31,253 results on '"Nonlinear analysis"'
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2. Seismic analysis and design of multi-tiered steel eccentrically braced frames with built-up tubular links
- Author
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Ashrafi, Abolfazl and Imanpour, Ali
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- 2025
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Catalog
3. Structural performance and design of assembled aluminum alloy-concrete-carbon steel double-skin tubular column
- Author
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Xu, Wengang, Zhang, Jigang, Yan, Qingfeng, Li, Wei, Song, Zhenhui, Yu, Fengbo, Niu, Yun, and Song, Hanyu
- Published
- 2025
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4. Seismic force modification factors for wood light-frame buildings incorporating a new type of OSB-sheathed Midply shear wall system
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Kari, Amir, Lam, Frank, and Li, Minghao
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- 2025
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5. Experimental validation of a simplified structural design for lattice transmission towers
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Kim, Pyounghwa, Han, Whi Seok, Kim, Heesoo, Kim, Jeong Hun, Kang, Young Jong, and Kim, Seungjun
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- 2025
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6. Earthquake-induced loss assessment of steel moment-resisting knee-braced frame buildings in southwestern Canada
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Mokhtari, Mahdi, Moammer, Omid, and Imanpour, Ali
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- 2025
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7. New energy-based methodology to characterize nonlinear seismic response
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Tropea, Giulio Augusto, Angelucci, Giulia, Bernardini, Davide, Quaranta, Giuseppe, and Mollaioli, Fabrizio
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- 2025
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8. Comprehensive review of the structural behaviour and numerical modelling of recycled aggregate concrete-filled steel tubes
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Nikolić, Jelena, Tošić, Nikola, Murcia-Delso, Juan, and Kostić, Svetlana M.
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- 2024
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9. Strengthening of unreinforced masonry buildings with ferrocement composite overlay: Material characterization and numerical study
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Mukherjee, Anubhab and Kaushik, Hemant B.
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- 2025
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10. Structural behaviour of tunnels exposed to fire using numerical modelling strategies
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Díaz, Rafael Sanabria, Lantsoght, Eva, and Hendriks, Max A.N.
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- 2025
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11. Harnessing complexity: Nonlinear optical phenomena in L-shapes, nanocrescents, and split-ring resonators.
- Author
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Clark, Michael R., Shah, Syed A., Piryatinski, Andrei, and Sukharev, Maxim
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SECOND harmonic generation , *OPTICAL properties , *NANOPARTICLES , *NONLINEAR analysis , *MOLECULAR spectra - Abstract
We conduct systematic studies of the optical characteristics of plasmonic nanoparticles that exhibit C2v symmetry. In particular, we analyze three distinct geometric configurations: an L-type shape, a crescent, and a split-ring resonator shaped like the Greek letter π. Optical properties are examined using the finite-difference time-domain method. It is demonstrated that all three shapes exhibit two prominent plasmon modes associated with the two axes of symmetry. This is in addition to a wide range of resonances observed at high frequencies corresponding to quadrupole modes and peaks due to sharp corners. Next, to facilitate nonlinear analysis, we employ a semiclassical hydrodynamic model, where the electron pressure term is explicitly accounted for. This model goes beyond the standard Drude description and enables capturing nonlocal and nonlinear effects. Employing this model enables us to rigorously examine the second-order angular resolved nonlinear optical response of these nanoparticles in each of the three configurations. Two pumping regimes are considered, namely, continuous wave (CW) and pulsed excitations. For CW pumping, we explore the properties of the second harmonic generation (SHG). Polarization and angle-resolved SHG spectra are obtained, revealing strong dependence on the nanoparticle geometry and incident wave polarization. The C2v symmetry is shown to play a key role in determining the polarization states and selection rules of the SHG signal. For pulsed excitations, we discuss the phenomenon of broadband terahertz (THz) generation induced by the difference-frequency generation. It is shown that the THz emission spectra exhibit unique features attributed to the plasmonic resonances and symmetry of the nanoparticles. The polarization of the generated THz waves is also examined, revealing interesting patterns tied to the nanoparticle geometry. To gain deeper insight, we propose an analytical theory that agrees very well with the numerical experiments. The theory shows that the physical origin of the THz radiation is the mixing of various frequency components of the fundamental pulse by the second-order nonlinear susceptibility. An expression for the far-field THz intensity is derived in terms of the incident pulse parameters and the nonlinear response tensor of the nanoparticle. The results presented in this work offer new insights into the linear and nonlinear optical properties of nanoparticles with C2v symmetry. The demonstrated strong SHG response and efficient broadband THz generation hold great promise for applications in nonlinear spectroscopy, nanophotonics, and optoelectronics. The proposed theoretical framework also provides a valuable tool for understanding and predicting the nonlinear behavior of other related nanostructures. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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12. Seismic performance of buildings supported by a shallow doubly-curved shell raft foundation
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Sabermahany, Hadi and Attarnejad, Reza
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- 2022
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13. Control of buckling behavior in origami-based auxetic structures by functionally graded thickness.
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Tomita, S., Shimanuki, K., and Umemoto, K.
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POISSON'S ratio , *UNIFORM spaces , *DYNAMIC loads , *NONLINEAR analysis - Abstract
Negative Poisson's ratio in auxetic structures plays a crucial role in energy absorption and impact mitigation. Origami-based lattices within the realm of auxetic structures offer the advantage of facile fabrication and design. Nevertheless, the utilization of periodic lattices in origami-based auxetic structures constrains the available design space for achieving diverse mechanical properties. Addressing this limitation, our study introduces origami-based auxetic structures with functionally graded thickness, utilizing origami-based lattices known as Tachi–Miura polyhedra. We investigated the impact of functionally graded thickness on buckling behavior and force responses through dynamic loading experiments employing 3D-printed test pieces. The experimental results indicate that functionally graded thickness induces partial auxetic deformation in lattices, and the resulting nonsymmetric deformation prevents global buckling, thereby averting bounded forces observed in structures with uniform thickness. These findings extend the applicability of auxetic structures, spanning from energy absorption to the design of cushioning structures. [ABSTRACT FROM AUTHOR] more...
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- 2024
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14. A Revolutionary Deep Generative Modelling for Linear and Nonlinear Analysis of Masonry
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Adaileh, Ahmad, Ghiassi, Bahman, Briganti, Riccardo, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Cui, Zhen-Dong, Series Editor, Lu, Xinzheng, Series Editor, Milani, Gabriele, editor, and Ghiassi, Bahman, editor more...
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- 2025
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15. Nonparametric Local Projections.
