Academic literature on the topic 'Warping deformation'
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Journal articles on the topic "Warping deformation"
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Cao, Juan, Xiaoyi Zhang, Jiannan Huang, and Yongjie Jessica Zhang. "Polygonal finite element-based content-aware image warping." Computational Visual Media 9, no. 2 (January 3, 2023): 367–83. http://dx.doi.org/10.1007/s41095-022-0283-7.
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AbstractMesh-based image warping techniques typically represent image deformation using linear functions on triangular meshes or bilinear functions on rectangular meshes. This enables simple and efficient implementation, but in turn, restricts the representation capability of the deformation, often leading to unsatisfactory warping results. We present a novel, flexible polygonal finite element (poly-FEM) method for content-aware image warping. Image deformation is represented by high-order poly-FEMs on a content-aware polygonal mesh with a cell distribution adapted to saliency information in the source image. This allows highly adaptive meshes and smoother warping with fewer degrees of freedom, thus significantly extending the flexibility and capability of the warping representation. Benefiting from the continuous formulation of image deformation, our poly-FEM warping method is able to compute the optimal image deformation by minimizing existing or even newly designed warping energies consisting of penalty terms for specific transformations. We demonstrate the versatility of the proposed poly-FEM warping method in representing different deformations and its superiority by comparing it to other existing state-of-the-art methods.
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Zhou, Maoding, Yuanhai Zhang, Pengzhen Lin, Wei Ji, and Hongmeng Huang. "Study of Practical Analysis Method for Shear Warping Deformationof Composite Box Girder with Corrugated Steel Webs." Materials 16, no. 5 (February 23, 2023): 1845. http://dx.doi.org/10.3390/ma16051845.
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Shear warping deformation is an important part of the flexural and constrained torsion analysis of composite box girder with corrugated steel webs (CBG-CSWs), which is also the main reason for the complex force analysis of box girders. A new practical theory for analyzing shear warping deformations of CBG-CSWs is presented. By introducing shear warping deflection and corresponding internal forces, the flexural deformation of CBG-CSWs is decoupled to the Euler-Bernoulli beam (EBB) flexural deformation and the shear warping deflection. On this basis, a simplified method for solving shear warping deformation using the EBB theory is proposed. According to the similarity of the governing differential equations of constrained torsion and shear warping deflection, a convenient analysis method for the constrained torsion of CBG-CSWs is derived. Based on the decoupled deformation states, a beam segment element analytical model applicable to EBB flexural deformation, shear warping deflection, and constrained torsion deformation is proposed. A variable section beam segment analysis program considering the variation of section parameters is developed for CBG-CSWs. Numerical examples of constant and variable section continuous CBG-CSWs show that the stress and deformation results obtained by the proposed method are in good agreement with the 3D finite element results, verifying the effectiveness by the proposed method. Additionally, the shear warping deformation has a great influence on the cross-sections near the concentrated load and middle supports. This impact along the beam axis decays exponentially, and the decay rate is related to the shear warping coefficient of the cross-section.
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Chen, Chang Hong, and Ying Huang. "The Pre-Twisted Thin-Walled Beam Element Stiffness Matrix Considering the Saint-Venant Warping Deformation." Advanced Materials Research 871 (December 2013): 129–34. http://dx.doi.org/10.4028/www.scientific.net/amr.871.129.
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Based on the traditional mechanical model of thin-walled straight beam, the paper makes a systematic analysis and research on the pre-twisted thin-walled beam finite element numerical model. Firstly, based on the geometric deformation differential relationship, the paper deduces the pre-twisted thin-walled beam Saint-Venant warping strain. According to traditional thin-walled straight beam finite element mechanical model, the paper establishes its finite element stiffness matrix considering the Saint-Venant warping deformations. Finally, by calculating the pre-twisted elliptical section beam example, and contrasting three-dimensional solid finite element using ANSYS, the comparative analysis results show that pre-twisted thin-walled beam element stiffness matrix considering Saint-Venant warping deformation has good accuracy.
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Qin, Qin, Zu-huai Wu, Yong Zang, Ben Guan, and Jinxin Zhang. "Warping deformation of 316l/q345r stainless composite plate after removal strake." World Journal of Engineering 13, no. 3 (June 13, 2016): 206–9. http://dx.doi.org/10.1108/wje-06-2016-027.
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Purpose This study aims to reduce the warping deformation of the stainless composite plate after removal strake by using a finite element method. A three-dimensional thermo-mechanical coupled elastic-plastic finite element model has been suggested by using ABAQUS to simulate the multi-pass hot rolling of stainless composite plate. Design/methodology/approach A three-dimensional thermo-mechanical coupled elastic-plastic finite element model has been suggested by using ABAQUS to simulate the multi-pass hot rolling of stainless composite plate. Warping deformation rules of 316L/Q345R stainless composite plate after removal strake have been analyzed. Moreover, the influences of some different rolling parameters on this deformation have been discussed. Findings The warping deformation just varies in the range of cladding ratio from 0.1 to 0.25. Therefore, cladding ratio does not have a great influence on warping deformation. Originality/value The results show that higher heating temperature, larger final thickness and less rolling passes are beneficial for reducing the warping deformation.
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Siddiqui, A. H., and S. F. Ng. "Effect of diaphragms on stress reduction in box girder bridge sections." Canadian Journal of Civil Engineering 15, no. 1 (February 1, 1988): 127–35. http://dx.doi.org/10.1139/l88-014.
