Combining-Randomization-and-Discrimination-for-Fin
一类离散神经系统中的混沌存在性
第50卷第2期2023年北京化工大学学报(自然科学版)Journal of Beijing University of Chemical Technology (Natural Science)Vol.50,No.22023引用格式:陈晓楠,常玉,陈娇,等.一类离散神经系统中的混沌存在性[J].北京化工大学学报(自然科学版),2023,50(2):119-125.CHEN XiaoNan,CHANG Yu,CHEN Jiao,et al.Chaos in a discrete FitzHugh -Nagumo model[J].Journal of Beijing U⁃niversity of Chemical Technology (Natural Science),2023,50(2):119-125.一类离散神经系统中的混沌存在性陈晓楠 常 玉* 陈 娇 杨睿丰(北京化工大学数理学院,北京 100029)摘 要:研究了离散FitzHugh -Nagumo 神经系统的混沌现象㊂从理论上严格证明了在一定参数条件下系统存在Marotto 意义下的混沌,并通过数值计算模拟出该混沌吸引子,以及周期14轨㊁周期16轨等其他复杂动态㊂此外,通过Lyapunov 指数的计算对Marotto 混沌吸引子的存在性加以验证㊂关键词:离散FitzHugh -Nagumo 系统;Marotto 混沌;Lyapunov 指数中图分类号:O193 DOI :10.13543/j.bhxbzr.2023.02.015收稿日期:2022-01-05基金项目:国家自然科学基金(11771033)第一作者:女,1996年生,硕士生*通信联系人E⁃mail:changyu@引 言神经系统主导着生物体生理活动的调节,其功能主要通过神经元产生㊁处理和传递电信号来实现[1-2]㊂1952年,基于乌贼巨型轴突上电位变化的实验数据,Hodgkin 等[3]建立了一个四维非线性连续数学模型 Hodgkin -Huxley 模型(HH 模型),开启了对神经元电活动的数学研究㊂随后,FitzHugh [4]在保留系统主要动态的基础上,将HH 模型简化为二维系统;之后Nagumo 等[5]通过电路实验成功实现了该模型的动态,因此该模型也被称为FitzHugh -Nagumo 模型(FHN 模型)㊂由于系统的复杂性,针对FHN 模型的动态研究一直备受关注㊂Hayashi [6]给出了FHN 模型非平凡闭轨唯一性的充分条件㊂Rocşoreanu 等[7]证明了FHN 模型中saddle⁃node 分支㊁Hopf 分支以及Bogdanov -Takens分支的存在性㊂Jing 等[8]对FHN 模型应用Euler 方法得到离散FHN 系统,证明了该系统存在周期10轨㊁倍周期级联以及混沌等复杂动态㊂之后,Zhan 等[9]推广了一类离散FHN 模型,通过数值模拟分析了系统产生混沌的内外机制,以及延滞反馈项㊁高斯白色噪声项和磁场对激发神经元放电模式的影响㊂随着对该模型研究的深入,大量结果表明模型的动态对揭示现实中神经元放电活动的机制具有重要的参考价值㊂本文以文献[9]中的离散FHN 模型为研究对象,从理论上分析了系统中Marotto 混沌的存在性,得到了这类混沌存在的参数充分条件,并通过数值模拟展示了混沌吸引子㊁高周期解等复杂的非线性动态,这些结果丰富了对该模型的研究㊂1 离散FHN 模型1.1 模型描述考虑如下离散FHN 模型[9]f :æèçöø÷x y →x +(δx -x 33-y +)I y +δτ(ax +b -y æèççççöø÷÷÷÷)(1)式中,x 表示神经元膜电位;y 表示与膜电位恢复到静息电位过程有关的恢复变量;参数I (∈R )表示神经元接受的外界刺激强度或输入电流,其他系统参数a (>0)㊁b (∈R )㊁τ(>0)㊁δ(0<δ<1)的说明参见文献[9]㊂1.2 Marotto 意义下混沌的存在性在高维离散系统中存在的最典型的混沌吸引子是Marotto 混沌,这类混沌系统的动态十分复杂,如:该系统存在任意正整数周期的周期轨;同时拥有 scrambled”集,这是一个不包括周期点㊁不可数的㊁具有初值敏感性㊁没有渐近周期点的不变集㊂此类混沌的存在性完全由系统是否拥有某类特殊不动点即snap⁃back repeller 所决定[10-11]㊂本文将从理论上研究Marotto 意义下的混沌在系统(1)中的参数存在条件㊂应用离散动力系统的定性理论可得,当b =I ,0<a <1时,系统(1)存在一个不动点Z 0(x 0,y 0)=(3(1-a ),a3(1-a )+b )㊂此不动点Z 0是snap⁃back repeller 需要满足以下条件:①存在Z 0的一个邻域U Z 0,在此邻域中Z 0是expanding 不动点,即∀Z (x ,y )∈U Z 0,Z 所有特征值的模长均大于1;②U Z 0中存在一点Z *(x *,y *)≠Z 0,满足f M (Z *)=Z 0,|D f M (Z *)|≠0,M ∈N +㊂下面讨论Z 0(x 0,y 0)是snap⁃back repeller,即满足条件①㊁②的参数充分条件㊂引理1摇若23<a <1(2)2a -13a -2<τ<12-a -22a (1-a )(3)τ(2-3a )+12(1-a )<δ<1(4)则(ⅰ)存在点集U {=(x ,y )|x (∈1+1-2aττ,1+1-δaδ-)τ,y ∈}R ,该集合中任意点的特征值都是一对共轭复数,且模长大于1;(ⅱ)存在不动点Z 0(x 0,y 0)=(3(1-a ),a3(1-a )+b )的邻域U Z 0{=(x ,y )|(x -x 0)2r 2x 0+(y -y 0)2r 2y 0≤1,r x 0,r y 0∈R }+,满足UZ 0⊂U ㊂证明:(ⅰ)首先证明2a -13a -2<12-a -22a (1-a )㊂因为23<a <1,所以2a -13a -2=3a -2+1-a 3a -2=1+1-a3a -2>1㊂由(a (1-a )-(2a -1)2a (1-a ))㊃(a (1-a )+(2a -1)2a (1-a ))=(a (1-a ))2-((2a -1)2a (1-a ))2=-9a (1-a )(a -23()a -)13<0,可得a (1-a )-(2a -1)2a (1-a )<0㊂又因为(2-a -22a (1-a ))(2-a +22a (1-a ))=(2-a )2-(22a (1-a ))2=(9a -)232>0,故2-a -22a (1-a )>0,从而有2a -13a -2-12-a -22a (1-a )=2(a (1-a )-(2a -1)2a (1-a ))(3a -2)(2-a -22a (1-a ))<0㊂其次证明1+1-δa δ-τ>1+1-2aττ>0㊂显然τ+1>2τ>2aτ,故1+1-2aττ>0㊂由式(2)以及τ>2a -13a -2,可得τ-11-a >2a -13a -2-11-a=13a -2>1㊂又由2a -13a -2>1>δ,可知τ-11-a >δ,τ>δ,从而有1+1-δaδ-τ=δ(1-a )+1-τδ-τ=(1-a ()τ-11-a-)δτ-δ>0㊂因为2a -13a -2-1a =2(a -1)2a (3a -2)>0,所以2a -13a -2>1a ㊂由τ>2a -13a -2>1a ,可得aτ>1,从而2τ1-aτ<0㊂(注意到1+1-2aτ)τ(-1+1-δa δ-)τ=(1-aτ)(2δ-2τ1-a )ττ(δ-τ)<0,故1+1-2aττ<1+1-δaδ-τ㊂又因为1-δa δ-τ<0<1+2aττ,所以1+1-δaδ-τ<1+1+2aττ㊂综上可得,点集U {=(x ,y )|x ∈㊃021㊃北京化工大学学报(自然科学版) 2023年(1+1-2aττ,1+1-δaδ-)τ,y ∈}R 是存在的㊂任取Z (x ,y )∈U ,下面证明Z (x ,y )具有一对共轭复特征值,且模长大于1㊂易知系统(1)在点Z (x ,y )处的Jacobian 矩阵为J =1+δ(1-x 2)-δδa τ1-δæèççöø÷÷τ其特征方程为λ2+p (x )λ+q (x )=0,其中p (x )=-2+δτ-δ(1-x 2),q (x )=1-δτ+δ(1-x 2)-δ2τ(1-x 2)+δ2a τ,特征值为λ1,2=-p (x )±p 2(x )-4q (x )2㊂因为x (∈1+1-2aττ,1+1-δa δ-)τ,0<δ<τ,所以p 2(x )-4q (x )=δ(2x 2(-1+1-aτ))(τx 2(-1+1+2aτ))τ<0,q (x )-1=δ(δ-τ)(τx 2(-1+1-δa δ-))τ>0,从而有点Z (x ,y )的特征值为一对共轭复数λ1,2=-p (x )2±i4q (x )-p 2(x )2,且‖λ1,2‖=q (x )>1㊂(ⅱ)为选取适当的r x 0和r y 0,先证明1+1-2aττ<3(1-a )<1+1-δaδ-τ㊂因为a <1,τ(2-3a )+12(1-a )<δ,所以τ(2-3a )+1<2δ(1-a ),从而δ-τ+1-δa <3(1-a )(δ-τ)㊂又δ<τ,故3(1-a )<1+1-δa δ-τ(5)由a >23,0<τ<12-a -22a (1-a ),可得(3a -2)τ-2aτ+1<3a -22-a -22a (1-a )-2aτ+1<3a -22-a -243×13-2aτ+1=-2-2aτ<0,从而有1+1-2aττ-3(1-a )=(3a -2)τ-2aτ+1τ<0,即1+1-2aττ<3(1-a )(6)由式(5)㊁(6)可知1+1-2aττ<3(1-a )<1+1-δa δ-τ取0<r x 0{<min 1+1-δaδ-τ-3(1-a ),3(1-a )-1+1-2aτ}τ,r y 0∈R +,考虑不动点Z 0(x 0,y 0)=(3(1-a ),a 3(1-a )+b )的邻域U Z 0{=(x ,y )|(x -x 0)2r 2x 0+(y -y 0)2r 2y 0≤}1,任取点Z (x ,y )∈U Z 0,则其横坐标x ∈[x 0-r x 0,x 0+r x 0],显然[x 0-r x 0,x 0+r x 0](⊂1+1-2aττ,1+1-δaδ-)τ,故U Z 0⊂U ㊂命题得证㊂引理2 考虑不动点Z 0(x 0,y 0)=(3(1-a ),a3(1-a )+b ),及其邻域U Z 0{=(x ,y )|(x -x 0)2r 2x 0+(y -y 0)2r 2y 0≤1,r x 0=0.1,r y 0∈R }+,若式(2)~(4),以及δ≠τ1+aτ(7)30x 0+100(δ2x 0(-33a +1+4δ+4δaτ-))δ(㊃δ2aτ(τ-δ)2)(-1+1<3003a -2+1δ+δaτ-)δ(8)成立,则在邻域U Z 0中存在一点Z *(x *,y *),满足Z *≠Z 0,f 2(Z *)=Z 0,且|D f 2(Z *)|≠0㊂证明:设有点Z *(x *,y *),令Z 1(x 1,y 1)=f (Z *),f 2(Z *)=f (Z 1)=Z 0,即x 1=x *+(δx *-(x *)33-y *+)I y 1=y *+δτ(ax *-y *+b ìîíïïïï)(9)且㊃121㊃第2期 陈晓楠等:一类离散神经系统中的混沌存在性x 1+(δx 1-x 313-y 1+)I=xy 1+δτ(ax 1-y 1+b )=y {(10)易知方程组(10)的一组解为x 1+=-x 0(+33a +1+4δ+4δa τ-)δ2y 1+=y 0-δa (x 1+-x 0)τ-{δ(11)先证(x 1+,y 1+)≠(x 0,y 0)㊂由a >23,τ>δ可(得2x 0(-33a +1+4δ+4δaτ-))(δ-2x-(33a +1+4δ+4δa τ-))δ(=37a -3+4δ+4δa τ-)δ>(37×23-3+4δ+4δa τ-)δ(=5+121δ+δaτ-)δ>0,从而x 0-x 1+=2x 0(-33a +1+4δ+4δaτ-)δ≠0(12)将式(11)代入到方程组(10)可得(x *)3-3(δ1+δ+δ2a τ-)δx*+3(δ1-δ2aτ(τ-δ))2x 1++3aτ2(τ-δ)2x 0=0(13)y *=τ(τ-δ)y 0-δaτ(x 1+-x 0)-δ(ax *+b )(τ-δ)(τ-δ)2(14)为求方程(13)在[x 0-0.1,x 0+0.1]内的解x *,令x *=s +x 0,代入方程(13)可得g (s )≡s 3+3s 2x 0+3(s x 20-1-1δ-δaτ-)δ+3δ(×δ2aτ(τ-δ)2)-1(x 0-x 1+)=0(15)下面证明方程(15)在[-0.1,0.1]内有非零解,即g (s )有非零的零点㊂令g′(s )(=3s 2+2x 0s +x 20-1-1δ-δaδ-)τ=0,可得g (s )的两个驻点s 1,2=-x 0±1+1δ+δaτ-δ,其中s 1<s 2,显然当s ∈(s 1,s 2)时,g′(s )<0㊂因为τ>δ>0,所以1+1-δa δ-τ=1+δaτ-δ-1τ-δ<1+δa τ-δ+1δ,从而有s 2=1+1δ+δa τ-δ-3(1-a )>1+1-δaδ-τ-3(1-a )>0.1,且s 1=-s 2-23(1-a )<-0.1,故[-0.1,0.1]⊂(s 1,s 2)㊂因此当s ∈[-0.1,0.1]时,g′(s )<0,即g (s )在区间[-0.1,0.1]是单调递减函数㊂由式(7)及aτ>1,有δ2aτ-(τ-δ)2=(δ(1+aτ)-τ)(δ(aτ-1)+τ)≠0(16)由式(12)㊁(16)及τ>δ>0可得g (0)=3(x 0-x 1+)(δ2aτ-(τ-δ)2)δ(τ-δ)2≠0㊂且由式(8)㊁(12)可知,g (-0.1)g (0.1)(=30(1000x 0+100(x 0-x 1+)(δδ2aτ(τ-δ)2)))-12(-1(1000(3003a -2+1δ+δaτ-)δ))-12<0,根据零点定理得,∃s *∈(-0.1,0.1),g (s *)=0,又因g (0)≠0,故s *≠0㊂综上方程(13)有实根x *=x 0+s *∈(x 0-0.1,x 0+0.1),且x *≠x 0㊂取r y 