Academic literature on the topic 'Modal summation method'
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Journal articles on the topic "Modal summation method"
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La Mura, C., T. B. Yanovskaya, F. Romanelli, and G. F. Panza. "Three-Dimensional Seismic Wave Propagation by Modal Summation: Method and Validation." Pure and Applied Geophysics 168, no. 1-2 (May 22, 2010): 201–16. http://dx.doi.org/10.1007/s00024-010-0165-2.
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Qiu, Ju, Wei Lian, Huaxiang Rao, Caiyun Wang, Tengteng Luo, and Jiali Tang. "Localization of Vibration Weak Position of Composites Based on Weighted Modal Strain Energy Summation." Journal of Composites Science 6, no. 11 (October 31, 2022): 324. http://dx.doi.org/10.3390/jcs6110324.
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In this paper, two typical examples are used to illustrate the weak position of aircraft structure in the process of vibration. Through the modal analysis of the typical composite plate and I-shaped beam, the first 20-order modal strain energy of the plate is extracted, which is difficult to locate the weak spot due to the highly scattered location of the higher modal strain energy. The modal participation factor is introduced as the weight factor of the summation of the modal strain energy. The modal participation factor is large, the weighting factor is large, and the high modal strain energy of the composite plate moves diagonally in the 45° direction of the composite plate and the high strain energy region is consistent with the previous modes of the plate. This is the result of the weak in-plane shear stiffness of the composite panel, which shows the effectiveness of the mode weighted summation method. The I-shaped composite beam uses the modal strain energy summation of the weight factor, and the higher modal strain energy is concentrated on the middle part of the beam and at 1/4 and 3/4 of it. Therefore, the weak part of the vibration can be clearly identified. The higher modal strain energy is extracted by the method proposed to this paper, which can be used as a reference to structural design and dynamic on-line monitoring.
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SILVA, R. L., L. M. TRAUTWEIN, C. S. BARBOSA, L. C. ALMEIDA, and G. H. SIQUEIRA. "Empirical method for structural damage location using dynamic analysis." Revista IBRACON de Estruturas e Materiais 13, no. 1 (February 2020): 19–31. http://dx.doi.org/10.1590/s1983-41952020000100003.
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Abstract This paper presents the use of numerical model techniques for identification and damage location adopting the Modal Curvature Difference (MCD) method as reference for the analysis of a simply supported concrete structure. Then, an empirical formulation to detect damages in this structure is proposed. In this method, called Acceleration Summation Difference (ASD), the difference of acceleration amplitude between intact and damaged structures are calculated for concrete plates simply supported on rubber bearings. During the analyses, the finite element models were developed using SAP2000® software. The results obtained depicted that it is possible to determine the approximate position of one or more damages in the structure, with some restrictions, and the proposed ASD method presented good correlation to localize the position of single or multiple damages.
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Dong, Chunguang, Ronghui Wang, Xiaoxia Zhen, and Haonan Ni. "Free vibration of summation and difference resonance of the vertical cable and other coupled structural members." Advances in Structural Engineering 21, no. 5 (October 6, 2017): 707–20. http://dx.doi.org/10.1177/1369433217729515.
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Free vibration of summation and difference resonance of the vertical cable and other coupled structural members were investigated in this article. A model of a vertical cable and two mass–springs was built, with the sling considered to be geometrically nonlinear, and the upper and lower connecting structural members were taken as two mass–springs. Assuming the displacement of the sling, modal superposition method and D’Alembert principle were used to derive the dynamic equilibrium equations of the coupled structure. The nonlinear dynamic equilibrium equations were studied by means of multiple scales method, and the second-order approximation solutions of single-modal motion of the system were obtained. Numerical examples were presented to discuss the amplitude responses as functions of time of free vibration, with and without damping, respectively. Additionally, fourth-order Runge–Kutta method was directly used for the nonlinear dynamic equilibrium equations to complement and verify the analytical solutions. The results show that the coupled system performs strongly nonlinear and coupled characteristics, which is useful for engineering design.
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Kaveh, A., H. Rahami, and Iman Shojaei. "An efficient method for seismic analysis of structures." Engineering Computations 32, no. 6 (August 3, 2015): 1708–21. http://dx.doi.org/10.1108/ec-07-2014-0159.
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Purpose – The purpose of this paper is to present an efficient method for dynamic analysis of structures utilizing a modal analysis with the main purpose of decreasing the computational complexity of the problem. In traditional methods, the solution of initial-value problems (IVPs) using numerical methods like finite difference method leads to step by step and time-consuming recursive solutions. Design/methodology/approach – The present method is based on converting the IVP into boundary-value problems (BVPs) and utilizing the features of the latter problems in efficient solution of the former ones. Finite difference formulation of BVPs leads to matrices with repetitive tri-diagonal and block tri-diagonal patterns wherein the eigensolution and matrix inversion are obtained using graph products rules. To get advantage of these efficient solutions for IVPs like the dynamic analysis of single DOF systems, IVPs are converted to boundary-value ones using mathematical manipulations. The obtained formulation is then generalized to the multi DOF systems by utilizing modal analysis. Findings – Applying the method to the modal analysis leads to a simple and efficient formulation. The laborious matrix inversion and eigensolution operations, of computational complexities of O(n2.373) and O(n3), respectively, are converted to a closed-form formulation with summation operations. Research limitations/implications – No limitation. Practical implications – Swift analysis has become possible. Originality/value – Suitability of solving IVPs and modal analysis using conversion and graph product rules is presented and applied to efficient seismic optimal analysis and preliminary design.
