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Статті в журналах з теми "Excitation transverse"
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Hosokawa, Shinya. "Transverse acoustic phonon excitations in liquid metals." Zeitschrift für Physikalische Chemie 235, no. 1-2 (August 10, 2020): 99–115. http://dx.doi.org/10.1515/zpch-2020-1626.
Повний текст джерелаАнотація:
Abstract In this article, transverse acoustic (TA) phonon excitations in various liquid metals are reviewed. Low-frequency TA phonon excitations were investigated on liquid Ga, Sn, Fe, Cu, Zn, and Bi, by using high energy resolution inelastic X-ray scattering (IXS). The current correlation functions obtained from the IXS spectra were analyzed by using two Gaussians to evaluate the excitation energies and widths of the longitudinal acoustic and TA excitation modes, which are consistent with ab initio molecular dynamics simulations. The lifetimes and propagating lengths of the TA modes were determined, and may respectively correspond to the lifetimes and sizes of cages instantaneously formed in each liquid metal. The microscopic elastic constants were estimated and characteristic differences from macroscopic polycrystalline values were found in Poisson’s ratios. Future experimental and analytical problems to be solved in the near future are addressed.
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Wang, Hongbo, and Shimin Dong. "Spatial Transverse Vibration Simulation Model of Axially Moving Sucker Rod String under the Excitation of Curved Borehole." Shock and Vibration 2020 (August 6, 2020): 1–18. http://dx.doi.org/10.1155/2020/3108718.
Повний текст джерелаАнотація:
The mechanical model of transverse vibration of sucker rod string (SRS) in directional well is simplified to the transverse vibration model of longitudinal and transverse curved beam with initial bending under borehole constraints. In this paper, besides considering the excitation of alternating axial load on the transverse vibration of SRS, it is proposed for the first time that curved borehole is also the main excitation for the transverse vibration when the SRS moves reciprocating axially in the borehole. Based on the elastic body vibration theory, the transverse vibration mathematical model of SRS with initial bending under borehole constraints is established. In this model, the curved borehole excitation caused by the axial motion and the alternating axial load excitation is considered. Besides, the elastic collision theory is applied to describe the constraint of tube on the SRS transverse vibration in this model. Then the fourth-order Runge–Kutta method is used to calculate the transverse vibration of SRS in directional wells. The simulation results show the following: (1) The simulation results of the three simulation models in this paper are different. The results indicate that the curved borehole excitation caused by the axial motion and the alternating axial load excitation is the main excitation for the SRS transverse vibration. (2) In directional wells, the rod and tube contact along the well depth, and the dangerous sections locate at the deviation section of the borehole and the compression section of the rod. On the whole, the contact force between rod and tube in deviation section of borehole is larger. The transverse vibration of the compression section of the rod is the most violent.
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Jasinska, Dorota, Joanna M. Dulinska, and Pawel Boron. "Influence of Spatial Variability of Seismic Shock on Steel Hall with Experimentally Determined Elasto-Plastic Parameters of Steel Material." Applied Mechanics and Materials 744-746 (March 2015): 884–89. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.884.
Повний текст джерелаАнотація:
In the paper the influence of spatial variability of a seismic shock on an industrial steel hall was examined. Different models of seismic excitation were introduced. Firstly, a uniform seismic excitation model was applied, assuming identical motion of all supports of the hall. Then, a non-uniform excitation model was implemented. In that model subsequent points of the ground in the direction of wave propagation repeat the same motion with a certain time delay dependent on the wave velocity. Two direction of the wave passage were assumed: longitudinal (along the longer side of the hall) and transverse (along the shorter side of the hall). To guarantee proper nonlinear elasto-plastic behavior of the structure, the material parameters of the steel were determined experimentally. The dynamic analyses revealed that the response of the hall to the seismic shock was reported beyond the elastic range. Plastic effects appeared in some zones of the primary as well as the secondary structural members of the object, regardless of the excitation model. The model of non-uniform seismic excitation with transverse wave passage turned out to have the greatest impact on the dynamic response of the hall; the plastic strains obtained for that model were much greater than those obtained for other models. The transverse non-uniform excitation generated irreversible strains almost 3 times greater than the uniform excitation. The evolution of significant plastic effects was observed mainly for non-uniform excitations in the lower parts (girts and columns) of the hall, which were strongly affected by the different motions of the ground.
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Yeh, Meng Kao, and Kuei Chang Tung. "Dynamic Instability of Delaminated Composite Plates under Parametric Excitation." Key Engineering Materials 326-328 (December 2006): 1765–68. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1765.
Повний текст джерелаАнотація:
The dynamic instability behavior of delaminated composite plates under transverse excitations was investigated experimentally and analytically. An electromagnetic device, acting like a spring with alternating stiffness, was used to parametrically excite the delaminated composite plates transversely. An analytical method, combined with the finite element method, was used to determine the instability regions of the delaminated composite plates based on the modal parameters of the composite plate and the position, the stiffness of the electromagnetic device. The delamination size and position of composite plates were varied to assess their effects on the excitation frequencies of simple and combination resonances in instability regions. The experimental results were found to agree with the analytical ones.
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Ding, Weigao, and Jin Xie. "A piezoelectric energy harvester for human body motion subjected to two different transversal reciprocating excitations." Mechanical Sciences 14, no. 1 (February 23, 2023): 77–86. http://dx.doi.org/10.5194/ms-14-77-2023.
Повний текст джерелаАнотація:
Abstract. Harvesting energy from human body motion to supply electricity for wearable devices is focused on in this paper. Based on the fact that the frequency of human body motion is lower and the motions of different human body parts are variable, a piezoelectric energy harvester subjected to two different transversal reciprocating excitations is studied in this paper. Each excitation is treated as a transverse rheonomic constraint. The dynamics equation of the beam is established using the Hamiltonian principle. Expressing the transverse rheonomic constraint as a periodic function, closed-form solutions of the dynamics equation are obtained. And the characteristics of energy harvesters are investigated based on the closed-form solutions. The results show that the difference between the two excitations will certainly cause the energy harvester to generate more output power at lower frequencies of excitations, and the larger the difference, the more the output power will be generated. This unusual characteristic at the lower frequency enables the proposed harvester to be quite suitable to harvest energy from the motions of the human body.
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Hao, Yu Xin, Wei Zhang, L. Yang, and J. H. Wang. "Dynamic Response of Cantilever FGM Cylindrical Shell." Applied Mechanics and Materials 130-134 (October 2011): 3986–93. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3986.
