Bibliographies thématiques / Spatial and geometric constraints

Littérature scientifique sur le sujet « Spatial and geometric constraints »

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Publié le 7 juillet 2024

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Articles de revues sur le sujet "Spatial and geometric constraints"

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Campeotto, F., A. Dal Palù, A. Dovier, F. Fioretto et E. Pontelli. « A Constraint Solver for Flexible Protein Model ». Journal of Artificial Intelligence Research 48 (30 décembre 2013) : 953–1000. http://dx.doi.org/10.1613/jair.4193.

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This paper proposes the formalization and implementation of a novel class of constraints aimed at modeling problems related to placement of multi-body systems in the 3-dimensional space. Each multi-body is a system composed of body elements, connected by joint relationships and constrained by geometric properties. The emphasis of this investigation is the use of multi-body systems to model native conformations of protein structures---where each body represents an entity of the protein (e.g., an amino acid, a small peptide) and the geometric constraints are related to the spatial properties of the composing atoms. The paper explores the use of the proposed class of constraints to support a variety of different structural analysis of proteins, such as loop modeling and structure prediction. The declarative nature of a constraint-based encoding provides elaboration tolerance and the ability to make use of any additional knowledge in the analysis studies. The filtering capabilities of the proposed constraints also allow to control the number of representative solutions that are withdrawn from the conformational space of the protein, by means of criteria driven by uniform distribution sampling principles. In this scenario it is possible to select the desired degree of precision and/or number of solutions. The filtering component automatically excludes configurations that violate the spatial and geometric properties of the composing multi-body system. The paper illustrates the implementation of a constraint solver based on the multi-body perspective and its empirical evaluation on protein structure analysis problems.
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Wu, Chi-haur, et Chi-cheng Jou. « Design of a Controlled Spatial Curve Trajectory for Robot Manipulations ». Journal of Dynamic Systems, Measurement, and Control 113, no 2 (1 juin 1991) : 248–58. http://dx.doi.org/10.1115/1.2896372.

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For integrating different constraints from robot’s tasks, such as geometry, kinematics, and dynamics, with trajectory planning and robot motion control, a two-layer robot trajectory planning structure is proposed. The structure decomposes the trajectory planning problem into path geometry planning and motion speed planning. By separating speed planning from path geometry planning, two different problems can be solved. The first problem is to incorporate geometric changes of a robot task into both translational and orientational path plannings. By solving it, various spatial curve paths can be planned and the difficulty of predicting rotational motions in the Cartesian space can be removed. The second problem is to incorporate motion constraints into the trajectory planning, such as the constraint of maintaining a desired constant robot speed along any planned geometric path. Through the proposed structure, different robot motion requirements along various spatial curves can be controlled by different speed control functions. To demonstrate the proposed scheme, examples are given.
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Wang, Yao, Shixing Yang, Tao Zhou et Na Li. « Geometric Optimization of Distributed MIMO Radar Systems With Spatial Distance Constraints ». IEEE Access 8 (2020) : 199227–41. http://dx.doi.org/10.1109/access.2020.3034591.

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Rosenberg, S. S., E. E. Kelland, E. Tokar, A. R. De La Torre et J. R. Chan. « The geometric and spatial constraints of the microenvironment induce oligodendrocyte differentiation ». Proceedings of the National Academy of Sciences 105, no 38 (11 septembre 2008) : 14662–67. http://dx.doi.org/10.1073/pnas.0805640105.

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Sapidis, N. S. « Geometric modeling of spatial constraints : objectives, methods and solid-modeling requirements ». Computing 79, no 2-4 (7 mars 2007) : 337–52. http://dx.doi.org/10.1007/s00607-006-0210-2.

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Wang, Wei, Xinyao Tang et Ying Li. « Optimization and Estimation Algorithm of Vehicle Spatial Form Based on Monocular Traffic Camera ». Transportation Research Record : Journal of the Transportation Research Board 2676, no 3 (23 octobre 2021) : 360–70. http://dx.doi.org/10.1177/03611981211051347.

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Accurate and rapid acquisition of vehicle spatial form is of great importance in the fields of intelligent transportation and autonomous driving. However, given the limitations of projective geometry, it is difficult to obtain the 3-D structure of vehicles using monocular cameras. The purpose of this paper is, therefore, to estimate the vehicle spatial form using monocular traffic cameras. Firstly, we establish the camera calibration model of the road scene, and jointly construct the geometric constraint model of the vehicle spatial form by vanishing points. Secondly, the contour and edge constraints of the vehicle are obtained based on Mask R-CNN. Then, based on these constraints, the error constraint function is constructed to calculate the projection error of the vehicle spatial form. Finally, a particle swarm optimization algorithm is used to iteratively optimize the parameters in the constraint space to obtain accurate vehicle spatial form information. Experiments are carried on the BrnoCompSpeed data set and the home-made data set. The experimental results show that the processing time of a single frame is less than 0.5 s and the average accuracy is higher than 94%. Moreover, the proposed algorithm has good robustness to the issue of vehicle occlusion and queuing in the scene, which outperforms existing methods.
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Gorti, Sreenivasa Rao, Salal Humair, Ram D. Sriram, Sarosh Talukdar et Sesh Murthy. « Solving constraint satisfaction problems using ATeams ». Artificial Intelligence for Engineering Design, Analysis and Manufacturing 10, no 1 (janvier 1996) : 1–19. http://dx.doi.org/10.1017/s0890060400001256.