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The purpose of this study is to examine the effect of rigid diaphragms in reducing warping and distortion stresses developed in box girders due to deformation of the cross section. Tests were conducted for two Plexiglas box girder models to determine effect of diaphragms on the behaviour of box girder sections. The results of the tests were compared with values obtained from the so-called “beam on elastic foundation (BEF) analogy,” an analytical procedure that permits the calculation of warping and distortion stresses in box sections due to deformation of the cross section.Each box girder model was tested as a simply supported beam with a 1168.4 mm (46 in.) span. Six separate loading positions were used for each of the three predesigned diaphragm spacings. Thus, 18 separate loading tests were conducted for each model in order to obtain sufficient data to determine the amount of reduction in both warping and distortion stresses. Test measurements included the applied load, deflections, and strains at various locations on the webs and bottom flanges.The results indicate that deformation of a box girder cross section due to eccentric loading may cause substantial warping and distortion stresses, and that these stresses can be effectively controlled by judicious installation of rigid diaphragms along the span of the girder. Also, experimental warping and distortion stresses obtained from both tests compare reasonably well with those predicted by the BEF analogy. Key words: warping, torsional, stresses, deformations, box girder bridges, diaphragms.
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Kim, J. H., and Y. Y. Kim. "Thin-Walled Multicell Beam Analysis for Coupled Torsion, Distortion, and Warping Deformations." Journal of Applied Mechanics 68, no. 2 (October 4, 2000): 260–69. http://dx.doi.org/10.1115/1.1357166.
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Due to the complicated deformations occurring in thin-walled multicell beams, no satisfactory one-dimensional beam theory useful for general quadrilateral multicells appears available. In this paper, we present a new systematic approach to analyze the coupled deformations of torsion, distortion, and the related warping. To develop a one-dimensional thin-walled multicell beam theory, the method to determine the section deformation functions associated with distortion and distortional warping is newly developed. In order to guarantee the singlevaluedness of the distortional warping function in multicells, distortional shear flows have been utilized. The superior result by the present one-dimensional theory is demonstrated with various examples.
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Xu, Hao, Qi Zhou, Lei Yang, Minjing Liu, Dongyue Gao, Zhanjun Wu, and Maosen Cao. "Reconstruction of full-field complex deformed shapes of thin-walled special-section beam structures based on in situ strain measurement." Advances in Structural Engineering 23, no. 15 (July 4, 2020): 3335–50. http://dx.doi.org/10.1177/1369433220937156.
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This study proposed a method capable of reconstructing complex deformations of thin-walled special-section beam structures subjected to highly coupled loading cases, in terms of the combination of tension/compression, biaxial bending, and warping torsion. The complex beam deformation was decoupled, depending on axial strain measurement strategy on beam surface, and leads to reconstructed full-field displacements (deformed shapes) as the linear superposition of deformations subject to individual loading types. Full-filed strain/stress distributions can then be derived based on the reconstructed displacements. Particular efforts were focused on reconstructing beam deformation subject to warping torsion, where both rotations angles and warping displacements across the beam cross-section and along the beam length were identified precisely. As a proof-of-concept validation, the effectiveness of the method was examined using finite element analysis, where the deformed shape of a thin-walled hat-section beam under the coupling between uniaxial bending and warping torsion was reconstructed., Experiments were conducted subsequently to reconstruct deformation of an aluminum hat-section beam using distributed optical fiber sensors for the measurement of axial strains on the beam surface. The reconstructed full-field deformed shapes of the beam were compared with the three-dimensional displacement signals captured using a non-contact digital image correlation system. The effectiveness of the proposed methodology for complex deformation reconstruction is possible to be extended to a variety of thin-walled beam-type structures which are typical in civil and aerospace engineering, showing potential contributions in fields such as on-line structural health monitoring and active structural control.
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Song, Donghwan, Adrian Matias Chung Baek, Jageon Koo, Moise Busogi, and Namhun Kim. "Forecasting Warping Deformation Using Multivariate Thermal Time Series and K-Nearest Neighbors in Fused Deposition Modeling." Applied Sciences 10, no. 24 (December 15, 2020): 8951. http://dx.doi.org/10.3390/app10248951.
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Over the past decades, additive manufacturing has rapidly advanced due to its advantages in enabling diverse material usage and complex design production. Nevertheless, the technology has limitations in terms of quality, as printed products are sometimes different from their desired designs or are inconsistent due to defects. Warping deformation, a defect involving layer shrinkage induced by the thermal residual stress generated during manufacturing processes, is a major factor in lowering the quality and raising the cost of printed products. This study utilized a variety of thermal time series data and the K-nearest neighbors (KNN) algorithm with dynamic time warping (DTW) to detect and predict the warping deformation in the printed parts using fused deposition modeling (FDM) printers. Multivariate thermal time series data extracted from thermocouples were trained using DTW-based KNN to classify warping deformation. The results showed that the proposed approach can predict warping deformation with an accuracy of over 80% by only using thermal time series data corresponding to 20% of the whole printing process. Additionally, the classification accuracy exhibited the promising potential of the proposed approach in warping prediction and in actual manufacturing processes, so the additional time and cost resulting from defective processes can be reduced.
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HASSIS, H. "A “WARPING-KIRCHHOFF” AND A “WARPING-MINDLIN” THEORY OF SHELL DEFORMATION." Journal of Sound and Vibration 225, no. 4 (August 1999): 633–53. http://dx.doi.org/10.1006/jsvi.1999.2269.
