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RISS 인기검색어
- 검색키워드
- 저자 : Keisuke Kubota (검색결과 3 건)
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Comparison of VRFT, NCbT and VRFT with Spline Fitting
Keisuke Kubota,Nobuhiko Koyama,Ichiro Kitamuki,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
In order to design an optimal controller for a feedback system with an unknown plant, it is a common way to identify the plant by performing plural experiments. On the contrary, certain methods used to design a controller using the data from one-time experiments have been proposed. Such methods include Virtual Reference Feedback Tuning (VRFT) and Noniterative Correlation-based Tuning (NCbT). These methods are expected to reduce the design cost. However, VRFT cannot be used to design an optimal controller from a data with noise and NCbT is limited in that there is no correlation of a reference signal with noise. An actual plant often has higher harmonics of an input signal as noise. Such noises are correlated with a reference signal. Therefore, a controller design must be able to deal with various kinds of noises. This paper proposes a method of applying spline fitting to VRFT. To verify the effectiveness of this technique, we compared the response of the proposed method with that of VRFT and NCbT on a simulator. Then, we designed each controller using VRFT, NCbT, and VRFT+SF, respectively, by providing white Gaussian noise and periodic noise. As a result, this paper shows that the proposed method surpasses the original VRFT and NCbT based on overall experimental results.
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Nobuhiko Koyama,Keisuke Kubota,Ichiro Kitamuki,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
Several methods have been proposed for designing a controller using experimental data directly without identifying a controlled plant. Among them, optimal controller design methods from one-time experimental data, such as Virtual Reference Feedback Tuning (VRFT), Fictitious Reference Iterative Tuning (FRIT), and Noniterative Correlation-based Tuning (NCbT), are especially expected to reduce the time and cost of designing a controller. VRFT and FRIT make a reference signal from experimental data. In contrast, NCbT is a method that removes noise influence by determining parameters for the controller so as not to have the interrelation of the correlation function between a reference signal and noise. However, VRFT and FRIT cannot deal with data that include noises. Although NCbT can be used to design an optimal controller from experimental data with noise, it is limited to cases where there is no interrelation between a reference signal and noise. In this paper, we show a summary of the conventional method and argue about a problem where there is noise. We also propose a data conversion method using linearity after applying spline fitting instead of using experimental data directly. In addition, we discuss the advantages of the conventional method and the proposed method.
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Iwata, Hisato,Yamaguchi, Keisuke,Takeshita, Yoko,Kubota, Akira,Hirakawa, Shusaku,Isobe, Tomohiko,Hirano, Masashi,Kim, Eun-Young Elsevier 2015 Aquatic toxicology Vol.162 No.-
<P><B>Abstract</B></P> <P>This study aimed to elucidate the catalytic function of cytochrome P450 (CYP) 1 enzymes in aquatic mammals. Alkoxyresorufin <I>O</I>-dealkylation (AROD) activities including methoxy- (MROD), ethoxy- (EROD), pentoxy- (PROD), and benzyloxyresorufin <I>O</I>-dealkylation (BROD), and 2- and 4-hydroxylation activities of 17β-estradiol (E<SUB>2</SUB>) were measured by using yeast-expressed Baikal seal (<I>Pusa sibirica</I>) CYP1A1, 1A2, and 1B1 proteins. Heterologous protein expression of the Baikal seal CYP1s (bsCYP1s) in yeast microsomes was confirmed by reduced CO-difference spectra and immunoblotting. Heterologously expressed human CYP1 enzyme (hCYP1) activities were simultaneously measured and compared with those of bsCYP1 isozymes. Recombinant bsCYP1A1 protein showed the highest <I>V</I> <SUB>max</SUB> of EROD, followed by MROD, PROD, and BROD, similar to that of hCYP1A1. <I>V</I> <SUB>max</SUB>/<I>K</I> <SUB>m</SUB> ratios of all AROD activities catalyzed by bsCYP1A1 were lower than those catalyzed by hCYP1A1, suggesting less potential for AROD by bsCYP1A1. Enzymatic assays for bsCYP1A2 showed no or minimal AROD activities, while hCYP1A2 displayed MROD and EROD activities. bsCYP1B1 showed an AROD profile (EROD>BROD>MROD>>PROD) similar to that of hCYP1B1; however, <I>V</I> <SUB>max</SUB>/<I>K</I> <SUB>m</SUB> ratios of all AROD activities by bsCYP1B1 were higher. Yeast microsomes containing bsCYP1A1 and 1B1 and hCYP1A1, 1A2, and 1B1 metabolized E<SUB>2</SUB> to 2-OHE<SUB>2</SUB> and 4-OHE<SUB>2</SUB>, whereas bsCYP1A2 showed no such activity. Comparison of 4- and 2-hydroxylations of E<SUB>2</SUB> by CYP1As suggests that bsCYP1A1, hCYP1A1, and 1A2 preferentially catalyze 2- rather than 4-hydroxylation. As for CYP1B1, the <I>V</I> <SUB>max</SUB>/<I>K</I> <SUB>m</SUB> ratios suggest that both Baikal seal and human CYPs catalyze 4- rather than 2-hydroxylation. Interspecies comparison showed that bsCYP1B1 has higher metabolic potencies for both E<SUB>2</SUB> hydroxylations than does hCYP1B1, whereas the activity of bsCYP1A1 was lower than that of hCYP1A1. Messenger RNA expression levels of bsCYP1s in the liver of Baikal seals indicated that bsCYP1A1 and 1A2 enzymes contributed to 16.2% and 83.7% of total CYP1s, respectively; bsCYP1B1 accounted for only 0.06%. Addition of anti-human CYP1A1 antibody in seal liver microsomes suppressed EROD activity more than did anti-human CYP1A2 antibody. Therefore, EROD may be catalyzed by hepatic bsCYP1A1 but not bsCYP1A2, consistent with the results of yeast-expressed bsCYP1A1 and 1A2. <I>In silico</I> substrate-docking models of bsCYP1s suggested that the defect in bsCYP1A2 enzymatic activities may be accounted for by the Pro substitution of highly conserved Thr in the I-helix, which is involved in formation of a hydrogen bond with the hydroperoxy intermediate on the heme. This Thr-Pro substitution is evolutionarily conserved across aquatic mammals and could explain their lower metabolic potential for persistent organic pollutants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Catalytic activities of Baikal seal CYP1A1 were lower than those of human CYP1A1. </LI> <LI> Baikal seal CYP1B1 showed higher catalytic activities than human CYP1B1. </LI> <LI> Catalytic activities by Baikal seal CYP1A2 showed no or a minimal detectable value. </LI> <LI> Pro317 substitution appears to render seal CYP1A2 incapable of its catalytic function. </LI> <LI> This substitution is evolutionarily conserved in aquatic mammals. </LI> </UL> </P>
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