• Title/Summary/Keyword: Neutral Trace

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Dual-model Predictive Direct Power Control for Grid-connected Three-level Converter Systems

  • Hu, Bihua;Kang, Longyun;Feng, Teng;Wang, Shubiao;Cheng, Jiancai;Zhang, Zhi
    • Journal of Power Electronics
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    • v.18 no.5
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    • pp.1448-1457
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    • 2018
  • Many researchers devote themselves to develop model-predictive direct power control (MPDPC) so as to accelerate the response speed of the grid-connected systems, but they are troubled its large computing amount. On the basis of MPDPC, dual MPDPC (DMPDPC) is presented in this paper. The proposed algorithm divides the conventional MPDPC into two steps. In the first step, the optimal sector is obtained, which contains the optimal switching state in three-level converters. In the second step, the optimal switching state in the selected sector is searched to trace reference active and reactive power and balance neutral point voltage. Simulation and experiment results show that the proposed algorithm not only decreases the computational amount remarkably but also improves the steady-state performance. The dynamic response of the DMPDPC is as fast as that of the MPDPC.

FAR-INFRARED [C II] EMISSION FROM THE CENTRAL REGIONS OF SPIRAL GALAXIES

  • MOCHIZUKI KENJI
    • Journal of The Korean Astronomical Society
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    • v.37 no.4
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    • pp.193-197
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    • 2004
  • Anomalies in the far-infrared [C II] 158 ${\mu}m$ line emission observed in the central one-kiloparsec regions of spiral galaxies are reviewed. Low far-infrared intensity ratios of the [C II] line to the continuum were observed in the center of the Milky Way, because the heating ratio of the gas to the dust is reduced by the soft interstellar radiation field due to late-type stars in the Galactic bulge. In contrast, such low line-to-continuum ratios were not obtained in the center of the nearby spiral M31, in spite of its bright bulge. A comparison with numerical simulations showed that a typical column density of the neutral interstellar medium between illuminating sources at $hv {\~} 1 eV $ is $N_H {\le}10^{21}\;cm^{-2}$ in the region; the medium is translucent for photons sufficiently energetic to heat the grains but not sufficiently energetic to heat the gas. This interpretation is consistent with the combination of the extremely high [C Il]/CO J = 1-0 line intensity ratios and the low recent star-forming activity in the region; the neutral interstellar medium is not sufficiently opaque to protect the species even against the moderately intense incident UV radiation. The above results were unexpected from classical views of the [C II] emission, which was generally considered to trace intense interstellar UV radiation enhanced by active star formation.

Analysis of Burn-back Tendency on the Finocyl Grain (Finocyl 그레인의 Burn-back 경향성 분석)

  • Park, Chan Woo;Roh, Tae-Seong;Lee, Hyoung Jin;Jung, Eunhee
    • Journal of the Korean Society of Propulsion Engineers
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    • v.25 no.2
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    • pp.55-65
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    • 2021
  • In this study, the design criteria is presented for Finocyl grain, which is easy to generate neutral thrust when designing solid rocket motors. For this purpose, an automated program using drafting method was developed for burn-back analysis and its accuracy was validated. Using this developed program, burn-back analysis was performed with various configuration parameters of Finocyl grain, and the tendency and sensitivity analysis on burning characteristics were performed. Based on this analysis, the design criteria were presented to generate the neutral burning surface area trace for a Finocyl grain.

Studies on Change of Lipids Improvement-Meju during the Fermentation (개량(改良)메주의 숙성과정(熟成過程) 중 지질(脂質)조성의 변화(變化)에 관(關)한 연구(硏究))

  • Yang, Soo Dong;Bae, Man Jong;Yoon, Sang Hong;Choi, Cheong
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.12 no.3
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    • pp.189-195
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    • 1983
  • Changes of lipid composition in the Improvement-Meju inoculated with Aspergillus oryzae were examined. To investigate those changes systematically, silicic acid column chromatography was used for analysis of glycolipid, neutral lipid, phospholipid, and gas chromatography to examine the change of those fatty acid content. Following results were obtained. The lipid fraction obtained from soaked soybean and cooked soybean were mainly composed of about 93~94% neutral lipid, whereas phospholipid and glycolipid was 4.0~5.0%, 2.0~2.1% level, respectively. During meju incuvation period, neutral lipid decreased gradually, but glycolipid and phospholipid increased. Among the nonpolar lipids prepared from cooked soybean and soaked soybean, triglyceride content was mainly composed of 88~89%, and the content of sterol ester, free fatty acid, diglyceride and sterol was higher in soaked soybean than in cooked soybean. During meju incuvation period, triglyceride content decreased remarkablely, whereas content of sterol ester, free fatty acid and diglyceride increased gradually. From the soaked soybean and the cooked soybean, the fatty acids content of crude lipid, neutral lipid, glycolipid and phospholipid were composed of linoleic acid 54~70%, oleic acid 20.0~22.6%, palmitic acid 11.0~12.4%, linolenic acid 6.0~7.8% and stearic acid 3.4~4.3% in turn and myristic acid showed the trace, palmitic acid was a little higher in glycolipid and phospholipid than in crude lipid and neutral lipid. During meju incuvation period, the change of fatty acid content showed linoleic acid and linolenic acid reduction gradually in the neutral lipid, glycolipid and phospholipid. On the other hand, palmitic acid, stearic acid and oleic acid increased gradually, the maximum value was at the 4-days. The change of glycolipid fatty acid and phospholipid fatty acid was examined. 9-kinds including traced 3-kinds was detected. It was supposed that traced 2-kinks was occurred for incuvation, and those are the matter investigating in the future.