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Hassis, Hedi. "A ‘warping’ theory of plate deformation." European Journal of Mechanics - A/Solids 17, no. 5 (September 1998): 843–53. http://dx.doi.org/10.1016/s0997-7538(98)80008-9.
Full textDissertations / Theses on the topic "Warping deformation"
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Phe, Pham Van. "Stress-Deformation Theories for the Analysis of Steel Beams Reinforced with GFRP Plates." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30242.
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A theory is developed for the analysis of composite systems consisting of steel wide flange sections reinforced with GFRP plates connected to one of the flanges through a layer of adhesive. The theory is based on an extension of the Gjelsvik theory and thus incorporates local and global warping effects but omits shear deformation effects. The theory captures the longitudinal transverse response through a system of three coupled differential equations of equilibrium and the lateral-torsional response through another system of three coupled differential equations. Closed form solutions are developed and a super-convergent finite element is formulated based under the new theory.
A comparison to 3D FEA results based on established solid elements in Abaqus demonstrates the validity of the theory when predicting the longitudinal-transverse response, but showcases its shortcomings in predicting the torsional response of the composite system. The comparison sheds valuable insight on means of improving the theory.
A more advanced theory is subsequently developed based on enriched kinematics which incorporates shear deformation effects. The shear deformable theory captures the longitudinal-transverse response through a system of four coupled differential equations of equilibrium and the lateral-torsional response through another system of six coupled differential equations.
A finite difference approximation is developed for the new theory and a new finite element formulation is subsequently to solve the new system of equations. A comparison to 3D FEA illustrates the validity of the shear deformable theory in predicting the longitudinal-transverse response as well as the lateral-torsional response.
Both theories are shown to be computationally efficient and reduce the modelling and running time from several hours per run to a few minutes or seconds while capturing the essential features of the response of the composite system.
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Pezeshky, Payam. "Distortional Static and Buckling Analysis of Wide Flange Steel Beams." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36074.
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Existing design provisions in design standards and conventional analysis methods for structural steel members are based on the simplifying kinematic Vlasov assumption that neglects cross-sectional distortional effects. While the non-distortional assumption can lead to reasonable predictions of beam static response and buckling strength in common situations, past work has shown the inadequacy of such assumption in a number of situations where it may lead to over-predicting the strength of the members. The present study thus develops a series of generalized theories/solutions for the static analysis and buckling analysis of steel members with wide flange cross-sections that capture distortional effects of the web. Rather than adopting the classical Vlasov assumption that postulates the cross-section to move and rotate in its own plane as a rigid disk, the present theories assume the web to be flexible in the plane of the cross-section and thus able to bend laterally, while both flanges to move as rigid plates within the plane of the cross-section to be treated as Euler-Bernouilli beams. The theories capture shear deformation effects in the web, as well as local and global warping effects.
Based on the principle of minimum potential energy, a distortional theory is developed for the static analysis of wide flange steel beams with mono-symmetric cross-sections. The theory leads to two systems of differential equations of equilibrium. The first system consists of three coupled equilibrium differential equations that characterize the longitudinal-transverse response of the beam and the second system involves four coupled equilibrium differential equations of equilibrium and characterizes the lateral-torsional response of the beam. Closed form solutions are developed for both systems for general loading. Based on the kinematics of the new theory, two distortional finite elements are then developed. In the first element, linear and cubic Hermitian polynomials are employed to interpolate displacement fields while in the second element, the closed-form solutions developed are adopted to formulate special shape functions. For longitudinal-transverse response the elements consist of two nodes with four degree of freedom per node for longitudinal-transverse response and for lateral-torsional response, the elements consist of two nodes with eight degrees of freedom per node. The solution is able to predict the distortional deformation and stresses in a manner similar to shell solutions while keeping the modeling and computational effort to a minimum.
Applications of the new beam theory include (1) providing new insights on the response of steel beams under torsion whereby the top and bottom flanges may exhibit different angles of twist, (2) capturing the response of steel beams with a single restrained flange as may be the case when a concrete slab provides lateral and/or torsional restraint to the top flange of a steel beam, and (3) modelling the beneficial effect of transverse stiffeners in reducing distortional effects in the web.
The second part of the study develops a unified lateral torsional buckling finite element formulation for the analysis of beams with wide flange doubly symmetric cross-sections. The solution captures several non-conventional features. These include the softening effect due to web distortion, the stiffening effect induced by pre-buckling deformations, the pre-buckling nonlinear interaction between strong axis moments and axial forces, the contribution of pre-buckling shear deformation effects within the plane of the web, the destabilizing effects due to transverse loads being offset from the shear centre, and the presence of transverse stiffeners on web distortion. Within the framework of the present theory, it is possible to evoke or suppress any combination of the features and thus isolate the individual contribution of each effect or quantify the combined contributions of multiple effects on the member lateral torsional capacity. The new solution is then applied to investigate the influence of the ratios of beam span-to-depth, flange width-to-thickness, web height-to-thickness, and flange width-to-web height on the lateral torsional buckling strength of simply supported beams and cantilevers. Comparisons with conventional lateral torsional buckling solutions that omit distortional and pre-buckling effects quantify the influence of distortional and/or pre-buckling deformation effects. The theory is also used to investigate the influence of P-delta effects of beam-columns subjected to transverse and axial forces on their lateral torsional buckling resistance. The theory is used to investigate the load height effect relative to the shear centre. Comparisons are made with load height effects as predicted by non-distortional buckling theories. The solution is adopted to quantify the beneficial effect of transverse stiffeners in controlling/suppressing web distortion in beams and increasing their buckling resistance.