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Gonçalves, Sílvia, María Herrera, Ana, Kilian, Lutz, and Pesavento, Elena
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MACROECONOMICS ,NONLINEAR analysis ,MONTE Carlo method ,COEFFICIENTS (Statistics) ,DATA analysis - Abstract
Nonlinearities play an increasingly important role in applied work when studying the responses of macroeconomic aggregates to policy shocks. Seemingly natural adaptations of the popular local linear projection estimator to nonlinear settings may fail to recover the population responses of interest. In this paper we study the properties of an alternative nonparametric local projection estimator of the conditional and unconditional responses of an outcome variable to an observed identified shock. We discuss alternative ways of implementing this estimator and how to allow for data-dependent tuning parameters. Our results are based on data generating processes that involve, respectively, nonlinearly transformed regressors, state-dependent coefficients, and nonlinear interactions between shocks and state variables. Monte Carlo simulations show that a local-linear specification of the estimator tends to work well in reasonably large samples and is robust to nonlinearities of unknown form. [ABSTRACT FROM AUTHOR] more...
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- 2024
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16. Robustness assessment of semi-rigid steel multi-storey frames
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Gomes, Vitor Rodrigues, Tenchini, André, Lima, Luciano, and Vellasco, Pedro
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- 2020
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17. Stability analysis and retrieval of new solitary waves of (2+1)- and (3+1)-dimensional potential Kadomtsev–Petviashvili and B-type Kadomtsev–Petviashvili equations using auxiliary equation technique.
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Sağlam, Fatma Nur Kaya and Ahmad, Shabir
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NONLINEAR differential equations , *PARTIAL differential equations , *NONLINEAR equations , *THEORY of wave motion , *NONLINEAR analysis - Abstract
The Kadomtsev–Petviashvili (KP) equations are nonlinear partial differential equations which are widely used for the modeling of wave propagation in hydrodynamic and plasma systems. This study aims to make a valuable contribution to the literature by providing new solitary waves to the (2+1)- and (3+1)-dimensional potential Kadomtsev–Petviashvili (pKP)-B-type Kadomtsev–Petviashvili (BKP) equations. For this, the auxiliary equation method associated with Bernoulli equation is used and new solutions for the considered equations are obtained. The stability of obtained solutions is demonstrated using nonlinear analysis. It is shown that this method for the considered pKP–BKP equations is an important step forward in an overall mathematical framework for similar equations. [ABSTRACT FROM AUTHOR] more...
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- 2025
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18. MainModelingStr: A Structural Dynamic Nonlinear Analysis Framework with Adaptive Beam-Column Finite Elements.
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Martinez, Edgar David Mora and Khaji, Naser
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NONLINEAR analysis , *FINITE element method , *MATRIX functions , *INTERPOLATION , *POLYNOMIALS - Abstract
This study introduces a new method for nonlinear structural analysis of buildings using high-order Hermitian interpolation function matrices for Timoshenko elements. This method aims to improve the accuracy of traditional beam-column finite element analyses by using higher-order shape function polynomials. Thus, a
p -adaptive procedure is employed to address the potential issues of increased complexity and round-off error associated with higher-order functions. The study uses a technique for removing outliers in thep -adaptive method, which is more consistent with the theoretical approach. Moreover, a novel strategy based on the generalized alpha method is applied to reduce even more convergence problems, allowing its parameters to adapt in each instant of the time-history analysis. These adaptive parameters permit setting a low tolerance error and avoiding changing these parameters manually in time-consuming analyses. The efficiency of using fourth-order beam-column elements is also investigated. Finally, the importance of the proposed method is demonstrated through examples of building analyses, which is the base of a proposed software called MainModelingStr. [ABSTRACT FROM AUTHOR] more...- Published
- 2025
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19. Chaotic band-gap modulation mechanism for nonlinear vibration isolation systems based on time-delay feedback control.
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Zhang, Yongyan, Liu, Qinglong, Wu, Jiuhui, Liu, Hui, Yang, Leipeng, Zhao, Zebo, Chen, Liming, Chen, Tao, and Li, Suobin
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FEEDBACK control systems , *BASE isolation system , *NONLINEAR analysis , *SYSTEMS design , *SYSTEM dynamics , *QUANTUM chaos , *VIBRATION isolation - Abstract
Systems designed for nonlinear vibration isolation that incorporate chaotic states demonstrate superior capabilities in vibration attenuation, adeptly modulating the spectral constituents of vibrational noise. Yet, the challenge of eliciting low-amplitude chaotic dynamics and perpetuating these states across a diverse array of parameters remains formidable. This study proposes a pioneering strategy and technique for modulating the chaos band by incorporating a time-delayed feedback control mechanism within the framework of nonlinear vibration isolation systems.The investigation commences with an exhaustive analysis of the nonlinear dynamics, shedding light on the principles dictating the evolution of chaos. The study then advances to scrutinize the dynamics of systems with delays to elucidate the chaos-inducing processes engendered by feedback with temporal lags. Building upon the system's responses, the chaotic performance and the effectiveness of the vibration isolation are crafted. Consequently, the time-delayed feedback control parameters are identified as pivotal design variables, which are then employed to dissect the control mechanisms influenced by the time-delayed feedback on the chaos band. Utilizing the delineated control mechanism, the nonlinear vibration isolation system is precipitously transitioned from a state of stable periodicity to one of chaos, fostering low-amplitude chaotic dynamics across an expansive parameter space, and in turn, resolving the previously stated challenge. Perhaps most significantly, the mechanism for attaining low-amplitude chaos introduced here paves the way for innovative methodologies in the active vibration isolation design of similar systems. Furthermore, it is anticipated to yield theoretical guidance for the manipulation of chaos bands and the formulation of active vibration isolation strategies within the domain of nonlinear vibration isolation systems. [ABSTRACT FROM AUTHOR] more...
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- 2025
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20. Sparse kernel k-means clustering.
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Park, Beomjin, Park, Changyi, Hong, Sungchul, and Choi, Hosik
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ANALYSIS of variance , *TENSOR products , *CLUSTER analysis (Statistics) , *NONLINEAR analysis , *DATA analysis - Abstract
Clustering is an essential technique that groups similar data points to uncover the underlying structure and features of the data. Although traditional clustering methods such as k-means are widely utilized, they have limitations in identifying nonlinear clusters. Thus, alternative techniques, such as kernel k-means and spectral clustering, have been developed to address this issue. However, another challenge arises when irrelevant variables are present in the data; this can be mitigated by employing variable selection methods such as the filter, wrapper, and embedded approaches. In this study, with a particular focus on kernel k-means clustering, we propose an embedded variable selection method using a tensor product space along with a general analysis of variance kernel for nonlinear clustering. Comprehensive experiments involving simulations and real data analysis demonstrated that the proposed method achieves competitive performance compared to existing approaches. Thus, the proposed method may serve as a reliable tool for accurate cluster identification and variable selection to gain insights into complex datasets. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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21. Mechanical Properties and Nonlinear Energy Evolution of Holed Limestone Under Hydro-Mechanical Coupling.
