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Drag reduction in flow: Review of applications, mechanism and prediction
Witold Brostow 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.4
Drag reduction (DR) agents are used at very low concentrations to accelerate significantly the flow in oil pipeline conduits, oil well operations, flood water disposal, fire fighting, field irrigation, transport of suspensions and slurries, sewer systems, water heating and cooling systems, airplane tank filling, marine systems, and biomedical systems including blood flow. DR agents are typically high molecular mass polymers; this review discusses a mechanism explaining how DR occurs using such agents. All pertinent experimental findings are challenged with that mechanism and all are shown to support it. In industrial applications DR agents undergo mechanical degradation in turbulent flow. An equation predicting the degradation as a function of time is presented and successfully confronted with experimental data. Experimental methods of determination of DR are outlined. Finally a connection between DR and flocculation is discussed.
Ahmet Beycioğlu,Adil Gültekin,Hüseyin Yilmaz Aruntaş,Osman Gencel,Magdalena Dobiszewska,Witold Brostow 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.2
This study aimed to develop a Rule Based Mamdani Type Fuzzy Logic (RBMFL) model to predict the flexural strengths and compressive strengths of blended cements under elevated temperatures. Clinoptilolite was used as cement substitution material in the experimental stage. Substitution ratios in the cement mortar mix designs were selected as 0% (reference), 5%, 10%, 15% and 20%. The data used in the modeling process were obtained experimentally, after mortar specimens having reached the age of 90 days and exposed to 300C, 400C, 500C temperatures for 3 hours. In the RBMFL model, temperature (C) and substitution ratio of clinoptilolite (%) were inputs while the compressive strengths and flexural strengths of mortars were outputs. Results were compared by using some statistical methods. Statistical comparison results showed that rule based Mamdani type fuzzy logic can be an alternative approach for the evaluation of the mechanical properties of concrete under elevated temperature.
Synthesis and Characterization of Poly(ethynyldimethylsilane-co-dimethylsiloxanes). Ⅱ.
( Choi Hae-kyun ),( Baek Jong-bum ),( Seo Kwan-ho ),( P. R. Jones ),( W. Brostow ) 한국공업화학회 1992 한국공업화학회 연구논문 초록집 Vol.1992 No.0
Silicone polymers have been known for their exceptional ability to exhibit and retain superior chemical properties over a broad temperature range. The main interests in these materials stems from the fact that they can be possessd unique properties such as good low-temperature flexibility, chemical inertness and water repellency etc. Poly(ethynyldialkylsilanes) can be considered as siloxane analogs having lone pair electrons on oxygen have been replaced by the C≡C linkage having two π electron pairs. We were able to prepare as the alkynyl analogs of -[Si(CH<sub>3</sub>)<sub>2</sub>O]<sub>n</sub>-, n=1, 2, 3, …, and -[Si(CH<sub>3</sub>)<sub>2</sub>C≡C]<sub>m</sub>-, m=2, 3, 4, …, which they are stable, separable compounds. As a result that poly(ethynyldialkylsilanes) were very rigid and high crystalline materials and siloxane were known as a very flexible substances. Therefore, the polymer having various thermal properties can be got from these synthesized monomers by combination of m and n. In this study, we synthesized the ethynyldimethylsilanes winch have various unit lengths from the digrignard ethyne and diohlorodimethylsilane in THF as a solvent. Then we prepared the poly(ethynyldimethylsilane-co-dimethylsiloxanes), -[{Si(CH<sub>3</sub>)<sub>2</sub>C≡C}<sub>m+1</sub>-{Si(CH<sub>3</sub>)<sub>2</sub>O}<sub>1</sub>]<sub>n</sub>-, from various ethynyldimethylsiloxanes and dichlorotetramethylsiloxane by using the grignard reaction or Cul catalyst. These polymers were identified by IR and NMR. Their molecular weights and molecular weight distributions were measured by GPC. Their thermal properties were investigated by DSC and TGA.