Relevant bibliographies by topics / Local nonlinear geometric attacks

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers
  5. Reports

Academic literature on the topic 'Local nonlinear geometric attacks'

Author: Grafiati
Published: 4 June 2025
Last updated: 23 June 2025

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Journal articles on the topic "Local nonlinear geometric attacks"

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Baoru, Han. "A DIFFERENCE PERCEPTUAL HASHING ALGORITHM FOR MEDICAL VOLUME DATA AGAINST LOCAL NONLINEAR GEOMETRIC ATTACKS." International Journal of Innovative Research in Information Security VII, no. VIII (2020): 76–80. https://doi.org/10.26562/ijiris.2020.v0707.002.

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Traditional image hashing methods can often only resist traditional global geometric attacks and cannot resist local nonlinear geometric attacks. This has a huge impact on the protection, identification and authentication of three-dimensional medical volume data. In response to these problems, a new difference perceptual hashing algorithm for medical volume data is proposed in this paper. It uses the difference between adjacent elements in each column of the volume data feature matrix to generate a hashing sequence. Experiments show that it has a good ability to resist local nonlinear geometric attacks.
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Han, Baoru. "A DIFFERENCE PERCEPTUAL HASHING ALGORITHM FOR MEDICAL VOLUME DATA AGAINST LOCAL NONLINEAR GEOMETRIC ATTACKS." International Journal of Innovative Research in Information Security 7, no. 7 (2020): 76–80. http://dx.doi.org/10.26562/ijiris.2020.v0707.002.

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CUI, De-long, Jing-long ZUO, and Zhi-ping PENG. "Watermarking algorithm for resisting local nonlinear geometric attacks based on normed centre of gravity." Journal of Computer Applications 30, no. 8 (2010): 2161–63. http://dx.doi.org/10.3724/sp.j.1087.2010.02161.

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Han, Baoru, Jinglong Du, Yuanyuan Jia, and Huazheng Zhu. "Zero-Watermarking Algorithm for Medical Image Based on VGG19 Deep Convolution Neural Network." Journal of Healthcare Engineering 2021 (July 1, 2021): 1–12. http://dx.doi.org/10.1155/2021/5551520.

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Aiming at the security issues in the storage and transmission of medical images in the medical information system, combined with the special requirements of medical images for the protection of lesion areas, this paper proposes a robust zero-watermarking algorithm for medical images’ security based on VGG19. First, the pretrained VGG19 is used to extract deep feature maps of medical images, which are fused into the feature image. Second, the feature image is transformed by Fourier transform, and low-frequency coefficients of the Fourier transform are selected to construct the feature matrix of the medical image. Then, based on the low-frequency part of the feature matrix of the medical image, the mean-perceptual hashing algorithm is used to achieve a set of 64-bit binary perceptual hashing values, which can effectively resist local nonlinear geometric attacks. Finally, the algorithm adopts a watermarking image after scrambling and the 64-bit binary perceptual hashing value to obtain robust zero-watermarking. At the same time, the proposed algorithm utilizes Hermite chaotic neural network to scramble the watermarking image for secondary protection, which enhances the security of the algorithm. Compared with the existing related works, the proposed algorithm is simple to implement and can effectively resist local nonlinear geometric attacks, with good robustness, security, and invisibility.
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WU, Xuan, Zhou ZHOU, and Zhengping WANG. "Static aeroelastic analysis of very flexible wings coupled with distributed propellers." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 41, no. 6 (2023): 1044–53. http://dx.doi.org/10.1051/jnwpu/20234161044.

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Distributed propellers are widely used as propulsion for high-aspect-ratio long-endurance UAVs, and their load and slipstream will change the structural and aerodynamic characteristics of the wing, making geometric nonlinear effects more prominent. To address the aeroelastic interference of distributed propellers on the large flexible wing, firstly, on the basis of the vortex theory, a slipstream tube model is used to rapidly calculate the induced velocity of the slipstream, realizing the coupled aerodynamic modeling of the propeller and wing. Secondly, the coupled modelling of propellers and the nonlinear structure is achieved through the derivation and transformation of the coordinate system in the co-rotation method. Finally, combined with the space beam spline, a nonlinear static aeroelastic analysis framework for the large flexible wing considering the effects of distributed propellers is established. The simulation example of flexible wing with distributed propellers shows that the propeller pull will cause negative twisting of the wing due to large deformations, resulting in approximately 10% loss of lift and 20%-40% decrease in static stability margin; the propeller slipstream will change the local flow velocity and the angle of attack, bringing about 2.5% lift gain and 2%-8% increase in static stability margin; propellers increase lift when it is close to the wing root, but decrease when close to the wing tip, and the closer to the wing tip, the more significant the effect is. The analysis method established in this paper can provide guidance for the coupling design of distributed propellers and large flexible wings.
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Kosushkin, K. G., B. S. Kritsky, and R. M. Mirgazov. "Computational studies of the rotors aerodynamic characteristics of multirotor drones." Civil Aviation High Technologies 24, no. 5 (2021): 60–75. http://dx.doi.org/10.26467/2079-0619-2021-24-5-60-75.