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Liu, Zhong-Sheng, Kun Wang, Cheng Huang, and Su-Huan Chen. "An extended hybrid method for contribution due to truncated lower- and higher-frequency modes in modal summation." Engineering Structures 18, no. 7 (July 1996): 558–63. http://dx.doi.org/10.1016/0141-0296(95)00123-9.
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Lee, Jongsuh. "Estimation Modal Parameter Variation with Respect to Internal Energy Variation Based on the Iwan Model." Applied Sciences 9, no. 20 (October 12, 2019): 4290. http://dx.doi.org/10.3390/app9204290.
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Typical factors that cause nonlinear behavior in structures are geometric nonlinearity, force and displacement boundary condition nonlinearities, and material nonlinearity. The nonlinearity caused by an increase of the internal energy in built-up structures is mostly due to the displacement boundary condition induced by the contact interface region. This study proposes an experimental mode analysis technique that predicts changes in natural frequencies and damping ratios when the external excitation force increases in a structure’s contact surfaces. Specifically, the nonlinearity of the dynamic characteristics induced by the contact region is described by the constitutive Iwan model. Next, an estimation method was developed for two parameters among the four of the Iwan model. This study used a modal analysis method. As an extension of a previous study, the approximate form of the harmonic excitation-induced force was determined in closed form. The configuration of the numerical model for the full structure was introduced from this resultant form. By using these numerical results, responses in the full structure, according to the harmonic excitation, have been represented in mode summation form. This research proposes an estimation method for two parameters among the four of the constitutive model. The proposed method was verified by simulations conducted with the lumped model and by experiments conducted on a partially connected double beam.
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Zhang, Tong, Ludi Kang, Xin Li, Hongbo Zhang, and Bilong Liu. "Sound Transmission Prediction of Sandwich Plates With Honeycomb and Foam Cores and an Emphatic Discussion on Radiation Terms." International Journal of Acoustics and Vibration 26, no. 1 (March 30, 2021): 70–79. http://dx.doi.org/10.20855/ijav.2020.25.11735.
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When applying the modal summation method to the sound transmission loss (STL) prediction of various plates, the assumption of the blocked sound pressure, or alternatively speaking, ignoring sound radiation terms, has obvious simplicity and is sometimes used for the single-layered panels, rib-stiffened plates or heavily damped sandwich plates. For light-weighted sandwich plates with honeycomb and foam cores, however, this assumption is somewhat in doubt and worth examining. Based on sixth-order differential equations governing the flexural vibration of sandwich plates, the prediction formula of STL is derived by the modal summation approach. Theoretical predictions were validated by measurement data. Next, the theoretical formula of STL under the assumption of the blocked sound pressure was examined. The STL discrepancies of sandwich plates caused by sound radiation terms are illustrated. It was found that the STL discrepancies of sandwich plates were closely related to frequency, reached their peak value at the coincidence frequency region. The results indicate that the sound radiation terms, or the couplings between the radiated sound pressure and the plate response, should not be ignored for the prediction of STL for sandwich plates with honeycomb and foam cores.
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Zhang, Zhiyi, Yong Chen, Hongguang Li, and Hongxing Hua. "Simulation and Experimental Study on Vibration and Sound Radiation Control with Piezoelectric Actuators." Shock and Vibration 18, no. 1-2 (2011): 343–54. http://dx.doi.org/10.1155/2011/509675.
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FEM/BEM is adopted to model the interaction between the fluid and structures. In the modeling, modal truncation and inertial coupling are applied to sufficiently reduce the coupled model order. This approach is adopted for the purpose of constructing a modal model in the time domain. Active vibration control is realized with piezoelectric actuators and an adaptive method. In the control, the summation of vibration responses is used as the control error since the integral of acceleration on the plate surface is approximately proportional to the far field sound pressure. A rigidly baffled plate connected with a mass through one piezoelectric actuator is simulated at first. In the experiment, the plate is excited by a rotating eccentric mass and controlled with four piezoelectric actuators. The results have shown that active vibration control with the piezoelectric actuators can lead to a noticeable attenuation in sound pressure.
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Shen, Runjie, Danqiong Hua, Yiying Wang, Ruimin Xing, and Min Ma. "Ultra-short-time prediction technology of wind power station output based on variational mode decomposition and particle swarm optimization least squares vector machine." E3S Web of Conferences 185 (2020): 01051. http://dx.doi.org/10.1051/e3sconf/202018501051.
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Wind power is developing rapidly in the context of sustainable development, and a series of problems such as wind curtailment and power curtailment have gradually emerged. The forecast of power generation output has become one of the hotspots of current research. This paper proposes a wind power plant output ultra-short-time prediction technology based on variational modal decomposition and particle swarm optimization least squares vector machine. Variational Modal Decomposition (VMD) method decomposes the historical output data of wind power plants at multiple levels. At the same time, it explores the impact of various decomposition methods such as EMD decomposition on the prediction accuracy, and uses the least squares support vector machine based on particle swarm optimization algorithm. Predictive summation is performed on each level of data separately to obtain a more accurate prediction effect, which has a certain improvement in prediction accuracy compared with traditional prediction algorithms.
Dissertations / Theses on the topic "Modal summation method"
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La, Mura Cristina. "Wave propagation in three-dimensional anelastic media: the modal summation method in the WKBJ-approximation." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3141.
