Journal articles: 'Spherical perspective'

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Kulcke, Matthias. "Spherical perspective in design education." FME Transactions 47, no. 2 (2019): 343–48. http://dx.doi.org/10.5937/fmet1902343k.

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Kovalev, A. M. "Virtual space in spherical perspective." Journal of Optical Technology 66, no. 6 (June 1, 1999): 567. http://dx.doi.org/10.1364/jot.66.000567.

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Bruvoll, Solveig, and Martin Reimers. "Spherical surface parameterization for perspective shape from shading." Pattern Recognition Letters 33, no. 1 (January 2012): 33–40. http://dx.doi.org/10.1016/j.patrec.2011.09.026.

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Jia, Hanchao, and Shigang Li. "Fast Generation of Perspective Display from Spherical Bubble." Journal of Signal Processing 18, no. 2 (2014): 111–19. http://dx.doi.org/10.2299/jsp.18.111.

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He, Ying, Suilao Li, and Qiang Guo. "Solving Perspective-n-Point Problem with Spherical Regression." IOP Conference Series: Earth and Environmental Science 234 (March 8, 2019): 012074. http://dx.doi.org/10.1088/1755-1315/234/1/012074.

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Dong, Pei Bei, and Shuo Li. "A New Spherical Triangle Graphic Method." Advanced Materials Research 557-559 (July 2012): 2134–38. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.2134.

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This Paper expounds the relation between spherical triangle and triangular pyramid in a new perspective. Thus, the graphic method to address spherical triangle problems by descriptive geometry is put forward, which broadens the research field of spherical triangle problems.

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Yulo, Paul Richard Jesena, and Heather Lyn Hendrickson. "The evolution of spherical cell shape; progress and perspective." Biochemical Society Transactions 47, no. 6 (December 12, 2019): 1621–34. http://dx.doi.org/10.1042/bst20180634.

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Bacterial cell shape is a key trait governing the extracellular and intracellular factors of bacterial life. Rod-like cell shape appears to be original which implies that the cell wall, division, and rod-like shape came together in ancient bacteria and that the myriad of shapes observed in extant bacteria have evolved from this ancestral shape. In order to understand its evolution, we must first understand how this trait is actively maintained through the construction and maintenance of the peptidoglycan cell wall. The proteins that are primarily responsible for cell shape are therefore the elements of the bacterial cytoskeleton, principally FtsZ, MreB, and the penicillin-binding proteins. MreB is particularly relevant in the transition between rod-like and spherical cell shape as it is often (but not always) lost early in the process. Here we will highlight what is known of this particular transition in cell shape and how it affects fitness before giving a brief perspective on what will be required in order to progress the field of cell shape evolution from a purely mechanistic discipline to one that has the perspective to both propose and to test reasonable hypotheses regarding the ecological drivers of cell shape change.

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Araújo, António Bandeira. "Ruler, compass, and nail: constructing a total spherical perspective." Journal of Mathematics and the Arts 12, no. 2-3 (June 26, 2018): 144–69. http://dx.doi.org/10.1080/17513472.2018.1469378.

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Zhang, Bao Feng, Ying Kui Jiao, Zhi Jun Ma, Yong Chen Li, and Jun Chao Zhu. "A Method of Features Extraction Based on Fisheye Image." Applied Mechanics and Materials 668-669 (October 2014): 1029–32. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.1029.

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In this paper, feature extraction algorithm based on spherical perspective projection model for the matching fisheye image is proposed. The fisheye image is mapped to the image plane through spherical mapping. Then the diffusion equation is formed by convolution of the image projection and spherical Gaussian function. The feature points of image are extracted based on the SIFT at the scale of spherical correlation function. Compared with SURF(Speeded Up Robust Features), more feature points in a shorter time are obtained.

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Nekoueian, Khadijeh, Mandana Amiri, Mika Sillanpää, Frank Marken, Rabah Boukherroub, and Sabine Szunerits. "Carbon-based quantum particles: an electroanalytical and biomedical perspective." Chemical Society Reviews 48, no. 15 (2019): 4281–316. http://dx.doi.org/10.1039/c8cs00445e.

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Carbon-based quantum particles, especially spherical carbon quantum dots (CQDs) and nanosheets like graphene quantum dots (GQDs), are an emerging class of quantum dots with unique properties owing to their quantum confinement effect.

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Zhu Haijiang, 祝海江, 徐晓波 Xu Xiaobo, and 周靖林 Zhou Jinglin. "Fisheye Image Matching Based on Rotation Matrix under Spherical Perspective Projection." Acta Optica Sinica 33, no. 2 (2013): 0215001. http://dx.doi.org/10.3788/aos201333.0215001.

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Xiao Xiao, 肖潇, 杨国光 Yang Guoguang, and 白剑 Bai Jian. "Panoramic-Annular-Lens Distortion Correction Based on Spherical Perspective Projection Constraint." Acta Optica Sinica 28, no. 4 (2008): 675–80. http://dx.doi.org/10.3788/aos20082804.0675.

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Maalek, Reza, and Derek D. Lichti. "Correcting the Eccentricity Error of Projected Spherical Objects in Perspective Cameras." Remote Sensing 13, no. 16 (August 18, 2021): 3269. http://dx.doi.org/10.3390/rs13163269.