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AbstractThis paper presents an approach to solving constraint satisfaction problems using Asynchronous Teams of autonomous agents (ATeams). The focus for the constraint satisfaction problem is derived from an effort to support spatial layout generation in a conceptual design framework. The constraint specification allows a high-level representation and manipulation of qualitative geometric information. We present a computational technique based on ATeams to instantiate solutions to the constraint satisfaction problem. The technique uses a search for a solution in numerical space. This permits us to handle both qualitative relationships and numerical constraints in a unified framework. We show that simple knowledge, about human spatial reasoning and about the nature of arithmetic operators can be hierarchically encapsulated and exploited efficiently in the search. An example illustrates the generality of the approach for conceptual design. We also present empirical studies that contrast the efficiency of ATeams with a search based on genetic algorithms. Based on these preliminary results, we argue that the ATeams approach elegantly handles arbitrary sets of constraints, is computationally efficient, and hence merits further investigation.
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Werkhoven, Peter, et Jan J. Koenderink. « Visual Size Invariance Does Not Apply to Geometric Angle and Speed of Rotation ». Perception 22, no 2 (février 1993) : 177–84. http://dx.doi.org/10.1068/p220177.

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The ability of humans to visually estimate geometric angle and speed of rotation was examined as a function of the spatial scale of the stimuli. Both properties are objectively invariant at different spatial scales, but the results of experiments show that the judgement of acute geometric angles as well as that of speed of rotation varies strongly and monotonically with the scale of presentation. If the image is magnified, the perceived geometric angle and the perceived speed of rotation increase. If the image is reduced in size, they decrease. This result imposes strong constraints on perceptual theories.
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Wang, Naige, Guohua Cao, Lu Yan et Lei Wang. « Modeling and Control for a Multi-Rope Parallel Suspension Lifting System under Spatial Distributed Tensions and Multiple Constraints ». Symmetry 10, no 9 (18 septembre 2018) : 412. http://dx.doi.org/10.3390/sym10090412.

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The modeling and control of the multi-rope parallel suspension lifting system (MPSLS) are investigated in the presence of different and spatial distributed tensions; unknown boundary disturbances; and multiple constraints, including time varying geometric constraint, input saturation, and output constraint. To describe the system dynamics more accurately, the MPSLS is modelled by a set of partial differential equations and ordinary differential equations (PDEs-ODEs) with multiple constraints, which is a nonhomogeneous and coupled PDEs-ODEs, and makes its control more difficult. Adaptive boundary control is a recommended method for position regulation and vibration degradation of the MPSLS, where adaptation laws and a boundary disturbance observer are formulated to handle system uncertainties. The system stability is rigorously proved by using Lyapunov’s direct method, and the position and vibration eventually diminish to a bounded neighborhood of origin. The original PDEs-ODEs are solved by finite difference method, and the multiple constraints problem is processed simultaneously. Finally, the performance of the proposed control is demonstrated by both the results of ADAMS simulation and numerical calculation.
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Catenacci Volpi, Nicola, et Daniel Polani. « Space Emerges from What We Know—Spatial Categorisations Induced by Information Constraints ». Entropy 22, no 10 (19 octobre 2020) : 1179. http://dx.doi.org/10.3390/e22101179.

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Seeking goals carried out by agents with a level of competency requires an “understanding” of the structure of their world. While abstract formal descriptions of a world structure in terms of geometric axioms can be formulated in principle, it is not likely that this is the representation that is actually employed by biological organisms or that should be used by biologically plausible models. Instead, we operate by the assumption that biological organisms are constrained in their information processing capacities, which in the past has led to a number of insightful hypotheses and models for biologically plausible behaviour generation. Here we use this approach to study various types of spatial categorizations that emerge through such informational constraints imposed on embodied agents. We will see that geometrically-rich spatial representations emerge when agents employ a trade-off between the minimisation of the Shannon information used to describe locations within the environment and the reduction of the location error generated by the resulting approximate spatial description. In addition, agents do not always need to construct these representations from the ground up, but they can obtain them by refining less precise spatial descriptions constructed previously. Importantly, we find that these can be optimal at both steps of refinement, as guaranteed by the successive refinement principle from information theory. Finally, clusters induced by these spatial representations via the information bottleneck method are able to reflect the environment’s topology without relying on an explicit geometric description of the environment’s structure. Our findings suggest that the fundamental geometric notions possessed by natural agents do not need to be part of their a priori knowledge but could emerge as a byproduct of the pressure to process information parsimoniously.
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Thèses sur le sujet "Spatial and geometric constraints"

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Senger, Fabrice. « Dynamique du cytosquelette et polarité cellulaire ». Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV089/document.

