• Title, Summary, Keyword: AOM parameter

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Electronic Spectroscopy and Ligand Field Analysis of trans-[CrX2([15]aneN4)]+(X=F,CI) (trans-[CrX2([15]aneN4)]+(X=F,CI)의 전자분광학과 리간드장 해석)

  • Jong-Ha Choi;In-Gyung Oh;Sang Hak Lee;Yu Chul Park
    • Journal of the Korean Chemical Society
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    • v.47 no.2
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    • pp.109-114
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    • 2003
  • The electronic absorption spectra of trans-$[CrX_2([15]aneN_4)]ClO_4\;([15]aneN_4$=1,4,8,12-tetraazacyclopentadecane; X=F, Cl) complexes have been interpreted using the ligand field theory. An AOMX program is used to optimize the differences between the calculated and the observed positions for the spin-allowed transition bands. The crystal field theory(CFT) parameter is directly related to the angular overlap model(AOM), normalized spherical harmonic hamiltonians(NSH), and semiempirical parameters. The various ligand field parameters are discussed in terms of their chemical significances. According to the ligand field analysis, we can confirm that the fluoride ligand is a very strong ${\sigma}-$ and ${\pi}-$donor while the chloride has weak ${\sigma}-$ and ${\pi}-$donor properties toward chromium(III) ion.

Spectroscopic Properties and Ligand Field Analysis of trans -Dibromo(2,2-dimethyl-1,3-diaminopropane)chromium(III) Moiety

  • Choi, Jong-Ha;Oh, In-Gyung;Lim, Woo-Taik;Ryoo, Keon-Sang;Kim, Dong-Il;Park, Yu-Chul
    • Bulletin of the Korean Chemical Society
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    • v.26 no.6
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    • pp.903-908
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    • 2005
  • The sharp-line absorption and emission spectra of $(H_{13}O_6)${$trans-[Cr(Me_2tn)_2Br_2]$}$_2Br_2(ClO_4)\;(Me_2$tn = 2,2-dimethyl-1,3-diaminopropane) have been measured between 13000 $cm^{-1}$ and 16000 $cm^{-1}$ at 5 K. The 298 K infrared and visible absorption spectra have also been measured. The nine electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using observed transitions, a ligand field analysis has been performed to probe the ligand field properties of coordinated atoms in the title chromium(III) complex ion. The zero-phonon line in the sharp-line absorption spectrum splits into two components by 286 $cm^{-1}$, and the large $^2E_g$ splitting can be reproduced by the modern ligand field theory. It is confirmed that nitrogen atoms of the Me2tn ligand have a strong $\sigma$-donor character, but the bromide has weak $\sigma$- and $\pi$-donor properties toward chromium(III) ion.

Design of Ultra-sonication Pre-Treatment System for Microalgae CELL Wall Degradation

  • Yang, Seungyoun;Mariappan, Vinayagam;Won, Dong Chan;Ann, Myungsuk;Lee, Sung Hwa
    • International journal of advanced smart convergence
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    • v.5 no.2
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    • pp.18-23
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    • 2016
  • Cell walls of microalgae consist of a polysaccharide and glycoprotein matrix providing the cells with a formidable defense against its environment. Anaerobic digestion (AD) of microalgae is primarily inhibited by the chemical composition of their cell walls containing biopolymers able to resist bacterial degradation. Adoption of pre-treatments such as thermal, thermal hydrolysis, ultrasound and enzymatic hydrolysis have the potential to remove these inhibitory compounds and enhance biogas yields by degrading the cell wall, and releasing the intracellular algogenic organic matter (AOM). This paper preproposal stage investigated the effect of different pre-treatments on microalgae cell wall, and their impact on the quantity of soluble biomass released in the media and thus on the digestion process yields. This Paper present optimum approach to degradation of the cell wall by ultra-sonication with practical design specification parameter for ultrasound based pretreatment system. As a result of this paper presents, a microalgae system in a wastewater treatment flowsheet for residual nutrient uptake can be justified by processing the waste biomass for energy recovery. As a conclusion on this result, Low energy harvesting technologies and pre-treatment of the algal biomass are required to improve the overall energy balance of this integrated system.

On the efficient buffer management and early congestion detection at a Internet gateway based on the TCP flow control mechanism (TCP 흐름제어를 이용한 인터넷 게이트웨이에서의 예측기반 버퍼관리 및 조기혼잡예측기법)

  • Yeo Jae-Yung;Choe Jin-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.1B
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    • pp.29-40
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    • 2004
  • In this paper, we propose a new early congestion detection and notification technique called QR-AQM. Unlike RED and it's variation, QR-AQM measures the total traffic rate from TCP sessions, predicts future network congestion, and determine the packet marking probability based on the measured traffic rate. By incorporating the traffic rate in the decision process of the packet marking probability, QR-AQM is capable of foreseeing future network congestion as well as terminating congestion resolution procedure in much more timely fashion than RED. As a result, simulation results show that QR-AQM maintains the buffer level within a fairly narrow range around a target buffer level that may be selected arbitrarily as a control parameter. Consequently, compared to RED and its variations, QR-AQM is expected to significantly reduce the jitter and delay variance of packets traveling through the buffer while achieving nearly identical link utilization.