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The article presents the results of computational studies of aerodynamic characteristics for unmanned lift-generating multi-rotor drones of various configurations. The distinctive features of rotors flow were characterized. The rotor interaction was evaluated. The computations were based on the nonlinear rotor blade vortex theory in a non-stationary arrangement. The combinations of four, eight (four coaxial) and fourteen two-bladed rotors at velocity V = 100, 150, 200 km/h were considered. Semi-empirical methods were employed to select the rotor angles of attack, rotation speed, blade installation angles and geometric parameters at the given take-off weight for each combination of rotors and flight airspeed. The computations showed that for a four-rotor lift-generating design (quad-rotor), two rotors installed downstream, depending on the velocity due to the mutual effect, have values of the thrust coefficients ≈10...20% less than those of the rotors located upstream. For a coaxial quad-copter, the effect of the upper front rotor on the upper rear rotor is similar to the effect of the front rotors on the rear ones in a four-rotor lift-generating design. The effect of the upper front rotor on the lower rear rotor does not vary in terms of the average thrust value, and variations are only local in nature. The interaction of other rotors is identical to that of the four-rotor version. A fourteen-rotor lift-generating multi-rotor drone has a complex flow pattern, which generates deviance in the thrust coefficients variation with respect to time. Depending on the mode and rotors location, the average rotor thrust coefficient can vary approximately twice. The computations showed that with the similar geometric parameters and kinematics characteristics, rotors thrust is substantially subject to variation, which causes destabilizing moments to a significant degree without additional control input. Thrust pulsations and, respectively, vibrations grow in intensity as the flight airspeed increases. Probably, the right choice of the rotor configuration and the automatic control system can counterbalance thrust surge by so-called "phasing", i.e. selecting an initial azimuth angle for each rotor.
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Liu, Shangdong, Xi Xu, Musen Wang, et al. "FLGQM: Robust Federated Learning Based on Geometric and Qualitative Metrics." Applied Sciences 14, no. 1 (2023): 351. http://dx.doi.org/10.3390/app14010351.

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Federated learning is a distributed learning method that seeks to train a shared global model by aggregating contributions from multiple clients. This method ensures that each client’s local data are not shared with others. However, research has revealed that federated learning is vulnerable to poisoning attacks launched by compromised or malicious clients. Many defense mechanisms have been proposed to mitigate the impact of poisoning attacks, but there are still some limitations and challenges. The defense methods are either performing malicious model removal from the geometric perspective to measure the geometric direction of the model or adding an additional dataset to the server for verifying local models. The former is prone to failure when facing advanced poisoning attacks, while the latter goes against the original intention of federated learning as it requires an independent dataset; thus, both of these defense methods have some limitations. To solve the above problems, we propose a robust federated learning method based on geometric and qualitative metrics (FLGQM). Specifically, FLGQM aims to metricize local models in both geometric and qualitative aspects for comprehensive defense. Firstly, FLGQM evaluates all local models from both direction and size aspects based on similarity calculated by cosine and the Euclidean distance, which we refer to as geometric metrics. Next, we introduce a union client set to assess the quality of all local models by utilizing the union client’s local dataset, referred to as quality metrics. By combining the results of these two metrics, FLGQM is able to use information from multiple views for accurate poisoning attack identification. We conducted experimental evaluations of FLGQM using the MNIST and CIFAR-10 datasets. The experimental results demonstrate that, under different kinds of poisoning attacks, FLGQM can achieve similar performance to FedAvg in non-adversarial environments. Therefore, FLGQM has better robustness and poisoning attack defense performance.
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Zhang, Zheng Bao, and Chao Jia. "Digital Image Zero-Watermarking Algorithm Based on Improved Wavelet Moment." Applied Mechanics and Materials 347-350 (August 2013): 3232–36. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.3232.