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Une cellule reçoit et intègre une multitude de signaux physiques et biochimiques. Elle est capable de sentir et de répondre à ces signaux de sorte que ses fonctions s’accordent avec son environnement. Si l’intégration de ces signaux est hautement régulée par des voies de signalisation et de rétroaction, certaines étapes semblent résulter de processus d’auto-organisation géométrique et mécanique du réseau d’actine. Il est capable de s’auto-assembler et d’adopter différentes architectures. Celles-ci sont autant de modules qui coexistent dans la cellule avec une claire ségrégation spatiale et fonctionnelle. Notamment, le cytosquelette d’actine participe à l’intégration des signaux encodés par la matrice extracellulaire. Cette intégration suppose entre autre, une régulation des forces de tension entre la cellule et son environnement impliquant le cytosquelette d’actine, les adhésions cellulaire et la matrice. Afin d’explorer ces mécanismes, nous avons eu recours à des techniques avancées de micropatterning, de mesure de force de traction cellulaire et de microdissection laser. Nous avons ainsi montré en réprimant l’expression de l’ alpha-actinine, une des principales protéines de réticulation du cytosquelette d’actine, que la connectivité du réseau d’actine était essentielle à l’intégration des signaux émanant de la matrice extracellulaire. Elle participe à l’évaluation de la rigidité de la matrice et au mécanisme de migration dirigé haptotactique. Elle participe donc potentiellement aux mécanismes de différentiation cellulaire et au maintien de la polarité cellulaire. Dans le même esprit nous avons pris part à une étude portant sur l’organisation et la maturation des adhésions cellulaires, en participant à la caractérisation d’une protéine d’adhésion Kank2. Nous avons ainsi pu démontrer le rôle essentiel de cette protéine dans le phénomène de rigidity sensing. L’ensemble de l’étude ayant montré l’implication de cette protéine dans le processus de maturation des adhésions cellulaires et de mécano-transduction
Cells sense and integrate a wealth of mechanical and biochemical signals. Signal integration is part of a process, which ensures that cellular functions are in accordance with the extracellular environment. While these processes are highly regulated by biochemical and mechanical signalling and feedback loops, some of the fundamental processes appear to rely on actin cytoskeleton autoassembly giving raise to modules with defined geometrical and mechanical properties. Thus the actin cytoskeleton is a modular architecture, and the modules co-exist within the cell with spatial and functional specificity. The actin cytoskeleton, notably, is involved in cell/matrice signalling. This interaction relies mainly on mechanical signalling involving the actin cytoskeleton, cell/matrix adhesions and the extracellular matrix. To characterize these mechanisms we took advantage of advanced micropatterning techniques, traction force measurements and laser microdissection. By downregulating the expression of α-actinin, one of the main actin crosslinking proteins, we demonstrated that actin cytoskeleton connectivity is essential for proper integration of cell/matrix signalling. Connectivity is essential for rigidity sensing and haptotaxis by ensuring balanced force distribution through the whole cell. Therefore connectivity might be crucial for cell differentiation processes and cellular polarity. Further, in the context of a collaborative project, we have contributed to the characterization of a novel cell adhesion protein, namely, Kank2. We showed, by traction force measurements, that this protein is essential for rigidity sensing. Globally this study demonstrated the implication of Kank2 in cell adhesion maturation and mecanotransduction
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Alborzi, Houman. « Geometric issues in spatial indexing ». College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4057.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.
Thesis research directed by: Computer Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Ralley, Richard. « Spatial constraints on attention ». Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302301.

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Dai, Xiangyuan. « Spatial queries based on non-spatial constraints ». Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38436395.

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Dai, Xiangyuan, et 戴祥元. « Spatial queries based on non-spatial constraints ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38436395.

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Coulter, Stewart. « Representation of geometric constraints in parametric synthesis ». Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/17982.

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Ma'ani-Hessari, Nason J. « Design of quadruplex DNA through geometric constraints ». Thesis, University of Ulster, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.551558.

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This thesis is concerned with the rational design of a group of DNA higher order architectures known as quadruplex DNA. Quadruplex DNA is comprised of a stem of stacking guanine tetrads linked by loops comprised of single stranded DNA. Due to the different combinations of loop types possible, it has great structural diversity and has potential nanotechnological and biological applications. Currently, only a few loop combinations, or topologies are known. Those that have been determined experimentally were not explicitly designed. Using a geometric formalism, the sum of currently available knowledge on quadruplex folding was used to create a set of parameters for the design of novel quadruplex architectures. We present the proof of principle for rational design of said structures, through making the novel topology (-pd+l) and the (G:C:G:C) tetrad- containing topology -(Ppp). We apply this principle to interpret thermal difference spectra signatures of a number of designed quadruplexes. Finally, we show that such novel quadruplexes can be used as building blocks for nanowires. This thesis therefore describes the proof of principle of design, means to expediate design, and an example application of design, of quadruplex nucleic acids. Through achieving these three aims, we present the feasibility of designing novel quadruplexes to be used as nanotechnological or medical devices.
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Wilczkowiak, Marta. « 3D modelling from images using geometric constraints ». Grenoble INPG, 2004. http://www.theses.fr/2004INPG0034.

