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Wyświetlanie 1-15 z 1394
Tytuł:
Recognizing Sharp Features of 2-D Shapes
Autorzy:
Gewali, L.
Scanlan, J. P.
Powiązania:
https://bibliotekanauki.pl/articles/226950.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
shape recognition
shape similarity
boundary approximation
shape decomposition
shape simplification
Opis:
We present an efficient algorithm for recognizing and extracting sharp-features from complex polygonal shapes. The algorithm executes in O(n²) time, where n is the number of vertices in the polygon. Sharp-feature extraction algorithms can be useful as a pre-processing step for measuring shape-similarity between polygonal shapes.
Źródło:
International Journal of Electronics and Telecommunications; 2010, 56, 2; 153-156
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simultaneous shape and mesh quality optimization using pre-shape calculus
Autorzy:
Luft, Daniel
Schulz, Volker
Powiązania:
https://bibliotekanauki.pl/articles/2183472.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape optimization
mesh quality
mesh deformation method
shape calculus
Opis:
Computational meshes arising from shape optimization routines commonly suffer from decrease of mesh quality or even destruction of the mesh. In this work, we provide an approach to regularize general shape optimization problems to increase both shape and volume mesh quality. For this, we employ pre-shape calculus as established in Luft and Schulz (2021). Existence of regularized solutions is guaranteed. Further, consistency of modified pre-shape gradient systems is established. We present pre-shape gradient system modifications, which permit simultaneous shape optimization with mesh quality improvement. Optimal shapes to the original problem are left invariant under regularization. The computational burden of our approach is limited, since additional solution of possibly larger (non-)linear systems for regularized shape gradients is not necessary. We implement and compare pre-shape gradient regularization approaches for a 2D problem, which is prone to mesh degeneration. As our approach does not depend on the choice of metrics representing shape gradients, we employ and compare several different metrics.
Źródło:
Control and Cybernetics; 2021, 50, 4; 473--520
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The shape genus of a shape map
Autorzy:
Čerin, Zvonko
Powiązania:
https://bibliotekanauki.pl/articles/725165.pdf
Data publikacji:
1984
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Źródło:
Colloquium Mathematicum; 1984, 48, 1; 35-47
0010-1354
Pojawia się w:
Colloquium Mathematicum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical properties and advanced subjects in shape memory alloys and polymers
Autorzy:
Matsui, R.
Takeda, K.
Tobushi, H.
Pieczyska, E. A.
Powiązania:
https://bibliotekanauki.pl/articles/281495.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
shape memory alloy
shape memory polymer
functionally-graded shape memory material
shape memory composite
Opis:
Advanced subjects in mechanical properties of shape memory alloys and polymers are discussed. In the subloop loading under a stress-controlled condition of the shape memory alloy, the transformation-induced stress relaxation appears due to variation in temperature. The enhancement of corrosion and corrosion fatigue life of the shape memory alloy is discussed. The development of a functionally-graded shape memory alloy and polymer is expected to obtain better performance. Three-way motion appears in the shape memory composite with the shape memory alloy and polymer.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 2; 447-456
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Zernike Moments to the problem of General Shape Analysis
Autorzy:
Frejlichowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/206416.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
Zernike moments
general shape analysis
shape description
Opis:
The Zernike Moments (ZM) have been successfully applied to the problem of shape recognition. Their properties allow for solving some fundamental problems in this task. Amongst them the most important one is the invariance to rotation, scaling, translation, and reflectional symmetry. Moreover, the obtained representation can vary according to the level of generalisation of a shape. For this reason in the paper the application of the ZM to the problem of General Shape Analysis (GSA) is proposed and experimentally investigated. The GSA problem is similar to the recognition and retrieval of shapes. However, only the most general classes of shapes (e.g. square, triangle, circle, ellipse) are assumed to perform the role of the basic templates. Moreover, the processed object does not have to belong to any of the template classes, but may be only similar to one of them. This enables us to receive the most general information about a shape, e.g. how square, triangular, round, elliptical, etc. it is. In the paper, in order to evaluate the Zernike Moments applied to the problem of GSA, the performance of this shape descriptor is compared with the results provided by nearly two hundred humans and collected by means of appropriate inquiry forms.
Źródło:
Control and Cybernetics; 2011, 40, 2; 515-526
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Use of Resistance Sensors to Measurement of Shape Charge Parameters
Autorzy:
Wiśniewski, A.
