Academic literature on the topic 'MESH POINTS'
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Journal articles on the topic "MESH POINTS"
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Gao, Ying, Rui Zhao Wang, and Jue Yuan. "Interest Points Guided Mesh Simplification." Applied Mechanics and Materials 263-266 (December 2012): 2320–23. http://dx.doi.org/10.4028/www.scientific.net/amm.263-266.2320.
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Based on interest point detection, a feature preserving mesh simplification algorithm is proposed. The Harris operator values of all vertices in the mesh were computed firstly. On the base of Garland’s simplification algorithm, we combine the Harris operator value with quadric error metric and change the order of edge collapsing in the simplification. The experimental results show that the proposed algorithm is effective and feature preserving.
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JIAO, Xue, Huixin ZHANG, and Tieru WU. "Mesh segmentation guided by seed points." Journal of Advanced Mechanical Design, Systems, and Manufacturing 9, no. 4 (2015): JAMDSM0051. http://dx.doi.org/10.1299/jamdsm.2015jamdsm0051.
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Sun, Yan, Xuelin Deng, Liangli He, and Haiyan Yao. "Regularization Method for Discrete Mesh Points." Journal of Computer-Aided Design & Computer Graphics 34, no. 05 (May 1, 2022): 804–10. http://dx.doi.org/10.3724/sp.j.1089.2022.19003.
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Medimegh, Nassima, Samir Belaid, Mohamed Atri, and Naoufel Werghi. "3D mesh watermarking using salient points." Multimedia Tools and Applications 77, no. 24 (June 18, 2018): 32287–309. http://dx.doi.org/10.1007/s11042-018-6252-6.
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Lei, Humin, Tao Liu, Deng Li, Jikun Ye, and Lei Shao. "Adaptive Mesh Iteration Method for Trajectory Optimization Based on Hermite-Pseudospectral Direct Transcription." Mathematical Problems in Engineering 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/2184658.
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An adaptive mesh iteration method based on Hermite-Pseudospectral is described for trajectory optimization. The method uses the Legendre-Gauss-Lobatto points as interpolation points; then the state equations are approximated by Hermite interpolating polynomials. The method allows for changes in both number of mesh points and the number of mesh intervals and produces significantly smaller mesh sizes with a higher accuracy tolerance solution. The derived relative error estimate is then used to trade the number of mesh points with the number of mesh intervals. The adaptive mesh iteration method is applied successfully to the examples of trajectory optimization of Maneuverable Reentry Research Vehicle, and the simulation experiment results show that the adaptive mesh iteration method has many advantages.
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Liu, Yong-Jin, and Matthew Ming-Fai Yuen. "Optimized triangle mesh reconstruction from unstructured points." Visual Computer 19, no. 1 (March 1, 2003): 23–37. http://dx.doi.org/10.1007/s00371-002-0162-2.
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Ejlali, Nastaran, and Seyed Mohammad Hosseini. "Adaptive control parameterization method by density functions for optimal control problems." IMA Journal of Mathematical Control and Information 37, no. 2 (April 1, 2019): 497–512. http://dx.doi.org/10.1093/imamci/dnz010.
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Abstract This paper proposes an efficient adaptive control parameterization method for solving optimal control problems. In this method, mesh density functions are used to generate mesh points. In the first step, the problem is solved by control parameterization on uniform mesh points. Then at each step, the approximate control obtained from the previous step is applied to construct a mesh density function, and consequently a new adapted set of mesh points. Several numerical examples are included to demonstrate that the adaptive control parameterization method is more accurate than a uniform control parameterization one.
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Oh, Sahuck. "A New Mesh Moving Technique for a Fluid–Structure Interaction Problem Using Mesh Deformation Energy Minimization." International Journal of Computational Methods 18, no. 01 (July 19, 2019): 1950039. http://dx.doi.org/10.1142/s0219876219500397.
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When mesh boundaries move in a simulation because of the motion of a target object such as translation, rotation, and oscillation, the mesh should be regenerated to the points it will obey the locations of its new boundaries. Because recreating new mesh from the beginning is a time-consuming task, new mesh is usually created by deforming an initial mesh, which is called the mesh moving method (or mesh deformation method). In this paper, we present a new mesh moving method that produces a higher quality deformed mesh than the current mesh moving methods. In the proposed method, the deformation of mesh is evaluated by two energy quantities that are related to (i) the distortion of mesh that is invariant to translation, rotation, and size changes of the elements of the mesh and (ii) the deformation of mesh calculated using elements’ size based on stiffened-linear elasticity equations. The total deformation energy of mesh is defined as a weighted sum of these two quantities. Because there is no need to pre-fix the locations of the outer boundary points for most mesh moving problems, we use new constraints, allowing the outer boundary points to move along tangential directions in the proposed method. The deformed mesh is computed by calculating the positions of the mesh points where the total deformation energy of the mesh is minimized. For test purposes, the proposed method is applied to 2D triangular meshes and a 3D tetrahedral mesh, where the meshes are deformed by the motions of the target objects such as translation, rotation, and deformation. When the quality of the deformed meshes computed with the proposed method are compared with the ones computed with current mesh moving methods, the meshes from the proposed method are shown to be better than the other meshes.
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EZAWA, Yoshitaka. "Automatic mesh generation by automatic generating internal points." Proceedings of The Computational Mechanics Conference 2003.16 (2003): 755–56. http://dx.doi.org/10.1299/jsmecmd.2003.16.755.
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Remski, Joan. "Mesh Spacing Estimates and Efficiency Considerations for Moving Mesh Systems." Numerical Mathematics: Theory, Methods and Applications 9, no. 3 (July 20, 2016): 432–50. http://dx.doi.org/10.4208/nmtma.2016.m1508.
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AbstractAdaptive numerical methods for solving partial differential equations (PDEs) that control the movement of grid points are called moving mesh methods. In this paper, these methods are examined in the case where a separate PDE, that depends on a monitor function, controls the behavior of the mesh. This results in a system of PDEs: one controlling the mesh and another solving the physical problem that is of interest. For a class of monitor functions resembling the arc length monitor, a trade off between computational efficiency in solving the moving mesh system and the accuracy level of the solution to the physical PDE is demonstrated. This accuracy is measured in the density of mesh points in the desired portion of the domain where the function has steep gradient. The balance of computational efficiency versus accuracy is illustrated numerically with both the arc length monitor and a monitor that minimizes certain interpolation errors. Physical solutions with steep gradients in small portions of their domain are considered for both the analysis and the computations.
Dissertations / Theses on the topic "MESH POINTS"
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Itier, Vincent. "Nouvelles méthodes de synchronisation de nuages de points 3D pour l'insertion de données cachées." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS017/document.