Повний текст джерелаАнотація:
An analysis on the nonlinear dynamics of a cantilever functionally graded materials (FGM) cylindrical shell subjected to the transversal excitation is presented in thermal environment.Material properties are assumed to be temperature-dependent. Based on the Reddy’s first-order shell theory,the nonlinear governing equations of motion for the FGM cylindrical shell are derived using the Hamilton’s principle. The Galerkin’s method is utilized to discretize the governing partial equations to a two-degree-of-freedom nonlinear system including the quadratic and cubic nonlinear terms under combined external excitations. It is our desirable to choose a suitable mode function to satisfy the first two modes of transverse nonlinear oscillations and the boundary conditions for the cantilever FGM cylindrical shell. Numerical method is used to find that in the case of non-internal resonance the transverse amplitude are decreased by increasing the volume fraction index N.
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Zhang, Shaohua, Yong Yuan, Yusheng Yang, Chong Li, and Herbert A. Mang. "Dynamic Performance of Soil–Tunnel System under Transverse Sinusoidal Excitations." Applied Sciences 11, no. 11 (May 31, 2021): 5097. http://dx.doi.org/10.3390/app11115097.
Повний текст джерелаАнотація:
Input of sinusoidal excitation with specified frequency is an optimal way to capture the mechanism of soil-tunnel interaction. Focusing on the relationship between the frequency of input sinusoidal motions and the dynamic response of a system, this study carried out a series of shaking table tests on both a free-field model and soil–tunnel model in the background of the tunnel in soft ground. To detect the detailed deformation of segmental linings, a refined lining ring of the model tunnel was developed, and the stiffness ratio between the soil and tunnel was verified. Seven sinusoidal excitations were designated to cover the fundamental frequency of the model ground, with the input of transverse direction. Effects of frequency of sinusoidal excitations on soil-tunnel interaction can be evaluated by the detailed responses of segmental linings, such as cross-sectional deformations, extension/closure of longitudinal joints, dynamic normal earth pressures, and dynamic strains of segments. Results shows that the differences of the acceleration responses, on the respects of waveform, phase, and peak, between the upper soil layer and the lower soil layer are obviously increasing with the input frequency increasing. The presence of the tunnel induces a relatively high effect on acceleration responses of the ground within excitation frequency varying from 9 to 17 Hz. The maximum responses of the tunnel are highly influenced by both the fundamental frequency of the model ground and lower frequency of excitations.
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Guo, Yongbo, Dekun Zhang, Xinyue Zhang, Songquan Wang, and Wan Ma. "Experimental Study on the Nonlinear Dynamic Characteristics of Wire Rope under Periodic Excitation in a Friction Hoist." Shock and Vibration 2020 (February 17, 2020): 1–14. http://dx.doi.org/10.1155/2020/8506016.
Повний текст джерелаАнотація:
The nonlinear dynamic responses of a wire rope under periodic excitation in a friction hoisting system are investigated. Longitudinal excitation experiments of different periodic excitation frequencies are performed. The nonlinear dynamic characteristics of the rope, including transverse, longitudinal, and coupled vibrations, are discussed with time-frequency analysis. The results show that the transverse vibration is a forced vibration following the excitation, while the longitudinal vibration shows a complex, random vibration state. The vibration amplitude and intensity deviate significantly from their linear trend (superharmonic resonance) at some excitation frequencies, and this deviation indicates the typical nonlinear multiorder natural frequency characteristics. The lifting motion can lead to additional corrugated high-order harmonics and cause a fundamental wave distortion of low-frequency excitation. Experimental evidence for the coupling characteristics of the transverse-longitudinal rope vibration in the lifting process is found.
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Yousefi, Yousef, and Khikmat Kh Muminov. "Quadrupole Excitation in Tunnel Splitting Oscillation in Nanoparticle." Advances in Condensed Matter Physics 2012 (2012): 1–4. http://dx.doi.org/10.1155/2012/530765.
Повний текст джерелаАнотація:
We analyze the interference between tunneling paths that occur for a spin system with special Hamiltonian both for dipole and quadrupole excitations. Using an instanton approach, we find that as the strength of the second-order transverse anisotropy is increased, the tunnel splitting for both excitations is modulated, with zeros occurring periodically and the number of quenching points for quadrupole excitation decreasing. This effect results from the interference of four tunneling paths connecting easy-axis spin orientations and occurs in the absence of any magnetic field.
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de Barros, Everaldo, Carlos d’Andrade Souto, and Mauro Hugo Mathias. "Experimental Observation Of Nonlinear Vibrations Using A Closed-Loop Vibration System." Metrology and Measurement Systems 22, no. 4 (December 1, 2015): 559–64. http://dx.doi.org/10.1515/mms-2015-0045.
Повний текст джерелаАнотація:
Abstract This paper presents experimental observation of nonlinear vibrations in the response of a flexible cantilever beam to transverse harmonic base excitations around its flexural mode frequencies. In the experimental setup, instead of manual control of the signal excitation frequency and amplitude, a closed-loop vibration system is used to keep the excitation amplitude constant during the frequency sweep and to increase confidence in the experimental results. The experimental results show the presence of the third mode in the response when varying the excitation frequency around the fourth mode. The frequency-response curves, response spectrum and Poincaré plots were used for characterization of nonlinear dynamic behaviour of the beam.
Дисертації з теми "Excitation transverse"
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O'Connor, Jacqueline. "Response of a swirl-stabilized flame to transverse acoustic excitation." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43756.
Повний текст джерелаАнотація:
This work addresses the issue of transverse combustion instabilities in annular gas turbine combustor geometries. While modern low-emissions combustion strategies have made great strides in reducing the production of toxic emissions in aircraft engines and power generation gas turbines, combustion instability remains one of the foremost technical challenges in the development of next generation combustor technology. To that end, this work investigates the response of a swirling flow and swirl-stabilized flame to a transverse acoustic field is using a variety of high-speed laser techniques, especially high-speed particle image velocimetry (PIV) for detailed velocity measurements of this highly unsteady flow phenomenon. A description of the velocity-coupled transverse instability mechanism is explained with companion measurements describing each of the velocity disturbance pathways. Dependence on acoustic frequency, amplitude, and field symmetry is discussed. Significant emphasis is placed on the response of a swirling flow field to a transverse acoustic field. Details of the dynamics of the vortex breakdown bubble and the shear layers are explained using a wide variety of measurements for both non-reacting and reacting flow cases. This thesis concludes with an overview of the impact of this work and suggestions for future research in this area.
