• 제목/요약/키워드: Derivative analysis

검색결과 830건 처리시간 0.28초

Sensitivity analysis for optimal design of piezoelectric structures (압전지능구조물의 최적설계를 위한 민감도 해석)

  • 김재환
    • Journal of KSNVE
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    • 제8권2호
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    • pp.267-273
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    • 1998
  • This study aims at performing sensitivity analysis of piezoelectric smart structure for minimizing radiated noise from the structure, The structure consists of a flat plate on which disk shaped piezoelectric actuator is mounted, and finite element modeling is used for the structure. The finite element modeling uses a combination of three dimensional piezoelectric, flat shell and transition elements so thus it can take into account the coupling effects of the piezoelectric device precisely and it can also reduce the degrees of freedom of the finite element model. Electric potential on the piezoelectric actuator is taken as a design variable and total radiated power of the structure is chosen as an objective function. The objective function can be represented as Rayleigh's integral equation and is a function of normal displacements of the structure. For the convenience of computation, all degrees of freedom of the finite element equation is condensed out except the normal displacements of the structure. To perform the design sensitivity analysis, the derivative of the objective function with respect to the normal displacements is found, and the derivative of the norma displacements with respect to the design variable is calculated from the finite element equation by using so called the adjoint variable method. The analysis results are compared with those of the finite difference method, and shows a good agreement. This sensitivity analysis is faster and more accurate than the finite difference method. Once the sensitivity analysis program is used for gradient-based optimizations, one could achieve a better convergence rate than non-derivative methods for optimal design of piezoelectric smart structures.

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A Simulation for the Second Derivative of a Mean Busy Cycle in a Markov Renewal Process (마코르 리뉴얼 과정에서 평균 busy cycle의 2계도함수에 대한 시뮬레이션)

  • 박흥식
    • Proceedings of the Korea Society for Simulation Conference
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    • 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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    • pp.294-298
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    • 1999
  • In this paper, through simulations, we find the second derivative SPA(Smoothed Perturbation Analysis) estimates of mean busy cycle with respect to a given parameter in a Markov renewal process which is generated by two exponential distributions. We compare these SPA estimates with the traditional SD(symetric difference) estimates.

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Quantitative analysis by derivative spectrophotometry (ll) Derivative spectrophotometry and methods for the reduction of high frequency noises

  • Park, Man-Ki;Cho, Jung-Hwan
    • Archives of Pharmacal Research
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    • 제10권1호
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    • pp.1-8
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    • 1987
  • One of the problems of derivatie spectrophotometry, the decrease of signal-to-noise ratio by derivative operations, was solved by three concepts of digital filtering, ensemble averaging, least squares polynomial smoothing and Fourier smoothing. The suthors made several compouter programs written in APPLE SOFT BASIC language for the actual applications of the concepts of these digital filters on UV spectrophotometer system. As a result, ensemble averaging could not be used as a routine operation for the spectrophotometer used. The maximum S/N ratio enhancement factors achieved by least squares polynomial smoothing were 6.17 and 7.47 for the spectra of Gaussian and Lorentzian distribution models, and by Fourier smoothing 16.42 and 11.78 for the spectra of two models, respectively.

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Study on Electrochemical Sensing Property of Harbor Pollutants using Viologen Derivative (Viologen 유도체를 이용한 항만오염물질의 전기화학적 센싱 특성 연구)

  • Park, Sang-Hyun;Lee, Dong-Yun;Kwon, Young-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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    • pp.119-120
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    • 2008
  • In this paper, viologen derivative is used as charge transfer material to develop sensors for detecting the organic pollutants which are the main reason of harbor pollution. We fabricated self-assembled monolayers of viologen derivative on gold electrode of QCM and investigated an electrochemical behavior property. We also determined electrochemical sensing property about environmental pollution materials such as bezene, phosphate and surfactant through quantitative and qualitative analysis of charge transfer using intrinsic property of viologen derivative by temperature and concentration change. From the achieved results, we can apply and develope the detecting sensors for harbor pollutants.

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Analysis of Hematoporphyrin Derivative by Design and Manufacture of High Resolution Charge Coupled Device in Spectrometry (분광기에 고 분해능 Charge Coupled Device의 설계 및 제작에 의한 Hematoporphyrin Derivative의 분석)

  • Kim, Ki-Jun
    • Journal of the Korean Applied Science and Technology
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    • 제22권1호
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    • pp.77-83
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    • 2005
  • The influence of fluorescence, scattering, and absorbance in turbid material by light scattering was interpreted by the scattered fluorescence intensity and wavelength. The effect of optical property in scattering media was investigated. It is very important to study the charge coupled device(CCD) in spectrometry because we can use the molecular energy level, molecular structure, absorption or emission, intermolecular reaction, weakly bound molecular energy, photochemistry, fluorescence and photodynamic therapy. CCD is very essential to study the molecular structure and medical engineering combined laser spectroscopy in the modem physical and chemistry. Accordingly, this study has designed and manufactured the electromagnetic spectrometry with CCD, and has analyzed the hematoporphyrin derivative.