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Cette thèse aborde les problèmes liés à la protection de maillages d'objets 3D. Ces objets peuvent, par exemple, être créés à l'aide d'outil de CAD développés par la société STRATEGIES. Dans un cadre industriel, les créateurs de maillages 3D ont besoin de disposer d'outils leur permettant de vérifier l'intégrité des maillages, ou de vérifier des autorisations pour l'impression 3D par exemple. Dans ce contexte nous étudions l'insertion de données cachées dans des maillages 3D. Cette approche permet d'insérer de façon imperceptible et sécurisée de l'information dans un maillage. Il peut s'agir d'un identifiant, de méta-informations ou d'un contenu tiers, par exemple, pour transmettre de façon secrète une texture. L'insertion de données cachées permet de répondre à ces problèmes en jouant sur le compromis entre la capacité, l'imperceptibilité et la robustesse. Généralement, les méthodes d'insertion de données cachées se composent de deux phases, la synchronisation et l'insertion. La synchronisation consiste à trouver et ordonner les éléments disponibles pour l'insertion. L'un des principaux challenges est de proposer une méthode de synchronisation 3D efficace qui définit un ordre sur les composants des maillages. Dans nos travaux, nous proposons d'utiliser les sommets du maillage, plus précisément leur représentation géométrique dans l'espace comme composants de base pour la synchronisation et l'insertion. Nous présentons donc trois nouvelles méthodes de synchronisation de la géométrie des maillages basées sur la construction d'un chemin hamiltonien dans un nuage de sommets. Deux de ces méthodes permettent de manière conjointe de synchroniser les sommets et de cacher un message. Cela est possible grâce à deux nouvelles méthodes d'insertion haute capacité (de $3$ à $24$ bits par sommet) qui s'appuient sur la quantification des coordonnées. Dans ces travaux nous mettons également en évidence les contraintes propres à ce type de synchronisation. Nous discutons des différentes approches proposées dans plusieurs études expérimentales. Nos travaux sont évalués sur différents critères dont la capacité et l'imperceptibilité de la méthode d'insertion. Nous portons également notre attention aux aspects sécurité des méthodesThis thesis addresses issues relating to the protection of 3D object meshes. For instance, these objects can be created using CAD tool developed by the company STRATEGIES. In an industrial context, 3D meshes creators need to have tools in order to verify meshes integrity, or check permission for 3D printing for example.In this context we study data hiding on 3D meshes. This approach allows us to insert information in a secure and imperceptible way in a mesh. This may be an identifier, a meta-information or a third-party content, for instance, in order to transmit secretly a texture. Data hiding can address these problems by adjusting the trade-off between capacity, imperceptibility and robustness. Generally, data hiding methods consist of two stages, the synchronization and the embedding. The synchronization stage consists of finding and ordering available components for insertion. One of the main challenges is to propose an effective synchronization method that defines an order on mesh components. In our work, we propose to use mesh vertices, specifically their geometric representation in space, as basic components for synchronization and embedding. We present three new synchronisation methods based on the construction of a Hamiltonian path in a vertex cloud. Two of these methods jointly perform the synchronization stage and the embedding stage. This is possible thanks to two new high-capacity embedding methods (from 3 to 24 bits per vertex) that rely on coordinates quantization. In this work we also highlight the constraints of this kind of synchronization. We analyze the different approaches proposed with several experimental studies. Our work is assessed on various criteria including the capacity and imperceptibility of the embedding method. We also pay attention to security aspects of the proposed methods
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Parisot, Pascaline. "Suivi d’objets dans des séquences d’images de scènes déformables : de l’importance des points d’intérêt et du maillage 2D." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT012H/document.
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Nous abordons le suivi d’objets dans des séquences d’images de scènes déformables selon deux axes de recherche. Il s’agit de déterminer les transformations d’un objet, d’une image à l’autre, lorsque celui-ci s’est éventuellement déformé ou déplacé et lorsque le point de vue de la caméra a éventuellement été modifié (déplacement, zoom...). Pour cela, nous nous sommes inspirés de l’algorithme de Jurie et Dhome qui permet de suivre un objet plan indéformable. D’une part, nous en améliorons les performances. D’autre part, nous le généralisons au cas d’objets déformables. Le premier axe de recherche consiste à améliorer les performances de l’algorithme de Jurie et Dhome en termes de précision et robustesse. Le suivi s’appuie sur un ensemble de points d’intérêt, dont dépendent fortement les performances. Ces points d’intérêt sont issus d’une sélection des points obtenus par des détecteurs reconnus, à savoir SIFT, KLT, SUSAN, HARRIS et MORAVEC. Nous avons étudié et mis en oeuvre, sur différentes classes d’images, des heuristiques de sélection fondées sur des approches statistique et algébrique. Nous montrons : – qu’il n’existe pas de détecteur universel, – que l’approche statistique est à privilégier dans tous les cas. Le second axe de recherche est une proposition d’un nouvel algorithme de suivi s’appuyant sur le maillage 2D des images de la séquence. Cet algorithme généralise celui de Jurie et Dhome aux scènes déformables. Il repose sur : – des transformations élémentaires (nodales) du maillage, directes et inverses, que nous avons caractérisées tant d’un point de vue géométrique qu’analytique, – l’utilisation des coordonnées barycentriques généralisées pour approcher la composition de deux transformations d’un maillage. Cet algorithme donne des résultats similaires à celui d’appariement hexagonal de Nakaya et Harashima tout en étant plus rapideWe deal with object tracking in videos of non-rigid scenes with two main purposes. We aim at determining the transformations of an object, from one frame to the next, when it may be distorted or moved and when the camera focus may change (movement, zoom...). To do this, we were inspired by the Jurie and Dhome algorithm, which enables the tracking of plane rigid objects. On the one hand, we improve its performance. On the other hand, we generalize it to non-rigid objects. The first goal consists in improving the performance of the Jurie and Dhome algorithm, in terms of accuracy and robustness. The tracking is based on a set of interest points, which has a great effect on the algorithm’s performance. These interest points come from a selection among the points extracted with some common detectors: SIFT, KLT, SUSAN, HARRIS, and MORAVEC.With various pictures classes, we have studied and implemented some selection heuristics based on statistical or algebraic approaches. We show that : • there is no universal detector, • the statistical approach is the best in all cases. The second goal is a proposal of a new tracking algorithm based on a 2D mesh of the video frames. This algorithm generalizes the Jurie and Dhome one for non-rigid scenes. It is based on : • elementary (nodal), direct or inverse, mesh transformations that we geometrically and analytically characterize, • generalized barycentric coordinates to approximate the composition of two mesh transformations. This algorithm gives similar results to the hexagonal matching algorithm of Nakaya and Harashima while being faster
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Loménie, Nicolas. "Interprétation de nuages de points : application à la modélisaion d'environnements 3D en robotique mobile." Phd thesis, Université René Descartes - Paris V, 2001. http://tel.archives-ouvertes.fr/tel-00136113.
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Cette thèse traite de l'analyse de nuages de points 3D désorganisé et s'appuie sur deux outils : un algorithme de partitionnement efficace inspiré des C-moyennes floues d'une part, et des outils de filtrage morphologique de représentation à base de triangulation de Delaunay d'autre part. Le cadre applicatif essentiel est la navigation autonome en robotique mobile en environnement inconnu, c'est-à-dire dans modèle. Mais la méthodologie générique développée a été appliquée à d'autres types d'environnements, notamment plus structurés.
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Akdag, Osman. "Incompressible Flow Simulations Using Least Squares Spectral Element Method On Adaptively Refined Triangular Grids." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614944/index.pdf.
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The main purpose of this study is to develop a flow solver that employs triangular grids to solve two-dimensional, viscous, laminar, steady, incompressible flows. The flow solver is based on Least Squares Spectral Element Method (LSSEM). It has p-type adaptive mesh refinement/coarsening capability and supports p-type nonconforming element interfaces. To validate the developed flow solver several benchmark problems are studied and successful results are obtained. The performances of two different triangular nodal distributions, namely Lobatto distribution and Fekete distribution, are compared in terms of accuracy and implementation complexity. Accuracies provided by triangular and quadrilateral grids of equal computational size are compared. Adaptive mesh refinement studies are conducted using three different error indicators, including a novel one based on elemental mass loss. Effect of modifying the least-squares functional by multiplying the continuity equation by a weight factor is investigated in regards to mass conservation.
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Ben, salah Imeen. "Extraction d'un graphe de navigabilité à partir d'un nuage de points 3D enrichis." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR070/document.
