• 제목/요약/키워드: complex analytical method

검색결과 431건 처리시간 0.022초

보조변수법과 복소변수를 연동한 설계 민감도 해석 연구 (Adjoint Variable Method combined with Complex Variable for Structural Design Sensitivity)

  • 김현기;조맹효
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.418-423
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    • 2008
  • Among various sensitivity evaluation techniques, semi-analytical method is quite popular since this method is more advantageous than analytical method and global finite difference method. However, SAM reveals severe inaccuracy problem when relatively large rigid body motions are identified for individual elements. Such errors result from the numerical differentiation of the pseudo load vector calculated by the finite difference scheme. In the present study, the adjoint variable method combined with complex variable is proposed to obtain the shape and size sensitivity for structural optimization. The complex variable can present accurate results regardless of the perturbation size as well as easy to be implemented. Through a few numerical examples of the static problem for the structural sensitivity, the efficiency and reliability of the adjoint variable method combined with complex variable is demonstrated.

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고시수재 의약품 중 암브록솔염산염 및 클렌부테롤염산염 함유 제제의 함량 시험법 개선 (Development of Analytical Method for Ambroxol Hydrochloride and Clenbuterol Hydrochloride Formulation in Korean Pharmaceutical Codex)

  • 이태웅;정래석;박수진;최란;심영훈;최보경;곽효선
    • 약학회지
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    • 제58권3호
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    • pp.190-199
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    • 2014
  • The Korean Pharmaceutical Codex (KPC) analytical method of ambroxol hydrochloride and clenbuterol hydrochloride formulation is complicated and needed to carry out multiple processes during the test. To improve the low efficiency of analytical procedure that makes pharmaceutical laboratory consume much time and high cost to conduct the test of this formulation, this study was performed for simplifying the pretreatment process and optimizing conditions of the HPLC assay. The analytical procedure using HPLC was developed to establish analytical specification for ambroxol hydrochloride and clenbuterol hydrochloride formulations. The newly developed analytical method has good linearity ($R^2$ >0.999), specificity, precision (RSD<1.0%) and the recovery ranges of 98.50~101.84% for ambroxol, 98.29~101.35% for clenbuterol syrup and 98.66~101.71% for clenbuterol tablets. The LOQs were 0.204 ${\mu}g/ml$ for ambroxol, 0.021 ${\mu}g/ml$ for clenbuterol syrup and 0.073 ${\mu}g/ml$ for clenbuterol tablets. The new method was performed with commercially available samples to confirm analytical conditions and validated to be suitable for saving time and cost to control the quality of routine manufactured products. This analytical method will be used for revising the monograph of ambroxol hydrochloride and clenbuterol hydrochloride formulation in next supplement of KPC.

실험실 GC-MS를 이용한 사고대비물질 분석방법 연구 (Study on the analytical method using GC-MS for the accident preparedness substances)

  • 김기준;이진선;이수영;황승률;김영희;석광설
    • 분석과학
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    • 제26권1호
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    • pp.80-85
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    • 2013
  • 본 연구는 유해화학물질관리법에 지정되어 있는 사고대비물질에 대한 실험실적 분석방법을 정립하기 위한 것으로, GC/MS 분석이 가능한 25종 사고대비물질을 대상으로 정량분석을 수행하였다. GC/MS 정량분석결과 69종 사고대비물질 중 산화프로필렌(propylene oxide) 등 21개 물질에 대한 결정계수($r^2$)는 0.998 이상을 보였고, 포스겐(phosgene)의 결정계수는 0.994, 노말-부틸아민(n-butyl amine) 외 1종은 0.987, 에틸렌디아민(ethylene diamine)은 0.958의 결정계수를 보였다. 동일한 GC/MS 분석 조건으로 표준물질을 분석한 결과 총 25종에 대한 검량선이 작성되었다. 현재 사고대비물질에 대한 분석 연구가 필요한 상황에서, 본 연구결과는 화학사고 사후 환경 영향 조사를 위한 정량분석에 도움이 될 것으로 판단된다.

