• Nonlinear Functional Analysis and Applications
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• 제28권1호
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• pp.11-36
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• 2023

In this presentation, the particles at the matter surface (metal, crystal, nano) will be considered as the control target outside the physical domain. As is well known that control problems of quantum particles at surface had been investigated in various aspects in last couple of years, but the realization of control would become rather difficult than theoretical results. Especially, whether surface control would be valid? what kind of particles at what kind of matter surfaces can be controlled? so many questions still left as the mystery in the current research literature and papers. It means that the direct control sometime does not easy. On the other hands, control outside the physical domain is quite a interest consideration in mathematics, physics and chemistry. The main plan is to take the quantum systems operator (such as Laplacian ∆) in the form of fractional operator (∆^s , 0 < s < 1), then to consider the control outside of physical domain. Fortunately, there are many published articles in the field of applied mathematics can be referred for the achievement of control outside of domain. The external quantum control would be a fresh concept to do the physical control, first in the theoretic, second in the computational, final in the experimental issues.

• Advances in nano research
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• 제14권2호
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• pp.141-154
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• 2023

Effects of viscoelastic foundation on vibration of curved-beam structure with clamped and simply-supported boundary conditions is investigated in this study. In doing so, a micro-scale laminate composite beam with two piezoelectric face layer with a carbon nanotube reinforces composite core is considered. The whole beam structure is laid on a viscoelastic substrate which normally occurred in actual conditions. Due to small scale of the structure non-classical elasticity theory provided more accurate results. Therefore, nonlocal strain gradient theory is employed here to capture both nano-scale effects on carbon nanotubes and microscale effects because of overall scale of the structure. Equivalent homogenous properties of the composite core is obtained using Halpin-Tsai equation. The equations of motion is derived considering energy terms of the beam and variational principle in minimizing total energy. The boundary condition is assumed to be clamped at one end and simply supported at the other end. Due to nonlinear terms in the equations of motion, semi-analytical method of general differential quadrature method is engaged to solve the equations. In addition, due to complexity in developing and solving equations of motion of arches, an artificial neural network is design and implemented to capture effects of different parameters on the inplane vibration of sandwich arches. At the end, effects of several parameters including nonlocal and gradient parameters, geometrical aspect ratios and substrate constants of the structure on the natural frequency and amplitude is derived. It is observed that increasing nonlocal and gradient parameters have contradictory effects of the amplitude and frequency of vibration of the laminate beam.

• Journal of applied mathematics & informatics
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• 제42권3호
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• pp.607-623
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• 2024

This article studies the effects of heat generation/absorption and thermal radiation on the unsteady magnetohydrodynamic (MHD) Casson fluid flow past a vertical plate through rotating porous medium with constant temperature and mass diffusion. It is assumed that the plate temperature and concentration level are raised uniformly. For finding the exact solution, a set of non-dimensional partial differential equations is solved analytically using the Laplace transform technique. The influence of various non-dimensional parameters on the velocity are discussed, including the effects of the magnetic parameter M, heat generation/absorption Q, thermal radiation parameter R, Prandtl number Pr, Schmidt number Sc, permeability of porous medium parameter, Casson fluid parameter γ, on velocity, temperature, and concentration profiles, which are discussed through several figures. It is found that velocity, temperature, and concentration profiles in the case of heat generation parameter Q, Casson fluid parameter γ, thermal Grashof number Gr, mass Grashof number Gc, Permeability Porous medium parameter K, and time t have retarding effects. It is also seen that the magnetic field M, Thermal Radiation parameter R, Prandtl field Pr, Schmidt number Sc have reverse effects on it.

• 대한전자공학회논문지TC
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• 제38권3호
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• pp.35-43
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• 2001

반사형(혹은 역방향) 결합선로에서 원하는 결합도를 가질 수 있도록 모드 특성임피던스를 합성하는 방법을 새로이 제안하였다. 결합도를 나타내는 일차 비선형 미분방정식의 해 혹은 Riccati 해가 갖는 반복되는 lobe들의 최소점, 즉 null점들을 최적 섭동시키므로서 최적 합성이 이루어진다. 이 과정을 위해 일차원 배열 안테나의 공간인자 패턴 제어를 통한 일차원 비선형 소스 분포함수 합성법을 근간으로 하였으며, 기존의 우함수형 분포함수 합성을 기함수형까지 확장 적용할 수 있는 방법을 제시하였다. 그 결과로서 도출된 모드 특성임피던스들은 연속적이고 비선형적인 프로필을 가지게 된다. 합성된 우함수형 및 기함수형 분포함수에 대응되는, 비대칭형 및 대칭형 결합기들을 비교 분석하였으며, 기존의 설계방법에 비해 일반적이고 간단함을 보였다.