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Impact of Current Density, Operating Time and pH of Textile Wastewater Treatment by Electrocoagulation Process

  • Hossain, Md. Milon;Mahmud, Md. Iqbal;Parvez, Md. Shohan;Cho, Haeng Muk
    • Environmental Engineering Research
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    • v.18 no.3
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    • pp.157-161
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    • 2013
  • Treatment of textile wastewater by the electrocoagulation (EC) process is being investigated by this experimental study. The objective of this experiment is to observe the efficiency of the EC process in removing chemical oxygen demand (COD) and turbidity. In this experiment an iron electrode is used in the EC process, and different working parameters such as pH, current density and operating time were studied in an attempt to achieve a higher removal capacity. The results show that the maximum COD removal occurred at neutral pH at operating time 30 min. COD and turbidity removal reaches at maximum, with optimum consumption of electrodes, between current density 85-95 $A/m^2$, and only trace amounts of metals were determined in the EC treated effluent.

A New Grid-Based Monte Carlo Code for Raman Scattered He II: Preliminary Results

  • Chang, Seok-Jun;Choi, Bo-Eun;Lee, Hee-Won
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.85.2-85.2
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    • 2019
  • We developed a new grid-based Monte Carlo code to trace far UV He II line photons that are incident on a thick H I region and subsequently transferred through Rayleigh and Raman scattering with atomic hydrogen. In particular, we consider a neutral region that is moving away from the He II emission source which is either monochromatic or is described by a Gaussian profile. The resultant Raman scattered He II line profiles from a monochromatic source are characterized by a double peaked core part with an extended Raman red tail that is attributed to multiple re-entry events. Complicated behaviors are observed in the case of a Gaussian He II source including the formation of a secondary red peak near the Balmer center dependent on the H I column density. A preliminary application of our results to the CFHT data of the planetary nebula IC 5117 is presented.

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Chemical Composition of Rainwater in Chonju-city, Korea (전주시에서 채수된 강수의 화학적 조성)

  • 나춘기;정재일
    • Journal of Korean Society for Atmospheric Environment
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    • v.13 no.5
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    • pp.371-381
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    • 1997
  • Precipitation sampls were collected in Chonju-city during October 1994 to September 1995 and were analysed for major ions (N $a^{+}$, $K^{+}$, $Ca^{2+}$, $Mg^{2+}$, C $l^{[-10]}$ , NO/$_3$, S $O_4$$^{2-}$) and trace metals (Al, Cd, Ni, Pb, Sr, Zn) in addition to pH, in order to understand the chemical characteristics of acid rain and to estimate the origin of the determined ions. Most rain showed a neutral or alkaline character, and only 35% had a pH lower than 5.6. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ are identified as the primary contributors to precipitation acidity in this region. Neutralization of precipitation acidity occurs as a result of the dissolution of alkaline compounds containing $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ precipitation concentrations exhibit a seasonal pattern in which higher concentrations are observed during spring months and lower concentrations during summer months. However, the seasonal behavior of $H^{+}$ concentrations differs from this pattern, in that the highest concentrations occur during autumn months, owing to the different influence of neutralization processes. In all rain, S $O_4$$^{2-}$ concentration exceeded NO/$_3$$^{[-10]}$ concentration. The contribution of maritime sources to the total S $O_4$$^{2-}$ concentration was very low or negligible. For rain strongly affacted by yellow sand, $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$ ions show a sharp increase in concentration, reflecting the increased amount of dust and soil suspended in atmosphere. At the same time, S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ concentrations are at their highest levels while $H^{+}$ values are not comparably elevated, presumably beacause much of the acidity has been neutralized by alkaline substances. The seasonal variance of trace metal concentrations in rainwater is similar to that of major cations. The annual wet flux of acidic pollutants and trace metals wat calculated to be as follows: N $O_3$$^{[-10]}$ ; 2.32 g/$m^2$, S $O_4$$^{2-}$, 5.34 g/$m^2$, Al; 6.30 mg/$m^2$, Cd; 0.62 mg/$m^2$, Ni; 4.08 mg/$m^2$, Pb: 9.76 mg/$m^2$, Sr; 5.94 mg/$m^2$, Zn; 111 mg/$m^2$./$m^2$.