Proportional and Derivative Control of Hydrodynamic Journal Bearings (동압 베어링의 비례 및 미분 제어)

  • 노병후;김경웅
    • Tribology and Lubricants
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    • 제17권4호
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    • pp.283-289
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    • 2001
  • The paper presents the stability characteristics of a rotor-bearing system supported by actively controlled hydrodynamic journal bearing. The proportional and derivative controls including coupled motion are adopted for the control algorithm to control the hydrodynamic journal bearing with a circumferentially groove. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than a conventional analysis which uses the Reynolds condition. The stability characteristics of a rotor-bearing system supported by actively controlled hydrodynamic journal bearing are investigated for various control gains with the Routh-Hurwitz criteria using the linear dynamic coefficients which are obtained from the perturbation method. It is found that the speed at onset of the instability is increased for both proportional and derivative control of the bearing. It is also found that the proportional and derivative control of the coupled motion is more effective than that of the uncoupled motion.

SOME INEQUALITIES ON POLAR DERIVATIVE OF A POLYNOMIAL

  • Devi, Khangembam Babina;Krishnadas, Kshetrimayum;Chanam, Barchand
    • Nonlinear Functional Analysis and Applications
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    • 제27권1호
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    • pp.141-148
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    • 2022
  • Let p(z) be a polynomial of degree n having no zero in |z| < k, k ≤ 1, then Govil proved $$\max_{{\mid}z{\mid}=1}{\mid}p^{\prime}(z){\mid}{\leq}{\frac{n}{1+k^n}}\max_{{\mid}z{\mid}=1}{\mid}p(z){\mid}$$, provided |p'(z)| and |q'(z)| attain their maximal at the same point on the circle |z| = 1, where $$q(z)=z^n{\overline{p(\frac{1}{\overline{z}})}}$$. In this paper, we extend the above inequality to polar derivative of a polynomial. Further, we also prove an improved version of above inequality into polar derivative.

TURÁN-TYPE Lr-INEQUALITIES FOR POLAR DERIVATIVE OF A POLYNOMIAL

  • Robinson Soraisam;Mayanglambam Singhajit Singh;Barchand Chanam
    • Nonlinear Functional Analysis and Applications
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    • 제28권3호
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    • pp.731-751
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    • 2023
  • If p(z) is a polynomial of degree n having all its zeros in |z| ≤ k, k ≥ 1, then for any complex number α with |α| ≥ k, and r ≥ 1, Aziz [1] proved $$\left{{\int}_{0}^{2{\pi}}\,{\left|1+k^ne^{i{\theta}}\right|^r}\,d{\theta}\right}^{\frac{1}{r}}\;{\max\limits_{{\mid}z{\mid}=1}}\,{\mid}p^{\prime}(z){\mid}\,{\geq}\,n\,\left{{\int}_{0}^{2{\pi}}\,{\left|p(e^{i{\theta}})\right|^r\,d{\theta}\right}^{\frac{1}{r}}.$$ In this paper, we obtain an improved extension of the above inequality into polar derivative. Further, we also extend an inequality on polar derivative recently proved by Rather et al. [20] into Lr-norm. Our results not only extend some known polynomial inequalities, but also reduce to some interesting results as particular cases.

Lr INEQUALITIES FOR POLYNOMIALS

  • Reingachan N;Mayanglambam Singhajit Singh;Nirmal Kumar Singha;Khangembam Babina Devi;Barchand Chanam
    • Nonlinear Functional Analysis and Applications
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    • 제29권2호
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    • pp.451-460
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    • 2024
  • If a0 + Σnν=μ aνzν, 1 ≤ µ ≤ n, is a polynomial of degree n having no zeroin |z| < k, k ≥ 1 and p'(z) its derivative, then Qazi [19] proved $$\max_{{\left|z\right|=1}}\left|p\prime(z)\right|\leq{n}\frac{1+\frac{{\mu}}{n}\left|\frac{a_{\mu}}{a_0} \right|k^{{\mu}+1}}{1+k^{{\mu}+1}+\frac{{\mu}}{n}\left|\frac{a_{\mu}}{a_0} \right|(k^{{\mu}+1}+k^{2{\mu}})}\max_{{\left|z\right|=1}}\left|p(z)\right|$$ In this paper, we not only obtain the Lr version of the polar derivative of the above inequality for r > 0, but also obtain an improved Lr extension in polar derivative.

Study on the Applications of Automatic Differentiation in Engineering Computation (자동 미분의 공학 계산 적용 연구)

  • Lee, Jae-Hun;Im, Dong-Kyun;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • 제36권7호
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    • pp.634-641
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    • 2008
  • Automatic Differentiation(AD) is a tool for generating sensitivities, such as gradient or Jacobian, automatically. AD tools provide mathematically exact sensitivities for the given source code. In this paper applications of automatic differentiation are studied. Derivative codes are generated with AD tools for structural analysis code and flow analysis code. How to apply AD tools is explained and the accuracy of sensitivities is compared with the finite difference. Sensitivities of generated derivative code accord well with finite difference, but the calculation time of derivative code increases. It was found that the calculation time can be decreased by additional modification of derivative code.