• Title/Summary/Keyword: order parameter

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ON THE INVERSE PROBLEM FOR STURM-LIOUVILLE OPERATOR WITH A NONLINEAR SPECTRAL PARAMETER IN THE BOUNDARY CONDITION

  • Mamedov, Khanlar R.
    • Journal of the Korean Mathematical Society
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    • v.46 no.6
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    • pp.1243-1254
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    • 2009
  • The inverse scattering problem is investigated for some second order differential equation with a nonlinear spectral parameter in the boundary condition on the half line [0, $\infty$). In the present paper the coefficient of spectral parameter is not a pure imaginary number and the boundary value problem is not selfadjoint. We define the scattering data of the problem, derive the main integral equation and show that the potential is uniquely recovered.

Equivalent Physical Damping Parameter Estimation for Stable Haptic Interaction (안정적인 햅틱 상호작용을 위한 등가 물리적 댐핑 추정)

  • Kim, Jong-Phil;Seo, Chang-Hhoon;Ryu, Je-Ha
    • The Journal of Korea Robotics Society
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    • v.1 no.2
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    • pp.135-141
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    • 2006
  • This paper presents offline estimation of equivalent physical damping parameter in haptic interaction systems where damping is the most important parameter for stability. Based on the previous energy bounding algorithm, an offline procedure is developed in order to estimate the physical damping parameter of a haptic device by measuring energy flow-in to the haptic device. The proposed method does not use force/torque sensor at the handgrip. Numerical simulation and experiments verified effectiveness of the proposed method.

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Parallel Robust $H_{\infty}$ Control for Weakly Coupled Bilinear Systems with Parameter Uncertainties Using Successive Galerkin Approximation

  • Kim, Young-Joong;Lim, Myo-Taeg
    • International Journal of Control, Automation, and Systems
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    • v.4 no.6
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    • pp.689-696
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    • 2006
  • This paper presents a new algorithm for the closed-loop $H_{\infty}$ composite control of weakly coupled bilinear systems with time-varying parameter uncertainties and exogenous disturbance using the successive Galerkin approximation(SGA). By using weak coupling theory, the robust $H_{\infty}$ control can be obtained from two reduced-order robust $H_{\infty}$ control problems in parallel. The $H_{\infty}$ control theory guarantees robust closed-loop performance but the resulting problem is difficult to solve for uncertain bilinear systems. In order to overcome the difficulties inherent in the $H_{\infty}$ control problem, two $H_{\infty}$ control laws are constructed in terms of the approximated solution to two independent Hamilton-Jacobi-Isaac equations using the SGA method. One of the purposes of this paper is to design a closed-loop parallel robust $H_{\infty}$ control law for the weakly coupled bilinear systems with parameter uncertainties using the SGA method. The other is to reduce the computational complexity when the SGA method is applied to the high order systems.

Transverse Vibration of Rectangular Plates Having an Inner Cutout in Water (유공직사각형평판(有孔直四角形平板)의 접수진동(接水振動))

  • H.S.,Lee;K.C.,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.21 no.1
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    • pp.21-34
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    • 1984
  • This paper is concerned with the experimental investigation of transverse vibration characteristics in water of rectangular plates having an inner free cutout. Systematic experiments are carried out to investigate effects of the surrounding water on the added mass and the natural frequency of the plates due to the changes of the aspect ratio, hole size and eccentricity. The main subject is the clamped rectangular plate with a circular hole. For the purpose of comparative evaluations, some other common-type boundary conditions and hole shapes such as ellipses and rectangles are also investigated. Some of the results obtain are as follows; 1) For each given aspect ratio of the plate, there is a hole area ratio which gives a minimum value of the nondimensional frequency parameter for each mode. The hole area ratio increases as the order number of the mode increases. 2) The nondimensinal mass-increment parameter decreases as the aspect ration or the order number of the mode increases. For each given aspect ratio, the parameter the fundamental mode decreases monotonically as the hole area ratio increase. In cases of the second and higher order modes, however, each mode has a hole area ratio which gives a maximum value of the parameter for each aspect ratio more then 2/3. 3) Comparing elliptic holes with rectangular ones with same hole area ratio, nondimensional frequency parameters are almost same for each given ratio of the shorter axises to the longer one. 4) The influences of difference in boundary condion on nondimensional frequency parameters in water are similar to those in air.

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Elastic wave phenomenon of nanobeams including thickness stretching effect

  • Eyvazian, Arameh;Zhang, Chunwei;Musharavati, Farayi;Khan, Afrasyab;Mohamed, Abdeliazim Mustafa
    • Advances in nano research
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    • v.10 no.3
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    • pp.271-280
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    • 2021
  • The present work deals with an investigation on longitudinal wave propagation in nanobeams made of graphene sheets, for the first time. The nanobeam is modelled via a higher-order shear deformation theory accounts for both higher-order and thickness stretching terms. The general nonlocal strain gradient theory including nonlocality and strain gradient characteristics of size-dependency in order is used to examine the small-scale effects. This model has three-small scale coefficients in which two of them are for nonlocality and one of them applied for gradient effects. Hamilton supposition is applied to obtain the governing motion equation which is solved using a harmonic solution procedure. It is indicated that the longitudinal wave characteristics of the nanobeams are significantly influenced by the nonlocal parameters and strain gradient parameter. It is shown that higher nonlocal parameter is more efficient than lower nonlocal parameter to change longitudinal phase velocities, while the strain gradient parameter is the determining factor for their efficiency on the results.