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Davitian, Juliett. "Exploration and controlled excitation of transverse jet shear layer instabilities." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1790348231&sid=12&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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ELSHAMY, OMAR M. "EXPERIMENTAL INVESTIGATIONS OF STEADY AND DYNAMIC BEHAVIOR OF TRANSVERSE LIQUID JETS." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1179052529.
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Wroblewski, Adam Christopher. "Health Monitoring of Cracked Rotor Systems using External Excitation Techniques." Cleveland State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=csu1228312469.
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Bernot, Alix. "Modélisation et optimisation d'une machine électrique homopolaire en poudre de fer." Thesis, CentraleSupélec, 2015. http://www.theses.fr/2015SUPL0025/document.
Повний текст джерелаАнотація:
Cette thèse présente l’étude d’une machine électrique à stator à flux transverse à griffes. Après une étude du SMC et des structures à flux transverse, une structure associant un stator à griffes à un rotor à aimants permanents est choisie. Un modèle de la machine par réseau de réluctances est développé, en s’appuyant sur des simulations éléments finis. Il est ensuite amendé par l’introduction d’hypothèses d’inclinaison de flux dans l’entrefer, puis il est validé par le test d’un prototype. L’architecture est alors optimisée après une analyse détaillée de la circulation des flux, qui permet d’identifier le problème de la saturation du pied de dents. Après des simulations éléments finis de la machine améliorée, un prototype est ensuite testé qui confirme l’apport de la nouvelle architecture.Une version alternative de la machine, avec un bobinage d’excitation au stator et un rotor massif est ensuite proposée. Cette machine promet une fabrication économique et une bonne robustesse. Un modèle analytique est proposé, accompagné d’une étude éléments finis, puis pour finir un prototype est testé. Une version améliorée de cette machine avec un rotor à dents isolés est ensuite proposée : un modèle analytique et des études éléments finis permettent de valider l’intérêt de cette évolutionThis thesis presents the study of a claw-pole transverse flux electric machine. At first, SMC material properties and transverse flux structures are studied, leading to the choice of a structure combining a claw-pole stator and a permanent magnet rotor. The machine is modelled by the means of a magnetic equivalent circuit, with a reluctance network, developed with the help of finite elements simulation. The model is then changed with the introduction of the hypothesis that the flux is bent inside the airgap; it is then validated by the test of a prototype.The architecture of the machine is optimized after a detailed analysis of the flux circulation, leading to the identification of the tooth-tip saturation issue. After finite element simulation of the improved machine, a prototype is later tested, which confirms the gain brought by the new architecture.An alternative version of the machine, with a field winding attached to the stator and a massive rotor is then proposed. This machine promises to be cost-effective to build and robust thanks to its massive rotor. An analytical model of the machine is introduced, along with a finite element simulation, to end with the test of a prototype which confirms the possibilities of this new concept. An improved version of the machine with a rotor with isolated teeth is finally studied, with an analytical model and a finite element leading to the validation of the interest of this evolution
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Fiegle, Dominik [Verfasser], Tilmann [Akademischer Betreuer] Volk, and Ben [Gutachter] Fabry. "Preservation of the Transverse-Tubular System and Excitation-Contraction Coupling in Rodent and Human Ventricular Cardiomyocytes – Effects of Glucocorticoids and Autophagy / Dominik Fiegle ; Gutachter: Ben Fabry ; Betreuer: Tilmann Volk." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/1240903499/34.
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Rafik, Vincent. "Étude du dévissage d'un assemblage aéronautique sous sollicitations transverses." Electronic Thesis or Diss., Toulouse, INSA, 2019. http://www.theses.fr/2019ISAT0055.
Повний текст джерелаАнотація:
Cette thèse porte sur l’étude du dévissage spontané d’assemblages boulonnés sous sollicitations transverses. Plusieurs approches seront mises en place dans le but d’apporter des éléments participant à la compréhension du phénomène. Le développement d’un modèle complet permis la validation expérimentale tandis que des simulations simplifiées permettent d’identifier le glissement transverse de l’écrou, ou de la tête de vis, sur leurs plaques d’appui et le basculement des filets de la vis dans ceux de l’écrou. Les particularités de ces modèles sont la prise en compte de la plasticité, du serrage de l’assemblage par rotation de l’écrou, de son autofreinage et des filets. Par la suite, les paramètres clés furent déterminés à l’aide de deux campagne d’essais exploitant des assemblages à deux ou trois plaques : le revêtement de la vis, le niveau d’interférence, la précharge et l’amplitude de chargement. Dans l’objectif d’apprécier la répétabilité des résultats, des éprouvettes à double boulons furent testées. Enfin, un travail analytique se basant sur les observations numériques et expérimentales permis de proposer une formulation de l’effort nécessaire au dévissage de l’assemblage et de la vitesse de rotation des divers composantsThis thesis focuses on the study of the self-loosening of bolted joints under transverse loading. Several approaches will be put in place in order to provide elements contributing to the understanding of the phenomenon. The development of a complete model enabled experimental validation whereas simplified simulations highlighted the transverse sliding of the nut, or of the screw head, on their bearing surfaces and the tilting of the screw in the nut. The material’s plasticity, the tightening of the assembly by rotation of the nut, its self-braking and nets are taken into account in these models. Key parameters were defined using two test campaign of either two- or three-plate assemblies: screw coating, interference level, preload, and loading amplitude. In order to assess the repeatability of the results, double-bolt specimens were tested. Finally, thanks to an analytical work based on numerical and experimental observations, a formulation of the effort required to unscrew the assembly and the speed of rotation of the various components was proposed
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Desclaux, Anthony. "Etude expérimentale du comportement linéaire et non linéaire d’une flamme diphasique soumise à une excitation acoustique. Mise en œuvre d’une méthode de contrôle adaptative." Thesis, Toulouse, ISAE, 2020. http://depozit.isae.fr/theses/2020/2020_Desclaux_Anthony_D.pdf.