- Author
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Zhu, Kaixin, Zhong, Zuliang, Wang, Nanyun, and Li, Zezhou
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NONLINEAR oscillations , *CRACK propagation (Fracture mechanics) , *COUPLINGS (Gearing) , *NONLINEAR analysis , *LIMESTONE - Abstract
To investigate the mechanical properties and nonlinear energy evolution mechanism of holed limestone, triaxial compression tests under hydro-mechanical coupling were conducted on holed limestones with varying hole numbers. Based on nonlinear dynamics and rock micro-energy evolution theory, the chaotic characteristics of the energy evolution process were explored. The results show that under the action of hydro-mechanical coupling, the peak strength and residual strength of the holed limestone increase with the increase of confining pressure, and the maximum increase ratios are 25.17% and 89.33%, respectively. With the increase of hole numbers and pore pressure, the maximum decreases are 22.32%, 46.07% and 17.39%, 52.81%, respectively. The deformation and failure process of holed limestone can be divided into the following five stages: nonlinear oscillation, nonlinear transcritical stability weakening, nonlinear stability, period-doubling bifurcation before chaos, and the chaotic stage. When stress reaches 81% of the peak stress, the crack periodically expands in the rock, and as it reaches 83%, the crack irregularly expands in the rock. When the energy growth factor r is 3 and 3.57, the corresponding periodic crack propagation stress σ pcg and chaotic initial stress σ cis can be considered as crack initiation stress and crack damage stress, which provides a new method for determining crack initiation stress and crack damage stress. The periodic crack propagation stress (representing crack initiation stress) and chaotic initial stress (indicating crack damage stress) of holed rocks gradually decrease with the increase in hole number and pore pressure, and gradually increase with the increase in confining pressure. Highlights: A triaxial specimen model was established based on karst fracture-pipe erosion. The effects of confining pressure, pore pressure, and hole number on the strength of holed limestone under hydro-mechanical coupling were investigated Two new nonlinear indexes are defined based on the relationship between the r value and stress increment It provides a new method for determining crack initiation stress and crack damage stress [ABSTRACT FROM AUTHOR] more...
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- 2025
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22. A hybrid-stress formulation based reduced-order method using a solid-shell element for geometrically nonlinear buckling analysis.
- Author
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Li, Zheng and Liang, Ke
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THIN-walled structures , *CIVIL engineering , *NONLINEAR analysis , *STRAIN energy , *VARIATIONAL principles - Abstract
The high computational efficiency of the Koiter reduced-order methods for structural buckling analysis has been extensively validated; however the high-order strain energy variations in constructing reduced-order models is still time-consuming, especially when involving the fully nonlinear kinematics. This paper presents a reduced-order method with the hybrid-stress formulation for geometrically nonlinear buckling analysis. A solid-shell element with Green-Lagrange kinematics is developed for three-dimensional analysis of thin-walled structures, in which the numerical locking is eliminated by the assumed natural strain method and the hybrid-stress formulation. The fourth-order strain energy variation is avoided using the two-field variational principle, leading to a significantly lower computational cost in construction of the reduced-order model. The numerical accuracy of the reduced-order model is not degraded, because the third-order approximation to equilibrium equations is recovered by condensing the stress. Numerical examples demonstrate that although the fourth-order strain energy variation is not involved, the advantage in path-following analysis using large step sizes is not only unaffected, but also enhanced in some cases with respect to the displacement based reduced-order method. The small computational extra-cost for the hybrid-stress formulation is largely compensated by the reduced-order analysis. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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23. Nonlinear Isogeometric Analyses of Instabilities in Thin Elastic Shells Exhibiting Combined Bending and Stretching.
- Author
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Kalia, Subodh and Padhye, Nikhil
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ISOGEOMETRIC analysis , *ELASTIC plates & shells , *ELASTIC deformation , *FINITE differences , *NONLINEAR analysis - Abstract
Thin structures like shells are highly susceptible to mechanical instabilities. They can undergo large nonlinear elastic deformations while exhibiting combined bending and stretching modes of deformation. Here, we propose a new displacement-based finite element (FE) formulation based on the isogeometric discretization of Koiter's nonlinear shell theory and use of the method of dynamic relaxation (DR) to solve equilibrium configurations of problems involving fine-scale and hierarchical wrinkling and buckling. No imperfection seeding is required to trigger instabilities. The use of the NURBS basis provides a rotation-free, conforming, higher-order spatial continuity such that curvatures and membrane strains can be computed directly from interpolating the position vectors of the control points using spatial finite differences. The pseudo-dissipative FE dynamical system is updated through explicit time integration and made scalable for parallel computing using a message passing interface (MPI). The proposed FE method is successfully benchmarked against several numerical and experimental results. [ABSTRACT FROM AUTHOR] more...
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- 2025
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24. Γ-convergence analysis of the nonlinear self-energy induced by edge dislocations in semi-discrete and discrete models in two dimensions.
- Author
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Alicandro, Roberto, De Luca, Lucia, Palombaro, Mariapia, and Ponsiglione, Marcello
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EDGE dislocations , *NONLINEAR analysis , *ELASTICITY - Abstract
We propose nonlinear semi-discrete and discrete models for the elastic energy induced by a finite system of edge dislocations in two dimensions. Within the dilute regime, we analyze the asymptotic behavior of the nonlinear elastic energy, as the core-radius (in the semi-discrete model) and the lattice spacing (in the purely discrete one) vanish. Our analysis passes through a linearization procedure within the rigorous framework of Γ-convergence. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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25. Nonlinearity, Heterogeneity and Indirect Effects in the CO2 Emissions-Financial Development Relation From Partial Linear Additive Panel Model.
- Author
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Xiaoping Cong, Xingyu Wang, and Qichang Xie
- Subjects
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FINANCIAL performance , *ECONOMIC systems , *NONLINEAR analysis , *INVESTMENT policy , *INDIVIDUAL differences - Abstract
Assessing the effect of financial development on carbon pollution has recently attracted growing interest due to the important role of finance in the overall economic and energy system. However, numerous studies explored the direct impact of financial performance from an aggregate perspective, which ignores the potential nonlinear and indirect effects. By generating a new financial development index covering banks, insurance, and securities, this paper introduces a partial linear additive panel model with data-driven features to simultaneously explore the direct and indirect impacts of China's financial development on CO2 emissions from nonlinear perspectives. Moreover, instead of the traditional linear marginal analysis, we perform a nonlinear marginal analysis and implement a spatial analysis to address the above objectives. The results manifest that the direct impact of financial development on CO2 discharges is a nonlinear "U-shaped"; In contrast, the moderation effect through economic growth suggests that financial development contributes to reducing CO2 concentrations. Marginal analysis shows that the effect of financial development on CO2 emissions not only exhibits individual differences but also reflects the characteristics of temporal transition. The results of spatial analysis verify that the development of finance has prominent spatial effects on CO2 discharges. The findings have important policy implications on how to effectively promote financial development to formulate more flexible investment policies and differentiated energy strategies. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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26. Precise analysis of geometrical nonlinear mechanical behavior of shear deformable laminated curved composite beams in local coordinates via mixed type finite elements.