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Phipps, Richard L. « Some Geometric Constraints on Ring-Width Trend ». Tree-Ring Society, 2005. http://hdl.handle.net/10150/262639.

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Simulations of tree rings from trees of undisturbed forest sites are used to describe natural, long-term width trends. Ring-width trends of canopy-sized white oak are simulated from regressions of BAI (ring area) data of real trees. Examples are given of a tree from a typical re-growth forest in Illinois and of a more slowly growing tree from an old-growth forest in Kentucky. The long-term width trend was simulated as being toward constant ring width regardless of growth rate of the tree. Conditions by which either increasing or decreasing ring-width trends could be simulated from the same linear BAI trend are examined. I conclude that curvilinear width trends, either increasing or decreasing, represent width adjustments to changes in growth rate (BAI trend) after which the width trend stabilizes to a near-constant value. Interpretation of ring-width trends of trees from undisturbed stands may be useful in assessing stand disturbance history.
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Dodwell, Timothy J. « Multilayered folding with constraints ». Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549892.

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In the deformation of layered materials such as geological strata, or stacks of paper, mechanical properties compete with the geometry of layering. Smooth, rounded corners lead to voids between layers, while close packing leads to geometrically induced curvature singularities. When creation of voids is penalized by external pressure, the system trades off these competing effects, leading to various accommodating formations. Three two dimensional energy based nonlinear models are presented to describe the formation of voids at areas of intense geological folding. For each model the layers are assumed to be flexible elastic beams under hard unilateral contact constraint; which are solved as quasi-static obstacle problems with a free boundary. In each case an application of Kuhn-Tucker theory leads to representation as a nonlinear fourth order differential equation. Firstly a single layered model for voiding is presented. An elastic layer is forced into a V-shaped singularity by a uniform overburden pressure, where the fourth order free boundary problem is shown to have a unique, convex, symmetric solution. Drawing parallels with the Kuhn-Tucker theory, virtual work and ideas of duality, the physical significance of this differential equation is emphasised. Finally, appropriate scaling of either the potential energy or the differential equation shows the solutions scale to a single parametric group, for which the size of the void scales inversely with the ratio of overburden pressure to bending stiffness of the layer. Common to structural geology, one or several especially thick layers can dominate the deformation process. As a result, the remaining weak layers must accommodate into the geometry imposed by these competent layers. The second model, extends the first by introducing a plastic hinge to replicate the geometry imposed by the competent layer, and also axial springs to resist the slip over the limbs. The equilibrium equations for the system are investigated using the mathematical techniques developed for the first model. Under rigid loading the system may snap from an initially flat state to a convex voiding solution, as seen in the first model. However, if resistance to slip is high, the slightest imperfection causes the system to jump to a convoluted up-buckled solution, following a de-stiffened path to a point of self contact. These solutions have similarities with the delamination of carbon fibre composites. Finally, we extend the two single layered models to a simple multilayered model, which describes the periodic formation of voids in a chevron fold. The model shows that in the limit of high overburden pressures solutions form voids every layer, producing straight limbs punctured by sharp corners. This analysis shows good agreement when compared with recent experiments. This work provides the basis for future work on the buckling of thin multilayer assemblies in which voids may develop, and emphasizes the importance of the intricate nonlinear constraints of layers fitting together in multilayered folds.
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Livres sur le sujet "Spatial and geometric constraints"

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Shufelt, Jefferey. Geometric Constraints for Object Detection and Delineation. Boston, MA : Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-5273-4.

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Shufelt, Jefferey. Geometric constraints for object detection and delineation. Boston : Kluwer Academic Publishers, 2000.

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Grimson, William Eric Leifur. Object recognition by computer : The role of geometric constraints. Cambridge, Mass : MIT Press, 1990.

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Govaerts, Jan. Hamiltonian quantisation and constrained dynamics. Leuven (Belgium) : Leuven University Press, 1991.

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NATO Advanced Study on Propagation of Correlations in Constrained Systems (1990 Cargèse, France). Correlations and connectivity : Geometric aspects of physics, chemistry, and biology. Dordrecht : Kluwer Academic Publishers, 1990.

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Ness, Daniel. Knowledge under construction : The importance of play in developing children's spatial and geometric thinking activities. Lanham, Md : Rowman & Littlefield, 2007.