0>|y *-y 0|,从而Z *(x *,y *)∈U Z 0,Z *≠Z 0,f 2(Z *)=Z 0㊂下证|D f 2(Z *)|≠0㊂|D f (Z *)|>0|D f (Z 1)|=δ2a τ(+1-δ)τ(1+δ(1-x21+))=(-1-δ)æèççτ3δ(1-a ()3a +1+4δ+4δa τ-)δ4+3δa2+2+öø÷÷δ-2δ2a τ<0故|D f 2(Z *)|=|D f (Z 1)‖D f (Z *)|≠0㊂命题得证㊂说明:引理2中的r x 0取值为0.1,事实上只要r x 0取充分小的正数,补充形如式(8)的条件,即可得相同的结论㊂综上所述,可得如下定理㊂定理 若系统参数a ㊁τ㊁δ满足引理1与引理2中的条件,则系统(1)的不动点Z 0(x 0,y 0)=(3(1-a ),a3(1-a )+b )是snap⁃back repel⁃ler,此时系统(1)是Marotto 混沌的,即存在:1)一个正整数N ,使得对于任一整数p ≥N ,f 有㊃221㊃北京化工大学学报(自然科学版) 2023年周期p 点㊂2)一个 scrambled set”,即一个不含周期点的不可数集S 满足(a)f [S ]⊂S ;(b)对于S 中任意不相同的两点X 和Y ,有lim k →∞sup ‖f k (X )-f k (Y )‖>0;(c)对于S 中任意点X ,以及f 的任意周期点Y ,有lim k →∞sup ‖f k (X )-f k (Y )‖>0㊂3)S 有一个不可数子集S 0,对于S 0中任意点X和Y ,有lim k →∞inf ‖f k (X )-f k (Y )‖=0㊂2 数值模拟本节取两组参数,通过数值计算,对Marotto 混沌吸引子及周期轨等复杂动态进行模拟㊂1)参数组1:b =I =1,a =0.9,τ=2.47,δ=0.992㊂系统(1)存在一个不动点㊂Z 0(x 0,y 0)=(0.54772255750517,1.492950301754653),其特征值为λ1,2=1.14639±0.24135i,‖λ1,2‖>1㊂此时参数满足引理1与引理2的条件:a =0.9>23τ(2-3a )+12(1-a )=-3.645<δ<11.143=2a -13a -2<τ<12-a -22a (1-a )=3.977δ≠τ1+aτ=0.9915830x 0+100(δ2x 0(-33a +1+4δ+4δaτ-))δ(×δ2aτ(τ-δ)2)(-1+1=3.488<3003a -2+1δ+δa τ-)δ=693.637引理1中的点集U 与Z 0的邻域U Z 0分别为U {=(x ,y )|x (∈1+1-2aττ,1+1-δa δ-)τ=(0.4445,0.9631),y ∈}R U Z 0{=(x ,y )|(x -x 0)20.01+(y -y 0)24≤}1显然U Z 0⊂U ㊂∀Z (x ,y )∈U Z 0,Z (x ,y )的特征方程为λ2+p (x )λ+q (x )=0,特征值为λ1,2=-p (x )±p 2(x )-4q (x )2,‖λ1,2‖=q (x )其中p 2(x )-4q (x )<p 2(x 0-0.1)-4q (x 0-0.1)=-0.00679<0,q (x )-1>q (x 0+0.1)-1=0.44606>0,即Z 的特征值为一对模长大于1的共轭复数㊂U Z 0中存在一点Z *(x *,y *)=(0.54652802940618,-0.462001800839748),Z 1(x 1,y 1)=f (Z *)=(2.485010260145796,0.32271318340719),f 2(Z *)=Z 0,且|D f 2(Z *)|=-2.9045㊂由定理可得Z 0是一个snap⁃back repel⁃ler,即系统(1)存在Marotto 混沌吸引子㊂选取不动点Z 0(x 0,y 0)=(0.54772255750517,1.492950301754653)的邻域U Z 0中的点(0.5477,1.493)为初始点,其相图见图1,这条轨道的Lya⁃punov 指数为{-0.24197,0.07866},即为Marotto混沌吸引子㊂图1 Marotto 混沌吸引子(δ=0.992)Fig.1 A Marotto chaotic attractor(δ=0.992)不同于前一组Z 0的邻域U Z 0中r x 0(=0.1)的取值,将r x 0设置为0.08,仍能证明在一定参数条件下系统是Marotto 意义下混沌的㊂2)参数组2:b =I =1,a =0.91,τ=2.4,δ=0.99㊂系统(1)存在不动点㊂Z 0(x 0,y 0)=(0.519615242270663,1.472849870466304),其特征值为λ1,2=1.1551±0.2334i,‖λ1,2‖>1㊂存在Z 0的邻域U Z 0{=(x ,y )|(x -x 0)2r 2x 0+(y -y 0)2r 2y 0≤1,r x 0=0.08,r y 0}=2.2任取Z (x ,y )∈U Z 0,因为p 2(x )-4q (x )<p 2(x 0-㊃321㊃第2期 陈晓楠等:一类离散神经系统中的混沌存在性0.08)-4q (x 0-0.08)=-0.01955<0,q (x )-1>q (x 0+0.08)=0.33163>0,所以Z (x ,y )有一对模长大于1的共轭复特征值-p (x )±i4q (x )-p 2(x )2,且其模长q (x )>1㊂U Z 0中存在点Z *(x *,y *)=(0.45525855258397,0.664929193926399),Z 1(x 1,y 1)=f (Z *)=(2.523106596180992,0.19274677774448),f 2(Z *)=Z 0,|D f 2(Z *)|=-3.0704≠0,由条件①㊁②得,Z 0(x 0,y 0)是snap⁃back repeller,系统(1)存在Marotto 混沌吸引子,这条轨道的Lyapunov 指数为{-0.18254,0.0651}㊂针对第一组参数值,在δ=0.992时系统(1)出现了Marotto 混沌吸引子㊂本文计算了参数δ∈(0.9,1)时,以不动点Z 0邻域中的点(0.5477,1.493)为初始点的轨道的最大Lyapunov 指数,如图2所示㊂很明显,系统在δ参数区间(0.988,1)内始终保持混沌状态㊂图2 最大Lyapunov 指数图Fig.2 The maximumLyapunov exponent diagram通过数值模拟计算,我们还发现系统存在高周期轨道,如周期16轨㊁周期14轨,如图3㊁4所示㊂图3 周期16轨(δ=0.9205)Fig.3 Period⁃16orbit(δ=0.9205)图4 周期14轨(δ=0.962)Fig.4 Period⁃14orbit(δ=0.962)3 结束语本文研究了一类离散FHN 神经系统的混沌现象,主要从理论上严格证明了该系统Marotto 意义下混沌的存在性㊂此外通过数值计算模拟出Marotto 混沌吸引子,同时还发现系统中存在周期14轨和周期16轨,这些复杂动态的发现丰富了对此系统的理解㊂参考文献:[1] 曲良辉,都琳,胡海威,等.电磁刺激对FHN 神经元系统的调控作用[J].动力学与控制学报,2020,18(1):40-48.QU L H,DU L,HU H W,et al.Regulation of electro⁃magnetic stimulation on FHN neuronal system[J].Jour⁃nal of Dynamics and Control,2020,18(1):40-48.(in Chinese)[2] 武春艳.神经元FitzHugh⁃Nagumo 模型的动力学分析[D].太原:太原理工大学,2015.WU C Y.Dynamical analysis of the neuronal FitzHugh⁃Nagumo model [D ].Taiyuan:Taiyuan University of Technolgy,2015.(in Chinese)[3] HODGKIN A L,HUXLEY A F.A quantitative descrip⁃tion of membrane current and its application to conductionand excitation in nerve[J].Journal of Physiology,1952,117(4):500-544.[4] FITZHUGH R.Impulses and physiological states in theo⁃retical models of nerve membrane[J].Biophysical Jour⁃nal,1961,1(6):445-466.[5] NAGUMO J,ARIMOTO S,YOSHIZAWA S.An activepulse transmission line simulating nerve axon [J].Pro⁃ceedings of the IRE,1962,50(10):2061-2070.[6] HAYASHI M.A note on the uniqueness of the closed or⁃bit of the FitzHugh -Nagumo system [J].Quarterly ofApplied Mathematics,2000,58(1):171-176.㊃421㊃北京化工大学学报(自然科学版) 2023年[7] ROCŞOREANU C,GIURGIŢEANU N,GEORGESCUA.Connections between saddles for the FitzHugh -Nagu⁃mo system [J].International Journal of Bifurcation and Chaos,2001,11(2):533-540.[8] JING Z J,JIA Z Y,CHANG Y.Chaos behavior in thediscrete FitzHugh nerve system [J].Science in China (Series A),2001,44(12):1571-1578.[9] ZHAN F B,LIU S Q.A Hénon⁃like map inspired by thegeneralized discrete⁃time FitzHugh -Nagumo model[J].Nonlinear Dynamics,2019,97(10):2675-2691.[10]MAROTTO F R.Snap⁃back repellers imply chaos in R n [J].Journal of Mathematical Analysis and Applicaions,1978,63(1):199-223.[11]MAROTTO F R.On redefining a snap⁃back repeller[J].Chaos,Solitions and Fractals,2005,25(1):25-28.Chaos in a discrete FitzHugh -Nagumo modelCHEN XiaoNan CHANG Yu * CHEN Jiao YANG RuiFeng(College of Mathematics and Physics,Beijing University of Chemical Technology,Beijing 100029,China)Abstract :Chaos phenomena in a discrete FitzHugh -Nagumo nervous model have been investigated.The existence of chaos in the sense of Marotto is analyzed theoretically.Numerical calculation studies for Lyapunov exponent dem⁃onstrate various complex dynamics,such as chaotic attractors,and period⁃14,and period⁃16orbits.Key words :discrete FitzHugh -Nagumo model;chaos in the sense of Marotto;Lyapunov exponent(责任编辑:吴万玲)㊃521㊃第2期 陈晓楠等:一类离散神经系统中的混沌存在性。
【计算机科学】_智能算法_期刊发文热词逐年推荐_20140723
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人脸识别 人工智能 k均值聚类 鲁棒性 鲁棒估计 高阶逻辑 高阶交叉累量 高维数据 高级语义 高斯过程隐变量模型 高斯混合模型 高光谱遥感图像 骨架提取 马尔可夫链 马尔可夫决策过程 风险过程 风险系数 风险加权相似度 频繁项集 频繁闭项集格 频繁闭项集 频繁模式树 频繁模式挖掘 频繁模式增长算法 频繁模式 领域本体 领域学习 预留空间 预测 非阻塞 非连续介词短语 非线性系统 静音检测 震荡性因子 集成神经网络 集成 集合自相关度 集合相关度 隶属度特征 障碍约束 隐马尔可夫模型 隐马尔可夫树模型 随机化回答 防火墙 阈值 闭合模式 量子粒子群优化 重要系数 采样 遥感影像 遥感图像 逻辑信息系统 速率控制 速度属性
消歧 泛化能力 模糊聚类 模式匹配 模式分类 机器学习 微粒群算法 增量算法 增量更新 基于密度的聚类 图像压缩 图像匹配 图像加密 四向 变换域 初始聚类中心 函数优化 几何攻击 决策树 关系数据库 入侵检测 信息隐藏 依赖度 人脸检测 人工神经网络 roughset k-means算法 agent adaboost 黎曼法坐标 黄瓜霜霉病 鲁棒性 高频强调滤波 高频变异 高维数据 高维形象几何与仿生信息学 高码率编码 高性能科学计算 首尾排序 颠簸 颜色量化 频繁项集 频繁项目集 频繁项 频繁访问页组 频繁模式挖掘 频繁序列集 频繁字串 频繁子树挖掘 频度中心 预选取失效 预测结构 预测模型 顶点射线
理解临床试验随机化
我们以区组长度4为例：
1. 2.
