• Title, Summary, Keyword: variable viscosity

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Determination of Medium Components in the Flocculating Activity and Production of Pestan Produced by Pestalotiopsis sp. by Using the Plackett-Burman Design

  • Moon, Seong-Hoon;Hong, Soon-Duck;Kwon, Gi-Seok;Suh, Hyun-Hyo;Kim, Hee-Sik;An, Keug-Hyun;Oh, Hee-Mock;Mheen, Tae-Ick;Yoon, Byung-Dae
    • Journal of Microbiology and Biotechnology
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    • v.8 no.4
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    • pp.341-346
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    • 1998
  • Optimization for the production of Pest an was followed by the Plackett-Burman Design, using modified Czapek-dox medium as the starting point. At the flask level, $K_2HPO_4$, $MgSO_4{\cdot}7H_2O$, and aeration variables positively affected the Pestan production, DCW (dry cell weight), apparent viscosity, and flocculating activity response. KCI and $FeSO_4{\cdot}7H_2O$ negatively affected the Pestan production, DCW, apparent viscosity, and flocculating activity response. Aeration variable was shown to have a positive effect on only the flocculating activity response among Pestan production, DCW, and apparent viscosity responses. In comparison of the positive and negative variables media conditions, Pestan production and flocculating activity differed by about 9 and 125 times, respectively. In particular, at the jar fermentor level, the aeration variable was the most important factor of the all responses (pestan production, DCW, apparent viscosity, flocculating activity, and anionic charge density). The flocculating activity and apparent viscosity of Pestan were closely related to the molecular chain length and charge density.

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Effect of the Velocity Suppression Techniques for a Mushy Solidification on Steady-state Mushy Region (머시응고에 대한 속도감쇠 기법이 정상상태 머시영역에 미치는 영향)

  • Kim, Woo-Seung;Kim, Deok-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.12
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    • pp.1657-1668
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    • 1998
  • In the analysis of a mushy solidification system with natural convection using a fixed grid method, the enthalpy method has been used to account for the release of latent heat. The variable viscosity, Darcy source, and hybrid methods have been employed for the velocity suppression in a mushy region. The choice of the values of solid viscosity and permeability constant in conjunction with the Darcy source term plays an important role in forming the location and shape of the phase boundaries. In this work the effects of these major parameters related to steady-state behavior in the system of mushy solidification are investigated through a simple test problem. The effective specific heat based on the spatial gradients of the enthalpy and temperature is adopted for the treatment of the release of latent heat. The effects of the Prandtl and Rayleigh numbers on the shape of mushy region are examined using the hybrid method.

Flow and Heat Transfer Analysis of Copper-water Nanofluid with Temperature Dependent Viscosity Past a Riga Plate

  • Ahmad, A.;Ahmed, S.;Abbasi, F.M.
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.181-187
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    • 2017
  • Flow of electrically conducting nanofluids is of pivotal importance in countless industrial and medical appliances. Fluctuations in thermophysical properties of such fluids due to variations in temperature have not received due attention in the available literature. Present investigation aims to fill this void by analyzing the flow of copper-water nanofluid with temperature dependent viscosity past a Riga plate. Strong wall suction and viscous dissipation have also been taken into account. Numerical solutions for the resulting nonlinear system have been obtained. Results are presented in the graphical and tabular format in order to facilitate the physical analysis. An estimated expression for skin friction coefficient and Nusselt number are obtained by performing linear regression on numerical data for embedded parameters. Results indicate that the temperature dependent viscosity alters the velocity as well as the temperature of the nanofluid and is of considerable importance in the processes where high accuracy is desired. Addition of copper nanoparticles makes the momentum boundary layer thinner whereas viscosity parameter does not affect the boundary layer thickness. Moreover, the regression expressions indicate that magnitude of rate of change in effective skin friction coefficient and Nusselt number with respect to nanoparticles volume fraction is prominent when compared with the rate of change with variable viscosity parameter and modified Hartmann number.

Research on the influence of union-pay M-payment quality and brand personality on user viscosity

  • Liu, Zi-Yang;Wang, Jun-Lin;Liu, Jiayu;Liu, Xiao-yin;Liao, Kai
    • Journal of the Korea Society of Computer and Information
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    • v.25 no.4
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    • pp.157-163
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    • 2020
  • The purpose of this study is to explore the impact of Union-Pay mobile payments on user viscosity from the perspective of service quality and brand personality. In the future, it is meaningful for CUP to obtain a stable and loyal user group in China's mobile payment market. This study uses SPSS22.0 and AMOS statistical analysis tools to conduct empirical research. In this case, this study uses mobile service quality and The brand personality is the independent variable, and the user's viscosity is the dependent variable, which studies the impact on the user's viscosity in the context of China Union-Pay mobile payment. the study. According to the analysis results, the research goal: service quality has a significant positive correlation effect on user perceived value; service quality has a significant positive correlation effect on user viscosity; perceived value has significant positive correlation effect on user viscosity; brand personality to user Viscosity has a significant positive correlation effect; brand personality has a significant positive correlation effect on user perceived value. Through this research, we can make Suggestions on the industrial development of mobile payment enterprises and provide better opinions on the development of mobile payment.

QUADRATIC B-SPLINE FINITE ELEMENT METHOD FOR THE BENJAMIN-BONA-MAHONY-BURGERS EQUATION

  • Yin, Yong-Xue;Piao, Guang-Ri
    • East Asian mathematical journal
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    • v.29 no.5
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    • pp.503-510
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    • 2013
  • A quadratic B-spline finite element method for the spatial variable combined with a Newton method for the time variable is proposed to approximate a solution of Benjamin-Bona-Mahony-Burgers (BBMB) equation. Two examples were considered to show the efficiency of the proposed scheme. The numerical solutions obtained for various viscosity were compared with the exact solutions. The numerical results show that the scheme is efficient and feasible.