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Les caméras sont devenues de plus en plus communes dans les véhicules, les smartphones et les systèmes d'aide à la conduite ADAS (Advanced Driver Assistance Systèmes). Les domaines d'application de ces caméras dans le monde des systèmes intelligents de transport deviennent de plus en plus variés : la détection des piétons, les avertissements de franchissement de ligne, la navigation... La navigation basée sur la vision a atteint une certaine maturité durant ces dernières années grâce à l'utilisation de technologies avancées. Les systèmes de navigation basée sur la vision ont le considérable avantage de pouvoir utiliser directement les informations visuelles présentes dans l'environnement, sans devoir adapter le moindre élément de l'infrastructure. De plus, contrairement aux systèmes utilisant le GPS, ils peuvent être utilisés à l'extérieur ainsi qu'à l'intérieur des locaux et des bâtiments sans aucune perte de précision. C'est pour ces raisons que les systèmes basés sur la vision sont une bonne option car ils fournissent des informations très riches et précises sur l'environnement, qui peuvent être utilisées pour la navigation. Un axe important de recherche porte actuellement sur la cartographie qui représente une étape indispensable pour la navigation. Cette étape engendre une problématique de la gestion de la mémoire assez conséquente requise par ces systèmes en raison de la quantité d'informations importante collectées par chaque capteur. En effet, l'espace mémoire nécessaire pour accueillir la carte d'une petite ville se mesure en dizaines de GO voire des milliers lorsque l'on souhaite couvrir des espaces de grandes dimensions. Cela rend impossible son intégration dans un système mobile tel que les smartphones, les véhicules, les vélos ou les robots. Le défi serait donc de développer de nouveaux algorithmes permettant de diminuer au maximum la taille de la mémoire nécessaire pour faire fonctionner ce système de localisation par vision. C'est dans ce contexte que se situe notre projet qui consiste à développer un nouveau système capable de résumer une carte 3D qui contient des informations visuelles collectées par plusieurs capteurs. Le résumé sera un ensemble des vues sphériques permettant de garder le même niveau de visibilité dans toutes les directions. Cela permettrait aussi de garantir, à moindre coût, un bon niveau de précision et de rapidité lors de la navigation. La carte résumant l'environnement sera constituée d'un ensemble d'informations géométriques, photométriques et sémantiquesCameras have become increasingly common in vehicles, smart phones, and advanced driver assistance systems. The areas of application of these cameras in the world of intelligent transportation systems are becoming more and more varied : pedestrian detection, line crossing detection, navigation ... Vision-based navigation has reached a certain maturity in recent years through the use of advanced technologies. Vision-based navigation systems have the considerable advantage of being able to directly use the visual information already existing in the environment without having to adapt any element of the infrastructure. In addition, unlike systems using GPS, they can be used outdoors and indoors without any loss of precision. This guarantees the superiority of these systems based on computer vision. A major area of {research currently focuses on mapping, which represents an essential step for navigation. This step generates a problem of memory management quite substantial required by these systems because of the huge amount of information collected by each sensor. Indeed, the memory space required to accommodate the map of a small city is measured in tens of GB or even thousands when one wants to cover large spaces. This makes impossible to integrate this map into a mobile system such as smartphones , cameras embedded in vehicles or robots. The challenge would be to develop new algorithms to minimize the size of the memory needed to operate this navigation system using only computer vision. It's in this context that our project consists in developing a new system able to summarize a3D map resulting from the visual information collected by several sensors. The summary will be a set of spherical views allow to keep the same level of visibility in all directions. It would also guarantee, at a lower cost, a good level of precision and speed during navigation. The summary map of the environment will contain geometric, photometric and semantic information
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Vasiliauskienė, Lina. "Prisitaikančiosios baigtinių elementų strategijos plokštuminiams tamprumo teorijos uždaviniams." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060622_134743-74080.
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The advent of modern computer technologies provided a powerful tool in numerical simulations. One of the most frequently used method for the discretization of the physical domain is Finite element Method (FEM). One of the main problems in a finite element analysis is the adequacy of the finite element mesh. Since the quality of the finite element solution directly depends on the quality of meshes, the additional process to improve the quality of meshes is necessary for reliable finite element approximation. In order to perform quality-assessed numerical simulation, the adaptive finite element strategies have been developed. These strategies integrate the finite element analysis with error estimation and fully automatic mesh modification, user interaction with this process is limited by initial geometry data and possible error tolerance definition. The finite element solution, obtained during adaptive finite element strategy process, approximates quite good different engineering structures. Despite many works in this area the problem of the adequate finite element mesh is not fully solved and additional developments are needed in order to improve adaptive mesh refinement strategy process. The aim and tasks of the work – to obtain methodology for quality assessed discretization to finite elements for complex geometry engineering structures by adaptive finite element strategies. To realize this purpose the following scientific tasks have been dealt: to develop an automatic... [to full text]
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Santoso, Mas Simon. "Simulation d'écoulements fluides à partir de données réelles." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0011.
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Les nuages de points sont des objets mathématiques permettant de décrire de manière discrète des fonctions à plusieurs variables. Ils sont principalement utilisés dans le domaine statistique mais on les retrouve également en géométrie afin de représenter des variétés géométriques complexes. Il est aujourd'hui difficile d'intégrer les objets représentés par ces nuages de points dans des calculs éléments finis car l'intégration de ces nuages de points requiert la reconstruction de la variété ainsi que la génération d'un maillage surfacique qu'il faut intégrer dans un maillage volumique. Ces opérations sont souvent basées sur des processus itératifs et sont extrêmement coûteuses en temps car les nuages de points utilisés sont de très grande taille. La méthodologie développée dans cette thèse permet d'immerger des nuages de points dans un domaine maillé sans passer par les étapes de reconstruction de surface et de génération de maillage. On utilise la technique d'immersion de volume adaptée aux nuages de points. Cette technique est couplée avec une méthode d'adaptation de maillage. Cela nous permettra de générer un maillage anisotropique adapté autour des zones d'intérêt. On utilise ensuite la méthode variationnelle multi-échelle afin de simuler des écoulements fluides. Cette technique est une extension de la méthode éléments finis classique permettant de simuler des écoulements à forte convection et à haut nombre de Reynolds. La dernière partie de ce manuscrit présente quelques cas d'application dans le domaine aérodynamique, hydrodynamique et urbainsPoints clouds are mathematical objects that allows to describe discretely multivariable functions. They are mainly used in the statistical domain but also in geometrical manifolds. It is nowadays a real challenge to immerse the previous manifolds in finite element computation. Indeed, the immersion of those points clouds requires the reconstruction of the surface of the manifold and the generation of a surfacic mesh. As those operations are often based on an iterative process, they are extremely time-consuming as points clouds are usually massive. The method developed in this thesis allows to immerse points clouds in a meshed domain without the surface reconstruction and mesh generations steps. For that purpose, we use the Volume Immersion Method adapted to point clouds. We coupled this method with an adaped mesh generation technique. Then we are able to generate a monolithic anisotropic mesh, adapted around interest zones. We also use the variational multi-scale method to simulate fluid flow. This method is an extension of the classical finite element method and allows to simulate fluid flow. The last part of this thesis introduce some applications cases in the aerodynamic and urbans domains
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El, Sayed Abdul Rahman. "Traitement des objets 3D et images par les méthodes numériques sur graphes." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMLH19/document.