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Capdevielle, Sophie. "Introduction du gauchissement dans les éléments finis multifibres pour la modélisation non linéaire des structures en béton armé." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI109/document.
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Les travaux présentés dans cette thèse sont consacrés à l'enrichissement de la méthode de modélisation par éléments finis de type poutre multifibre. La méthode a fait ses preuves pour le calcul dynamique d'éléments de structures élancés, lorsque les contraintes normales prédominent. Toutefois, lorsque les contraintes de cisaillement sont prépondérantes, l'approximation de la cinématique utilisée par les éléments poutre n'est plus assez précise pour obtenir des résultats satisfaisants. L'objet de ces travaux de thèse est d'améliorer la méthode en créant un nouvel élément permettant de tenir compte du gauchissement des sections transversales dû au cisaillement. Ce développement est réalisé en deux étapes. Les éléments sont enrichis dans un premier temps par les déformations de gauchissement sous sollicitation de torsion. Le modèle de gauchissement est validé dans le domaine linéaire par confrontation aux résultats d'une modélisation numérique 3D. Après implémentation du gauchissement de torsion dans l'élément multifibre, des simulations numériques de poutres en torsion pure sont comparées à des résultats d'essais, permettant de valider le comportement des éléments poutre dans les domaines linéaire et non linéaire. Un modèle d'endommagement est utilisé pour le béton, et le gauchissement est mis à jour au fur et à mesure du calcul en tenant compte de l'évolution des propriétés matériau. L'étape suivante d'enrichissement est alors réalisée, avec l'élaboration d'un modèle de gauchissement complet sous toutes sollicitations de cisaillement, couplé au modèle d'endommagement. Une validation locale du profil de gauchissement élastique sous effort tranchant est effectuée par comparaison à la solution analytique, puis le profil de gauchissement sous sollicitations couplées de torsion et d'effort tranchant est validé par confrontation aux résultats d'une modélisation 3D. Outre la prise en compte du cisaillement par effort tranchant, la principale différence de cet enrichissement avec le modèle précédent est le calcul implicite du profil de gauchissement de la poutre au cours du calcul de structure. Les deux modèles développés sont comparés sur le comportement de poutres en torsion monotone, afin de quantifier l'impact de la méthode de calcul sur la précision des résultats et sur l'efficacité du calcul. Finalement, le modèle complet avec gauchissement est appliqué à la simulation sismique d'une structure. L'ensemble de ces cas-tests montre que l'enrichissement de la méthode par éléments finis multifibres est fonctionnel, avec des perspectives d'amélioration en ce qui concerne l'efficacité numérique notamment, et des perspectives intéressantes d'applicationThe present work is dedicated to the numerical modeling of structures using multifiber beam elements. This numerical method was proved to be efficient to simulate the behavior of slender structural elements subject to normal stresses. However, the response of the model for shear-dominating stresses lacks of accuracy. This problem is addressed by introducing warping in the kinematics of multibfiber beam elements. A new multifiber element is developed in two steps. Torsional warping is first introduced in the deformations of an arbitrary-shaped composite cross section. The resulting warping profiles are validated by comparison with the axial displacements obtained by three-dimensional modeling of beams in torsion. After implementation of the warping kinematics in a Timoshenko multifiber beam element, the formulation is validated against the experimental behavior of beams subject to pure torsion. The material is modeled by a 3D damage law, and warping is updated throughout the computations to account for damage evolution. A comparison of torque–twist curves predicted with enhanced and classical beam elements to experimental curves highlights the importance of including warping in the model. The second step consists in formulating an element with additional warping degrees of freedom, accounting for the warping deformations due to both transverse shear and torsion. This element is validated using an analytical model for a beam subject to transverse shear. Then the linear elastic behavior of a beam subject to both shear and torsion is successfully compared to the results of a 3D simulation. The complete formulation is coupled to damage through an implicit soulution procedure for the beam and the warping degrees of freedom. The enhanced method is eventually used to compute the behavior of a full structure subject to a seismic loading
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Phang, Shiau Shing. "Investigating and developing a model for iris changes under varied lighting conditions." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16672/1/Shiau_Shing_Phang_Thesis.pdf.
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Biometric identification systems have several distinct advantages over other authentication technologies, such as passwords, in reliably recognising individuals. Iris based recognition is one such biometric recognition system. Unlike other biometrics such as fingerprints or face images, the distinct aspect of the iris comes from its randomly distributed features. The patterns of these randomly distributed features on the iris have been proved to be fixed in a person's lifetime, and are stable over time for healthy eyes except for the distortions caused by the constriction and dilation of the pupil.
The distortion of the iris pattern caused by pupillary activity, which is mainly due changes in ambient lighting conditions, can be significant. One important question that arises from this is: How closely do two different iris images of the same person, taken at different times using different cameras, in different environments, and under different lighting conditions, agree with each other? It is also problematic for iris recognition systems to correctly identify a person when his/her pupil size is very different from the person's iris images, used at the time of constructing the system's data-base. To date, researchers in the field of iris recognition have made attempts to address this problem, with varying degrees of success. However, there is still a need to conduct in-depth investigations into this matter in order to arrive at more reliable solutions.