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Projective transformation of spheres onto images produce ellipses, whose centers do not coincide with the projected center of the sphere. This results in an eccentricity error, which must be treated in high precision metrology. This article provides closed formulations for modeling this error in images to enable 3-dimensional (3D) reconstruction of the center of spherical objects. The article also provides a new direct robust method for detecting spherical pattern in point clouds. It was shown that the eccentricity error in an image has only one component in the direction of the major axis of the ellipse. It was also revealed that the eccentricity is zero if and only if the center of the projected sphere lies on the camera’s perspective center. The effectiveness of the robust sphere detection and the eccentricity error modeling method was evaluated on simulated point clouds of spheres and real-world images, respectively. It was observed that the proposed robust sphere fitting method outperformed the popular M-estimator sample consensus in terms of radius and center estimation accuracy by a factor of 13, and 14 on average, respectively. Using the proposed eccentricity adjustment, the estimated 3D center of the sphere using modeled eccentricity was superior to the unmodeled case. It was also observed that the accuracy of the estimated 3D center using modeled eccentricity continuously improved as the number of images increased, whereas the unmodeled eccentricity did not show improvements after eight image views. The results of the investigation show that: (i) the proposed method effectively modeled the eccentricity error, and (ii) the effects of eliminating the eccentricity error in the 3D reconstruction become even more pronounced in a larger number of image views.

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Pan, Huilin, and Kopin Liu. "Active stereo-control of the Cl + CH4(ν3 = 1) reaction: a three-dimensional perspective." Physical Chemistry Chemical Physics 22, no. 19 (2020): 10949–56. http://dx.doi.org/10.1039/d0cp01502d.

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Saura-Herreros, Miguel, Angeles Lopez, and Jose Ribelles. "Spherical panorama compositing through depth estimation." Visual Computer 37, no. 9-11 (July 18, 2021): 2809–21. http://dx.doi.org/10.1007/s00371-021-02239-7.

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AbstractIn this paper, we propose to work in the 2.5D space of the scene to facilitate composition of new spherical panoramas. For adding depths to spherical panoramas, we extend an existing method that was designed to estimate relative depths from a single perspective image through user interaction. We analyze the difficulties to interactively provide such depth information for spherical panoramas, through three different types of presentation. Then, we propose a set of basic tools to interactively manage the relative depths of the panoramas in order to obtain a composition in a very simple way. We conclude that the relative depths obtained by the extended depth estimation method are enough for the purpose of compositing new photorealistic panoramas through a few elementary editing tools.

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Duan, Ping, Jia Tian Li, and Jia Li. "Dimension-Descending Algorithm for Spherical Delaunay Triangulation." Applied Mechanics and Materials 130-134 (October 2011): 2915–19. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.2915.

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Spherical Delaunay triangulation (SDT) which is a powerful tool to represent, organize and analyze spherical space data has become a focus of spherical GIS research. Projection stitching algorithm is one of the main construction algorithms of SDT. The basic idea of stitching algorithm is that the sphere is divided into two hemispheres to avoid projected image point coincidence. So, the practicality of projection stitching algorithm is lower because of merging two hemispheres. Aimed at the disadvantage of projection stitching algorithm, this paper puts forward a new algorithm to construct SDT used perspective projection principle. The projection center is placed on sphere to establish one-to-one mapping between spherical space points and plane image points. Experiment shows that the time complexity of our algorithm depends on Delaunay triangulation construction algorithm of the plane.

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YAMADA, Tsuyoshi, Kenji HARA, Ryo KURAZUME, Yumi IWASHITA, and Tsutomu HASEGAWA. "2P2-B22 3D shape reconstruction by spherical mirror using perspective factorization method." Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2008 (2008): _2P2—B22_1—_2P2—B22_4. http://dx.doi.org/10.1299/jsmermd.2008._2p2-b22_1.

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Ben-Soussan, Tal. "Symposium Title: Motion and Emotion in Developmental Disorders: A Spherical Psychophysiological Perspective." International Journal of Psychophysiology 168 (October 2021): S6. http://dx.doi.org/10.1016/j.ijpsycho.2021.07.016.

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Gingold, Yotam I., and Harry Gingold. "SIMULATION OF PERSPECTIVE BY NONLINEAR TRANSFORMATIONS." Mathematical Modelling and Analysis 18, no. 3 (June 1, 2013): 346–57. http://dx.doi.org/10.3846/13926292.2013.804887.

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A feature of the brain processing the visualization of objects is such that objects that are much farther away from the eye look smaller than closer objects to the eye. We show that a family of nonlinear transformations, also to be called compactifications, simulate qualitatively this property of keeping objects in perspective. These transformations project objects in a plane on a spherical shell. It is shown then that an observer located at a fixed point on the axis of the sphere visualizes the projected objects on the sphere in perspective. Namely, that objects that are farther away from the observation point seem smaller. Examples are provided. This is a departure from the traditional approaches using linearity and projections of objects from one plane into another plane.

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Fan, Shuai, and Shouwen Fan. "Difference between the ideal and combined spherical joints and its effects on parallel manipulators." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 5 (November 19, 2019): 1112–29. http://dx.doi.org/10.1177/0954406219888240.