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La détection de peau consiste à détecter les pixels correspondant à une peau humaine dans une image couleur. Les visages constituent une catégorie de stimulus importante par la richesse des informations qu’ils véhiculent car avant de reconnaître n’importe quelle personne il est indispensable de localiser et reconnaître son visage. La plupart des applications liées à la sécurité et à la biométrie reposent sur la détection de régions de peau telles que la détection de visages, le filtrage d'objets 3D pour adultes et la reconnaissance de gestes. En outre, la détection de la saillance des mailles 3D est une phase de prétraitement importante pour de nombreuses applications de vision par ordinateur. La segmentation d'objets 3D basée sur des régions saillantes a été largement utilisée dans de nombreuses applications de vision par ordinateur telles que la correspondance de formes 3D, les alignements d'objets, le lissage de nuages de points 3D, la recherche des images sur le web, l’indexation des images par le contenu, la segmentation de la vidéo et la détection et la reconnaissance de visages. La détection de peau est une tâche très difficile pour différentes raisons liées en général à la variabilité de la forme et la couleur à détecter (teintes différentes d’une personne à une autre, orientation et tailles quelconques, conditions d’éclairage) et surtout pour les images issues du web capturées sous différentes conditions de lumière. Il existe plusieurs approches connues pour la détection de peau : les approches basées sur la géométrie et l’extraction de traits caractéristiques, les approches basées sur le mouvement (la soustraction de l’arrière-plan (SAP), différence entre deux images consécutives, calcul du flot optique) et les approches basées sur la couleur. Dans cette thèse, nous proposons des méthodes d'optimisation numérique pour la détection de régions de couleurs de peaux et de régions saillantes sur des maillages 3D et des nuages de points 3D en utilisant un graphe pondéré. En se basant sur ces méthodes, nous proposons des approches de détection de visage 3D à l'aide de la programmation linéaire et de fouille de données (Data Mining). En outre, nous avons adapté nos méthodes proposées pour résoudre le problème de la simplification des nuages de points 3D et de la correspondance des objets 3D. En plus, nous montrons la robustesse et l’efficacité de nos méthodes proposées à travers de différents résultats expérimentaux réalisés. Enfin, nous montrons la stabilité et la robustesse de nos méthodes par rapport au bruitSkin detection involves detecting pixels corresponding to human skin in a color image. The faces constitute a category of stimulus important by the wealth of information that they convey because before recognizing any person it is essential to locate and recognize his face. Most security and biometrics applications rely on the detection of skin regions such as face detection, 3D adult object filtering, and gesture recognition. In addition, saliency detection of 3D mesh is an important pretreatment phase for many computer vision applications. 3D segmentation based on salient regions has been widely used in many computer vision applications such as 3D shape matching, object alignments, 3D point-point smoothing, searching images on the web, image indexing by content, video segmentation and face detection and recognition. The detection of skin is a very difficult task for various reasons generally related to the variability of the shape and the color to be detected (different hues from one person to another, orientation and different sizes, lighting conditions) and especially for images from the web captured under different light conditions. There are several known approaches to skin detection: approaches based on geometry and feature extraction, motion-based approaches (background subtraction (SAP), difference between two consecutive images, optical flow calculation) and color-based approaches. In this thesis, we propose numerical optimization methods for the detection of skins color and salient regions on 3D meshes and 3D point clouds using a weighted graph. Based on these methods, we provide 3D face detection approaches using Linear Programming and Data Mining. In addition, we adapted our proposed methods to solve the problem of simplifying 3D point clouds and matching 3D objects. In addition, we show the robustness and efficiency of our proposed methods through different experimental results. Finally, we show the stability and robustness of our methods with respect to noise
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Bouchiba, Hassan. "Contributions en traitements basés points pour le rendu et la simulation en mécanique des fluides." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM076/document.
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Le nuage de points 3D est la donnée obtenue par la majorité des méthodes de numérisation surfacique actuelles. Nous nous intéressons ainsi dans cette thèse à l'utilisation de nuages de points comme unique représentation explicite de surface. Cette thèse présente deux contributions en traitements basés points. La première contribution proposée est une nouvelle méthode de rendu de nuages de points bruts et massifs par opérateurs pyramidaux en espace image. Cette nouvelle méthode s'applique aussi bien à des nuages de points d'objets scannés, que de scènes complexes. La succession d'opérateurs en espace image permet alors de reconstruire en temps réel une surface et d'en estimer des normales, ce qui permet par la suite d'en obtenir un rendu par ombrage. De plus, l'utilisation d'opérateurs pyramidaux en espace image permet d'atteindre des fréquences d'affichage plus élevées d'un ordre de grandeur que l'état de l'art .La deuxième contribution présentée est une nouvelle méthode de simulation numérique en mécanique des fluides en volumes immergés par reconstruction implicite étendue. La méthode proposée se base sur une nouvelle définition de surface implicite par moindres carrés glissants étendue à partir d'un nuage de points. Cette surface est alors utilisée pour définir les conditions aux limites d'un solveur Navier-Stokes par éléments finis en volumes immergés, qui est utilisé pour simuler un écoulement fluide autour de l'objet représenté par le nuage de points. Le solveur est interfacé à un mailleur adaptatif anisotrope qui permet de capturer simultanément la géométrie du nuage de points et l'écoulement à chaque pas de temps de la simulationMost surface 3D scanning techniques produce 3D point clouds. This thesis tackles the problem of using points as only explicit surface representation. It presents two contributions in point-based processing. The first contribution is a new raw and massive point cloud screen-space rendering algorithm. This new method can be applied to a wide variety of data from small objects to complex scenes. A sequence of screen-space pyramidal operators is used to reconstruct in real-time a surface and estimate its normals, which are later used to perform deferred shading. In addition, the use of pyramidal operators allows to achieve framerate one order of magnitude higher than state of the art methods. The second proposed contribution is a new immersed boundary computational fluid dynamics method by extended implicit surface reconstruction. The proposed method is based on a new implicit surface definition from a point cloud by extended moving least squares. This surface is then used to define the boundary conditions of a finite-elements immersed boundary transient Navier-Stokes solver, which is used to compute flows around the object sampled by the point cloud. The solver is interfaced with an anisotropic and adaptive meshing algorithm which refines the computational grid around both the geometry defined by point cloud and the flow at each timestep of the simulation
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Fang, Hao. "Modélisation géométrique à différent niveau de détails d'objets fabriqués par l'homme." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4002/document.
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La modélisation géométrique d'objets fabriqués par l'homme à partir de données 3D est l'un des plus grands défis de la vision par ordinateur et de l'infographie. L'objectif à long terme est de générer des modèles de type CAO de la manière la plus automatique possible. Pour atteindre cet objectif, des problèmes difficiles doivent être résolus, notamment (i) le passage à l'échelle du processus de modélisation sur des données d'entrée massives, (ii) la robustesse de la méthodologie contre des mesures d'entrées erronés, et (iii) la qualité géométrique des modèles de sortie. Les méthodes existantes fonctionnent efficacement pour reconstruire la surface des objets de forme libre. Cependant, dans le cas d'objets fabriqués par l'homme, il est difficile d'obtenir des résultats dont la qualité approche celle des représentations hautement structurées, comme les modèles CAO. Dans cette thèse, nous présentons une série de contributions dans ce domaine. Tout d'abord, nous proposons une méthode de classification basée sur l'apprentissage en profondeur pour distinguer des objets dans des environnements complexes à partir de nuages de points 3D. Deuxièmement, nous proposons un algorithme pour détecter des primitives planaires dans des données 3D à différents niveaux d'abstraction. Enfin, nous proposons un mécanisme pour assembler des primitives planaires en maillages polygonaux compacts. Ces contributions sont complémentaires et peuvent être utilisées de manière séquentielle pour reconstruire des modèles de ville à différents niveaux de détail à partir de données 3D aéroportées. Nous illustrons la robustesse, le passage à l'échelle et l'efficacité de nos méthodes sur des données laser et multi-vues stéréo sur des scènes composées d'objets fabriqués par l'hommeGeometric modeling of man-made objects from 3D data is one of the biggest challenges in Computer Vision and Computer Graphics. The long term goal is to generate a CAD-style model in an as-automatic-as-possible way. To achieve this goal, difficult issues have to be addressed including (i) the scalability of the modeling process with respect to massive input data, (ii) the robustness of the methodology to various defect-laden input measurements, and (iii) the geometric quality of output models. Existing methods work well to recover the surface of free-form objects. However, in case of manmade objects, it is difficult to produce results that approach the quality of high-structured representations as CAD models.In this thesis, we present a series of contributions to the field. First, we propose a classification method based on deep learning to distinguish objects from raw 3D point cloud. Second, we propose an algorithm to detect planar primitives in 3D data at different level of abstraction. Finally, we propose a mechanism to assemble planar primitives into compact polygonal meshes. These contributions are complementary and can be used sequentially to reconstruct city models at various level-of-details from airborne 3D data. We illustrate the robustness, scalability and efficiency of our methods on both laser and multi-view stereo data composed of man-made objects
Books on the topic "MESH POINTS"
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Michel, Willem, ed. Critical point theory and Hamiltonian systems. New York: Springer-Verlag, 1989.
