• 제목/요약/키워드: Quasi-dimensional

검색결과 418건 처리시간 0.025초

자동미분법과 Broyden 혼합법을 이용한 2차원 원통형상에서의 경계온도 역추정 (Inverse Boundary Temperature Estimation in a Two-Dimensional Cylindrical Enclosure Using Automatic Differentiation and Broyden Combined Method)

  • 김기완;김동민;백승욱
    • 대한기계학회논문집B
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    • 제30권3호
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    • pp.270-277
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    • 2006
  • Inverse radiation problems were solved for estimating boundary temperature distribution in a way of function estimation approach in an axisymmetric absorbing, emitting and scattering medium, given the measured radiative data. In order to reduce the computational time fur the calculation of sensitivity matrix, automatic differentiation and Broyden combined method were adopted, and their computational precision and efficiency were compared with the result obtained by finite difference approximation.. In inverse analysis, the effects of the precision of sensitivity matrix, the number of measurement points and measurement error on the estimation accuracy had been inspected using quasi-Newton method as an inverse method. Inverse solutions were validated with the result acquired by additional inverse methods of conjugate-gradient method or Levenberg-Marquardt method.

PLANK PROBLEMS, POLARIZATION AND CHEBYSHEV CONSTANTS

  • Revesz, Szilard-Gy.;Sarantopoulos, Yannis
    • 대한수학회지
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    • 제41권1호
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    • pp.157-174
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    • 2004
  • In this work we discuss "plank problems" for complex Banach spaces and in particular for the classical $L^{p}(\mu)$ spaces. In the case $1\;{\leq}\;p\;{\leq}\;2$ we obtain optimal results and for finite dimensional complex Banach spaces, in a special case, we have improved an early result by K. Ball [3]. By using these results, in some cases we are able to find best possible lower bounds for the norms of homogeneous polynomials which are products of linear forms. In particular, we give an estimate in the case of a real Hilbert space which seems to be a difficult problem. We have also obtained some results on the so-called n-th (linear) polarization constant of a Banach space which is an isometric property of the space. Finally, known polynomial inequalities have been derived as simple consequences of various results related to plank problems.

Bending response of functionally graded piezoelectric plates using a two-variable shear deformation theory

  • Zenkour, Ashraf M.;Hafed, Zahra S.
    • Advances in aircraft and spacecraft science
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    • 제7권2호
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    • pp.115-134
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    • 2020
  • This paper proposes a bending analysis for a functionally graded piezoelectric (FGP) plate through utilizing a two-variable shear deformation plate theory under simply-supported edge conditions. The number of unknown functions used in this theory is only four. The electric potential distribution is assumed to be a combination of a cosine function along the cartesian coordinate. Applying the analytical solutions of FGP plate by using Navier's approach and the principle of virtual work, the equilibrium equations are derived. The paper also discusses thoroughly the impact of applied electric voltage, plate's aspect ratio, thickness ratio and inhomogeneity parameter. Results are compared with the analytical solution obtained by classical plate theory, first-order-shear deformation theory, higher-order shear deformation plate theories and quasi-three-dimensional sinusoidal shear deformation plate theory.

Theoretical and experimental modal responses of adhesive bonded T-joints

  • Kunche, Mani Chandra;Mishra, Pradeep K.;Nallala, Hari Babu;Hirwani, Chetan K.;Katariya, Pankaj V.;Panda, Subhransu;Panda, Subrata K.
    • Wind and Structures
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    • 제29권5호
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    • pp.361-369
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    • 2019
  • The modal frequency responses of adhesive bonded T-joint structure have been analyzed numerically and verified with own experimental data. For this purpose, the damped free frequencies of the bonded joint have been computed using a three-dimensional finite element model via ANSYS parametric design language (APDL) code. The practical relevance of the joint structure analysis has been established by comparing the simulation data with the in-house experimental values. Additionally, the influences of various geometrical and material parameters on the damped free frequency responses of the joint structure have been investigated and final inferences discussed in details. It is observed that the natural frequency values increase for the higher aspect ratios of the joint structure. Also, the joint made up of Glass fiber/epoxy with quasi-isotropic fiber orientation indicates more resistance towards free vibration.

이중연소 램제트엔진의 성능해석 기법 (Performance Analysis Method for Dual Combustion Ramjet Engines)

  • 서봉균;염효원;성홍계;길현용;윤현걸
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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    • pp.326-330
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    • 2011
  • 이중연소 램제트엔진의 아음속 연소기의 연소가스와 스크램제트 모드로 흡입되는 흡입공기의 혼합 및 초음속 연소를 고려한 이중연소램제트 성능해석 기법을 개발하고 검증하였다. 극초음속 흡입구의 유동특성을 고려하기 위하여 Taylor-Maccoll 방정식을 사용하였으며 초음속 연소기 해석을 위해 준 1차원 연소모델 및 CEA를 이용한 화학 평형 모델을 적용하였다. 개발된 모델을 통하여 계산된 흡입구와 연소기에서의 열역학 데이터를 수치해석 결과와 비교하였다.