- Author
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Kömürcü, Sedat and Doğruoğlu, Ali Nuri
- Subjects
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LAMINATED composite beams , *TIMOSHENKO beam theory , *NONLINEAR analysis , *FINITE element method , *NONLINEAR differential equations , *COMPOSITE construction - Abstract
In the present article, geometrically nonlinear analyses of curved laminated composite beams are carried out using Mixed Finite Element Method (MFEM). Timoshenko beam theory is used to consider shear influence which significantly effects the structural behavior of composite layers. Energy-based functional is generally needed to perform geometric nonlinear analyzes of layered composites. However, obtaining energy-based functional in geometric nonlinear theory is quite challenging due to the difficulty of solving mathematically nonlinear differential equations. In this study, this situation is overcome and a functional suitable for performing geometric nonlinear analyzes of layered composite materials is obtained. Incremental formulation procedure is utilized as a solution method for nonlinear finite element analyzes. This is an innovative application of the non-linear mixed finite element method and has the ability to perform geometric nonlinear analysis of curved laminated composite beams with perfect precision. By obtaining the functional in local coordinates, it is possible to solve special problems in various fields such as construction, machinery, aerospace and biomechanics. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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27. Weakly nonlinear instability analysis in triple‐diffusive convection under gravity modulation in the presence of an internal heat generator.
- Author
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Jakhar, Atul, Anurag, and Kumar, Anand
- Subjects
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RAYLEIGH number , *SPACE vehicles , *NONLINEAR analysis , *HEAT transfer , *WIND turbines - Abstract
The presented study is prepared on the triple‐diffusive convection (TDC) in the presence of an internal heat source to examine the rate of heat and mass transport. The weakly nonlinear instability analysis was used to show the effect of gravity modulation. Such phenomena have been found in space vehicle technology, wind turbines, geothermals, and many more. In the realm of geometry, our analysis encompasses the study of two parallel infinite horizontal plates with gravity in the downward direction. For TDC, we have considered two solutes. For the result validation, we have compared the critical Rayleigh number with the available research. The numerical outcomes are presented through graphs for different physical parameters. Based on the outcomes, we conclude that the Richardson, Prandtl, and Lewis numbers increase the mass and heat transport. The main finding of the present article is of the internal heat source that advances convection. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
- Full Text
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28. Effects of Loading Frequency on Soil–Pile Interaction Using Numerical Nonlinear Three-Dimensional Analyses.
- Author
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Ahmadi, Mohammad M., Hadei, Sadjad, Borzeshi, Sajjad A., and Hokmabadi, Arash
- Subjects
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BENDING moment , *TIME-domain analysis , *CYCLIC loads , *NONLINEAR analysis , *THREE-dimensional modeling , *SEISMIC response - Abstract
The kinematic interaction between piles under seismic loading has been extensively studied from analytical, experimental, and numerical perspectives. Of note, within numerical modeling, the majority of the existing literature relies on simplified approaches for characterizing the soil–pile interaction, which leads to the requirement for more reliable and comprehensive research. In this paper, using FLAC3D, the seismic response of the soil–pile system was investigated with a set of fully nonlinear three-dimensional (3D) numerical analyses in the time domain. This model simulated the soil strength and stiffness dependency on the stress level and soil nonlinear behavior under cyclic loading. The Mohr–Coulomb (M–C) constitutive model described the soil's mechanical behavior, which was used with additional hysteretic damping to suit the dynamic behavior. In the framework of a parametric study, the effects of loading frequency on the response of a soil–pile system that was subjected to seismic loading were studied. The results showed that the pile response and soil characteristics, as well as the natural frequency mode of the system's dynamic behavior, are strongly affected by the frequency of the seismic loading. Therefore, the bending moment and lateral displacement along the length of a pile increase as the loading frequency approaches the natural frequency of the system. In addition, when the loading frequency reaches a threshold value far from the fundamental frequency of the system, the effect of loading frequency on the soil–pile system response becomes negligible. In addition, the relationship between the pile diameter and maximum pile bending moment at different loading frequencies is affected by the soil properties. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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29. Institutional overlap and the survival of intergovernmental organisations.
- Author
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Reinsberg, Bernhard
- Subjects
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NONLINEAR regression , *INTERNATIONAL organization , *NONLINEAR analysis , *REGRESSION analysis , *SOCIAL networks - Abstract
A burgeoning literature emphasises the role of favourable external conditions and institutional design as key drivers of the survival of intergovernmental organisations. This article focuses on institutional overlap as a hitherto overlooked determinant of IGO survival. Studies on institutional complexity posit that overlap – the extent to which organisations perform similar tasks to address similar problems for some common members – may decrease the survivability of IGOs due to rule conflicts, institutional paralysis, and competitive pressures for limited resources. Contrary to this perspective, this article argues that greater overlap increases the likelihood of IGO survival for two reasons. First, similar IGOs will survive as member states use them to pursue forum-shopping strategies. Second, overlap enables IGO secretariats to draw on networks of support from other IGOs, rendering organisations that densely overlap with others more resilient. To test these propositions, the article combines data on institutional overlap in global governance and the survival of the 534 IGOs contained in the Correlates of War IGO dataset. Non-linear regression analysis finds that where organisations overlap more with existing organisations in terms of governance tasks and issue areas, the likelihood of IGO survival increases. Further analysis suggests that this result is driven by the forum-shopping strategies of powerful member states. Given that contemporary world politics is governed by an increasingly dense network of IGOs, these results hold important implications for the study of IGO survivability and the evolution of global governance more broadly. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
- Full Text
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30. Collapse of helical cylindrical shells subjected to external hydrostatic pressure.
- Author
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Wang, Xiaoyong, Tang, Wenxian, Zhuang, Hong, Xue, Weixuan, Zhang, Jian, and Zhan, Ming
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CYLINDRICAL shells ,NONLINEAR analysis ,EIGENVALUES - Abstract
The present study investigated the collapse performance of helical cylindrical shells subjected to external pressure. Helical cylindrical shells, cylindrical shells, and helically stiffened cylindrical shells were designed, fabricated, geometrically measured, and hydrostatically tested. Linear eigenvalue and nonlinear Riks analyses were performed to evaluate the collapse properties of the fabricated shells. The experimental and numerical results of this study were in agreement. In addition, the existing shapes of shells were used to make a comparison with the helical cylindrical shell. The effects of the spiral rib and wall thickness on the collapse properties of helical cylindrical shells were investigated numerically. The results indicated that a helical cylindrical shell with a spiral cambered surface and spiral rib has considerably higher loading capacity than an ordinary cylindrical shell does. A spiral rib can improve the collapse behaviour of helical cylindrical shells and change their collapse modes. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
- Full Text
- View/download PDF
31. Exact tracking of nonlinear systems under triggering state signals.
- Author
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Wei, Shu-Yi and Li, Yuan-Xin
- Subjects
NONSMOOTH optimization ,BACKSTEPPING control method ,NONLINEAR systems ,ADAPTIVE control systems ,NONLINEAR analysis - Abstract
This paper concentrates on the event-triggered adaptive asymptotic tracking control problem for a class of nonlinear systems. By using the neural network, the unknown nonlinearities existing in the systems are skilfully addressed. To save communication resources, a state-related event-triggered mechanism (ETM) is devised that only when the triggering condition is violated, the system states are sampled and transmitted to the controllers to update parameters. Because the incorporation of the state-related ETM has caused the state signals to be sporadic, a non-smooth analysis is performed. It is strictly proved that the tracking error asymptotically converges to the origin and the communication burden from the sensor-to-controller (S-C) channels is reduced. Meanwhile, the lower bound of the inter-execution interval is proved to be a constant. Finally, a simulation example confirms the benefits of the developed scheme. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
- Full Text
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32. Preference relations and Coradiants in ℝn.