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Lots of anti-RST attacks watermarking algorithms have been proposed, but few solutions for local geometric attacks, in this paper it proposed a new algorithm combined with the the Wavelet Moment for an anti-geometric attacks. Since wavelet moment was proposed, it is widely used in the field of computer vision, image processing, but the large amount of computation must be improved to be applied to digital watermarking technology so that it can adapt to the real-time detection of digital watermarking. By image rotation, scaling, translation, shear, local distortions, filtering attack operations and so on, these attacks can be seen that the algorithm has good robustness, and the efficiency of watermark detection is relatively high. The experiments show that the algorithm is robustness, greatly accelerate the speed of operation, to unify the robust and efficient.
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Jia, Yichen, Mingmin Ding, Libin Wang, Bin Luo, and Yangjie Ruan. "A Comparative Study on the Stability Performance of the Suspen-Dome, Conventional Cable Dome, and Ridge-Beam Cable Dome." Buildings 13, no. 8 (2023): 2019. http://dx.doi.org/10.3390/buildings13082019.

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Stability calculation is the main objective during the analysis of domes. To investigate the effects of the initial defect, geometric nonlinearity, and material nonlinearity on the stability performance of different dome structures, 60 m numerical models were built and optimized by an iterative force-finding APDL program. Then, linear buckling analysis, geometric nonlinear stability analysis, geometric nonlinear stability analysis with initial defects, and dual nonlinear analysis with initial defects were discussed to compare the stability performance of ridge-beam cable domes (RCDs), suspen-domes, and conventional cable domes via finite element analysis. The results show that the buckling loads all follow the order of initial defect + dual nonlinear analysis < initial defect + geometric nonlinear analysis < geometric nonlinear analysis < linear buckling. The addition of ridge beams improves the overall stability and transforms the instability modes from local concave instability to overall torsional buckling. The ultimate load amplification coefficients of the RCD are close to those of the suspen-dome, while the vertical displacements of the RCD are more than those of the conventional cable dome, so the RCD has sufficient stiffness to reduce local displacement. Under 2–3 load combinations, internal ridge beams change from a tensile-bending state to a compressive-bending state, causing the entire instability of the RCD afterwards.
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Zhu, Dan Dan, Xiu Ping Zhang, You Liang Zhang, and Jun Bo Dai. "A New Image Watermarking Algorithm Using NSCT and Harris Detector in Green Manufacturing." Applied Mechanics and Materials 340 (July 2013): 277–82. http://dx.doi.org/10.4028/www.scientific.net/amm.340.277.

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Based on multistage theory and NSCT, a new feature-based image watermarking scheme is proposed in this paper. Firstly, the multistage Harris detector is utilized to extract steady feature points from the host image; then, the local feature regions (LFR) are ascertained adaptively according to the feature scale theory, and they are scaled to a standard size; finally, the digital watermark are embedded into no subsample contour let low frequency area, in the low frequency regions made pseudo-Zernike moment calculation. Experimental results show that the proposed scheme is not only invisible and robust against common signals processing such as median filtering, sharpening, noise adding and JPEG compression et al, but also robust against the unclassified geometric attacks such as rotation, translation, scaling, row or column removal, shearing, local geometric distortion and combination attacks et al.
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Dissertations / Theses on the topic "Local nonlinear geometric attacks"

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Kzam, Aref Kalilo Lima. "Análise da instabilidade estrutural global e local pelo MEF posicional com determinação de pontos críticos na trajetória de equilíbrio." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-02032016-104333/.

