Adaptive-feedrate Interpolation for Parametric Curves with a

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基于遗传算法的递归MTI自适应滤波器的设计

信息疼术2018卑第7期文章编号：1009 -2552(2018)07 -0090 -04 DOI：10. 13274/j. cn k i. h d z j. 2018. 07. 021基于遗传算法的递归M T I自适应滤波器的设计殷万君\金炜东2(1.四川信息职业技术学院，四川广元628040; 2.西南交通大学，成都610031)摘要：针对自适应滤波器在F P G A上实现结构灵活性的特点，文中提出了一种基于遗传算法的递归M T I自适应滤波器的设计方法。

根据遗传算法的特点，结合滤波器的性能指标，阐述了设计思想，通过遗传算法实现了自适应滤波器的权系数寻优，在系数寻优中采用了创新的适应度函数和惩罚函数，通过场景仿真，验证了文中所提算法的实用性和有效性。

关键词：遗传算法；递归M T I;自适应滤波器；设计中图分类号：T N957.52 文献标识码：ADesign of recursive MTI adaptive filter based on genetic algorithmYIN Wan-jun1，JIN Wei-dong2(1. Sichuan Inform ation Technology College，Guangyuan 628040，Sichuan Province，China；2. Southwest Jiaotong University，Chengdu 610031，China)Abstract ：In order to realize the fle x ib ility o f adaptive filte r in F P G A，a design m ethod o f recursive M T I adaptive filte r based on genetic a lgo rithm is proposed in th is p a p e r.A c co rd in g to the cha racteristics o f genetic a lg o rith m，com bined w ith the perform ance o f the f ilt e r，it expounds the design id e a s，through the genetic a lgo rithm to achieve the rig h t of the adaptive filte r co e fficie n t o p tim iz a tio n，op tim iza tio n of the coe fficien ts in the in no vation o f the fitness fu n c tio n and pe na lty fu n c tio n.Through s im u la tio n，it verifies the p ra c tic a lity and effectiveness o f the proposed a lg o rith m.Key words：genetic a lg o rith m；recursive M T I；adaptive f ilt e r；design0引言自适应滤波器使用广泛，可以由训练样本根据某种算法去调节加权系数，使实际输出与理想输出的均方差达到最小。