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When using parallel manipulators as machine tools, the spherical joint has been widely used and replaced by a combination of a universal joint and a rotating unit, but the introduced differences and effects have not been studied in detail. In this paper, an approach to establish the mathematical models of the ideal and combined spherical joints is presented, and the differences between the two spherical joints are given from the perspective of constraints, workspace, clearance, and contact deformation. First, the non-interference workspace of a class universal joint is investigated by using a simple and clear projection method, where the constraint domain and workspace of two spherical joints are proposed. Next, the approximate clearance models of these two spherical joints are analyzed, and the corresponding contact deformation models are also given based on the Hertzian Contact theory. Finally, a 1PU + 3UPS parallel manipulator is used to verify the discrepant effects of two spherical joints on parallel manipulators. If the combined spherical joint is used, the results indicate that the improvement in the workspace is significant, but the drop in stiffness is also evident. Thus, this paper provides a theoretical basis for researchers to use combined spherical joints.

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Boice, Daniel C., and Raymond Goldstein. "A cometary perspective of Enceladus." Proceedings of the International Astronomical Union 5, S263 (August 2009): 151–56. http://dx.doi.org/10.1017/s1743921310001675.

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AbstractIcy plumes venting from Enceladus draw obvious comparisons to such features seen in comets. This paper outlines a consistent evolution from cometary activity to larger icy bodies in the outer solar system. The major differences are due to the systematic effects of increased gravity, including more spherical solid bodies (self-gravity), less porosity, the possible existence of liquid water due to internal sources of heat (Enceladus) versus possible cometary cyrovolcanism, internal inhomogeneities leading to jet-like features, and the possibility of a quasi-bound dusty gas atmosphere, as opposed to the extensive exospheres of comets. Similarities exist also, including gas and dust emission and the filamentary nature of jet-like features (caused by surface topography in comets), surface evolution by dust accumulation, heat and gas transport through the surface layers, among others. Initial results regarding the plume chemistry and comparisons to CAPS ion data show similarities too. Others have considered additional effects such as, charging of particles, micrometeorite impacts and complex interactions with the E-ring neutrals and plasma in great detail so these topics remain outside the scope of this paper.

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Bormotova, Irina, Elena Kopteva, Mariia Churilova, and Zdenek Stuchlik. "Accelerated expansion of the universe from the perspective of inhomogeneous cosmology." International Journal of Modern Physics A 35, no. 02n03 (January 30, 2020): 2040037. http://dx.doi.org/10.1142/s0217751x20400370.

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We present a special case of the Stephani solution with spherical symmetry while considering different values of spatial curvature. We investigate the dynamics of the universe evolution in our model, build the R–T-regions for the resulting spacetime and analyze the behavior of the deceleration parameter. The singularities of the model are also discussed. The geometry of the spatial part of the obtained solution is explored.

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Bacciarini, Claudio, and Vincent Mathier. "Aluminium AA6061 Matrix Composite Reinforced with Spherical Alumina Particles Produced by Infiltration: Perspective on Aerospace Applications." Journal of Metallurgy 2014 (November 30, 2014): 1–10. http://dx.doi.org/10.1155/2014/248542.

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Metal matrix composites, based on AA6061 reinforced with 60 vol% Al2O3 spherical particles, were produced by gas pressure infiltration and characterized for hardness, impulse excitation modulus, tensile properties (at room temperature and at 250°C), and machining. It was experimentally demonstrated that the novel alumina powder used in the present work does not react with the liquid Mg-containing matrix during the infiltration process. The AA6061 matrix therefore retains its ability to be strengthened by precipitation heat treatment. The latter behaviour combined with the spherical particle shape confers the studied material higher strength and better machinability in comparison with similar composites produced using standard angular alumina particles. The overall features are promising for applications in the aerospace industry, where light and strong materials are required.

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Rajurkar, H. "AYURVEDIC PERSPECTIVE OF SUBCLINICAL HYPOTHYROIDISM." Journal of Medical pharmaceutical and allied sciences 10, no. 3 (July 15, 2021): 3046–50. http://dx.doi.org/10.22270/jmpas.v10i3.1156.

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Thyroid gland is one of the important glands of the endocrine system and thyroid disorders are the most common disorders amongst the general population worldwide, as well as in india. Hypothyroidism is caused by inadequate function of the thyroid gland called as primary hypothyroidism or by insufficient stimulation by thyroid- stimulating hormones called as secondary hypothyroidism. Current view the thyroid gland is a butterfly shaped gland. It is located inferior to the larynx and anterior to the trachea. It has two lobes connected by the isthmus. It is made of microscopic spherical masses called follicles. A secretary substance is present in the follicle called colloid. Colloid is made of a glycoprotein called as thyroglobulin. Thyroglobulin produces thyroid hormones. They are triiodothyronine (t3), tetraiodothyronine (t4) and calcitonin. Ayurvedic perspective of subclinical hypothyroidism. Management of hypothyroidism with synthetic thyroid hormone derivatives may bring the value of tsh, t3 and t4 to normal range but the daily intake of medicine for lifetime, the known side-effects thereafter and increase in the dosage with time as the disease become chronic, is troublesome for the patients. Also the quality of life of the patients taking medicine regularly for long durations is compromised.

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Zhao, Pengyu, Ansheng You, Yuanxing Zhang, Jiaying Liu, Kaigui Bian, and Yunhai Tong. "Spherical Criteria for Fast and Accurate 360° Object Detection." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 07 (April 3, 2020): 12959–66. http://dx.doi.org/10.1609/aaai.v34i07.6995.