• Smart Structures and Systems
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• 제33권4호
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• pp.291-300
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• 2024

Uncertainty of the model, system delay and drive dynamics can be considered as normal uncertainties, and the main source of uncertainty in the seismic control system is related to the nature of the simulated seismic error. In this case, optimizing the management strategy for one particular seismic record will not yield the best results for another. In this article, we propose a framework for online management of active structural management systems with seismic uncertainty. For this purpose, the concept of reinforcement learning is used for online optimization of active crowd management software. The controller consists of a differential controller, an unplanned gain ratio, the gain of which is enhanced using an online reinforcement learning algorithm. In addition, the proposed controller includes a dynamic status forecaster to solve the delay problem. To evaluate the performance of the proposed controllers, thousands of ground motion data sets were processed and grouped according to their spectrum using fuzzy clustering techniques with spatial hazard estimation. Finally, the controller is implemented in a laboratory scale configuration and its operation is simulated on a vibration table using cluster location and some actual seismic data. The test results show that the proposed controller effectively withstands strong seismic interference with delay. The goals of this paper are towards access to adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation, implementation of sustainable and disaster-resilient buildings, sustainable human settlement planning and manage. Simulation results is believed to achieved in the near future by the ongoing development of AI and control theory.

• 한국지반공학회논문집
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• 제27권3호
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• pp.75-83
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• 2011

일반적인 불포화지반의 거동뿐만 아니라, 열과 관련된 분야, 지반환경 분야 등 다양한 분야에서 불포화 다공질 재료의 열적-수리적-역학적으로 결합된 문제들이 대두되면서 이러한 문제들을 해석하기 위한 수치도구 개발의 필요성이 대두되고 있다. 본 논문에서는 거시적 접근법(macroscopic approach)에 근거하여 불포화지반에 대한 열-수리-역학거동의 수식화를 하였다. 흙, 물, 공기에 대한 질량보존의 법칙, 에너지 보존법칙, 그리고 하중평형 조건식으로부터 결합된(coupled) 4개의 지배방정식을 유도하였다. Galerkin 간략화와 시간적분으로부터 주 변수인 변위(u), 가스압($P_g$), 유체압($P_1$), 온도(T)를 Newton의 반복과정을 이용하여 구하는 유한요소 프로그램(FEM)을 작성하였다. 개발된 프로그램을 이용하여 다공질재료에서 2상 흐름 문제 중 일차원 배수실험(u-$P_g-P_1$), 온도 압밀(u-$P_1$-T), 그리고 지표면 온도변화에 의한 말뚝의 주변지반에 대한 영향(u-$P_1$-T)에 대하여 수치해석을 수행하고 논의하였다.

• Smart Structures and Systems
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• 제19권1호
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• pp.21-31
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• 2017

To control the stochastic vibration of a vibration-sensitive instrument supported on a beam, the beam is designed as a sandwich structure with magneto-rheological visco-elastomer (MRVE) core. The MRVE has dynamic properties such as stiffness and damping adjustable by applied magnetic fields. To achieve better vibration control effectiveness, the optimal bounded parametric control for the MRVE sandwich beam with supported mass under stochastic and deterministic support motion excitations is proposed, and the stochastic and shock vibration suppression capability of the optimally controlled beam with multi-mode coupling is studied. The dynamic behavior of MRVE core is described by the visco-elastic Kelvin-Voigt model with a controllable parameter dependent on applied magnetic fields, and the parameter is considered as an active bounded control. The partial differential equations for horizontal and vertical coupling motions of the sandwich beam are obtained and converted into the multi-mode coupling vibration equations with the bounded nonlinear parametric control according to the Galerkin method. The vibration equations and corresponding performance index construct the optimal bounded parametric control problem. Then the dynamical programming equation for the control problem is derived based on the dynamical programming principle. The optimal bounded parametric control law is obtained by solving the programming equation with the bounded control constraint. The controlled vibration responses of the MRVE sandwich beam under stochastic and shock excitations are obtained by substituting the optimal bounded control into the vibration equations and solving them. The further remarkable vibration suppression capability of the optimal bounded control compared with the passive control and the influence of the control parameters on the stochastic vibration suppression effectiveness are illustrated with numerical results. The proposed optimal bounded parametric control strategy is applicable to smart visco-elastic composite structures under deterministic and stochastic excitations for improving vibration control effectiveness.

