propagation, Plane (geometry), Scattering, Wave propagation, Quantum mechanics, Correlation function (quantum field theory), Space (mathematics), Lambda

الوصف: This chapter deals with the propagation behavior of infinitely extensive plane light waves after passing through, and being scattered by a (hypothetical) thin inhomogeneous atmospheric layer. The propagation behavior is examined in the near-field Fresnel space beyond the layer which, at this preliminary stage, we consider homogeneous free space. The behavior of the crucially important, two-point two-wavelength correlation function of the complex amplitudes, \(S(x^{'} , y^{'} , x , y ,\lambda^{'} , \lambda )\), is examined as the waves propagate beyond the layer. The insights and results obtained in this chapter provide a foundation for the analysis given in the next chapter, which deals with wave propagation over extended atmospheric paths. When the two wavelengths coalesce, function 0\(S(x^{'} , y^{'} , x , y ,\lambda^{'} , \lambda )\) degenerates into the atmospheric MTF, \(S(x^{'} , y^{'} , x , y , \lambda )\). For any atmospheric path, the latter function determines the resolution that can be obtained when observing over that path. The development of scintillation is examined in the space below the layer; the extent to which it occurs depends crucially on the size of the turbulence structures in the layer.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c98b9994522565ec01cece55deee201eTest
https://doi.org/10.1007/978-3-030-98828-9_5Test

المؤلفون: T. Stewart McKechnie

المصدر: Progress in Optical Science and Photonics ISBN: 9783030988272
Springer Series in Optical Sciences ISBN: 9783319182087

مصطلحات موضوعية: Physics, Amplitude, Field (physics), Ground wave propagation, Correlation function, Wave propagation, Scattering, Autocorrelation, Plane wave, Computational physics

الوصف: This chapter examines the behavior of infinitely extensive plane waves as they propagate over extended atmospheric paths. The analysis draws on results from the previous chapter for scattering by thin atmospheric layers. Using a coherency matrix approach for the refractive index field, the crucial result is established that extended atmospheric paths can be represented by finite stacks of statistically independent random phase screens. By analytically propagating light waves through these stacks, expressions are developed for the atmospheric MTF and the two-point two-wavelength correlation function of the complex amplitudes of the waves that emerge from the stacks. The expressions are given in terms of the rms OPD fluctuation over the path, σ, and the autocorrelation function of that fluctuation, \(\rho (\xi ,\eta )\). These two measures provide the essential statistical information about turbulence structure in the path. They also provide the essential statistical properties of the complex amplitudes and intensities in images formed by telescopes observing over the path.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::734062417844bb037c42e6301c595897Test
https://doi.org/10.1007/978-3-030-98828-9_6Test

المؤلفون: Sergey I. Fomenko, Natalia Glushkova, Evgeny Glushkov

المصدر: Advanced Materials Modelling for Mechanical, Medical and Biological Applications ISBN: 9783030817046
Advanced Materials Modelling for Mechanical, Medical and Biological Applications

مصطلحات موضوعية: Materials science, Surface wave propagation, Mechanics

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::4c2ac6592d0e2bf49a58235a4ea2bb9fTest
https://doi.org/10.1007/978-3-030-81705-3_10Test

المؤلفون: Johann Vinkeloe, Neda Djordjevic, Lisa Zander

المصدر: Notes on Numerical Fluid Mechanics and Multidisciplinary Design ISBN: 9783030907266

مصطلحات موضوعية: Materials science, Wave propagation, Detonation, Hot spot (veterinary medicine), Mechanics, Combustion, Methane, law.invention, Ignition system, chemistry.chemical_compound, chemistry, Physics::Plasma Physics, law, Speed of sound, Physics::Chemical Physics, Shock tube

الوصف: Shockless Explosion Combustion is a novel combustion concept that achieves pressure gain combustion by quasi-homogeneous auto-ignition of the fuel/air mixture. Shockless Explosion Combustion is, like other combustion concepts based on auto-ignition, prone to premature ignition and detonation formation in the presence of reactivity gradients, so called hot spots. Two measures to inhibit detonation formation and to achieve quasi-homogeneous auto-ignition, dilution and fuel blending, are investigated by means of zero-dimensional simulations of generic hot spots. Experimental ignition delay times measured in a high pressure shock tube are used to select suitable chemical-kinetic models for the numerical investigation and the calculation of temperature sensitivities of ignition delay times. The main focus of this investigation are the two non-dimensional regime parameters \(\xi \) and \(\varepsilon \), as they enable characterization of the mode of auto-ignitive wave propagation from hot spots. \(\xi \) is the ratio between the speed of sound and the auto-ignitive wave propagation velocity and \(\varepsilon \) describes the ratio between the time a pressure wave travels through the hot spot and the excitation time. Dilution of the combustion mixture with steam and CO\(_2\) aims at extending excitation times and therefore decreasing the parameter \(\varepsilon \). Fuel blending of Dimethyl ether with hydrogen or methane aims at reducing the temperature sensitivity of ignition delay time and low values of \(\xi \). It is demonstrated that both measures are effective at mitigating detonation development while maintaining quasi-homogeneous auto-ignition in presence of hot spots.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::817e99ddea15c6eb27eaba59393ff1efTest
https://doi.org/10.1007/978-3-030-90727-3_2Test

المؤلفون: Zhang Zicheng, Kuo-Chi Chang, Ji Wei, Liang Quan, Zhu Xin, Yu Wenjie, Feng Zhihui