3. 4.
一个区组内的4个研究对象可以有6种排列方式：1. AABB, 2. ABAB, 3. ABBA, 4. BAAB, 5. BABA, 6. BBAA 确定好所有的排列形式后，接下来需要将6个区组随机排列。我们可以用 各种方式（如SPSS、Excel、SAS等）产生一串随机数字，比如： 92591264823981721367278057575098834352688429029…… 因为只有6种排列方式，因此可以只选择1-6之间的数字， 25126423121362555343526422…… 按照上述随机数字排列区组。当然，也可以采用其它方法随机排列区 组。 至此，区组随机化就完成了，两组人数完全相等。
对照
对照药的选择 对照药物的选择分为阳性对照药(即有活性的药物)和阴 性对照药(即安慰剂)。新药为注册申请进行临床试验， 阳性对照药原则上应选同一药物家族中公认较好的品种。 新药上市后为了证实对某种疾病或某种病症具有优于其 他药物的优势，可选择特定的适应症和选择对这种适应 症公认最有效的药物(可以和试验药不同结构类型、不同 家族但具有类似作用的药物)作为对照。 对照分组的英文术语为Arm。
分层随机化例子
随机化实施手段
信封法
随机方案编写好后，我们最常用的一种方法是使用信封进 行方案隐藏。以前使用的普通信封是“按顺序编码、不透 光、密封的信封”，即将每个分组方案装入一个不透光的 信封，信封外面写上编码，密封后交给研究者，待有研究 对象进入研究时，如果符合入选标准和排除标准，给病人 编号，再打开相应编号的信封，按信封内的分组方案进行 干预。每个研究对象所接受的治疗方案由生成的随机序列 决定。
随机号管理
研究NLP100篇必读的论文---已整理可直接下载
研究NLP100篇必读的论⽂---已整理可直接下载100篇必读的NLP论⽂⾃⼰汇总的论⽂集，已更新链接：提取码：x7tnThis is a list of 100 important natural language processing (NLP) papers that serious students and researchers working in the field should probably know about and read.这是100篇重要的⾃然语⾔处理(NLP)论⽂的列表，认真的学⽣和研究⼈员在这个领域应该知道和阅读。
This list is compiled by .本榜单由编制。
I welcome any feedback on this list. 我欢迎对这个列表的任何反馈。
This list is originally based on the answers for a Quora question I posted years ago: .这个列表最初是基于我多年前在Quora上发布的⼀个问题的答案:[所有NLP学⽣都应该阅读的最重要的研究论⽂是什么?]( -are-the-most-important-research-paper -which-all-NLP-students-should- definitread)。
I thank all the people who contributed to the original post. 我感谢所有为原创⽂章做出贡献的⼈。
This list is far from complete or objective, and is evolving, as important papers are being published year after year.由于重要的论⽂年复⼀年地发表，这份清单还远远不够完整和客观，⽽且还在不断发展。
宁波大学3809智能数据处理18-20年真题
科目代码: 3809 科目名称：智能系统
1. 机器学习通常可分为指导性学习和非指导性学习，学习模型则可分为生成模型和
判别模型二类。
假定现在要完成以下的任务：
（a）函数拟合与插值；（b）聚类分析；（c）模式识别，
请简要解释以下学习模型各自属于生成模型还是判别模型，可以胜任哪种任务：（1）深度学习网络，(2)RBF网络，(3)Boltzmann机，（4）SOM网络。
(10%) 2. 如果将异或（XOR）问题推广为3输入的parity问题，要求输入和输出实现如下
真值表：
输入1 输入2 输入3 输出
0 0 0 0
0 0 1 1
0 1 0 1
0 1 1 0
1 0 0 1
1 0 1 0
1 1 0 0
1 1 1 1
请设计一个多层网络实现3-parity，并给出相应的学习算法。
(12%)
3. Hopfield网络是全相连的反馈型网络，可以用于实现“吸引子”联想记忆，如果
要使一个Hopfield网络同时记住“A”、“I”、“Y”三个字母（3x4点阵），试为其设计一个合理的结构，并给出学习算法和具体的网络权值。
(12%)
科目代码: 3809 科目名称：智能系统。
社会学专业词汇中英文对照
学而不思则惘，思而不学则殆社会学专业词汇（按中文拼音首字母排序）B暴民：mob比拟法：analogical method比例抽样：proportionate sample不可知论：agnosticism变态心理学：abnormal psychology不完全归纳：incomplete induction边际效用递减：law of diminishing marginal utility 柏拉图式爱情：Platonic loveC丛众：conformity残疾人：the handicapped参考书目：bibliography参考群体：reference group成人教育：adult education初婚年龄：age at first marriage垂直流动：vertical mobility出身群体：descent group抽样误差：sampling error抽样范围：sampling frame参与式观察：participant observationD代沟：generation gap对照分析：contrastive analysis定性分析：qualititive analysis定量分析：quantitative analysis定额抽样：quota sample多重人格：multiple personality地位流动：status mobility第一手资料：primary data第二手资料：raw data单因素实验：single-factor experiment地域性流动：geographical mobilityF法人：fictitions person反隔离：desegregation犯罪学：criminology父居家庭：patrilocal family父系亲属：agnate 父子关系：filiation分析性研究：analytical research封闭式监管：close custody封闭型问题：closed question分层随机抽样：stratified random sample G规范：norms更年期：menopause过激主义：ultraism个案研究：case study个人主义：individualism归属需求：need to belong个人崇拜：personality cult功能主义：functionalismH行话，黑话：argot横坐标：abscissa合理趋势：rational trend霍桑效应：Hawthorne effect婚姻调适：marriage adjustment宏观分析：macroscopic analysis黄金分割：golden section互补角色：complementary roleJ家谱：family religrees截点：cut-off point拒答率：refusal rate绝对值：absolute value监护人：chaperonage角色冲突：role conflict角色距离：role distance角色紧张：role strain金钱崇拜：mammon worship间接暗示：indirect suggestion价值中立：value free价值判断：value judgement集体行动：collective action家庭规模：family size家庭不和：disharmony of family家庭制度：family institution近亲繁殖：inbreeding寄宿学校：boarding school教育程度：educational attainment继嗣规则：descent rule阶级分化：class differentiation教条主义：dogmatism经验主义：empiricism介入变量：intervening variable集思广益法：brainstorming method 经验我、客体我：empirical selfK克己：self-denial控制论：cybernetics控制组：control group刻板印象：stereotype可婚年龄：marriageable age框架分析：frame analysis跨文化方法：cross-cultural methodL量变：quantitative change列表：tabulation理想类型：ideal type利他主义：altruism利己主义：egoism老年痴呆：senile dementiaM目测：eye measure民法：civil law母爱：maternal love疯人院：mad house美国化：americanization母居家庭：matrilocal family民意测验：public opinion poll描述性概念：descriptive concept摩擦性失业：frictional unemployment 迷惘的一代：lost generationN能动性：activeness年龄优势：age domination年龄构成：age composition男性女化：effemination内化角色：internalized roleandrocentric theorymean agehorizontal mobility universal patternpair analysisbystander effectkin groupgroup climate groupthinkmass actiontrend analysisemotional contagion emotional traumadissociation of personality need for cognition identity crisis humanitarianismupward mobilityfittest to survivedepth/intensive interview tree analysisdual attitudesfair sampleaberrant behavior社会适应：social adaptation社会惯性：social inertia受控试验：controlled experiment试点调查：pilot investigation睡眠者效应：sleeper effect适应性反应：adaptation reaction社会决定论：agelicism社会改善论：meliorism生物决定论：biological determinism 双职工家庭：dual-career family随机化设计：randomized design实验室实验：laboratory experiment 说明性分析：explanatory studyT他杀：homicide胎儿：fetus推论：deduction同化：assimilation特殊性：particularism退伍军人：veteran统计假象：statistical artifact态度量表：attitude scale通俗文化：popular culture逃避现实：retreat from reality探索性研究：exploratory studyW问卷：questionnaire伪科学：pseudo-science文化促进：cultural acceleration微观分析：microscopic外来援助：extrinsic aid外显行为：manifest behavior文献研究：library research外向性格的人：extrovertX酗酒：alcoholism信度：credibility刑法：criminal law谢金：acknowledgement money享乐主义：hedonism雪球效应：snowball effect信息过滤：information filtering文化偏见：bias of culture sexismmental agepsychic gratificationmental healingdownward mobilityactualismacademic freedomaction schemesystematic sampleliner trendlearned helplessnesssmall group researchselective retentionnature-nurture debatedemand-deficiency unemploymentmail questionnaireabnormal curveaccidental pregnancycausal nexusraw datalogic-in-useempathysample statisticsfinite populationgrouped datamonogamous familyspecial vocabularyguilt complexgrowth curvegenocracyautosuggestionnatural selectionself-awarenessself-concept自我表露：self-disclosure 自我展示：self-presentation 自我监控：self-monitoring 祖先崇拜：ancestor cult self-administered questionnaire focused interviewdefensive sensitivity。
厌恶与恐惧面孔的记忆编码、保持、提取
收稿日期: 2018-01-13
* 国家自然科学基金(31571120)、国家基础研究计划(973 项目, 2014CB744600)、深圳市基础研究自由探索项目(JCYJ20170302143246158)
资助。 通信作者: 蒋冬红, E-mail: jiangdh@
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ica 关键词 短时记忆; 编码; 记忆保持; 记忆提取; 负性情绪; 厌恶
分类号 B842
olog 1 引言 ch 记忆包含编码、保持(巩固)和提取(检索)三个
y 主要阶段。通常来说, 情绪性信息会在记忆的各个 Ps 阶段导致记忆增强(LaBar & Cabeza, 2006)：在编码
2013; Cisler & Olatunji, 2010; Krusemark & Li, 2013; Liu, Zhang, & Luo, 2015; You & Li, 2016; Zhang, Liu, Wang, Ai, & Luo, 2017; Zimmer, Keppel, Poglitsch, & Ischebeck, 2015)。既然不同种类的负性 情绪能对注意产生不同的影响, 那他们可能对记忆
in 了更强的表征, 从而使被试在记忆提取时可回忆起更多的细节, 对记忆提取的信心更足(提取阶段 P3)。这后两条发 S 现是导致行为层面上厌恶情绪记忆优于恐惧情绪记忆的原因。本研究为“厌恶比恐惧具有更强的记忆增强效应”提
供了高时间分辨率的脑活动层面的证据, 从而进一步揭示了负性情绪增强记忆的认知机制。
图片比正确再认的恐惧和悲伤图片更强地激活了 回忆的项目比回忆失败的项目在编码和提取阶段
《传播研究方法》第八讲
抽样类型
原则
便利样本Haphazard
样本的选取主要考虑它们是否便利于收集、研究。
目的样本 Purposive
尽可能收集到符合某一标准的全部样本。
配额样本 Quota
复习：概率抽样的逻辑和理论
总体（Population）：我们感兴趣的、试图概括的群体或集合体。如：全国人口 要素（Element）：构成总体的单位，也是样本所包含的内容。 在一个既定研究中，要素与分析单位往往是相同的。要素用于抽样，分析单位用于资料分析。 样本率（sampling ratio）：样本个案数和总体之比，即n/N. 例：总体包含50,000人，研究者从中抽取150人作为样本，则样本率为
参数（parameter）：对总体中某变量的概括性描述。 统计值（statistic）：对样本中的变量的概括描述，并被用来估测总体参数。
统计值 Statistic
样本框 Sampling Frame
总体（Population）
参数 Parameter
抽样过程 Sampling Process
50/50
60/40
70/30
80/20
90/10
100
10
9.8
9.2
8
6
200
7.1
6.9
6.5
5.7
4.2
300
5.8
5.7
5.3
4.6
3.5
400
5
4.9
4.6
4
3
500
4.5
4.4
多项式回归与响应面分析的原理及应用
D01:10.13546/ki.tjyjc.2020.08.007 广他~----------------!理论探讨多项式回归与响应面分析的原理及应用陶厚永，曹伟(武汉大学经济与管理学院，武汉430072)摘要：相较于客观测量一致性研究问题的差异分数方法，多项式回归与响应面分析能更为深入地探究两 个变量间的复杂关系。
基于比较视角，文章阐述了如何正确地检验两个变量的一致性程度、同方向变化和反方 向变化三种情形对结果变量的影响，并扼要分析其检验逻辑的合理性。
此外，还重点探讨了如何检验有调节变 量的和有中介变量的多项式回归，同时运用一个实例演示如何分析和汇报数据结果，并指出了运用多项式回归 与响应面分析进行实证研究可能的发展方向。
关键词：多项式回归；响应面分析；比较视角；一致性中图分类号：B841 文献标识码:A 文章编号：1002-6487(2020)08-0036-050引言在组织行为与人力资源管理领域研究中，运用多项式 回归与响应面分析处理一致性问题逐渐得到认可，但目前 相关的理论研究成果并不多'通过对发表组织行为与人 力资源管理的五本国际顶级期刊(Academy of Management Joumal、JournalofAppliedPsychology、JoumalofManage—ment、JoumaIofOrganizationalBehavior、OrganizationalBe—havior and Human Decision Processes)以及中文社会科学引 文索引（CSSCI)期刊的检索发现，在2008—2017年这十年 间，运用多项式回归与响应面分析处理一致性问题的文章 在数量上虽呈上升趋势，但整体数量仍然偏少。
本文检索到2008—2017年五本国际顶级期刊发表关于一致性主题 文章的数量为37篇(检索主题词为congruence)，然而运用 多项式回归与响应面分析方法的文章数量只有16篇，仅 占43.2%。
Running title Combining multiple datasets
Combining Multiple Datasets in a Likelihood Analysis: Which Models are Best?Tal Pupko1,3, Dorothée Huchon2, Ying Cao1, Norihiro Okada2, Masami Hasegawa11The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato-ku, Tokyo 106-8569, Japan2Tokyo Institute of Technology, Faculty of Bioscience and Biotechnology, Molecular Evolution Laboratory, 4259 Nagatsuta-cho, Midori-ku, 226-8501, Yokohama, Japan3Corresponding author:e-mail: tal@ism.ac.jpTel: 81-3-5421-8780Fax: 81-3-5421-8796Key words: Combining datasets, phylogeny, maximum likelihood, Mammalia, molecular evolutionRunning title: Combining multiple datasetsAbstractUntil recently, phylogenetic analyses have been routinely based on homologous sequences of a single gene. Given the vast number of gene sequences now available, phylogenetic studies are now based on the analysis of multiple genes. Thus, it has become necessary to devise statistical methods to combine multiple molecular datasets. Here, we compare several models for combining different genes for the purpose of evaluating the likelihood of tree topologies. Three methods of branch length estimation were studied: assuming all genes have the same branch lengths (concatenate model); assuming that branch lengths are proportional among genes (proportional model); or assuming that each gene has a separate set of branch lengths (separate model). We also compared three models of among-site rate variation: the homogenous model, a model that assumes one gamma parameter for all genes, and a model that assumes one gamma parameter for each gene. On the basis of two nuclear and one mitochondrial amino-acid datasets, our results suggest that, depending on the dataset chosen, either the separate model or the proportional model represent the most appropriate method for branch length analysis. For all datasets examined, one gamma parameter to each gene represents the best model for among-site rate variation. Using these models, we analyzed alternative mammalian tree topologies and describe the effect of the assumed model on the maximum likelihood tree. We show that the choice of the model has an impact on the best phylogeny obtained.IntroductionIn the last 30 years, vast improvements in DNA sequencing methods have effected an exponential increase in the number of gene entries in databases worldwide (e.g., International Human Genome Sequencing Consortium 2001) and given scientists access to entire genome sequences of many organisms. Access to large amounts of sequence data has spawned a revolution in the understanding of biological diversity (see Graur and Li 1999). For example, in a recent analysis, Murphy et al. (2001) examined variations among 18 homologous gene segments (nearly 10,000 base pairs) in order to infer the mammalian evolutionary tree. The sequence data explosion is not without its caveats, however, as it brings with it the need for development of methods to efficiently combine information from multiple molecular datasets. Examples of multiple datasets are: (1) several genes; (2) the three codon positions of a protein-coding sequence; and (3) different parts of the protein-coding sequence that correspond to different secondary structures (e.g., alpha-helix, beta-sheet). Since different genes likely have different evolutionary constraints, the evolution of different genes might be best described by different sets of parameters. However, when statistically analyzing a dataset, adding new parameters is not always justified and can lead to erroneous conclusions (for examples, see Burnham and Anderson 1998). Thus, when modeling sequence evolution in a Maximum Likelihood (ML) framework of tree reconstruction (Felsenstein 1981), investigators must strive to determine a median set of parameters that neither assumes too few parameters nor results in ‘over