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With the advance of omnidirectional panoramic technology, 360◦ imagery has become increasingly popular in the past few years. To better understand the 360◦ content, many works resort to the 360◦ object detection and various criteria have been proposed to bound the objects and compute the intersection-over-union (IoU) between bounding boxes based on the common equirectangular projection (ERP) or perspective projection (PSP). However, the existing 360◦ criteria are either inaccurate or inefficient for real-world scenarios. In this paper, we introduce a novel spherical criteria for fast and accurate 360◦ object detection, including both spherical bounding boxes and spherical IoU (SphIoU). Based on the spherical criteria, we propose a novel two-stage 360◦ detector, i.e., Reprojection R-CNN, by combining the advantages of both ERP and PSP, yielding efficient and accurate 360◦ object detection. To validate the design of spherical criteria and Reprojection R-CNN, we construct two unbiased synthetic datasets for training and evaluation. Experimental results reveal that compared with the existing criteria, the two-stage detector with spherical criteria achieves the best mAP results under the same inference speed, demonstrating that the spherical criteria can be more suitable for 360◦ object detection. Moreover, Reprojection R-CNN outperforms the previous state-of-the-art methods by over 30% on mAP with competitive speed, which confirms the efficiency and accuracy of the design.

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Zhang, Yutong, Jianmei Song, Yan Ding, Yating Yuan, and Hua-Liang Wei. "FSD-BRIEF: A Distorted BRIEF Descriptor for Fisheye Image Based on Spherical Perspective Model." Sensors 21, no. 5 (March 6, 2021): 1839. http://dx.doi.org/10.3390/s21051839.

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Fisheye images with a far larger Field of View (FOV) have severe radial distortion, with the result that the associated image feature matching process cannot achieve the best performance if the traditional feature descriptors are used. To address this challenge, this paper reports a novel distorted Binary Robust Independent Elementary Feature (BRIEF) descriptor for fisheye images based on a spherical perspective model. Firstly, the 3D gray centroid of feature points is designed, and the position and direction of the feature points on the spherical image are described by a constructed feature point attitude matrix. Then, based on the attitude matrix of feature points, the coordinate mapping relationship between the BRIEF descriptor template and the fisheye image is established to realize the computation associated with the distorted BRIEF descriptor. Four experiments are provided to test and verify the invariance and matching performance of the proposed descriptor for a fisheye image. The experimental results show that the proposed descriptor works well for distortion invariance and can significantly improve the matching performance in fisheye images.

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KRAMER, JOSH BROWN, and LUCAS SABALKA. "MULTIDIMENSIONAL ONLINE MOTION PLANNING FOR A SPHERICAL ROBOT." International Journal of Computational Geometry & Applications 20, no. 06 (December 2010): 653–84. http://dx.doi.org/10.1142/s0218195910003475.

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We consider three related problems of robot movement in arbitrary dimensions: coverage, search, and navigation. For each problem, a spherical robot is asked to accomplish a motion-related task in an unknown environment whose geometry is learned by the robot during navigation. The robot is assumed to have tactile and global positioning sensors. We view these problems from the perspective of (non-linear) competitiveness as defined by Gabriely and Rimon. We first show that in 3 dimensions and higher, there is no upper bound on competitiveness: every online algorithm can do arbitrarily badly compared to the optimal. We then modify the problems by assuming a fixed clearance parameter. We are able to give optimally competitive algorithms under this assumption. We show that these modified problems have polynomial competitiveness in the optimal path length, of degree equal to the dimension.

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Turmanidze, Raul, and Giorgi Popkhadze. "Selection Criteria of Optimal Characteristic Material and Technologies for Precision Processing of Basic Working Surface of Human Hip-Joint Implant." Solid State Phenomena 261 (August 2017): 28–35. http://dx.doi.org/10.4028/www.scientific.net/ssp.261.28.

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In view of the fact that the endo-prosthesis heads of human hip-joint are operated in extreme conditions, in respect of load, the selection of corresponding material and also increase of precision and quality of machining of spherical surfaces is rather topical task.In the submitted work are reviewed the problems connected with definition of the influence degree of orientation of the sapphire crystal on its workability during diamond grinding with a butt of the ring and elaboration of the perspective, original scheme of formation of the incomplete spherical surface, particularly, of the sapphire head of endo-prosthesis of the human hip-joint.

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Sarradin, François, Daniel Siret, Michel Couprie, and Jacques Teller. "Comparing Sky Shape Skeletons for the Analysis of Visual Dynamics along Routes." Environment and Planning B: Planning and Design 34, no. 5 (October 2007): 840–57. http://dx.doi.org/10.1068/b32143.

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The motion of an observer in a given space produces a particular perception called motion perspective. This has been defined by Gibson as the gradual changes in the rate of displacements of contour lines in the visual field of the observer. This paper describes a new approach intended for analysing the motion perspective in order to quantify the morphology of urban open spaces along routes. It is based on spherical projections, which provide the shape of the sky boundary around the observer. The projections are studied through their skeletons, which are continuous sets of curves obtained by a progressive thinning down of the shapes around their main saliencies. The proposed method uses these skeletons to follow the variations in the shape of the sky boundary between the successive views. Measures of these variations have been developed and applied in a range of simplified theoretical examples and a real field example in order to show that they succeeded in capturing significant variations in spherical projections.

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Sieber, Jan, John W. Hutchinson, and J. Michael T. Thompson. "Nonlinear dynamics of spherical shells buckling under step pressure." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, no. 2223 (March 2019): 20180884. http://dx.doi.org/10.1098/rspa.2018.0884.