变时滞反馈控制的混合中立型随机延迟微分方程的指数稳定性

第50卷第6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.62023引用格式:刘琪,兰光强.变时滞反馈控制的混合中立型随机延迟微分方程的指数稳定性[J].北京化工大学学报(自然科学版),2023,50(6):105-111.LIU Qi,LAN GuangQiang.Exponential stability of hybrid neutral stochastic differential delay equations with time⁃depend⁃ent delay feedback control[J].Journal of Beijing University of Chemical Technology (Natural Science),2023,50(6):105-111.变时滞反馈控制的混合中立型随机延迟微分方程的指数稳定性刘　琪　兰光强*(北京化工大学数理学院,北京　100029)摘　要:研究了变时滞反馈控制的混合中立型随机延迟微分方程(HNSDDEs)的指数稳定性㊂采用函数方法设置合适的变时滞反馈控制函数,得到了该系统的指数稳定性㊂对比已有的研究成果,本文的主要贡献是在变时滞反馈控制下对HNSDDEs 的指数稳定性作了进一步研究㊂最后,给出一个例子证明了结论的有效性㊂关键词:变时滞;混合中立型随机延迟微分方程(HNSDDEs);反馈控制;指数稳定性中图分类号:O211.6 DOI :10.13543/j.bhxbzr.2023.06.013收稿日期:2022-09-05基金项目:北京市自然科学基金(1192013)第一作者:女,1998年生,硕士生*通信联系人E⁃mail:langq@引　言带有变时滞反馈控制的混合中立型随机延迟微分方程(HNSDDEs)常被用于系统未来的建模,目前已经被广泛应用于种群生态㊁神经网络以及激光器动力学等领域㊂对于随机系统突然性的结构变化,常采用连续时间马氏链来描述,带有马氏链的随机延迟微分方程即为混合随机延迟微分方程㊂文献[1]具体研究了混合随机延迟微分方程,文献[2-4]则进一步考虑了其稳定性及有界性,文献[5-7]又扩展到了带中立项的混合随机延迟微分方程的稳定性研究㊂然而并非所有系统都是稳定的,因此设计一个合适的反馈控制使不稳定的系统变得稳定很有意义㊂相应地,文献[8-11]研究了系统稳定化问题㊂其中文献[8]研究了常时滞反馈控制的高阶非线性混合随机时滞微分方程的指数稳定性,文献[9]是在文献[10]的基础上进一步研究了变时滞反馈控制的HNSDDEs 的L p 渐进稳定性和H ∞稳定性㊂本文采用Lyapunov 函数方法,进一步研究了变时滞反馈控制下的HNSDDEs 的指数稳定性㊂文献[8]研究了常时滞反馈控制下的混合随机微分延迟方程的指数稳定性,其所涉及的时滞均为常量,本文进一步将常时滞推广到了函数时滞,并且将受控方程推广到了带有中立项的混合随机延迟微分方程,其难点在于找到时滞δ(t )的上界和利用引理2处理中立项㊂文献[9]研究了变时滞反馈控制的具有时变延迟的高度非线性HNSDDEs 的L p 渐近稳定性和H ∞稳定性,但缺少指数稳定性,本文则是通过进一步找到更合适的反馈函数确定了方程的收敛速度,即指数稳定性㊂1　基本假设与模型描述设(Ω,F ,{F t }t ≥0,P )是一个带有σ流(满足通常条件)的完备概率空间,{B (t )}t ≥0是定义在其上的m 维布朗运动,{r (t )}t ≥0是右连马氏链且独立于{B (t )}t ≥0,S ={1,2, ,N }是其状态空间,Γ=(γij )N ×N 是其生成算子㊂考虑变时滞反馈控制HNSDDEd ^x(t )=f (x (t ),x (t -τ(t )),t ,r (t ))d t +g (x (t ),x (t -τ(t )),t ,r (t ))d B (t ),t ≥0(1)其中^x(t )=x (t )-N (x (t -τ(t )),t ,r (t )),且初值满足{x(θ):-τ≤θ≤0}=φ∈C([-τ,0];n)r(0)=r0∈S(2)其中f,g,N均为Borel可测函数,并且满足f:n×n×+×S→ng:n×n×+×S→n×mN:n×+×S→n加上反馈控制函数u之后系统变为d^x(t)=[f(x(t),x(t-τ(t)),t,r(t))+u(x(t-δ(t)),t,r(t))]d t+g(x(t),x(t-τ(t)),t,r(t))㊃d B(t),t≥0(3)其中0≤δ(t)≤δ≤τ,0≤τ(t)≤τ㊂假设f(0,0,t,i)=N(0,t,i)≡0,g(0,0,t,i)≡0V(x,t,i)∈C2,1(n×+×S;+)为方便起见,简记^x=x-N(y,t,i)㊂对V(x,t,i)∈C2,1(n×+×S;+)定义如下算子LL V(x,y,t,i)=V t(^x,t,i)+V T x(^x,t,i)f(x,y,t, i)+12trace[g T(x,y,t,i)V xx(^x,t,i)g(x,y,t,i)]+∑j∈sγij V(^x,t,j)(4)为得到本文主要结论,提出以下假设㊂假设1　对任意l>0,存在K l>0,使得对任意i∈S,t∈+,且|x|∨|x|∨|y|∨|y|≤l,满足|f(x,y,t,i)-f(x,y,t,i)|∨|g(x,y,t,i)-g(x,y,t,i)|≤Kl(|x-x|+|y-y|)(5)假设2　存在K>0,m1>1,m2≥1,使得对∀x, y∈n,i∈S,t∈+,有|f(x,y,t,i)|≤K(|x|m1+|y|m1+1)|g(x,y,t,i)|≤K(|x|m2+|y|m2+1)(6)假设3　系统(3)中的时滞函数τ:+→[0,τ]满足τ′(t)=dτ(t)d t≤τ<1,t≥0(7)系统(3)反馈控制函数中的δ:+→[0,δ]满足δ′(t)=dδ(t)d t≤δ<1,t≥0(8)假设4　存在κ∈(0,1)使得对∀x,y∈n,i∈S,t∈+,有|N(x,t,i)-N(y,t,i)|≤κ(1-τ)|x-y|(9)并且N(0,t,i)≡0㊂假设5　存在常数c1,c2,c3,c4>0,c2>c3+c4和函数V∈C2,1(n×+×S;+),U1,U2∈C(×[-τ,+∞];+),使得对∀x,y∈n,i∈S,t∈+,有U1(x,t)≤V(x,t,i)≤U2(x,t)L V(x,y,t,i)+V x(x-N(y),t,i)u(z,t,i)≤c1-c2U2(x,t)+c3(1-τ)U2(y,t-τ(t))+c4(1-δ)U2(z,t-δ(t))(10)由文献[7]可得如下引理㊂引理1　设假设1~4成立,且假设5对于U1(x,t)=|x|w成立,那么系统(3)有唯一的全局解,并且满足sup-τ≤t<∞E|x(t)|w<∞,w≥2(m1∨m2)由文献[5]中引理2.2以及式(9)可得引理2　若p≥1,则[1-κ(1-τ)]p-1[|x|p-κ(1-τ)|y|p]≤|x-N(y,t,i)|p≤[1+κ(1-τ)]p-1[|x|p+κ(1-τ)|y|p](11) 2　主要结论与证明定义片段过程x(t)={x(t+s):-2τ≤s≤0,0≤t≤2τ}同理定义r(t),且令r(s)=r(0),s∈[-2τ,0)x(s)=φ(-τ),s∈[-2τ,-τ{)令U∈C2,1(n×+×S;+)且满足lim|x|→∞inf(t,i)∈+×SU(x,t,i[])=∞对于t∈+,定义V(x(t),t,r(t))=U(^x(t),t,r(t))+ρ∫0-δ∫t t+s J(v)㊃d v d s(12)其中ρ>0,且J(t):=δ|u(x(t-δ(t)),t,r(t))+f(x(t),x(t-τ(t)),t,r(t))|2+|g(x(t),x(t-τ(t)),t,r(t))|2对于x,y∈n,i∈S,s∈[-2τ,0),设f(x,y,s,i)≡f(x,y,0,i)g(x,y,s,i)≡g(x,y,0,i)u(z,s,i)≡u(z,0,i)由伊藤公式可得d U(^x(t),t,r(t))=[U t(^x(t),t,r(t))+ U T x(^x(t),t,r(t))(f(x(t),x(t-τ(t)),t,r(t))+ u(x(t-δ(t)),t,r(t)))+∑j∈Sγj,r(t)U(^x(t),t,j)+ 12trace[g T(x(t),x(t-τ(t)),t,r(t))U xx(^x(t),t,㊃601㊃北京化工大学学报(自然科学版) 2023年r(t))g(x(t),x(t-τ(t)),t,r(t))]d t+d B(t)(13)其中,B(t)是局部鞅,并且B(0)=0㊂整理式(13)得d U(^x(t),t,r(t))=l U(x(t),x(t-τ(t)),t, r(t))d t+U T x(^x(t),t,r(t))[u(x(t-δ(t)),t, r(t))-u(x(t),t,r(t))]d t+d B(t)其中,l U(x(t),x(t-τ(t)),t,r(t))=Ut(^x(t),t, r(t))+U T x(^x(t),t,r(t))[f(x(t),x(t-τ(t)),t, r(t))+u(x(t),t,r(t))]+∑j∈Sγj,r(t)U(^x(t),t,j)+ 12trace[g T(x(t),x(t-τ(t)),t,r(t))U xx(^x(t),t, r(t))g(x(t),x(t-τ(t)),t,r(t))]进而易得以下结论㊂引理3　V(x(t),t,r(t)),t≥0是伊藤过程,且有d V(x(t),t,r(t))=d B(t)+L V(x(t),t,r(t))㊃d t其中,L V(x(t),t,r(t))=l U(x(t),x(t-τ(t)),t, r(t))+ρδJ(t)-ρ∫t t-δJ(v)d v+U T x(^x(t),t,r(t))㊃[u(x(t-δ(t)),t,r(t))-u(x(t),t,r(t))](14)假设6　对于函数u:n×S×+→n,存在实数a i,a i,正数d i,d i和非负数b i,b i,e i,e i(i∈S),对于任意q1>1,p>2有x T[f(x,y,t,i)+u(x,t,i)]+12|g(x,y,t,i)|2≤a i|x|2+b i|y|2-d i|x|p+e i|y|px T[f(x,y,t,i)+u(x,t,i)]+q12|g(x,y,t,i)|2≤a i|x|2+b i|y|2-d i|x|p+e i|y|p且A1:=-2diag(a1,a2, ,a N)-ΓA2:=-(q1+1)diag(a1,a2, ,a N)-Γ是非奇异M矩阵(具体定义可参考文献[1]中的2.6部分),并有1>γ1,γ2>γ3,1>γ4,γ5>γ6(θ1,θ2, ,θN)T=A-11(1, ,1)T(θ1,θ2, ,θN)T=A-12(1, ,1)Tγ1=max i∈S2θi b i,γ2=min i∈S2θi d iγ3=max i∈S2θi e i,γ4=max i∈S(q1+1)θi b iγ5=min i∈S(q1+1)θi d i,γ6=max i∈S(q1+1)θi e i其中θi和θi是正数㊂需要注意的是,关于控制函数u的选取,考虑如下特殊情况x T f(x,y,t,i)+q-12|g(x,y,t,i)|2≤a(|x|2+ |y|2)-b|x|p+c|y|p其中a>0,b>c>0㊂由于|x|2,|y|2的系数均为正数,因此只能得到原方程的矩有界性,而得不到稳定性㊂此时可选取u(x,t,i)=Ax,其中矩阵A为实对称正定矩阵,且满足λmax(A)<-2a,从而x T[f(x,y,t,i)+u(x,t,i)]+q-12㊃|g(x,y,t,i)|2≤(λmax(A)+a)|x|2+a|y|2-b|x|p+c|y|p故加上控制项之后的系统指数稳定㊂假设7　存在U∈C2,1(n×+×S;+),H∈C(n;+),及常数0<α<1,0<β<λ,0<λ1,λ2,λ3,ρ1,ρ2,使得对任意的x,y∈n,i∈S,t∈+有l U(x,y,t,i)+λ1|U x(^x,t,i)|2+λ2㊃|f(x,y,t,i)|2+λ3|g(x,y,t,i)|2≤-λ|x|2+(1-τ)β|y|2-H(x)+(1-τ)αH(y)(15)其中,ρ1|x|p+q1-1≤H(x)≤ρ2(1+|x|p+q1-1)㊂假设8　存在λ4>0满足|u(x,t,i)-u(y,t,i)|≤λ4|x-y|(16)并且有u(0,t,i)=0㊂故有∀x∈n,u(x,t,i)≤λ4㊃|x|㊂定理1　令q∈[2,w),w≥2(m1∨m2)㊂若假设1~8成立,且常数满足κ(1-τ)<12δ≤λ1λ2(1-κ)(1-κ(1-τ))λ4∧2λ1λ3(1-κ)(1-κ(1-τ))λ24∧(λ-β)(1-δ)λ1(1-κ)(1-κ(1-τ))λ24则对任意初值,存在ε>0使得系统(3)的解满足lim t→∞sup1t ln(E|x(t)|q)≤-εw-q w-2(17)其中ε=ε1∧ε2∧ε3∧ε4,ε1,ε2,ε3,ε4分别是以下4个方程的根㊃701㊃第6期刘　琪等:变时滞反馈控制的混合中立型随机延迟微分方程的指数稳定性εδ+2(1-κ)(1-κ(1-τ))=1[εh 3ρ-11(1+κ(1-τ))p +q 1-2](κe ετ+1)+e ετα=1ε(h 2+h 3)(1+κ(1-τ))(1+e ετκ)+βe ετ+2ρδ2λ24eεδ1-δ+λ4κ2(1-τ)e ετ(1-τ-δ+e εδ(1-τ ))λ1(1-δ-τ)=λ2e ετκ2(1-τ)2=1特别地,当q =2时有lim t →∞sup 1tln (E |x (t )|2)≤-ε(18)即满足均方指数稳定㊂证明:证明分为两步㊂1)第一步取k 0>0足够大使得‖φ‖:=sup -τ≤s ≤0φ(s )<k 0㊂定义σk =inf {t ≥0:|x (t )≥k |}(k ≥k 0),且inf ϕ=∞㊂由引理1和文献[7],当k →∞,则σk →∞,a.s.根据假设6再定义U (^x,i )=θi |^x |2+θi |^x |q 1+1(19)由伊藤公式有e εtEV (x (t ),t ,r (t ))=V (x (0),0,r (0))+∫te εs (εV (x (s ),s ,r (s ))+L V (x (s ),s ,r (s )))d s取h 1=min i ∈Sθi ,h 2=max i ∈S θi ,h 3=max i ∈Sθi ,结合式(12)可得h 1eε(t ∧σk )E |^x(t ∧σk )|2≤V (x (0),0,r (0))+∫t ∧σk0e εs E (L V (x (s ),s ,r (s )))d s +ερJ 1(t ∧σk )+∫t ∧σke εs (εh 2E |^x(s )|2+εh 3E |^x (s )|q 1+1)d s (20)其中,J 1(t ∧σk )=E ∫t ∧σke ε(s∫0-δ∫ss +uJ (v )d v d )u ㊃d s ㊂对于式(20)中的E |^x(t ∧σk )|2结合基本不等式可得到E |x (t ∧σk )|2≤2E |^x(t ∧σk )|2+2κ2(1-τ)2E |x (t ∧σk -τ(t ∧σk ))|2(21)对于式(20)中的L V (x (t ),t ,r (t ))结合式(14)和假设7有L V (x (t ),t ,r (t ))≤-λ|x (t )|2+(1-τ)β㊃|x (t -τ(t ))|2-H (x (t ))+(1-τ)αH (x (t -τ(t )))-λ1|U x (^x(t ),t ,r (t ))|2-λ2|f (x (t ),x (t -τ(t )),t ,r (t ))|2-λ3|g (x (t ),x (t -τ(t )),t ,r (t ))|2+ρδJ (t )-ρ∫tt-δJ (v )d v +U T x (^x (t ),t ,r (t ))㊃[u (x (t -δ(t )),t ,r (t ))-u (x (t ),t ,r (t ))]由假设8运用均值不等式可以得到U T x (^x (t ),t ,r (t ))[u (x (t -δ(t )),t ,r (t ))-u (x (t ),t ,r (t ))]≤λ1|U x (^x(t ),t ,r (t ))|2+λ244λ1㊃|x (t -δ(t ))-x (t )|2定义ρ=λ242λ1(1-κ)(1-κ(1-τ)),由定理1中δ满足的不等式知2ρδ2≤λ2,ρδ≤λ3㊂再由Hölder 不等式有E |x (t -δ(t ))-x (t )|2≤2E |^x(t )-^x (t -δ(t ))|2+2E |N (x (t -τ(t )),t ,r (t ))-N (x (t -τ(t )-δ(t ),t ,r (t ))|2≤4E∫tt-δ[δ|u (x (v -δ(v )),v ,r (v ))+f (x (v ),x (v -τ(v )),v ,r (v ))|2+|g (x (v ),x (v -τ(v )),v ,r (v ))|2]d v +2κ2(1-τ)2E |x (t -τ(t ))-x (t -τ(t )-δ(t ))|2所以有E L V (x (t ),t ,r (t ))≤-λE |x (t )|2+(1-τ)㊃βE |x (t -τ(t ))|2-EH (x (t ))+(1-τ)αEH (x (t -τ(t )))+2ρδ2λ24E |x (t -δ(t ))|2(+λ24λ1-)ρ㊃E∫t t -δJ (v )d v +λ4κ2(1-τ)22λ1E |x (t -τ(t ))-x (t -τ(t )-δ(t ))|2(22)对于式(20)中的E |^x(t )|q 1+1有以下关系式E |^x(t )|q 1+1≤E |^x (t )|2+E |^x (t )|p +q 1-1(23)又由假设7有|x (t )|p +q 1-1≤ρ-11H (x (t ))(24)所以结合式(20)~(23)有12h 1e ε(t ∧σk )E |x (t ∧σk )|2≤Π1+Π2+Π3+∫t ∧σke εs (εh 2E |^x(s )|2+εh 3E |^x (s )|2+εh 3㊃E |^x(s )|p +q 1-1)d s +∫t ∧σke εs E [-λ|x (s )|2+(1-τ)㊃β|x (s -τ(s ))|2-H (x (s ))+(1-τ)αH (x (s -τ(s )))+2ρδ2λ24|x (s -δ(s ))|2+λ4κ2(1-τ)22λ1㊃|x (s -τ(s ))-x (s -τ(s )-δ(s ))|2]d s(25)其中,Π1=h 1e ε(t ∧σk )κ2(1-τ)2E |x (t ∧σk -τ(t ∧σk ))|2Π2=V (x (0),0,r (0))㊃801㊃北京化工大学学报(自然科学版) 2023年Π3=ερJ 1(t ∧σk )(+λ24λ1-)ρJ 2(t ∧σk )J 2(t ∧σk )=E∫t ∧σke ε[s∫ss -δJ (v )d ]v d s易得J 1(t ∧σk )≤δJ 2(t ∧σk )㊂取ε1为ε1ρδ+λ24λ1-ρ=0的唯一解,则由ρ的定义知,对任意0<ε≤ε1,有Π3≤0㊂结合式(11),令k →∞,结合式(24),式(25)化为12h 1e εt E |x (t )|2≤Π1+Π2+Π4+Π5(26)其中,Π1=h 1e εt κ2(1-τ)2E |x (t -τ(t ))|2Π4=∫teεs{εh 3ρ-11[1+κ(1-τ)]p +q 1-2㊃[EH (x (s ))+κ(1-τ)EH (x (s -τ(s )))]-EH (x (s ))+(1-τ)αEH (x (s -τ(s )))}d sΠ5=∫te εs {ε(h 2+h 3)[1+κ(1-τ)]㊃[E |x (s )|2+κ(1-τ)E |x (s -τ(s ))|2]}d s +∫teε[s-λE |x (s )|2+(1-τ)βE |x (s -τ(s ))|2+2ρδ2λ24E |x (s -δ(s ))|2+λ4κ2(1-τ)22λ1E |x (s -τ(s ))-x (s -τ(s )-δ(s ))|]2d s对于Π2,由初值条件㊁假设2㊁假设8㊁引理2和式(12)得V (x (0),0,r (0))<∞,并且记为C 0,C 0为常数㊂对于Π4,根据假设3化简有Π4≤{[εh 3(1+κ(1-τ))p +q 1-2ρ-11](κe ετ+1)+e ετα-1}∫te εs E [H (x (s ))]d s +e ετ[εh 3(1+κ(1-τ))p +q 1-2ρ-11κ+α]∫-τe εs E [H (x (s ))]d s取ε2为[ε2h 3(1+κ(1-τ))p +q 1-2ρ-11](κe ε2τ+1)+e ε2τα-1=0的唯一解,则对任意0<ε≤ε2以及0<α<1即可满足Π4≤e ετ[εh 3(1+κ(1-τ))p +q 1-2ρ-11κ+α]㊃∫0-τe εs E [H (x (s ))]d s <∞(27)对于Π5,令ε3为ε3(h 2+h 3)(1+κ(1-τ))(1+e ε3τκ)+βe ε3τ+2ρδ2λ24eε3 δ1-δ+λ4κ2(1-τ)e ε3τ(1-τ-δ+e ε3δ(1-τ ))λ1(1-δ-τ)=λ的唯一解,对任意0<ε≤ε3,有Π5≤e [ετε(h 2+h 3)(1+κ(1-τ))κ+β+λ4κ2(1-τ)λ]1∫0-τe εs E |x (s )|2d s +2ρδ2λ24eεδ1-δ∫0-δe εs㊃E |x (s )|2d s +λ4κ2(1-τ)2e ε(τ+δ)λ1(1-δ-τ)∫-δ-τe εs E |x (s )|2d s [+ε(h 2+h 3)(1+κ-κτ)(1+e ετκ)+βe ετ+2ρδ2λ24eεδ1-δ+λ4κ2(1-τ)e ετ(1-τ-δ+e εδ(1-τ ))λ1(1-δ-τ)-]λ∫te εs E |x (s )|2d s ≤e [ετε(h 2+h 3)(1+κ(1-τ))κ+β+λ4κ2(1-τ)λ]1∫0-τe εs E |x (s )|2d s +2ρδ2λ24e εδ1-δ∫-δe εsE |x (s )|2d s +λ4κ2(1-τ)2e ε(τ+δ)λ1(1-δ-τ)㊃∫-δ-τe εs E |x (s )|2d s <∞(28)综上对任意0<ε≤ε1∧ε2∧ε3,可得12h 1e εt E |x (t )|2≤h 1e εt κ2(1-τ)2E |x (t -τ(t ))|2+C 1(29)其中C 1是一个常数㊂2)第二步式(29)经过整理可以得到e εt E |x (t )|2≤2e ετe ε(t -τ(t ))κ2(1-τ)2E |x (t -τ(t ))|2+2C 1h 1,故有sup 0≤s ≤t e εs E |x (s )|2≤2C 1h 1+2e ετκ2(1-τ)2sup 0≤s ≤t e εs ㊃E |x (s )|2+2κ2(1-τ)2e ετsup -τ≤s ≤0‖ϕ‖2由κ(1-τ)<12,令ε4为1-2e ε4τκ2(1-τ)2=0的唯一解,则对任意0<ε≤ε1∧ε2∧ε3∧ε4,有sup 0≤s ≤t e εs E |x (s )|2≤2C 1h 1+2κ2(1-τ)2e ετsup -τ≤s ≤0‖φ‖21-2κ2(1-τ)2e ετ:=C 2即当t ∈[0,∞)时,e εt E |x (t )|2≤C 2,即E |x (t )|2≤C 2e -εt ㊂对于任意的q ∈[2,w ),由Hölder 不等式得到㊃901㊃第6期刘　琪等:变时滞反馈控制的混合中立型随机延迟微分方程的指数稳定性E |x (t )|q≤(E |x (t )|2)w -　qw -2(E |x (t )|w)q -2w -2㊂由引理1知C 3:=E |x (t )|w <∞,故E |x (t )|q ≤C q -2w -23(C 2e -εt )w - qw -2≤C 4e -εt w - qw -2所以式(17)成立㊂特别地,当q =2时,有式(18)成立㊂3　例子考虑一维HNSDDEd[x (t )-N (x (t -τ(t )),t ,r (t ))]=f (x (t ),x (t -τ(t )),t ,r (t ))d t +g (x (t ),x (t -τ(t )),t ,r (t ))d B (t ),t ≥0(30)其中f (x ,y ,t ,1)=0.5x +y 3-6x 3f (x ,y ,t ,2)=x +y 3-4x3g (x ,y ,t ,1)=g (x ,y ,t ,2)=0.5y 2τ(t )=0.1(1-cos t ),N (y )=0.1y显然f ,g 不满足线性增长条件㊂令r (t )为一个连续的马氏链,状态空间S ={1,2},算子Γ=-22æèçöø÷1-1,B (t )为标准布朗运动且独立于r (t )㊂定义初值x (u )=0.2+cos u ,u ∈[-0.2,0],r (0)=2㊂由文献[10]可知系统(30)不稳定,以下将通过引入一个反馈控制函数使系统稳定㊂增加控制函数u (x ,t ,1)=-x ,u (x ,t ,2)=-2x ,增加控制函数后系统(3)的具体形式为 d[x (t )-0.1x (t -τ(t ))](=12x (t )+(x (t -τ(t )))3-6x (t )3-x (t - δ(t )))d t +12(x (t -τ(t )))2d B (t ),i (=1x (t )+(x (t -τ(t )))3-4x (t )3-2x (t - δ(t )))d t +12(x (t -τ(t )))2d B (t ),i ìîíïïïïïïïïïüþýïïïïïïïïï=2其中δ(t )=τ(t )㊂以下验证假设1~8㊂假设1显然成立㊂令m 1=3,m 2=2,可知假设2成立㊂令λ4=2,可知假设8成立㊂假设3对如下常数成立:δ=τ=0.2,δ=τ=0.1,且假设4对κ=19成立㊂取U 1(x ,t )=V (x ,i ,t )=|x |6,U 2(x ,t )=2.2x 6+x 8,由Young 不等式可得L V (x ,y ,t ,i )+V x (x -N (y ),t ,i )u (z ,t ,i )≤sup x ∈(43x 6-0.229x 8)-8×U 2(x ,t )+589×(1-τ)×U 2(y ,t -τ(t ))+109×(1-δ)×U 2(z ,t -δ(t ))故假设5对c 1=sup x ∈(43x 6-0.229x 8)<∞,c 2=8,c 3=589,c 4=109成立㊂取p =4,q 1=3,可知假设6成立㊂取U (x ,t ,i )=2x 2+x 4,i =1x 2+x 4,i ={2,再由Young 不等式,令λ1=0.05,λ2=0.1,λ3=4可得l U (x ,y ,t ,i )+λ1|U x (^x(t ),t ,i )|2+λ2㊃|f (x ,y ,t ,i )|2+λ3|g (x ,y ,t ,i )|2≤-1.845|x |2+0.369(1-τ)|y |2-6(x 4+x 6)+0.955×(1-τ)×6(y 4+y 6)若令H (x )=6(x 4+x 6),λ=1.845,β=0.369,α=0.955,则假设7成立㊂根据定理1条件发现κ,τ取值合理,进而可以得到δ≤0.0576时,定理1所有条件成立,故对∀w ≥6,∀q ∈[2,w ),存在ε>0使得lim t →∞sup1t ln (E |x (t )|q )≤-εw -qw -2特别地,q =2时有lim t →∞sup1tln (E |x (t )|2)≤-ε㊂4　结论本文采用函数方法,受文献[5]的启发在多项式增长的条件下讨论了变时滞反馈控制下的HNS⁃DDEs 的指数稳定性㊂最后,用一个例子证明了结论的有效性㊂参考文献:[1]　MAO X R,YUAN C G.Stochastic differential equations with Markovian switching[M].London:Imperial CollegePress,2006.[2]　FEI W Y,HU L J,MAO X R,et al.Delay dependentstability of highly nonlinear hybrid stochastic systems[J].Automatica,2017,82:165-170.[3]　FEI C,SHEN M X,FEI W Y,et al.Stability of highlynonlinear hybrid stochastic integro⁃differential delay equa⁃tions[J].Nonlinear Analysis:Hybrid Systems,2019,31:180-199.㊃011㊃北京化工大学学报(自然科学版) 2023年[4]　HU L J,MAO X R,SHEN Y.Stability and boundednessof nonlinear hybrid stochastic differential delay equations [J].Systems &Control Letters,2013,62:178-187.[5]　WU A Q,YOU S R,MAO W,et al.On exponential sta⁃bility of hybrid neutral stochastic differential delay equa⁃tions with different structures [J].Nonlinear Analysis:Hybrid Systems,2021,39:100971.[6]　SHEN M X,FEI W Y,MAO X R,et al.Stability ofhighly nonlinear neutral stochastic differential delay equa⁃tions[J].Systems &Control Letters,2018,115:1-8.[7]　SHEN M X,FEI C,FEI W Y,et al.Boundedness andstability of highly nonlinear hybrid neutral stochastic sys⁃tems with multiple delays[J].Science China Information Sciences,2019,62:202205.[8]　LI X Y,MAO X R.Stabilisation of highly nonlinear hy⁃brid stochastic differential delay equations by delay feed⁃back control[J].Automatica,2020,112:108657.[9]　周之薇,宋瑞丽.变时滞反馈控制的混合中立型随机延迟微分方程的稳定性[J].井冈山大学学报(自然科学版),2022,43(3):6-14.ZHOU Z W,SONG R L.Stabilization of the hybrid neu⁃tral stochastic differential equations controlled by thetime⁃varying delay feedback [J].Journal of Jinggangshan University (Natural Science),2022,43(3):6-14.(in Chinese)[10]SHEN M X,FEI C,FEI W Y,et al.Stabilisation by de⁃lay feedback control for highly nonlinear neutral stochasticdifferential equations [J ].Systems &Control Letters,2020,137:104645.[11]CHEN W M,XU S Y,ZOU Y.Stabilization of hybridneutral stochastic differential delay equations by delayfeedback control[J].Systems &Control Letters,2016,88:1-13.Exponential stability of hybrid neutral stochastic differential delay equations with time⁃dependent delay feedback controlLIU Qi　LAN GuangQiang *(College of Mathematics and Physics,Beijing University of Chemical Technology,Beijing 100029,China)Abstract :The exponential stability of hybrid neutral stochastic differential delay equations (HNSDDEs)with time⁃dependent delay feedback control has been ing the Lyapunov function method,the exponential sta⁃bility of the system can be obtained by setting an appropriate feedback control function with a variable ⁃pared with the existing research results,the results of this work increase our understanding of the exponential stabil⁃ity of HNSDDEs under the influence of variable delay feedback.Finally,an example is given to prove the validity of the conclusions.Key words :time⁃dependent delay;hybrid neutral stochastic differential delay equations (HNSDDEs);feedbackcontrol;exponential stability(责任编辑:吴万玲)㊃111㊃第6期刘　琪等:变时滞反馈控制的混合中立型随机延迟微分方程的指数稳定性。