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Lindauer, Owen. The archaeology of Schoolhouse Point Mesa, Roosevelt Platform Mound Study: Report on the Schoolhouse Point Mesa Sites, Schoolhouse Management Group, Pinto Creek Complex. Tempe, AZ: Arizona State University Office of Cultural Resource Management, 1997.
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Mes points sur les i: Propos sur la présidentielle et la crise. Paris: Odile Jacob, 2012.
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Rivett, Mary L. Full mesh audio conferencing using the point-to-multipoint on-board switching capability of ACTS. [Washington, DC]: National Aeronautics and Space Administration, 1996.
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Boutaudou, Sylvie. Marre de mes kilos en trop. Paris: La Martinière jeunesse, 2008.
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United States. National Aeronautics and Space Administration., ed. Full Mesh Audio Conferencing Using The Point-To-Multipoint On-Board Switching Capability Of ACTS Final Report... NASA-CR-198498... Mar. 14, 1997. [S.l: s.n., 1998.
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Bauch, Nancy J. Limnology of Blue Mesa, Morrow Point, and Crystal Reservoirs, Curecanti National Recreation area, during 1999, and a 25-year retrospective of nutrient conditions in Blue Mesa Reservoir, Colorado. Denver, Colo: U.S. Dept. of the Interior, U.S. Geological Survey, 2003.
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Benkato, Adam, Leila Tayeb, and Amina Zarrugh, eds. Lamma. Earth, Milky Way: punctum books, 2023. http://dx.doi.org/10.53288/0504.1.00.
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Lamma aims to provide a forum for critically understanding the complex ideas, values, social configurations, histories, and material realities in Libya. Recognizing, and insisting on, the urgent need for such a forum, we give attention to as wide a range of disciplines, sources, and approaches as possible, foregrounding especially those which have previously received less scholarly attention. This includes, but is not limited to: anthropology, art, gender, history, linguistics, literature, music, performance studies, politics, religion, and urban studies, in addition to their intersections, their subfields, the places in between, and critical, theoretical, and postcolonial approaches thereto. Lamma is a space where these fields interact and draw from one another, and where scholars and students from inside and outside of Libya gather to redefine and reshape “Libyan Studies”. We believe that access to research is not the privilege of a few but the right of all and that knowledge production should be inclusive. For these reasons the journal takes its name from the Arabic word lamma “a gathering.” The contributions in this second issue help to open up space for interrelated discussions on a variety of topics, almost all largely neglected in the contemporary scholarly study of Libya. The focal point of this issue is the reflective contributions by members of a roundtable discussion “Methods and Sources for a New Generation of Libyan Studies” which took place at the 2020 MESA conference. We also mark the publication of a watershed book on genocide in colonial Libya with a trio of responses. As ever, we believe in the generative power in dialoguing and mixing works of art, literature, and scholarship as we seek to shape and re-shape new discussions on, about, from, and in Libya.
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Ruschmann, Paul. Prescription and Non-prescription Drugs (Point/Counterpoint). Chelsea House Publications, 2007.
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MES PREMIERS POINT-A-POINT. Héritage, 2004.
Find full textBook chapters on the topic "MESH POINTS"
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Hui, Suk Yu, Kai Hau Yeung, and Kin Yeung Wong. "Optimal Placement of Mesh Points in Wireless Mesh Networks." In NETWORKING 2008 Ad Hoc and Sensor Networks, Wireless Networks, Next Generation Internet, 848–55. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-79549-0_74.
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Zhao, Dangjun, Zhiwei Zhang, and Mingzhen Gui. "Birkhoff Pseudospectral Method and Convex Programming for Trajectory Optimization." In Autonomous Trajectory Planning and Guidance Control for Launch Vehicles, 99–127. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-0613-0_4.
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AbstractTrajectory optimization, an optimal control problem (OCP) in essence, is an important issue in many engineering applications including space missions, such as orbit insertion of launchers, orbit rescue, formation flying, etc. There exist two kinds of solving methods for OCP, i.e., indirect and direct methods. For some simple OCPs, using the indirect methods can result in analytic solutions, which are not easy to be obtained for complicated systems. Direct methods transcribe an OCPs into a finite-dimensional nonlinear programming (NLP) problem via discretizing the states and the controls at a set of mesh points, which should be carefully designed via compromising the computational burden and the solution accuracy. In general, the larger number of mesh points, the more accurate solution as well as the larger computational cost including CPU time and memory [1]. There are many numerical methods have been developed for the transcription of OCPs, and the most common method is by using Pseudospectral (PS) collocation scheme [2], which is an optimal choice of mesh points in the reason of well-established rules of approximation theory [3]. Actually, there have several mature optimal control toolkits based PS methods, such as DIDO [4], GPOPS [5]. The resulting NLP problem can be solved by the well-known algorithm packages, such as IPOPT [6] or SNOPT [7]. However, these algorithms cannot obtain a solution in polynomial-time, and the resulting solution is locally optimal. Moreover, a good initial guess solution should be provided for complicated problems.
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Cañavate, F. J. F., F. Cavas, J. S. Velázquez, J. M. Bolarín, and J. L. Alió. "Analysis of the Accuracy of Reconstruction of a Human Cornea by Two Geometric Modelling Techniques: A Comparative Study." In Lecture Notes in Mechanical Engineering, 255–60. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_41.
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AbstractThis study compares two techniques of reconstruction and representation of the anterior and posterior surfaces of the human cornea, both for healthy and for keratoconus eyes, in a CAD software environment using raw tomographic data, by two different methods: a mesh model (obtained from a grid of points) and a NURBS surface model. After reconstruction, a morpho-geometric analysis was made, and several parameters were defined and measured in a set of 100 healthy eyes and 61 keratoconus eyes, detecting the statistical analysis significant differences between methods for both groups. Mesh method proved to be more accurate, but less eyes could be modelled. Volumetric and surface measurement values showed a total equivalence between both methods, so these would be the ones to use when modelling eyes for keratoconus detection and characterization purposes.
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Mouhamed, Mourad R., Mona M. Soliman, Ashraf A. Darwish, and Aboul Ella Hassanien. "Interest Points Detection of 3D Mesh Model Using K Means and Shape Curvature." In Advances in Intelligent Systems and Computing, 415–24. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99010-1_38.