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2007/2008In this thesis a new methodology for computing synthetic seismograms, complete of the main direct, refracted, converted phases and surface waves, in three – dimensional anelastic lateral heterogeneous media is presented. It is based on the combination of the Modal Summation technique with the Asymptotic Ray Theory. The three – dimensional models are determined by a set of vertically heterogeneous sections (1D structures) that are juxtaposed on a regular grid. The distribution of these sections in the grid is done in such a way to satisfy the condition of applicability of the WKBJ – approximation, i.e. the lateral variation of all the elastic parameters has to be small with respect to the prevailing wavelength. In each knot of the grid a vertically heterogeneous section is located, hence, the values of the phase velocities, of the phase attenuation and of the group velocities are assigned once and for all. Inside the grid the source and the receiver are located, assigning their coordinates by means of a Cartesian reference system introduced in the grid itself. By this way a vertically heterogeneous structure, hence one-dimensional structure, is associated to the source and another to the receiver. The eigenfunctions of these two structures do contribute to the seismogram. The computational scheme is based, besides on the WKBJ - approximation for weak lateral heterogeneities, on the two point ray – tracing algorithm, by means of the bi - dimensional shooting method. It can be summarized as follows: at first the ray connecting two points, the source and the receiver, is computed solving the Cauchy problem for the system of ordinary differential equations governing the phenomenon of the evolution of the ray itself; the system is solved employing the numerical fourth – order Runge – Kutta method. Once the ray is determined, the attenuation is computed along it, solving, once again using the fourth – order Runge – Kutta method, the Cauchy problem for a system of ordinary differential equations that is made up of four equations: three equations for the ray and one equation governing the evolution of the attenuation along the ray itself. Finally, the geometrical spreading is computed considering two more rays that leave the source with an azimuth that is determined increasing and decreasing the azimuth of the characteristic curve of the ray – tracing system (the true ray) by a fixed quantity. The thesis is divided in two main parts, the first contains a theoretical treatment of the above mentioned arguments, so it opens with a brief summary about the generation of synthetic seismograms in one-dimensional structures by mean of the Modal Summation technique and goes on with the introduction of the WKBJ – approximation for treating the lateral heterogeneities. Then, there is the presentation of the numerical procedure used in this work. The second part is devoted to the validation of the new method, so the simulations executed to this aim are shown. It is very important to stress that the computational codes used in this work are still under development. They will be used for verifying and optimizing the results up to now obtained, both in terms of seismic sources and in terms of structural models, in region of the Scotia Arc.
In questa tesi si presenta una nuova metodologia per il calcolo di sismogrammi sintetici completi delle principali fasi dirette, rifratte, convertite ed onde superficiali in mezzi tridimensionali anelastici lateralmente eterogenei, basata sulla Somma Modale (SM) combinata con la Teoria Asintotica dei Raggi (TAR). I modelli tridimensionali sono determinati da un insieme di sezioni verticalmente eterogenee (strutture 1D) che vengono affiancate su una griglia regolare. La distribuzione di dette sezioni nella griglia e’ tale da soddisfare la condizione di applicabilità della approssimazione WKBJ (acronimo dei nomi dei quattro elaboratori della metodologia: Wentzel, Kramers, Brillouin and Jeffreys), cioè la variazione laterale di tutti i parametri elastici deve essere piccola rispetto alle lunghezze d’onda prevalenti. In ogni nodo della griglia e’ collocata una sezione verticalmente eterogenea, sono, quindi, assegnati una volta per tutte i valori della velocità di fase, dell’attenuazione di fase e della velocità di gruppo. All’interno della griglia si collocano la sorgente ed il ricevitore, assegnando le loro coordinate attraverso un sistema cartesiano di riferimento introdotto nella griglia stessa. In questo modo si associa una struttura verticalmente eterogenea, quindi unidimensionale, alla sorgente ed una al ricevitore. Le autofunzioni di queste due strutture contribuiscono al sismogramma. Lo schema computazionale è basato, oltre che sull’approssimazione WKBJ per eterogeneità laterali deboli, sull’algoritmo per il ray-tracing tra due punti, mediante lo shooting-method bidimensionale. Esso può essere riassunto come segue: dapprima si calcola il raggio che unisce i due punti, la sorgente ed il ricevitore, risolvendo il problema di Cauchy per il sistema di equazioni differenziali alle derivate ordinarie che governa il fenomeno dell’evoluzione del raggio stesso; il sistema è risolto per via numerica mediante il metodo di Runge-Kutta del quarto ordine. Una volta che il raggio è determinato, si calcola lungo esso l’attenuazione, risolvendo, ancora una volta mediante il metodo di Runge-Kutta del quarto ordine, il problema di Cauchy per un sistema di equazioni differenziali alle derivate ordinarie che è costituito dal sistema che governa l’evoluzione del raggio più una quarta equazione che governa l’evoluzione dell’attenuazione lungo il raggio stesso. Infine, il geometrical spreading è calcolato considerando due ulteriori raggi che partono dalla sorgente con un azimuth 5 che è determinato aumentando e diminuendo l’azimuth della curva caratteristica del sistema (raggio vero) di un valore fissato. La tesi è divisa in due parti principali, la prima parte contiene una trattazione teorica degli argomenti precedentemente menzionati, si apre quindi con un breve riassunto sulla generazione di sismogrammi sintetici in strutture unidimensionali mediante la tecnica della Somma Modale e prosegue con l’introduzione dell’approssimazione WKBJ per la trattazione delle eterogeneità laterali. Si passa poi alla presentazione della procedura numerica utilizzata. La seconda parte è dedicata alla validazione del nuovo metodo, dunque sono presentate le simulazioni eseguite a questo scopo. E’ da sottolineare che i codici di calcolo utilizzati, attentamente testati e ripetutamente validati, sono in continuo sviluppo. Essi verranno utilizzati per la verifica e l’ottimizzazione dei risultati fin qui conseguiti, sia in termini di sorgenti sismiche che di modelli strutturali, nella regione dell’Arco di Scotia.