It is therefore necessary to study the behaviour of iris surface deformation caused by the change of lighting conditions. In this thesis, a study of the physiological behaviour of pupil size variation under different normal indoor lighting conditions (100 lux ~ 1,200 lux) and brightness levels is presented. The thesis also presents the results of applying Elastic Graph Matching (EGM) tracking techniques to study the mechanisms of iris surface deformation.
A study of the pupil size variation under different normal indoor lighting conditions was conducted. The study showed that the behaviour of the pupil size can be significantly different from one person to another under the same lighting conditions.
There was no evidence from this study to show that the exact pupil sizes of an individual can be determined at a given illumination level. However, the range of pupil sizes can be estimated for a range of specific lighting conditions. The range of average pupil sizes under normal indoor lighting found was between 3 mm and 4 mm.
One of the advantages of using EGM for iris surface deformation tracking is that it incorporates the benefit of the use of Gabor wavelets to encode the iris features for tracking. The tracking results showed that the radial stretch of the iris surface is nonlinear. However, the amount of extension of iris surface at any point on the iris during the stretch is approximately linear. The analyses of the tracking results also showed that the behaviour of iris surface deformation is different from one person to another. This implies that a generalised iris surface deformation model cannot be established for personal identification. However, a deformation model can be established for every individual based on their analysis result, which can be useful for personal verification using the iris.
Therefore, analysis of the tracking results of each individual was used to model iris surface deformations for that individual. The model was able to estimate the movement of a point on the iris surface at a particular pupil size. This makes it possible to estimate and construct the 2D deformed iris image of a desired pupil size from a given iris image of another different pupil size. The estimated deformed iris images were compared with their actual images for similarity, using an intensitybased (zero mean normalised cross-correlation). The result shows that 86% of the comparisons have over 65% similarity between the estimated and actual iris image. Preliminary tests of the estimated deformed iris images using an open-source iris recognition algorithm have showed an improved personal verification performance.
The studies presented in this thesis were conducted using a very small sample of iris images and therefore should not be generalised, before further investigations are conducted.
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Phang, Shiau Shing. "Investigating and developing a model for iris changes under varied lighting conditions." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16672/.
Full textAbstract:
Biometric identification systems have several distinct advantages over other authentication technologies, such as passwords, in reliably recognising individuals. Iris based recognition is one such biometric recognition system. Unlike other biometrics such as fingerprints or face images, the distinct aspect of the iris comes from its randomly distributed features. The patterns of these randomly distributed features on the iris have been proved to be fixed in a person's lifetime, and are stable over time for healthy eyes except for the distortions caused by the constriction and dilation of the pupil. The distortion of the iris pattern caused by pupillary activity, which is mainly due changes in ambient lighting conditions, can be significant. One important question that arises from this is: How closely do two different iris images of the same person, taken at different times using different cameras, in different environments, and under different lighting conditions, agree with each other? It is also problematic for iris recognition systems to correctly identify a person when his/her pupil size is very different from the person's iris images, used at the time of constructing the system's data-base. To date, researchers in the field of iris recognition have made attempts to address this problem, with varying degrees of success. However, there is still a need to conduct in-depth investigations into this matter in order to arrive at more reliable solutions. It is therefore necessary to study the behaviour of iris surface deformation caused by the change of lighting conditions. In this thesis, a study of the physiological behaviour of pupil size variation under different normal indoor lighting conditions (100 lux ~ 1,200 lux) and brightness levels is presented. The thesis also presents the results of applying Elastic Graph Matching (EGM) tracking techniques to study the mechanisms of iris surface deformation. A study of the pupil size variation under different normal indoor lighting conditions was conducted. The study showed that the behaviour of the pupil size can be significantly different from one person to another under the same lighting conditions. There was no evidence from this study to show that the exact pupil sizes of an individual can be determined at a given illumination level. However, the range of pupil sizes can be estimated for a range of specific lighting conditions. The range of average pupil sizes under normal indoor lighting found was between 3 mm and 4 mm. One of the advantages of using EGM for iris surface deformation tracking is that it incorporates the benefit of the use of Gabor wavelets to encode the iris features for tracking. The tracking results showed that the radial stretch of the iris surface is nonlinear. However, the amount of extension of iris surface at any point on the iris during the stretch is approximately linear. The analyses of the tracking results also showed that the behaviour of iris surface deformation is different from one person to another. This implies that a generalised iris surface deformation model cannot be established for personal identification. However, a deformation model can be established for every individual based on their analysis result, which can be useful for personal verification using the iris. Therefore, analysis of the tracking results of each individual was used to model iris surface deformations for that individual. The model was able to estimate the movement of a point on the iris surface at a particular pupil size. This makes it possible to estimate and construct the 2D deformed iris image of a desired pupil size from a given iris image of another different pupil size. The estimated deformed iris images were compared with their actual images for similarity, using an intensitybased (zero mean normalised cross-correlation). The result shows that 86% of the comparisons have over 65% similarity between the estimated and actual iris image. Preliminary tests of the estimated deformed iris images using an open-source iris recognition algorithm have showed an improved personal verification performance. The studies presented in this thesis were conducted using a very small sample of iris images and therefore should not be generalised, before further investigations are conducted.
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Liu, Ming. "Multidimensional damage state identification using phase space warping /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3188065.