Higher-order Shear Deformable Analysis of Laminated Plates on Two-parameter Elastic Foundations (Two-parameter 탄성지반위에 놓인 고차전단변형 적층판의 해석)

  • Han, Sung-Cheon;Jang, Suk-Yoon
    • Journal of Korean Society of Steel Construction
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    • v.13 no.1
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    • pp.101-113
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    • 2001
  • The main purpose of this paper is to present deflections of laminated composite plates on the two-parameter foundations. that is an elastic foundation with shear layer. This paper focuses on the deformation behaviour of anisotropic structures on elastic foundations. The third-order shear deformation theory is applied by using the double-fourier series. To validate the derived equations the obtained displacements for simply supported isotropic and orthotropic plates on elastic foundations are compared with those of Timoshenko and LUSAS program. The results show an excellent agreement for the isotropic and LUSAS program. The results show an excellent agreement for the isotropic and orthotropic plates on the elastic foundations. Numerical results for displacements are presented to show the effects of side-to-thickness ratio aspect ratio, material anisotropy and shear modulus of foundations.

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Calculation of $G_1$ for unidirectional laminated composites by using the two parameter technique (이항변수방법을 사용한 단일방향 적층복합재의 전단모드 에너지방출률 계산)

  • Rhee, Gyeong-Yeop
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.1
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    • pp.164-172
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    • 1997
  • Two parameter technique that uses far-field stress and displacement distributions was applied to composite laminates in order to calculate mode II energy release rate, $G_{II}$ . The $G_{II}$ calculated by two parameter technique was compared with that calculated from the crack closure method to inspect the effectiveness of two parameter technique. Sensitivity study of two parameter technique to the crack extension size was also performed. The results showed that both methods produced comparable $G_{II}$ results. In particular, it was found that although the crack closure method was affected by the crack extension size, the two parameter technique was less affected by the crack extension size.

Development of Fretting Fatigue Parameter (접촉피로 파라미터의 개발)

  • Lee, Hyuk-Jae
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.1
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    • pp.92-99
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    • 2011
  • In this study, new multi-axial, critical plane based, fretting fatigue crack initiation parameter is developed by the addition of a new term into the Modified Shear Stress Range(MSSR) parameter. The newly developed parameter (MSSR') is then used to evaluate fretting fatigue life of titanium alloy, Ti-6A1-4V with various contact conditions. Finite element analysis is also used in order to obtain stress distribution on the contact surface during fretting fatigue test, which is then used for the calculation of fretting fatigue parameter. The MSSR' parameter shows better performance in predicting fretting fatigue lives from the conventional fatigue data, and less scattering within fretting fatigue data with different contact geometries.

Correlation Analysis between the Rheology Parameters of Concrete and the Rheological Parameters of Wet Sieving Mortar (콘크리트 레올로지 정수와 Wet Sieving 모르타르 레올로지 정수의 상관관계 분석)

  • Kim, In-Tae;Lee, Yu-Jeong;Han, Dong-Yeop
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.103-104
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    • 2023
  • In this study, the correlation between the rheolog y parameter of fresh concrete and the rheology parameter of wet sieving mortar was analyzed for analyzing to possibility predicting the rheology parameter of fresh concrete. Through the experiment, the dynamic yield stress and plastic viscosity of concrete and wet sieving mortar show a direct proportional relationship, and the two data had a correlation. Therefore, it is thought that it is possible to predict the rheology parameter of fresh concrete through the rheology parameter of wet sieving mortar. However, in order to more accurately predict the rheology parameter of fresh concrete, it is need additional relationship analysis by collecting more rheology parameter data of fresh concrete and wet sieving mortar.

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On Practical Choice of Smoothing Parameter in Nonparametric Classification (베이즈 리스크를 이용한 커널형 분류에서 평활모수의 선택)

  • Kim, Rae-Sang;Kang, Kee-Hoon
    • Communications for Statistical Applications and Methods
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    • v.15 no.2
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    • pp.283-292
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    • 2008
  • Smoothing parameter or bandwidth plays a key role in nonparametric classification based on kernel density estimation. We consider choosing smoothing parameter in nonparametric classification, which optimize the Bayes risk. Hall and Kang (2005) clarified the theoretical properties of smoothing parameter in terms of minimizing Bayes risk and derived the optimal order of it. Bootstrap method was used in their exploring numerical properties. We compare cross-validation and bootstrap method numerically in terms of optimal order of bandwidth. Effects on misclassification rate are also examined. We confirm that bootstrap method is superior to cross-validation in both cases.