Повний текст джерелаАнотація:
Cette thèse de doctorat se place dans la continuité de l’effort engagé par l’ONERA sur la compréhensiondes mécanismes de stabilisation des flammes diphasiques dans les moteurs aéronautiques. Ces travauxconcernent plus particulièrement la dynamique de sprays et de flammes perturbés par des ondes acoustiques.Ils étudient le rôle de l’injection de carburant liquide sur la réponse non linéaire de flammes stabilisée à l’avald’un injecteur industriel multipoint à zone centrale pilote. Sur la base de travaux antérieurs, l’objectif premierest d’étudier l’influence de perturbations acoustiques sur le comportement de l’injection de carburant liquide.Pour cela, une première configuration expérimentale simplifiée analyse l’influence de perturbationsacoustiques sur le comportement d’un jet liquide débouchant transversalement dans un écoulement d’air.Les résultats mettent en évidence les mécanismes d’atomisation du jet ainsi que son interaction avec desperturbations acoustiques. L’étude des phénomènes de transport du brouillard de gouttes montrel’apparition d’ondes de densité de gouttes. L’influence de la taille des gouttes sur ces phénomènes estcaractérisée. Le second objectif de ces travaux est d’analyser le comportement d’une flamme diphasique(kérosène/air) en présence d’excitations acoustiques. Dans ce cas, une deuxième configurationexpérimentale est mise en œuvre. Elle reproduit de manière réaliste les phénomènes rencontrés dans leschambres de combustion. Ce travail utilise l’approche « Flame Describing Function » (FDF). Pour cela, lesfluctuations du taux de dégagement de chaleur de la flamme sont caractérisées à partir d’une méthodeoriginale basée sur la mesure simultanée de la chimiluminescence de plusieurs radicaux. Les résultats sontobtenus pour deux configurations d’injection, l’une utilisant la zone pilote seul et l’autre l’injecteur dans sonintégralité. L’analyse des FDF met en évidence des phénomènes de saturation qui limitent la réponse de laflamme. La comparaison des résultats entre les deux configurations d'injection montre que le retard entre laréponse de la flamme et les perturbations de l’écoulement est fortement influencé par le mode d’injection.L’ensemble des résultats obtenus dans ces travaux constituent une base de donnée expérimentale pourvalider des simulations LES réactives et pour fournir un modèle de description du comportement de laflamme à des codes de simulation « bas ordre »This PhD thesis supports the effort undertaken by ONERA to understand the mechanisms of stabilizationof two-phase flames in aeronautical engines. This work concerns more particularly the dynamics of spraysand flames disturbed by acoustic waves. This work studies the role of liquid fuel injection on the non-linearresponse of stabilized flames downstream of an industrial multipoint injector with a central pilot zone. Basedon previous work, the first objective is to study the influence of acoustic disturbances on the behavior ofliquid fuel injection in the multipoint zone. The observed phenomena are reproduced, in an idealized form,from a simplified experimental set up based on the configuration of a liquid jet injected into air crossflowsubmitted to an acoustic forcing. The results highlight the atomization mechanisms of the jet and itsinteraction with acoustic disturbances. The study of the spray shows the appearance of droplet densitywaves. The influence of drop size on these phenomena is characterized. The second objective of this workis to analyze the behavior of a two-phase flame (kerosene/air) disturbed by acoustic excitations. In this case,a second experimental configuration is implemented. This experimental set up reproduces in a realistic waythe phenomena encountered in combustion chambers. This work uses the "Flame Describing Function"(FDF) approach. In order to do this, the fluctuations of the heat release rate from the flame are characterizedusing an original method based on the simultaneous measurement of the chemiluminescence of severalradicals. The results are obtained for two injection configurations, one using the pilot zone alone and theother using the entire injector. The analysis of the FDFs reveals saturation phenomena which limit the flameresponse. Comparison of the results between the two injection configurations shows that the delay betweenflame response and flow disturbances is strongly influenced by the injection mode. All the results obtainedin this work constitute an experimental database to validate reactive LES simulations and to provide a modelfor describing the flame behavior in simulations based on "low order" approaches
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Jiang, Xianwu. "Hydrocarbon molecules databases for waste treatment applications." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPAST039.
Повний текст джерелаАнотація:
Dans cette thèse, nous étudions la (dé)excitation vibronique et la recombinaison dissociative du CH+ par impact d'électrons de faible énergie. Nous développons d'abord une approche théorique de l'excitation (dé)vibronique de CH+ par impact d'électrons. Dans cette approche, la méthode de la matrice R à noyaux fixes est utilisée pour calculer les matrices de diffusion des électrons et des ions dans l'approximation de Born-Oppenheimer. Une transformation vibronique du cadre et la procédure d'élimination à canal fermé dans l'esprit de la théorie des défauts quantiques moléculaires sont utilisées pour construire une matrice de diffusion dépendant de l'énergie décrivant les interactions entre les canaux vibroniques de l'ion cible induits par l'électron incident. La matrice de diffusion obtenue tient compte de la série de résonances vibroniques de Rydberg dans le spectre de collision. Les sections transversales de l'excitation vibronique pour différentes combinaisons d'états vibroniques initiaux et finaux sont calculées. Un bon accord entre les sections transversales d'excitation électronique, obtenu en utilisant la théorie des défauts quantiques et dans un calcul direct de matrice R, démontre que l'approche actuelle fournit un outil fiable pour la détermination des sections transversales d'excitation (dé)vibronique pour des cibles avec des résonances électroniques de faible énergie. De telles cibles étaient difficiles à traiter théoriquement avec les méthodes précédentes. Dans le même cadre que celui appliqué aux excitations (dé)vibroniques, nous calculons en outre la section transversale pour la recombinaison dissociative à basse énergie de CH+ couplant la fonction de base de l'onde sortante définie par le potentiel d'absorption complexe. La contribution des trois états ioniques X 1Σ +, a 3Π et A 1Π les plus bas et la série de Rydberg convergeant vers ces états sont pris en compte. Les sections transversales DR obtenues sont quantitativement en bon accord avec les mesures expérimentales et présentent une caractéristique de résonance analogue à la courbe de la section transversale expérimentale. L'origine des résonances proéminentes dans les résultats calculés est analysée par le calcul des probabilités de DR pour les ondes partielles de l'électron incident. On constate que les ondes partielles de type d, notamment dσ, dπ et dδ, contribuent considérablement à la DR du état de terrain CH+. Cela peut expliquer les écarts observés entre la théorie et l'expérience dans les études précédentesIn this thesis, we investigate the vibronic (de-) excitation and dissociative recombination of CH+ by low-energy electron impact. We first develop a theoretical approach for the electron-impact vibronic (de-) excitation of CH+. In this approach, the fixed-nuclear R-matrix method is employed to compute electron-ion scattering matrices in the Born-Oppenheimer approximation. A vibronic frame transformation and the closedchannel elimination procedure in a spirit of molecular quantum defect theory are employed to construct an energy-dependent scattering matrix describing interactions between vibronic channels of the target ion induced by the incident electron. The obtained scattering matrix accounts for Rydberg series of vibronic resonances in the collisional spectrum. Cross sections for vibronic excitation for different combinations of initial and final vibronic states are computed. A good agreement between electronic-excitation cross sections, obtained using the quantum defect theory and in a direct R-matrix calculation, demonstrates that the present approach provides a reliable tool for determination of vibronic (de-) excitation cross sections for targets with low-energy electronic resonances. Such targets were difficult to treat theoretically using earlier methods. Within the same framework applied for the vibronic (de-) excitations, we further compute the cross section for low-energy dissociative recombination of CH+ coupling the outgoing-wave basis function defined by complex absorbing potential. The contribution of the three lowest X 1Σ +, a 3Π and A 1Π ionic states and the Rydberg series converging to those states are taken into account. The obtained DR cross sections are quantitatively in good agreement with the experimental measurements and exhibit a resonanc feature analogous to the experimental cross-section curve. The origination of the prominant resonances in the computed results are analyzed through computing the DR probabilities for the partial waves of the incident electron. The d-type partial waves including dσ, dπ and dδ are found considerably contributing to the DR of the ground-state CH+. This may explain the discrepancies observed between thoery and experiment in the preceeding studies
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Courtois, Jérémie. "Développements de systèmes multipassages pour application à la spectroscopie d'absorption : Cavity Ring Down Spectroscopy multimode et cellules à passages multiples." Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00458101.