XXI Ciclo
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SOARES, ALBERTO. "A MODEL POWER FLOWS BASED ON THE POWER SUMMATION METHOD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1992. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8982@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEste trabalho apresenta uma metodologia para o cálculo de Fluxo de Potência em redes radiais através do Método de Soma de Potências, que explora as características dos parâmetros da rede bem como a sua topologia, constituindo- se em um método bastante rápido e robusto. Propõe-se também uma nova metodologia para o controle de tensão na rede através de rotinas de sensibilidade visando a efetuação de manobras ou cortes de carga na rede. São apresentados testes com sistemas realistas.
This work presents a methodology for radial power flows based on the power Summation Method, able to exploit the network particular characteristics in order to achieve accuracy and efficiency. This work also presents a novel model for radial network control based on sensitivity coefficients that evaluate load transfer or curtailment effects on network performance. Some tests with realistic systems are presented.
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Rizzi, Leandro Gutierrez. "Simulações numéricas de Monte Carlo aplicadas no estudo das transições de fase do modelo de Ising dipolar bidimensional." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-23052009-134513/.
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O modelo de Ising dipolar bidimensional inclui, além da interação ferromagnética entre os primeiros vizinhos, interações de longo alcance entre os momentos de dipolo magnético dos spins. A presença da interação dipolar muda completamente o sistema, apresentando um rico diagrama de fase, cujas características têm originado inúmeros estudos na literatura. Além disso, a possibilidade de explicar fenômenos observados em filmes magnéticos ultrafinos, os quais possuem diversas aplicações em àreas tecnológicas, também motiva o estudo deste modelo. O estado fundamental ferromagnético do modelo de Ising puro é alterado para uma série de fases do tipo faixas, as quais consistem em domínios ferromagnéticos de largura $h$ com magnetizações opostas. A largura das faixas depende da razao $\\delta$ das intensidades dos acoplamentos ferromagnético e dipolar. Através de simulações de Monte Carlo e técnicas de repesagem em histogramas múltiplos identificamos as temperaturas críticas de tamanho finito para as transições de fase quando $\\delta=2$, o que corresponde a $h=2$. Calculamos o calor específico e a susceptibilidade do parâmetro de ordem, no intervalo de temperaturas onde as transições são observadas, para diferentes tamanhos de rede. As técnicas de repesagem permitem-nos explorar e identificar máximos distintos nessas funções da temperatura e, desse modo, estimar as temperaturas críticas de tamanho finito com grande precisão. Apresentamos evidências numéricas da existência de uma fase nemática de Ising para tamanhos grandes de rede. Em nossas simulações, observamos esta fase para tamanhos de rede a partir de $L=48$. Para verificar o quanto a interação dipolar de longo alcance afeta as estimativas físicas, nós calculamos o tempo de autocorrelação integrado nas séries temporais da energia. Inferimos daí quão severo é o critical slowing down (decaimento lento crítico) para esse sistema próximo às transições de fase termodinâmicas. Os resultados obtidos utilizando um algoritmo de atualização local foram comparados com os resultados obtidos utilizando o algoritmo multicanônico.Two-dimensional spin model with nearest-neighbor ferromagnetic interaction and long-range dipolar interactions exhibit a rich phase diagram, whose characteristics have been exploited by several studies in the recent literature. Furthermore, the possibility of explain observed phenomena in ultrathin magnetic films, which have many technological applications, also motivates the study of this model. The presence of dipolar interaction term changes the ferromagnetic ground state expected for the pure Ising model to a series of striped phases, which consist of ferromagnetic domains of width $h$ with opposite magnetization. The width of the stripes depends on the ratio $\\delta$ of the ferromagnetic and dipolar couplings. Monte Carlo simulations and reweighting multiple histograms techniques allow us to identify the finite-size critical temperatures of the phase transitions when $\\delta=2$, which corresponds to $h=2$. We calculate, for different lattice sizes, the specific heat and susceptibility of the order parameter around the transition temperatures by means of reweighting techniques. This allows us to identify in these observables, as functions of temperature, the distinct maxima and thereby to estimate the finite-size critical temperatures with high precision. We present numerical evidence of the existence of a Ising nematic phase for large lattice sizes. Our results show that simulations need to be performed for lattice sizes at least as large as $L=48$ to clearly observe the Ising nematic phase. To access how the long-range dipolar interaction may affect physical estimates we also evaluate the integrated autocorrelation time in energy time series. This allows us to infer how severe is the critical slowing down for this system with long-range interaction and nearby thermodynamic phase transitions. The results obtained using a local update algorithm are compared with results obtained using the multicanonical algorithm.
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Wirnsberger, Peter. "Computer simulation and theoretical prediction of thermally induced polarisation." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/282988.
