低轨卫星移动通信系统中译码前传协作策略的性能研究-信号处理.PDF

CHINESE GEOGRAPHICAL SCIENCE Volum e15,Number 3,pp. !#!$ ,2005 SciencePress,Beijing,China !#$%# $’()*+ ,-#./0! +.1 $*0.1! )2 +/0%./ %. 3-%.+ 1 1 1 1 1 2 W ANG W u-yi,ZHANG Li,LIHai-rong ,LIRi-bang ,YANG Lin-sheng ,LIAO Yong-feng (! #$%’() *+ ,)*-./0 1’2 32’)$2)% /$4 5/(./6 7)%*(.2)% 7)%)/.218 91’$)%) :2/4); *+ 32’)$2)%8 =)’ ’$- !??!?!8 @ 7 91’$/A B 5/’*$/6 9)$.) *+ C’%/%). 7)4(2’*$8 D’$’%. *+ 9’E’6 :++ /’.% *+ 91’$/8 =)’ ’$- !???FG8 @ 7 91’$/ ) +4!$*#,$ :Thisstudy focuseson thedevelopm entstagesofageing and itsregionaldifferencesin Chinabased on exam ination ofofficialstatisticsand docum ents. Thedevelopm entofageing in Chinahasexperienced threem ajor stages.Firstly,in the 1950s,low coefficientofelderly population (over65 years)paced up to prim ary adulttype. Secondly,therewasa deeply drop ofthe elderlypopulation because ofnaturaldisasterand politicalfactorsin the 1960s. Thirdly, from the 1970sto the end of20th century, the constantincreasing ofelderly coefficientm ade Chinaclosetoelderlysociety.W ith statisticdataofpopulation,Logisticm odelisused to sim ulatethefuturedevelop- m entofageing,and two characteristicsofdevelopm entofageing arepresented.Firstly,asforageing from 2005 to 2050,theelderly coefficientwillgrow up significantly from 8.48% to 16.30% .Secondly,after2025,the increasing rateofelderly coefficientwillslow down gradually. Theregionaldifferencesofelderlypopulation in Chinacanbe summ arized asfollows:1)theeastern Chinapossesseshigherelderly coefficientandhugerelderpopulation than the western China; 2) about47.4% ofm unicipalitiesand provincesin the eastern China becom e elderly especially Shanghai,Zhejiang Province