Повний текст джерелаАнотація:
La spectroscopie d'absorption par mesure du temps de vie des photons piégés dans une cavité optique haute-finesse, ou Cavity Ring Down Spectroscopy (CRDS), compte parmi les outils de diagnostic optique les plus sensibles. L'excitation « mode matchée » d'un laser continu rapidement et continûment balayé (~4 THz.s-1 durant ~2 ms), i.e. la cw-CRDS monomode rapide, garantit à la technique ses meilleures performances en termes de limites de détectivité avec, en contrepartie, des points de mesures séparés de l'Intervalle Spectral Libre du résonateur (ISL=c/2L) : le dosage d'environnements basse pression requiert de longues cavités. Cette étude originale propose de mettre à profit la structure transverse du résonateur afin de rendre possible la miniaturisation du dispositif de cw-CRDS rapide. L'excitation multimode d'une cavité fractionnellement dégénérée (dite de taille « magique »), ici présentée, permet de bénéficier d'un gain d'échantillonnage spectral qui vaut l'ordre réentrant N employé. Nous développons deux schémas d'injection multimode : l'injection multimode axiale et l'injection multimode réentrante, dite dans ce dernier cas hors de l'axe optique, de telles cavités et nous en étudions les principales différences. Une étude détaillée du champ intracavité existant aux N résonances constitutives de l'ISL est proposée afin de rendre compte des limites de détectivités associées à ces deux schémas d'injection multimode sensiblement distincts. Une seconde partie de ce travail de thèse est dédiée à caractériser de façon approfondie l'observation des profils spatiaux intracavités formés en injection hors axe lorsque la cavité souffre d'un faible astigmatisme (ΔR/R~2 %) : on parle de profil de Lissajous. Cette étude rend compte des mécanismes fondamentaux, telle la coïncidence particulière de modes particuliers par dispersion modale, qui aboutissent en un intervalle millimétrique de dégénérescence. Celui-ci est le siège d'une succession de profils transverses de Lissajous symétriques les uns des autres de part et d'autre d'une taille particulière de cavité : nous en précisons les causes. Le résiduel astigmatisme ainsi mis en évidence et mesuré permet, en outre, d'expliquer la disparition des oscillations Doppler normalement présentent en début de décroissance ring down dans ce type d'injection dynamique. De façon connexe, nous développons plusieurs types de cellules multipassages non-résonantes comme alternative à la CRDS pour le dosage d'environnements hostiles.
Книги з теми "Excitation transverse"
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Kudinov, Igor', Anton Eremin, Konstantin Trubicyn, Vitaliy Zhukov, and Vasiliy Tkachev. Vibrations of solids, liquids and gases taking into account local disequilibrium. ru: INFRA-M Academic Publishing LLC., 2022. http://dx.doi.org/10.12737/1859642.
Повний текст джерелаАнотація:
The monograph presents the results of the development and research of new mathematical models of the processes of vibrations of solids, liquids and gases, taking into account local disequilibrium. To derive differential equations, the Navier—Stokes equations, Newton's second law and modified formulas of the classical empirical laws of Fourier, Hooke, Newton are used, which take into account the velocities and accelerations of the driving forces (gradients of the corresponding quantities) and their consequences (heat flow, normal and tangential stresses). The conditions for the occurrence of shock waves of stresses and displacements in dynamic thermoelasticity problems formulated taking into account relaxation phenomena in thermal and thermoelastic problems are investigated, new results are obtained in the study of longitudinal and transverse vibrations of rods, strings, liquids and gases, and the conditions for the excitation of gas self-oscillations arising from a time-constant heat source are determined.
It is intended for scientific and technical workers specializing in mathematics, thermophysics, thermoelasticity, as well as teachers and students of technical universities.
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Matta, James Till. Exotic Nuclear Excitations: The Transverse Wobbling Mode in 135 Pr. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-53240-0.
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Matta, James Till. Exotic Nuclear Excitations: The Transverse Wobbling Mode in 135 Pr. Springer, 2017.
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Matta, James Till. Exotic Nuclear Excitations: The Transverse Wobbling Mode in 135 Pr. Springer, 2018.
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Asai, H. Theoretical Study of THz Emission from HTS Cuprate. Edited by A. V. Narlikar. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780198738169.013.9.
Повний текст джерелаАнотація:
This article examines the THz emission from high-temperature superconducting (HTS) cuprates in the mesoscopic state using the intrinsic Josephson junction model. Cuprate superconductors are high-temperature superconductors that exhibit exotic electromagnetic properties. One of the remarkable features of HTS cuprates is high anisotropy due to their layered structures. Almost all HTS cuprates are composed of stacks of CuO2 layers and blocking layers which supply charge carriers to the CuO2 layers. The crystal structures of the HTS cuprates naturally form Josephson junctions known as intrinsic Josephson junctions (IJJs). This article first describes the basic theory of IJJ and the mechanism of THz emission before discussing the effect of temperature inhomogeneity on the emission properties. It then introduces a novel IJJ-based THz emitter that utilizes laser heating. Theoretical results show that the THz emission is caused by the strong excitation of transverse Josephson plasma waves in IJJs under a direct current bias.
Частини книг з теми "Excitation transverse"
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Bernot, Francois, Alix Bernot, and Jean-Claude Vannier. "A Synchronous Wound Excitation Transverse Flux Machine with Solid Rotor." In Lecture Notes in Mechanical Engineering, 25–39. New Delhi: Springer India, 2014. http://dx.doi.org/10.1007/978-81-322-1871-5_5.