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Proposed approach for determination of tributary areas for scattered pressure taps

  • Aly, Aly Mousaad
    • Wind and Structures
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    • 제16권6호
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    • pp.617-627
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    • 2013
  • In wind load calculations based on pressure measurements, the concept of 'tributary area' is usually used. The literature has less guidance for a systematic computational methodology for calculating tributary areas, in general, and for scattered pressure taps, in particular. To the best of the author's knowledge, there is no generic mathematical equation that helps calculate the tributary areas for irregular pressure taps. Traditionally, the drawing of tributary boundaries for scattered and intensively distributed taps may not be feasible (a time and resource consuming task). To alleviate this problem, this paper presents a proposed numerical approach for tributary area calculations on rectangular surfaces. The approach makes use of the available coordinates of the pressure taps and the dimensions of the surface. The proposed technique is illustrated by two application examples: first, quasi-regularly distributed pressure taps, and second, taps that have scattered distribution on a rectangular surface. The accuracy and the efficacy of the approach are assessed, and a comparison with a traditional method is presented.

STUDY OF MAGNETISM IN THE LAYERED TRANSITION METAL COMPOUND ${(C_{n}H_{2n+1}NH_{3})}_{2}CuCl_{4}\;(n=10,\;14)$

  • Lee, C.H.;Lee, K.W.;Lee, Cheol-Eui;Kang, J.K.
    • 한국자기학회지
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    • 제5권5호
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    • pp.358-361
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    • 1995
  • We have investigated the quasi-two-dimensional magnetism for the layered transition metal compound (C/sub n/H/sub 2n+1/NH/sub 3/)/sub 2/CuCl/sub 4/ (n=10, 14) in the high temperature regions by means of EPR (Electron Paramagnetic Resonance) and SQUID measurements. As a result, the magnetic transitions were reflected in the EPR linewidths and the magnetic suceptibilities in a sensitive manner. Fluctuations of the magnetic susceptibility and a similar variation of the .DELTA. g =(g/sub .parallel. -/g/sub .perp. /)g/sub .parallel. / value were also observed around the structural phase transition temperatures.

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Lateral performance of CRCS connections with tube plate

  • Jafari, Rahman;Attari, Nader K.A.;Nikkhoo, Ali;Alizadeh, Saeid
    • Steel and Composite Structures
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    • 제32권1호
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    • pp.37-57
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    • 2019
  • This paper presents experimental and analytical studies to evaluate the cyclic behaviour of Circular Reinforced Concrete column Steel beam (CRCS) connections. Two 3/4-scale CRCS specimens are tested under quasi-static reversed cyclic loading. Specimens were strengthened with a tube plate (TP) and a steel doubler plate (SDP). Furthermore; nine interior beam-through type RCS connections are simulated using nonlinear three-dimensional finite element method using ABAQUS software and are verified with experimental results. The results revealed that using the TP improves the performance of the panel zone by providing better confinement to the concrete. Utilizing the TP at the panel zone may absorb and distribute stress in this region. Results demonstrate that TP can be used instead of SDP. Test records indicate that specimens with TP, with and without SDP maintained their maximum strength up to 4% drift angle, satisfying the recommendation given by AISC341-2016 for composite special moment-resisting frames.

Thermocline 축열조 측벽에서의 열전도 해석 (Analytical Solution of Two -dimensional Conduction in the Side Wall of a Thermocline System Enclosure)

  • 이준식
    • 대한설비공학회지:설비저널
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    • 제16권1호
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    • pp.103-108
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    • 1987
  • The heat transfer processes taking place in the side wall of a thermocline enclosure have been analyzed for idealized conditions based on the assumption that, at any instant time, side wall heat transfer processses are independent of the thermocline bulk motion. However, the axial tempera-ture distribution in the thermocline core provides the means for specifying the liquid medium-side boundary condition to the enclosure side wall. A picture is drawn which reflects the side wan response to thermocline bulk motion within the frame work of a quasi-steady analytic approach. For valves of the parameters typical of systems of engineering interest, the analysis shows that a significant amount of heat transfer short - circuiting can take place along the side wall enclosure. This phenomenon is favored by high values of $H_l$ and low values of P and $H_g$ respec-tively. The location of the point of zero normal heat flux on the side wan can be expected to mark, approximately, the region of confluence of two sidewall boundary flows respectively driven by the buoyant effects.

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Terahertz emission from a plasma dipole oscillation

  • Min Sup Hur;Manoj Kumar;Hyung Seon Song;Teyoun Kang
    • Journal of the Korean Physical Society
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    • 제80권
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    • pp.852-858
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    • 2022
  • We studied an unrevealed characteristic of radiation emission from a localized plasma oscillator (plasma dipole oscillation-PDO). PDO is a novel concept of generating terahertz emission from a laser plasma-based system. The electromagnetic field generated by a PDO embedded in a uniform plasma, instead of being cut off by the ambient plasma as expected by a common but misleading sense, propagates long distances to escape the plasma eventually. The PDO-THz, differently from other laser plasma-based THz sources, utilizes the collective behavior of the plasma (plasma oscillations) and, accordingly, produces a quasi-narrow-band emission, which can potentially be useful in THz-based accelerator or THz-pump and probe experiments. We verified the PDO mechanism by using realistic three-dimensional particle-in-cell simulations.