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A Historical Study on the Visual Inconsistency of Sexual Image in Dress (복식에서 성의 가시적 불일치에 관한 사적 연구 -고대에서 근대까지-)

  • 이민선;김민자
    • Journal of the Korean Society of Clothing and Textiles
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    • v.19 no.2
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    • pp.340-355
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    • 1995
  • purpose of this study was to trace historically the causes of the visual inconsistency of seXual ilT'age in dress with versatile perspectives. For this purpose, theoretical studies about the concepts of sexuality in dress were precceded. To trace the factors of the visual inconsistency of sexual image in dress, historical studies from ancient Egypt to modern ages were done. And then, the factors of the visual inconsist\ulcornerency of sexual image in dress were identified. The synthetic results were as follows; L The visual inconsistency of sexual image in dress shows the phenomena that men introduce the traditional feminine image in dress (ex. X silhouette, skirts), whereas women do the traditional masculine image (ex. Y silhouette, pants), which arouse androgynous image in appearance. And, it also indicates that men or women wear the dress excluded the traditional masculine image as well as the traditional feminine image, which arouse neutral image in appearance. 2. The visual inconsistency of sexual image in dress have been existed historically, from Egypt to modern ages. 3. The visual inconsistency of sexual image III dress was caus~d by various factors as follows; First, ideal beauty of the times which did not distinguish between masculinity and femininity resulted in the visual inconsistency of sexual image in dress. Second, as a means of seeking pleasure, the visual inconsistency of sexual image in dress was used. Third, as a means of expressing ideology, the visual inconsistency of sexual image in dress was selected. Forth,in religious meaning,the visual inconsistency ofl sexual image in dress was appeared. Fifth,popularization of sports and occupational role made woman adopt the masculine image in dress in view of the aspects of functionalism. Sixth,Undevelopment of taloring contributed to generate androgenous image in dress.

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Use of hybrid materials in the trace determination of As(V) from aqueous solutions: An electrochemical study

  • Tiwari, Diwakar;Jamsheera, A.;Zirlianngura, Zirlianngura;Lee, Seung Mok
    • Environmental Engineering Research
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    • v.22 no.2
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    • pp.186-192
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    • 2017
  • The carbon paste electrode (CPE) was modified with the pristine bentonite and hybrid material (HDTMA-modified bentonite). The modified-CPEs are then employed as working electrode in an electrochemical detection of As(V) from aqueous solutions using the cyclic voltammetric measurements. Cyclic voltammograms revealed that As(V) showed reversible behavior onto the working electrode. The hybrid material-modified carbon paste electrode showed significantly enhanced electrochemical signal which was then utilized in the low level detection of As(V). Moreover, the studies were conducted at neutral pH conditions. The electrochemical studies were conducted with scan rates (20 to 200 mV/s) to deduce the mechanism of redox processes involved at the electrode surface. The anodic current was linearly increased, increasing the concentration of As(V) from 5.0 to $35.0{\mu}g/g$ using the hybrid material-modified electrode. This provided fairly a good calibration line for As(V) detection. The presence of varied concentrations of As(III) in the determination of total arsenic was studied. The influence of several cations and anions viz., Cu(II), Mn(II), Zn(II), Pb(II), Cd(II), Fe(III), $Cl^-$, $NO_3{^-}$, $PO_4{^{3-}}$, EDTA and glycine in the detection of As(V) from aqueous solution was also studied. Further, in an attempt to simulate the real matrix analysis, the tap water sample was spiked with As(V) and subjected for As(V) detection using the modified-CPE.

Studies on the Lipids of 'Bugbangjohgae' Spisula sachalinensis (북방 조개의 유지에 관한 연구)

  • JOH Yong Goe;HATA Mitsuo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.9 no.3
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    • pp.195-202
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    • 1976
  • The present investigation was performed to find the lipid composition of the total lipids, the fatty acid components of the neutral lipids and the phospholipids, and the composition of sterols, from Spisula sachalinensis. The results obtained are as follows ; 1) The main components of the total lipids are phospholipids$(43.1\%)$, triglyceride$(36.2\%) $, and sterol $(10.3\%)$. 2) The phospholipids are mainly composed of phosphatidyl choline, phosphatidyl ethanols, mine, phosphatidal ethanolamine and phosphatidyl serine. 3) The main fatty acids of the neutral lipids, the ethanolamine phospholipids and choline phospholpids, are C20:5, C16:1, C16:0, C20:5, C18:0, C22:6 and C16:0, C20:5, C22:6, respectively. Oleic acid content of all fractions is very small compared with one of gastropoda lipids and fish oil. 4) Most of plasmalogen are present in the ethanolamine phospholipids and only trace of plasmalogen in the choline phospholipids. 5) Sterols to be found are 22-trans-norcholesta-5, 22-diene-$3\beta$-ol, 22-dehydrocholesterol, cholesterol, brassicasterol, 24-methylenecho-lesterol and $\beta-sitosterol$.

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