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Deng, Xiujie. "SSMB Transverse-Longitudinal Coupling Dynamics." In Springer Theses, 51–87. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-5800-9_3.
Повний текст джерелаАнотація:
AbstractAfter dedicated efforts devoted to the longitudinal dynamics to realize an ultrasmall longitudinal emittance and ultrashort bunch length for coherent radiation generation, we need to make sure that the coupling arising from transverse dynamics does not degrade or even destroy the longitudinal fine structures. Such an argument is based on the observation that the transverse beam size in an SSMB ring can be orders of magnitude larger than the desired microbunch length. This is the basic motivation for us to investigate the transverse-longitudinal coupling (TLC) dynamics. In this chapter, we start from the linear TLC and then investigate the nonlinear TLC dynamics. For the linear dynamics, first we analyze the passive bunch lengthening induced by bending magnets. We then emphasize the fact that TLC can actually be actively applied for efficient bunch compression and high harmonic generation when the transverse emittance is small. We present three theorems on the application of such TLC schemes, with their implications discussed. Further, we have analyzed the contribution of modulators to the vertical emittance from quantum excitation, to obtain a self-consistent evaluation of the required modulation laser power when applying these coupling schemes in a storage ring. The theorems and related analysis provide the theoretical basis for the application of TLC in SSMB to lower the requirement on the modulation laser power, by taking advantage of the fact that the vertical emittance in a planar ring is rather small. Based on the investigations, we have presented example parameters sets for the envisioned SSMB storage ring to generate high-power EUV and soft X-ray radiation at the end of this dissertation.
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Zhao, Yong Gang, Wei Dong Zhao, Shi Rong Li, and Lian Sheng Ma. "Nonlinear Response of Clamped Circular Plates Subjected to Transverse Excitation Load." In Key Engineering Materials, 2720–23. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-456-1.2720.
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Mirsaidov, Mirziyod, Olimjon Dusmatov, and Muradjon Khodjabekov. "Mode Shapes of Transverse Vibrations of Rod Protected from Vibrations in Kinematic Excitations." In Lecture Notes in Civil Engineering, 217–27. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-79983-0_20.
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Wang, Qi, and Yong Yuan. "Shaking table test of segmental linings with Ground-Penetrating Shield Tunnel (GPST) under transverse excitations." In Expanding Underground - Knowledge and Passion to Make a Positive Impact on the World, 3327–34. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003348030-403.
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Schlaad, K. H., Ch Weber, U. Zimmermann, G. Weimann, C. v. Hoof, G. Borghs, and C. Klingshirn. "Nonlinear Optical Properties of GaAs/(AlGa) As Multiple Quantum Wells Under Quasistationary High Laser Excitation and Transversal Electric Fields." In Optical Information Technology, 3–12. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78140-7_1.
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Kuperman, Vadim. "Excitation of the Transverse Magnetization." In Magnetic Resonance Imaging, 29–40. Elsevier, 2000. http://dx.doi.org/10.1016/b978-012429150-8/50004-8.
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Kozerke, Sebastian, Redha Boubertakh, and Marc Miquel. "Basic MR physics." In The EACVI Textbook of Cardiovascular Magnetic Resonance, edited by Massimo Lombardi, Sven Plein, Steffen Petersen, Chiara Bucciarelli-Ducci, Emanuela R. Valsangiacomo Buechel, Cristina Basso, and Victor Ferrari, 6–10. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198779735.003.0002.
Повний текст джерелаАнотація:
In magnetic resonance, the properties of protons in tissue giving rise to so-called magnetic moments are exploited. The sum of many magnetic moments yields what is referred to as net magnetization, which can be seen as similar to the magnetization a bar magnet produces. The relation and interaction between magnetic moments, net magnetization, the static magnetic field, and radiofrequency fields are discussed. It is shown that radiofrequency excitation can be used to manipulate the net magnetization, such that it can be detected using radiofrequency antennae or coils. Upon excitation, the net magnetization will recover back to its equilibrium orientation with tissue-specific time constants for the transverse and longitudinal components, which, in turn, are important sources of image contrast in cardiac imaging. The discussion concludes with a foray into susceptibility and chemical shift effects resulting from different molecular environments in which protons can reside and which provide additional image contrast mechanisms.
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Keser, Anabel, Michiel Verdult, Harleigh Seyffert, and Apostolos Grammatikopoulos. "The Design, Production, Verification, and Calibration of an Elastic Model of a Catamaran for Hydroelastic Experiments." In Progress in Marine Science and Technology. IOS Press, 2023. http://dx.doi.org/10.3233/pmst230019.
Повний текст джерелаАнотація:
Catamarans are popular in the offshore sector as they combine good transverse stability and ample deck space with low wave resistance. However, their slender hull shape results in low restoring qualities in heave and pitch motions. The large motions in rough weather can often result in water impacting the underside of the deck connecting the two hulls, a phenomenon called wet deck slamming. The impulse excitation from wet deck slamming can then produce a transient hydroelastic response of the structure called whipping. Whipping excites mode shapes that would not normally be present in the response, as their natural frequencies are significantly higher than the wave encounter frequency. This results in detrimental contributions to fatigue life through high-amplitude cyclical bending moments. Both the calculation of slamming loads and the prediction of resulting structural responses have been a challenge for several decades. The highly nonlinear and three-dimensional character of the phenomenon, combined with the strongly coupled fluid-structure interaction means that it is unpredictable, and even the definition of slamming events has been a matter of disagreement among researchers. Experiments are still a vital part of these investigations, for validating ever-improving numerical techniques. An essential issue with experiments is the extent to which mode shapes and natural frequencies can be emulated in model scale. Traditional hydroelastic models are segmented and use either a flexible backbone or flexible joints to introduce stiffness. This often results in an excellent description of the 2-node bending mode, but an increasing error for higher modes leads to stress inaccuracies. In this investigation, a continuous model of a catamaran is designed and produced for hydroelastic experiments. The advantages and limitations of the concept are identified, the verification against structural models is presented, and the calibration of the measurements is discussed.
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Loudon, Rodney. "Single-mode quantum optics." In The Quantum Theory of Light, 180–232. Oxford University PressOxford, 2000. http://dx.doi.org/10.1093/oso/9780198501770.003.0006.
Повний текст джерелаАнотація:
Abstract The theory of the electromagnetic field quantization developed in Chapter 4 simplifies considerably for applications Lo many of the key experiments in quantum optics. Thus many experiments use plane parallel light beams whose transverse intensity profiles are not important for the measured quantities. Again, it is often sufficient in interpreting the data to consider the light beams as exciting a single mode of the field. The present chapter begins with the specialization of the quantization to single-mode excitations. The quantum theory is illustrated by its application to several varieties of single-mode state and the main features of number Cates, coherent states, chaotic statistical mixtures and squeezed states are derived.