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Dynamic buckling is addressed for complete elastic spherical shells subject to a rapidly applied step in external pressure. Insights from the perspective of nonlinear dynamics reveal essential mathematical features of the buckling phenomena. To capture the strong buckling imperfection-sensitivity, initial geometric imperfections in the form of an axisymmetric dimple at each pole are introduced. Dynamic buckling under the step pressure is related to the quasi-static buckling pressure. Both loadings produce catastrophic collapse of the shell for conditions in which the pressure is prescribed. Damping plays an important role in dynamic buckling because of the time-dependent nonlinear interaction among modes, particularly the interaction between the spherically symmetric ‘breathing’ mode and the buckling mode. In general, there is not a unique step pressure threshold separating responses associated with buckling from those that do not buckle. Instead, there exists a cascade of buckling thresholds, dependent on the damping and level of imperfection, separating pressures for which buckling occurs from those for which it does not occur. For shells with small and moderately small imperfections, the dynamic step buckling pressure can be substantially below the quasi-static buckling pressure.

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Sneeuw, Nico. "Global spherical harmonic analysis by least-squares and numerical quadrature methods in historical perspective." Geophysical Journal International 118, no. 3 (September 1994): 707–16. http://dx.doi.org/10.1111/j.1365-246x.1994.tb03995.x.

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Xu, Xian Feng, Ling Zhi Chai, Hui Li, and Ling Sheng Zeng. "Study on the Electric Properties of Carbon Fibers and its Application for the Preparation of Carbon/Carbon Composites." Materials Science Forum 809-810 (December 2014): 707–10. http://dx.doi.org/10.4028/www.scientific.net/msf.809-810.707.

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Acetylene (C2H2) was used as carbon source gas, nitrogen (N2) as dilution gas. The electric properties of carbon fibers was briefly discussed by energizing the carbon fibers in vacuum condition which were applied for the preparation of carbon/carbon composites by the method of chemical vapor deposition. The deposition mechanism and microstructure of pyrolytic carbons in carbon fibers under different deposition crafts were also discussed. Results indicate that the greater the initial voltage, the higher the temperature, we can change the deposition temperature by changing the initial voltage according to the relationship between the brightness and the surface temperature of carbon fibers. The surface of carbon fibers will be etched in the process of electrifying which would make the pyrolytic carbons preferred deposition on the etching point which became the growth center in the early deposition process. The pyrolytic carbons deposited with a spherical microcrystalline structure under the gas flow of C3H6/N2=2:3, When the rate of gas flow is C3H6/N2=1:2, The pyrolytic carbons deposited with a spherical microcrystalline structure after deposited for 0.5h, but after deposited for 1h, the deposition of large patches of molecular is dominant which lead to that: from a macro perspective, the pyrolytic carbons were a layered structure, From a microscopic perspective, they were a spherical microcrystalline structure with different size.

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Migranov, Denis I. "Some Aspects of Three-Dimensional Spherical and Elliptical Spaces Visualization." Vestnik NSU. Series: Information Technologies 18, no. 4 (2020): 54–65. http://dx.doi.org/10.25205/1818-7900-2020-18-4-54-65.

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In this paper we examine methods and algorithms for visualizing three-dimensional non-Euclidean spherical and elliptical spaces with a first-person view, from insider’s perspective: we propose an algorithm for implementing camera controls in such spaces, address an approach to visualizing properties of such spaces based on matrix and vector operations which enables us to perform some of the computations necessary for the visualization on GPUs using graphics APIs, describe an implementation of fog effects in such spaces for the purpose of simplifying navigation in them. An implementation of these approaches and algorithms that is intended for visualizing dynamic scenes in such spaces is presented.

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Turmanidze, Raul, Predrag Dašić, and Giorgi Popkhadze. "Selection criteria of optimal characteristic material and technologies for precision processing of basic working surface of human hip-joint implant." MATEC Web of Conferences 184 (2018): 01015. http://dx.doi.org/10.1051/matecconf/201818401015.

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In view of the fact that the endo-prosthesis heads of human hip-joint are operated in extreme conditions, in respect of load, the selection of corresponding material and also increase of precision and quality of machining of spherical surfaces is rather topical task. In the submitted work are reviewed the problems connected with definition of the influence degree of orientation of the sapphire crystal on its workability during diamond grinding with a butt of the ring and elaboration of the perspective, original scheme of formation of the incomplete spherical surface, particularly, of the sapphire head of endo-prosthesis of the human hip-joint.

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Lee, Hwi, and Qiang Du. "Nonlocal gradient operators with a nonspherical interaction neighborhood and their applications." ESAIM: Mathematical Modelling and Numerical Analysis 54, no. 1 (January 2020): 105–28. http://dx.doi.org/10.1051/m2an/2019053.

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Nonlocal gradient operators are prototypical nonlocal differential operators that are very important in the studies of nonlocal models. One of the simplest variational settings for such studies is the nonlocal Dirichlet energies wherein the energy densities are quadratic in the nonlocal gradients. There have been earlier studies to illuminate the link between the coercivity of the Dirichlet energies and the interaction strengths of radially symmetric kernels that constitute nonlocal gradient operators in the form of integral operators. In this work we adopt a different perspective and focus on nonlocal gradient operators with a non-spherical interaction neighborhood. We show that the truncation of the spherical interaction neighborhood to a half sphere helps making nonlocal gradient operators well-defined and the associated nonlocal Dirichlet energies coercive. These become possible, unlike the case with full spherical neighborhoods, without any extra assumption on the strengths of the kernels near the origin. We then present some applications of the nonlocal gradient operators with non-spherical interaction neighborhoods. These include nonlocal linear models in mechanics such as nonlocal isotropic linear elasticity and nonlocal Stokes equations, and a nonlocal extension of the Helmholtz decomposition.