METHOD OF ADAPTIVE INTERPOLATION FILTERING IN VIDE

专利名称：METHOD OF ADAPTIVE INTERPOLATION FILTERING IN VIDEO CODING发明人：CHEN, Ching-Yeh,HUANG, Yu-Wen申请号：EP15774443.4申请日：20150401公开号：EP3111643B1公开日：20190925专利内容由知识产权出版社提供摘要：A method and apparatus of adaptive interpolation filter for motion compensation with fractional-pixel accuracy are disclosed. Embodiments of the present invention generate interpolated reference samples at non-integer locations based on existing reference samples in a reference block by using an interpolation filter set adaptively according to pixel location and/or pixel characteristics. A current block is then encoded or decoded using a temporal predictor including the interpolated reference samples. The adaptive interpolation filter can be applied to the prediction unit (PU). In one embodiment, the interpolation filter set consists of interpolation filters having different filter lengths. An interpolation filter with a longer tap length is applied to generate interpolated reference samples farther from the block boundary and an interpolation filter with a shorter tap length is applied to generate interpolated reference samples closer to the block boundary.申请人：MediaTek Inc.代理机构：Habermann, Hruschka & Schnabel更多信息请下载全文后查看。

(武汉大学)分子生物学考研名词汇总

（武汉大学）分子生物学考研名词汇总●base flipping 碱基翻出●denaturation 变性DNA双链的氢键断裂，最后完全变成单链的过程●renaturation 复性热变性的DNA经缓慢冷却，从单链恢复成双链的过程●hybridization 杂交●hyperchromicity 增色效应●ribozyme 核酶一类具有催化活性的RNA分子，通过催化靶位点RNA链中磷酸二酯键的断裂，特异性地剪切底物RNA分子，从而阻断基因的表达●homolog 同源染色体●transposable element 转座因子●transposition 转座遗传信息从一个基因座转移至另一个基因座的现象成为基因转座，是由转座因子介导的遗传物质重排●kinetochore 动粒●telomerase 端粒酶●histone chaperone 组蛋白伴侣●proofreading 校正阅读●polymerase switching 聚合酶转换●replication folk 复制叉刚分开的模板链与双链DNA的连接区●leading strand 前导链在DNA复制过程中，与复制叉运动方向相同，以5’-3’方向连续合成的链被称为前导链●lagging strand 后随链在DNA复制过程中，与复制叉运动方向相反的，不连续延伸的DNA链被称为后随链●Okazaki fragment 冈崎片段●primase 引物酶依赖于DNA的RNA聚合酶，其功能是在DNA复制过程中合成RNA引物●primer 引物是指一段较短的单链RNA或DNA，它能与DNA的一条链配对提供游离的3’-OH末端以作为DNA聚合酶合成脱氧核苷酸链的起始点●DNA helicase DNA解旋酶●single-strand DNA binding protein, SSB 单链DNA结合蛋白●cooperative binding 协同结合●sliding DNA clamp DNA滑动夹●sliding clamp loader 滑动夹装载器●replisome 复制体●replicon 复制子单独复制的一个DNA单元称为一个复制子，一个复制子在一个细胞周期内仅复制一次●replicator 复制器●initiator protein 起始子蛋白●end replication problem 末端复制问题●homologous recombination 同源重组●strand invasion 链侵入●Holliday junction Holliday联结体●branch migration 分支移位●joint molecule 连接分子●synthesis-dependent strand annealing, SDSA 合成依赖性链退火●gene conversion 基因转变●conservative site-specific recombination, CSSR 保守性位点特异性重组●recombination site 重组位点●recombinase recognition sequence 重组酶识别序列●crossover region 交换区●serine recombinase 丝氨酸重组酶●tyrosine recombinase 酪氨酸重组酶●lysogenic state 溶原状态●lytic growth 裂解生长●transposon 转座子能够在没有序列相关性的情况下独立插入基因组新位点上的一段DNA序列，是存在与染色体DNA上可自主复制和位移的基本单位。