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Nesta tese, apresenta-se o método dos elementos finitos posicional descrito em um referencial Lagrangiano total dedicado à análise de instabilidade de estruturas tridimensionais. Três tipos de elementos finitos são implementados e testados, a saber: os elementos de barra simples, casca e barra geral. A análise de instabilidade para o elemento de barra simples é efetuada determinando-se os pontos críticos ao longo da trajetória de equilíbrio em grandes deslocamentos. Para se determinar essas trajetórias são utilizados os algoritmos de Newton-Raphson e arc-length. Este tipo de análise é particularmente importante na definição de estruturas multi-estáveis de uso crescente na indústria mecânica e aeroespacial. Para o estudo da instabilidade empregando-se os elementos finitos de casca e barra geral realizam-se as análises para pequenos níveis de carga e deslocamentos por meio do cálculo dos autovalores e autovetores da matriz de rigidez da estrutura. Avaliam-se também as trajetórias de equilíbrio em grandes deslocamentos considerando-se pequenas imperfeições na geometria dos elementos estruturais. Quando os elementos de casca são utilizados na modelagem de perfis estruturais esbeltos surgem naturalmente modos de falha locais associados à mudança de forma da seção transversal. Com a finalidade de inserir essas mobilidades no elemento de barra geral propõem-se uma metodologia que considera os aprimoramentos na cinemática da barra. Esses aprimoramentos são tratados como parâmetros nodais generalizados e estão associadas a intensidade da mudança de forma de seção transversal, incluindo os modos de empenamento. Descreve-se originalmente uma metodologia de decomposição da matriz Hessiana usada para o cálculo dos valores e vetores próprios em pequenos deslocamentos. Essa metodologia possui importância adicional pois é utilizada na preparação e avaliação do parâmetro de carga em cinemáticas alternativas da formulação posicional. Utiliza-se o algoritmo de Lanczos na determinação das cargas e modos de falha realizando-se chamadas a biblioteca ARPACK. Os algoritmos são testados em exemplos modelados com os elementos finitos propostos. Próximo aos pontos críticos realiza-se a separação da matriz Hessiana procurando-se possíveis modos de colapso da estrutura. Além dos modos de falha globais é possível se identificar os modos de falha locais e distorcionais. O equilíbrio do sistema mecânico é garantido pelo princípio da estacionariedade da energia potencial total. Nas análises com os elementos de casca e barra geral, a solução do sistema não-linear é obtida empregando-se o método incremental iterativo de Newton-Raphson. Os aprimoramentos sugeridos nesta pesquisa são acoplados ao código computacional utilizado pelo grupo de mecânica computacional do departamento de engenharia de estruturas, onde diversas funcionalidades estão disponíveis, como análise dinâmica e não-linearidade material. Exemplos selecionados são apresentados ao longo da tese para demonstrar a eficiência dos elementos propostos e a aplicabilidade da técnica. Por fim, são realizadas comparações com estratégia de solução já consagradas, como por exemplo: o método das faixas finitas e a teoria generalizadas de vigas. Os resultados obtidos justificam as contribuições originais da presente pesquisa destacando-se a contribuição da formulação posicional ao estudo da instabilidade das estruturas.<br>This thesis presents the positional finite element method in a total Lagrangian framework dedicated to instability analysis of the three-dimensional structures. Three types of finite elements are implemented and tested, namely: truss, shells and frames. The instability analysis for truss element is computed using equilibrium path in large displacements. The critical points are computed using Newton-Raphson and arc-length algorithm. This analysis is particularly important in the definition of multi-stable and large displacements structures widely used in mechanical and aerospace industry. For shell and frame geometrically non-linear finite elements, the instability phenomenon is studied from the eigenvalues and eigenvectors analysis for small levels of loads and displacements. It is also evaluate the equilibrium trajectories for large displacements, considering small imperfections in the geometry of the structure. When using the shell elements to model the frames structures local failure modes associated with changing of the cross section shape arise. In order to consider the mobility in frame element new improvements are propose in the kinematic. These improvements are treated as generalized nodal parameters and are associated with the intensity of the cross-sectional change, including warping. The originally methodology of decomposition of the Hessian matrix are described and used for calculating eigenvalues and eigenvectors of the stiffness matrix. This methodology has additional importance because it is used in the preparation and evaluation of load parameter in kinematic alternatives of the positional formulation. The Lanczos algorithm is used to determining the loads and failure modes, through calls to ARPACK library for calculating eigenvalues and eigenvectors. The algorithms are tested on the examples modeled by proposed finite elements. Near the critical point takes place the separation of the Hessian matrix for possible identification of the failure modes. In addition to global failure methods, local and distortion failure are captured by this methodology. The balance of the mechanical system is guaranteed by the stationarity of the total potential energy principle. In the analysis using shells and frames elements the solution of the nonlinear system is calculated using the iterative incremental Newton-Raphson method. The improvements suggested in this research are coupled to the computer code used by computational mechanics group of the structures engineering department, where several features are available like dynamic and plasticity analysis. Selected examples are presented throughout the thesis to demonstrate the efficiency of the proposed elements and applicability of the technique. Finally, comparisons are carried out with already established solving strategy such as the finite strip methods and the generalized beam theory. The results justified the original contributions of this research to study of unstable structures.
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Book chapters on the topic "Local nonlinear geometric attacks"

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Crouch, P. E., and C. I. Byrnes. "Symmetries and Local Controllability." In Algebraic and Geometric Methods in Nonlinear Control Theory. Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4706-1_4.