- Author
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Hosseini Dehmiry, Alireza and Askarizadeh, Abbas
- Subjects
CONVEX sets ,NONLINEAR analysis ,SIMPLICITY - Abstract
Convex cones are closely related to preference relations and play an important role in optimization. Corresponding to any convex cone, a binary relation can be defined, but the reverse is not true. Therefore, many binary relations are discarded in the optimization. This paper is an attempt to define or prove the prerequisites for using convex coradiant sets (coradiants for simplicity) instead of convex cones so that more binary relations can be used in optimization and nonlinear analysis. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
- Full Text
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33. Dynamic modeling and response analysis of misaligned rotor system with squeeze film dampers under maneuver loads.
- Author
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Pan, Wujiu, Hao, Junkai, Li, Hongshuang, Wang, Junyi, Bao, Jianwen, Zeng, Xianjun, and Nie, Peng
- Abstract
The low-pressure rotor system of an aircraft engine includes a fan rotor and a low-pressure turbine rotor, which are connected and fixed by a gear coupling. The existence of machining errors and assembly errors can cause rotor assembly misalignment, which is one of the important factors causing aircraft engine failures. Based on the finite element matrix set theory, this paper establishes a dynamic model of the aircraft engine rotor system, including the climbing maneuver load, nonlinear contact force of bearings, oil film force of SFDs, gravity field, additional force caused by coupling misalignment, and rotor misalignment imbalance force, considering the climbing maneuver load. Using Newmark-β algorithm to solve the misaligned rotor system model with SFDs. The influence of misalignment stiffness, clearance of the oil film, and bearing clearance on the motion state of the rotor system were analyzed in detail through bifurcation diagrams, axis trajectory diagrams, and frequency spectra. And analyze and cross compare the effects of three influencing factors on the system motion state under different maneuvering load environments. Through comparative analysis, it was found that among these three influencing factors, the misalignment stiffness of the sleeve coupling has the smallest effect on the system's motion state, but an appropriate intermediate value needs to be selected. The effect of rolling bearing clearance on the system's motion state is small and regular, while the impact of oil film clearance on the system's motion state is large and complex. The research results of this paper can provide theoretical support for parameter selection in the simulation and design of dynamic phenomena with misalignment faults in aircraft engines during maneuvering flight. [ABSTRACT FROM AUTHOR] more...
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- 2025
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34. Target‐drift seismic‐force‐based design of one‐story reinforced concrete precast buildings considering the requirements of the second generation of the Eurocode 8 standard.
- Author
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Isaković, Tatjana
- Subjects
COLUMNS ,NONLINEAR analysis ,REINFORCED concrete ,REINFORCED concrete buildings ,ELASTIC analysis (Engineering) - Abstract
Results are presented concerning the force‐based design of a wide range of reinforced concrete, single‐story precast buildings, considering the requirements of the new Eurocode 8 standard. The relevant criterion defining the cross‐sectional dimensions of the columns was the 2% drift limitation. Buildings were designed considering a behavior factor of 3 and a 50% reduction in stiffness corresponding to the gross cross‐section. The design evaluation, using a nonlinear pushover analysis, revealed that all the buildings could expect approximately twice the drift considered in the design with significant second‐order effects, particularly in very tall columns. The main reasons for large discrepancies between the elastic and nonlinear analyses were the arbitrarily selected behavior factor and the arbitrarily selected reduction in stiffness corresponding to the gross cross‐section (the stiffness considered in the design was approximately double what the nonlinear analysis revealed). The analysis revealed that these two quantities are closely correlated. Once the dimensions of the columns had been selected, the force and initial stiffness reduction could not be chosen arbitrarily. Correlations were determined between the column dimensions, theoretical stiffness reduction, seismic force reduction (behavior factor) and second‐order effects. From these correlations, a new target‐drift force‐based design methodology was proposed. All considered buildings were redesigned using the proposed method. The results of the new design and the nonlinear‐pushover‐based analysis correlated well. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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35. Seismic design of steel moment‐resisting knee‐braced frame system by failure mode control.
- Author
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Sepahvand, Mostafa Fathi and Lenwari, Akhrawat
- Subjects
EARTHQUAKE resistant design ,GROUND motion ,GAME theory ,SYSTEM failures ,FAILURE mode & effects analysis - Abstract
This paper presents the seismic design of a steel moment‐resisting knee‐braced frame (MKF) using the theory of plastic mechanism control (TPMC) within the capacity‐based design framework. The MKF is an alternative system to MRFs, wherein knee elements are utilized to provide rigid connections and enhance lateral stiffness. Capacity‐based design, the predominant approach in current seismic provisions, relies on two key principles: (1) selecting specific structural components as fuses with sufficient ductility to dissipate seismic energy, and (2) ensuring non‐fuse elements can resist the maximum probable reactions from these fuses. The ultimate goal is to achieve a global mechanism where yielding occurs in all structural fuses and at the base of first‐story columns. However, existing seismic design provisions often struggle to fully satisfy the second principle due to the lack of a method for controlling failure modes. TPMC addresses this challenge by ensuring compliance with the second principle, grounding its approach in the kinematic method and the mechanism equilibrium curve within the rigid‐plastic analysis framework. By considering all potential story‐based undesirable mechanisms and calculating the required plastic moment of columns up to a target design displacement, TPMC ensures adherence to the second principle of the capacity‐based design approach, leading to the achievement of a global collapse mechanism. In this paper, an iterative method is proposed for designing beams and knee elements by considering plastic hinges at both ends of the beams, followed by a TPMC‐based methodology for designing columns to ensure a global mechanism. A parametric analysis of a single‐story single‐span MKF explores the effects of knee element geometry (lb/L${l}_b/L$ and β$\beta $) on component demands. The results indicate that optimal parameter ranges of 0.175≤lb/L≤0.25$0.175 \le {l}_b/L \le 0.25$ and 40∘≤β≤60∘$40^\circ \le \beta \le 60^\circ $ can minimize the demands for MKF components. Practical design examples are illustrated using three steel MKFs, each consisting of four, seven, and ten stories with five spans. Pushover analysis and nonlinear dynamic analyses were performed to demonstrate the effectiveness of the proposed design procedure in ensuring the attainment of a global mechanism and excellent seismic performance under real ground motions. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
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36. Edge-preserving smoothing of Perona-Malik nonlinear diffusion in two-dimensions.