Sensitivity analysis based on complex variables in FEM for linear structures

  • Azqandi, Mojtaba Sheikhi;Hassanzadeh, Mahdi;Arjmand, Mohammad
    • Advances in Computational Design
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    • 제4권1호
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    • pp.15-32
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    • 2019
  • One of the efficient and useful tools to achieve the optimal design of structures is employing the sensitivity analysis in the finite element model. In the numerical optimization process, often the semi-analytical method is used for estimation of derivatives of the objective function with respect to design variables. Numerical methods for calculation of sensitivities are susceptible to the step size in design parameters perturbation and this is one of the great disadvantages of these methods. This article uses complex variables method to calculate the sensitivity analysis and combine it with discrete sensitivity analysis. Finally, it provides a new method to obtain the sensitivity analysis for linear structures. The use of complex variables method for sensitivity analysis has several advantages compared to other numerical methods. Implementing the finite element to calculate first derivatives of sensitivity using this method has no complexity and only requires the change in finite element meshing in the imaginary axis. This means that the real value of coordinates does not change. Second, this method has the lower dependency on the step size. In this research, the process of sensitivity analysis calculation using a finite element model based on complex variables is explained for linear problems, and some examples that have known analytical solution are solved. Results obtained by using the presented method in comparison with exact solution and also finite difference method indicate the excellent efficiency of the proposed method, and it can predict the sustainable and accurate results with the several different step sizes, despite low dependence on step size.

Determination of Methylmercury in Biological Samples Using Dithizone Extraction Method Followed by Purge & Trap GC-MS

  • Lee, Jung-Sub;Ryu, Yoon-Jung;Park, Jae-Sung;Jeon, Sung-Hwan;Kim, Sam-Cwan;Kim, Young-Hee
    • Bulletin of the Korean Chemical Society
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    • 제28권12호
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    • pp.2293-2298
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    • 2007
  • In this study, a dithizone extraction technique involving purge & trap GC-MS was developed for the determination of methylmercury in biological samples, especially blood and fish. After alkaline digestion, methylmercury in biological samples was extracted into dithizone and back-extracted into aqueous sulfide solution. The extracted methylmercury was converted to the volatile ethyl derivative, purged and trapped onto a solid-phase collection medium, and then introduced into the GC-MS system. The determined MDLs of the established method were 0.9 ng·g?1 for biological samples and its accuracy and precision were found to be 93% and 3.8%, respectively. The method was validated by analysis of CRMs such as SRM 966, BCR 463 and IAEA 407 and all analytical results were within certified ranges with average RSDs of less than 6%. The analytical results of field-sampled fish also showed that the method can be successfully used as an alternative for commonly used distillation method followed by GC-CVAFS detection.

Free vibration analysis of uniform and stepped functionally graded circular cylindrical shells

  • Li, Haichao;Pang, Fuzhen;Du, Yuan;Gao, Cong
    • Steel and Composite Structures
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    • 제33권2호
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    • pp.163-180
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    • 2019
  • A semi analytical method is employed to analyze free vibration characteristics of uniform and stepped functionally graded circular cylindrical shells under complex boundary conditions. The analytical model is established based on multi-segment partitioning strategy and first-order shear deformation theory. The displacement functions are handled by unified Jacobi polynomials and Fourier series. In order to obtain continuous conditions and satisfy complex boundary conditions, the penalty method about spring technique is adopted. The solutions about free vibration behavior of functionally graded circular cylindrical shells were obtained by approach of Rayleigh-Ritz. To confirm the dependability and validity of present approach, numerical verifications and convergence studies are conducted on functionally graded cylindrical shells under various influencing factors such as boundaries, spring parameters et al. The present method apparently has rapid convergence ability and excellent stability, and the results of the paper are closely agreed with those obtained by FEM and published literatures.