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In this thesis, we study the phenomenon of thermally induced polarisation using a combination of theory and computer simulation. Molecules of sufficiently low symmetry exhibit thermo-molecular orientation when subjected to a temperature gradient, leading to considerable electrostatic fields in polar liquids. Here, we first use non-equilibrium molecular dynamics simulations to study this interesting effect numerically. To this end, we propose an integration algorithm to impose a constant heat flux in simulations and show that it greatly improves energy conservation compared to a previous algorithm. We next investigate the thermal polarisation of water and find that truncation of electrostatic interactions can lead to severe artefacts, such as the wrong sign of polarisation and an overestimation of the electric field. We further show that the quadrupole-moment contribution to the electric field is significant and responsible for an inversion of its sign. To facilitate the theoretical description of electrostatic interactions, we propose a new dipolar model fluid as a perturbation of a Stockmayer fluid. Using this modified Stockmayer model, we provide numerical evidence for the recently proposed phenomenon of thermally induced monopoles. We show that the electrostatic field generated by a pair of heated/cooled colloidal particles immersed in such a solvent can be trivially described by two Coulomb charges. Finally, we propose a mean-field theory to predict the thermo-polarisation effect exhibited by our model fluid theoretically, and demonstrate near quantitative agreement with simulation results.
Book chapters on the topic "Modal summation method"
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Mills, R. W., M. F. James, and D. R. Weaver. "Study of the Delayed Neutron Yield and its Time Dependence by the Summation Method, and the Sensitivity of the Yield to Parameters of the Independent Yield Model and the Decay Data." In Nuclear Data for Science and Technology, 86–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-58113-7_24.
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"Solving X-ray Crystal Structures." In Pharmaceutical Crystallography: A Guide to Structure and Analysis, 194–213. The Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/bk9781782629665-00194.
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Solving a crystal structure means generating an image of the electron density from the measured structure factors. This reverses the process described for generating an X-ray diffraction pattern from a crystal structure. The required mathematics—the Fourier summation—is well defined, but it is necessary to know both the amplitude and phase of each structure factor. The experimental measurement yields the diffracted intensities, from which only the structure factor amplitudes can be extracted. Solving the structure means recovering the lost phase information. For most small-molecule pharmaceutical analyses, structure solution is achieved by direct methods or dual-space methods, both of which are automated and highly effective. If a partial structure is obtained, it can be developed by a Fourier summation using the measured structure factor amplitudes and the phases calculated from the current structure model. The resulting image of the electron density should reveal new atoms that can be added to the model, then the process can be iterated until it converges on the complete structure.
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Alzahrani, Sahar Matar. "A Framework for the Assessment of Learner Autonomy in Language Learning." In ICT-Based Assessment, Methods, and Programs in Tertiary Education, 1–22. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-3062-7.ch001.
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This research reports on the assessment of the improvement in the language learner autonomy (LLA) of a group of Saudi medicine students at tertiary level following an intervention that aims to examine and enhance their LLA in a blended course. Thus, this study proposes a research model for the assessment of LLA in the 21st century and establishes a scale for its measurement. Because LLA is a combination of observable and non-observable behaviors, quantitative and qualitative methods were triangulated in a mixed method research to look at it through the learner voice and metacognition (process perspective) and through the learner gained test scores (product perspective). To overcome the problem that LLA is an unsteady state, the assessment model integrates summative and formative assessment methods. Findings show that the assessment of LLA helps to better understand the process of LLA enhancement and the potential factors that might influence learners' LLA.
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Riascos, Roberto, Tomislava Majić, Egon Ostrosi, Jean-Claude Sagot, and Josip Stjepandić. "Functional Approach for Summative Risk Management of Medical Products." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210138.
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In the search to maintain the integrity of all systems and components over the span of the product’s life, a tightly integrated risk management process and system shall enable a discrete but frequent enough calculation method. The challenge is finding a methodology where risk management is living, concomitant process throughout the lifecycle, which is cumulative, so the risk assessments refine with the product’s definition while adhering to a tightly regulated enviroment for medical devices. This process needs be fully embedded in the PLM processes so it is able to accompany the product at any change throughout its life. The Multi-interfaces Entity Model (MIEM) was introduced integrated with a summative risk management concept that allows an incremental risk analysis, while the entities in the MIEM are refined. The results were a recursive methodology that supported with a PLM integrated risk management, can be automated to make sure the risk assessment is complete, re-usable and configurable as an additional PLM function. The focus of this paper lies on the generation of the functional structure of a product which is connected with the Multi-interfaces Entity Model. This allows to create a configured design structure, applying recursively the same cumulative properties of the risk assessment where a new configuration would create new interfaces.
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Stevens, Helena, and Tracy Peed. "Culturally Responsive Program Evaluations." In Research Anthology on Culturally Responsive Teaching and Learning, 254–75. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-9026-3.ch016.
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Program evaluations in education programs are conducted to address the outcomes, experiences, and phenomena that occur from programs. Program evaluation models are plentiful, and commonly used models include objectives, summative, formative, process, and outcome approaches. The strength of the model relies on the competencies and confidence of the evaluators. When used properly models are a reliable method for judging programs and their outcomes. Absent from these models is the intentional inclusion of culture. Culture is multidimensional and intersectional and holistically affects programs. Therefore, as the cultural makeup of the education systems continues to grow in diversity, program evaluation models must consider the impacts and influences that multi-dimensional culture has on programs at all stages of planning, delivery, and evaluation. This chapter provides specific areas of cultural identity to address with explicit steps for infusing deliberate emphasis into the program evaluation models.
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Stevens, Helena, and Tracy Peed. "Culturally Responsive Program Evaluations." In Implementing Culturally Responsive Practices in Education, 16–37. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-3331-4.ch002.