Powiązania:
https://bibliotekanauki.pl/articles/358447.pdf
Data publikacji:
2011
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
sensors
shape charge
explosives
shape charge jet
Opis:
In the article different methods of measurement of the collapsing liner parameters and the formation of the shape charge jet by resistance sensor which was placed inside the shape charge are presented. The speed and acceleration change while reducing of resistance sensor length for shape charge in casing and without it for the different angles of the shape charge liner is analyzed. The resistance sensor placed in the shape charge liner permitted to register the parameters which cannot be obtained by the X-ray impulse apparatus. By the resistance sensor placed at the angle to the shape charge axis or perpendicular to the internal surface of the shape charge liner, the reducing shape charge liner parameters were registered. The resistance sensor placed on the shape charge axis enabled to register the parameters of the jet forming in the shape charge. In case of placing of resistance sensor on shape charge casing, the graphs become more stable in comparison with the graphs obtained when resistance sensor was placed inside shape charge.
Źródło:
Central European Journal of Energetic Materials; 2011, 8, 2; 131-141
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Hurwitz – Radon matrices in shape representation
Autorzy:
Jakóbczak, D.
Powiązania:
https://bibliotekanauki.pl/articles/117952.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Promocji Wiedzy
Tematy:
shape representation
curve interpolation
contour reconstruction
shape coefficient
Hurwitz-Radon matrices
Opis:
Computer vision needs suitable methods of shape representation and contour reconstruction. One of them, invented by the author and called method of Hurwitz-Radon Matrices (MHR), can be used in representation and reconstruction of shapes of the objects in the plane. Proposed method is based on a family of Hurwitz-Radon (HR) matrices. The matrices are skew-symmetric and possess columns composed of orthogonal vectors. Shape is represented by the set of nodes. It is shown how to create the orthogonal and discrete OHR operator and how to use it in a process of shape representation and reconstruction. MHR method is interpolating the curve point by point without using any formula or function.
Źródło:
Applied Computer Science; 2010, 6, 1; 63-74
1895-3735
Pojawia się w:
Applied Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On stability analysis in shape optimisation : critical shapes for Neumann problem
Autorzy:
Dambrine, M.
Sokolowski, J.
Żochowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/970525.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
optymalizacja kształtu
analiza stabilności
gradient kształtu
shape optimisation
stability analysis
shape gradient
shape Hessian
Opis:
The stability issue of critical shapes for shape optimization problems with the state function given by a solution to the Neumann problem for the Laplace equation is considered. To this end, the properties of the shape Hessian evaluated at critical shapes are analysed. First, it is proved that the stability cannot be expected for the model problem. Then, the new estimates for the shape Hessian are derived in order to overcome the classical two norms-discrepancy well know in control problems, Malanowski (2001). In the context of shape optimization, the situation is similar compared to control problems, actually, the shape Hessian can be coercive only in the norm strictly weaker with respect to the norm of the second order differentiability of the shape functional. In addition, it is shown that an appropriate regularization makes possible the stability of critical shapes.
Źródło:
Control and Cybernetics; 2003, 32, 3; 503-528
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pre-shape calculus and its application to mesh quality optimization
Autorzy:
Luft, Daniel
Schulz, Volker
Powiązania:
https://bibliotekanauki.pl/articles/2183466.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape optimization
mesh quality
mesh deformation method
shape calculus
Opis:
Deformations of the computational mesh, arising from optimization routines, usually lead to decrease of mesh quality or even destruction of the mesh. We propose a theoretical framework using pre-shapes to generalize the classical shape optimization and calculus. We define pre-shape derivatives and derive corresponding structure and calculus theorems. In particular, tangential directions are featured in pre-shape derivatives, in contrast to classical shape derivatives, featuring only normal directions. Techniques from classical shape optimization and calculus are shown to carry over to this framework. An optimization problem class for mesh quality is introduced, which is solvable with the use of pre-shape derivatives. This class allows for simultaneous optimization of the classical shape objectives and mesh quality without deteriorating the classical shape optimization solution. The new techniques are implemented and numerically tested for 2D and 3D.
Źródło:
Control and Cybernetics; 2021, 50, 3; 263--301
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape derivatives for general objective functions and the incompressible Navier-Stokes equations
Autorzy:
Schmidt, S.
Schulz, V.
Powiązania:
https://bibliotekanauki.pl/articles/969869.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape optimization
shape derivative
Navier-Stokes
adjoint calculus
Opis:
The aim of this paper is to present the shape derivative for a wide array of objective functions using the incompressible Navier-Stokes equations as a state constraint. Most real world applications of computational fluid dynamics are shape optimization problems in nature, yet special shape optimization techniques are seldom used outside the field of elliptic partial differential equations and linear elasticity. This article tries to be self contained, also presenting many useful results from the literature. We conclude with a comparison of different objective functions for the shape optimization of an obstacle in a channel, which can be done quite conveniently when one knows the general form of the shape gradient.