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Yankovskaya, L. "COMPUTER GRAPHIC FORM SHAPING OF SPHERICAL OBJECTS IN DESIGN BASED ON THE PERSPECTIVE CONTOUR LINE." Modern problems of modeling 15 (June 13, 2019): 190–99. http://dx.doi.org/10.33842/2313-125x/2019/15/190/199.

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Costley, A. E. "Towards a compact spherical tokamak fusion pilot plant." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2141 (February 4, 2019): 20170439. http://dx.doi.org/10.1098/rsta.2017.0439.

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The question of size of a tokamak fusion reactor is central to current fusion research especially with the large device, ITER, under construction and even larger DEMO reactors under initial engineering design. In this paper, the question of size is addressed initially from a physics perspective. It is shown that in addition to size, field and plasma shape are important too, and shape can be a significant factor. For a spherical tokamak (ST), the elongated shape leads to significant reductions in major radius and/or field for comparable fusion performance. Further, it is shown that when the density limit is taken into account, the relationship between fusion power and fusion gain is almost independent of size, implying that relatively small, high performance reactors should be possible. In order to realize a small, high performance fusion module based on the ST, feasible solutions to several key technical challenges must be developed. These are identified and possible design solutions outlined. The results of the physics, technical and engineering studies are integrated using the Tokamak Energy system code, and the results of a scoping study are reviewed. The results indicate that a relatively small ST using high temperature superconductor magnets should be feasible and may provide an alternative, possibly faster, ‘small modular’ route to fusion power. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

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Shevchuk, Stanislav O., Elena S. Cheremisina, and Nikolay S. Kosarev. "SATELLITE NAVIGATION EQUIPMENT FOR SOLAR SYSTEM OBJECTS EXPLORATION." Interexpo GEO-Siberia 1, no. 2 (July 8, 2020): 128–39. http://dx.doi.org/10.33764/2618-981x-2020-1-2-128-139.

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The article contains the overview of perspective satellite navigation systems for other planets and objects of Solar System. The example of this conception for the Moon is considered. The paper contains the brief overview of Moon exploration perspectives. An overview of countries’ space agencies programs on the Moon with automatic and human missions. The problem of lunar and cislunar navigation is considered, the ways of its solution are overviewed. One of the possible cases for lunar and cislunar navigation system realization is to create the satellite system similar to the Earth’s GNSS using the existing experiences. The main goal of the article is the conception of lunar receiver designed for the lunar navigation satellite system in case it is similar to GLONASS. The formulas’ simplifications because of Moon’s features are considered, including: absence of atmosphere and as a result absence of ionospheric and tropospheric delays; more simple gravity field because of small flattering (almost spherical shape). The conclusions on perspectives of the lunar navigation are made.

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Ilizirov, Grigory, and Sagi Filin. "POSE ESTIMATION AND MAPPING USING CATADIOPTRIC CAMERAS WITH SPHERICAL MIRRORS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 43–47. http://dx.doi.org/10.5194/isprsarchives-xli-b3-43-2016.

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Catadioptric cameras have the advantage of broadening the field of view and revealing otherwise occluded object parts. However, they differ geometrically from standard central perspective cameras because of light reflection from the mirror surface which alters the collinearity relation and introduces severe non-linear distortions of the imaged scene. Accommodating for these features, we present in this paper a novel modeling for pose estimation and reconstruction while imaging through spherical mirrors. We derive a closed-form equivalent to the collinearity principle via which we estimate the system’s parameters. Our model yields a resection-like solution which can be developed into a linear one. We show that accurate estimates can be derived with only a small set of control points. Analysis shows that control configuration in the orientation scheme is rather flexible and that high levels of accuracy can be reached in both pose estimation and mapping. Clearly, the ability to model objects which fall outside of the immediate camera field-of-view offers an appealing means to supplement 3-D reconstruction and modeling.

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Ilizirov, Grigory, and Sagi Filin. "POSE ESTIMATION AND MAPPING USING CATADIOPTRIC CAMERAS WITH SPHERICAL MIRRORS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B3 (June 9, 2016): 43–47. http://dx.doi.org/10.5194/isprs-archives-xli-b3-43-2016.

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Catadioptric cameras have the advantage of broadening the field of view and revealing otherwise occluded object parts. However, they differ geometrically from standard central perspective cameras because of light reflection from the mirror surface which alters the collinearity relation and introduces severe non-linear distortions of the imaged scene. Accommodating for these features, we present in this paper a novel modeling for pose estimation and reconstruction while imaging through spherical mirrors. We derive a closed-form equivalent to the collinearity principle via which we estimate the system’s parameters. Our model yields a resection-like solution which can be developed into a linear one. We show that accurate estimates can be derived with only a small set of control points. Analysis shows that control configuration in the orientation scheme is rather flexible and that high levels of accuracy can be reached in both pose estimation and mapping. Clearly, the ability to model objects which fall outside of the immediate camera field-of-view offers an appealing means to supplement 3-D reconstruction and modeling.