المصدر: Proceedings of the International Conference on Advanced Intelligent Systems and Informatics 2021 ISBN: 9783030897000

مصطلحات موضوعية: business.industry, Computer science, Iterative learning control, Tracking system, Tracking (particle physics), Interference (wave propagation), Convergence (routing), Trajectory, MATLAB, business, computer, Algorithm, Robotic arm, computer.programming_language

الوصف: For a class of two-degree-of-freedom robotic arm systems with strong coupling, time-varying parameters, and uncertain interference properties, the ILC algorithm has a fairly good control effect. In this paper, a multi-exponential accelerated ILC algorithm is proposed. Its convergence is analyzed; the algorithm mainly solves robotic arm trajectory tracking accuracy and iterative learning speed, which can realize fast and accurate tracking of robotic arm trajectory. Finally, the robot arm trajectory tracking system is simulated by MATLAB. The simulation results show that the improved algorithm effectively reduces the learning error and time compared with the original algorithm, which verifies the algorithm’s effectiveness.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::fc87b1a425ad8b363cd2ee28a1051bb4Test
https://doi.org/10.1007/978-3-030-89701-7_19Test

المؤلفون: Lyudmila Frishter

المصدر: Lecture Notes in Civil Engineering ISBN: 9783030799823

مصطلحات موضوعية: Stress (mechanics), Surface (mathematics), Photoelasticity, Extrapolation, Boundary (topology), Development (differential geometry), Geometry, Boundary value problem, Interference (wave propagation), Geology

الوصف: Assembled structures are distinguished in junction areas of elements of materials with different mechanical properties, under impacts of forced deformations, breaking along the contact line (surface) of the elements, by stress–strain state (SSS). A study of SSS in areas with wedge-shape boundary notches, of the junction of structural elements under impact of forced breaking deformations is a vital practical problem of the engineering design. The stress–strain state in boundary wedge-shape notch areas is obtained experimentally on photoelasticity method models and distinguished by significant stress gradients. In experiments, the interference stripes pattern in such areas is poorly legible. Theoretical studies of SSS in irregular boundary point area are generally reduced to solving of the singular uniform elastic boundary value problem. The complexity of the SSS in irregular boundary point area determines the demand for a complex approach to the study, including experimental data extrapolation method development and solution assessment of the boundary value in the irregular boundary point area. It is the purpose of the study described herein to evaluate the solution of the uniform elastic boundary value problem in the tip area of a wedge-shape notch of the boundary. The area, in which the solution assessment of the elastic value problem is given, is determined by photoelasticity method model.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::313c39ae2cb215ffda727b2ec15154adTest
https://doi.org/10.1007/978-3-030-79983-0_17Test

المؤلفون: Peter Kraemer, Jochen Moll, Jonas Brettschneider, Pawel Kudela

المصدر: Lecture Notes in Civil Engineering ISBN: 9783030645939

مصطلحات موضوعية: Vibration, Physics, Signal processing, Wave propagation, Acoustics, Ultrasonic sensor, Structural health monitoring, Time domain, Interference (wave propagation), Statistical signal processing

الوصف: In the last decades, ultrasonic guided waves have proven to be a promising tool for structural health monitoring (SHM). For a number of reasons, narrowband burst signals are widely used to excite structures in order to reduce the impact of multimodal wave propagation and dispersion. This paper addresses a different approach using broadband random excitation signals. While burst signals are advantageous for damage localization and compensation of environmental and operational conditions, the interference of stochastic waves resulting in a complex wavefield could be more sensitive to structural changes, including defects. Based on promising experimental results published recently, potentials and limitations resulting from random excitation are investigated in this paper. Sensor signals are simulated using the time domain spectral element method for a carbon fiber composite plate and twelve piezoelectric transducers. The simulated sensor signals are analyzed using different statistical methods, including the Nullspace-based Fault Detection algorithm known from vibration-based SHM, to compute damage indices for the intact and damaged states of the plate. Moreover, wavefield images computed by the root mean square (RMS) are presented. Detected defects and non-visible damage positions are compared and the results are discussed.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::6e043b92f3a9ae681c4a855abd4144dcTest
https://doi.org/10.1007/978-3-030-64594-6_76Test

المؤلفون: Junli Chen, Xiaolei Zhang, Yaowu Shen

المصدر: The 2021 International Conference on Machine Learning and Big Data Analytics for IoT Security and Privacy ISBN: 9783030895075

مصطلحات موضوعية: Artificial neural network, Computer science, Mobile manipulator, business.industry, Position (vector), Automotive industry, Robot, Radial basis function, Control engineering, Linear approximation, Interference (wave propagation), business

الوصف: With the advent of the intelligent era, intelligent industrial robots integrated with vision systems have penetrated into many fields. Especially robots with hand-eye functions play an important role in the fields of automobile manufacturing, logistics, and aviation exploration. Radial basis function (RBF) neural network has a high degree of non-linear mapping ability. This paper analyzes the structure characteristics, learning algorithm and application of RBF neural network in the robot eye-hand system, and analyzes the non-linearity of RBF neural network. The linear approximation characteristics are theoretically verified. The purpose of this article is to study the application of neural network algorithms in robot eye-hand systems. Simulation experiments show that the designed algorithm can track the ideal position well, and can significantly reduce chattering, and improve the control performance of the manipulator system when the system itself has uncertainty and external interference.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::055d76c39e3c0c539b941c73026d0f94Test
https://doi.org/10.1007/978-3-030-89508-2_15Test