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Reboulet, C., P. Mouyon, and C. Champetier. "About the Local Linearization of Nonlinear Systems." In Algebraic and Geometric Methods in Nonlinear Control Theory. Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4706-1_16.

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Grizzle, J. W. "Local Input-Output Decoupling of Discrete Time Nonlinear Systems." In Algebraic and Geometric Methods in Nonlinear Control Theory. Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4706-1_22.

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Reutenauer, Christophe. "The Local Realization of Generating Series of Finite Lie Rank." In Algebraic and Geometric Methods in Nonlinear Control Theory. Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4706-1_2.

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Joshi, N., and M. D. Kruskal. "A Local Asymptotic Method of Seeing the Natural Barrier of the Solutions of the Chazy Equation." In Applications of Analytic and Geometric Methods to Nonlinear Differential Equations. Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2082-1_32.

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Yabana, K., and H. Horiuchi. "Semiclassical analysis of coupled channel system with non-local interaction." In The Physics of Phase Space Nonlinear Dynamics and Chaos Geometric Quantization, and Wigner Function. Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/3-540-17894-5_368.

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"Perturbations of local isometries." In Geometric Nonlinear Functional Analysis. American Mathematical Society, 1999. http://dx.doi.org/10.1090/coll/048/15.

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BIANCHINI, ROSA MARIA. "LOCAL APPROXIMATION OF THE REACHABLE SET OF CONTROL PROCESSES." In Contemporary Trends in Nonlinear Geometric Control Theory and Its Applications. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812778079_0008.

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JOURANI, ABDERRAHIM. "NORMALITY, LOCAL CONTROLLABILITY AND NOC FOR MULTIOBJECTIVE OPTIMAL CONTROL PROBLEMS." In Contemporary Trends in Nonlinear Geometric Control Theory and Its Applications. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812778079_0014.

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Pismen, L. M. "Motion of Line Vortices." In Vortices in nonlinear Fields. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198501671.003.0005.

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Abstract U(l) topological defects in three dimensions are line vortices. Unlike a point vortex, a line vortex has a geometrical structure of its own, and its curvature plays a decisive role in its dynamics. Since the motion is related to the local geometry, it is advantageous to describe it in terms of intrinsic properties of a curve that do not depend on the choice of a coordinate system. We shall start therefore with a purely geometric description of the kinematics of curves in three-dimensional space.
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Conference papers on the topic "Local nonlinear geometric attacks"

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Yuan, Yibo, Shuyuan Shen, Songsen Yu, Delin Duan, Haojie Lv, and Huanjie Lin. "Geometric Attacks Resistant Zero-watermarking for Color Images Using Local Multi-channel Fractional-order Exponential Moments and SPM Chaos Mapping." In 2024 Asia-Pacific Conference on Image Processing, Electronics and Computers (IPEC). IEEE, 2024. http://dx.doi.org/10.1109/ipec61310.2024.00040.

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Luqman, Muhammad, Ashhad Zawar Khan, and Muhammad Arif. "Failure Mechanism of Tree-Shape Support Structures under Static and Lateral Loading." In 14th International Civil Engineering Conference. Trans Tech Publications Ltd, 2025. https://doi.org/10.4028/p-pig6ma.

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Trees' consistent shape and robust structure can withstand massive loads, which has influenced numerous architects and design engineers. Tree shape support structures are considered one of the most suitable alternatives to long-span roof-truss systems. Limited research has been undertaken on the structural efficiency of the columns with geometric subdivisions. This study investigates the Y-shape tree column's failure mechanism and damage index under static and lateral load. The variables considered are the external moment, subdivision element angle (θ), and joint failure volume of material (Vdj), investigating buckling and yielding behaviour. SAP2000 and ABAQUS are used in numerical modelling. The results revealed that when sliced half into branches, a symmetric column (prone to local buckling) switches the failure behaviour from buckling/ yielding to joint failure. Furthermore, Vdj has been found more in branches than stems, which increases with branch inclination (96.72% for θ =75o). Considering both static and lateral load simultaneously resulted in a slight reduction (less than 35 %) in total Vdj but made the areas with high-stress asymmetric, making the support structure unfunctional comparatively at lesser load. The sliced column behaved like a single beam/column element for pure lateral load. To brace tree-shaped structures, this study recommends using a triangular wedge by welding the erected branches together just above the joint with the stem, increasing the overall affected joint area and making it resilient by reducing the stress intensity. Yet numerous areas need more exploration, such as integrating nonlinear behaviour and using a multilayer multi-material system utilizing high-fidelity modelling approaches.
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Caldelli, R., A. De Rosa, R. Becarelli, and Mauro Barni. "Coping with local geometric attacks by means of optic-flow-based resynchronization for robust watermarking." In Electronic Imaging 2005, edited by Edward J. Delp III and Ping W. Wong. SPIE, 2005. http://dx.doi.org/10.1117/12.589106.

