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Gamma分布的特征函数及点估计

定义 1 若随机变量X有概率密度函数f(x) =1Γ(α) λαxα- 1 e-λx  x 0 ( 1 )则称X服从Gamma分布 ,记作X~Γ(α ,λ) .α称为形状参数 ,λ称为尺度参数 ,且α0 ,λ0 .其中Γ( ·)是Gamma函数Γ(α) =∫∞0 tα- 1 e-tdt ( 2 )  该定义在大多数概率统计文献中都可以找到 ,其应用越来越广泛 .特别是在可靠性理论中发挥重要作用[1 ,3 ,4] .1 Gamma分布的数字特征及重要性质  由定义 1易见如下结论 :   ( 1 )当α=1时 ,Γ( 1 ,λ)就是参数为λ的指数分布 ,记为exp(λ) ;   ( 2 )当α =1为正整数时 ,Γ(n ,λ)就是Erlang分布 ,常用于可靠性理论和排队论中 ,如一个复杂系统中从第 1次故障到恰好再出现n次故障所需的时间 ;从某一艘船到达港口直到恰好有n只船到达所需的时间都服从Erlang分布 ;   ( 3)当...  (本文共5页) 阅读全文>>

《Journal of Zhejiang University Science》2001年04期
Journal of Zhejiang University Science

CONSTRUCTION AND IDENTIFICATION OF THE RECOMBINANT OF THE AAV VECTOR AND HUMAN INTERFERON-GAMMA

INTRODUCTIONAnAdeno associatedvirus(AAV)particleiscomposedofthreestructuralproteinsandalin ear ,single strandedDNA (ssDNA)genomeofapproximately 4 .7kb .AAVisadefectivehu manparvovirusthatnormallyreplicatesproduc tivelyonlyinthepresenceofhelperfunctionsprovidedbyaco infectingadenovirusorher pesvirus.AAVhasnotsofarbeenimplicatedastheetiologicagentofanydisease,andtheviralDNAintegratesintochromosome1 9atasitepre viouslyl...  (本文共3页) 阅读全文>>

《Nuclear Science and Techniques》2019年07期
Nuclear Science and Techniques

Analyzing the transient effects of ~(60)Co gamma rays in a CIS by Monte Carlo method

1 IntroductionThe CMOS image sensor (CIS)[1, 2] is an attractivedevice for use in many scientific applications, such as startracking, space remote sensing, and particle or ray trackobservation. When it is used in these harsh radiationenvironments, it can be damaged by particles or rays. Themain radiation damage effects include the total ionizingdose (TID) effects, displacement damage dose (DDD)effects, and transient ...  (本文共7页) 阅读全文>>

《中国原子能科学研究院年报》2018年00期
中国原子能科学研究院年报

Experimental Study of (197)~Au(γ,n) Photonuclear Reaction

As a standard testing experiment for photo-nuclear reaction study,the cross section of197 Au(γ,n)reaction has been investigated byusing different kinds of gamma source.Bermanetc.used positron annihilation in flight gammasource to measure the cross section of 197 Au(γ,n).Furthermore,the cross section of 197 Au(γ,n)reaction measured by bremsstrahlung gammasource was done on the facility of ELBE.Re-cently,the cross sect...  (本文共2页) 阅读全文>>

《Research in Astronomy and Astrophysics》2018年08期
Research in Astronomy and Astrophysics

Radio pulsars with expected gamma radiation and gamma-ray pulsars as pulsating radio emitters

1 INTRODUCTIONThe Fermi space telescope with the Large AreaTelescope(LAT)has detected over 150 new gamma-raypulsars,which are included in the Second Fermi LAT cat-alog(hereafter 2FGL catalog,Abdo et al.2013),increas-ing their previous number(see,for example,Thompson,1996)by a factor of several dozen.The analysis of theirproperties is very important for understanding the natureof pulsed emission.All data on gamma puls...  (本文共8页) 阅读全文>>

《临床骨科杂志》2016年06期
临床骨科杂志

闭合复位Gamma钉固定治疗老年股骨转子骨折

2010年5月~2015年12月,我科应用闭合复位Gamma钉固定治疗80例老年股骨转子骨折患者,疗效满意,报道如下。1材料与方法1.1病例资料本组80例,男24例,女56例,年龄76~95(84.23±4.28)岁。骨折按AO分型:A1型32例,A2型31例,A3型17例。受伤至手术时间2~15 d。1.2治疗方法患者腰麻后置牵引床上,透视下闭合复位。在大转子尖端上方2.0 cm处做长2.0 cm切口,于大转子尖端置入导针,透视确认位置良好后依次扩髓钉近端入口,置入Gamma钉主钉。以导向器旋入近端锁定导针,透视确认位置良好,扩近端骨皮质入口,沿导向器旋入近端钻头,确认钉长度后,旋入近端2枚6.5 mm拉力螺钉或打入1枚螺旋刀片。从导向器远端孔钻入导针,透视确认位置良好后旋入合适长度的远端锁钉。旋入尾帽。关闭切口,不置放引流。2结果患者均获得随访,时间3~24个月。骨折全部愈合,无内固定失效。1例发生远端锁钉处感染,换药、抗感...  (本文共1页) 阅读全文>>