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Long, Chengjiang, Jianhui Zhao, Ravindra S. Goonetilleke, Shuping Xiong, Yihua Ding, Zhiyong Yuan, and Yuanyuan Zhang. "A New Region Growing Algorithm for Triangular Mesh Recovery from Scattered 3D Points." In Transactions on Edutainment VI, 237–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-22639-7_23.
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Yachia, Daniel. "Learning from Our Mistakes: Applying Vascular Stent Technologies to the Urinary Tract." In Urinary Stents, 351–58. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04484-7_28.
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AbstractThe aim of this chapter is to clarify certain points which are confusing many if not most of our urologist colleagues on the subject of “stents and stenting the urinary tract”. Another point of confusion in urology is the term of “chronic obstruction” describing an obstruction necessitating long-term stenting. Which stent to use? For how long? Before using a permanent stent along the urinary tract we should think hard about what may happen to a ureter or urethra implanted with a permanent metallic mesh stent. This is especially important when something goes wrong like when the stent lumen becomes obliterated by hyperplastic or malignant tissues, the stent wires fracture, or tissue coverage over the stent wires is incomplete and the resulting stone formation on the wires, ureteral or urethral perforations etc. By adopting the vascular stent technologies in urinary tract design stents, we were hoping that taking a single stent shape, changing its length and caliber they could be used all along the urinary tract. Then asking ourselves, why the results were less than what we were expecting. Here I would like to quote a sentence attributed to Albert Einstein: “Insanity is doing the same thing over and over again and expecting different results”.
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Dehne, Frank, Jörg-R. Sack, and Ivan Stojmenović. "A note on determining the 3-dimensional convex hull of a set of points on a mesh of processors." In SWAT 88, 154–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/3-540-19487-8_18.
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Tanigawa, Shin-ichi, and Naoki Katoh. "Polygonal Curve Approximation Using Grid Points with Application to a Triangular Mesh Generation with Small Number of Different Edge Lengths." In Algorithmic Aspects in Information and Management, 161–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/11775096_16.
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Poloni, Katia Maria, Carlos Henrique Villa Pinto, Breno da Silveira Souza, and Ricardo José Ferrari. "Construction and Application of a Probabilistic Atlas of 3D Landmark Points for Initialization of Hippocampus Mesh Models in Brain MR Images." In Computational Science and Its Applications – ICCSA 2018, 310–22. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-95162-1_21.
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Liu, Ziqiao, Dongyang Wang, Xiaoying Sun, and Yingying Gan. "Research on Parameter Sensitivity for Deeply Embedment SSI Analysis Based on Sub-structuring Method." In Springer Proceedings in Physics, 445–59. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_39.
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AbstractThis paper carried out a seismic analysis of a nuclear island structure under the site of a soft soil foundation, based on the spatial sub-structuring analysis method. In order to fully consider the influence of embedment effect in the analysis, the embedded part is modeled independently in the model. Then, the sensitivity effects from the number of interaction nodes and the radius of the cylindrical central area on the calculation time and results is studied. The research show that: (1) Selecting the nodes only at the boundary of the embedded part as the interaction points can significantly reduce the calculation time on the premise of ensuring the accuracy of the results. (2) The value of cylindrical radius in finite element model does not affect the calculation time and accuracy significantly, but has a certain effect on the spectrum value. It is suggested to determine the radius using the average value of the elements which are a large proportion in the model for an non-uniform mesh. In this paper, the suggested values for two parameters are provided based on the sensitivity analysis. The conclusions provide technical reference for the seismic analysis of the deeply embedded nuclear buildings.
Conference papers on the topic "MESH POINTS"
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Yue-Ping Feng, Hui-Xiang Zhong, and Yun-Jie Pang. "Non-mesh rendering based on points." In Proceedings of 2005 International Conference on Machine Learning and Cybernetics. IEEE, 2005. http://dx.doi.org/10.1109/icmlc.2005.1527906.
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Sheung, Hoi, and Charlie C. L. Wang. "Robust mesh reconstruction from unoriented noisy points." In 2009 SIAM/ACM Joint Conference on Geometric and Physical Modeling. New York, New York, USA: ACM Press, 2009. http://dx.doi.org/10.1145/1629255.1629258.
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Salvador, Jordi, Xavier Suau, and Josep R. Casas. "From silhouettes to 3D points to mesh." In the 1st international workshop. New York, New York, USA: ACM Press, 2010. http://dx.doi.org/10.1145/1877791.1877797.
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Gong, Faming, and Cui Kang. "3D Mesh Skeleton Extraction Based on Feature Points." In 2009 International Conference on Computer Engineering and Technology (ICCET). IEEE, 2009. http://dx.doi.org/10.1109/iccet.2009.71.
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Xue, Mowen, Xudong Li, Ying Liang, Hongzhi Jiang, and Huijie Zhao. "Image stitching by points grouping and mesh optimization." In Sixth Symposium on Novel Photoelectronic Detection Technology and Application, edited by Huilin Jiang and Junhao Chu. SPIE, 2020. http://dx.doi.org/10.1117/12.2565355.
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Farag, S., W. Abdelrahman, D. Creighton, and S. Nahavandi. "Extracting 3D Mesh Skeletons Using Antipodal Points Locations." In 2013 UKSim 15th International Conference on Computer Modelling and Simulation (UKSim 2013). IEEE, 2013. http://dx.doi.org/10.1109/uksim.2013.78.
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Oviedo, Byron, Luis Moreira, Amilkar Puris, Pavel Novoa, and Serafin Moral. "Learning Bayesian network by a mesh of points." In 2016 IEEE Congress on Evolutionary Computation (CEC). IEEE, 2016. http://dx.doi.org/10.1109/cec.2016.7744295.
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Deo, Dhanannjay, and Dibakar Sen. "Mesh Processing for Computerized Anthropometry." In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-85528.
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Understanding of the shape and size of different features of human body from the scanned data is necessary for automated design and evaluation of product ergonomics. In this paper, a computational framework is presented for automatic detection and recognition of several facial feature-regions from scanned head and shoulder polyhedral models. A noise tolerant methodology is proposed using discrete curvature computations and morphological tools for isolation of the primary feature regions of face namely eye, nose and mouth. Spatial disposition of the critical points of these isolated feature-regions is analyzed for recognition of these critical points as the standard landarks associated with the primary facial features. A number of clinically identified landmarks lie on the facial midline. An efficient algorithm for detection and processing of the midline using a point samplng technique is also presented. The results are matching well with human perception and measurements done manually on the subjects.
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Mohri, Hisashi, Ritsuko Matsumoto, and Yuichi Kaji. "Key predistribution schemes for sensor networks using lines,points over a finite geometry." In 2006 2nd IEEE Workshop on Wireless Mesh Networks. IEEE, 2006. http://dx.doi.org/10.1109/wimesh.2006.288609.
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Hui, S. Y., K. H. Yeung, and K. Y. Wong. "Optimal Placement of Mesh Points in a Wireless Mesh Network Using Multi-path Routing Protocol." In 2008 IFIP International Conference on Network and Parallel Computing (NPC). IEEE, 2008. http://dx.doi.org/10.1109/npc.2008.87.
Full textReports on the topic "MESH POINTS"
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Wettergren, Thomas A. An Adaptive Mesh Technique for Finding the Bistatic Specular Point on a Convex Hull. Fort Belvoir, VA: Defense Technical Information Center, November 1998. http://dx.doi.org/10.21236/ada359258.
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Dong, Wei, Wei Zhang, Jianxu Er, Jiapeng Liu, and Jiange Han. Lesser complications of laryngeal mask airway than endotracheal tubes in pediatric airway management: A review of literature and meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, May 2022. http://dx.doi.org/10.37766/inplasy2022.5.0066.