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Program evaluations in education programs are conducted to address the outcomes, experiences, and phenomena that occur from programs. Program evaluation models are plentiful, and commonly used models include objectives, summative, formative, process, and outcome approaches. The strength of the model relies on the competencies and confidence of the evaluators. When used properly models are a reliable method for judging programs and their outcomes. Absent from these models is the intentional inclusion of culture. Culture is multidimensional and intersectional and holistically affects programs. Therefore, as the cultural makeup of the education systems continues to grow in diversity, program evaluation models must consider the impacts and influences that multi-dimensional culture has on programs at all stages of planning, delivery, and evaluation. This chapter provides specific areas of cultural identity to address with explicit steps for infusing deliberate emphasis into the program evaluation models.
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Saito, Ken, Minami Takato, Yoshifumi Sekine, and Fumio Uchikoba. "Silicon Micro-Robot With Neural Networks." In Rapid Automation, 979–90. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-8060-7.ch045.
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Insect type 4.0, 2.7, 2.5 mm. width, length, height size silicon micro-robot system with active hardware neural networks locomotion controlling system is presented in this chapter. The micro-robot system was made from a silicon wafer fabricated by Micro-Electro Mechanical Systems (MEMS) technology. The mechanical system of the robot equipped with millimeter-size rotary type actuators, link mechanisms, and six legs to realize the insect-like switching behavior. In addition, the authors constructed the active hardware neural networks by analog CMOS circuits as a locomotion controlling system. Hardware neural networks consisted of pulse-type hardware neuron models as basic components. Pulse-type hardware neuron model has same basic features of biological neurons such as threshold, refractory period, spatio-temporal summation characteristics, and enables the generation of continuous action potentials. The hardware neural networks output the driving pulses using synchronization phenomena such as biological neural networks. Four output signal ports are extracted from hardware neural networks, and they are connected to the actuators. The driving pulses can operate the actuators of silicon micro-robot directly. Therefore, the hardware neural networks realize the robot control without using any software programs or A/D converters. The micro-robot emulates the locomotion method and the neural networks of an insect with rotary type actuators, link mechanisms, and hardware neural networks. The micro-robot performs forward and backward locomotion, and also changes direction by inputting an external trigger pulse. The locomotion speed was 26.4 mm/min when the step width was 0.88 mm.
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Saito, Ken, Minami Takato, Yoshifumi Sekine, and Fumio Uchikoba. "Silicon Micro-Robot with Neural Networks." In Engineering Creative Design in Robotics and Mechatronics, 1–10. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4225-6.ch001.
Full textAbstract:
Insect type 4.0, 2.7, 2.5 mm. width, length, height size silicon micro-robot system with active hardware neural networks locomotion controlling system is presented in this chapter. The micro-robot system was made from a silicon wafer fabricated by Micro-Electro Mechanical Systems (MEMS) technology. The mechanical system of the robot equipped with millimeter-size rotary type actuators, link mechanisms, and six legs to realize the insect-like switching behavior. In addition, the authors constructed the active hardware neural networks by analog CMOS circuits as a locomotion controlling system. Hardware neural networks consisted of pulse-type hardware neuron models as basic components. Pulse-type hardware neuron model has same basic features of biological neurons such as threshold, refractory period, spatio-temporal summation characteristics, and enables the generation of continuous action potentials. The hardware neural networks output the driving pulses using synchronization phenomena such as biological neural networks. Four output signal ports are extracted from hardware neural networks, and they are connected to the actuators. The driving pulses can operate the actuators of silicon micro-robot directly. Therefore, the hardware neural networks realize the robot control without using any software programs or A/D converters. The micro-robot emulates the locomotion method and the neural networks of an insect with rotary type actuators, link mechanisms, and hardware neural networks. The micro-robot performs forward and backward locomotion, and also changes direction by inputting an external trigger pulse. The locomotion speed was 26.4 mm/min when the step width was 0.88 mm.
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Kennedy, Carol Kahan, and Tina Yagjian. "Creating an Early Model of Teaching at The New School." In Critical Examinations of Distance Education Transformation across Disciplines, 15–43. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-6555-2.ch002.
Full textAbstract:
In 1998, the AT&T Foundation awarded a grant to the Teacher Education Graduate Program at The New School, a university in New York City, to implement an Advanced Professional Certificate (APC) in Teaching and Learning with Technology (TELT). The grant was given to train public secondary classroom teachers in urban schools how to integrate technology into their classes. Using a cognitive science and constructivist-based theoretical framework, a twelve-credit four-course curriculum to earn the APC was developed. The intention was to offer it in a blended format in Fall 2000 through DIAL (Distance Instruction for Adult Learners), the New School's innovative online learning program. Because this was occurring during the early days of computer use in the classroom, many faculty and students had no prior experience in teaching and learning with technology, much less with teaching and learning over the internet. Web-based learning was in its infancy. DIAL was one of the first online learning programs in the United States to offer degrees, certificates and courses in the liberal arts through a computer-mediated environment. The Advanced Placement Certificate in Teaching and Learning with Technology was the first of its kind to offer a theoretically-based course curriculum in a blended learning format to urban educators. The historically significant outcomes were as follows: creating a method for teaching instructors how to teach technology online, learning how to integrate technology in the classroom, learning how to teach as well as participate in an online environment, using the DIAL interface which was an early platform built, in part, on a customized Linux platform. The pilot TELT program used both formative and summative assessments for learning outcomes and efficacy. The results were positive and a model for teacher education with technology was created. Nothing of this kind existed previously. The model was for continuing the New School graduate certificate program in the next stage.
Conference papers on the topic "Modal summation method"
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Sung, Shung H., and Donald J. Nefske. "Overview of Structural-Acoustic Modal Analysis Under Random Loading." In ASME 2018 Noise Control and Acoustics Division Session presented at INTERNOISE 2018. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ncad2018-6130.