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Landsat-4 Science Characterization Early Results Symposium (1983 Greenbelt, Md.). Landsat-4 science characterization early results : Proceedings of the Landsat-4 Science Characterization Early Results Symposium, February 22-24, 1983, held at NASA Goddard Space Flight Center, Greenbelt, Maryland. Sous la direction de Barker John L, United States. National Aeronautics and Space Administration et Landsat-4 Early Results Symposium (1983 : Greenbelt, Md.). Washington, D.C : National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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L, Barker John, et United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch, dir. Landsat-4 science characterization early results. [Washington, D.C.] : National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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Landsat-4 Science Characterization Early Results Symposium (1983 Greenbelt, Md.). Landsat-4 science characterization early results : Proceedings of the Landsat-4 Science Characterization Early Results Symposium, February 22-24, 1983, held at NASA Goddard Space Flight Center, Greenbelt, Maryland. Sous la direction de Barker John L, United States. National Aeronautics and Space Administration et Landsat-4 Early Results Symposium (1983 : Greenbelt, Md.). Washington, D.C : National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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L, Barker John, et United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., dir. Landsat-4 science characterization early results. [Washington, D.C.] : National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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Chapitres de livres sur le sujet "Spatial and geometric constraints"

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Yang, Lu. « Solving Spatial Constraints with Generalized Distance Geometry ». Dans Distance Geometry, 95–120. New York, NY : Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-5128-0_6.

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Knura, Martin, et Jochen Schiewe. « Improvement of Task-Oriented Visual Interpretation of VGI Point Data ». Dans Volunteered Geographic Information, 199–217. Cham : Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-35374-1_10.

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AbstractVGI is often generated as point data representing points of interest (POIs) and semantic qualities (such as accident locations) or quantities (such as noise levels), which can lead to geometric and thematic clutter in visual presentations of regions with numerous VGI contributions. As a solution, cartography provides several point generalization operations that reduce the total number of points and therefore increase the readability of a map. However, these operations are applied rather general and could remove specific spatial pattern, possibly leading to false interpretations in tasks where these spatial patterns are of interest. In this chapter, we want to tackle this problem by defining task-oriented sets of map generalization constraints that help to maintain spatial pattern characteristics during the generalization process. Therefore, we conduct a study to analyze the user behavior while solving interpretation tasks and use the findings as constraints in the following point generalization process, which is implemented through agent-based modeling.
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Zhao, Yisi, Xueming Qian et Tingting Mu. « Image Taken Place Estimation via Geometric Constrained Spatial Layer Matching ». Dans MultiMedia Modeling, 436–46. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14442-9_49.

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Geerts, Floris, et Bart Kuijpers. « Real Algebraic Geometry and Constraint Databases ». Dans Handbook of Spatial Logics, 799–856. Dordrecht : Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-5587-4_13.

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Hoffmann, Christoph M., et Bo Yuan. « On Spatial Constraint Solving Approaches ». Dans Automated Deduction in Geometry, 1–15. Berlin, Heidelberg : Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/3-540-45410-1_1.

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Carfora, Mauro, et Annalisa Marzuoli. « Geometric Preliminaries ». Dans Einstein Constraints and Ricci Flow, 11–43. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8540-9_2.

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Kaplan, Craig S. « Depiction Using Geometric Constraints ». Dans Computational Imaging and Vision, 167–87. London : Springer London, 2012. http://dx.doi.org/10.1007/978-1-4471-4519-6_9.

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Papadimitriou, Fivos. « The Geometric Basis of Spatial Complexity ». Dans Spatial Complexity, 39–50. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-59671-2_3.

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Noort, Alex, Rafael Bidarra et Willem F. Bronsvoort. « Satisfying Interaction Constraints ». Dans From Geometric Modeling to Shape Modeling, 49–64. Boston, MA : Springer US, 2002. http://dx.doi.org/10.1007/978-0-387-35495-8_5.

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Shufelt, Jefferey. « Geometric Constraints for Hypothesis Generation ». Dans Geometric Constraints for Object Detection and Delineation, 75–109. Boston, MA : Springer US, 2000. http://dx.doi.org/10.1007/978-1-4615-5273-4_4.

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Actes de conférences sur le sujet "Spatial and geometric constraints"

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Yu, Hang, Xiangjie Yin, Ruiheng Zhang, Chenyang Li et Haoran Jiang. « Spatial Geometric Constraints based Iterative Clustering Algorithm ». Dans 2021 5th Asian Conference on Artificial Intelligence Technology (ACAIT). IEEE, 2021. http://dx.doi.org/10.1109/acait53529.2021.9731164.

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Robson, Nina, et Aaron Lee. « Spatial Mechanism-Environment Contact Geometric Models ». Dans ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-71380.

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Abstract This work proposes a theoretical foundation for a general spatial geometric mechanism-environment contact model. In the proposed model the curvature of the environment in the vicinity of the contact is approximated by a number of spherical surfaces with known radii of curvature that constrain/define the movement of the body. We show how the modeled body-environment contact and curvature constraints can be transformed into conditions on spatial velocity and acceleration (i.e. first and second order effects) of certain points of the moving body that can be incorporated in the kinematic task for designing spatial mechanisms. Further, we explore the exact synthesis of a spatial six degrees-of-freedom TPS kinematic chain which end-effector maintains contact with objects in the environment and varies orientation in the vicinity of a contact location. It is discussed how the higher order motion constraints allow for the introduction of kinematic task variations in the vicinity of a contact, resulting in different behaviors of the designed spatial mechanism. The theoretical foundation presented in this paper is crucial in gaining understanding of the constraints in describing mechanism-environment interactions in the vicinity of a contact and is a new contribution.
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Srinivasan, Hari, et Rajit Gadh. « Selective Disassembly of Components With Geometric Constraints ». Dans ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/dfm-8961.