fitting’ by assuming too many. An example of a significant improvement in sequence evolution models is the parameterization of among-site rate variation. By adding only one parameter to describe the site-rate variation distribution, a substantial increase in the log likelihood is typically gained(Yang1996a). Not only is this addition of a single parameter reasonable in a statistical and biological sense, but it has also been shown to affect resulting phylogenetic conclusions (Sullivan and Swofford 1997). Cases in which the addition of new parameters is statistically unjustified are rarely published, but such pitfalls are discussed by Nei and Kumar (2000; pp. 154-155) and Takahashi and Nei (2000).When analyzing a multiple sequence alignment, one must assume an underlying evolutionary model. This model includes the tree topology, the branch lengths, the rate heterogeneity among sites, and the substitution probabilities. All of these parameters might change from gene to gene. For example, the tree topology of various genes might not be the same because of horizontal gene transfer. Similarly the substitution model might vary from gene to gene, because of different evolutionary constraints, or because of differences in GC content. In this paper, we focus on the fitting of different branch-lengths models, and rate-heterogeneity models to several protein datasets.The number of branch length parametersFor an unrooted tree topology T, with n sequences, the number of branches is 2n-3. We denote branches by t1,…,t2n-3. Assume now that we have two datasets (e.g., two different genes), each one with n homologous sequences. One way to analyze a combination of these datasets is to concatenate the sequences and evaluate the resultant branch lengths. We refer to this model as the “concatenate model”. In such a scenario the joint probability would be:P(data1 & data2 | T, t1,…,t2n-3) = P(data1 | T, t1,…,t2n-3) · P(data2 | T, t1,…,t2n-3)The number of free parameters here is 2n-3. (This model assumes that both genes have the same branch length.) Another approach is to assume that branch lengths for the two genes are independent (i.e., each gene is analyzed separately). We refer to this model as the “separate model”. In this case the joint probability would be:P(data1 & data2 | T, t11,…,t2n-31, t12,…,t2n-32) = P(data1 | T, t11,…,t2n-31) · P(data2 | T, t12,…,t2n-32)where superscripts denote the dataset attributes. In our present work, we study these two alternative models and explore a third alternative for combining datasets, namely the “proportional branch lengths” approach first suggested by Yang (1996b).The proportional branch lengths approachThe proportional branch lengths approach assumes that branch lengths for two trees are the same, up to a scaling factor r. Thus, if t1,…,t2n-3 are the branches of the first gene, the branch lengths of the second gene would be rt1,…, rt2n-3. . This scaling factor r corresponds to a gene-specific rate that is assigned to each gene, and for n genes we have n gene-specific rate factorsr1,…r n.. The average r should be equal to 1.0. We refer to this model as the “proportional model”. For two datasets the joint probability is:P(data1 & data2 | T, t1,…,t2n-3, r1, r2 ) = P(data1 | T, t1,…,t2n-3, r1) · P(data2 | T, t1,…,t2n-3, r2)Consequently, the total number of parameters for two genes under this proportional model is 2n-3+1 = 2n-2. The number of parameters for n genes for each of the three models is summarized in Table 1.The biological meaning of the proportional model relies on the assumption that the rate in each branch is a multiplication of two rates: the rate of the specific gene multiplied by the rate of the specific lineage. It is the specific lineage’s rate that is common to all genes under the proportional model. In contrast the concatenate model assumes that all genes’ rates and all lineages’ rates are the same, while the separate model assumes that the rate in each lineage is independent among genes.The number of among-site rate variation parametersWe consider three possible models of among-site rate variation. The first model assumes that all sites have the same rate of evolution (“homogenous” model), the second model assumes one gamma rate parameter for all genes (“1-GAM” model), and the third model assumes a separate gamma parameter for each gene (“N-GAM” model).We compare all nine combinations of models with respect to likelihood (concatenate-homogenous, concatanate-1-GAM, concatenate-N-GAM, proportional-homogenous, proportional-1-GAM, proportional-N-GAM, separate-homogenous, separate-1-GAM, separate-N-GAM). With respect to branch lengths, we show that the proportional and separate models are always better than the concatenate model. Selecting between these two models depends on the specification of the dataset under study. For some datasets the proportional model represents thebest model, while for others, the separate model is the best. With respect to the number of gamma parameters, the N-GAM model is the best model for all datasets included in our study.Material and MethodsSequencesComputations were based on three protein alignments: Madsen et al. (2001), Murphy et al. (2001), and an updated mitochondrial dataset of Nikaido et al. (2001).Madsen datasetThe Madsen nucleotide alignment includes 28 species for four independent nuclear genes: the Alpha-2B adrenergic receptor (A2AB, 344 sites), the breast cancer susceptibility gene (BRCA1, 557 sites), the interphotoreceptor retinoid binding protein (IRBP, 301 sites) and the von Willebrand Factor (vWF, 338 sites). The sequence of the golden mole (Amblysomus hottentotus) and the Madagascar hedgehog, (Echinops telfairi) were not included because sequence data was not available for IRBP. The BRCA1 sequence of the thick-tailed opossum (Lutreolina crassicaudata; accession number: AY057826) was added manually to the Madsen alignment.Murphy datasetAmong the 18 genes considered in the nucleotide alignment of Murphy et al. (2001), we excluded the seven non-coding genes. Because we require that all genes share the same speciessampling (i.e., no missing sequences), three more genes for which marsupial sequences were unavailable were excluded. Two genes with a poor species sampling were also excluded. This exclusion allows our analysis to maintain a large and diversified species sampling where all sequences are available for all genes. The final alignment includes 46 species for six nuclear genes: adenosine A3 receptor (ADORA3, 107 sites), the Menkes disease gene (ATP7A, 220 sites), brain-derived neurotrophic factor (BDNF, 182 sites), the cannabinoid receptor 1 (CNR1, 219 sites), the sphingolipid G-protein-coupled receptor 1 (EDG1, 199 sites), and the zinc finger protein X-linked (ZFX, 67 sites).Mitochondrial datasetThe mitochondrial dataset included 56 species comprising the 43 complete mitochondrial coding sequences analyzed by Nikaido et al. (2001) together with the following sequences: (1) asiatic shrew, Soriculus fumidus AF348081 (2) long-tailed bat, Chalinolobus tuberculatusAF321051 (3) little red flying fox, Pteropus scapulatus AF321050 (4) northern brown bandicoot, Isoodon macrourus AF358864 (5) gymnure, Echinosorex gymnura AF348079 (6) american pika, Ochotona princeps AF348080 (7) barbary ape, Macaca sylvanus AJ309865 (8) slow loris, Nycticebus coucang AJ309867 (9) white-fronted capuchin, Cebus albifrons AJ309866 (10) cane rat, Thryonomys swinderianus AJ301644 (11) vole, Volemys kikuchii AF348082 (12) tree shrew, Tupaia belangeri AF217811, and (13) small Madagascar hedgehog, Echinops telfairi AJ400734. The twelve H-strand mitochondrial protein coding genes are: ND1 (313 sites), ND2 (313 sites), COX1 (512 sites), COX2 (225 sites), ATP8 (32 sites), ATP6 (201), COX3 (259), ND3 (104 sites), ND4L (94 sites), ND4 (438 sites), ND5 (526 sites), and Cyt b (375 sites). The overlapping regions between ATP6 and ATP8, and between ND4 and ND4L, were excluded.All nucleotide alignments were translated into amino acid alignments. To agree with the reading frame, some minor changes were made to the alignments of Madsen et al. (2001) and Murphy et al. (2001). For all genes, gap positions were excluded from the analysis. If data for certain positions was missing in >5% of the species studied then such positions were excluded from the analysis. All the protein alignments and accession numbers are available at:http://evolu3.ism.ac.jp/~tal/combining.htmlTree topologiesFor each dataset, four different topologies were considered: a morphological tree, a mitochondrial tree, and two nuclear trees (Madsen and Murphy topologies). Since species sampling differed among the four datasets, the four trees were slightly different with respect to the dataset used. For the mitochondrial dataset, the morphological and mitochondrial trees are presented in Figures 1 and 2, respectively. For the Murphy dataset, the Murphy tree is given in Figure 3, and for the Madsen dataset the Madsen tree is given in Figure 4. All 12 trees are available at: http://evolu3.ism.ac.jp/~tal/combining.html.Morphological treeFor all datasets, morphological trees were based on the phylogeny of McKenna and Bell (1997) (e.g., Fig. 1). The topology of Novacek (1992) was adopted for relationships between clades that were not determined by McKenna and Bell (i.e., among the grandorders of Epitheria). Any relationships that were not fully resolved by the above criteria were subsequently chosen based on the nuclear topology of Murphy et al. (2001).Mitochondrial treeThe mitochondrial tree is based on Cao et al. (2000). However, the position of the rodents was chosen in agreement with Reyes, Pesole, and Saccone (2000), and Mouchaty et al. (2001). The position of the vole among the rodents was chosen in agreement with morphological data (McKenna and Bell 1997). Among cetartiodactyls, the alpaca and the pig were sister clades in agreement with Arnason et al. (2000). The relationships among bats were chosen in agreement with Nikaido et al. (2001) and McKenna and Bell (1997). The shrews and moles were placed as a sister clade of the bats, in agreement with Nikaido et al. (2001). The Afrotheria phylogeny was in agreement with Murphy et al. (2001). Xenarthra was placed as a sister clade of Afrotheria, in agreement with Reyes, Pesole, and Saccone (2000). The position of the rabbit, tree shrew, primate and hedgehog was in agreement with Schmitz, Ohme and Zischeler (2000). The lagomorphs were considered monophyletic. The relationship among primates followed McKenna and Bell (1997). Hedgehog and gymnure were placed together. Finally, relationships among marsupials were taken from Phillips et al. (2001). For other relationships we followed Murphy et al. (2001). Figure 2 presents the mitochondrial tree for the mitochondrial dataset.The Murphy treeThis tree was based on Murphy et al. (2001). McKenna and Bell (1997) was followed for relationships that were not determined by Murphy et al. Figure 3 presents the Murphy tree for the Murphy dataset.The Madsen treeThis tree is based on Madsen et al. (2001, figure A). Murphy et al. (2001) and McKenna and Bell (1997) were followed for relationships that were not determined by Madsen et al. Figure 4 presents the Madsen tree for the Madsen dataset.ModelIn this study, models based on amino acid sequences were used. The replacement probabilities among amino acids were calculated with the JTT matrix (Jones et al. 1992) for the nuclear genes and the REV model (Adachi and Hasegawa 1996) for the mitochondrial genes. However, the approach presented here is also valid for nucleotide sequences and for any substitution model. The alpha parameter of the gamma distribution was estimated with the ML method. The discrete gamma distribution with 4 categories was used (Yang 1994). A program implementing all 9 models described above was written in C++ and is available athttp://evolu3.ism.ac.jp/~tal/combining.html. Procedures for calculation of the likelihood functions were adapted from the SEMPHY program (Friedman et al. 2001).To compare between the different models, the Akaike Information Criterion (AIC) defined as AIC = -2 × log likelihood +2 × number of free parameters was used (Sakamoto, Ishiguro, and Kitagawa 1986). A model with a lower AIC is considered a more appropriate model (Sakamoto, Ishiguro, and Kitagawa 1986). To evaluate if the AIC values of two models are significant, the test of Linhart (1988) was used. When comparing different tree topologies for the same model, one-tailed Kishino-Hasegawa test was used (Kishino and Hasegawa 1989).ResultsWe examined the effect of different branch length models as well as the number of gamma parameters (alpha) when combining different genes for phylogenetic analysis. For all datasets and all trees, the lowest AIC values (indicative of the best model) were achieved by assuming a different gamma parameter for each gene (the N-GAM model). This result held for all categories of branch length models. Further, AIC values were always lower when one gamma parameter for all genes was assumed (the 1-GAM model) compared with the model that assumed no among-site rate variation (the homogenous model). Hence, we present detailed results (i.e., the log-likelihoods, alpha parameter, and gene-specific rate factors) only for the best trees under the N-GAM model (Table 2). For all other cases only the sum of the log-likelihoods and the AIC values are presented (Table 3).Mitochondrial datasetThe proportional method assigns a specific rate for each gene. This gene-specific rate can be used to rank the evolutionary rate among different genes. For example, in the mitochondrial tree the N-GAM model yielded a gene-specific rate of 1.48 for the ATP8 gene, while that for cytochrome oxidase subunit 1 (the ‘slowest’ gene) was 0.29 (Table 2a). Only minor changes in the gene-specific rates were observed when other tree topologies were assumed.For the twelve mitochondrial genes studied (Table 3a), the AIC values achieved using the proportional model were significantly lower than those obtained with either the concatenatemodel or the separate model. For example, the N-GAM model for the mitochondrial tree yielded an AIC value of 182,262.6 for the proportional model while the separate analysis and concatenate models gave AIC values of 182,483.55 and 182,619.42, respectively. This difference of 221 between the proportional model and the separate model is significant (P value < 0.05). Thus, the proportional model is significantly better than both the separate model and the concatenate model. However, the AIC difference of 136, between the separate model and the concatenate model (Table 3a) is not statistically significant.Among the four different tree topologies, for all models the most likely tree was the mitochondrial tree. For the N-GAM model with proportional branch length, the log likelihood of the mitochondrial tree was –90,999.3 while the second best was the Murphy tree at –91,022.96. This difference of 23.66 ± 47.84 corresponds to a P value of 0.31 using the Kishino-Hasegawa test (Kishino and Hasegawa 1989). Hence, when using the proportional model the mitochondrial tree is not significantly different from the Murphy tree. Similar results were obtained when comparing the mitochondrial tree and the Madsen tree (P value of 0.21 using the Kishino-Hasegawa test). However, the morphological tree was rejected when compared to all other trees (log-likelihood difference > 742; P value < 0.001).Murphy datasetFor the six nuclear genes studied, again, the AIC values achieved using the proportional model were significantly lower than those obtained with either the concatenate model or the separate model. For example, the N-GAM model for the Madsen tree yielded an AIC value of 23,287.7 for the proportional model while the separate analysis and concatenate models gave23,464.2 and 23,427.3, respectively (Table 3b). This difference of 176.5 between the proportional model and the separate model is significant (P value < 0.05). As for the mitochondrial dataset the AIC differences between the separate model and the concatenate model were not significant. The most likely tree topology for all models is the Madsen topology, in contradiction with the observations of Murphy et al. (2001) except for the concatenate-N-GAM model where the best tree is the Murphy tree. This discrepancy most likely arises from our use of amino acid datasets instead of nucleotide datasets, as well as differences in alignment. However, the difference in log-likelihood between the Madsen topology and the Murphy topology is very small and non-significant in each case (i.e., log-likelihood difference < 10; Table 3b). For example, for the proportional-N-GAM model, the log-likelihood difference between the Madsen and the Murphy tree topologies is 1.87 ± 8.22, corresponding to a P value of 0.41 by the Kishino-Hasegawa test. Assuming this model, both the mitochondrial tree and the morphological tree are significantly worse than the Madsen tree (log-likelihood difference > 44; P value < 0.01).Madsen datasetUnlike the results obtained for the other two datasets, the lowest AIC values for the Madsen dataset were obtained with the separate model regardless of the number of gamma parameters assumed. For example, the N-GAM model for the Murphy tree yielded an AIC value of 62,738.6 for the separate model while the proportional analysis and concatenate models gave 62,933.6 and 63,152. 2, respectively. This difference of 195 between the proportional model and the separate model is significant (P value < 0.01). Here, the proportional model is also significantly better than the concatenate model (P value < 0.01). The most likely tree topology was obtained for the Murphy topology, for all models considered. Surprisingly, the Murphy treeappears to be significantly better than all other tree topologies. For example, for the N-GAM-separate model, the log-likelihood difference between the Madsen (the second best tree) and Murphy tree topologies is 53.19 ± 20.62, corresponding to a P value < 0.05 by the Kishino-Hasegawa test.Tree searchIn the above analyses, we investigated the differences between the supports of four predetermined tree topologies under nine different models. As can be seen from table 3b, the model can have an impact on the best topology found. For the Murphy dataset under the concatenate-N-GAM model, the Murphy tree appears to be the best while under the all other models the Madsen tree is the best.To further determine the effect of the model on the tree topology we implemented a tree-search algorithm to find the most likely tree under each of the models. Because of computational limitations, the tree search was conducted on 14 taxa representing the main mammalian clades, using a subset of the mitochondrial dataset (Figure 5). Starting with various starting points (a neighbor joining tree, a tree based on the mitochondrial topology and a tree based on the Murphy topology), we searched the tree space for better trees through the nearest neighbors interchange (NNI) algorithm. We also limited our searches to the two best models found above (i.e. the proportional-N-GAM model and the separate -N-GAM model). The alpha parameters and the gene-specific rate s for this search were based on the corresponding N-GAM analysis of the complete mitochondrial dataset.We found different best trees under these two models. The ML tree under the N-GAM- proportional is given in Figure 5a, while the ML tree under the N-GAM-separate is given inFigure 5b. Under the proportional-N-GAM model, the glires (rodents and rabbit) are monophyletic. The glires are related to a man + tree shrew clade. In the separate model, the tree-shrew clusters with the rabbit rather than with the man hence, the glires are not monophyletic. Another difference concerns the Laurasiatheria. In the N-GAM- proportional model, the Laurasiatheria are divided to two clades: The first includes the mole and the bat. The second includes the whale, the horse and the cat. In this second clade, the horse and the whale cluster together. On the contrary, in the N-GAM-separate model, the whale is the first diverging taxa of the Laurasiatheria. However, in each model, the differences in log-likelihood between these two topologies are not significantly different: Under the proportional model, the log likelihood difference between the two trees is 13.3, while under the separate model, the difference in log likelihood between the two trees is 2.15. These differences are not significant based on Kishino-Hasegawa test (P value > 0.05; results not shown). Nevertheless, these results demonstrate that choosing among alternative models can lead to different best trees. Thus, choosing the best model is important not only to better model the molecular evolutionary process, but also for inferring phylogenetic relationships among taxa in general.DiscussionAssigning gene-specific rates for genesIn the proportional model, a specific rate is assigned to each gene. These rates can be used to classify genes, and estimating relative rates of sequence evolution can be used todetermine whether a gene is relevant for a specific phylogenetic analysis. Conserved genes (i.e., genes with lower evolutionary rates) are expected to give better estimates for deeper evolutionary divergences while fast-evolving genes can be used to resolve recent divergences. For example, Corneli and Ward (2000) used sequence similarity plots to empirically determine the relative rates of evolution of mitochondrial genes. The advantages of our method for determining gene-specific evolutionary rates lie in its statistical robustness (it is a maximum-likelihood estimate of the gene-specific rate) and its ability to combine specific model assumptions (the gamma distribution, the substitution model) into the estimation scheme. Furthermore, our method takes tree topology into consideration whereas sequence similarity plots do not.Model selectionCurrently, the method of concatenating sequences is most frequently used for analyzing multiple datasets (Reyes, Pesole and Saccone 2000; Madsen et al. 2001; Murphy et al. 2001). Conversely, our results show that both the proportional model and the separate model yield results that are superior to the concatenate model. This is in agreement with the result of Cao et al. (1998) who showed that, for mitochondrial data, separate analysis is superior to the concatenate method. However, selecting the superior of the separate and proportional models is a more complicated issue. The proportional model is more appropriate for the analysis of the mitochondrial and Murphy datasets while the separate model is favored for the Madsen dataset. The separate analysis is preferable when each gene is of sufficient length to allow the accurate determination of a separate set of branch lengths. In our study, the sequence lengths in the Madsen dataset were longer than those in the Murphy or mitochondrial datasets. When only thefirst 100 positions in each gene of the Madsen dataset were analyzed, the proportional model was the best model (data not shown). Another factor that can affect model selection is inconsistent branch length among different genes in a dataset. If, for example, significant rate acceleration occurred for only one gene in a specific clade, then analysis by the separate model would be justified. Thus, it is expected that the proportional model would be most appropriate when analyzing closely related sequences. We note that Yang (1996b) showed that the proportional model was superior to the separate analysis for a dataset composed of four parts: the first, second and third codon positions of six mitochondrial genes and a fourth part composed of eleven tRNA sequences. We speculate that this proportional model preference is due to the fact that the analysis of Yang considered only primate sequences.In our analyses, it proved more fruitful to assume a different gamma parameter for each gene rather than assuming a single gamma parameter for all genes. Each gamma distribution involves a shape parameter alpha. This alpha parameter determines the shape of the gamma distribution and is inversely related to the extent of the rate variation among sites. Some genes show substantial rate variance while others exhibit a more homogeneous distribution of the rate of different positions. For example, for the Murphy dataset, assuming the best model, the alpha parameter ranges from 0.93 for the ATP7 gene to 0.12 for the CNR1 gene (see Table 2b). We conclude that the substantial difference between the rate-distributions among genes is sufficient enough to justify a separate gamma parameter for each gene.Regarding the effect of the model on tree selection, our results show that the model chosen has an effect on the tree topology. It is expected that the model would also affect the。