- Author
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Alaoui, Anas Tiarimti and Jourhmane, Mostafa
- Subjects
NONLINEAR analysis ,EDGE detection (Image processing) ,IMAGE processing ,IMAGING systems ,DIRECTIONAL derivatives - Abstract
It has been thirty years since Perona and Malik (PM) introduced the nonlinear diffusion equation in image processing and analysis. The problem's complexity was to find a suitable and adaptive diffusion function that smooths away noise or textures while preserving sharp edges of a sufficiently smooth intensity. This paper provides a new two-dimensional analysis of the PM diffusion equation to examine its behavior during scales and an explicit formula to select the right diffusion function adequately. In this context, we study the PM equation at the zero crossings of the first and second directional derivatives of a sufficiently smooth function in the gradient direction. [ABSTRACT FROM AUTHOR] more...
- Published
- 2025
- Full Text
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37. Thermal postbuckling strength improvement prediction of Shape Memory alloy fiber embedded damaged layered composite structure.
- Author
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Kumar, Erukala Kalyan, Akkasali, Naveen Kumar, Mehar, Kulmani, Mehar, Amit Kumar, and Panda, Subrata Kumar
- Subjects
- *
SHAPE memory alloys , *FINITE element method , *COMPOSITE structures , *CRITICAL temperature , *NONLINEAR analysis - Abstract
AbstractThe postbuckling critical temperature values for the damaged smart (shape memory alloy fiber-reinforced) layered composite are computed numerically (using MATLAB code)
via a higher-order mathematical model. The geometrical distortion of the panel is modeled mathematically using higher-order kinematics and Green-Lagrange strain. The model includes both nonlinearities, i.e. the geometry (due to large distortion) and material (because of smart fiber). The marching technique introduced the material nonlinearity as a function of the temperature cycle. The critical thermal load values are obtained by solving the nonlinear eigenvalue. The code is validated and extended to understand the influences of parameters on postbuckling temperatures. [ABSTRACT FROM AUTHOR] more...- Published
- 2024
- Full Text
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38. Isogeometric analysis of hyperelastic Timoshenko beams under large deformation and incompressibility constraints.
- Author
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Sahnoun, Abdelfettah, Bekhoucha, Ferhat, and Ameur, Houari
- Subjects
- *
CURVED beams , *VIRTUAL work , *CONSERVATISM (Accounting) , *NONLINEAR equations , *NONLINEAR analysis , *NEWTON-Raphson method - Abstract
This article investigates the nonlinear analysis of hyperelastic planar curved beams based on the total Lagrangian Timoshenko theory. The fully incompressible neo-Hookean model has been selected as the constitutive relation to accurately capture large deformations. The nonlinear equations and boundary conditions derived from the virtual work principle are solved using the Newton–Raphson method. Employing isogeometric analysis with NURBS functions to discretize the unknown kinematics, including displacements and rotation, and the linearized governing equations. The study accounts for conservative and non-conservative forces, validating results against available experimental and numerical results reported in the literature, confirming the proposed formulation's effectiveness and precision. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
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39. Output Formation Containment of Heterogeneous Singular Multiagent Systems Using Adaptive Protocols.
- Author
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Liu, Xiaofan, Sheng, Kai, and Yan, Yunyi
- Subjects
- *
NONLINEAR systems , *NONLINEAR analysis , *MULTIAGENT systems - Abstract
ABSTRACT In this study, the output formation containment control problem for heterogeneous singular multiagent systems is investigated. The purpose of this study is to drive the output of the leader agents to reach a time‐varying formation and take containment action for the follower agents. First, a novel distributed adaptive protocol is designed that relies on the relative output information of agents without measuring and transmitting their states information. Then, the formation containment control problem can be simplified into an admissible analysis of coupled nonlinear singular systems by constructing a model transformation. The output formation control conditions related to the spectral radius of the weighted adjacency matrix are obtained based on the bounded real lemma and admissible analysis. In addition, the adaptive protocols based on the state of the virtual leader are proposed, which can drive the agents to achieve formation containment control more quickly when the state of the virtual leader is known. Finally, the simulation results verify the feasibility of the output formation containment control. [ABSTRACT FROM AUTHOR] more...
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- 2024
- Full Text
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40. Fast analysis and prediction approach for geometrically nonlinear bending analysis of plates and shells using artificial neural networks.
- Author
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Nguyen, T. N., Zhang, Dongsheng, Mirrashid, Masoomeh, Nguyen, Dinh Khuong, and Singhatanadgid, Pairod
- Subjects
- *
ARTIFICIAL neural networks , *NONLINEAR analysis , *NONLINEAR equations , *ALGORITHMS - Abstract
For the first time, this paper introduces a Fast Analysis and Prediction (FAP) approach for geometrically nonlinear bending analysis of plates and shells. The proposed approach consists of two phases: fast analysis and prediction using artificial neural networks (ANNs) combined with the Bayesian regularization algorithm. In the first phase (fast analysis), geometrically nonlinear bending analysis of a structure is performed using only several load steps. This enables the efficient computation within a short period of time. In the second phase (prediction using ANNs), the deflections obtained in the first phase are utilized as the data for training the ANNs. The trained networks are then used to quickly predict deflections at any load step. The calculation process in the second phase is also very fast. For the analysis package in the first phase, the formulation of this paper is originated from the literature for geometrically nonlinear analysis of composite shells. High accuracy and efficiency of the FAP approach were demonstrated via solving nonlinear bending problems of plates and shells including an isotropic square plate, a composite cylinder subjected to internal pressure, a FG-CNTRC panel and a pinched cylinder with end diaphragms. The proposed approach offers significantly computational savings (up to 70%) compared to the conventional one. ANNs combined with the Bayesian regularization algorithm, which are proposed for the FAP approach in this work, possess the outstanding advantages compared to many existing neural networks. The FAP approach can be applied to simulations, observations, or experiments where nonlinear responses are present or data is limited. Applying the FAP approach to such areas can significantly save labor, time, and money. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
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41. Nonlinear inelastic analysis of space semi-rigid steel frames subjected to static load using plastic-zone method.
- Author
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Le-Van, Binh, Chiorean, Cosmin-Gruia, Kim, Seung-Eock, and Ngo-Huu, Cuong
- Subjects
- *
MATERIAL plasticity , *NONLINEAR equations , *DEAD loads (Mechanics) , *NONLINEAR analysis , *STEEL framing - Abstract
A new hybrid element based on plastic-zone method is proposed for static nonlinear analysis of space semi-rigid steel frames. Four zero-length nonlinear rotational springs are added to the beam ends to model both in- and out-of-plane connection rotational behavior with appropriate semi-rigid connection models. The von Mises yield criteria are applied to govern material plasticity along the member length and throughout the cross-section using Newton–Cotes integration points. The modified generalized displacement control method is used to solve the system of nonlinear equilibrium equations. Some numerical examples are investigated to show the reliability and visual illustration of the proposed hybrid element. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
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42. Analysis of transversely isotropic compressible and nearly-incompressible soft material structures by high order unified finite elements.