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Wang, Xq, Ricardo Perez, Gregory Phlipot, and Marc P. Mignolet. "Reduced Order Modeling with Local Enrichments for Nonlinear Geometric Vibration of a Notched Panel." In 56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. American Institute of Aeronautics and Astronautics, 2015. http://dx.doi.org/10.2514/6.2015-2054.

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Weerasinghe, Sandamal, Tamas Abraham, Tansu Alpcan, Sarah M. Erfani, Christopher Leckie, and Benjamin I. P. Rubinstein. "Closing the BIG-LID: An Effective Local Intrinsic Dimensionality Defense for Nonlinear Regression Poisoning." In Thirtieth International Joint Conference on Artificial Intelligence {IJCAI-21}. International Joint Conferences on Artificial Intelligence Organization, 2021. http://dx.doi.org/10.24963/ijcai.2021/437.

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Nonlinear regression, although widely used in engineering, financial and security applications for automated decision making, is known to be vulnerable to training data poisoning. Targeted poisoning attacks may cause learning algorithms to fit decision functions with poor predictive performance. This paper presents a new analysis of local intrinsic dimensionality (LID) of nonlinear regression under such poisoning attacks within a Stackelberg game, leading to a practical defense. After adapting a gradient-based attack on linear regression that significantly impairs prediction capabilities to nonlinear settings, we consider a multi-step unsupervised black-box defense. The first step identifies samples that have the greatest influence on the learner's validation error; we then use the theory of local intrinsic dimensionality, which reveals the degree of being an outlier of data samples, to iteratively identify poisoned samples via a generative probabilistic model, and suppress their influence on the prediction function. Empirical validation demonstrates superior performance compared to a range of recent defenses.
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Liu, Yafei, and Stelios Kyriakides. "Effect of Geometric and Material Discontinuities on the Reeling of Pipelines." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24474.

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Reeling remains one of the most efficient methods for installing pipelines offshore. The process results in plastic bending, straightening, and reverse bending to strain levels that can be as large as 2–3%. Thus, despite many years of practice, occasional failures during the reeling and unreeling process continue to take place resulting in costly disruptions and repairs. A common cause of such failures is local buckling that can precipitate fracture. This paper presents the results of a study of how discontinuities in geometry and mechanical properties can lead to buckling and failure. Large-scale nonlinear finite element models are used to simulate the reeling/unreeling of pipelines. The pipeline is modeled using shell elements and contact with the hub of the reel is treated appropriately. The elasto-plastic behavior of the steel is modeled using nonlinear kinematic hardening. Typically, a section of pipeline is taken through a winding and unwinding cycle on a reel of a given radius at a constant value of tension. Discontinuities in wall thickness and yield stress such as those that can occur at girth welds are shown to result in sharp local changes in curvature that extend over 3–4 pipe diameters accompanied by severe local straining and ovalization. The combination of these can lead to local buckling. Increase in the applied tension can reduce these at the expense of additional ovalization of the pipeline.
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Liu, Yu, and Andrew J. Dick. "Transient Wave Propagation in a Materially Nonlinear Beam." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64975.

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In this paper, the transient wave propagation in a materially nonlinear beam is studied. Based on previous research, the geometric nonlinearity can be neglected in an intermediate strain regime. An equation of motion for a cubic material nonlinearity is derived. The alternating frequency-time finite element method (AFT-FEM) is applied to the beam model. Numerical simulations are conducted. Significant nonlinear behavior is observed in the response. Depending on the local nonlinear property of the material in the intermediate strain regime, the amplitude of the wave response can be influenced. The nonlinear properties can also influence the dispersive characteristics of the intrinsically dispersive beam model.
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Ju, Jaehyung, Joshua D. Summers, John Ziegert, and Georges Fadel. "Nonlinear Elastic Constitutive Relations of Auxetic Honeycombs." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12654.