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Abstract This paper analyzes the problem of global disassembly of a selected component from a geometrically constrained assembly. The geometric constraints are (I) spatial constraints due to the three-dimensional geometric interactions between the components in an assembly and (II) user-defined constraints, such as grouping of components as subassemblies and directional constraints on component geometry. A new algorithm has been proposed to determine the disassembly sequence for a selected component, minimizing the number of component removals. The algorithm analyzes both the spatial constraints of the assembly geometry and the user-defined constraints in evaluating the accessibility of components, which is followed by determining the topological disassembly ordering of the components to evaluate an optimal sequence. Preliminary implementation results of the algorithm, and discussions on the applicability of the algorithm to maintenance, recycling and assembling applications, are presented.
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Li, Xiangyun, Q. J. Ge et Feng Gao. « A Unified Algorithm for Geometric Design of Platform Linkages With Spherical and Plane Constraints ». Dans ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-35218.

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This paper studies the constrained motion of a rigid body such that one or more of its points stays on a sphere or a plane. It extends Innocenti’s spatial Burmester problem from purely spherical constraints to include any combination of spherical and planar constraints for seven position synthesis of a spatial rigid body. The present paper provides a unified formulation using homogeneous coordinates and dual quaternions for simultaneous dimensional and type synthesis of spatial platform linkages and manipulators involving spherical and planar constraints. The algorithm is an extension of our previous work on unified solution for planar Burmester problem for geometric synthesis of planar dyads involving a combination of revolute and prismatic joints.
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Xie, Yonghua, et Micheal Oheigeartaigh. « 3D Pollen particle recognition based on spatial geometric constraints histogram descriptors ». Dans 2010 3rd International Congress on Image and Signal Processing (CISP). IEEE, 2010. http://dx.doi.org/10.1109/cisp.2010.5647888.

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Nederbragt, Walter W., et Bahram Ravani. « Kinematic Fixturing With Respect to a Plane Using Contact Sensing ». Dans ASME 1998 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/detc98/mech-5907.

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Abstract This paper presents a method for determining the location of geometric elements that compose the external features of referencing fixtures. Since in most applications parts that are handled in robotic work-cells are on a worktable or a floor, this paper focuses on fixture geometries that reside on a plane of known location. The location of the unknown geometric elements are found using contacts to the geometric elements and spatial constraints between the geometric elements. Geometric equations for contacts between lines, planes, points, spheres, and cylinders are derived. Spatial constraint equations are also derived. An algorithm is given for locating the geometric elements that form the fixture. The algorithm uses the contact equations and spatial constraint equations to locate the geometric elements. To illustrate the use of this algorithm, two examples are described in detail.
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Wang, Anjie, Yongbin Gao, Zhijun Fang, Xiaoyan Jiang, Shanshe Wang, Siwei Ma et Jenq-Neng Hwang. « Unsupervised Learning of Depth and Ego-Motion with Spatial-Temporal Geometric Constraints ». Dans 2019 IEEE International Conference on Multimedia and Expo (ICME). IEEE, 2019. http://dx.doi.org/10.1109/icme.2019.00309.

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Nisbett, J. Keith, et T. J. Lawley. « The Geometric Generation of the Joint Loci of Spatial Dyads With Axis Joints ». Dans ASME 1992 Design Technical Conferences. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/detc1992-0423.

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Abstract The geometric aspects of Burmester theory, as used in planar four-bar linkage synthesis, are examined to define a general procedure which is applied to the generation of the joint loci of spatial dyads with axis joints. The joints are geometrically related to the screw axes of the prescribed motion, by means of a screw triangle. The geometric relationships are typically separated into several geometric constraints. Each geometric constraint is considered separately to generate the loci of lines representing joint axes which satisfy the constraint. Combining the loci from each constraint produces a single loci of all the possible fixed or moving joints. The geometric approach is shown to have several benefits not obtained in numerical and pure analytical techniques, especially in relating the characteristics of the loci to the physical linkage and its required motion.
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Zhou, Hong, et Kwun-Lon Ting. « Geometric Synthesis of Spatial Compliant Mechanisms Using Three-Dimensional Wide Curves ». Dans ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/detc2008-49047.

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A three-dimensional wide curve is a spatial curve with variable cross sections. This paper introduces a geometric synthesis method for spatial compliant mechanisms by using three-dimensional wide curves. In this paper, every connection in a spatial compliant mechanism is represented by a three-dimensional wide curve and the whole spatial compliant mechanism is modeled as a set of connected three-dimensional wide curves. The geometric synthesis of a spatial compliant mechanism is considered as the generation and optimal selection of control parameters of the corresponding three-dimensional parametric wide curves. The deformation and performance of spatial compliant mechanisms are evaluated by the isoparametric degenerate-continuum nonlinear finite element procedure. The problem-dependent objectives are optimized and the practical constraints are imposed during the optimization process. The optimization problem is solved by the MATLAB constrained nonlinear programming algorithm. The effectiveness of the proposed geometric procedures is verified by the demonstrated examples.
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Ge, Jintian, Yanxin Zhou, Baichuan Lou et Chen Lv. « Automatic Spatial Radar Camera Calibration via Geometric Constraints with Doppler-Optical Flow Fusion ». Dans 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). IEEE, 2023. http://dx.doi.org/10.1109/iros55552.2023.10342101.