基于自适应遗传算法的多无人机协同任务分配

2021,36(1)电子信息对抗技术Electronic Information Warfare Technology㊀㊀中图分类号:V279;TN97㊀㊀㊀㊀㊀㊀文献标志码:A㊀㊀㊀㊀㊀㊀文章编号:1674-2230(2021)01-0059-06收稿日期:2020-02-28;修回日期:2020-03-30作者简介:王树朋(1990 ),男,博士,工程师㊂基于自适应遗传算法的多无人机协同任务分配王树朋,徐㊀旺,刘湘德,邓小龙(电子信息控制重点实验室,成都610036)摘要:提出一种自适应遗传算法,利用基于任务价值㊁飞行航程和任务分配均衡性的适应度函数评估任务分配方案的优劣,在算法运行过程中交叉率和变异率进行实时动态调整,以克服标准遗传算法易陷入局部最优的缺点㊂将提出的自适应遗传算法用于多无人机协同任务分配问题的求解,设置并进行了实验㊂实验结果表明:提出的自适应遗传算法可以较好地解决多无人机协同任务分配问题,得到较高的作战效能,证明了该方法的有效性㊂关键词:遗传算法;适应度函数;无人机;任务分配;作战效能DOI :10.3969/j.issn.1674-2230.2021.01.013Cooperative Task Assignment for Multi -UAVBased on Adaptive Genetic AlgorithmWANG Shupeng,XU Wang,LIU Xiangde,DENG Xiaolong(Science and Technology on Electronic Information Control Laboratory,Chengdu 610036,China)Abstract :An improved adaptive genetic algorithm is proposed,and a fitness function based ontask value,flying distance and the balance of task allocation scheme is used to evaluate the qualityof task allocation schemes.In the proposed algorithm,the crossover probability and mutation prob-ability can adjust automatically to avoid effectively the phenomenon of the standard genetic algo-rithm falling into the local optimum.The proposed improved genetic algorithm is used to solve the problem of cooperative task assignment for multiple Unmanned Aerial Vehicles (UAVs).The ex-periments are conducted and the experimental results show that the proposed adaptive genetic al-gorithm can significantly solve the problem and obtain an excellent combat effectiveness.The ef-fectiveness of the proposed method is demonstrated with the experimental results.Key words :genetic algorithm;fitness function;UAV;task assignment;combat effectiveness1㊀引言无人机是一种依靠程序自主操纵或受无线遥控的飞行器[1],在军事科技方面得到了极大重视,是新颖军事技术和新型武器平台的杰出代表㊂随着战场环境日益复杂,对于无人机的性能要求越来越高,单一无人机在复杂的战场环境中执行任务具有诸多不足,通常多个无人机进行协同作战或者执行任务㊂通常地,多无人机协同任务分配是:在无人机种类和数量已知的情况下,基于一定的环境信息和任务需求,为多个无人机分配一个或者一组有序的任务,要求在完成任务最大化的同时,多个无人机任务执行的整体效能最大,且所付出的代价最小㊂从理论上讲,多无人机协同任务分配属于NP -hard 的组合优化问题,通常需95王树朋,徐㊀旺,刘湘德,邓小龙基于自适应遗传算法的多无人机协同任务分配投稿邮箱:dzxxdkjs@要借助于算法进行求解㊂目前,国内外研究人员已经对于多无人机协同任务分配问题进行了大量的研究,并提出很多用于解决该问题的算法,主要有:群算法㊁自由市场机制算法和进化算法等㊂群算法是模拟自然界生物群体的行为的算法,其中蚁群算法[2-3]㊁粒子群算法[4]以及鱼群算法[5]是最为典型的群算法㊂研究人员发现群算法可以用于求解多无人机协同任务分配问题,但是该算法极易得到局部最优而非全局最优㊂自由市场机制算法[6]是利用明确的规则引导买卖双方进行公开竞价,在短时间内将资源合理化,得到问题的最优解和较优解㊂进化算法适合求解大规模问题,其中遗传算法[7-8]是最著名的进化算法㊂遗传算法在运行过程中会出现不容易收敛或陷入局部最优的问题,许多研究人员针对该问题对遗传算法进行了改进㊂本文提出一种改进的自适应遗传算法,在算法运行过程中适应度值㊁交叉率和变异率可以进行实时动态调整,以克服遗传算法易陷入局部最优的缺点,并利用该算法解决多无人机协同任务分配问题,以求在满足一定的约束条件下,无人机执行任务的整体收益最大,同时付出的代价最小,得到较大的效费比㊂2㊀问题描述㊀㊀多无人机协同任务分配模型是通过设置并满足一定约束条件的情况下,包括无人机的自身能力限制和环境以及任务的要求等,估算各个无人机执行任务获得的收益以及付出的代价,并利用评价指标进行评价,以求得到最大的收益损耗比和最优作战效能㊂通常情况下,多无人机协同任务分配需满足以下约束:1)每个任务只能被分配一次;2)无人机可以携带燃料限制造成的最大航程约束;3)无人机载荷限制,无人机要执行某项任务必须装载相应的载荷㊂另外,多无人机协同任务分配需要遵循以下原则:1)收益最高:每项任务都拥有它的价值,任务分配方案应该得到最大整体收益;2)航程最小:应该尽快完成任务,尽可能减小飞行航程,这样易满足无人机的航程限制,同时降低无人机面临的威胁;3)各个无人机的任务负载尽可能均衡,通常以任务个数或者飞行航程作为标准判定; 4)优先执行价值高的任务㊂根据以上原则,提出多无人机协同任务分配的评价指标,包括:1)任务价值指标:用于评估任务分配方案可以得到的整体收益;2)任务分配均衡性指标:用于评估无人机的任务负载是否均衡;3)飞行航程指标:用于评估无人机的飞行航程㊂3㊀遗传算法㊀㊀要将遗传算法用于多无人机协同任务分配问题的求解,可以将任务分配方案当作种群中的个体,确定合适的染色体编码方法,利用按照一定结构组成的染色体表示任务分配方案㊂然后,通过选择㊁交叉和变异等遗传操作进行不断进化,直到满足约束条件㊂通常来说,遗传算法可以表示为GA=(C,E, P0,M,F,G,Y,T),其中C㊁E㊁P0和M分别表示染色体编码方法㊁适应度函数㊁初始种群和种群大小,在本文的应用中,P0和M分别表示初始的任务分配方案集合以及任务分配方案的个数;F㊁G 和Y分别表示选择算子㊁交叉算子和变异算子;T 表示终止的条件和规则㊂因此,利用遗传算法解决多无人机协同任务分配问题的主要工作是确定以上8个参数㊂3.1㊀编码方法利用由一定结构组成的染色体表示任务分配方案,将一个任务分配方案转换为一条染色体的过程可以分为2个步骤:第一步是根据各个无人机需执行的任务确定各个无人机对应的染色体;第二步是将这些小的染色体结合,形成整个任务分配方案对应的完整染色体㊂假设无人机和任务的个数分别为N u和N t,其中第i个无人机U i的06电子信息对抗技术㊃第36卷2021年1月第1期王树朋,徐㊀旺,刘湘德,邓小龙基于自适应遗传算法的多无人机协同任务分配任务共有k个,分别是T i1㊁T i2㊁㊁T ik,则该无人机对应的任务染色体为[T i1T i2 T ik]㊂在任务分配时,可能出现N t个任务全部分配给一个无人机的情况,另外为增加随机性和扩展性,提高遗传算法的全局搜索能力,随机将N t-k个0插入到以上的任务染色体中,产生一条全新的长度为N t的染色体㊂最终,一个任务分配方案可以转换为一条长度为N u∗N t的染色体㊂3.2㊀适应度函数在本文的应用中,适应度函数E是用于判断任务分配方案的质量,根据上文提出的多无人机协同任务分配问题的原则和评价指标可知,主要利用任务价值指标㊁任务分配均衡性指标以及飞行航程指标等三个指标判定任务分配方案的质量㊂假设有N u个无人机,F i表示第i个无人机U i的飞行航程,整个任务的总飞行航程F t可以表示为:F t=ðN u i=1F i(1)无人机的平均航程为:F=F t Nu(2)无人机飞行航程的方差D可以表示为:D=ðN u i=1F i-F-()2N u(3)为充分考虑任务价值㊁飞行航程以及各个无人机任务的均衡性,将任务分配方案的适应度函数定义为:E=V ta∗F t+b∗D(4)其中:V t为任务的总价值,F t为总飞行航程,D为各个无人机飞行航程的方差,a和b分别表示飞行航程以及飞行航程均衡性的权重㊂另外,任务分配方案的收益损耗比GL可以表示为:GL=V tF t(5)另外,在遗传算法运行的不同阶段,需要对任务分配方案的适应度进行适当地扩大或者缩小,新的适应度函数E可以表示为:Eᶄ=1-e-αEα=m tE max-E avg+1,m=1+lg T()ìîíïïïï(6)其中:E为利用公式(4)计算得到的原适应度值, E avg为适应度值的平均值,E max为适应度最大值,t 为算法的运行次数,T为遗传算法的终止条件㊂在遗传算法运行初期,E max-E avg较大,而t较小,因此α较小,可以提高低质量任务分配方案的选择概率,同时降低高质量任务分配方案的选择概率;随着算法的运行,E max-E avg将逐渐减小,t 将逐渐增大,因此α会逐渐增大,可以避免算法陷入随机选择和局部最优㊂3.3㊀种群大小㊁初始种群和终止条件按照通常做法,将种群大小M的取值范围设定为20~100㊂首先,随机产生2∗M个符合要求的任务分配方案,利用公式(4)计算各个任务分配方案的适应度值㊂然后,从中选取出适应度值较高的M 个任务分配方案组成初始种群P0,即初始任务分配方案集合㊂终止条件T设定为:在规定的迭代次数内有一个任务分配方案的适应度值满足条件,则停止进化;否则,一直运行到规定的迭代次数㊂3.4㊀选择算子首先,采用精英保留策略将当前适应度值最大的一个任务分配方案直接保留到下一代,提高遗传算法的全局收敛能力㊂随后,利用最知名的轮盘赌选择法选择出剩余的任务分配方案㊂3.5㊀交叉算子和变异算子在算法运行过程中需随时动态调整p c和p m,动态调整的原则如下:1)适当降低适应度值比平均适应度值高的任务分配方案的p c和p m,以保护优秀的高质量任务分配方案,加快算法的收敛速度;2)适当增大适应度值比平均适应度值低的任务分配方案的p c和p m,以免算法陷入局部最优㊂另外,任务分配方案的集中度β也是决定p c 和p m的重要因素,β可以表示为:16王树朋,徐㊀旺,刘湘德,邓小龙基于自适应遗传算法的多无人机协同任务分配投稿邮箱:dzxxdkjs@β=E avgE max(7)其中:E avg 表示平均适应度值;E max 表示最大适应度值㊂显然,β越大,任务分配方案越集中,遗传算法越容易陷入局部最优㊂因此,随着β增大,p c 和p m 应该随之增大㊂基于以上原则,定义p c 和p m 如下:p c =0.8E avg -Eᵡ()+0.6Eᵡ-E min ()E avg -E min +0.2㊃βEᵡ<E avg 0.6E max -Eᵡ()+0.4Eᵡ-E avg ()E max -E avg +0.2㊃βEᵡȡE avgìîíïïïïïp m =0.08E avg -E‴()+0.05E‴-E min ()E avg -E min +0.02㊃βE‴<E avg and β<0.80.05E max -E‴()+0.0001E‴-E avg ()E max -E avg+0.02㊃βE‴ȡE avg and β<0.80.5βȡ0.8ìîíïïïïïï(8)其中:E max 为最大适应度值,E min 为最小适应度值,E avg 为平均适应度值,Eᵡ为进行交叉操作的两个任务分配方案中的较大适应度值,E‴为进行变异操作的任务分配方案的适应度值,β为任务分配方案的集中度,可利用公式(7)计算得到㊂4㊀实验结果4.1㊀实验设置4架无人机从指定的起飞机场起飞,飞至5个任务目标点执行10项任务,最终降落到指定的降落机场㊂其中,如表1所示,无人机的编号分别为UAV 1㊁UAV 2㊁UAV 3和UAV 4㊂另外,起飞机场㊁降落机场㊁目标如图6所示㊂任务的编号分别为任务1至任务10(简称为T 1㊁T 2㊁㊁T 10),每项任务均为到某一个目标点执行侦察㊁攻击㊁事后评估中的某一项,任务设置如表2所示㊂表1㊀无人机信息编号最大航程装载载荷UAV 120侦察㊁攻击UAV 120侦察UAV 125攻击㊁评估UAV 130侦察㊁评估图1㊀任务目标位置示意图表2㊀任务设置任务编号目标编号任务类型任务价值T 11侦察1T 21攻击2T 32攻击3T 42评估3T 53侦察4T 63评估6T 74侦察2T 84攻击3T 94评估5T 105评估14.2㊀第一组实验首先,随机地进行任务分配,得到一个满足多无人机协同任务分配的约束条件的任务分配方案如下:㊃UAV 1:T 2ңT 5㊃UAV 2:T 1ңT 7㊃UAV 3:T 3ңT 6ңT 8㊃UAV 4:T 4ңT 9ңT 10计算可知,4个无人机的飞行航程分别是14.0674㊁12.6023㊁20.1854和22.1873,飞行总航程为69.0423,执行任务的总价值为30,最终的收益损耗比约为0.43㊂另外,各个飞行器飞行航程的方差约为16.18,UAV 1和UAV 2的飞行航程相对较短,而UAV 3和UAV 4的飞行航程相对较长,各个无人机之间的均衡性存在明显不足㊂为提高收益损耗比,分别利用标准遗传算法和本文提出的自适应遗传算法进行优化,两个算法的参数设置如表3所示㊂26电子信息对抗技术·第36卷2021年1月第1期王树朋,徐㊀旺,刘湘德,邓小龙基于自适应遗传算法的多无人机协同任务分配表3㊀遗传算法参数设置参数名称标准遗传算法自适应遗传算法E 公式(4)公式(6)M 2020选择方法精英策略轮盘赌选择法精英策略轮盘赌选择法P c 0.8公式(8)交叉方法单点交叉单点交叉P m 0.2公式(8)T500500最终,利用标准遗传算法得到任务分配方案如下:㊃UAV 1:T 3ңT 8㊃UAV 2:T 1ңT 7㊃UAV 3:T 9㊃UAV 4:T 6ңT 5计算可得,4个无人机的飞行航程分别为12.78㊁12.6023㊁12.434和12.9443,总飞行航程为50.7605,总任务价值为24,计算可知收益损耗比约为0.47,相对于随机任务分配提高约9.3%㊂另外,各个飞行器飞行航程的方差约为0.04,无人机飞行航程比较均衡,未出现飞行航程过长或过短的情况㊂在算法运行过程中,最佳适应度曲线如图2所示,在遗传算法约迭代到第160次时陷入局部最优,全局搜索能力不足㊂图2㊀标准遗传算法的最佳适应度曲线图1为进一步提高算法的效率,利用本文提出的改进自适应遗传算法解决多无人机协同任务分配问题㊂最终,利用自适应遗传算法得到的任务分配方案如下:㊃UAV 1:T 2ңT 3ңT 8ңT 7㊃UAV 2:T 5㊃UAV 3:T 6㊃UAV 4:T 1ңT 4ңT 9计算可知,4个无人机的飞行航程分别为12.8191㊁12.9443㊁12.9443和12.8191,总飞行航程为51.5268,总任务价值为29,收益耗比约为0.56,相对于随机任务分配提高约30.2%,相对于基于标准遗传算法的任务分配方案提高约19.1%㊂另外,各个飞行器飞行航程的方差约为0.004,无人机飞行航程的均衡性相对于基于标准遗传算法的任务分配方案有了进一步的提高㊂在算法运行过程中,最佳适应度值曲线如图3所示,可以有效避免遗传算法陷入局部最优或者随机选择㊂图3㊀自适应遗传算法的最佳适应度曲线图14.3㊀第二组实验在第一组实验中,因任务10(简称为T 10)的价值较低,在最终的任务分配方案中极少被分配㊂在第二组实验中,将T 10的价值由1调整为6,其他设置项不变㊂首先,随机进行任务分配,最终的任务分配方案和第一组实验相同㊂随后,利用标准遗传算法进行多无人机协同任务分配,最终的任务分配方案如下:㊃UAV 1:T 2ңT 3ңT 7ңT 8㊃UAV 2:T 5㊃UAV 3:T 6ңT 10㊃UAV 4:T 9基于此任务分配方案,4个无人机的飞行航程分别为12.8191㊁12.9443㊁13.6883和12.434,总飞行航程为51.8857,总任务价值为31,因此计36王树朋,徐㊀旺,刘湘德,邓小龙基于自适应遗传算法的多无人机协同任务分配投稿邮箱:dzxxdkjs@算可得收益损耗比约为0.6,相对于随机任务分配提高约17.6%㊂另外,各个飞行器飞行航程的方差约为0.21,各个无人机的飞行航程的均衡性一般,相对于随机任务分配有一定的提高㊂在算法运行过程中,最佳适应度值曲线如图4所示,在算法迭代运行约90次时陷入较长时间的局部最优,直到迭代次数为340次时,然后再次陷入局部最优㊂图4㊀标准遗传算法的最佳适应度曲线图2最后,将本文提出的自适应遗传算法用于多无人机协同任务分配问题的求解,得到最终的任务分配方案如下:㊃UAV 1:T 2ңT 3ңT 8ңT 7㊃UAV 2:T 5㊃UAV 3:T 6ңT 10㊃UAV 4:T 1ңT 4ңT 9基于此任务分配方案可得,4个无人机的航程分别是12.8191㊁12.9443㊁13.6883以及12.8191,总飞行航程为52.2708,总任务价值为35,计算可得效益损耗比约为0.67,相对于利用标准遗传算法得到的任务分配方案有了进一步提高㊂另外,各个无人机飞行航程的方差约为0.13,飞行航程的均衡性较好㊂在算法运行过程中,最佳适应度值曲线如图5所示,适应度值一直在实时动态变化,可以有效避免遗传算法陷入局部最优或者随机选择㊂由实验结果可得,当任务10的任务价值从1调整为6以后,不再出现该任务没有无人机执行的情况,这说明利用遗传算法进行多无人机协同任务分配可以根据任务的价值以及代价进行实时动态调整,符合优先执行价值高的任务的原则㊂图5㊀自适应遗传算法的最佳适应度曲线图25　结束语㊀㊀本文提出了一种基于自适应遗传算法的多无人机协同任务分配方法,整个遗传过程利用自适应的适应度函数评估任务分配结果的优劣,交叉率和变异率在算法运行过程中可以实时动态调整㊂实验结果表明,和随机进行任务分配相比,本文提出的方法在满足一定的原则和约束条件下,可以得到更高的收益损耗比,并且无人机飞行航程的均衡性更好㊂另外,和标准遗传算法相比,本文提出的改进遗传算法可以有效地扩展搜索空间,具有较高的全局搜索能力,不易陷入局部最优㊂参考文献:[1]㊀江更祥.浅谈无人机[J].制造业自动化,2011,33(8):110-112.[2]㊀楚瑞.基于蚁群算法的无人机航路规划[D].西安:西北工业大学,2006.[3]㊀杨剑峰.蚁群算法及其应用研究[D].杭州:浙江大学,2007.[4]㊀刘建华.粒子群算法的基本理论及其改进研究[D].长沙:中南大学,2009.[5]㊀李晓磊.一种新型的智能优化方法-人工鱼群算法[D].杭州:浙江大学,2003.[6]㊀AUSUBEL L M,MILGROM P R.Ascending AuctionsWith Package Bidding[J].Frontiers of Theoretical E-conomics,2002,1(1):1-42.[7]㊀刘昊旸.遗传算法研究及遗传算法工具箱开发[D].天津:天津大学,2005.[8]㊀牟健慧.基于混合遗传算法的车间逆调度方法研究[D].武汉:华中科技大学,2015.46。