Тези доповідей конференцій з теми "Excitation transverse"
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Baker, H. J., and D. N. Brawley. "Transverse if excitation of metal vapor lasers." In Conference on Lasers and Electro-Optics. Washington, D.C.: OSA, 1986. http://dx.doi.org/10.1364/cleo.1986.we4.
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Nicholls, Chris, Kharthik Chakravarthy, Brian Tang, Ben A. Williams, and Marko Bacic. "Reattaching jet response to transverse acoustic excitation." In AIAA AVIATION 2023 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2023. http://dx.doi.org/10.2514/6.2023-3890.
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Iyoda, Mitsuhiro, Yuta Yasumatus, Masamori Endo, Taizo Masuda, Kiyoto Sasaki, and Tomohiro Yamashita. "Solar-pumped fiber laser with transverse-excitation geometry." In Fiber Lasers XV: Technology and Systems, edited by Adrian L. Carter and Ingmar Hartl. SPIE, 2018. http://dx.doi.org/10.1117/12.2288940.
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Hardi, J. S., and M. Oschwald. "Cryogenic oxygen jet response to transverse acoustic excitation with the first transverse and the first combined longitudinal-transverse modes." In Progress in Propulsion Physics, edited by M. Calabro, L. DeLuca, S. Frolov, L. Galfetti, and O. Haidn. Les Ulis, France: EDP Sciences, 2016. http://dx.doi.org/10.1051/eucass/201608075.
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Pleshkova, T. A., A. P. Pushkov, and N. G. Repkina. "Dynamic Stability of Synchronous Turbogenerators with Longitudinally-Transverse Excitation." In 2018 International Conference on Industrial Engineering, Applications and Manufacturing (ICIEAM). IEEE, 2018. http://dx.doi.org/10.1109/icieam.2018.8729139.
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Baev, R. "Excitation and Propagation of Subsurface Vertically Polarized Transverse Waves." In REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION. AIP, 2005. http://dx.doi.org/10.1063/1.1916664.
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Schock, W., Th Hall, E. Wildermuth, K. Wessel, E. Gehringer, P. Schnee, and F. Hadinger. "Compact Transverse Flow CO 2 Laser With RF Excitation." In 7th Intl Symp on Gas Flow and Chemical Lasers, edited by Dieter Schuoecker. SPIE, 1989. http://dx.doi.org/10.1117/12.950503.
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Bel'kov, S. A., Sergei V. Bondarenko, Yu V. Dolgopolov, V. A. Eroshenko, Gennady G. Kochemasov, Stanislav M. Kulikov, M. N. Solov'eva, Stanislav A. Sukharev, and I. N. Voronich. "Investigation of the transverse SBS excitation in anisotropic crystals." In Laser Optics '95, edited by Vladimir E. Sherstobitov. SPIE, 1996. http://dx.doi.org/10.1117/12.238077.
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Eroshenko, V. A., Sergei V. Bondarenko, and Gennady G. Kochemasov. "Computer modeling of transient transverse SBS excitation in anisotropic crystals." In Solid State Lasers for Application to Inertial Confinement Fusion (ICF), edited by Michel Andre and Howard T. Powell. SPIE, 1995. http://dx.doi.org/10.1117/12.228277.
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Bel'kov, S. A., Yu V. Dolgopolov, Gennady G. Kochemasov, Stanislav M. Kulikov, M. N. Solov'eva, Stanislav A. Sukharev, and I. N. Voronich. "Experimental investigation of the transverse SBS excitation in anisotropic crystals." In Solid State Lasers for Application to Inertial Confinement Fusion (ICF), edited by Michel Andre and Howard T. Powell. SPIE, 1995. http://dx.doi.org/10.1117/12.228310.
Повний текст джерелаЗвіти організацій з теми "Excitation transverse"
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Mojidra, Rushil, and Keri Ryan. Influence of Vertical Ground Motion on Bridges Isolated with Spherical Sliding Bearings. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, December 2019. http://dx.doi.org/10.55461/rynq3624.
Повний текст джерелаАнотація:
The motivation for this project developed from testing of a full scale building isolated with triple friction pendulum bearings on the E-defense shake table in Japan. The test demonstrated experimentally that the vertical component of ground motion can amplify both the base shear and the story acceleration in the isolated building. Vertical shaking introduced high-frequency variation in the axial force of the bearings, and, consequently, a high-frequency component in the bearing lateral force, which excited higher structural modes in the building. Since vertical bridges are flexible in the vertical direction because of long spans, similar effects may be observed in bridges. The objectives of this study are to develop a physical understanding of the amplification of responses and develop a simplified method to predict amplification of base shear in three-dimensional (3D) shaking relative to two-dimensional (2D) shaking, for bridges isolated with spherical sliding bearings. A series of ground motions with a wide range of vertical shaking intensity were applied to 3D models of bridges isolated with triple pendulum bearings (TPBs), both excluding the vertical component (2D motion) and including the vertical component (3D motion). This enabled the comparison of the bridge response under 2D and 3D shaking such that the direct effect of vertical shaking could be investigated. The selected ground motions were fit to target spectra in the horizontal and vertical directions, and divided into three groups based on vertical peak ground acceleration (PGAV). Multi-span concrete box girder bridges were selected for this study, as they are a prominent bridge type in California, and are suitable for seismic isolation. Models were developed for a 3-span, 45-ft wide, multi-column Base Model bridge; various superstructure and isolation-system parameter variations were implemented to evaluate the effect of these variations on the amplification of base shear. Response histories were compared for a representative motion from each ground-motion group under 2D and 3D shaking. Modal and spectral analyses were conducted to understand dynamic properties and behavior of the bridge under vertical motion. Based on simplified theory, a method to estimate the amplification of base shear due to vertical shaking was developed. The accuracy of the simplified method was assessed through a base shear normalized error metric, and different amplification factors were considered. Response history analysis showed significant amplification of base shear under 3D motion implying that exclusion of vertical component could lead to under estimation of demand shear forces on bridge piers. Deck acceleration spectral response at different locations revealed that a transverse-vertical modal coupling response was present in the Base Model bridge, which led to amplification of deck accelerations in addition to base shear due to excitation of the superstructure transverse mode. The simplified method predicted that in addition to the peak vertical ground acceleration base shear amplification depended on the isolation-system period (radius of curvature) and friction coefficient. The error in the simplified method was approximately constant across the range of isolation-system parameters. Variations in the bridge superstructure or substructure modeling parameters had only a minor effect on the base shear since the deck acts as a single mass sliding on isolators; therefore, the simplified method can be applied to a range of bridge models. The simplified method includes an amplification factor that indirectly represents the dynamic amplification of vertical acceleration from the ground to the isolation system. An amplification factor of 1.0 was found to be sufficiently conservative to estimate the base shear due to 3D shaking. The lack of apparent dynamic amplification could mean that the peak vertical acceleration is out-of-phase with the base shear. The simplified method is more likely to be unconservative for high-intensity vertical ground motions due to the complexities associated with uplift and pounding. Further investigation is recommended to determine the threshold shaking intensity limit for the simplified method.