Thermoviscoelastic orthotropic solid cylinder with variable thermal conductivity subjected to temperature pulse heating

  • Abouelregal, A.E.;Zenkour, A.M.
    • Earthquakes and Structures
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    • v.13 no.2
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    • pp.201-209
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    • 2017
  • This work aims to analyze the thermo-viscoelastic interaction in an orthotropic solid cylinder. The medium is considered to be variable thermal conductivity and subjected to temperature pulse. Analytical solution based on dual-phase-lags model with Voigt-type for behavior of viscoelastic material has been effectively proposed. All variables are deduced using method of Laplace transforms. Numerical results for different distribution fields, such as temperature, displacement and stress components are graphically presented. Results are discussed to illustrate the effect of variability thermal conductivity parameter as well as phase-lags and viscoelasticity on the field quantities. Results are obtained when the viscosity is ignored with and without considering variability of thermal conductivity. A comparison study is made and all results are investigated.

Micro Plishing using Electorheological fluid (ER유체를 이용한 미세 연마 가공)

  • 김욱배;이성재;박철우;이상조
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.850-853
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    • 2000
  • It is well-known that Electro-rheological(ER) fluid is a material(suspension) which shows the dramatic change of rheological properties under an electric field. Using these properties, the concept that variable apparent viscosity of ER fluid could be applicable to the polishing for micro parts was introduced. It was investigated that how it works for polishing and how it affects ER effect when abrasives were mixed with an ER fluid. Therefore a few structures for polishing using ER fluid was suggested and evaluated by means of experiments. In this paper, fundamental mechanism and experimental results are described.

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Practical Use of Self-compacting Concrete by Hydraulic Composition Containing a Segregation-Reducing Agent (수경성 물질용 분리저감제를 사용한 무다짐 콘크리트 실용화 연구)

  • 손유신;이승훈;김규동;김경태
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.275-280
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    • 2001
  • Recently, self-compacting concrete is applied in order to achieve workability improvement and rationalization in construction. But self-compacting concrete using viscosity agent has a difficulty in practical use because viscosity agent is invested small quantity and by man-power. Therefore in this paper we have been focused on the development and practical use of self-compacting concrete by hydraulic composition containing the segregation-reducing agent. According to mix variable, we find out right quantity of water, binder and rate of admixture replacement, and also we find out the optimum mix proportion. In the result, self-compacting concrete by hydraulic composition containing the segregation reducing agent gave satisfaction with standard and its demand will increase in the future.

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Development of High Viscosity Pulping Method for Korean Paper (I) - Atmospheric Pressure Pulping Characteristics of Paper Mulberry White Bast - (고점도 펄프를 위한 새로운 한지 펄프화법의 개발(제1보) - 닥나무 백피의 상압 펄프화 특성 -)

  • Lee, Sang-Hyun;Choi, Tae-Ho
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.43 no.2
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    • pp.57-65
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    • 2011
  • Pulping of paper mulberry (Broussonetia kazinoki) white bast has been examined by novel atmospheric pressure pulping methods. The viscosity of pulp has been found to be highly sensitive and variable with pulping methods. Therefore, selections of pulping chemicals and conditions are very important. Two kinds of pulping procedures were employed for the high viscosity pulp manufacturing. The one is ammonium oxalate treatment and the other is sodium chlorite and acetic acid treatment. Not only chemical components and pulp yields which of paper mulberry white bast but also water retention value (WRV), whiteness index, yellowness index, and colors of every pulp were examined. The hot water, 1% NaOH, and ethanol-benzene extractives which of paper mulberry white bast were 4.48%, 28.45%, and 2.84%, respectively. The contents of holocellulose, lignin, and ash were 90.66%, 1.05%, and 2.18%, respectively. In the pulp yields, group 1 which treated with only ammonium oxalate were 77.04-81.71%, group 2 which treated with ammonium oxalate and acidified sodium chlorite separately and washed between first and second stages were 64.15-83.90%, group 3 which treated with ammonium oxalate and acidified sodium chlorite separately and not washed between first and second stages were 57.35-73.17%, and group 4 which treated with mixed ammonium oxalate and acidified sodium chlorite were 66.58-68.43%. The pulps treated with acidified sodium chlorite showed high whiteness index, but the pulps treated with only ammonium oxalate showed high yellowness index. Variations in the combinations of treatments resulted in different pulp characteristics.

EFFECTS OF PHASE-LAGS AND VARIABLE THERMAL CONDUCTIVITY IN A THERMOVISCOELASTIC SOLID WITH A CYLINDRICAL CAVITY

  • Zenkour, Ashraf M.
    • Honam Mathematical Journal
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    • v.38 no.3
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    • pp.435-454
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    • 2016
  • This paper investigates the effect of dual-phase-lags on a thermoviscoelastic orthotropic solid with a cylindrical cavity. The cylindrical cavity is subjected to a thermal shock varying heat and its material is taken to be of Kelvin-Voigt type. The phase-lag thermoelastic model, Lord and Shulman's model and the coupled thermoelasticity model are employed to study the thermomechanical coupling, thermal and mechanical relaxation (viscous) effects. Numerical solutions for temperature, displacement and thermal stresses are obtained by using the method of Laplace transforms. Numerical results are plotted to illustrate the effect phase-lags, viscoelasticity, and the variability thermal conductivity parameter on the studied fields. The variations of all field quantities in the context of dual-phase-lags and coupled thermoelasticity models follow similar trends while the Lord and Shulman's model may be different. The influence of viscosity parameter and variability of thermal conductivity is very pronounced on temperature and thermal stresses of the thermoviscoelastic solids.