杨阳整理-植物生理学英语

植物生理学词汇植物生理学 plant physiology message transportation 信息传递signal transduction 信号转导water potential 水势solute potential 溶质势osmotic potential 渗透势matric potential 衬质势diffusion 扩散osmosis 渗透plasmolysis 质壁分离deplasmolysis 质壁分离复原pressure potential 压力势turgor pressure 膨压bulk flow 集流aquaporin 水孔蛋白active absorption of water 主动吸水root pressure 根压blooding 伤流blooding sap 伤流液guttation 吐水apoplast 质外体symplast 共质体passive absorption of water 被动吸水transpiration pull 蒸腾拉力bound water 束缚水gravitational water 重力水cappilary water 毛细管水permanent wilting coefficient 永久萎蔫系数accumulation 积累性lenticular transpiration 皮孔蒸腾cuticular transpiration 角质层蒸腾stomatal transpiration 气孔蒸腾transpiration rate 蒸腾速率transpiration ratio 蒸腾效率transpiration coefficient 蒸腾系数small pore diffusion law 小孔扩散律feed back manner 反馈调节feed forward manner 前馈调节vapor pressure difficiency 叶片-大气水气压亏缺cohesion theory 内聚力学说mineral nutrition 矿质营养ash 灰分ash element 灰分元素mineral element 矿质元素essential element 必需元素solution culture method 溶液培养法water culture method 水培法sand culture method 沙基培养法balance solution 平衡溶液major element 大量元素minor element 微量元素nutrient deficiency symptom 营养缺乏症calcium binding proteins 钙结合蛋白calmodulin 钙调素beneficial elements 有益元素rare earth element 稀土元素selective absorption 选择吸收physiologically acid salt 生理酸性盐physiologically alkaline salt 生理碱性盐physiologically neutral salt 生理中性盐toxicity of single salt 单盐毒害ino antagonism 离子拮抗ion transporter 离子运载体ion channel 离子通道ion carrier 离子载体ion pump 离子泵voltage sensor 电压感受器permease 透过酶transport enzyme 运输酶ATPase ATP酶electrogenic pump 致电离子泵electroneutral pump 中性离子泵masterenzyme 主宰酶pinocytosh 胞饮作用simple diffusion 单纯扩散facilitated diffusion 协助扩散primary active transport 初始主动运输secondary active transport 次级主动运输co-transport 协同转运，共转运secondary co-transport 次级共转运proton mative force 跨膜质子电动势symport 同向转运antiport 反向转运ATP-binding complex ATP结合复合体contact exchange 接触交换foliar nutrition 叶片营养ectodesmata 外连丝nitrate reductase ，NR 硝酸还原酶induced enzyme 诱导酶adaptive enzyme 适应酶nitrite reductase 亚硝酸还原酶glutamine synthetase 谷氨酰胺合成酶glutamate synthase 谷氨酸合成酶carbon assimilation 碳素同化作用photosynthesis 光合作用chlorophyll 叶绿素phytol 植醇carotenoid 类胡萝卜素carotene 胡萝卜素lutein 叶黄素pigment protein complex 色素蛋白复合体phycobillin 藻胆素photon 光子quantum 光量子ground state 基态excited state 激发态light reaction 光反应dark reaction 暗反应reaction centre pigments 反应中心色素light-harvesting pigments 聚光色素antenna pigments 天线色素reaction center 反应中心photosynthetic unit 光合单位exciton transfer 激子传递resonance transfer 共振传递primary electron donor 原初电子供体primary electron acceptor 原初电子受体secondary electron donor 次级电子供体trap 陷阱red drop 红降现象Emerson effect 爱默生效应PSII light harvesting complex，LHC II : PSII 的捕光色素复合体pheo 去镁叶绿素plastoquinone 质体醌reductive pentose phosphate pathway，RPPP 还原戊糖磷酸途径GAP 甘油醛-3-磷酸z scheme z方案cytochrome，Cyt 细胞色素ferrdoxin,Fd 铁氧还蛋白plastocyanin,PC 质蓝素water photolysis 水的光解Hill reaction 希尔反应oxygen-evolving complex,OEC 放氧复合体manganese stablizing protein 锰稳定蛋白water oxidizing clock 水氧化钟noncyclic electron transport 非环式电子传递cyclic electron transport 环式电子传递pseudocyclic electron transport 假环式电子传递water-water cycle 水-水循环photosynthetic phosphorylation 光合磷酸化DNP 二硝基苯酚（解偶联剂）crassulacean acid metabolism,CAM 景天酸代谢the Calvin cycle 卡尔文循环oxaloacetic acid 草酰乙酸malic acid,Mal 苹果酸aspartic acid ,Asp天冬氨酸bundle sheath cell 维管束鞘细胞pyruvic acid 丙酮酸photo respiration 光呼吸light compensation point 光补偿点light saturation 光饱和现象photoinhibition of photosynthesis 光抑制midday depression 午睡现象aerobic respiration 有氧呼吸anaerobic respiration 无氧呼吸respiratory substrate 呼吸底物fermentation 发酵respiratory rate 呼吸速率respiratory quotient 呼吸商glycolysis 糖酵解tricarboxylic acid cycle 三羧酸循环elicitor 激发子biological oxidation 生物氧化barbital acid 巴比妥酸rotenone 鱼藤酮positive effector 正效应物negative effector 负效应物Pasteur effect 巴斯德效应maintenance respiration 维持呼吸growth respiration 生长呼吸confocal laser canning microscope 共聚集激光扫描显微镜empty seed coat technique 空种皮杯技术symplastic phloem loading 共质体装载apoplasmic phloem loading 质外体装载first messenger 第一信使chemical signal 化学信号positive chemical signal 正化学信号negative chemical signal 负化学信号physiocal signal 物理信号action potentials 动作电位variation potentials 变异电位receptor 受体blue light recepter 隐花色素，蓝光受体protein kinase 蛋白激酶phosphorlation 磷酸化作用transcription factor 转录因子plant growth substance 植物生长物质phytohormones 植物激素plant growth regulators 植物生长调节剂auxin 生长素IAA 吲哚乙酸hormone receptor 激素受体acid-growth theory 酸生长学说Gibberellins 赤霉素Gibberellic acid,GA 赤霉酸zeatin 玉米素cytokinin，CTK 细胞分裂素cytokinin oxidase,CKO 细胞分裂素氧化酶abscisin II 脱落素IIdormin 休眠素abscisic acid,ABA 脱落酸terpenoid pathway 类萜途径carotenoid pathway 类胡萝卜素途径xanthoxin 黄质醛lutein 叶黄素neoxanthix 新黄质brassinolide 油菜素内酯brassinosteroide 油菜素甾体类化合物bean bioassay 生物鉴定法jasmonates 茉莉酸Jasmonic acid methyl ester 茉莉酸甲酯linolenic acid α-亚麻酸cyclic fatty acid 环脂肪酸aspirin 阿司匹林salicylic acid ,SA 水杨酸polyamines,PA 多胺putrescine，Put 腐胺cadaverine,Cad 尸胺spermidine,Spd 亚精胺spermine,Spm 精胺CEPA 乙烯利NAA 萘乙酸NAD 萘乙酰胺6-BA 6-苄基腺嘌呤CCC 矮壮素PP333 多效唑growth 生长differentiation 分化development 发育chemical creep 化学滑行totipotency 细胞全能性polarity 极性explant 外植体tissue culture 组织培养primary culture 初代培养subculture 继代培养redifferentiation 再分化embryoid 胚状体somatic embryo 体细胞胚adventitious embryo 不定胚virus-free plants 无病毒植株light seed 需光种子dark seed 需暗种子seed longevity 种子寿命seed vigor 种子活力seed viability 种子生活力seed aging 种子老化determinate 有限性meristem 分生组织initial cell 原细胞seed deterioration 种子劣变indeterminate 无限性self-perpetuating 自我留存stem cell 干细胞quiescent center 静止中心tunica 原套corpus 原体central zone 中央区peripheral zone 周缘区vegetative meristem 营养分生组织floral meristem 成花分生组织growth periodicity 生长的周期性grand period of growth 生长大周期lagphase 停滞期logarithmic growth phase 指数期linear growth phase 线性期senescence phase 衰减期daily periodicity 昼夜周期性correlation 相关性apical dominance 顶端优势primigenic dominance 原发优势autoinhibition 自动抑制allelopathy 它感作用autotoxicity 自毒photomorphogenesis 光形态建成photoreceptor 光敏受体photosensor 光敏受体phytochrome 光敏色素thermoperiodicity of growth 生长的温周期现象tropic movement 向性运动nastic movement 感性运动phototropism 向光性geotropism 向地性gravitropism 向重力性positive/negative gravitropism 正/负向重力性diagravitropism 横向重力性statolith 平衡石amyloplast 淀粉体chemotropism 向化性hydrotropism 向水性turgor movement 紧张性运动nyctinasty 感夜性thermonasty 感温性seismonasty 感震性action potential 动作电位circadian rhythm 近似昼夜节律ripeness to flower state 花熟状态floral induction 成花诱导floral evocation 成花启动initiation of flower 花的发端floral development 花发育vernalization 春化作用devernalization 去春化作用revernalization 再春化作用vernalin 春化素bolting 抽薹photoperiod 光周期photoperiodism 光周期现象photoperiodic induction 光周期诱导critical dark period 临界暗期critical night 临界夜长florigen 成花素floral determinated state 成花决定态flower bud differentiation 花芽分化hermaphroditic plants 雌雄同株同花植物dioecious plants 雌雄异株植物androecious line 雄性系gynoecious line 雌性系fertility change 育性转化pollenin 花粉素recognition 识别group effect 集体效应parthenocarpy 单性结实phyrin 非丁respiratory climacteric 呼吸跃变dormancy 休眠epistotic dormancy 强迫休眠physiological dormancy 生理休眠after-ripening 后熟stratification 层积处理copigmentation 协同关系作用free radical 生物自由基programmed cell death 程序性细胞死亡apoptosis 细胞凋亡abscission 脱落stress 逆境，胁迫stress physiology 逆境生理strain 胁变escape 避性avoidance 御性tolerance 耐性hydraulic signal 水信号water mass flow 水流hydraustatic pressure 水压chemical signal 化学信号aquaporin 水孔蛋白proteinase inhibitor 蛋白酶抑制剂systemin 系统素electrical signal 电信号osmotin 渗调蛋白chaperone 分子伴侣water stress protein 水分胁迫蛋白heat shock protein 热激蛋白late embryogenesis abundant protein 胚胎发生晚期丰富蛋白lipid transfer protein 类脂转移蛋白kinase-regulated protein 激酶调节蛋白biotic stress 生物逆境pathogenesis-related protein 病程相关蛋白heavy metal binding protein 重金属结合蛋白phytochelatin 植物螯合肽cold-acclimation-induced protein 冷驯化诱导蛋白anaerobic stress protein 厌氧蛋白cross adaptation 交叉适应。

基于核酸适配体和阳离子聚合物PAH高效聚集纳米金比色法检测牛奶中四环素

基于核酸适配体和阳离子聚合物PAH高效聚集纳米金比色法检测牛奶中四环素罗艳芳;贺兰;詹深山;刘乐;支月娥;周培【摘要】为满足乳制品中四环素快速检测要求,开发了基于核酸适配体(aptamer)和阳离子聚合物PAH高效聚集纳米金比色检测牛奶中四环素(TET)的新方法.本文优化了PAH和适配体的浓度.最优实验条件下,四环素浓度在一定范围内与A520/A650呈现良好的线性关系,最低检测限(LOD)为95 nmol/L,对四环素具有良好的选择性.该方法已成功用于牛奶中四环素的检测,回收率为108％～117％,相对标准偏差为2.9％～3.6％.【期刊名称】《上海交通大学学报（农业科学版）》【年(卷),期】2014(032)006【总页数】6页(P66-70,91)【关键词】四环素;核酸适配体;PAH;纳米金;比色【作者】罗艳芳;贺兰;詹深山;刘乐;支月娥;周培【作者单位】上海交通大学农业与生物学院,上海200240;上海交通大学农业与生物学院,上海200240;上海交通大学农业与生物学院,上海200240;上海交通大学农业与生物学院,上海200240;上海交通大学农业与生物学院,上海200240;上海交通大学农业与生物学院,上海200240【正文语种】中文【中图分类】X83四环素是一种常见的广谱抗生素类药物,被广泛运用于人类细菌感染治疗及添加于畜禽饲料中[1]。

据报道,每年有5 000 t四环素被人类和动物消耗[2]。

随着四环素使用量的增加,其在食品和环境中的残留带来了一系列的问题,如:微生物抗药性增强、超级细菌的产生,食用具有抗生素残留肉制品后导致的过敏现象及某些器官的病变等等[3-4]。

为了保障消费者食品安全,欧盟规定牛奶中四环素最大残留为225 nmol/L[5],美国食品药品监督管理局规定牛奶中四环素最大残留为900 nmol/L[6]。

2002年,我国农业部修订的《动物性食品中兽药最高残留限量》中规定,牛羊奶以及所有动物性食品中四环素类药物残留的最高残留量为225 nmol/L。

高精度定位系统的摩擦力自适应前馈补偿

电气传动2021年第51卷第4期ELECTRIC DRIVE 2021Vol.51No.4摘要：为了有效抑制机电系统摩擦力等外部扰动对系统动态性能的影响，针对直驱伺服系统中往复定位存在的摩擦力，提出了一种基于自适应前馈控制器的摩擦力补偿策略，此方法能够有效利用参考模型与被控对象的位置跟踪误差等信息，在线实时确定自适应控制率，在保证系统稳定的条件下，能够有效克服系统摩擦力及模型慢时变等引起的系统动态性能异常。

针对直驱伺服系统建立其数学模型，根据数学模型确定自适应补偿环节的数学形式，并利用Lyapunov 函数证明了自适应控制率的稳定性。

最后通过试验表明，在跟踪正弦位置指令时，基于自适应前馈补偿的方法动态跟踪误差的均方根值为4.8μm ，与PID 无摩擦补偿控制方法相比，提高了47.3%，与传统模型参考自适应控制方法相比，提高了17.9%。

综上所述，所提方法可以有效抑制系统摩擦力干扰，提高系统动态跟踪精度。

关键词：自适应；前馈补偿；定位系统；摩擦力中图分类号：TP273+.5文献标识码：ADOI ：10.19457/j.1001-2095.dqcd20741Friction Adaptive Feedforward Compensation for High Precision Positioning SystemYANG Hong ，LI Shengming（College of Electromechanic and Automotive Engineering ，Qingyuan Polytechnic ，Qingyuan 511510，Guangdong ，China ）Abstract:In order to suppress the influence of external disturbances such as friction on the dynamic performance of electromechanical systems ，considering friction force for reciprocating positioning in direct drive servo system ，a friction compensation strategy based on adaptive feedforward controller was proposed.The method can effectively utilize the information of reference model and position tracking error of controlled object and determine the control rate on line.Under the condition of guaranteeing the stability of the system ，it can effectively overcome the abnormal dynamic performance of the system caused by system friction and slow time-varying model.The mathematical model of direct drive servo system and adaptive compensation component were established.Lyapunov function was adopted to guarantee the stability of the adaptive control rate.Finally ，experiments show that the root mean square value of dynamic tracking error based on adaptive feedforward compensation is 4.8μm when tracking sinusoidal position commands ，which is 47.3%higher than that of PID friction-free compensation control method and 17.9%higher than that of traditional model reference adaptive control method.In conclusion ，the proposed method can effectively suppress the friction interference and improve the dynamic tracking accuracy of the system.Key words:adaptive ；feedforward compensation ；positioning system ；friction高精度定位系统的摩擦力自适应前馈补偿杨红，李生明（清远职业技术学院机电与汽车工程学院，广东清远511510）基金项目：广东省高等职业教育教学改革研究与实践项目（GDJG2019380）作者简介：杨红（1969—），女，硕士，副教授，Email ：高精度定位系统广泛应用于航空航天、军工打印机、医疗器械及IC 装备等领域，定位系统的精度和响应速度等指标直接影响军用设备的加工精度及医疗器械的治疗效果等，因此研究有效提高定位系统的精度对国防军工、医疗卫生和生产生活的各领域有着重要意义。