- Author
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Chiaia, Piero, Pagani, Alfonso, Cinefra, Maria, and Carrera, Erasmo
- Subjects
- *
NONLINEAR analysis , *STRAIN energy , *FINITE element method , *ENERGY function , *STRAIN tensors - Abstract
This work proposes high-order beam (1D) and plate (2D) finite element models for the large strain analysis of compressible and incompressible transversely isotropic hyperelastic media, defined within the Carrera Unified Formulation (CUF) framework. The strain energy density function adopted in fiber-reinforced hyperelastic materials modeling is presented and expressed in terms of invariants and pseudo-invariants of the right Cauchy-Green strain tensor. The explicit expression of the tangent elasticity tensor is derived through the assumption of coupled formulation of strain energy functions. Refined fully nonlinear beam and plate models are defined in a total Lagrangian formulation, deriving the governing equations of the nonlinear static analysis through the Principle of Virtual Displacements in terms of fundamental nuclei, in resulting expressions of internal and external forces vectors, and tangent stiffness matrix independent of kinematic models and approximation theories adopted. The iterative Newton-Raphson linearization scheme coupled with the arc-length constraint is adopted to obtain actual numerical solutions. Different benchmark analyses in hyperelasticity are performed to assess the capabilities of our proposed model, analyzing the three-dimensional stress field for moderate to large strain states and comparing actual numerical results with exact closed-form solutions or results available in the literature, demonstrating the capabilities and reliability of CUF models in the analysis of fiber-reinforced soft materials and structures. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
43. A mixed hexahedral solid‐shell finite element with self‐equilibrated isostatic assumed stresses for geometrically nonlinear problems.
- Author
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Liguori, Francesco S., Zucco, Giovanni, and Madeo, Antonio
- Subjects
STRAINS & stresses (Mechanics) ,DISPLACEMENT (Psychology) ,STRAIN tensors ,NONLINEAR equations ,NONLINEAR analysis - Abstract
Mixed Finite Elements (FEs) with assumed stresses and displacements provide many advantages in analysing shell structures. They ensure good results for coarse meshes and provide an accurate representation of the stress field. The shell FEs within the family designated by the acronym Mixed Isostatic Self‐equilibrated Stresses (MISS) have demonstrated high performance in linear and nonlinear problems thanks to a self‐equilibrated stress assumption. This article extends the MISS family by introducing an eight nodes solid‐shell FE for the analysis of geometrically nonlinear structures. The element, named MISS‐4S, features 24 displacement variables and an isostatic stress representation ruled by 18 parameters. The displacement field is described only by translations, eliminating the need for complex finite rotation treatments in large displacements problems. A total Lagrangian formulation is adopted with the Green–Lagrange strain tensor and the second Piola–Kirchhoff stress tensor. The numerical results concerning popular shell obstacle courses prove the accuracy and robustness of the proposed formulation when using regular or distorted meshes and demonstrate the absence of any locking phenomena. Finally, convergences for pointwise and energy quantities show the superior performance of MISS‐4S compared to other elements in the literature, highlighting that an isostatic and self‐equilibrated stress representation, already used in shell models, also gives advantages for solid‐shell FEs. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
44. Bifurcation and Global Stability of a SEIRS Model With a Modified Nonlinear Incidence Rate.
- Author
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Amin, Shilan, Majeed, Saiwan, Aziz, Sozan, Mustafa, Arkan, and Kumar, Kamal
- Subjects
- *
OVERALL survival , *SENSITIVITY analysis , *NONLINEAR analysis , *COMPUTER simulation , *EQUILIBRIUM - Abstract
In this work, a SEIRS (susceptible–exposed–infected–recovered–susceptible) model with modified nonlinear incidence rate is considered. The incidence rate illustrates how the number of infected individuals initially increases at the onset of a disease, subsequently decreases due to the psychological effect, and ultimately reaches saturation due to the crowding effect. Firstly, we determine the existence criteria for the model equilibrium points, followed by the identification of the threshold quantity for disease survival; R0 determines whether the disease dies out or not. We analyze both the local and global stability of the associated equilibria. The dynamics of the model are complex due to its forward and backward bifurcations. Finally, we perform some numerical simulations to illustrate the impact of the analytical findings observed in the works. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
45. Fragility analysis of a triangular free‐form reinforced concrete shell.
- Author
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Garcia, Maya Sian Caycedo, Siqueira, Gustavo Henrique, Vieira Junior, Luiz Carlos Marcos, Cárdenas, Diego Rafael Joya, and Vizotto, Isaias
- Subjects
- *
MECHANICAL behavior of materials , *STRENGTH of materials , *STRUCTURAL stability , *REINFORCED concrete , *NONLINEAR analysis , *SOIL vibration - Abstract
Considering the importance of deepening the knowledge of the structural behavior of free‐form shell structures with a triangular plan, this work presents the results of research on the analysis of seismic vulnerability, verified through linear time‐history analysis (NLTHA), generating fragility curves through PSDM models. The analyzes carried out are based on uncertainties regarding both the mechanical properties of the materials and the geometric characteristics of the structures, as well as the action of seismic events. Real accelerograms, compatible with the elastic response spectra for Lisbon and Ouren, Portugal given by the EC8 standard, are used to consider seismic events. In the analyses, fundamental factors are considered, such as the accumulation of damage and the degradation in the resistance of materials. The structure presents highly ductile behavior in the face of seismic loads, attributed to its rigidity, geometry, lightness, and modal behavior, with participation in the horizontal components of the mass in the first five vibration modes greater than 80% and with minimal influence of the vertical component, characteristics inherent to this type of structure. However, it should be noted that the area close to the support, in the same direction as the ground acceleration, is the most vulnerable. This occurs due to the plastic yielding of the concrete during the earthquake, which promotes the appearance of cracks and compression damage. This is verified for the structure when subjected to earthquakes with PGA in the horizontal direction between 0.01 and 0.8 g. The probability of considerable damage increases with seismic events having PGA greater than 0.6 g, which, in turn, can compromise the stability of the structure. It is, therefore, of great importance to study the seismic behavior of shell structures, especially free‐form shells, considering the variability and uncertainties related to the structural stress arising from the seismic demand. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
46. Neuronal activity features of the subthalamic nucleus associated with optimal deep brain stimulation electrode insertion path in Parkinson's disease.