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When designing a flexible structure consisting of cellular materials, it is important to find the maximum effective strain of the cellular material resulting from the deformed cellular geometry and not leading to local cell wall failure. In this paper, a finite in-plane shear deformation of auxtic honeycombs having effective negative Poisson’s ratio is investigated over the base material’s elastic range. An analytical model of the inplane plastic failure of the cell walls is refined with finite element (FE) micromechanical analysis using periodic boundary conditions. A nonlinear constitutive relation of honeycombs is obtained from the FE micromechanics simulation and is used to define the coefficients of a hyperelastic strain energy function. Auxetic honeycombs show high shear flexibility without a severe geometric nonlinearity when compared to their regular counterparts.
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Warminski, Jerzy, and Andrzej Teter. "Nonlinear Modal Interactions of a Parametrically Excited Composite Column." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67249.

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Nonlinear dynamics of a composite column loaded by axial periodic force is presented in the paper. The simply supported channel column is made of several layers of a laminate with an general arrangement, leading to mechanical deformation couplings. A reduced model of the column is represented by a set of nonlinear equations which includes geometric nonlinear terms and parametric excitation. For the selected configuration of the composite structure parametric instability zones and vibration modes coupling occur. In contrast to isotropic materials, a modification of the reinforcing fibres layout results in a change of structure dynamic properties and a location of parametric resonance zones. Furthermore, buckling phenomenon may occur through various scenarios, by the global or local mode activation. The effect of the composite configuration on the principal parametric resonance zones is presented.
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Yang, Yue, Hong Zhang, Xiaoben Liu, et al. "Numerical Investigation on Local Thermal Buckling Behaviours of Buried Large Diameter Heating Pipeline." In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-61959.

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Abstract The urban infrastructure serves as lifelines for the normal operation and sustainable development of the city. The heating pipeline is one of the most important infrastructures of the urban lifeline system. At present, the design of directly buried heating pipeline is mainly based on the stress failure criterion. Since the large diameter directly buried heating water pipeline is subjected to high temperature and high pressure loads, the initial state of the pipeline is in an elsato-plastic state, which makes the equivalent stress yielding criterion cannot be applied in this case. However, the existing elastic-plastic buckling analysis mainly focuses on the displacement or mechanical loading conditions, there is no reliable evaluation index to represent the true limit state of the heated pipeline. In this investigation, geometric configuration scanning tests were carried out for pipes with diameter equals 1020 mm. The actual nonstraightness and ovality of pipeline were statistically analyzed. Based on the true geometric model, nonlinear finite element models for thermal buckling analysis of buried large-diameter heating pipelines were established. The yielding, buckling and failure behaviors of this kind of thin walled shell structures under temperature loads in engineering practice were analyzed. Parametric analysis was finally performed to investigate trends of pipe stress, strain and deformation with the pipe loading and pipe geometric parameters. The derived results can provide guidance for the design and safety assessment of directly buried heating pipeline.
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Reports on the topic "Local nonlinear geometric attacks"

1

Yoosef-Ghodsi, Ozkan, and Bandstra. PR-244-114501-R01 Review of Compressive Strain Capacity Assessment Methods Final Report. Pipeline Research Council International, Inc. (PRCI), 2013. http://dx.doi.org/10.55274/r0010402.

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Buried pipelines subjected to non-continuous ground movement such as frost heave, thaw settlement, slope instability and seismic movement experience high compressive strains that can cause local buckling (or wrinkling), in which the pipe wall buckles like a thin cylindrical shell in axial compression. In a strain-based design and assessment framework, excessive local buckling deformation that may cause loss of serviceability, or even pressure containment in some cases, is managed by limiting the strain demand below the strain limit. The determination of compressive strain limit is typically performed by full-scale structural testing or nonlinear finite element analysis that takes into account material and geometric non-linearity associated with the inelastic buckling of cylindrical shells. Before performing testing and numerical analysis (or when such options do not exist), empirical equations are used to estimate the strain limit. In this report a number of representative equations were evaluated by comparing strain limit predictions to full-scale test results. Work prior to this study has identified the importance of key variables that have the greatest impact on the local buckling behaviour. Examples of these variables include the diameter-to-thickness (D/t) ratio, internal pressure and shape of the stress strain curve. The evaluation focused on how existing equations address these key variables, and the performance with respect to key variables and in different ranges.
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METAL BEAMS SUSCEPTIBLE TO OUT-OF-PLANE INSTABILITY DUE TO COMBINED COMPRESSION AND BENDING WITH GEOMETRIC IMPERFECTIONS. The Hong Kong Institute of Steel Construction, 2024. https://doi.org/10.18057/ijasc.2024.20.4.10.