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KRISTEN, U., J. LOCKHAUSEN, W. MENHARDT, and W. J. DALLAS. "Computer-generated three-dimensional representation of dictyosomes reconstructed from electron micrographs of serial ultrathin sections." Journal of Cell Science 93, no. 2 (June 1, 1989): 385–89. http://dx.doi.org/10.1242/jcs.93.2.385.

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Computer-generated three-dimensional reconstructions of higher plant dictyosomes from electron micrographs are presented from different viewing angles in the form of shaded perspective displays. The image processing has revealed complicated structures indicating a central cisternal stack surrounded by a cloud of vesicles and vesicular and tubular protrusions. The entire dictyosome is suggested as being an approximately spherical body that is marginally penetrated by plates and tubules of the endoplasmic reticulum.

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Filin, Sagi, Grigory Ilizirov, and Bashar Elnashef. "Robust Pose Estimation and Calibration of Catadioptric Cameras With Spherical Mirrors." Photogrammetric Engineering & Remote Sensing 86, no. 1 (January 1, 2020): 33–44. http://dx.doi.org/10.14358/pers.86.1.33.

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Catadioptric cameras broaden the field of view and reveal otherwise occluded object parts. They differ geometrically from central-perspective cameras because of light reflection from the mirror surface. To handle these effects, we present new pose-estimation and reconstruction models for imaging through spherical mirrors. We derive a closed-form equivalent to the collinearity principle via which three methods are established to estimate the system parameters: a resection-based one, a trilateration-based one that introduces novel constraints that enhance accuracy, and a direct and linear transform-based one. The estimated system parameters exhibit improved accuracy compared to the state of the art, and analysis shows intrinsic robustness to the presence of a high fraction of outliers. We then show that 3D point reconstruction can be performed at accurate levels. Thus, we provide an in-depth look into the geometrical modeling of spherical catadioptric systems and practical enhancements of accuracies and requirements to reach them.

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Bagade, Om M., Shashikant N. Dhole, and Praveen D. Chaudhar. "A Corollary of Nanoporous Carrier Drug Delivery System: An Updated Perspective." International Journal of Pharmaceutical Sciences and Nanotechnology 13, no. 5 (September 15, 2020): 5047–61. http://dx.doi.org/10.37285/ijpsn.2020.13.5.1.

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Nanosponges have come into sight as one of the most promising fields of science because of their perceived applications in controlled drug delivery. It has been increasingly investigated to achieve targeted and sustained release of drugs. Nanosponges are one of the novel drug delivery system, which is gaining popularity now days because of their perceived application in controlled and site-specific drug delivery. The fundamental appeal of the nanosponge technology arises from the difficulty experienced with conventional formulations in releasing active ingredients over an extended period of time, unpleasant odor, greasiness and skin irritation. They are tiny sponge-like spherical particles with a large porous surface and are believed to contribute towards reduced side effects, improved stability, increased elegance and enhanced formulation flexibility. The present investigation in the appraisal describes nanosponge technology embracing its method of preparation, characterization, in-vitro and in-vivo evaluation methods along with recent research and future potential.

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Zhang, Le-Wen, Jing Wu, and Da-Liang Zhang. "Shape Optimization and Stability Analysis for Kiewitt Spherical Reticulated Shell of Triangular Pyramid System." Mathematical Problems in Engineering 2019 (July 18, 2019): 1–11. http://dx.doi.org/10.1155/2019/2723082.

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The Kiewitt spherical reticulated shell of triangular pyramid system is taken as the object of this study; a macroprogram of parametric modeling is developed by using the ANSYS Parametric Design Language. The minimum structural total weight is taken as the objective function, and a shape optimization program is proposed and compiled by adopting the sequence two-stage algorithm in FORTRAN environment. Then, the eigenvalue buckling analysis for Kiewitt spherical reticulated shell of triangular pyramid system is carried out with the span of 90 m and rise-span ratio of 1/7~1/3. On this basis, the whole nonlinear buckling process of the structure is researched by considering initial geometrical imperfection. The load-displacement curves are drawn, and the nonlinear behaviors of special nodes are analyzed. The structural nonlinear behaviors affected by rise-span ratio are discussed. Finally, the stability of reticulated shell before and after optimization is compared. The research results show that (1) users can easily get the required models only by inputting five parameters, i.e., the shell span (S), rise (F), latitudinal portions (Kn), radial loops (Nx), and thickness (T). (2) Under the conditions of different span and rise-span ratio, the optimal grid number and bar section for the Kiewitt spherical reticulated shell of triangular pyramid system existed after optimization; i.e., the structural total weight is the lightest. (3) The whole rigidity and stability of the Kiewitt spherical reticulated shell of triangular pyramid system are very nice, and the reticulated shell after optimization can still meet the stability requirement. (4) When conducting the reticulated shell design, the structural stability and carrying capacity can be improved by increasing the rise-span ratio or the rise. (5) From the perspective of stability, the rise-span ratio of the Kiewitt spherical reticulated shell of triangular pyramid system should not choose 1/7.

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Teller, Jacques. "A Spherical Metric for the Field-Oriented Analysis of Complex Urban Open Spaces." Environment and Planning B: Planning and Design 30, no. 3 (June 2003): 339–56. http://dx.doi.org/10.1068/b12930.