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Random excitations can result from various types of non-deterministic loads such as wind loads, terrain loads, and other types of white noise loads. In this paper, an overview is presented of the modal method to obtain the random response of a coupled structural-acoustic system subjected to random excitations. When the structural system is coupled with an enclosed cavity, the structural-acoustic frequency response functions (FRFs) can be obtained using the uncoupled structural modes and the uncoupled acoustic modes, with structural-acoustic coupling as well as modal damping included in the formulation. The random response of the coupled structural-acoustic system is then obtained by summation of the structural-acoustic FRFs with the applied auto- and cross-spectral random loadings at the excitation locations. The theoretical formulation of the coupled structural-acoustic system is described. An example of a rectangular cavity coupled with flexible panels exposed to external random white noise load is presented. The methodology is then applied to an automotive vehicle travelling over a randomly rough road to predict the interior sound pressure response in the vehicle.
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Li, Hua, and Kaiming Hu. "Fuzzy Controller for Active Vibration Control of Cylindrical Shells." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-72140.
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Cylindrical shells are widely used engineering structures, such as pipelines, tubes, submarine shells, etc. The active vibration control of these structures are important methods for ensuring their performance. In this paper, a fuzzy logic controller was proposed for the active vibration control of cylindrical shells. Piezoelectric actuators were laminated on the shell surface for the generation of control force. Then, the mathematical model of the model control force were given based the inverse piezoelectric effects and modal summation method. The transfer equation of the controlled system was derived from the modal equation. The fuzzy logic controller was then designed, in which the centroid method was used for defuzification. The proposed controller was then implemented in Matlab/Simulink environment, followed by case studies to evaluate its performance. Numerical results shown the effectiveness of fuzzy logic controller on active vibration of smart cylindrical shells. For all evaluated cases, more than 33% of amplitude reduction were achieved.
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Belibassakis, K. A., and G. A. Athanassoulis. "A Coupled-Mode Method for Acoustic Propagation and Scattering in Inhomogeneous Ocean Waveguides." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23317.
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We consider the problem of acoustic propagation and scattering in inhomogeneous waveguide governed by the Helmholtz equation. We focus on an ideal, cylindrically symmetric ocean waveguide, limited above by an acoustically soft boundary modelling the free surface, and below by a hard boundary modelling the impenetrable seabed with general bottom topography. The wave field is excited by a monochromatic point source, and thus, the present solution is equivalent to the construction of the Green’s function in the inhomogeneous domain. An improved coupled-mode method is developed, based on an enhanced local-mode series for the representation of the acoustic field, which includes an additional mode accounting for the effects of the bottom slope and curvature. The additional mode provides an implicit summation of the slowly convergent part of the series, rendering the remaining part to converge much faster, pemitting truncation of the modal expansions keeping only a few evanescent terms. Using the enhanced representation, in conjunction with an appropriate variational principle, a system of coupled-mode equations on the horizontal plane is derived for the determination of the complex modal-amplitude functions. Numerical results are presented including comparisons with analytical solutions illustrating the role and significance of the additional mode and the efficiency of the present coupled-mode tmodel, which can be naturally extended to treat propagation and scattering problems in three-dimensional, multi-layered ocean acoustic waveguides.
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Harata, Yuji, and Takashi Ikeda. "Modal Analysis to Interpret Localization Phenomena in Two Nonlinear Tuned Mass Dampers." In ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-69248.
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Abstract This study investigates localization phenomena in two identical nonlinear tuned mass dampers (TMDs) installed on an elastic structure, which is subjected to external, harmonic excitation. In the theoretical analysis, the mode shapes of the system are determined, and the modal equations of motion are derived using modal analysis. These equations are demonstrated as forming an autoparametric system in which external excitation directly acts on the first and third vibration modes, whereas the second vibration mode is indirectly excited due to the nonlinear coupling with the other modes. Van der Pol’s method is employed to obtain the frequency response curves for both physical and modal coordinates. The two TMDs vibrate in phase for the first and third modes, but vibrate out of phase for the second mode. Consequently, when all modes appear, the two TMDs may vibrate at different amplitudes, i.e., localization phenomena may occur because the TMD motions are expressed by the summation of motions for all modes. The numerical calculations clarify that the localization phenomena may occur in the two TMDs when all three modes appear simultaneously. Moreover, there are two steady-state solutions of the harmonic oscillations for the second mode with identical amplitudes; however, their phases differ by π. Hence, which TMD vibrates at higher amplitudes depends on which of these two steady-state solutions for the phase.
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Beck, Joseph A., Jeffrey M. Brown, Charles J. Cross, and Joseph C. Slater. "Probabilistic Mistuning Assessment Using Nominal and Geometry Based Mistuning Methods." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68533.
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Two deterministic mistuning models utilizing component mode synthesis methods are used in a Monte Carlo simulation to generate mistuned response distributions for a geometrically perturbed Integrally Bladed Rotor. The first method, a frequency-perturbation approach with a nominal mode approximation used widely in academia and industry, assumes airfoil geometric perturbations alter only the corresponding modal stiffnesses while its mode shapes remain unaffected. The mistuned response is then predicted by a summation of the nominal modes. The second method, a geometric method utilizing non-nominal modes, makes no simplifying assumptions of the dynamic response due to airfoil geometric perturbations, but requires recalculation of each airfoil eigen-problem. A comparison of the statistical moments of the mistuned response distributions and prediction error is given for three different frequency ranges and engine order excitations. Further, the response distributions are used for a variety of design and testing scenarios to highlight impacts of the frequency-based approach inaccuracy. Results indicate the frequency-based method typically provides conservative response levels.