• Korea-Australia Rheology Journal
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• 제20권2호
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• pp.59-63
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• 2008

A theoretical model was developed to describe the flow behavior of a filled polymer in the packing stage of reaction injection molding and predict the residual stress distribution of thin injection-molded parts. The model predictions were compared with experiments performed for phenol-formaldehyde resin filled with wood dust and cured by urotropine. The packing stage of reaction injection molding process presents a typical example of complex non-isothermal flow combined with chemical reaction. It is shown that the time evolution of pressure distribution along the mold cavity that determines the residual stress in the final product can be described by a single 1D partial differential equation (PDE) if the rheological behavior of reacting liquid is simplistically described by the power-law approach with some approximations made for describing cure reaction and non-isothermality. In the formulation, the dimensionless time variable is defined in such a way that it includes all necessary information on the cure reaction history. Employing the routine separation of variables made possible to obtain the analytical solution for the nonlinear PDE under specific initial condition. It is shown that direct numerical solution of the PDE exactly coincides with the analytical solution. With the use of the power-law approximation that describes highly shear thinning behavior, the theoretical calculations significantly deviate from the experimental data. Bearing in mind that in the packing stage the flow is extremely slow, we employed in our theory the Newtonian law for flow of reacting liquid and described well enough the experimental data on evolution of pressure.

• 한국컴퓨터산업학회논문지
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• 제7권4호
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• pp.427-436
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• 2006

운동하는 물체의 동특성 해석을 위한 상태 공간 모델 방식이 컴퓨터에 의한 미분방정식 해석의 수학적인 도구로서 도입되었다. 시스템 표현이 간단한 행렬 연산 형태로 이루어지므로 선형 및 비선형, 시변 및 시불변 시스템과 단변수 및 다변수 시스템 등에 대하여 통일된 방식의 모델이 사용가능하다. 그리고 이러한 상태 공간 모델을 해석하기위해서는 복잡한 벡터 연산을 하여야 하지만 패킷 소프트웨어의 특정함수를 사용하여 쉽게 해석할 수가 있다. 그러나 최근에는 상용 프로그램의 발전에 따라 동특성 해석을 위한 상태 공간 모델을 대화형 도형 처리를 하여 매우 간단하게 동특성을 시뮬레이션 할 수 있는 방법이 제공되고 있다. 본 논문은 운동하는 물체의 동특성 해석을 하는 데 교육용으로 활용할 수 있는 시뮬레이터를 개발하는 목적으로 항공기의 세로 동특성 해석을 위한 시뮬레이션을 수행하고자 하였으며 항공기 세로 안정성에 대한 과도응답 특성을 해석하는 시뮬레이터를 설계하였다.

• 한국융합학회논문지
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• 제9권6호
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• pp.53-60
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• 2018

본 논문은 듀얼 확장 칼만 필터를 기반으로 2링크 매니퓰레이터의 정밀한 제어를 위한 미지 변수 추정법을 제안한다. 2링크 매니퓰레이터 시스템은 기구학 및 동역학 방정식에 비선형성을 가지며 내부 파라미터의 변화에 민감한 특성을 보인다. 이러한 시스템의 경우 내부 미지 파라미터의 추정이 매우 중요하다. 특히 거친 환경에서 작업을 수행함에 있어서 중량과 관성행렬의 변화는 시스템을 불안정하게 만드는 요소이다. 따라서 본 논문에서 제안한 방법을 기반으로 시스템의 상태 및 미지 변수를 동시에 추정하여 앞서 소개한 문제점들을 해결하고자 한다. 제안한 방법은 Mathwork에서 제공하는 Matlab 기반으로 시뮬레이션을 수행했고, 그 결과는 RLS 알고리즘과 비교하여 성능을 분석하였다. 제안된 방법은 상태 및 미지 변수 추정에 RLS 방법보다 뛰어난 추정 성능을 보임을 확인 하였다.