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CAMMARANO, SANDRO. "STATIC AND DYNAMIC ANALYSIS OF HIGH-RISE BUILDINGS." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2565549.
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This thesis is focused on the structural behaviour of high-rise buildings subjected to transversal loads expressed in terms of shears and torsional moments. As horizontal reinforcement, the resistant skeleton of the construction can be composed by different vertical bracings, such as shear walls, braced frames and thin-walled open section profiles, having constant or variable geometrical properties along the height. In this way, most of the traditional structural schemes can be modelled, from moment resisting frames up to outrigger and tubular systems. In particular, an entire chapter is addressed to the case of thin-walled open section shear walls which are defined by a coupled flexural-torsional behaviour, as described by Vlasov’s theory of the sectorial areas.
From the analytical point of view, the three-dimensional formulation proposed by Al. Carpinteri and An. Carpinteri (1985) is considered and extended in order to perform dynamic analyses and encompass innovative structural solutions which can twist and taper from the bottom to the top of the building.
Such approach is based on the hypothesis of in-plane infinitely rigid floors which assure the connection between the vertical bracings and, consequently, reduce the number of degrees of freedom being only three for each level. By means of it, relevant design information such as the floor displacements, the external load distribution between the structural components, the internal actions, the free vibrations as well as the mode shapes can be quickly obtained.
The clearness and the conciseness of the matrix formulation allow to devise a simple computer program which, starting from basic information as the building geometry, the number and type of vertical stiffening, the material properties and the intensity of the external forces, provides essential results for preliminary designs.
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Baštek, Jozef. "Modelování a zobrazování pomocí blobů." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2011. http://www.nusl.cz/ntk/nusl-237054.
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This thesis deals with blobs modeling and visualizing (iso-surfaces, implicit-surfaces). It includes implementation of full-featured editor of these objects. It provides real-time operations over surfaces. The work also contains its motivation - where this modeling technique comes from, required equations and computations needed for surface rendering and algorithms used for blobs visualization.
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LU, SIANG-LING, and 盧湘玲. "An Efficient Multi-View Image Generating Method Based on Warping Deformation of Stereo Images." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3e657x.
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碩士國立宜蘭大學
資訊工程學系碩士班
105
Autostereoscopic multi-view display technology which requires 8~ 12 views, in order to present better stereo effect, but multi-view video camera which the cost is quite high, so we use software to simulate the view , and calculate its different perspective images, Depth Image Based Rendering (DIBR) is major multi-view images algorithm, due to this algorithm on the simulation perspective, it will produce an hole (disoccluded regions) in Image, although many papers to hole filling, but the effect is limited, therefore we proposed to use image Warping to calculate multi-view images, the principle is known in two left-eye view and right-eye view images, that is side by side Image, which calculated between 8~12 view by this two view , first take left-eye image to Image edge detection, to find edge points, next step to delete noise by using Douglas-Peucker algorithm, and finding corresponding right-eye image edge points by feature points, the last step to take edges points of two view images to Delaunay Triangulations, and finally calculating out 8~12 view by image warping, according to the experimental results of this paper, this algorithm calculation doesn’t create holes in image, but also to avoid the cost burden for multi-view stereoscopic technology and thinking the hole problem, would be more Efficient solution.
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TSAI, HAO-SIANG, and 蔡皓翔. "An Efficient Multi-View video Generating Method Based on Warping Deformation of Stereo Images." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/2kpa3z.
Full textAbstract:
碩士國立宜蘭大學
資訊工程學系碩士班
106
By the development of technologies, image are not only in two dimensional. In the recent years and there is a tendency to display images or videos by 3-D technology. As a result, 3D naked-eye TV is becoming more and more popular. The multi-view display technology on 3D TVs requires 8 to 12 views. In order to present a better three-dimensional effect, we need to prepare a multi-angle camera with a relatively high cost. To solve this problem, we use software to simulate the view and calculate its different perspective images. The depth image based rendering (DIBR) is currently the mainstream multi-view image algorithm. But from the point of view of the simulation, this algorithm will produce a holes in the Image, so we need to fill these holes. Although many papers are trying to overcome hole filling problem, the effect is limited and it cost too much. Therefore, we propose using Image Warping to calculate multi-view images. The principle is to generate other perspective views from the known left-eye view and right-eye view. Based on these two views, we can calculate the images side by side between the 8 to 12 views. To calculate these images ,First, make image to grayscale and surf its features. Second, remove feature points that are not strong enough, then using these features to Compute its HOG. Third, when two images are both finish these actions , then using HOG the left eye image feature can point to find the corresponding right eye image edge point. Forth ,use these points to go to Delaunay Triangulations ,and the calculates the image distortions of 8 to 12 views. Finally make up these images to make 3D video. According to the experimental results in this paper, the algorithm calculation will not cause voids in the image, it also avoids the cost burden of the multi-view stereoscopic technology, and considers the void problem, providing a more efficient solution for video.
Books on the topic "Warping deformation"
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Crush Mechanics of Thin-Walled Tubes. Taylor & Francis Group, 2016.
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Chen, Dai-heng. Crush Mechanics of Thin-Walled Tubes. Taylor & Francis Group, 2018.
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Chen, Dai-heng. Crush Mechanics of Thin-Walled Tubes. Taylor & Francis Group, 2018.
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Chen, Dai-heng. Crush Mechanics of Thin-Walled Tubes. Taylor & Francis Group, 2018.