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Review question / Objective: The relevant expert consensus has not pointed out which ventilation device is better during general anesthesia in the pediatric airway management for elective surgery. Condition being studied: We carried out a keyword search using the terms “layngeal mask, LMA, endotracheal tube, tracheal tube, children, pediatric, anesthesia, RCT, randomized controlled trials, randomized, elective surgery.” In general, searches are developed in MEDLINE in Ovid; Embase.com; the Cochrane Central Register of Controlled Trials (CENTRAL) via the Wiley Interface; Web of Science Core Collection; PubMed restricting to records in the subset “as supplied by publisher” to find references that not yet indexed in MEDLINE; and Google Scholar. When available, these databases were searched using a combination of subject headings (such as MeSH) and filters (such as RCT). We reviewed references of included studies to identify relevant studies. We imposed no language or time restriction. The exact date of the database search is September 1, 2021.We carried out a keyword search using terms “layngeal mask, LMA, endotracheal tube, tracheal tube, children, pediatric, anesthesia, RCT, randomized controlled trials, randomized, elective surgery.”
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Naddafi, Rahmat, Göran Sundblad, Alfred Sandström, Lachlan Fetterplace, Jerker Vinterstare, Martin Ogonowski, and Nataliia Kulatska. Developing management goals and associated assessment methods for Sweden’s nationally managed fish stocks : a project synthesis. Department of Aquatic Resources, Swedish University of Agricultural Sciences, 2023. http://dx.doi.org/10.54612/a.31cfjep2i0.
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This report summarizes and synthesizes results from the Swedish Agency of Marine and Water Management (SwAM, or HaV) funded project “Förvaltningsmål för nationella arter (Management goals for nationally managed species)”. The objectives of the project have been to promote the development of management goals and associated status assessment methods and indicators, as well as reference points, for some nationally managed fish stocks both in coastal as well as freshwater areas. The report focusses largely on species and stocks that can be defined as data-poor. Such stocks are characterised by marked limitations in data availability and/or resources allocated to detailed analytical stock projections. Data-poor stocks also often lack carefully formulated management goals and associated methods and indicators for assessing stock status. In this report, we provide an overview of potential assessment methods and indicators and try to synthesise how they work and what the strengths and weaknesses are by applying them to selected data poor stocks such as pikeperch, pike, whitefish, and vendace. We also discuss how they relate to different potential management goals and provide recommendations for their application. We grouped the indicators and assessment methods by the three categories that are now used in the yearly status assessment framework provided by SLU Aqua (Resursöversikten/Fiskbarometern) – i) mortality, ii) abundance/biomass and iii) size/age structure. The results are also described for these three main categories of assessment indicators. Included is also a status report from a size- and age-based population dynamics model (Stock Synthesis 3) that is being developed for pikeperch in Lake Hjälmaren. An important experience from the project is that to improve the assessment methods for Swedish national fish stocks, it is important that managers develop both general as well as more detailed quantitative goals for the individual stocks. This should ideally be conducted in various forms of collaboration with the main stakeholders and scientists involved with assessment as participatory processes foster legitimacy. Carefully articulated management goals, which are possible to translate into quantitative targets, will facilitate the development of various approaches and methods to monitor stock statuses. Given the strong and complex interactions of fish and their environments it is also important to consider other pressures than fisheries when developing indicators and assessment methods. Our synthesis highlights a number of areas where the assessment of data-poor stocks can be improved: 1. Apply precautionary principles for data-limited stocks, particularly ones that are known to be vulnerable to exploitation. 2. Tailor approaches to how fisheries are managed in Sweden. Swedish nationally managed fish stocks are not managed by quotas (with one exception, vendace in the Bothnian Bay) and do not aim for maximum sustainable yield. Instead, the coastal and inland fisheries are managed by regulating the effort in the small-scale commercial fisheries (number of fishers/licenses and amount of gear). Regulation of recreational and subsistence fisheries effort, in terms of licenses or number of fishers) is not applied, nor possible since the fisheries is lacking obligatory notification and reporting systems. All national fisheries, however, are regulated by various technical measures (closed areas, size-limits, bag-limits, gear restrictions etc). Thus, goals and assessment methods that result in harvest limits or quota recommendations expressed in e.g. biomass/numbers are difficult to use as basis for management. Instead, there is a need for alternative management goals and associated assessment methods. 3. Use best practice methods and indicators and adapt as scientific knowledge is developed. Data-limited methods are developing rapidly, and new methods/approaches are proposed in the scientific literature every year. It is thus important to be updated on the most recent developments. 4. Clearly describe limitations/assumptions of methods used. It is important to be aware of and critically evaluate the assumptions underlying the analyses, and to carefully communicate uncertainty together with the stock status assessment. 5. Be particularly careful with low sample numbers. Many indicators and methods can be applied also on small sample sizes, however, the accuracy and precision of the estimates risk being low in such cases. 6. Accept that there is no "gold standard" for fisheries assessment. Each case study is unique and needs to be balanced against data availability, local needs and other important factors. This also means that analysts need to be careful when using generic reference levels or “borrowing” data from other stocks. 7. If possible, use several different methods/indicators. Although several indicators aim to measure similar aspects of the stock, small methodological differences can support the overall interpretation of individual indicator values. It is particularly important to incorporate many aspects and indicators (size/age/abundance/mortality) in order to produce a balanced assessment. 8. Develop means of communication. Indicators and goals should be easy to understand. However, interpretation of results from multi-indicator frameworks can be challenging. There is thus a need for finding ways of communication that can convey complicated results in a simple-to-understand manner. 9. For details on additional improvements, we refer the reader to the sub-header “recommendations for the future” found under each chapter. The implementation of Stock Synthesis for pikeperch in Lake Hjälmaren showed that it is possible to develop a more ambitious and detailed stock assessment model for a relatively data-poor stock. The model results partly support earlier interpretations of the development of the stock and the importance of the changes in regulations in 2001 (increased minimum size, increased mesh size and reduced mortality of undersized pikeperch). Before the model can be implemented and used for practical management, a number of actions for improvement are needed, which are highlighted in the relevant chapter. The most important next step is establishing management goals and reference levels for this stock. We recommend that such a dialogue is initiated by managers. The fisheries management goals should consider both biomass, fisheries mortality and size-based targets. To conclude, we stress the importance of improving all ongoing aspects related to the assessments of data-poor Swedish stocks. Strong local stocks and sustainable fisheries are vital for a variety of fisheries-related businesses and practices, particularly in rural areas, providing economical and societal value. Fishes also have important roles in aquatic food-webs and it is important that ecological values are managed wisely in order to reach targets for water quality, ecosystem structure and diversity. Given the strong and complex interactions of fish and their environments it is also important to consider other pressures than fisheries when developing indicators and assessment methods.
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Russo, Margherita, Fabrizio Alboni, Jorge Carreto Sanginés, Manlio De Domenico, Giuseppe Mangioni, Simone Righi, and Annamaria Simonazzi. The Changing Shape of the World Automobile Industry: A Multilayer Network Analysis of International Trade in Components and Parts. Institute for New Economic Thinking Working Paper Series, January 2022. http://dx.doi.org/10.36687/inetwp173.