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The author deals with the analysis of urban open spaces, once conceived as part and parcel of our urban heritage. He introduces a mathematical modelling technique that is capable of mapping the variation of the sky visible from points distributed throughout space. The resulting maps overcome the limits of orthographic (plan, section, and elevation) and perspective methods of analysis by considering the dynamic qualities of the Gibsonian ‘visual world’ that takes account not only of bifocal vision but also of the relatively free movement of the head and shoulders, that is, vision as part of the human ecology. The maps show how a person might experience those volumes of a void that define a space, not from a fixed point but from moving about inside the entire urban open space.

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Dodero, Andrea, Maila Castellano, Paola Lova, Massimo Ottonelli, Elisabetta Brunengo, Silvia Vicini, and Marina Alloisio. "Composite Poly(vinyl alcohol)-Based Nanofibers Embedding Differently-Shaped Gold Nanoparticles: Preparation and Characterization." Polymers 13, no. 10 (May 16, 2021): 1604. http://dx.doi.org/10.3390/polym13101604.

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Poly(vinyl alcohol) nanofibrous mats containing ad hoc synthesized gold nanostructures were prepared via a single-step electrospinning procedure and investigated as a novel composite platform with several potential applications. Specifically, the effect of differently shaped and sized gold nanostructures on the resulting mat physical-chemical properties was investigated. In detail, nearly spherical nanoparticles and nanorods were first synthesized through a chemical reduction of gold precursors in water by using (hexadecyl)trimethylammonium bromide as the stabilizing agent. These nanostructures were then dispersed in poly(vinyl alcohol) aqueous solutions to prepare nanofibrous mats, which were then stabilized via a humble thermal treatment able to enhance their thermal stability and water resistance. Remarkably, the nanostructure type was proven to influence the mesh morphology, with the small spherical nanoparticles and the large nanorods leading to thinner well defined or bigger defect-rich nanofibers, respectively. Finally, the good mechanical properties shown by the prepared composite mats suggest their ease of handleability thereby opening new perspective applications.

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Gonçalves, R. R., A. Lukowiak, D. Ristic, B. Boulard, A. Chiappini, A. Chiasera, D. Dorosz, M. Marciniak, G. C. Righini, and M. Ferrari. "Red photonic glasses and confined structures." Bulletin of the Polish Academy of Sciences Technical Sciences 62, no. 4 (December 1, 2014): 647–53. http://dx.doi.org/10.2478/bpasts-2014-0071.

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Abstract We present some recent results obtained by our team in rare earth doped photonic glasses and confined structures, in order to give some highlights regarding the state of art in glass photonics. To evidence the unique properties of transparent glass ceramics we compare spectroscopic and structural properties between the parent glass and the glass ceramics. Starting from planar waveguides we move to spherical microresonators, a very interesting class of photonic confined structures. We also conclude the short review with some remarks about the perspective for glass photonics.

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Oschman, James L. "Perspective: Assume a spherical cow: The role of free or mobile electrons in bodywork, energetic and movement therapies." Journal of Bodywork and Movement Therapies 12, no. 1 (January 2008): 40–57. http://dx.doi.org/10.1016/j.jbmt.2007.08.002.

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Smorchkova, Yu V., E. A. Avdonina, and A. V. Dedov. "INVESTIGATION OF THERMOHYDRAULIC AND NEUTRON -PHYSICAL CHARACTERISTICS OF PERSPECTIVE FUEL ASSEMBLY FOR LOW-POWER REACTOR FACILITY." Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS 20, no. 7-8 (September 8, 2018): 23–34. http://dx.doi.org/10.30724/1998-9903-2018-20-7-8-23-34.

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The paper presents the results of a numerical study of hydrodynamics and a temperature field in the model of the fuel assembly for the KLT-40S reactor installation in the transition to a fuel consisting of spherical microfuels. The optimal design of a model of a f uel assembly with microfuels for a reactor installation KLT-40S is proposed, from the position of hydrodynamics and heat transfer. The fuel assembly by external dimensions completely corresponds to the traditional assembly with rod fuel elements. The optim al parameters of the perforation of the covers that retain the pebble bed of microfuels are determined. The results of the evaluation of neutron-physical characteristics are presented. The working capacity of the KLT-40S reactor installation is shown when using fuel from microfuel elements.

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Stein-Montalvo, Lucia, Douglas P. Holmes, and Gwennou Coupier. "Delayed buckling of spherical shells due to viscoelastic knockdown of the critical load." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, no. 2253 (September 2021): 20210253. http://dx.doi.org/10.1098/rspa.2021.0253.

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We performed dynamic pressure buckling experiments on defect-seeded spherical shells made of a common silicone elastomer. Unlike in quasi-static experiments, shells buckled at ostensibly subcritical pressures, i.e. below the experimentally determined critical load at which buckling occurs elastically, often following a significant delay period from the time of load application. While emphasizing the close connections to elastic shell buckling, we rely on viscoelasticity to explain our observations. In particular, we demonstrate that the lower critical load may be determined from the material properties, which is rationalized by a simple analogy to elastic spherical shell buckling. We then introduce a model centred on empirical quantities to show that viscoelastic creep deformation lowers the critical load in the same predictable, quantifiable way that a growing defect would in an elastic shell. This allows us to capture how both the deflection at instability and the time delay depend on the applied pressure, material properties and defect geometry. These quantities are straightforward to measure in experiments. Thus, our work not only provides intuition for viscoelastic behaviour from an elastic shell buckling perspective but also offers an accessible pathway to introduce tunable, time-controlled actuation to existing mechanical actuators, e.g. pneumatic grippers.

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Journal articles on the topic 'Spherical perspective'

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