磁共振成像技术中英文名词对照

驰豫增强快速采集
Reｓpirａｔorｙcompeｎsatiｏn , RC
呼吸补偿
Ｒectanｇleｆｉｅldｏｆview, RFOV
矩形视野
Ｒegiｏｎof inteｒesｔ,ＲＯI
感兴趣区
Sｐｉnecｈo,SＥ
自旋回波
Ｓｐｉｎｅcｈo-eｃhｏpｌanar imaging, SＥ-EPI
自旋-平面回波成像
肝脏容积加速采集
Lineｓcan , LS
线扫描
Mａｇnetizatｉｏｎｐrepaｒed fａsｔgｒaｄieｎt reｃａｌledechｏ,MP-ＦGRE
磁化准备快速梯度回波
Mａgｎetization pｒｅｐａredrapidｇraｄienｔechｏimaginｇ，MＰ－RAGE
磁化准备快速梯度回波成像
Ｎ-乙酰天门冬氨酸
Paｌseｄaｒterｉal spｉｎlaｂeling, PＡSL
脉冲式动脉自旋标记
Ｐaｒalｌelacquｉｓitioｎtｅｃhｎique,ＰＡT
并行采集技术
Phasｅｃontrast,PC
相位对比
Protｏn densｉtyweigｈtｅdimaging ,PDＷI
质子密度加权成像
化学位移成像
Ｄiffusioｎｔensor imaging ,ＤTI
扩散张量成像
Diffuｓｉｏn weiｇhted imaging，DWI
扩散加权成像
Echｏplaｎar iｍａging ,ＥPI
平面回波成像
Ｅchｏspaｃe ,ES
回波间隙
Ecｈo trａinlｅngth，ETL
回波链长度
Frａｃｔionａl anisotｒopy，ＦＡ

伊士达高Tg、低CTE、多功能填充环氧树脂和酚醛固化层压板和预浸料IT-180ABS IT-180A

IT-180ABS/IT-180ATCHigh Tg, Low CTE, Multifunctional Filled Epoxy Resin and Phenolic-Cured Laminate & PrepregIT-180A is an advanced high Tg (175℃ by DSC) multifunctional filled epoxy with low CTE, high thermal reliability and CAF resistance. It’s design for high layer PCB and can pass 260℃ Lead free assembly and sequential lamination process.Key Features =============================== Advanced High Tg Resin TechnologyIndustrial standard material with high Tg (175℃ by DSC) multifunctional filled epoxy resin and excellent thermal reliability.Lead-Free Assembly CompatibleRoHS compliant and suitable for high thermal reliability needs, and Lead free assemblies with a maximum reflow temperature of 260℃. Friendly Processing and CAF ResistanceFriendly PCB process like high Tg FR4. Users can short the learning curve when using this material.CAF ResistanceLow thermal expansion coefficient (CTE) helps to excellent thermal reliability and CAF resistance providing long-term reliability for industrial boards and automobile application.Available in Variety of ConstructionsAvailable in a various of constructions, copper weights and glass styles, including standard(HTE), RTF and VLP copper foil. ApplicationsMultilayer and High Layer PCB AutomobileBackplanesServers and Networking TelecommunicationsData StorageHeavy Copper ApplicationIndustrial ApprovalUL 94 V-0IPC-4101C Spec / 99/ 101/ 126 RoHS CompliantGlobal AvailabilityArea Address Contact e-mail TELTaiwan 22,Kung Yen 1st Rd. Ping Chen Industry Zone. Ping Chen,Taoyuan, Taiwan, R.O.C.Sales: *************.twTechnician: *****************.tw886-3-4152345 #3168886-3-4152345 #5300East China Chun Hui Rd., Xishan Economic Development Zone,Wuxi City, Jiangsu Province, ChinaSales : ****************Technician: *********************86-510-8223-5888 #516886-510-8223-5888 #3000South China168, Dongfang Road, Nanfang Industrial Park, BeiceVillage, Humen Town, Dongguan City, Guangdong Province, China Sales: ***********.cnTechnician : ***************.cn86-769-88623268 #32086-769-88623268 #550Japan No.2, Huafang Rd, Yonghe Economic Zone, Economic andTechnological Development Zone, Guangzhou,Guangdong Province, ChinaSales: ****************.cnTechnician : *****************.tw86-20-6286-8088 #8027886-3-4152345 #5388USA Tapco Circuit Supply1225 Greenbriar Drive, Suite AAddison, IL 60101, USASales: *******************************Technician : ********************************1-614-937-52051-310-699-8028Europe ITEQ Europe,Via L. Pergher, 16 38121 Trento, Italy Sales: ********************Technician : *********************39-0461-82052639-0461-820526REV 06-12ITEQ Laminate/ Prepreg : IT-180ATC / IT-180ABS IPC-4101C Spec / 99 / 101 / 126LAMINATE( IT-180ATC)Thickness<0.50 mm[0.0197 in] Thickness≧0.50 mm[0.0197 in] Units T est MethodPropertyTypical Value Spec Typical Value SpecMetric(English)IPC-TM-650(or as noted)Peel Strength, minimumA. Low profile copper foil and very low profile copperfoil - all copper weights > 17µm [0.669 mil]B. Standard profile copper foil1.After Thermal Stress2.At 125°C [257 F]3.After Process Solutions 0.88 (5.0)1.23 (7.0)1.05 (6.0)1.05 (6.0)0.70 (4.00)0.80 (4.57)0.70 (4.00)0.55 (3.14)0.88 (5.0)1.40 (8.0)1.23 (7.0)1.23 (7.0)0.70 (4.00)1.05 (6.00)0.70 (4.00)0.80 (4.57)N/mm(lb/inch)2.4.82.4.8.22.4.8.3Volume Resistivity, minimumA. C-96/35/90B. After moisture resistanceC. At elevated temperature E-24/125 3.0x1010--5.0x1010106--103--3.0x10101.0x1010--104103MΩ-cm 2.5.17.1Surface Resistivity, minimumA. C-96/35/90B. After moisture resistanceC. At elevated temperature E-24/125 3.0x1010--4.0x1010104--103--3.0x10104.0x1010--104103MΩ 2.5.17.1Moisture Absorption, maximum -- -- 0.12 0.8 % 2.6.2.1 Dielectric Breakdown, minimum -- -- 60 40 kV 2.5.6 Permittivity (Dk, 50% resin content)(Laminate & Laminated Prepreg)A. 1MHzB. 1GHzC. 2GHzD. 5GHzE. 10GHz 4.44.44.24.14.05.44.44.44.34.14.15.4 --2.5.5.92.5.5.13Loss Tangent (Df, 50% resin content) (Laminate & Laminated Prepreg)A. 1MHzB. 1GHzC. 2GHzD. 5GHzE. 10GHz 0.0150.0150.0150.0160.0170.0350.0140.0150.0150.0160.0160.035 --2.5.5.92.5.5.13Flexural Strength, minimumA. Length directionB. Cross direction ----------------500-530(72,500-76,850)410-440(59,450-63,800)415(60,190)345(50,140)N/mm2(lb/in2)2.4.4Arc Resistance, minimum 125 60 125 60 s 2.5.1 Thermal Stress 10 s at 288°C [550.4F],minimumA. UnetchedB. Etched PassPassPass VisualPass VisualPassPassPass VisualPass VisualRating 2.4.13.1Electric Strength, minimum(Laminate & Laminated Prepreg)45 30 -- -- kV/mm 2.5.6.2 Flammability,(Laminate & Laminated Prepreg)V-0 V-0 V-0 V-0 Rating UL94 Glass Transition Temperature(DSC) 175 170 minimum 175 170 minimum ˚C 2.4.25Decomposition Temperature-- -- 345 340 minimum ˚C2.4.24.6 (5% wt loss)X/Y Axis CTE (40℃ to 125℃) -- -- 10-13 -- PPM/˚C 2.4.24 Z-Axis CTEA. Alpha 1B. Alpha 2C. 50 to 260 Degrees C ------------452102.760 maximum300 maximum3.0 maximumPPM/˚CPPM/˚C%2.4.24Thermal ResistanceA. T260B. T288 -------->60>3030 minimum15 minimumMinutesMinutes2.4.24.1CAF Resistance -- -- Pass AABUS Pass/Fail 2.6.25The above data and fabrication guide provide designers and PCB shop for their reference. We believe that these information are accurate, however, the data may vary depend on the test methods and specification used. The actual sales of the product should be according to specification in the agreement between ITEQ and its customer. ITEQ reserves the right to revise its data at any time without notice and maintain the best information available to users.REV 06-12。

