• 제목/요약/키워드: Local Polar Coordinate

검색결과 10건 처리시간 0.024초

독립좌표연성법을 이용한 원형 구멍을 갖는 단순지지 직사각형 평판의 자유진동해석 (Free Vibration Analysis of Simply-supported Rectangular Plate with a Circular Cutout by Independent Coordinate Coupling Method)

  • 곽문규;한상보
    • 한국소음진동공학회논문집
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    • 제16권6호
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    • pp.643-650
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    • 2006
  • This paper is concerned with the vibration analysis of a simply-supported rectangular plate with a circular cutout. Even though there have been many methods developed for the free vibration of the rectangular plate with a rectangular cutout, very few research has been carried out for the rectangular plate with a circular cutout. In this paper, a new methodology called independent coordinate coupling method, which was developed to save the computational effort for the free vibration analysis of rectangular plate with a rectangular cutout, is applied to the case of circular cutout. The independent coordinate coupling method employs the global coordinate system for the plate and the local coordinate system for the cutout. In the case of the rectangular plate with a circular cutout, the global coordinate system is the Cartesian coordinate system and the local coordinate system is the polar coordinate system. By imposing the compatibility condition, the relationship between the global coordinates and the local coordinates is derived. This equation is then used for the calculation of the mass and stiffness matrices resulting in eigenvalue problem. The numerical results show the efficacy of the proposed method.

독립좌표연성법을 이용한 원형 구멍을 갖는 단순지지 직사각형 평판의 자유진동해석 (Free Vibration Analysis of Simply-Supported Rectangular Plate with a Circular Cutout by Independent Coordinate Coupling Method)

  • 곽문규;한상보
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2006년도 춘계학술대회논문집
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    • pp.1177-1182
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    • 2006
  • This paper is concerned with the vibration analysis of a simply-supported rectangular plate with a circular cutout. Even though there have be en many methods developed for the free vibration of the rectangular plate with a rectangular cutout., very few research has been carried out for the rectangular plate with a circular cutout. In this paper, a new methodology called independent coordinate coupling method, which was developed to save the computational effort for the free vibration analysis of rectangular plate with a rectangular cutout, is applied to the case of circular cutout. The independent coordinate coupling method employs the global coordinate system for the plate and the local coordinate system for the cutout. In the case of the rectangular plate with a circular cutout, the global coordinate system is the Cartesian co ordinate system and the local coordinate system is the polar coordinate system. By imposing the compatibility condition, the relationship between the global coordinates and the local coordinates is derived. This equation is then used for the calculation of the mass and stiffness matrices resulting in eigenvalue problem. The numerical results show the efficacy of the proposed method.

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무차원 동영향 함수를 이용한 자유단 경계를 가진 임의 형상 평판의 진동해석 : 직선 및 곡선 경계가 혼합된 경우 (Free Vibration Analysis of Arbitrarily Shaped Plates with Free Edges Using Non-dimensional Dynamic Influence Functions: the case that straight and curved boundaries are mixed)

  • 최장훈;강상욱
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2005년도 춘계학술대회
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    • pp.534-537
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    • 2005
  • Free Vibration Analysis using Non-dimensional Dynamic Influence Function (NDIF) is extended to arbitrarily shaped plates including polygonal plates. Since the corners of polygonal plates have indefinite normal directions and additional boundary conditions related to a twisting moment at a corner along with moment and shear force zero conditions, it is not easy to apply the NDIF method to polygonal plates wi th the free boundary condition. Moreover, owing to the fact that the local polar coordinate system, which has been introduced for free plates with smoothly varying edges, cannot be employed for the straight edges of the polygonal plates, a new coordinate system is required for the polygonal plates. These problems are solved by developing the new method of modifying a corner into a circular arc and setting the normal direction at the corner to an average value of normal direct ions of two edges adjacent to the corner. Some case studies for plates with various shapes show that the proposed method gives credible natural frequencies and mode shapes for various polygons that agree well with those by an exact method or FEM (ANSYS).

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거리 형태 히스토그램을 이용한 이동로보트의 장애물 회피 주행 (Obstacle Avoidance Navigation Using Distance Profile Histogram)

  • 김현태;노흥식;조영완;박민용
    • 전자공학회논문지B
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    • 제33B권12호
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    • pp.1-12
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    • 1996
  • A new local path planning algorithm using DPH (distance profile histogram) is suggested in this paper. The proposed method makes a grid type world map using distance values from multiple ultrasonic sensors and genrates local points through which the mobile robot can avoid obstcles safely. The DPH (distance profile historgram) represents geometrical arrangement of obstacles around the robot in the local polar coordinate system which is assumed to be atached to the robot. To control robot's navigation, a three-layered control structure is adopted. The proposed local path planning algorithm is placed on the top level. And a point-to-point translation controller takes the middle level. The bottom level consists of a velcoity servo and sonar driver modules which take charge of driving physical hardwares. The validity of the propsoed method is demonstated through several experiments.

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Comparison of Image Duplication Detection Using the Polar Coordinates System and Histogram of Oriented Gradients Methods

  • Gunadi, Kartika;Adipranata, Rudy;Suryajaya, Ivan
    • Journal of information and communication convergence engineering
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    • 제17권1호
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    • pp.67-73
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    • 2019
  • In the current era of digital technology, and with the help of existing software, digital photo manipulation is becoming easier and faster. One example of this is the development of powerful image processing software that makes it easy for a digital image to be manipulated and edited. It is therefore very important to protect and maintain public trust in digital images. Several methods have been developed to detect image manipulation. In this paper, we compare two methods for detecting image duplication due to copy-move actions, namely the polar coordinate system and the histogram of oriented gradients methods. The former is a method based on the transfer of a Cartesian image to a polar form, making it easy to tell whether there are objects that have undergone a copy/move in an image, while the latter is a method for retrieving information related to the distribution, which uses a target in the local area as a tool to represent the shape of the target. We compare the accuracy, speed and memory usage of these two methods.