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Bogard, F., K. Debray, Y. Q. Guo, and A. Pavan. "Determination of Optimum Sensor Positions for Defect Detection on Revolving Machines by a Finite Element Vibration Analysis." In ASME 2000 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/detc2000/dac-14506.
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Abstract The vibration monitoring is largely used to detect the defects in the revolving machines. The determination of the best sensor positions is one of main research goals in the domain of the conditional maintenance. This paper proposes a numerical methodology based on a finite element model and a spectral analysis in order to find optimum sensor positions. The bearing is considered as a key component in vibration propagation from the moving parts to static ones. In this paper, we use an analytical bearing model and its numerical implementation in a FE code. The tangent stiffness matrix of the bearing element is calculated by the Newton-Raphson method and then introduced into the modal and spectral analysis. The technique of “Mode Shape Summation Plot” (MSSP) is adopted to find the most sensitive zones to usual defects. The proposed numerical approach gives good agreements with the experimental results. A real grinder modeling shows its interesting industrial applications.
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Li, H., Z. B. Chen, S. D. HU, and H. S. Tzou. "Optimal Control of Clamped-Free Conical Shell Using Diagonal Piezoelectric Sensor and Actuator." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63028.
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In this paper, optimal vibration control of a clamped-free conical shell is presented. A diagonal piezoelectric sensor/actuator (S/A) pair is proposed to control the axial, bending and transverse vibrations of the conical shell. The modal functions are adapted to satisfy the clamped-free boundary condition. Based on the independent modal control method, the response of conical shell to external excitations can be represented by the summation of all participating natural modes and their respective modal participation factors and each mode can be controlled independently. The modal equation is transformed into the linear state space form. The modal participation factor and its time derivative are chosen to be the state variables. The sensing signals are chosen to be the output vector. The modal force is chosen to be the control input vector. The linear quadratic (LQ) controllers are designed for each independent mode. The optimal gain matrix is related to the ratio between control voltage and sensing signal by the modal control force per unit voltage and the sensing signal. Numerical examples show that, the proposed optimal control method can achieve significant active control effects and the optimal gains are mainly related to the modal velocity. This effect varies with the locations of S/A pair and the mode of the shell. The results indicate that, to achieve the best control effects for all wanted modes, the optimal controller and the optimization of the S/A location should be taken into account in the design of the optimal controller.
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Tan, Zhimin, Yucheng Hou, John Zhang, and Terry Sheldrake. "Irregular Wave Simulation and Fatigue Damage Evaluation of a Flexible Riser Subjected to Bi-Modal Sea States." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83386.
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This paper presents the fatigue evaluation of a flexible riser subjected to bi-modal sea states, where the local wind and swell conditions act simultaneously, and is observed in many offshore regions including Brazil and West Africa. Due to the irregularity of the riser responses, the traditional, regular wave approach for assessing the fatigue damage of a flexible pipe cannot be applied without significant simplifications. A typical deviation would be to treat the combined swell and wind conditions at sea as two sets of separate cases. The regular wave approach can then be applied and the summation of the damage of both cases defined as the final damage of the pipe. As an alternative, this paper presents a more theoretically accurate irregular wave approach. The entire irregular wave simulation was first performed using the commercial software, OrcaFlex™, together with a tensile wire stress model developed in-house. The model implements the pipe bending hysteresis behavior during dynamic excitation, producing corresponding time history stress results, which are used to assess the fatigue damage using a rain-flow counting method. Two case studies are presented, the first being a dynamic simulation performed with two wave trains generated based respectively on the given swell and wind sea spectrums. In the second case study, a single wave train is generated based on the combined spectrum of the swell and wind sea states. Both results are compared with those obtained by the traditional regular wave approach and a preferred analysis method is recommended based on the conservatism and time efficiency.
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Wu, Shanyue, Yingyun Huang, and Shijian Zhu. "Study on Air Spring’s Finite Element Model." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48364.
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In order to analyze air spring’s characteristic numerically, multi-step method is presented to establish its finite element model. In the model, air spring’s rubber bladder is described with approximation method, and the inside volume is calculated by means of discrete summation. The actual analysis results show that the model is practical.
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Lee, Chan Hui, Keun Bok Song, and Heui Won Kim. "Vibration Analysis and Evaluation for the Offshore Structure Using Simplified Model and RSS Method." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-84053.
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The evaluation of the vibration characteristics of offshore structure in the design stage is important to ensure the safety of structure, equipment and worker. Conventionally, the vibration analysis of the offshore structure is carried out according to its own analysis procedure including the selection of vibrating equipment, FE modeling, evaluation of excitation forces and criteria. The efficient modeling of the vibration equipment and the consideration of the phase of excitation forces are necessary to reduce the calculation time and to increase the accuracy of analysis. In this paper, the efficient and accurate vibration analysis method is introduced including the simplified model of equipment and the RSS (root squared summation) method. The vibration equipment was modeled as the simplified model of which mesh size is reduced by 90%, however, its vibration characteristics such as natural frequency and vibration modes are not changed. In addition, the RSS method was applied in the forced vibration analysis to consider appropriate phase of excitation forces. As the RSS method is the summation of all the vibration response with respect to each excitation forces, it presents more reasonable and conservative vibration evaluation. The proposed vibration analysis method has been confirmed by conducting various offshore projects and is expected to be more efficient for the design of offshore structure.