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In 2018, after 25 years of the North America Trade Agreement (NAFTA), the United States requested new rules which, among other requirements, increased the regional con-tent in the production of automotive components and parts traded between the three part-ner countries, United States, Canada and Mexico. Signed by all three countries, the new trade agreement, USMCA, is to go into force in 2022. Nonetheless, after the 2020 Presi-dential election, the new treaty's future is under discussion, and its impact on the automo-tive industry is not entirely defined. Another significant shift in this industry – the acceler-ated rise of electric vehicles – also occurred in 2020: while the COVID-19 pandemic largely halted most plants in the automotive value chain all over the world, at the reopen-ing, the tide is now running against internal combustion engine vehicles, at least in the an-nouncements and in some large investments planned in Europe, Asia and the US. The definition of the pre-pandemic situation is a very helpful starting point for the analysis of the possible repercussions of the technological and geo-political transition, which has been accelerated by the epidemic, on geographical clusters and sectorial special-isations of the main regions and countries. This paper analyses the trade networks emerg-ing in the past 25 years in a new analytical framework. In the economic literature on inter-national trade, the study of the automotive global value chains has been addressed by us-ing network analysis, focusing on the centrality of geographical regions and countries while largely overlooking the contribution of countries' bilateral trading in components and parts as structuring forces of the subnetwork of countries and their specific position in the overall trade network. The paper focuses on such subnetworks as meso-level structures emerging in trade network over the last 25 years. Using the Infomap multilayer clustering algorithm, we are able to identify clusters of countries and their specific trades in the automotive internation-al trade network and to highlight the relative importance of each cluster, the interconnec-tions between them, and the contribution of countries and of components and parts in the clusters. We draw the data from the UN Comtrade database of directed export and import flows of 30 automotive components and parts among 42 countries (accounting for 98% of world trade flows of those items). The paper highlights the changes that occurred over 25 years in the geography of the trade relations, with particular with regard to denser and more hierarchical network gener-ated by Germany’s trade relations within EU countries and by the US preferential trade agreements with Canada and Mexico, and the upsurge of China. With a similar overall va-riety of traded components and parts within the main clusters (dominated respectively by Germany, US and Japan-China), the Infomap multilayer analysis singles out which com-ponents and parts determined the relative positions of countries in the various clusters and the changes over time in the relative positions of countries and their specialisations in mul-tilateral trades. Connections between clusters increase over time, while the relative im-portance of the main clusters and of some individual countries change significantly. The focus on US and Mexico and on Germany and Central Eastern European countries (Czech Republic, Hungary, Poland, Slovakia) will drive the comparative analysis.
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Geologic map of the Pigeon Canyon, Nevershine Mesa, and Snap Point Wilderness Study Areas, Mohave County, Arizona. US Geological Survey, 1986. http://dx.doi.org/10.3133/mf1860b.
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Limnology of Blue Mesa, Morrow Point, and Crystal Reservoirs, Curecanti National Recreation area, during 1999, and a 25-year retrospective of nutrient conditions in Blue Mesa Reservoir, Colorado. US Geological Survey, 2003. http://dx.doi.org/10.3133/wri024199.
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LOCAL BUCKLING BEHAVIORS OF COLD-FORMED CIRCULAR HOLLOW SECTIONS HIGH STRENGTH STEEL STUB COLUMNS BASED ON A HIGH-FIDELITY NUMERICAL MODEL (ICASS’2022). The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.337.
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This paper establishes a high-fidelity numerical model to systematically investigate the local buckling behaviors of cold-formed circular hollow section (CHS) high-strength steel stub columns. Material nonlinearity and geometric nonlinearity are carefully accounted for in the FE model. Based on the Menegotto-Point model, the material constitutive of cold-formed CHS is calibrated considering the characteristics of the curvature of the stress-strain curve. The mesh is uniformly patterned according to the cross-section of the CHSs steel under compression. Subsequently, parametric studies are carried out to study the local buckling mode, buckling strength and ductility of the cold-formed high-strength CHS. The cross-sectional slenderness limit and local buckling strength of CHSs with material strength more than 500 MPa are proposed.
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Mineral resource potential map of the Pigeon Canyon, Nevershine Mesa, and Snap Point Wilderness Study Areas, Mohave County, Arizona. US Geological Survey, 1986. http://dx.doi.org/10.3133/mf1860a.
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Informe sobre o impacto dos cultivos forestais con especies de crecemento rápido no patrimonio natural e cultural de galicia. Consello da Cultura Galega, September 2023. http://dx.doi.org/10.17075/icfecrpncg.2023.
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No mes de setembro do ano 2020 un grupo de asociacións (a Sociedade Histórica e Cultural Coluna Sanfins, a Asociación Sociocultural O Iribio, a Asociación Galega Cova Crea, a Fundación Montescola, a Asociación Amigos e Amigas dos Bosques «O Ouriol do Anllóns» e a Asociación Autonómica Cultural e Ambiental Petón do Lobo) dirixiuse ao Consello da Cultura Galega solicitando: 1.- Que a Comisión Executiva do Consello da Cultura Galega teña a ben a presentación deste escrito e considere solicitar un informe relativo á avaliación do impacto que a expansión incontrolada do eucalipto está a ter sobre: Os bosques formados por especies nativas, fragas ou bosques antigos galegos. O patrimonio arqueolóxico e cultural de Galicia. 2.- A publicación deste informe, coas súas recomendacións e medidas propostas para evitar o dano sobre o patrimonio cultural e natural, para o acceso e maior toma de conciencia da cidadanía galega en relación coa necesidade de protección das fragas e dos xacementos arqueolóxicos de Galicia. Ante estas solicitudes e no contexto de proliferación de plantacións de especies de crecemento rápido que se está a producir en Galicia, mais tamén da demanda social de diferentes colectivos, como as comunidades, o tecido asociativo, as administracións locais e particulares, e de persoas físicas e xurídicas que en gran medida responden á defensa dos valores do territorio, valores estes de tipo social, ambiental e cultural, así como da propia paisaxe, a Comisión Executiva do Consello da Cultura Galega (CCG) acordou en marzo de 2021 a creación dunha Comisión técnica temporal, coordinada por Rebeca Blanco-Rotea e integrada polos seguintes especialistas de diferentes disciplinas: Paula Ballesteros Arias, Eduardo Corbelle Rico, Teresa Nieto Freire (coordinación técnica), Pablo Ramil Rego, Xosé Manuel Santos Solla e Xosé Ignacio Vilaseco Vázquez, á que se encomendou a elaboración dun Informe sobre o impacto dos cultivos forestais con especies de crecemento rápido no patrimonio natural e cultural de Galicia. Os membros e o informe debían atender de forma conxunta as demandas achegadas ao CCG, analizando de forma obxectiva, técnica, plural, rigorosa e construtiva o obxecto destas, a realidade deste tipo de actividade, a afección real ao patrimonio natural e cultural, especialmente ás paisaxes culturais, e facelo de maneira propositiva, é dicir, intentando propor alternativas que melloren a situación do patrimonio en Galicia, especialmente das paisaxes culturais, e minimizando o impacto producido nelas por este tipo de plantacións. Este informe artéllase en varios puntos que analizan a cuestión forestal en Galicia: a conflitividade social arredor das plantacións forestais, a cuestión forestal no contexto das políticas territoriais, os efectos dos cultivos forestais sobre a biodiversidade, o patrimonio cultural do monte, a protección dos bens patrimoniais ante da xestión forestal e o patrimonio como recurso cultural neste contexto, aspectos que aportan unha visión xeral derredor da situación do monte en Galicia e de como lle afectan os cultivos forestais de crecemento rápido. Con todo iso, recóllense unha serie de conclusións que mostran a situación galega, para intentar achegar recomendacións que eviten as afeccións deste tipo de cultivos ao patrimonio cultural e natural na comunidade galega. A elaboración deste informe foi complexa, pois estaba suxeito a unha realidade poliédrica na que se entrecruzan diferentes visións, intereses, necesidades e realidades e foi necesario acadar consensos que tivesen sempre en perspectiva a encomenda do informe e a visión plural e obxectiva dos membros que integraron o equipo de traballo.