孟德尔随机化Mendelianrandomization,MR
孟德尔随机化Mendelianrandomization,MR孟德尔随机化分析 Mendelian randomization,MR使⽤遗传变异作为⼯具变量，推断暴露因素与结局之间的因果关系，能有效克服混杂合反向因果问题所导致的偏倚。
1986年，Katan提出MR思想：由于配⼦形成时，遵循“亲代等位基因随机分配给⼦代”的孟德尔遗传规律，如果基因型决定表型，基因型通过表型⽽与疾病发⽣关联，因此可以使⽤基因型作为⼯具变量来推断表型与疾病之间的关联。
①⼯具变量Z与混杂因素U⽆关联；②⼯具变量Z与暴露因素X有关联；③⼯具变量Z与结局变量Y⽆关联，Z只能通过变量X与Y发⽣关联。
①变量X与Y之间的关联⼀定会受到潜在混杂因素U的影响，但⼯具变量Z与变量X以及Z与变量Y之间⽆潜在混杂因素影响；②变量X与结局Y之间的关联⽆法直接观察获得，因为⽆法直接测量变量X，但是Z是可测量的，并且Z与X直接的关联是已知的或者可测量的，并独⽴于其他因素⽽存在。
（/zhlxbx/20170427.htm）孟德尔随机化是在⾮实验数据中使⽤遗传变异来估计暴露和结局之间的因果关系，也称为“孟德尔解混杂”，它旨在给出因果关系的估计，不会因混杂因素⽽产⽣偏差。
孟德尔随机化的想法是找到与暴露有关的遗传变异（或多个变异），但与影响结果的⼈和其他风险因素⽆关，并且与结果不直接相关。
遗传变异与结果之间的任何关联都必须通过与暴露之间的关联来进⾏，因此暗⽰了暴露对结果的因果关系，这样的遗传变异将满⾜⼯具变量（IV）的假设孟德尔随机中，遗传变异被作为⼯具变量评估暴露对结局的因果效应，遗传变异满⾜⼯具变量的基本条件总结为：1）遗传变异与暴露有关。
2）遗传变异与暴露-结果关联的任何混杂因素均不相关3）改遗传变异不会影响结果，除⾮可能通过化瘀暴露的关联来实现。
尽管孟德尔随机化分析通常涉及单个遗传变异，但可以将多个变异⽤作单独的IV或组合为单个IV。
暴露：指假定的因果风险因素，有时称为中间表型，它可以是⽣物标志物(Biomarker)、⼈体测量指标(Physical measurement)或任何其他影响结果的风险因素(Risk factor)。
基与结合遗传算法结合的直觉模糊集的检索方法(英文翻译)
基与结合遗传算法结合的直觉模糊集的检索方法(英文翻译)北京理工大学，2009年卷。
18，第1号基与结合遗传算法结合的直觉模糊集的检索方法WAN G Xiao2yin (王潇茵) 1 , XU Wei2hua (徐卫华) 2 , HU Chang2zhen (胡昌振)计算机网络防御技术实验室，北京理工大学，北京100081，中国;2。
自动化站的陆军参谋航空系，北京100012，中国摘要：本文提出了一种基于直觉模糊理论和遗传算法相结合的新的图像检索方法,旨在解决旧的方法的缺点。
每个图像在垂直方向上被分割成一群数目恒定的子图像。
提取每个子图像的颜色特征以得到染色体编码。
我们认为，模糊的部分和直觉模糊犹豫程度与每个像素的彩色图像直方图有关。
某些功能，图像的模糊特征和直观模糊特征，一起使用来描述图像内容。
高效子图像组合根据选择操作，交叉和变异被选出来。
检索的结果是根据从这些子图像颜色特征组合而获得的。
测试结果表明这种方法可在不降低速度的情况下提高图像检索的精度。
其平均精度在80％以上。
关键词：直觉模糊，遗传算法，颜色直方图，图像检索随着计算机技术和网络技术迅速发展，有越来越多的信息在互联网上传播。
形象是重要信息载体，图像检索技术成为研究的重点。
图像检索最基础的任务是提取图像特征。
为了图像内容表示准确，形象特征应该有综合性和完整性。
但如果特征数量太多，那就不太好得到检索结果。
如何完全表达图像和移除不影响检索准确度的无用特征是一个问题。
利用模糊推理和遗传算法可以一定程度上解决这个问题。
到目前为止，这个系统的图像检索仍然是罕见的。
邹用粗糙的设置计算最简单的图像的视觉特征子集，并使用交互式遗传算法评价图像的功能[1]。
杨用算法估计交叉概率和突变概率基于模糊推理技术[2]。
Soodamani用基于先验知识和使用一个遗传算法—范式系统反馈路径的基础学习，来设定一个特征模板。
普遍的问题是逻辑模糊和遗传算法在优化搜索路径时不合适染色体编码进展。
如何使用马尔可夫链蒙特卡洛进行贝叶斯模型融合(九)
马尔可夫链蒙特卡洛（MCMC）是一种用于贝叶斯统计推断的强大工具。
通过MCMC方法，可以对多个模型进行融合，得出更准确的推断结果。
本文将介绍如何使用马尔可夫链蒙特卡洛进行贝叶斯模型融合。
马尔可夫链蒙特卡洛是基于马尔可夫链的一种蒙特卡洛方法。
马尔可夫链是一种具有马尔可夫性质的随机过程，即给定当前状态，未来状态的概率分布只与当前状态有关，而与过去状态无关。
蒙特卡洛方法则是一种通过随机抽样来近似求解问题的数值方法。
将这两种方法结合起来，就得到了马尔可夫链蒙特卡洛方法，用于对概率分布进行近似求解。
在贝叶斯统计推断中，我们常常需要对多个模型进行融合，得出对参数或未知量的推断结果。
而MCMC方法正是能够胜任这一任务的利器。
通过MCMC方法，我们可以对多个模型进行联合推断，得出更为准确的结果。
在使用MCMC方法进行贝叶斯模型融合时，首先需要确定要融合的多个模型。
这些模型可以是不同的概率分布模型，也可以是不同的参数模型。
接下来，需要构建联合分布模型，将这些模型进行融合。
这一步通常需要一定的数学推导和模型设计能力。
在确定了联合分布模型之后，就可以使用MCMC方法进行参数估计和推断。
MCMC方法会通过对联合分布模型进行随机抽样，从而近似求解得出参数的后验分布，进而得出推断结果。
MCMC方法有多种实现方式，其中最为经典的是Metropolis-Hastings算法和Gibbs采样算法。
Metropolis-Hastings算法是一种接受-拒绝算法，通过不断生成候选样本，并按照一定规则接受或拒绝这些样本，从而得到符合目标分布的样本。
而Gibbs采样算法是一种特殊的Metropolis-Hastings算法，它能够对联合分布模型的每个参数进行逐一抽样，从而更为高效地完成参数估计和推断。
在进行MCMC方法时，需要注意对初始值的选取和采样步长的调整。
初始值的选取会直接影响到MCMC方法的收敛速度和结果准确度，而采样步长的调整则可以有效地提高采样效率。
DS证据理论浙大
5.1 证据理论的发展简况
1、证据理论的名称
证据理论(Evidential Theory) Dempster-Shafer理论 Dempster-Shafer证据理论 DS (或D-S)理论
其它叫法：
Dempster规则 Dempster合成规则 Dempster证据合成规则
2、证据理论的诞生和形成
Outline
本章的主要参考文献 证据理论的发展简况 经典证据理论 关于证据理论的理论模型解释 证据理论的实现途径 基于DS理论的不确定性推理 计算举例
本章的主要参考文献（续1）
[5] Zadeh, L. A. Review of Shafer’s a mathematical theory of evidence. AI Magazine, 1984, 5:81-83. 【对证据理论进行质疑的经典文献之一】
[17] Yaghlane, B. B., et al. Belief function independence: I. The marginal case. International Journal of Approximate Reasoning, 2002, 29(1): 47-70.
[18] Yaghlane, B. B., et al. Belief function independence: II. The conditional case. International Journal of Approximate Reasoning, 2002, 31: 31-75.
[10] Smets, P, and Kennes, R. The transferable belief model. Artificial Intelligence, 1994, 66: 191-234.
模糊多准则决策方法
模糊多准则决策方法综述
在MCDM问题中,如果准则值或/和准则权系数为直觉 模糊数,称这类问题为基于直觉模糊集的MCDM问题。 由于没有实数与直觉模糊集的运算,使得求解这类决策 变得困难。基于直觉模糊数的TOPSIS方法、VIKOR 方法、规划方法及基于证据推理的求解方法被提出。 但相对基于模糊数的MCDM方法来说,基于直觉模糊 数的MCDM方法还显得太少。
模糊多准则决策方法综述
许多准则权系数和准则值确定的MCDM方法纷纷推广到FMCDM问题 中,提出了众多FMCDM方法，如模糊TOPSIS方法、模糊ELECTRE方 法和模糊PROMETHEE方法等。
目前,主要集中研究二类FMCDM问题：其一是准则权系数确定或为模 糊数且准则值为模糊数的MCDM问题,其二为准则权系数信息不完全确 定且准则值为模糊数的MCDM问题。
模糊多准则决策方法综述
1993年,Gau和Buehrer提出了Vague集[31],它 是模糊集的一种扩展。Vague集具有比模糊集 更好的表达不确定性的能力,已引起众多学者的 关注,被广泛应用于人工智能、决策分析、模式 识别和智能信息处理等领域。虽然1996年 Bustince和Burillo证明了Vague集是直觉模糊 集，但还有不少研究人员在研究基于Vague集 的FMCDM问题,提出了相应决策模型与方法。
直觉模糊多准则决策方法
直觉模糊多准则决策方法
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专八英语阅读
英语专业八级考试TEM-8阅读理解练习册（1）(英语专业2012级)UNIT 1Text AEvery minute of every day, what ecologist生态学家James Carlton calls a global ―conveyor belt‖, redistributes ocean organisms生物.It’s planetwide biological disruption生物的破坏that scientists have barely begun to understand.Dr. Carlton —an oceanographer at Williams College in Williamstown,Mass.—explains that, at any given moment, ―There are several thousand marine species traveling… in the ballast water of ships.‖ These creatures move from coastal waters where they fit into the local web of life to places where some of them could tear that web apart. This is the larger dimension of the infamous无耻的，邪恶的invasion of fish-destroying, pipe-clogging zebra mussels有斑马纹的贻贝.Such voracious贪婪的invaders at least make their presence known. What concerns Carlton and his fellow marine ecologists is the lack of knowledge about the hundreds of alien invaders that quietly enter coastal waters around the world every day. Many of them probably just die out. Some benignly亲切地，仁慈地—or even beneficially — join the local scene. But some will make trouble.In one sense, this is an old story. Organisms have ridden ships for centuries. They have clung to hulls and come along with cargo. What’s new is the scale and speed of the migrations made possible by the massive volume of ship-ballast water压载水— taken in to provide ship stability—continuously moving around the world…Ships load up with ballast water and its inhabitants in coastal waters of one port and dump the ballast in another port that may be thousands of kilometers away. A single load can run to hundreds of gallons. Some larger ships take on as much as 40 million gallons. The creatures that come along tend to be in their larva free-floating stage. When discharged排出in alien waters they can mature into crabs, jellyfish水母, slugs鼻涕虫，蛞蝓, and many other forms.Since the problem involves coastal species, simply banning ballast dumps in coastal waters would, in theory, solve it. Coastal organisms in ballast water that is flushed into midocean would not survive. Such a ban has worked for North American Inland Waterway. But it would be hard to enforce it worldwide. Heating ballast water or straining it should also halt the species spread. But before any such worldwide regulations were imposed, scientists would need a clearer view of what is going on.The continuous shuffling洗牌of marine organisms has changed the biology of the sea on a global scale. It can have devastating effects as in the case of the American comb jellyfish that recently invaded the Black Sea. It has destroyed that sea’s anchovy鳀鱼fishery by eating anchovy eggs. It may soon spread to western and northern European waters.The maritime nations that created the biological ―conveyor belt‖ should support a coordinated international effort to find out what is going on and what should be done about it. (456 words)1.According to Dr. Carlton, ocean organism‟s are_______.A.being moved to new environmentsB.destroying the planetC.succumbing to the zebra musselD.developing alien characteristics2.Oceanographers海洋学家are concerned because_________.A.their knowledge of this phenomenon is limitedB.they believe the oceans are dyingC.they fear an invasion from outer-spaceD.they have identified thousands of alien webs3.According to marine ecologists, transplanted marinespecies____________.A.may upset the ecosystems of coastal watersB.are all compatible with one anotherC.can only survive in their home watersD.sometimes disrupt shipping lanes4.The identified cause of the problem is_______.A.the rapidity with which larvae matureB. a common practice of the shipping industryC. a centuries old speciesD.the world wide movement of ocean currents5.The article suggests that a solution to the problem__________.A.is unlikely to be identifiedB.must precede further researchC.is hypothetically假设地，假想地easyD.will limit global shippingText BNew …Endangered‟ List Targets Many US RiversIt is hard to think of a major natural resource or pollution issue in North America today that does not affect rivers.Farm chemical runoff残渣, industrial waste, urban storm sewers, sewage treatment, mining, logging, grazing放牧,military bases, residential and business development, hydropower水力发电,loss of wetlands. The list goes on.Legislation like the Clean Water Act and Wild and Scenic Rivers Act have provided some protection, but threats continue.The Environmental Protection Agency (EPA) reported yesterday that an assessment of 642,000 miles of rivers and streams showed 34 percent in less than good condition. In a major study of the Clean Water Act, the Natural Resources Defense Council last fall reported that poison runoff impairs损害more than 125,000 miles of rivers.More recently, the NRDC and Izaak Walton League warned that pollution and loss of wetlands—made worse by last year’s flooding—is degrading恶化the Mississippi River ecosystem.On Tuesday, the conservation group保护组织American Rivers issued its annual list of 10 ―endangered‖ and 20 ―threatened‖ rivers in 32 states, the District of Colombia, and Canada.At the top of the list is the Clarks Fork of the Yellowstone River, whereCanadian mining firms plan to build a 74-acre英亩reservoir水库，蓄水池as part of a gold mine less than three miles from Yellowstone National Park. The reservoir would hold the runoff from the sulfuric acid 硫酸used to extract gold from crushed rock.―In the event this tailings pond failed, the impact to th e greater Yellowstone ecosystem would be cataclysmic大变动的，灾难性的and the damage irreversible不可逆转的.‖ Sen. Max Baucus of Montana, chairman of the Environment and Public Works Committee, wrote to Noranda Minerals Inc., an owner of the ― New World Mine‖.Last fall, an EPA official expressed concern about the mine and its potential impact, especially the plastic-lined storage reservoir. ― I am unaware of any studies evaluating how a tailings pond尾矿池，残渣池could be maintained to ensure its structural integrity forev er,‖ said Stephen Hoffman, chief of the EPA’s Mining Waste Section. ―It is my opinion that underwater disposal of tailings at New World may present a potentially significant threat to human health and the environment.‖The results of an environmental-impact statement, now being drafted by the Forest Service and Montana Department of State Lands, could determine the mine’s future…In its recent proposal to reauthorize the Clean Water Act, the Clinton administration noted ―dramatically improved water quality since 1972,‖ when the act was passed. But it also reported that 30 percent of riverscontinue to be degraded, mainly by silt泥沙and nutrients from farm and urban runoff, combined sewer overflows, and municipal sewage城市污水. Bottom sediments沉积物are contaminated污染in more than 1,000 waterways, the administration reported in releasing its proposal in January. Between 60 and 80 percent of riparian corridors (riverbank lands) have been degraded.As with endangered species and their habitats in forests and deserts, the complexity of ecosystems is seen in rivers and the effects of development----beyond the obvious threats of industrial pollution, municipal waste, and in-stream diversions改道to slake消除the thirst of new communities in dry regions like the Southwes t…While there are many political hurdles障碍ahead, reauthorization of the Clean Water Act this year holds promise for US rivers. Rep. Norm Mineta of California, who chairs the House Committee overseeing the bill, calls it ―probably the most important env ironmental legislation this Congress will enact.