Aiming at disclosing the quantitative e ects of Coulomb forces on the ltration e ciency of aerosol particles, a three- dimensional random ber model was established to describe the microstructure of brous lters. Then, ...Aiming at disclosing the quantitative e ects of Coulomb forces on the ltration e ciency of aerosol particles, a three- dimensional random ber model was established to describe the microstructure of brous lters. Then, computational mod- els including the ow model, particle model, and electric eld model were constructed to estimate the ltration e ciency using the Fluent custom user-de ned function program, neglecting the non-uniformity of the ber potential and the particle charge distribution. The simulation results using the established models agreed with the data in the literature. In particular, the electric eld force was found to be one of the important factors required to improve the ltration e ciency estimation accuracy for the ultra ne particles. Moreover, the variation tendencies of the ltration e ciency and the pressure drop of brous lters were studied based on the in uence factors of the ber potential, particle charge-to-mass ratio, solid volume fraction, ber diameter, and face velocity. The established models and estimated results will provide important guidance on the design of high-e ciency particulate air lters for aerosol particles.展开更多
Sometimes,people with interest in measuring quality of education take intoaccountlevel in academic performance and various associated factors.Usually,an aver-age academic performance is an accustomed way of assessment...Sometimes,people with interest in measuring quality of education take intoaccountlevel in academic performance and various associated factors.Usually,an aver-age academic performance is an accustomed way of assessment;however,this studyexamines on individual basis different factors that might have an impact on the acad-emic performance of undergraduate students.Data on the semester weighted averageof class of 2012 mathematics students were acquired from the Quality Assurance andPlanning Unit and the Examination Office of the Department of Mathematics,KwameNkrumah University of Science and Technology.The main factors considered for thisresearch were entry age,gender,entry aggregate,Ghana education service gradedlevel of senior high school attended and geographical location.The statistical methodconsidered was random effect.Since the interaction or variation around the slope washighly insignificant,the random intercept model was the better alternative ahead ofthe random intercept and slope model.Statistically,not all the parameter estimatesare significant at a=0.05 level of significance.It was observed that the differencein geographical location was not significant in the main effect model.Hence where astudent comes from has no influence on their academic performance.However,entryaggregate,entry age and gender were all significant.Nevertheless,the geographical location with regard to the Northern Belt was significant in the linear trend with astandard deviation of approximately 0.712.展开更多
基金supported by the NSFC Grant(11071168)Special Funds for Doctoral Authorities of the Education Ministry(20103127110002)+2 种基金Innovation Program of Shanghai Municipal Education Commission(11zz116)EInstitutes of Shanghai Municipal Education Commission(E03004)Shanghai Leading Academic Discipline Project
基金supported by the National Key Research and Development Program (No. 2016YFC1201503)Natural Science Foundation of China (No. 21576206)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT_15R46)
文摘Aiming at disclosing the quantitative e ects of Coulomb forces on the ltration e ciency of aerosol particles, a three- dimensional random ber model was established to describe the microstructure of brous lters. Then, computational mod- els including the ow model, particle model, and electric eld model were constructed to estimate the ltration e ciency using the Fluent custom user-de ned function program, neglecting the non-uniformity of the ber potential and the particle charge distribution. The simulation results using the established models agreed with the data in the literature. In particular, the electric eld force was found to be one of the important factors required to improve the ltration e ciency estimation accuracy for the ultra ne particles. Moreover, the variation tendencies of the ltration e ciency and the pressure drop of brous lters were studied based on the in uence factors of the ber potential, particle charge-to-mass ratio, solid volume fraction, ber diameter, and face velocity. The established models and estimated results will provide important guidance on the design of high-e ciency particulate air lters for aerosol particles.
基金lt is a pleasure to thank Dr.Rev.William Obeng-Denteh,Department of Mathematics,Kwame Nkrumah University of Science and'Technology(KNUST)and also Mr.Kojo Ankar-Brewoo ofthe Quality Assurance and Planning Unit(QUAPU)for providing me with the data for my analysis.Mythanks also go to the Department of Mathematics,KNUST,for permitting me to carry out my research inthe department.I owe my deepest gratitude to my mother Miss Nancy Apagya-Bonney for supporting andfinancing me throughout my tertiary education.I thank my all Mr.Emmanuel Kwesi Sam,Aba Apagya-Bonney and family for all the kind words,finance and continuous encouragement that always pushed meto work harder.
文摘Sometimes,people with interest in measuring quality of education take intoaccountlevel in academic performance and various associated factors.Usually,an aver-age academic performance is an accustomed way of assessment;however,this studyexamines on individual basis different factors that might have an impact on the acad-emic performance of undergraduate students.Data on the semester weighted averageof class of 2012 mathematics students were acquired from the Quality Assurance andPlanning Unit and the Examination Office of the Department of Mathematics,KwameNkrumah University of Science and Technology.The main factors considered for thisresearch were entry age,gender,entry aggregate,Ghana education service gradedlevel of senior high school attended and geographical location.The statistical methodconsidered was random effect.Since the interaction or variation around the slope washighly insignificant,the random intercept model was the better alternative ahead ofthe random intercept and slope model.Statistically,not all the parameter estimatesare significant at a=0.05 level of significance.It was observed that the differencein geographical location was not significant in the main effect model.Hence where astudent comes from has no influence on their academic performance.However,entryaggregate,entry age and gender were all significant.Nevertheless,the geographical location with regard to the Northern Belt was significant in the linear trend with astandard deviation of approximately 0.712.