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Chen, Dai-heng. Crush Mechanics of Thin-Walled Tubes. Taylor & Francis Group, 2018.
Find full textBook chapters on the topic "Warping deformation"
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Kim, Jibum, David McLaurin, and Suzanne M. Shontz. "A 2D Topology-Adaptive Mesh Deformation Framework for Mesh Warping." In New Challenges in Grid Generation and Adaptivity for Scientific Computing, 261–79. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-06053-8_13.
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Hu, Ningning, Yao Zhao, and Huihui Bai. "Warping and Blending Enhancement for 3D View Synthesis Based on Grid Deformation." In Lecture Notes in Computer Science, 436–44. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-71598-8_39.
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Cammarano, Sandro, Giuseppe Lacidogna, Bartolomeo Montrucchio, and Alberto Carpinteri. "Experimental Evaluation of the Warping Deformation in Thin-Walled Open Section Profiles." In Advancement of Optical Methods in Experimental Mechanics, Volume 3, 231–42. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-06986-9_26.
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Joldes, Grand Roman, Adam Wittek, Simon K. Warfield, and Karol Miller. "Performing Brain Image Warping Using the Deformation Field Predicted by a Biomechanical Model." In Computational Biomechanics for Medicine, 89–96. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-3172-5_10.
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Shama, Mohamed. "Torsion Warping Deformations and Stresses." In Torsion and Shear Stresses in Ships, 41–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14633-6_3.
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Yuille, A. L., Mario Ferraro, and Tony Zhang. "Relating image warping to 3D geometrical deformations." In Image Analysis and Processing, 361–68. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/3-540-63507-6_221.
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Miller, Michael I., Sarang C. Joshi, and Gary E. Christensen. "Large Deformation Fluid Diffeomorphisms for Landmark and Image Matching." In Brain Warping, 115–31. Elsevier, 1999. http://dx.doi.org/10.1016/b978-012692535-7/50083-5.
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Kobayashi, Shiro, Soo-Ik Oh, and Taylan Altan. "The Finite-Element Method—Part I." In Metal Forming and the Finite-Element Method. Oxford University Press, 1989. http://dx.doi.org/10.1093/oso/9780195044027.003.0009.
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The concept of the finite-element procedure may be dated back to 1943 when Courant approximated the warping function linearly in each of an assemblage of triangular elements to the St. Venant torsion problem and proceeded to formulate the problem using the principle of minimum potential energy. Similar ideas were used later by several investigators to obtain the approximate solutions to certain boundary-value problems. It was Clough who first introduced the term “finite elements” in the study of plane elasticity problems. The equivalence of this method with the well-known Ritz method was established at a later date, which made it possible to extend the applications to a broad spectrum of problems for which a variational formulation is possible. Since then numerous studies have been reported on the theory and applications of the finite-element method. In this and next chapters the finite-element formulations necessary for the deformation analysis of metal-forming processes are presented. For hot forming processes, heat transfer analysis should also be carried out as well as deformation analysis. Discretization for temperature calculations and coupling of heat transfer and deformation are discussed in Chap. 12. More detailed descriptions of the method in general and the solution techniques can be found in References [3-5], in addition to the books on the finite-element method listed in Chap. 1. The path to the solution of a problem formulated in finite-element form is described in Chap. 1 (Section 1.2). Discretization of a problem consists of the following steps: (1) describing the element, (2) setting up the element equation, and (3) assembling the element equations. Numerical analysis techniques are then applied for obtaining the solution of the global equations. The basis of the element equations and the assembling into global equations is derived in Chap. 5. The solution satisfying eq. (5.20) is obtained from the admissible velocity fields that are constructed by introducing the shape function in such a way that a continuous velocity field over each element can be denned uniquely in terms of velocities of associated nodal points.
Conference papers on the topic "Warping deformation"
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Weidong, Wang, Song Jishun, Chen Jiangping, Wang Weidong, and Wang Yuxiao. "Analysis of warping deformation of laser bracket based on moldflow." In The 2016 International Conference on Applied Engineering, Materials and Mechanics (ICAEMM 2016). WORLD SCIENTIFIC, 2016. http://dx.doi.org/10.1142/9789813146587_0031.
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Budinoff, Hannah D., Yilin Sun, and Sara McMains. "Comparison of Real-Time Geometric Analyses to Predict Warping Deformation in Fused Filament Fabrication." In ASME 2020 15th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/msec2020-8526.
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Abstract This work describes an experimental study to assess if analytical and empirical models can estimate the risk of warping deviation for parts made using fused filament fabrication based on part geometry. We also examine how the accuracy of the prediction varies for different machines and materials. If the predictive models can estimate risk of warping for a given part geometry, they can help enable better design for additive manufacturing so that designers can change part geometry early in the design process to have more easily-manufacturable parts, or choose an alternative orientation to optimize dimensional accuracy at the process planning stage. Specifically, we evaluate the extent to which two analytical models and one empirical model can assess the risk of warping for approximately rectangular parts with varying dimensions. We analyze dimensional accuracy data for parts with different length, height, and fillet type that were printed in ABS and PLA on different fused filament fabrication machines. After evaluating the three models, we found that the empirical model had the best performance over all datapoints. However, the analytical models showed promise but need further refinement on how the prediction of warping deviation depends on part height. Areas for additional research are highlighted.
