• 제목/요약/키워드: Singularities

검색결과 273건 처리시간 0.033초

CYLINDERS IN DEL PEZZO SURFACES WITH DU VAL SINGULARITIES

  • Belousov, Grigory
    • 대한수학회보
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    • 제54권5호
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    • pp.1655-1667
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    • 2017
  • We consider del Pezzo surfaces with du Val singularities. We'll prove that a del Pezzo surface X with du Val singularities has a $-K_X-polar$ cylinder if and only if there exist tiger such that the support of this tiger does not contain anti-canonical divisor. Also we classify all del Pezzo surfaces X such that X has not any cylinders.

특이성에 대한 퍼지 제어 (Fuzzy Control Through Singularity)

  • 이혜린;정정주
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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    • pp.356-356
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    • 2000
  • For irregular nonlinear systems, switching controlk form is proposed recently. This control law is designed to overcome the singularities through the scheme that switches between an approximate tracking law close to the singularities, and an exact tracking law away from the singularities. But, that form has problems which may break the system's stability through unstable control input value at switching procedure. In this paper, We propose new switching control law which supervises approximate tracking control law and exact tracking control law by fuzzy rules to overcome unstability problem in switching procedure.

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A study on Stress Singularities for V-notched Cracks in Anisotropic and/or Pseudo-isotropic Dissimilar Materials

  • Cho, Sang-Bong;Kim, Jin-kwang
    • International Journal of Precision Engineering and Manufacturing
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    • 제3권2호
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    • pp.22-32
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    • 2002
  • V-notched crack problems can be formulated as eigenvalue problems. The problem ova v-notched crack in anisotropic and/or pseudo-isotropic dissimilar materials was formulated as an eigenvalue problem to discuss stress singularities. The eigenvalue problem was served by the commercial numerical program; MATHEMATICA. The specific data of eigenvalues possessing the stress singularity were obtained. Stress singularities fur v-notched cracks in anisotropic and/or pseudo-isotropic dissimilar materials were discussed according to the relation between wedge angle and material property. It was shown that there are three cases of eigenvalues possessing the stress singularity; one real, two real and one complex.

THE SINGULARITIES FOR BIHARMONIC PROBLEM WITH CORNER SINGULARITIES

  • Woo, Gyungsoo;Kim, Seokchan
    • East Asian mathematical journal
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    • 제36권5호
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    • pp.583-591
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    • 2020
  • In [8, 9] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities. They consider the Poisson equations with corner singularities, compute the finite element solutions using standard Finite Element Methods and use the extraction formula to compute the stress intensity factor(s), then they posed new PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor(s), which converges with optimal speed. From the solution they could get an accurate solution just by adding the singular part. The error analysis was given in [5]. In their approaches, the singular functions and the extraction formula which give the stress intensity factor are the basic elements. In this paper we consider the biharmonic problems with the cramped and/or simply supported boundary conditions and get the singular functions and its duals and find properties of them, which are the cornerstones of the approaches of [8, 9, 10].

A CHARACTERIZATION OF THE VANISHING OF THE SECOND PLURIGENUS FOR NORMAL SURFACE SINGULARITIES

  • Wada, Koukichi
    • 대한수학회보
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    • 제45권2호
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    • pp.221-230
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    • 2008
  • In the study of normal (complex analytic) surface singularities, it is interesting to investigate the invariants. The purpose of this paper is to give a characterization of the vanishing of ${\delta}_2$. In [11], we gave characterizations of minimally elliptic singularities and rational triple points in terms of th.. second plurigenera ${\delta}_2$ and ${\gamma}_2$. In this paper, we also give a characterization of rational triple points in terms of a certain computation sequence. To prove our main theorems, we give two formulae for ${\delta}_2$ and ${\gamma}_2$ of rational surface singularities.

여유 자유도 매니퓰레이터를 위한 지적 제한 조건을 기반으로 한 Resolved Motion 방법의 특이점에 관한 연구 (On the Singularities of Optimality Constraint-based Resolved Motion Methods for a Redundant Manipulator)

  • 조동권;최병욱;정명진
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1992년도 하계학술대회 논문집 A
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    • pp.386-390
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    • 1992
  • Algorithmic or kinematic singularities are inevitably a introduced if optimality criteria or augmented kinematic equations are used to resolve the redundancy of almost any manipulator with rotary joints. In this paper, a sufficient condition for a singularity-free optimal solution of the kinematic control of a redundant manipulator is derived and, specifically, algorithmic singularities are analyzed for optimality-based methods. A singularity-free space (SFS) to characterize the performance of a secondary task for a redundant manipulator using the sufficient condition for a redundant manipulator is defined. The SFS is a set of regions classified by the loci of configurations satisfying the inflection condition for manipulability measure in the Configuration space. Using SFS, the topological property of the Configuration space and the invertible workspace without singularities are analyzed.

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역기구학을 이용한 케이싱 오실레이터의 자코비안 해석 (Jacobian Analysis of Casing Oscillator Using the Inverse Kinematics)

  • 배형섭;백재호;이은준;박명관
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 추계학술대회 논문집
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    • pp.576-579
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    • 2002
  • This paper presents the jacobian analysis of new type Casing Oscillator using the inverse kinematics, and to search for it's singularities through the jacobian analysis. All parallel manipulator have some singularities in workspace or it's outside workspace. Singularities were cleared by many other study of parallel manipulator f3r that reason recent publication of device control. In this paper defined that singularities of new file of Casing Oscillator and, to show it's graph. Finally this paper will be used for a practical example for construction spot, aviation simulator, vehicles simulator, military equipment etc.

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SUH35/SUH3 마찰용접 접합계면에 대한 잔류응력 특이성의 해석 (Analysis of Residual Stress Singularities on Interfaces of Friction Welded SUH35/SUH3)

  • 정남용;박철희
    • 한국자동차공학회논문집
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    • 제13권5호
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    • pp.104-111
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    • 2005
  • With increasing use of SUH35/SUH3 dissimilar materials for automotive engine valves, it is required that stress singularities under residual stress on an interface for friction welded dissimilar materials analyzed to establish strength evaluation. The stress singularity $index{\lambda}$ and stress singularities $factor{\Gamma}$ were calculated from using the results of stress analysis to consider residual stress and loads. The stress singularities on variations for shapes and thickness of welded flashes were analyzed and discussed. This paper suggested that the strength evaluation by using the stress singularity factors as fracture parameters, considering the stress singularity on an interface edge of friction welded dissimilar materials will be useful.

An assessment of non-linear elastic and elasto-plastic analyses with regards to tubular steel piles embedded in sands

  • Adolfo Foriero;Zeinab Bayati
    • Geomechanics and Engineering
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    • 제32권4호
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    • pp.397-409
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    • 2023
  • This study examines two traditional approaches (non-linear elastic and elasto-plastic) in association with 2D and 3D FEM analyses of a box-section pile embedded in sand. A particular emphasis is placed on stress singularities concerning both reentrant corners of the pile section and the resulting tension zones. From the experience gained in this study, non-linear elastic soil models are less restrictive when one considers stress singularities and their possible effects on convergence of the solution. At least for monotonic loading, when compared with field tests, non-linear elastic models yield better results than the plasticity ones. On the other hand, although elasto-plastic models are not limited to monotonic loading, they are much more sensitive to stress singularities. For this reason, a spherical elastic region is necessary at the pile tip to ensure convergence. Without this region, one must artificially impose an apparent cohesion to limit the tension stresses within a sand medium.