Źródło:
Control and Cybernetics; 2010, 39, 3; 677-713
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic programming approach to shape optimization
Autorzy:
Fulmański, P.
Nowakowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/206302.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
dynamic programming
shape optimization
Opis:
We provide a dynamic programming approach through the level set setting to structural optimization problems. By constructing a dual dynamic programming method we provide the verification theorem for optimal and "−optimal solutions of shape optimization problem.
Źródło:
Control and Cybernetics; 2014, 43, 3; 379-401
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On shape sensitivity analysis of the cost functional without shape sensitivity of the state variable
Autorzy:
Kasumba, H.
Kunisch, K.
Powiązania:
https://bibliotekanauki.pl/articles/206115.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape derivative
Navier-Stokes equations
cost functional
Opis:
A general framework for calculating shape derivatives for domain optimization problems with partial differential equations as constraints is presented. The first order approximation of the cost with respect to the geometry perturbation is arranged in an efficient manner that allows the computation of the shape derivative of the cost without the necessity to involve the shape derivative of the state variable. In doing so, the state variable is only required to be Lipschitz continuous with respect to geometry perturbations. Application to shape optimization with the Navier-Stokes equations as PDE constraint is given.
Źródło:
Control and Cybernetics; 2011, 40, 4; 989-1017
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape sensitivity analysis of time-dependent flows of incompressible non-Newtonian fluids
Autorzy:
Sokołowski, J.
Stebel, J.
Powiązania:
https://bibliotekanauki.pl/articles/206105.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
shape optimization
shape gradient
incompressible viscous fluid
Navier-Stokes equations
Opis:
We study the shape differentiability of a cost function for the flow of an incompressible viscous fluid of power-law type. The fluid is confined to a bounded planar domain surrounding an obstacle. For smooth perturbations of the shape of the obstacle we express the shape gradient of the cost function which can be subsequently used to improve the initial design.
Źródło:
Control and Cybernetics; 2011, 40, 4; 1077-1097
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shape optimization of the modular press body
Autorzy:
Pabiszczak, S.
Powiązania:
https://bibliotekanauki.pl/articles/94162.pdf
Data publikacji:
2016
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
shape optimization
construction of machine body
Opis:
A paper contains an optimization algorithm of cross-sectional dimensions of a modular press body for the minimum mass criterion. Parameters of the wall thickness and the angle of their inclination relative to the base of section are assumed as the decision variables. The overall dimensions are treated as a constant. The optimal values of parameters were calculated using numerical method of the tool Solver in the program Microsoft Excel. The results of the optimization procedure helped reduce body weight by 27% while maintaining the required rigidity of the body.
Źródło:
Archives of Mechanical Technology and Materials; 2016, 36; 59-64
2450-9469
Pojawia się w:
Archives of Mechanical Technology and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intelligent Machining of Shape Memory Alloys
Autorzy:
Gupta, Kapil
Powiązania:
https://bibliotekanauki.pl/articles/2123283.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
WEDM
optimization
shape memory alloy
TOPSIS-Fuzzy
Opis:
Shape memory alloys are important biomaterials but difficult-to-machine (DTM). Their machining needs to be done using intelligent techniques to obtain a better machinability. Hybrid optimization is one of such techniques which can do modelling and optimization of machining parameters for the best values of machinability indicators. Wire electric discharge machining (WEDM) of shape memory alloy has been found as a prominent alternate to the conventional machining techniques, however it needs the assistance of intelligent techniques to machine such materials to get the optimum values of machinability indicators. In this paper, WEDM of shape memory alloy Ni55.8Ti is reported. WEDM has been done by varying four process parameters i.e. servo voltage SV, pulse-on time Pon, pulse-off time Poff, and wire feed rate WF using Taguchi L16 robust design of experiment technique. A hybrid optimization technique TOPSIS-Fuzzy-PSO has been successfully used to optimize these parameters (SV-50V; Pon-1µs; Poff-17 µs; WF-4 m/min) for the best possible values of material removal rate (MRR)- 0.049 g/min, maximum roughness- 11.45 µm, and recast layer- 22.10 µm simultaneously.
Źródło:
Advances in Science and Technology. Research Journal; 2021, 15, 3; 43--53
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 1394

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