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Huang, Yanping, Biaobing Huang, Hongji Xu, Dongmei Yan, and Wenpeng Li. "Moiré fringe method of using warping deformation measurement of electronic components." In 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies, edited by Tianchun Ye, Sen Han, Masaomi Kameyama, and Song Hu. SPIE, 2010. http://dx.doi.org/10.1117/12.866630.
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Kurka, Paulo R. G., Alfredo H. V. Morillo, and Thais O. de Almeida. "Dynamic Forces in a Framebraced Cargo Wagon." In 2020 Joint Rail Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/jrc2020-8070.
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Abstract This article presents a rigid bodies model of a railway wagon, with braces attached to its sideframes. The model is used to estimate the dynamic operational loads and geometric deformations of the sideframes. Yaw movements are analyzed during a curve, in the braced and unbraced conditions, showing the brace’s contribution to reduce warping deformation of the sideframes.
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Haetinger, Guilherme G., and Eduardo S. L. Gastal. "Regularized Kelvinlet Inversion for Real-Time Image Deformation and Video Time Warping." In 2020 33rd SIBGRAPI Conference on Graphics, Patterns and Images (SIBGRAPI). IEEE, 2020. http://dx.doi.org/10.1109/sibgrapi51738.2020.00025.
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Cheng, Bo, and Kevin Chou. "Deformation Evaluation of Part Overhang Configurations in Electron Beam Additive Manufacturing." In ASME 2015 International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/msec2015-9477.
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Powder-bed electron beam additive manufacturing (EBAM) has emerged as a cost-effective process for many industrial applications. Intuitively, EBAM would not require support structures for overhang geometry because the powder bed would self-support the overhang weight. However, without a proper support structure, overhang warping actually occurs in practices. In this study, a two dimensional (2D) finite element (FE) model was developed to study the thermomechanical process of EBAM. The model was applied to evaluate (1) the process parameter effect, (2) the overhang and support configuration effect, and (3) the powder porosity effect on overhang deformations. The major results are summarized as follows. (1) Increasing the beam speed and diameter will result in less deformation in an overhang area, while increasing the beam current will worsen the deformation condition. (2) A smaller tilt angle will cause a larger overhang deformation. (3) A support column, even placed away from the solid substrate side, will minimize overhang deformations. (4) An anchor-free solid piece beneath the overhang can reduce the deformation with an appropriate gap. (5) A lower powder porosity level may alleviate overhang deformations.
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Boyle, John J., Guy M. Genin, Maiko Kume, Robert B. Pless, and Stavros Thomopoulos. "Direct Optical Estimation of Deformation Gradient Tensors Using Lucas-Kanade Digital Image Warping." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14656.
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Mechanical characterization of inhomogeneous and/or geometrically complex biological tissues requires precise and accurate determination of strain fields. Digital image correlation is a well established technique for determining strain fields on the surfaces of deforming materials. The technique involves matching patterns between pairs of images to estimate the displacement of certain regions or features on a sample. 2 Image correlation has also been used to track deformations in dynamic magnetic resonance images of heart and brain. 3
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Sapountzakis, E., V. Tsipiras, and P. Gkesos. "WARPING TRANSMISSION IN 3-D BEAM ELEMENT INCLUDING SECONDARY TORSIONAL MOMENT DEFORMATION EFFECT." In 3rd South-East European Conference on Computational Mechanics. Athens: Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens (NTUA) Greece, 2014. http://dx.doi.org/10.7712/130113.4405.s2030.
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Sapountzakis, Evangelos J., Vasileios J. Tsipiras, and Pavlos G. Gkesos. "WARPING TRANSMISSION IN 3-D BEAM ELEMENT INCLUDING SECONDARY TORSIONAL MOMENT DEFORMATION EFFECT." In 3rd South-East European Conference on Computational Mechanics. Athens: ECCOMAS, 2013. http://dx.doi.org/10.7712/seeccm-2013.2030.
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Zhang, Wenjing, Yuewen Ma, and Jianmin Zheng. "Inversion Free and Topology Compatible Tetrahedral Mesh Warping Driven by Boundary Surface Deformation." In 2013 International Conference on Computer-Aided Design and Computer Graphics (CAD/Graphics). IEEE, 2013. http://dx.doi.org/10.1109/cadgraphics.2013.37.
Full textReports on the topic "Warping deformation"
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EXPERIMENTAL STUDY AND NUMERICAL ANALYSIS ON SEISMIC BEHAVIOR OF ASSEMBLED BEAM-COLUMN JOINTS WITH CSHAPED CANTILEVER SECTION (ID NUMBER: 197). The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.197.
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"A kind of assembled steel beam-column joint with C-shaped cantilever section was proposed. The influences of the lengths of cantilever sections and cover plates on seismic performance of the joints were discussed through low-cycle reciprocating loading tests and numerical simulations. Then the sensitivity analysis of key parameters such as thickness and width of flange plate ,bolt number and cover plate’s length were carried out. The results show that the joint consumed energy through warping deformations of end plate and the friction slippages between flange of beam, C-shaped cantilever section and cover plate. By reasonably increasing the lengths of C-shaped cantilevers section and cover plates, it can ensure that the joints have high bearing capacities, while significantly improving energy dissipation capacities of the joints. Parameter analysis showed that increasing thickness of the flange plate can effectively improve the stress concentration at root of the cantilever section. Reducing width of flange plate has a great impact on bearing capacity and initial stiffness of the joint with the maximum drop amplitude of 13.1% and 18.9%, respectively."