OPTICS EXPRESS

Long lifetime plasma channel in air generated by multiple femtosecond laser pulses and anexternal electrical fieldJiabin Zhu, Zhonggang Ji, Yunpei Deng, Jiansheng Liu, Ruxin Li, and Zhizhan Xu State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics (SIOM), ChineseAcademy of Sciences, Shanghai 201800, Chinajiabinzhu@Abstract: The lifetime of a plasma channel produced by self-guidingintense femtosecond laser pulses in air is largely prolonged by adding a highvoltage electrical field in the plasma and by introducing a series offemtosecond laser pulses. An optimal lifetime value is realized throughadjusting the delay among these laser pulses. The lifetime of a plasmachannel is greatly enhanced to 350 ns by using four sequential intense100fs(FWHM) laser pulses with an external electrical field of about350kV/m, which proves the feasibility of prolonging the lifetime of plasmaby adding an external electrical field and employing multiple laser pulses.© 2006 Optical Society of AmericaOCIS codes: (320.7120) ultrafast phenomena; (350.5400) plasmasReferences and links1. A. Braun, G. Korn, X. Liu, D. Du, J. Squier, and G. Mourou, “Self-channeling of high-peak-powerfemtosecond laser pulses in air,” Opt. Lett. 20, 73-75 (1995).2. E. T. J. Nibbering, P. F. Curley, G. Grillon, B. S. Prade, M. A. Franco, F. Salin, and A. Mysyrowicz,“Conical emission from self-guided femtosecond pulses in air,” Opt. Lett. 21, 62-64 (1996).3.Miguel Rodriguez, Riad Bourayou, Guillaume Méjean, Jérôme Kasparian, Jin Yu, Estelle Salmon,Alexander Scholz, Bringfried Stecklum, Jochen Eislöffel, Uwe Laux, Artie P. Hatzes, RolandSauerbrey, Ludger Wöste, and Jean-Pierre Wolf.“Kilometer-range nonlinear propagation offemtosecond laser pulses,” Phy. Rev. E 69, 036607 (2004).4.S. A. Hosseini, Q. Luo, B. Ferland, W. Liu, N. Akozbek, G. Roy, S.L. Chin, “Effective length of filamentsmeasurement using backscattered fluorescence from nitrogen molecules,” Appl. Phys. B 77, 697-702(2003).5.R. Ackermann, K. Stelmaszcyk, P. Rohwetter, G. Mejean, E. Salmon, J. Yu, J. Kasparian, G. Mechain,V.Bergmann, S. Schaper, B. Weise, T. Kumm, K.Rethmeier, W. Kalkner, L. Wöste, and J. P. Wolf,“Triggering and guiding of megavolt discharges by laser-induced filaments under rain conditions,”Appl.Phys. Lett. 85, 5781-5783 (2004).6. F. Vidal, D. Comtois, C.-Y. Chien, A. Desparois, B. La Fontaine, T. W. Johnston, J.-C. Kieffer, H. P.Mercure, and F. A. Rizk, “Modeling the triggering of streamers in air by ultrashort laser pulses,” IEEETrans. Plasma Sci. 28, 418–433 (2000).7.J. Kasparian, M. Rodriguez, G. Méjean, J. Yu, E. Salmon, H. Wille, R. Bourayou, S. Frey, Y.-B. André,A. Mysyrowicz, R. Sauerbrey, J.-P. Wolf, and L. Wöste, “White-Light Filaments for AtmosphericAnalysis,” Science 301, 61-64 (2003).8.H. Yang, J. Zhang, W. Yu, Y. J. Li, and Z. Y. Wei,“Long plasma channels generated by femtosecondlaser pulses,” Phys. Rev. E 65, 016406(2001).9.X. Lu, Xi Ting Ting, Li Ying-Jun, and Zhang Jie, “Lifetime of the plasma channel produced by ultra-shortand ultra-high power laser pulse in the air,” Acta Physica Sinica 53, 3404-3408 (2004).10.Hui Yang, Jie Zhang, Yingjun Li, Jun Zhang, Yutong Li, Zhenglin Chen, Hao Teng, Zhiyi Wei, andZhengming Sheng, “Characteristics of self-guided laser plasma channels generated by femtosecond laserpulses in air,” Phys. Rev. E 66, 016406(2002).11.X .M .Zhao, Jean-Claude Diels, Cai Yi Wang, and Juan M. Elizondo, “Femtosecond Ultraviolet LaserPulse Induced Lightning Discharges in Gases,” IEEE J. Quantum Electron. 31. 599-612(1995).12.M.A. Biondi, “Recombination,” in Principles of Laser Plasmas, G. Bekefi, ed. pp.125-157 (New York,Wiley, 1976)#68045 - $15.00 USD Received 17 February 2006; revised 9 May 2006; accepted 10 May 2006 (C) 2006 OSA29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 491513. Quanli Dong, Fei Yan, Jie Zhang, Zhan Jin, Hui Yang, Zuoqiang Hao, Zhenglin Chen, Yutong Li, ZhiyiWei, and Zhengming Sheng, “The measurement and analysis of the prolonged lifetime of the plasmachannel formed by short pulse laser in air,” Acta Physica Sinica 54, 3247-3250 (2005).14. Jiansheng Liu, Zuoliang Duan, Zhinan Zeng, Xinhua Xie, Yunpei Deng, Ruxin Li, and Zhizhan Xu,“Time-resolved investigation of low-density plasma channels produced by a kilohertz femtosecond laser inair,” Phys. Rev. E 72, 026412 (2005).The generation of light filaments in air has attracted broad interest [1-4] due to their applications for lightning protection [5-6] and atmospheric remote sensing [7]. The filaments remain stable over tens of meters or more, which is much longer than the beam’s Rayleigh distance [1-3]. This self-guiding effect has been attributed to a dynamic balance between beam self-focusing (owing to the optical Kerr effect) and defocusing (owing to medium ionization). A high degree of ionization as well as a long lifetime of light filaments is preferred in practical application. Recent research on the lifetime of light filaments reported that the lifetime of a light filament could be enhanced by bringing in a second long-pulse laser after a femtosecond laser pulse mainly due to the optical detachment effect [8-10]. The electron density owing to the optical detachment effect maintains itself at about 12313310~10cm cm −− [9]. We hope to further increase the degree of ionization during the total lifetime of a plasma channel.In our experiment, we applied a high voltage electrical field in the plasma channel induced by a femtosecond laser pulse in air. Results show that the lifetime of the plasma channel had been prolonged and also the degree of ionization increased. The lifetime of the plasma channel reaches about 60 ns with a field of about 350kV/m. We investigated the variation of the lifetime of the plasma channel with the increase in electric field. In addition, we brought in a second femtosecond laser pulse and found that the lifetime of the filament can reach 200 ns with a delay of 60 ns between the first and second pulse. Finally, the lifetime of plasma channel was enhanced to 350 ns by using four sequential laser pulses, which proves the feasibility of prolonging the lifetime of plasma by employing multiple laser pulses.The experiments were performed with a 10-Hz chirped-pulse amplification Ti-sapphire laser system. A plasma channel was produced by a 2-mJ, 100-fs chirped laser pulse at 790 nm with a focusing lens of f=50 cm. An electrical field which can be adjusted in a range of 0-350kV/m was applied along the plasma channel. The experimental arrangement is shown in Fig. 1. The configuration of the electrodes here for the high voltage is sharp-point. The distance between two electrodes is about 3 cm. The variation of the electrical signals in the channel indicates the decay of electron density. And Electron decay rate is directly related to the length of plasma’s life. Therefore, we measure the lifetime of the plasma channel by detecting voltage from probe c in the channel.Fig. 1. Experimental setup; Electrodes a, b, and probe c are set close to the path of the plasmachannel induced by femtosecond laser pulse.#68045 - $15.00 USD Received 17 February 2006; revised 9 May 2006; accepted 10 May 2006(C) 2006 OSA 29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 4916We have measured the electrical signals when the fields are 0, 250, and 350kV/m respectively. Meanwhile, through a longitudinal diffraction detection method [14], the initial electron density was estimated at about 17310cm −and the diameter of the plasma channel was about 100m μ. The visible length of the plasma channel was over 4 cm.As shown in Fig. 2(a), the decay time of the electrical signal (defined as the duration lasting from the maximum value to 5% of the maximum value), increased by about 3 folds when the electrical field increased to 350 kV/m (dash-dotted line c). As we expected, the variation of the electrical signals in the channel showed that the lifetime of the plasma channel was prolonged when the electrical field increased. On the other hand, the solid line in Fig. 2(b), resulting from a theoretical model, which will be discussed later based on Eq. (1)-(3), depicts the evolution of electron density in the absence of an electrical field. We calculated that within 20 ns the electron density would be expected to fall to 31410−cm . Here, the initial electron density in our calculation was of the same order magnitude as the measurement in our experiment (17310cm −). Therefore, we expected that within the same 20 ns the electron density in the plasma would remain above 31410−cm . We regard this level as an indication of the lifetime of a plasma channel. In Fig. 2(a), compared to line a, line b and c indicate increased lifetimes of 40 and 60 ns respectively. Our experiment results show that an electrical field added in the plasma channel can affect the characteristics of the plasma and prolong the lifetime of the plasma channel.#68045 - $15.00 USD Received 17 February 2006; revised 9 May 2006; accepted 10 May 2006(C) 2006 OSA 29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 4917Fig. 2. (a) Measured electrical signals (solid line a, dashed line b, and dash-dotted line ccorrespond to electrical fields of 0V/m, 250kV/m, 350kV/m respectively); (b) Theoreticalcalculation with initial condition that 173210e n cm −=×.In order to further extend the lifetime of the plasma channel, we added a second femtosecond laser pulse with the external electrical field still in place. The delay between the two laser pulses was adjusted and the corresponding lifetime of the plasma channel is measured as shown in Fig. 3 and Fig. 4. As we can see in Fig. 3, the lifetime is prolonged to about 150 ns when the delay between two pulses is 40 ns. With a delay of 60 ns, the lifetime increases to 200 ns. As shown in Fig. 4, further increase in delay (100 ns) no longer leads to further extension of the lifetime. This is because the distance between the two laser pulses is so long that the interaction between them is less pronounced than in situations with shorter delay time.#68045 - $15.00 USD Received 17 February 2006; revised 9 May 2006; accepted 10 May 2006(C) 2006 OSA 29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 4918A multi-pulse scheme is employed here to reach a longer lifetime. In our experiment, we added three more laser pulses to the original laser pulse with a delay between two consecutive pulses at about 70 ns. This was done to obtain an optimal effect on the lifetime. These multiple laser pulses were generated by passing a main laser pulse through beam splitters and setting long-range fixed delays. The electrical field remained at about 350kV/m. The energy of the original pulse was 0.4 mJ and those of the later three laser pulses are all about 0.1 mJ ±0.1 mJ due to long-range propagation. The measured electrical signal is shown in Fig. 5 with a total lifetime of about 350 ns. As we can see, the signal caused by subsequent pulses is not as intense as in the double-pulse experiments conducted. This is due to the relatively low energy of later pulses. According to our double-pulse experimental results, we can expect that with relatively high energy of each later pulse at about 0.4 mJ, the lifetime of the plasma channel can be increased longer than what we acquired in Fig. 5. Therefore, we can conclude that a multi-pulse scheme with an electrical field added is efficacious for the extension of the lifetime of the plasma channel.-0.010.000.010.020.030.040.050.06e l e c t r i c a l s i g n a l (a .u .)t(ns)Fig. 3. Electrical signals in double-pulse scheme. The energies of two pulses with the delay of20 ns are 0.5 mJ and 0.4 mJ respectively. The energies of two pulses with the delay of 40 ns arealso 0.5 mJ and 0.4 mJ respectively. #68045 - $15.00 USD Received 17 February 2006; revised 9 May 2006; accepted 10 May 2006(C) 2006 OSA 29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 4919Fig. 4. Electrical signals in double-pulse scheme. The energies of two pulses with the delay of60 ns are 0.5 mJ respectively. The energies of two pulses with the delay of 100 ns are 0.3 mJrespectively.Fig. 5. Electrical signal in four-pulse scheme. The energy of the first pulse is 0.4 mJ, and theenergies of later pulses are all about 0.1 mJ. The delay between two contiguous pulses is 70 ns.The main mechanisms involved in the decay process of the plasma channel in a highelectrical field include the photo-ionization, impact ionization, dissociative attachments of electrons to oxygen molecules, charged particle recombination, detachments of electrons byion-ion collision, and electron diffusion. Among these effects, the attachment of electrons to oxygen molecules is detrimental to the lifetime of the plasma channel. The effect of#68045 - $15.00 USD Received 17 February 2006; revised 9 May 2006; accepted 10 May 2006 (C) 2006 OSA29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 4920detachments of electrons caused by ion-ion collision is relatively weak compared with the others and thus is omitted in our analysis. And the electron diffusion is a slow process, on the time scale of tens of s μ[11]. And electron generation and plasma formation are on the time scale of ns to s μ. At this time scale, effects from electron diffusion can be neglected. Therefore, we can estimate the lifetime of the plasma channel following the equation of continuity as follows [10，11] p e ep e e e n n n n tn βηα−−=∂∂ (1) p n np p e ep e pn n n n n tn ββα−−=∂∂ (2) p n np e n n n n tn βη−=∂∂ (3) where e n , p n , n n are electron density, positive ion density, and negative ion density in air respectively. α is the impact ionization coefficient. ηis the attachment rate. Initial conditions for theoretical analysis is that 173210e n cm −=×, 173210p n cm −=×, 0n n =.Through our simulation, αand ηin different electric fields did not exert a noticeable effect on the lifetime of a plasma channel. Therefore, we expect that ep βand np βmay play a role in extending the lifetime when an external electrical field is added.Without considering the effect of external electric field, a general expression of electron-ion recombination coefficient ep βas a function of electron temperature Te is [11, 12]:3120.39123110.702212(/) 2.03510,()(/) 1.13810,()0.790.21ep m s Te e N m s Te e O βββββ−−−+−−−+=×−=×−=+ (4)We take np ep ββ= in our calculation since the ion-ion recombination coefficient np β is of the same order of magnitude as the electron-ion recombination coefficient ep β.The theoretical simulation of the lifetime of the plasma channel is shown in Fig. 6. As line a, b and c shown, the lifetime of the plasma channel is prolonged from 20 ns to 60 ns as the dissociative recombination coefficient ep βand np β decrease.Potential energy curves play a role in dissociative recombination. In a favorable potential curve crossing case, a sharper falloff in this coefficient than 0.39Te −and 0.70Te −will occur with increasing incident electron energy [12]. When the external electrical field is added along the plasma channel, the incident energy of electrons will be increased. Meanwhile, Te can be assumed to thermalize at the same ambient air temperature as the gas molecules [11]. Because potential energy curves will change due to the external electrical field, we expect that a favorable potential curve crossing may exist in this case. And this can lead to a quicker falloff in ep βand np β, and corresponding extension in the lifetime as electron energy increases, as we can see from the comparison of line a, b and c shown in Fig. 6.#68045 - $15.00 USDReceived 17 February 2006; revised 9 May 2006; accepted 10 May 2006(C) 2006 OSA 29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 4921Fig. 6. Theoretical simulation with 417.410s α−=× and 712.510s η−=× [11]; Solid line a,dashed line b and dash-dotted line c correspond to different dissociative recombinationrates 1332.210/m s −×, 1330.810/m s −× and 1330.310/m s −× respectively.Similarly, in double-pulse and multi-pulse case, the dissociative recombination rate can decline more intensively than the case without an external electrical field and this will thus lead to an extension of the lifetime of the plasma channel. Moreover, the addition of the second and later pulses will again cause a large number of electrons due to photo-ionization [13]. With these extra electrons, the lifetime of the plasma channel will further extend.As a conclusion, characteristics of the lifetime of the plasma channel are investigated by adding an external electrical field and also extra laser pulses. The lifetime increases by 3 folds when the external electrical field is about 350kV/m in our experiment. We expect that a favorable crossing case may exist when an external electrical field is in place, and this can lead to a corresponding growth in the lifetime of the plasma channel. In addition, the lifetime of plasma channel is greatly enhanced to 350 ns by using four sequential intense 100fs (FWHM) laser pulses with the external electrical field (350kV/m). Therefore, we conclude that a multi-pulse scheme with an external electrical field added is feasible for greatly prolonging the lifetime of a plasma channel. This research is supported by a Major Basic Research project of the Shanghai Commission of Science and Technology, the Chinese Academy of Sciences, the Chinese Ministry of Science and Technology, and the Natural Science Foundation of China. #68045 - $15.00 USD Received 17 February 2006; revised 9 May 2006; accepted 10 May 2006(C) 2006 OSA 29 May 2006 / Vol. 14, No. 11 / OPTICS EXPRESS 4922。

互相关干扰下的MIMO雷达自适应脉冲压缩方法

K
=0
0 ≤ i ＜ K， m≠n
k = －i + 1
∑
s m（ k ） s n （ k + i ） = 0
*
－ K ＜ i ＜ 0， m≠n
当发射信号满足正交条件时，式（ 7 ）中的第 2 项可以忽略．但实际中的 MIMO 雷达发射波形无法作到完全正在现有的 MIMO 雷达波形优化工作中，信号的旁瓣电平依然很高，这样造成传统的脉冲压缩对发射信号交，的分离效果会很差，需要寻求能有效抑制距离旁瓣的脉冲压缩滤波方法．
MIMO）雷达是近年来学术界提出的一种新体制雷达，多输入多输出（ Multiple Input Multiple Output，在目［1 ］标跟踪和检测、目标参数估计和成像等领域中，其性能优于传统雷达． MIMO 雷达可分为两类：分布式 MIMO 雷达和集中式 MIMO 雷达．分布式 MIMO 雷达通过空间分集，提高了对目标的检测和估计性能，它要求阵元具有较大的间隔．而集中式 MIM0 雷达仍采用传统阵列构型，通过发射多信号提高了信号处理自由度，从而提高了空域信号处理能力．对于集中式 MIMO 雷达，由于其发射信号的互相关性，必然导致雷达回波信号不仅存在噪声的叠加，还存在来自回波信号之间的互干扰，从而提高了旁瓣，影响了目标的检测性能．现［23 ］．由于不可有的解决方法主要是通过波形优化方法，将 MIMO 雷达距离分辨率引入目标函数来降低旁瓣能得到一组在各种环境的距离延迟下都完全正交的发射信号，因此，仅仅依靠波形设计无法满足 MIMO 雷达的探测要求，对于旁瓣的抑制与目标的检测将更加依赖于信号处理过程． 46］提出了改进的脉冲压缩方法— — —递归最小均方误差针对经典脉冲压缩匹配滤波的缺陷，文献［（ Reiterative Minimum MeanSquare Error， RMMSE ）算法．这种方法在高斯噪声背景下，对 P3 码信号获得了较低的距离旁瓣，提高了对邻近距离小目标的检测能力．为获得更好的目标检测性能，笔者针对单基地 MIMO

一种简化计算的S型加减速NURBS插补算法

一种简化计算的S型加减速NURBS插补算法覃珍莹;赵东标;周迪琪【摘要】针对目前NURBS曲线插补中加减速控制方法不足的问题,实现了加工过程中进给速度的平滑过渡,提出了一种新的NURBS曲线插补方法,包括速度规划和实时插补两个方面.速度规划采用了一种基于曲率自适应的简化计算的S型加减速方法,并结合“双向插补”的思想实时预测减速点,防止产生过大的弓高误差;实时插补则利用Muller插值和Newton迭代法计算了下一周期的插补参数,进而求出了下一时刻到达的空间坐标点.最后与已有插补方法进行了仿真分析比较.研究结果表明,该方法能保证加速度连续和加加速度有界,有效减少弓高误差和进给速度波动,提高机床运行的平稳性.%Aiming at the deficiency of acceleration and deceleration control method in NURBS curve interpolation,and to realize the smooth transition of fee&ate during the manufacturing process,a new method of NURBS interpolation was proposed,including feedrate planning and real time interpolation.In feedrate planning,a new simplified calculation method of s-shaped acceleration and deceleration based on curvature adaptive algorithm was adopted,and to prevent excessive chord error,the idea of bidirectional interpolation to predict the deceleration point in real time was also used.In real time interpolation,Muller interpolation method and Newton iterative method were utilized to calculate the interpolation parameter of the next period,and the space coordinates of the next period was given as well.Finally,the algorithm was compared with the existing interpolation methods for simulation analysis.The results indicate that this method can guarantee the continuityof acceleration and the boundedness of jerk,effectively reduce the chord error and feedrate fluctuation,and improve the stability of machine tool operation.【期刊名称】《机电工程》【年(卷),期】2017(034)003【总页数】5页(P219-223)【关键词】非均匀有理B样条;速度规划;实时插补;牛顿迭代法【作者】覃珍莹;赵东标;周迪琪【作者单位】南京航空航天大学机电学院,江苏南京210016;南京航空航天大学机电学院,江苏南京210016;南京航空航天大学机电学院,江苏南京210016【正文语种】中文【中图分类】TH161;TP24NURBS曲线以统一的数学函数描述了不同的空间曲线和曲面，表达能力强且直观性好，在SIMENS、FANUC等一些国外高档数控系统中已经得到了广泛应用，但在国内数控加工领域，NURBS曲线插补技术的研究还有待改进。