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The parts of the second generation of Eurocodes are continuously published. The full set of the 2nd generation of these new European standards consists of 68 parts of Eurocodes, 15 Technical Specifications and 5 Technical Reports and they will all be available in 2028. The aim of the paper is to bridge the gap concerning one of the newest and the most complex UGLI (Unique Global and Local Initial) imperfection methods. According to EN 1993-1-1:2022, ultimate limit state design checks may be carried out using methods of analysis named hereafter as M0, M1, M2, M3, M4, M5 or EM. Both Eurocodes EN 1993-1-1:2022 and EN 1999-1-1:2023 state, as an alternative that to sway and equivalent bow imperfection the new UGLI imperfection method may be employed for global and member analyses. In previous papers, plane stability was mostly investigated. The method presented in this paper enables the computing of the amplitude of the initial imperfection of elements under compression bending susceptible to out-of-plane buckling, and is a generalization of Eurocode rules, which is valid only for members under compression. This work is a continuation of a previous work by Agüero, in which the way to compute the UGLI imperfection was generalized for flexural torsional buckling due to compression and lateral torsional buckling due to bending. Some examples are presented to show the agreement with GMNIA (Geometrical material nonlinear analysis of imperfect structures), tests and proposals with codes.
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A SIMPLE METHOD FOR A RELIABLE MODELLING OF THE NONLINEAR BEHAVIOUR OF BOLTED CONNECTIONS IN STEEL LATTICE TOWERS. The Hong Kong Institute of Steel Construction, 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.6.

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The behaviour of bolted connections in steel lattice transmission line towers affects their load-bearing capacity and failure mode. Bolted connections are commonly modelled as pinned or fixed joints, but their behaviour lies between these two extremes and evolves in a nonlinear manner. Accordingly, an accurate finite element modelling of the structural response of complete steel lattice towers requires the consideration of various nonlinear phenomena involved in bolted connexions, such as bolt slippage. In this study, a practical method is proposed for the modelling of the nonlinear response of steel lattice tower connections involving one or multiple bolts. First, the local load-deformation behaviour of single-bolt lap connections is evaluated analytically depending on various geometric and material parameters and construction details. Then, the predicted nonlinear behaviour for a given configuration serves as an input to a 2D/3D numerical model of the entire assembly of plates in which the bolted joints are represented as discrete elements. For comparison purposes, an extensive experimental study comprising forty-four tests were conducted on steel plates assembled with one or two bolts. This approach is also extended to simulate the behaviour of assemblies including four bolts and the obtained results are checked against experimental datasets from the literature. The obtained results show that the proposed method can predict accurately the response of a variety of multi-bolt connections. A potential application of the strategy developed in this paper could be in the numerical modelling of full-scale steel lattice towers, particularly for a reliable estimation of the displacements.
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NUMERICAL AND THEORETICAL STUDIES ON DOUBLE STEEL PLATE COMPOSITE WALLS UNDER COMPRESSION AT LOW TEMPERATURES. The Hong Kong Institute of Steel Construction, 2021. http://dx.doi.org/10.18057/ijasc.2021.17.4.6.

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Double steel plate composite walls (DSCWs) with several unique types of connectors have been implemented to protect offshore oil exploration platforms from concentric forces caused by ice in the Arctic region. This paper investigates the compressive perfor-mance of DSCWs with interlocked J-hooks and overlapped headed studs at low temperatures ranging from 20 ℃ to -80 ℃ with nonlinear finite element models (FEMs). The intricate geometric size of the concrete, multiple interactions of the concrete with the connectors, and material nonlinearities of the concrete have been thoroughly simulated. The reasonable consistency between the results of the monotonic tests and finite element analysis (FEA) on nine DSCWs with interlocked J-hooks and seven DSCWs with overlapped headed studs indicates that the FEMs can effectively predict the compressive performance of the DSCWs at low temper-atures. On the basis of the validated FEMs, the effects of the horizontal and vertical spacing of the connectors on the compressive performance of the DSCWs are studied. Finally, theoretical models of the load-displacement curves are developed to reveal the compressive response of DSCWs at low temperatures with different types of connectors, taking into account the restraining effect of steel plates on the inner concrete and the local buckling of steel plates. Compared with previous tests and FEA, the developed theoretical models have reasonable consistency for the load-displacement curves of DSCWs at low temperatures.
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