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Rapports d'organisations sur le sujet "Spatial and geometric constraints"

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Yan, Yujie, et Jerome F. Hajjar. Automated Damage Assessment and Structural Modeling of Bridges with Visual Sensing Technology. Northeastern University, mai 2021. http://dx.doi.org/10.17760/d20410114.

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Recent advances in visual sensing technology have gained much attention in the field of bridge inspection and management. Coupled with advanced robotic systems, state-of-the-art visual sensors can be used to obtain accurate documentation of bridges without the need for any special equipment or traffic closure. The captured visual sensor data can be post-processed to gather meaningful information for the bridge structures and hence to support bridge inspection and management. However, state-of-the-practice data postprocessing approaches require substantial manual operations, which can be time-consuming and expensive. The main objective of this study is to develop methods and algorithms to automate the post-processing of the visual sensor data towards the extraction of three main categories of information: 1) object information such as object identity, shapes, and spatial relationships - a novel heuristic-based method is proposed to automate the detection and recognition of main structural elements of steel girder bridges in both terrestrial and unmanned aerial vehicle (UAV)-based laser scanning data. Domain knowledge on the geometric and topological constraints of the structural elements is modeled and utilized as heuristics to guide the search as well as to reject erroneous detection results. 2) structural damage information, such as damage locations and quantities - to support the assessment of damage associated with small deformations, an advanced crack assessment method is proposed to enable automated detection and quantification of concrete cracks in critical structural elements based on UAV-based visual sensor data. In terms of damage associated with large deformations, based on the surface normal-based method proposed in Guldur et al. (2014), a new algorithm is developed to enhance the robustness of damage assessment for structural elements with curved surfaces. 3) three-dimensional volumetric models - the object information extracted from the laser scanning data is exploited to create a complete geometric representation for each structural element. In addition, mesh generation algorithms are developed to automatically convert the geometric representations into conformal all-hexahedron finite element meshes, which can be finally assembled to create a finite element model of the entire bridge. To validate the effectiveness of the developed methods and algorithms, several field data collections have been conducted to collect both the visual sensor data and the physical measurements from experimental specimens and in-service bridges. The data were collected using both terrestrial laser scanners combined with images, and laser scanners and cameras mounted to unmanned aerial vehicles.
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Hsieh, Chang-Tai, et Enrico Moretti. Housing Constraints and Spatial Misallocation. Cambridge, MA : National Bureau of Economic Research, mai 2015. http://dx.doi.org/10.3386/w21154.

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Jiang, Jiachen, Jiabei Wu, Jue Zhou, Yaobin Chen, Vincent G. Duffy et Renran Tian. Geometric Constraints and Visual Field Related to Speed Management. Purdue University, 2024. http://dx.doi.org/10.5703/1288284317735.

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This study investigates the challenges inherent in rural arterial roads and highways connecting small towns and cities in Indiana. Despite their pivotal role in transportation and development, these roads often experience a high frequency of traffic accidents attributed to speeding, particularly at transition areas from high-speed to low-speed roads. To address this issue, this study investigated cost-efficient and effective speed management countermeasures. This study emphasized the importance of considering cost-efficient and effective speed management strategies, with a focus on roadside vegetation and lane widths near small-town entrances on arterial roads and highway ramps. Proposing four countermeasures for each scenario—such as large spacing bush, small spacing bush, hedge, and narrow lane width for arterial roads or a delineator for highway exit ramps—the investigation employed driving simulator studies involving sixty human subjects to assess the individual and interactive effects of these interventions. The results on driving speed and deceleration rate show that specific combinations of narrow lanes and roadside vegetation were effective in mitigating speeding on arterial roads and highway ramps, especially during the transition zones. The study also revealed that the speed reduction effects of these countermeasures do not persist in post-countermeasure segments, which reduce the boarder impacts of these interventions. The research underscores the importance of a targeted and context-aware approach in selecting and implementing speed management measures and emphasized the need for tailored interventions based on the specific characteristics of each roadway type and scenario.
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Parikh, Jo A., et Anne Werkheiser. Incorporating Geometric Constraints into Rule-Based Systems Using Nonlinear Optimization. Fort Belvoir, VA : Defense Technical Information Center, janvier 1994. http://dx.doi.org/10.21236/ada275093.

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Zhao, Jianmin, et Norman I. Badler. Real Time Inverse Kinematics with Joint Limits and Spatial Constraints. Fort Belvoir, VA : Defense Technical Information Center, janvier 1989. http://dx.doi.org/10.21236/ada220462.

