Based on the analysis of heat transfer mechanics,physical and chemical change of pellet drying and preheating process in grate,the mathematical model is established and solved by three-diagonal matrix algorithm. With ...Based on the analysis of heat transfer mechanics,physical and chemical change of pellet drying and preheating process in grate,the mathematical model is established and solved by three-diagonal matrix algorithm. With Visual Basic 6.0 a simulation software is developed.The model is verified by measurements at a domestic pellet plant,and the temperature distribution of pellet bed is gained.Meanwhile,the influence of different operation parameters on the pellet thermal process is studied.The results can be taken as a basis of practical production control and the grate optimizing design.展开更多
The study of the propagation of infectious diseases in urban centers finds a close connection with their population's social characteristics and behavior.This work performs a spatial analysis of dengue cases in ur...The study of the propagation of infectious diseases in urban centers finds a close connection with their population's social characteristics and behavior.This work performs a spatial analysis of dengue cases in urban centers based on the basic reproduction numbers,R0,and incidence by planning areas(PAs),as well as their correlations with the Human Development Index(HDI)and the number of trips.We analyzed dengue epidemics in 2002 at two Brazilian urban centers,Belo Horizonte(BH)and Rio de Janeiro(RJ),using PAs as spatial units.Our results reveal heterogeneous spatial scenarios for both cities,with very weak correlations between R0 and both the number of trips and the HDI;in BH,the values of R0 show a less spatial heterogeneous pattern than in RJ.For BH,there are moderate correlations between incidence and both the number of trips and the HDI;meanwhile,they weakly correlate for RJ.Finally,the absence of strong correlations between the considered measures indicates that the transmission process should be treated considering the city as a whole.展开更多
Objective To review the transmission models of tuberculosis in heterogeneous population. Data sources The data used in this review were adopted mainly from the studies of models of tuberculosis reported from 1995 to 2...Objective To review the transmission models of tuberculosis in heterogeneous population. Data sources The data used in this review were adopted mainly from the studies of models of tuberculosis reported from 1995 to 2006. Study selection Relevant literature on transmission models of tuberculosis in heterogeneous populations are referenced. Results Casual/random factors and genetic factors are the main reasons for epidemics of tuberculosis in recent years. Mass public transport is playing the primary role in casually close contact which can facilitate the transmission of tuberculosis. Genetic susceptibility not only varies endemic prevalence levels, but also drastically alters the effects of treatment for tuberculosis patients. Detailed studies further exhibit that casual contact and genetic factor are responsible for over 30%-40% of the total new cases in recent years. The prevalence of tuberculosis could double （from 33% to 60%） if a genetically susceptible phenotype is present in only 30% of the population. And some challenges have emerged along with these exciting results. Conclusions Casual/random contact, public transport and genetic susceptibility are responsible for most new tuberculosis cases and a wide variation in endemic tuberculosis levels between regions. Hence, the transmission model of tuberculosis in a heterogeneous population can provide more clues to underlying mechanism of tuberculosis transmission than in a homogeneous population. However, many challenges remain for us in understanding transmission of disease.展开更多
基金the National High Technology Research and Development Program(863) of China (No.2007AA05Z215)
文摘Based on the analysis of heat transfer mechanics,physical and chemical change of pellet drying and preheating process in grate,the mathematical model is established and solved by three-diagonal matrix algorithm. With Visual Basic 6.0 a simulation software is developed.The model is verified by measurements at a domestic pellet plant,and the temperature distribution of pellet bed is gained.Meanwhile,the influence of different operation parameters on the pellet thermal process is studied.The results can be taken as a basis of practical production control and the grate optimizing design.
基金support of the National Council of Technological and Scientific Development,CNPq,Brazil(grant no.305941/2021-6)support of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior/Programa de Excelência Acadêmica(CAPES/PROEX)for the publication charge.
文摘The study of the propagation of infectious diseases in urban centers finds a close connection with their population's social characteristics and behavior.This work performs a spatial analysis of dengue cases in urban centers based on the basic reproduction numbers,R0,and incidence by planning areas(PAs),as well as their correlations with the Human Development Index(HDI)and the number of trips.We analyzed dengue epidemics in 2002 at two Brazilian urban centers,Belo Horizonte(BH)and Rio de Janeiro(RJ),using PAs as spatial units.Our results reveal heterogeneous spatial scenarios for both cities,with very weak correlations between R0 and both the number of trips and the HDI;in BH,the values of R0 show a less spatial heterogeneous pattern than in RJ.For BH,there are moderate correlations between incidence and both the number of trips and the HDI;meanwhile,they weakly correlate for RJ.Finally,the absence of strong correlations between the considered measures indicates that the transmission process should be treated considering the city as a whole.
基金the National Natural Science Foundation of China(No.30590374)the 6th Framework Programme(No.sp22-ct-2004-003824)
文摘Objective To review the transmission models of tuberculosis in heterogeneous population. Data sources The data used in this review were adopted mainly from the studies of models of tuberculosis reported from 1995 to 2006. Study selection Relevant literature on transmission models of tuberculosis in heterogeneous populations are referenced. Results Casual/random factors and genetic factors are the main reasons for epidemics of tuberculosis in recent years. Mass public transport is playing the primary role in casually close contact which can facilitate the transmission of tuberculosis. Genetic susceptibility not only varies endemic prevalence levels, but also drastically alters the effects of treatment for tuberculosis patients. Detailed studies further exhibit that casual contact and genetic factor are responsible for over 30%-40% of the total new cases in recent years. The prevalence of tuberculosis could double （from 33% to 60%） if a genetically susceptible phenotype is present in only 30% of the population. And some challenges have emerged along with these exciting results. Conclusions Casual/random contact, public transport and genetic susceptibility are responsible for most new tuberculosis cases and a wide variation in endemic tuberculosis levels between regions. Hence, the transmission model of tuberculosis in a heterogeneous population can provide more clues to underlying mechanism of tuberculosis transmission than in a homogeneous population. However, many challenges remain for us in understanding transmission of disease.