곡선 보의 면외 진동해석을 위한 얇은 원형 보 유한요소 (A Thin Circular Beam Finite Element for Out-of-plane Vibration Analysis of Curved Beams)

  • 김창부;김보연;송승관
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2007년도 춘계학술대회 논문집
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    • pp.1598-1606
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    • 2007
  • In this paper, we present a thin circular beam finite element for the out-of-plane vibration analysis of curved beams. The element stiffness matrix and the element mass matrix are derived respectively from the strain energy and the kinetic energy by using the natural shape functions which are obtained from an integration of the differential equations of the finite element in static equilibrium. The matrices are formulated with respect to the local polar coordinate system or to the global Cartesian coordinate system in consideration of the effects of shear deformation and rotary inertias. Some example problems are analysed. The FEM results are compared with the theoretical ones to show that the presented finite element can describe quite efficiently and accurately the out-of-plane motion of thin curved beams.

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2차원 레이저 레이진 파이더를 이용한 빠른 로컬 실내 지도 제작 (Fast Local Indoor Map Building Using a 2D Laser Range Finder)

  • 최웅;고낙용;최정상
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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    • pp.99-104
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    • 1999
  • This paper proposes an efficient method constructing a local map using the data of a scanning laser range finder. A laser range finder yields distance data of polar form, that is, distance data corresponding to every scanning directions. So, the data consists of directional angle and distance. We propose a new method to find a line fitting with a set of such data. The method uses Log-Hough Transformation. Usually, map building from these data requires some transformations between different coordinate systems. The new method alleviates such complication. Also, the method simplifies computation for line recognition and eliminates the slope quantization problems inherent in the classical Cartesian Hough transform method. To show the efficiency of the proposed method, it is applied to find a local map using the data from a laser range finder PLS(Proximity Laser Scanner, made by SICK).

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주파수 영역에서 각도 투영법을 이용한 회전 및 천이 불변 특징 추출 (Rotation and Translation Invariant Feature Extraction Using Angular Projection in Frequency Domain)

  • 이범식;김문철
    • 한국HCI학회논문지
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    • 제1권2호
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    • pp.27-33
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    • 2006
  • 본 논문은 회전 및 천이 불변 이미지 텍스처 검색의 새로운 방식을 소개한다. 주파수 영역의 극 좌표계에서 동일한 공간주파수에서 각도방향으로 투영을 함으로써 각도 투영법을 만들어 냈으며, 제안된 각도 투영법을 이용하여 주파수 영역에서 푸리에 계수의 합과 표준 편차를 특징벡터로 이용하였다. 각도 투영법을 쉽게 구현하기 위하여 극 좌표계에서 라돈변환이 수행된다. 실험 시 MPEG-7 데이터를 이용하였으며 그 결과는 여러 텍스처 이미지를 검 색하는데 있어서 특징을 잘 구별해 내는 결과를 보여준다. 또한 제안된 회전 및 천이불변 특징 추출 알고리듬은 등 방성 텍스처나 국부적인 방향성을 보이는 텍스처 영상 검색에서 효율적인 검색률을 보인다.

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A Finite Thin Circular Beam Element for In-Plane Vibration Analysis of Curved Beams

  • Kim Chang-Boo;Park Jung-Woo;Kim Sehee;Cho Chongdu
    • Journal of Mechanical Science and Technology
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    • 제19권12호
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    • pp.2187-2196
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    • 2005
  • In this paper, the stiffness and the mass matrices for the in-plane motion of a thin circular beam element are derived respectively from the strain energy and the kinetic energy by using the natural shape functions of the exact in-plane displacements which are obtained from an integration of the differential equations of a thin circular beam element in static equilibrium. The matrices are formulated in the local polar coordinate system and in the global Cartesian coordinate system with the effects of shear deformation and rotary inertia. Some numerical examples are performed to verify the element formulation and its analysis capability. The comparison of the FEM results with the theoretical ones shows that the element can describe quite efficiently and accurately the in-plane motion of thin circular beams. The stiffness and the mass matrices with respect to the coefficient vector of shape functions are presented in appendix to be utilized directly in applications without any numerical integration for their formulation.

BIFURCATIONS OF STOCHASTIC IZHIKEVICH-FITZHUGH MODEL

  • Nia, Mehdi Fatehi;Mirzavand, Elaheh
    • 호남수학학술지
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    • 제44권3호
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    • pp.402-418
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    • 2022
  • Noise is a fundamental factor to increased validity and regularity of spike propagation and neuronal firing in the nervous system. In this paper, we examine the stochastic version of the Izhikevich-FitzHugh neuron dynamical model. This approach is based on techniques presented by Luo and Guo, which provide a general framework for the bifurcation and stability analysis of two dimensional stochastic dynamical system as an Itô averaging diffusion system. By using largest lyapunov exponent, local and global stability of the stochastic system at the equilibrium point are investigated. We focus on the two kinds of stochastic bifurcations: the P-bifurcation and the D-bifurcations. By use of polar coordinate, Taylor expansion and stochastic averaging method, it is shown that there exists choices of diffusion and drift parameters such that these bifurcations occurs. Finally, numerical simulations in various viewpoints, including phase portrait, evolution in time and probability density, are presented to show the effects of the diffusion and drift coefficients that illustrate our theoretical results.