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Wu, Yingjie, Selim Gunay, and Khalid Mosalam. Hybrid Simulations for the Seismic Evaluation of Resilient Highway Bridge Systems. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, November 2020. http://dx.doi.org/10.55461/ytgv8834.
Повний текст джерелаАнотація:
Bridges often serve as key links in local and national transportation networks. Bridge closures can result in severe costs, not only in the form of repair or replacement, but also in the form of economic losses related to medium- and long-term interruption of businesses and disruption to surrounding communities. In addition, continuous functionality of bridges is very important after any seismic event for emergency response and recovery purposes. Considering the importance of these structures, the associated structural design philosophy is shifting from collapse prevention to maintaining functionality in the aftermath of moderate to strong earthquakes, referred to as “resiliency” in earthquake engineering research. Moreover, the associated construction philosophy is being modernized with the utilization of accelerated bridge construction (ABC) techniques, which strive to reduce the impact of construction on traffic, society, economy and on-site safety. This report presents two bridge systems that target the aforementioned issues. A study that combined numerical and experimental research was undertaken to characterize the seismic performance of these bridge systems. The first part of the study focuses on the structural system-level response of highway bridges that incorporate a class of innovative connecting devices called the “V-connector,”, which can be used to connect two components in a structural system, e.g., the column and the bridge deck, or the column and its foundation. This device, designed by ACII, Inc., results in an isolation surface at the connection plane via a connector rod placed in a V-shaped tube that is embedded into the concrete. Energy dissipation is provided by friction between a special washer located around the V-shaped tube and a top plate. Because of the period elongation due to the isolation layer and the limited amount of force transferred by the relatively flexible connector rod, bridge columns are protected from experiencing damage, thus leading to improved seismic behavior. The V-connector system also facilitates the ABC by allowing on-site assembly of prefabricated structural parts including those of the V-connector. A single-column, two-span highway bridge located in Northern California was used for the proof-of-concept of the proposed V-connector protective system. The V-connector was designed to result in an elastic bridge response based on nonlinear dynamic analyses of the bridge model with the V-connector. Accordingly, a one-third scale V-connector was fabricated based on a set of selected design parameters. A quasi-static cyclic test was first conducted to characterize the force-displacement relationship of the V-connector, followed by a hybrid simulation (HS) test in the longitudinal direction of the bridge to verify the intended linear elastic response of the bridge system. In the HS test, all bridge components were analytically modeled except for the V-connector, which was simulated as the experimental substructure in a specially designed and constructed test setup. Linear elastic bridge response was confirmed according to the HS results. The response of the bridge with the V-connector was compared against that of the as-built bridge without the V-connector, which experienced significant column damage. These results justified the effectiveness of this innovative device. The second part of the study presents the HS test conducted on a one-third scale two-column bridge bent with self-centering columns (broadly defined as “resilient columns” in this study) to reduce (or ultimately eliminate) any residual drifts. The comparison of the HS test with a previously conducted shaking table test on an identical bridge bent is one of the highlights of this study. The concept of resiliency was incorporated in the design of the bridge bent columns characterized by a well-balanced combination of self-centering, rocking, and energy-dissipating mechanisms. This combination is expected to lead to minimum damage and low levels of residual drifts. The ABC is achieved by utilizing precast columns and end members (cap beam and foundation) through an innovative socket connection. In order to conduct the HS test, a new hybrid simulation system (HSS) was developed, utilizing commonly available software and hardware components in most structural laboratories including: a computational platform using Matlab/Simulink [MathWorks 2015], an interface hardware/software platform dSPACE [2017], and MTS controllers and data acquisition (DAQ) system for the utilized actuators and sensors. Proper operation of the HSS was verified using a trial run without the test specimen before the actual HS test. In the conducted HS test, the two-column bridge bent was simulated as the experimental substructure while modeling the horizontal and vertical inertia masses and corresponding mass proportional damping in the computer. The same ground motions from the shaking table test, consisting of one horizontal component and the vertical component, were applied as input excitations to the equations of motion in the HS. Good matching was obtained between the shaking table and the HS test results, demonstrating the appropriateness of the defined governing equations of motion and the employed damping model, in addition to the reliability of the developed HSS with minimum simulation errors. The small residual drifts and the minimum level of structural damage at large peak drift levels demonstrated the superior seismic response of the innovative design of the bridge bent with self-centering columns. The reliability of the developed HS approach motivated performing a follow-up HS study focusing on the transverse direction of the bridge, where the entire two-span bridge deck and its abutments represented the computational substructure, while the two-column bridge bent was the physical substructure. This investigation was effective in shedding light on the system-level performance of the entire bridge system that incorporated innovative bridge bent design beyond what can be achieved via shaking table tests, which are usually limited by large-scale bridge system testing capacities.
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VIBRO-ACOUSTICAL PERFORMANCE OF A STEEL BEAM OF GROOVE PROFILE: FIELD TEST AND NUMERICAL ANALYSIS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.063.
Повний текст джерелаАнотація:
To meet the development needs of rail transit, steel beams are more widely used in bridges, which brings more significant vibration and noise problems. In this paper, the dynamic characteristics of a steel beam of groove profile are investigated through field test and numerical analysis. Firstly, under the hammering excitation, the vibration response of the slabs in a descending order are right web, left web and bottom slab. The vibration response is related to the distance from the response position to the excitation source and the stiffness of slabs. Then, a numerical model of the steel beam is established based on the hybrid FE-SEA method. The results of field test are consistent with the numerical simulation, which confirms the effectiveness of the hybrid FE-SEA method when analyzing the steel beam. Finally, by comparing the sound power level radiated from different slabs in three zones, it can be concluded that the sound power level is related to the distance from the test position to the excitation source. The overall sound power level will increase when canceling transverse connection system, and center excitation has a more significant effect than off-center excitation.