The Short Time Spectra Analysis System Using The Complex LMS Algorithm and It's Applications

  • Umemoto, Toshitaka;Fujisawa, Shoichiro;Yoshida, Takeo
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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    • pp.58-63
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    • 1998
  • B.Widrow established fundamental relations between the least-mean-square (LMS) algorithm and the digital Fourier transform[1]. By extending these relations, we proposed the short time spectra analysis system using the LMS algorithm[2]. In that paper, we used the normal LMS algorithm on the thought of dealing with only real analytical signal. This algorithm minimizes the real mean-square by recursively altering the complex weight vector at each sampling instant. But, the short time spectra analysis sometimes deals with the complex signal that is outputted from complex analog filter. So, in order to optimize and develop this methods, furthermore it is necessary to derive an algorithm for the complex analytical signal. In this paper, we first discuss the new adaptive system for the spectra analysis using the complex LMS algorithm and then derive convergence condition, time constant of coefficient adjustment and frequency resolution by extending the discussion. Finally, the effectiveness of the proposed method is experimentally demonstrated by applying it to the measurement of transfer performance on complex analog filter.

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An optimized cupric reducing antioxidant capacity (CUPRAC) method for assessment of xanthine oxidase inhibition activity

  • Ahlam Majid Azeez;Mahmoud Hussain Hadwan
    • 분석과학
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    • 제36권1호
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    • pp.44-52
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    • 2023
  • This protocol clarifies a simple and precise method for measuring the activity of xanthine oxidase (XO) enzyme inhibitor. XO enzyme, which accelerates oxidative stress-related disorders through its capacity to generate hydrogen peroxide and superoxide anion radicals (O2•-), has been found to be inhibited by several plant extracts. Enzyme samples were incubated with a suitable buffer containing adequate amounts of xanthine as a substrate to determine XO activity. The method depends on direct measurements of uric acid and hydrogen peroxide production to test XO with and without interference. The CUPRAC reagent (Cu(Nc)22+) was used to inhibit enzyme reaction after incubation was complete. The generated urate and peroxide reduced the Cu(II)-neocuproine complex (Cu(Nc)22+) to a brightly colored Cu(I)-neocuproine complex (Cu(Nc)2+), which was assessed with a spectrophotometer at 450 nm. XO activity was found to be directly related to the increased absorbance of the colored Cu(I)-neocuproine complex (Cu(Nc)2+). To eliminate catalase enzyme interference, the proposed method used sodium azide and was validated against XO activity using the UV method in matched samples with t-test analysis. The proposed assay can determine XO activity with high precision, as indicated by the correlation coefficient (R2 = 0.9935) from comparison with the reference protocol.

Studies of Complex Formation between the Bromophenol Blue and some Important Aminoquinoline Antimalarials

  • Saadia-Mohamed-El-Ashry;Aly, Fatma-Ahmed;Amina-Mohamed-El-Brashy
    • Archives of Pharmacal Research
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    • 제17권6호
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    • pp.415-419
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    • 1994
  • A simple nad rapid colorimetric method for the assay of amodiaquine hydrochloride, chloroquine phosphate and primaquine phosphate is described. The method is based on the interaction of the drug base with bromophenol blue to give a ion-pair complex. The spectra of the complex shows a maxima at 415-420 nm with high apparent molar absorptivities. Beer's law was obeyed in the concentration range 1-8, 2-10 and $2-12{\;}{\mu}{\cdot}ml^{-1}$ for amodiaquine hydrochloride, primaquine phosphate and chloroquine phosphate respectively. The proposed method was applied to the determination of these drugs in certain formulations and the results were favourably comparable to the official methods.

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Effect of stacking sequence on thermal stresses in laminated plates with a quasi-square cutout using the complex variable method

  • Chaleshtari, Mohammad H. Bayati;Khoramishad, Hadi
    • Structural Engineering and Mechanics
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    • 제77권2호
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    • pp.245-259
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    • 2021
  • In this research, the influence of the laminate stacking sequence on thermal stress distribution in symmetric composite plates with a quasi-square cutout subjected to uniform heat flux is examined analytically using the complex variable technique. The analytical solution is obtained based on the thermo-elastic theory and the Lekhnitskii's method. Furthermore, by employing a suitable mapping function, the solution of symmetric laminates containing a circular cutout is extended to the quasi-square cutout. The effect of important parameters including the stacking sequence of laminates, the angular position, the bluntness, the aspect ratio of cutout, the flux angle and the composite material are examined on the thermal stress distribution. It is found out that the circular shape for cutout may not necessarily be the optimum geometry for all stacking sequences. The finite element analysis results are used to validate the analytical solution.