‖ (553 words)6.According to the passage, the Clean Water Act______.A.has been ineffectiveB.will definitely be renewedC.has never been evaluatedD.was enacted some 30 years ago7.“Endangered” rivers are _________.A.catalogued annuallyB.less polluted than ―threatened rivers‖C.caused by floodingD.adjacent to large cities8.The “cataclysmic” event referred to in paragraph eight would be__________.A. fortuitous偶然的，意外的B. adventitious外加的，偶然的C. catastrophicD. precarious不稳定的，危险的9. The owners of the New World Mine appear to be______.A. ecologically aware of the impact of miningB. determined to construct a safe tailings pondC. indifferent to the concerns voiced by the EPAD. willing to relocate operations10. The passage conveys the impression that_______.A. Canadians are disinterested in natural resourcesB. private and public environmental groups aboundC. river banks are erodingD. the majority of US rivers are in poor conditionText CA classic series of experiments to determine the effects ofoverpopulation on communities of rats was reported in February of 1962 in an article in Scientific American. The experiments were conducted by a psychologist, John B. Calhoun and his associates. In each of these experiments, an equal number of male and female adult rats were placed in an enclosure and given an adequate supply of food, water, and other necessities. The rat populations were allowed to increase. Calhoun knew from experience approximately how many rats could live in the enclosures without experiencing stress due to overcrowding. He allowed the population to increase to approximately twice this number. Then he stabilized the population by removing offspring that were not dependent on their mothers. He and his associates then carefully observed and recorded behavior in these overpopulated communities. At the end of their experiments, Calhoun and his associates were able to conclude that overcrowding causes a breakdown in the normal social relationships among rats, a kind of social disease. The rats in the experiments did not follow the same patterns of behavior as rats would in a community without overcrowding.The females in the rat population were the most seriously affected by the high population density: They showed deviant异常的maternal behavior; they did not behave as mother rats normally do. In fact, many of the pups幼兽，幼崽, as rat babies are called, died as a result of poor maternal care. For example, mothers sometimes abandoned their pups,and, without their mothers' care, the pups died. Under normal conditions, a mother rat would not leave her pups alone to die. However, the experiments verified that in overpopulated communities, mother rats do not behave normally. Their behavior may be considered pathologically 病理上，病理学地diseased.The dominant males in the rat population were the least affected by overpopulation. Each of these strong males claimed an area of the enclosure as his own. Therefore, these individuals did not experience the overcrowding in the same way as the other rats did. The fact that the dominant males had adequate space in which to live may explain why they were not as seriously affected by overpopulation as the other rats. However, dominant males did behave pathologically at times. Their antisocial behavior consisted of attacks on weaker male,female, and immature rats. This deviant behavior showed that even though the dominant males had enough living space, they too were affected by the general overcrowding in the enclosure.Non-dominant males in the experimental rat communities also exhibited deviant social behavior. Some withdrew completely; they moved very little and ate and drank at times when the other rats were sleeping in order to avoid contact with them. Other non-dominant males were hyperactive; they were much more active than is normal, chasing other rats and fighting each other. This segment of the rat population, likeall the other parts, was affected by the overpopulation.The behavior of the non-dominant males and of the other components of the rat population has parallels in human behavior. People in densely populated areas exhibit deviant behavior similar to that of the rats in Calhoun's experiments. In large urban areas such as New York City, London, Mexican City, and Cairo, there are abandoned children. There are cruel, powerful individuals, both men and women. There are also people who withdraw and people who become hyperactive. The quantity of other forms of social pathology such as murder, rape, and robbery also frequently occur in densely populated human communities. Is the principal cause of these disorders overpopulation? Calhoun’s experiments suggest that it might be. In any case, social scientists and city planners have been influenced by the results of this series of experiments.11. Paragraph l is organized according to__________.A. reasonsB. descriptionC. examplesD. definition12．Calhoun stabilized the rat population_________.A. when it was double the number that could live in the enclosure without stressB. by removing young ratsC. at a constant number of adult rats in the enclosureD. all of the above are correct13.W hich of the following inferences CANNOT be made from theinformation inPara. 1?A. Calhoun's experiment is still considered important today.B. Overpopulation causes pathological behavior in rat populations.C. Stress does not occur in rat communities unless there is overcrowding.D. Calhoun had experimented with rats before.14. Which of the following behavior didn‟t happen in this experiment?A. All the male rats exhibited pathological behavior.B. Mother rats abandoned their pups.C. Female rats showed deviant maternal behavior.D. Mother rats left their rat babies alone.15. The main idea of the paragraph three is that __________.A. dominant males had adequate living spaceB. dominant males were not as seriously affected by overcrowding as the otherratsC. dominant males attacked weaker ratsD. the strongest males are always able to adapt to bad conditionsText DThe first mention of slavery in the statutes法令，法规of the English colonies of North America does not occur until after 1660—some forty years after the importation of the first Black people. Lest we think that existed in fact before it did in law, Oscar and Mary Handlin assure us, that the status of B lack people down to the 1660’s was that of servants. A critique批判of the Handlins’ interpretation of why legal slavery did not appear until the 1660’s suggests that assumptions about the relation between slavery and racial prejudice should be reexamined, and that explanation for the different treatment of Black slaves in North and South America should be expanded.The Handlins explain the appearance of legal slavery by arguing that, during the 1660’s, the position of white servants was improving relative to that of black servants. Thus, the Handlins contend, Black and White servants, heretofore treated alike, each attained a different status. There are, however, important objections to this argument. First, the Handlins cannot adequately demonstrate that t he White servant’s position was improving, during and after the 1660’s; several acts of the Maryland and Virginia legislatures indicate otherwise. Another flaw in the Handlins’ interpretation is their assumption that prior to the establishment of legal slavery there was no discrimination against Black people. It is true that before the 1660’s Black people were rarely called slaves. But this shouldnot overshadow evidence from the 1630’s on that points to racial discrimination without using the term slavery. Such discrimination sometimes stopped short of lifetime servitude or inherited status—the two attributes of true slavery—yet in other cases it included both. The Handlins’ argument excludes the real possibility that Black people in the English colonies were never treated as the equals of White people.The possibility has important ramifications后果，影响.If from the outset Black people were discriminated against, then legal slavery should be viewed as a reflection and an extension of racial prejudice rather than, as many historians including the Handlins have argued, the cause of prejudice. In addition, the existence of discrimination before the advent of legal slavery offers a further explanation for the harsher treatment of Black slaves in North than in South America. Freyre and Tannenbaum have rightly argued that the lack of certain traditions in North America—such as a Roman conception of slavery and a Roman Catholic emphasis on equality— explains why the treatment of Black slaves was more severe there than in the Spanish and Portuguese colonies of South America. But this cannot be the whole explanation since it is merely negative, based only on a lack of something. A more compelling令人信服的explanation is that the early and sometimes extreme racial discrimination in the English colonies helped determine the particular nature of the slavery that followed. (462 words)16. Which of the following is the most logical inference to be drawn from the passage about the effects of “several acts of the Maryland and Virginia legislatures” (Para.2) passed during and after the 1660‟s?A. The acts negatively affected the pre-1660’s position of Black as wellas of White servants.B. The acts had the effect of impairing rather than improving theposition of White servants relative to what it had been before the 1660’s.C. The acts had a different effect on the position of white servants thandid many of the acts passed during this time by the legislatures of other colonies.D. The acts, at the very least, caused the position of White servants toremain no better than it had been before the 1660’s.17. With which of the following statements regarding the status ofBlack people in the English colonies of North America before the 1660‟s would the author be LEAST likely to agree?A. Although black people were not legally considered to be slaves,they were often called slaves.B. Although subject to some discrimination, black people had a higherlegal status than they did after the 1660’s.C. Although sometimes subject to lifetime servitude, black peoplewere not legally considered to be slaves.D. Although often not treated the same as White people, black people,like many white people, possessed the legal status of servants.18. According to the passage, the Handlins have argued which of thefollowing about the relationship between racial prejudice and the institution of legal slavery in the English colonies of North America?A. Racial prejudice and the institution of slavery arose simultaneously.B. Racial prejudice most often the form of the imposition of inheritedstatus, one of the attributes of slavery.C. The source of racial prejudice was the institution of slavery.D. Because of the influence of the Roman Catholic Church, racialprejudice sometimes did not result in slavery.19. The passage suggests that the existence of a Roman conception ofslavery in Spanish and Portuguese colonies had the effect of _________.A. extending rather than causing racial prejudice in these coloniesB. hastening the legalization of slavery in these colonies.C. mitigating some of the conditions of slavery for black people in these coloniesD. delaying the introduction of slavery into the English colonies20. The author considers the explanation put forward by Freyre andTannenbaum for the treatment accorded B lack slaves in the English colonies of North America to be _____________.A. ambitious but misguidedB. valid有根据的but limitedC. popular but suspectD. anachronistic过时的，时代错误的and controversialUNIT 2Text AThe sea lay like an unbroken mirror all around the pine-girt, lonely shores of Orr’s Island. Tall, kingly spruce s wore their regal王室的crowns of cones high in air, sparkling with diamonds of clear exuded gum流出的树胶; vast old hemlocks铁杉of primeval原始的growth stood darkling in their forest shadows, their branches hung with long hoary moss久远的青苔;while feathery larches羽毛般的落叶松,turned to brilliant gold by autumn frosts, lighted up the darker shadows of the evergreens. It was one of those hazy朦胧的, calm, dissolving days of Indian summer, when everything is so quiet that the fainest kiss of the wave