- Author
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Zakharov, Nikita, Belova, Elena, Gamaleya, Anna, Tomskiy, Alexey, and Sedov, Alexey
- Subjects
- *
DEEP brain stimulation , *PARKINSON'S disease , *THERAPEUTICS , *SUBTHALAMIC nucleus , *BRAIN diseases , *NONLINEAR analysis - Abstract
Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a standard treatment for advanced Parkinson's disease (PD). The precise positioning of the electrode can significantly influence the results of DBS and the overall improvement in the quality of life for PD patients receiving this therapy. We hypothesize that single unit activity (SUA) features can serve as a valid marker of the optimal DBS‐electrode insertion trajectory, leading to the most favorable outcome of STN‐DBS surgery. We analyzed spontaneous SUA data recorded during microelectrode recording (MER) for 21 patients with PD who underwent DBS surgery. We compared 29 linear and six nonlinear characteristics of the STN neural activity recorded along different microelectrode insertion paths to determine features corresponding to favorable stimulation outcomes. Our research indicated that the SUA features of pause neurons in a dorsal STN region significantly affected stimulation outcomes. For the trajectories chosen for lead insertion, firing rate, burst rate and oscillatory activity at 8–12 and 12–20 bands were significantly decreased. Moreover, nonlinear feature analysis showed a significant increase in mutual information for the chosen trajectories. Our findings highlight the significance of specific indicators, such as the activity of pause neurons in the dorsal region and numerous linear SUA characteristics, in determining the optimal lead installation trajectory. Furthermore, our findings emphasize the importance of investigating paths rejected during test stimulation to understand motor impairment in Parkinson's disease and its treatment mechanisms. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
47. A Geometric Numerical Integration with Simple Cell Mapping for Global Analysis of Nonlinear Dynamical Systems.
- Author
-
Huang, Fei-Long, Chen, Li-Qun, and Jiang, Wen-An
- Subjects
- *
NUMERICAL integration , *NONLINEAR systems , *NONLINEAR analysis , *ALGORITHMS - Abstract
In order to improve the efficiency in computing the global properties of nonlinear systems, some effective methods have been proposed for the global analysis of these systems. However, there are only few investigations focusing on the numerical algorithms of the system response trajectories. This paper presents a higher-efficiency geometric numerical integration method with simple cell mapping for solving the basins of attraction of nonlinear systems. This numerical algorithm is based on the rule of Lie derivative, using it to calculate the trajectories of the nonlinear systems. Then, the global structure is studied by the numerical algorithm associated with a simple cell mapping method. Compared with the traditional Runge–Kutta methods of orders 4 and 5, it is demonstrated that the proposed Lie derivative iterative algorithm has significant advantages in efficiency. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
48. Seismic performance of historic masonry buildings: A comparative analysis of equivalent frame and block-based methods.
- Author
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Fabbrocino, Francesco, Olivieri, Carlo, Luciano, Raimondo, Vaiano, Generoso, Maddaloni, Giuseppe, and Iannuzzo, Antonino
- Subjects
NONLINEAR analysis ,TILT-table test ,RETROFITTING ,DOMESTIC architecture ,COMPARATIVE studies ,HISTORIC buildings ,FACADES - Abstract
Many Italian historic buildings are located in earthquake-prone areas and, therefore, need effective seismic evaluations. Most widespread commercial codes are based on the Equivalent Frame Model (EFM). To investigate their reliability, particularly to assess the effect of tie-rod retrofitting interventions, the present research applies an EFM approach via 3Muri software to a detailed 3D digital model of Villa Vannucchi, a heritage building in southern Italy. The combined use of 3Muri for the 3D global behaviour and linear kinematic approaches for the 2D out-of-plane response shows the need for the installation of tie-rods. Looking at the 2D main facade, the effectiveness of 3Muri in capturing the beneficial effect of tie-rods is investigated against parametric analyses carried out with a standard limit analysis block-based method (BBM). Specifically, using the exact EFM's discretization and boundary conditions, the 3Muri results are benchmarked against the BBM adopting two modelling strategies: BBM pushover analysis with the same modelling strategy and loading conditions used by 3Muri, and BBM tilting tests. With the first strategy, it is shown that BBM provides results in good agreement with 3Muri; however, these results are independent of the tie-rod tension and presence because of inappropriate modelling of loading conditions. Conversely, the second strategy overcomes this drawback by better capturing the positive influence of the tie-rods both in terms of collapse mechanisms and an improved base shear capacity. The results of this research suggest that limit analysis represents a key, useful, and viable tool that needs to be integrated with EFM results in order to better capture the real effectiveness of tie-rod strengthening interventions, allowing for more sustainable consolidation strategies. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
49. On Transient Stability Problems in DC Microgrids.
- Author
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Niu, Decun, Wang, Ziyang, Chen, Minghao, and Fang, Jingyang
- Subjects
RENEWABLE energy sources ,NONLINEAR analysis ,SYSTEM dynamics ,VOLTAGE ,EQUILIBRIUM - Abstract
Transient stability, i.e., the ability of power systems to maintain synchronism when subjected to a severe disturbance, has extensively been investigated in AC grids. This article reveals that similar transient stability problems (but with different features) also exist in DC microgrids, as caused by the violation of power-transfer limitations between DC generators and grids. Through rigorous theoretical analysis and experimental validation, this article advances the field by establishing a comprehensive analytical framework that derives the equilibrium points, power-absorption limitations, and stable conditions of proportional–integral (PI) power-controlled and droop-controlled DC generators. The methodology combines small-signal stability analysis with large-signal nonlinear analysis to characterize the system dynamics under different control strategies. Our key findings demonstrate that droop-controlled generators benefit from better transient stability due to their enlarged stable operating region and enhanced robustness against voltage disturbances, which is particularly valuable for improving the reliability of renewable energy integration in DC microgrids. The theoretical analysis is comprehensively verified through experimental results using a prototype DC microgrid test platform. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
50. Association between residual cholesterol and sarcopenia in American adults.
- Author
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Li, Jianzhao and Lin, Yuning
- Subjects
LIPID metabolism ,LOGISTIC regression analysis ,NONLINEAR analysis ,SENSITIVITY analysis ,CHOLESTEROL ,SARCOPENIA - Abstract
Background: Remnant cholesterol (RC) is a novel lipid metabolism indicator; however, its relationship with sarcopenia has not been clearly established. This study was conducted to explore the association between RC and sarcopenia. Methods: An analysis was performed utilizing cross-sectional data from the NHANES 2011–2018. The variable RC was subjected to a logarithmic transformation to address its skewness. Logistic regression studies were conducted to examine the association between RC and sarcopenia. This study used restricted cubic spline (RCS) and threshold saturation techniques to investigate nonlinear connections. Subgroup, sensitivity, and additional analyses were performed to assess the robustness and validity of the findings. Results: The study included 4636 participants. Participants with sarcopenia had significantly higher RC levels. Logistic regression demonstrated a substantial positive association between the prevalence of sarcopenia and log RC (OR=1.69, 95% CI=1.32-2.17). RCS analysis revealed a nonlinear relationship, identifying a threshold at RC=25. When the RC is below this threshold, every one-unit increase in RC increases the chance of sarcopenia by 7% (OR=1.07, 95% CI=1.04-1.10); above this threshold, changes in RC were not significant. Subgroup analysis confirmed that RC was an independent risk factor for sarcopenia. The sensitivity and supplementary analyses supported the main findings. Conclusion: This study demonstrates a significant positive association between RC levels and the prevalence of sarcopenia in U.S. adults, offering novel evidence that RC may serve as a valuable indicator for sarcopenia assessment. [ABSTRACT FROM AUTHOR] more...
- Published
- 2024
- Full Text
- View/download PDF
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