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Harrison, Tracy. Visualizing Complexity : A Spatial Analysis of Decorative Geometric Pattern in the Islamic World, 900-1400 AD. Portland State University Library, janvier 2000. http://dx.doi.org/10.15760/etd.2431.

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Christie, Benjamin, Jordan Klein, Anton Netchaev et Garry Glaspell. Integrating MOVEit motion constraints on a novel robotic manipulator. Engineer Research and Development Center (U.S.), novembre 2023. http://dx.doi.org/10.21079/11681/47845.

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MOVEit, a widely used Robot Operating System framework, plans composite tasks, where the high-level sequence of actions is fixed and known in advance. However, these tasks need to be tailored and adapted to the environmental context. This framework uses custom trajectory planners, known as controllers, to solve goals that are fully defined within the configuration space. Libraries, such as the Open Motion Planning Library, provide a collection of motion planners that can solve task-space goals. An exact spatial and joint replication of the robotic manipulator’s mechanics, typically Universal Robot Description Format and Semantic Robot Description Format files, is required. Common arms such as the Panda-Manipulator and OpenMANIPULATOR-X provide these files in their respective public repositories, but custom arms require significant modification or even a complete rewrite of these files.
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Wilson, D., Matthew Kamrath, Caitlin Haedrich, Daniel Breton et Carl Hart. Urban noise distributions and the influence of geometric spreading on skewness. Engineer Research and Development Center (U.S.), novembre 2021. http://dx.doi.org/10.21079/11681/42483.

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Statistical distributions of urban noise levels are influenced by many complex phenomena, including spatial and temporal variations in the source level, multisource mixtures, propagation losses, and random fading from multipath reflections. This article provides a broad perspective on the varying impacts of these phenomena. Distributions incorporating random fading and averaging (e.g., gamma and noncentral Erlang) tend to be negatively skewed on logarithmic (decibel) axes but can be positively skewed if the fading process is strongly modulated by source power variations (e.g., compound gamma). In contrast, distributions incorporating randomly positioned sources and explicit geometric spreading [e.g., exponentially modified Gaussian (EMG)] tend to be positively skewed with exponential tails on logarithmic axes. To evaluate the suitability of the various distributions, one-third octave band sound-level data were measured at 37 locations in the North End of Boston, MA. Based on the Kullback-Leibler divergence as calculated across all of the locations and frequencies, the EMG provides the most consistently good agreement with the data, which were generally positively skewed. The compound gamma also fits the data well and even outperforms the EMG for the small minority of cases exhibiting negative skew. The lognormal provides a suitable fit in cases in which particular non-traffic noise sources dominate.
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Lauth, Timothy, David Biedenharn, Travis Dahl, Casey Mayne, Keaton Jones, Charles Little, Joseph Dunbar, Samantha Lucker et Nalini Torres. Technical assessment of the Old, Mississippi, Atchafalaya, and Red (OMAR) Rivers : geomorphic assessment. Engineer Research and Development Center (U.S.), août 2022. http://dx.doi.org/10.21079/11681/45143.

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This report documents the geomorphic assessment component of the Old River, Mississippi River, Atchafalaya River, and Red River System Technical Assessment. The overall objectives of the geomorphic assessment are to utilize all available data to document the historic trends in hydrology, sedimentation, and channel geometry for the rivers in the vicinity of the Old River Control Complex and to summarize the changes observed at locations where repetitive datasets exist and at key reaches that are determined during the study. The geomorphic assessment tasks include data compilation, geometric data analysis, gage and discharge analysis, dredge record analysis, sediment data analysis, development of an events timeline, and integration of results. Geomorphic reaches were developed, and the morphological trends during different time periods were identified. The geomorphic assessment highlighted the importance of considering spatial and temporal variability when assessing morphological trends.
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Johnny, Teneisha, et Mark D. Wenner. Tourism and Ecotourism Development in Guyana : Issues and Challenges and the Critical Path Forward. Inter-American Development Bank, décembre 2015. http://dx.doi.org/10.18235/0009267.

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Guyana has high potential to develop a nature-based tourist niche market and help diversify its economic base, which now depends on the export of primary commodities. Despite many natural attractions, Guyana is still at a nascent stage of nature-based development relying on primary factors for tourism development as opposed to thorough planning, focused investments, and aggressive marketing efforts. Other segments of traditional tourism development such as business and leisure also are undeveloped and little studied. The tourism sector in general faces many constraints, such as high air travel cost, inadequate infrastructure, a slew of small-scale lodging properties that are not graded or certified, lack of marketing, and limited government budgetary outlays and incentives that would serve to stimulate development of the sector. Some important steps have been taken to improve competitiveness of the sector, but still a critical mass of interventions has not been realized that can lead to a dramatic transformation. This paper reviews the main issues and challenges and posits that critical path modeling, mathematical programming and spatial economic analysis could be used to identify two or three of the most binding constraints that should be addressed first given budgetary limitations and low levels of private sector investments.
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