on the beach can be heard, and white clouds seem to faint into the blue of the sky, and soft swathing一长条bands of violet vapor make all earth look dreamy, and give to the sharp, clear-cut outlines of the northern landscape all those mysteries of light and shade which impart such tenderness to Italian scenery.The funeral was over,--- the tread鞋底的花纹/ 踏of many feet, bearing the heavy burden of two broken lives, had been to the lonely graveyard, and had come back again,--- each footstep lighter and more unconstrained不受拘束的as each one went his way from the great old tragedy of Death to the common cheerful of Life.The solemn black clock stood swaying with its eternal ―tick-tock, tick-tock,‖ in the kitchen of the brown house on Orr’s Island. There was there that sense of a stillness that can be felt,---such as settles down on a dwelling住处when any of its inmates have passed through its doors for the last time, to go whence they shall not return. The best room was shut up and darkened, with only so much light as could fall through a little heart-shaped hole in the window-shutter,---for except on solemn visits, or prayer-meetings or weddings, or funerals, that room formed no part of the daily family scenery.The kitchen was clean and ample, hearth灶台, and oven on one side, and rows of old-fashioned splint-bottomed chairs against the wall. A table scoured to snowy whiteness, and a little work-stand whereon lay the Bible, the Missionary Herald, and the Weekly Christian Mirror, before named, formed the principal furniture. One feature, however, must not be forgotten, ---a great sea-chest水手用的储物箱,which had been the companion of Zephaniah through all the countries of the earth. Old, and battered破旧的，磨损的, and unsightly难看的it looked, yet report said that there was good store within which men for the most part respect more than anything else; and, indeed it proved often when a deed of grace was to be done--- when a woman was suddenly made a widow in a coast gale大风，狂风, or a fishing-smack小渔船was run down in the fogs off the banks, leaving in some neighboring cottage a family of orphans,---in all such cases, the opening of this sea-chest was an event of good omen 预兆to the bereaved丧亲者;for Zephaniah had a large heart and a large hand, and was apt有…的倾向to take it out full of silver dollars when once it went in. So the ark of the covenant约柜could not have been looked on with more reverence崇敬than the neighbours usually showed to Captain Pennel’s sea-chest.1. The author describes Orr‟s Island in a(n)______way.A.emotionally appealing, imaginativeB.rational, logically preciseC.factually detailed, objectiveD.vague, uncertain2.According to the passage, the “best room”_____.A.has its many windows boarded upB.has had the furniture removedC.is used only on formal and ceremonious occasionsD.is the busiest room in the house3.From the description of the kitchen we can infer that thehouse belongs to people who_____.A.never have guestsB.like modern appliancesC.are probably religiousD.dislike housework4.The passage implies that_______.A.few people attended the funeralB.fishing is a secure vocationC.the island is densely populatedD.the house belonged to the deceased5.From the description of Zephaniah we can see thathe_________.A.was physically a very big manB.preferred the lonely life of a sailorC.always stayed at homeD.was frugal and saved a lotText BBasic to any understanding of Canada in the 20 years after the Second World War is the country' s impressive population growth. For every three Canadians in 1945, there were over five in 1966. In September 1966 Canada's population passed the 20 million mark. Most of this surging growth came from natural increase. The depression of the 1930s and the war had held back marriages, and the catching-up process began after 1945. The baby boom continued through the decade of the 1950s, producing a population increase of nearly fifteen percent in the five years from 1951 to 1956. This rate of increase had been exceeded only once before in Canada's history, in the decade before 1911 when the prairies were being settled. Undoubtedly, the good economic conditions of the 1950s supported a growth in the population, but the expansion also derived from a trend toward earlier marriages and an increase in the average size of families; In 1957 the Canadian birth rate stood at 28 per thousand, one of the highest in the world. After the peak year of 1957, thebirth rate in Canada began to decline. It continued falling until in 1966 it stood at the lowest level in 25 years. Partly this decline reflected the low level of births during the depression and the war, but it was also caused by changes in Canadian society. Young people were staying at school longer, more women were working; young married couples were buying automobiles or houses before starting families; rising living standards were cutting down the size of families. It appeared that Canada was once more falling in step with the trend toward smaller families that had occurred all through theWestern world since the time of the Industrial Revolution. Although the growth in Canada’s population had slowed down by 1966 (the cent), another increase in the first half of the 1960s was only nine percent), another large population wave was coming over the horizon. It would be composed of the children of the children who were born during the period of the high birth rate prior to 1957.6. What does the passage mainly discuss?A. Educational changes in Canadian society.B. Canada during the Second World War.C. Population trends in postwar Canada.D. Standards of living in Canada.7. According to the passage, when did Canada's baby boom begin?A. In the decade after 1911.B. After 1945.C. During the depression of the 1930s.D. In 1966.8. The author suggests that in Canada during the 1950s____________.A. the urban population decreased rapidlyB. fewer people marriedC. economic conditions were poorD. the birth rate was very high9. When was the birth rate in Canada at its lowest postwar level?A. 1966.B. 1957.C. 1956.D. 1951.10. The author mentions all of the following as causes of declines inpopulation growth after 1957 EXCEPT_________________.A. people being better educatedB. people getting married earlierC. better standards of livingD. couples buying houses11.I t can be inferred from the passage that before the IndustrialRevolution_______________.A. families were largerB. population statistics were unreliableC. the population grew steadilyD. economic conditions were badText CI was just a boy when my father brought me to Harlem for the first time, almost 50 years ago. We stayed at the hotel Theresa, a grand brick structure at 125th Street and Seventh avenue. Once, in the hotel restaurant, my father pointed out Joe Louis. He even got Mr. Brown, the hotel manager, to introduce me to him, a bit punchy强力的but still champ焦急as fast as I was concerned.Much has changed since then. Business and real estate are booming. Some say a new renaissance is under way. Others decry责难what they see as outside forces running roughshod肆意践踏over the old Harlem. New York meant Harlem to me, and as a young man I visited it whenever I could. But many of my old haunts are gone. The Theresa shut down in 1966. National chains that once ignored Harlem now anticipate yuppie money and want pieces of this prime Manhattan real estate. So here I am on a hot August afternoon, sitting in a Starbucks that two years ago opened a block away from the Theresa, snatching抓取，攫取at memories between sips of high-priced coffee. I am about to open up a piece of the old Harlem---the New York Amsterdam News---when a tourist。
最相似近邻法-概述说明以及解释
最相似近邻法-概述说明以及解释1.引言1.1 概述最相似近邻法是一种常用的机器学习算法，也被称为k近邻算法。
它是一种基于实例的学习方法，通过计算待预测样本与训练集中样本的相似度，来进行分类或回归预测。
该算法的核心思想是利用输入样本与训练集中已有样本的特征信息进行对比，找出与输入样本最相似的k个样本，并根据它们的标签信息来对输入样本进行分类或回归预测。
这种基于相似度的方法能够很好地捕捉样本之间的关系，适用于各种不规则分布的数据集。
最相似近邻法在实际应用中具有广泛的适用性，包括图像识别、推荐系统、医学诊断等领域。
尽管该算法存在一定的计算复杂度和需要大量存储空间的缺点，但其简单直观的原理和良好的泛化能力使其成为机器学习领域中不可或缺的一部分。
1.2 文章结构本文分为引言、正文和结论三个部分。
在引言部分，将对最相似近邻法进行概述，并介绍文章的结构和目的。
在正文部分，将详细介绍什么是最相似近邻法，以及它在不同应用领域的具体应用情况。
同时，将梳理最相似近邻法的优缺点，为读者提供全面的了解。
最后，在结论部分，将总结本文的主要内容，展望最相似近邻法的未来发展前景，并给出结论性的观点和建议。
整个文章将通过逻辑清晰的结构，带领读者深入理解和认识最相似近邻法的重要性和应用。
1.3 目的最相似近邻法是一种常用的机器学习算法，其主要目的是通过比较不同数据点之间的相似度，找出与目标数据点最相似的邻居。
通过这种方法，我们可以实现数据分类、推荐系统、图像识别等多种应用。
本文旨在深入探讨最相似近邻法的原理、应用领域以及优缺点，希望读者能更全面地了解这一算法，并在实际应用中取得更好的效果。
同时，我们也将展望最相似近邻法在未来的发展前景，为读者提供对未来研究方向的参考。
通过本文的阐述，希望读者能够更深入地理解最相似近邻法，为其在实际应用中提供更好的指导。
2.正文2.1 什么是最相似近邻法最相似近邻法是一种常用的机器学习算法，它通过计算数据样本之间的相似度来进行分类或回归预测。
计量经济学中英文词汇对照
Controlled experiments Conventional depth Convolution Corrected factor Corrected mean Correction coefficient Correctness Correlation coefficient Correlation index Correspondence Counting Counts Covaห้องสมุดไป่ตู้iance Covariant Cox Regression Criteria for fitting Criteria of least squares Critical ratio Critical region Critical value
Asymmetric distribution Asymptotic bias Asymptotic efficiency Asymptotic variance Attributable risk Attribute data Attribution Autocorrelation Autocorrelation of residuals Average Average confidence interval length Average growth rate BBB Bar chart Bar graph Base period Bayes' theorem Bell-shaped curve Bernoulli distribution Best-trim estimator Bias Binary logistic regression Binomial distribution Bisquare Bivariate Correlate Bivariate normal distribution Bivariate normal population Biweight interval Biweight M-estimator Block BMDP(Biomedical computer programs) Boxplots Breakdown bound CCC Canonical correlation Caption Case-control study Categorical variable Catenary Cauchy distribution Cause-and-effect relationship Cell Censoring
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Viola-Jones, 2001
Spatial pyramid matching, 2006
Deformable Parts-based Model, 2008
Caltech-4, 1999
Caltech - 101, 2004
Caltech - 256, 2007
ImageNet, 2009-2011
challengVeiesw?point
baHerring Gull
Different class, very similar appearance
Herring Gull
10
Existing methods on this Problem
California Gull
Reference image: California gull
California Gull
California Gull
California Gull
Can existingDaifpfeprernot apocshees adeDqiffuearetnet ly addreDsifsfetrehnetse
Combining Randomization and Discrimination for Fine-grained Image
Categorization (CVPR 2011)
Bangpeng Yao*, Aditya Khosla*, and Li Fei-Fei
Computer Science Department, Stanford University
Caltech-4, 1999
Caltech - 101, 2004
Caltech - 256, 2007
ImageNet, 2009-2011
6
Fine-Grained Categorization: Potential Applications
We are looking for a red Camry
Herring Gull
12 [Grauman & Darrell, 2005, Lazebnik et al, 2006]
Existing methods on this Problem
California Gull
California Gull
Herring Gull
13 [Grauman & Darrell, 2005, Lazebnik et al, 2006]
paoriesoendoibulse…!
Fine-Grained Oracle Fine-Grained Oracle Fine-Grained Oracle
2
From Base-level to Fine-grained Categorization
Mammals
Cats
Dogs
Cows
Base-level Categorization
8
Outline
• Fine-grained Image Categorization • Our Method • Dataset & Experiments • ImageNet Datasets • Conclusion
9
Fine-grained Categorization is Challenging
Our Intuition: What do humans do?
California Gull
California Gull
Herring Gull
Our goal: Find image regions
14
Our Intuition: What do humans do?
Pugs
Boxer
Mastiff
[Rosch, 1979]
Fine-grained Categorization
3
Subordinate Categorization
• Children learn to identify base-level categories before subordinate categories
5
Recently Emerging Fine-Grained Datasets
Caltech-UCSD Birds 200
Action Classification (PASCAL VOC, PPMI, …)
CUB-200, 2010
Action Classification, 2010
ImageNet Winter Release, 2011
Robots handling Assisting humans in
Fine-grained
tools/cooking fine-discrimination tracking/surveillance
7
Outline
• Fine-grained Image Categorization • Our Method • Dataset & Experiments • ImageNet Datasets • Conclusion
(* - indicates equal contribution)
{bangpeng,aditya86,feifeili}@
1
Species: Amanita Muscaria
Species: Red-capped Scaber
Hmmm, I wonder if thetsheismsunsahkreoiosms
California Gull
Herring Gull
High Weights Low weights
11 [Grauman & Darrell, 2005, Lazebnik et al, 2006]
Existing methods on this Problem
California Gull
California Gull
Stilettos!
Flats! Pumps! Sling backs!
Platforms! Mary Janes! Peep toes!
Shoes!
[Johnson & Eilers, 1998]
4
Computer vision has followed a similar trajectory!