添加植物源化合物(PHY)或自溶酵母(AY)可改善非泌乳奶牛亚急性瘤胃酸中毒期间的瘤胃生物胺(BA)

添加植物源化合物(ＰＨＹ)或自溶酵母(ＡＹ)可改善非泌乳奶牛亚急性瘤胃酸中毒期间的瘤胃生物胺(ＢＡ)和脂多糖浓度(二)严毅梅(译)图２㊀该图显示添加６５％或不加入添加剂(ＣＯＮ)㊁添加植物源化合物(ＰＨＹ)或自溶酵母(ＡＹ)的条件下ꎬ奶牛血液中的氨基酸(Ａ)㊁溶血磷脂酰胆碱和磷脂酰胆碱(Ｂ)的浓度ꎮｌｙｓｏＰＣ＝溶血磷脂酰胆碱ꎻＰＣ＝磷脂酰胆碱ꎻａ＝酰基ꎻａａ＝二酰基ꎻａｅ＝酰基烷基ꎮ不同的字母表示饲料添加剂导致的差异显著(ａꎬｂꎬＰ<０.０５)或存在差异趋势(ｙꎬｚ０.０５<Ｐ<０.１)ꎮ图３利用偏最小二乘法判别分析血浆代谢组(Ａ)ꎮ三维评分图区分了喂食全价饲料(基础日粮)或６５％精料(ＳＡＲＡ)的奶牛的代谢谱ꎮ根据设计的评分标准确定１５个最具影响力的变量ꎬ根据偏最小二乘法判别分析它们ꎮ(ｂ)Ｈ１＝己糖的总和ꎻＰＣ＝磷脂酰胆碱ꎻＡＡ＝二酰基ꎻＡＳＴ＝天冬氨酸氨基转移酶ꎮ颜色版本在线可用ꎮ图４㊀在ＳＡＲＡ发生期间ꎬ在喂食奶牛全价饲料(基础日粮)或６５％精料(ＳＡＲＡ)和不加入添加剂(对照组)时ꎬ利用层次聚类分析法分析不同瘤胃液和血液代谢物ꎬ以及低于ＳＡＲＡ阈值的复杂的ｐＨ值和全价饲料和谷物摄入量ꎮ测定植物化合物(ＰＨＹ)ꎬ或自溶酵母(ＡＹ)ꎮ在ＳＡＲＡ期间ꎬ细胞是根据样品中的浓度来着色的ꎮ暗红色代表高水平ꎬ蓝色显示低水平ꎬ灰色细胞显示中间水平ꎮ２个变量之间的相似性用分支高度表示ꎮａ＝酰基ꎻＡＤＭＡ＝不对称二甲基精氨酸ꎻα－ＡＡＡ＝α－氨基己酸ꎻＣ＝肉碱ꎻＧＧＴ＝γ－谷氨酰转移酶ꎻＯＨ＝羟基ꎻＰＣ＝磷脂酰胆碱ꎻａｅ＝酰基－烷基ꎻａａ＝二酰基ꎻＳＭ＝鞘磷脂ꎮ彩色版本在线可用ꎮ㊀㊀如图２Ａ所示ꎬ与对照组相比ꎬ(即精氨酸㊁天冬酰胺㊁异亮氨酸㊁亮氨酸㊁赖氨酸㊁蛋氨酸㊁苯丙氨酸㊁苏氨酸和酪氨酸ꎬＰɤ０.０９)相比ꎬ补充ＰＨＹ导致氨基酸增加到３４％ꎮＰＨＹ增加不对称二甲基精氨酸(Ｐ＝０.０５)ꎬ与此同时ꎬ导致肌氨酸酐降低达９％(Ｐ＝０.０６)ꎮ在与对照组相比ꎬ补充ＰＨＹ的奶牛体内的乙酰肉毒含量较高(Ｃ５ꎬＣ１４－１)或更低(Ｃ１８:１)(Ｐ<０.１０)ꎮ如图２Ｂ所示ꎬ与对照组(Ｐɤ０.１０)相比ꎬＰＨＹ增加了溶血磷脂酰胆碱(其中ａ＝酰基)Ｃ１４:０和溶酶体Ｃ１６:０和几个ＰＣꎮ此外ꎬＰＨＹ增加ＳＭ(ＯＨ)Ｃ２２－１和ＳＭＣ１６:０ꎬ降低ＳＭＣ２２:３(Ｐ<０.１０)ꎮ当日粮中添加ＡＹ时ꎬ氨基酸中的谷氨酰胺含量呈下降的趋势(Ｐ＝０.０９)ꎬ而色氨酸含量则相反(Ｐ＝０.０８)ꎮ与对照组相比ꎬ肌氨酸和α－氨基己酸呈下降趋势(Ｐɤ０.０８)ꎬ而补充ＡＹ导致ＰＣａａＣ４０:６(其中ａａ＝二酰基)组低于其他组(Ｐ＝０.１０)图５在ＳＡＲＡ发生期间ꎬ在喂食奶牛全饲料(基础日粮)或６５％的精料(ＳＡＲＡ)和不加入添加剂(对照组)时ꎬ补充植物化合物(ＰＨＹ)ꎬ或自溶酵母(ＡＹ)之时ꎬ测定低于ＳＡＲＡ阈值的复杂的ｐＨ值和全价饲料和谷物摄入量ꎬ以确定不同瘤胃液与血液代谢物的相关性ꎮ利用不同浓度水平生成斯皮尔曼相关系数的热图ꎮ红色表示正相关系数ꎬ蓝色表示负系数ꎮＡＤＭＡ＝不对称二甲基精氨酸ꎻａ＝酰基ꎻα－ＡＡＡ＝α－氨基己酸ꎻＣ＝肉碱ꎻＧＧＴ＝γ－谷氨酰转移酶ꎻＯＨ＝羟基ꎻＰＣ＝磷脂酰胆碱ꎻａｅ＝酰基烷基ꎻａａ＝双酰基ꎻＳＭ＝鞘磷脂ꎮ彩色版本在线可用ꎮ㊀㊀为了说明不同喂养阶段之间数据的差异ꎬ进行ＰＬＳ－ＤＡ分析ꎬ本结果覆盖了９７.４％的所观测的样本组中前三个主要组分ꎬ其中代谢物之间的变化主要可由组分１解释ꎬ而无法由组分２和３解释(图３Ａ)ꎮＰＬＳ－ＤＡ评分图显示ꎬ与基础日粮不同ꎬ而且ＳＡＲＡ期间吃ＰＨＹ的奶牛比对照组奶牛更接近基准ꎮ此外ꎬ相比于吃ＰＨＹ或ＡＹ的牛ꎬ对照组奶牛的数据相近ꎮ根据投影分数选择ＰＬＳＳ－ＤＡ模型中最有影响的变量(图３Ｂ)ꎮ该程序可区别最重要的造成对照组和添加组之间的不同的变量ꎮ因此ꎬ己糖㊁甘氨酸㊁胆固醇和精氨酸的总和是最重要的ꎮ与此同时ꎬ几个ＰＣ和ａａ有助于区分这些不同ꎮ３.３㊀瘤胃与血液代谢物㊁瘤胃ｐＨ值及摄食量之间的关系为了显示瘤胃和血液代谢物浓度的关系和差异ꎬ我们使用ＨＣＡ和热图表示ꎮ图４中的聚类热图显示了集群对应相似程度不同ꎬ数量不同的代谢物ꎮ利用热图上颜色强度的变化来表示与不同饲料和处理方式造成的相关反应的各变量ꎮ在热图的顶部附近放置具有较高相似度的变量ꎮＨＣＡ显示存在一个子簇ꎬ它由一组由若干ＰＣ㊁ＳＭ(ＳＭＯＨＣ２２:２ꎬＳＭＣ１６:０)㊁Ｃ１４:１㊁溶血磷脂酰胆碱Ｃ１６:０㊁胆固醇和饲料摄取量的数据组成ꎮ与ＳＡＲＡ饲料相关的另一个子簇包括若干瘤胃ＢＡ(吡咯烷㊁组胺㊁乙醇胺)㊁ＬＰＳ㊁ＳＭ(ＳＭＣ２２:３ꎬＳＭＣ２０:２)㊁Ｃ１８:１㊁谷物摄取以及从ＳＡＲＡ阈值的ｐＨ值下降持续的时间段ꎮ另一个ＨＣＡ的子簇表示ａａ的构成ꎮＨＣＡ的一个显著特征是ꎬ代谢产物位于顶簇(ｉ.ｅ.ꎬｆｒｏｍＰＣａａＣ３４:２ｔｏｌｙｓｏＰＣａａＣ１６:０)这些代谢物因导致ＳＡＲＡ的饲料而减少ꎬ而对于第二簇则相反ꎮ有趣的是ꎬ新陈代谢物的减少属于第一簇ꎬ但喂食ＰＨＹ(即ꎬ奶牛编号２和４)或ＡＹ(即ꎬ奶牛编号２㊁３和４)的一些奶牛表现的并不明显或较不明显ꎮ第三个子簇表示变量集(即从苯丙氨酸到色氨酸)ꎬ热图的底部显示出更多可变的响应ꎮ对饲料添加剂影响的所有参数进行相关模式分析(图５)ꎮ由ＰＣ㊁ａａ㊁胆固醇和饲料摄取量组成的聚类与ＬＰＳ㊁瘤胃ＢＡ㊁谷物摄取量以及低ｐＨ条件下的时间呈负相关ꎮ４㊀讨㊀论４.１㊀间歇性ＳＡＲＡ挑战的影响本研究的主要目的是测定牛ＳＡＲＡ导致瘤胃液中的ＬＰＳ和ＢＡ的浓度变化以及血浆代谢组的变化ꎮ在本研究中ꎬ使用不产乳的母牛以排除所有泌乳周期影响血液代谢组的可能ꎮ本研究分析饲养模型ꎬ旨在使日粮诱导ＳＡＲＡ和由此引起的瘤胃紊乱对奶牛系统代谢的影响定量化ꎬ同时排除泌乳效应ꎮ我们发现ꎬ从全价饲料到高浓度日粮明显增加了ＬＰＳ和ＢＡ的浓度ꎮ此外ꎬ我们的发现表明ꎬＳＡＲＡ显著破坏了血液代谢体ꎬ包括改变氨基酸和脂质代谢途径ꎬ如氨基酸㊁溶血磷脂胆碱㊁ＰＣ和ＳＭ的减少ꎮ在设计好的ＳＡＲＡ期间ꎬ因为高浓度饲料与增加拟杆菌的死亡和溶解有关ꎬ在瘤胃中发现大多数革兰氏阴性细菌处于ｐＨ低的条件下ꎬ所以瘤胃中的革兰氏阴性细菌的细胞壁成分(ＧＮＢ) ＬＰＳ的大大增加ꎬ(Ｋｈａｆｉｐｏｕｒ等ꎬ２００９ꎻＭａｏ等ꎬ２０１３)ꎮ在ＧＮＢ中ꎬ已知大肠杆菌的ＬＰＳ比在奶牛瘤胃中发现的其它如埃氏巨型球菌㊁普雷沃菌和拟杆菌的ＧＮＢ毒性更大ꎬ(Ｚｅｂｅｌｉ和Ｍｅｔｚｌｅｒ－Ｚｅｂｅｌｉꎬ２０１２)ꎮ更具体地说ꎬ据报道ꎬ大肠杆菌衍生的ＬＰＳ是瘤胃中的主要毒性化合物ꎬ并对瘤胃上皮和奶牛的整体健康造成有害影响(Ｋｈａｆｉｐｏｕｒ等ꎬ２００９ꎻＭａｏ等ꎬ２０１６)ꎮＢＡ与瘤胃中的ＬＰＳ相互作用ꎬ以前已经提出了ＬＰＳ的毒性(Ａｍｅｔａｊ等ꎬ２０１０ꎻＺｅｂｅｌｉ和Ｍｅｔｚｌｅｒ－Ｚｅｂｅｌｉꎬ２０１２)ꎮ本研究揭示了ＬＰＳ与乙醇胺㊁组胺㊁吡咯烷㊁亚精胺以及ｐＨ低于ＳＡＲＡ阈值的持续时间呈正相关ꎮ一般来说ꎬＳＡＲＡ期间ＢＡ的增加归因于瘤胃ｐＨ的降低ꎮ瘤胃的ｐＨ值降低至酸中毒水平ꎬ有助于产生ＢＡ(主要是如链球菌和乳酸杆菌之类的导致碳水化合物发酵的细菌)的微生物生长以及细菌ＡＡ－脱羧酶的活性的增强ꎮ(Ｓｔｒａｕｂ等ꎬ１９９５ꎻＫｈａｆｉｐｏｕｒ等ꎬ２００９ꎻＷａｎｇ等ꎬ２０１３)ꎮ虽然它们的病理生理功能尚未完全了解ꎬ经讨论认为ꎬＢＡ减少饲料摄取和减少网状细胞运动(ＶａｎＯｓ等ꎬ１９９５ꎻＰｈｕｎｔｓｏｋ等ꎬ１９９８)ꎬ以及它们对瘤胃上皮产生有害影响ꎬ如局部炎症的发生和屏障功能的损害(Ｚｅｂｅｌｉ和Ｍｅｔｚｌｅｒ－Ｚｅｂｅｌｉꎬ２０１２)ꎮ因为据推测组胺在蹄叶炎(Ｂｅｒｇｓｔｅｎꎬ２００３)和酸中毒的发病机制中起作用ꎬ所以认为它是主要的毒性因素之一(Ａｓｃｈｅｎｂａｃｈ和Ｇäｂｅｌꎬ２０００)ꎮ在我们的研究中ꎬＳＡＲＡ１期间比ＳＡＲＡ２期间瘤胃液中组胺㊁乙醇胺和吡咯烷的浓度显著的高ꎮ在ＳＡＲＡ１期间ꎬ网织红细胞ｐＨ值降幅最大(Ｋｒöｇｅｒ等ꎬ２０１７)而相应进食阶段乳酸杆菌的丰度增加(Ｎｅｕｂａｕｅｒ等ꎬ２０１８)ꎮ然而ꎬ在目前的研究中ꎬＳＡＲＡ期间瘤胃液中ＢＡ的增加并没有反映在血液中ＢＡ的增加上ꎮ在进入体内系统循环时ꎬ瘤胃上皮吸收不良或因肝脏的甲基化或氧化导致快速代谢可能导致ＳＡＲＡ期间瘤胃液中ＢＡ的增加ꎬ但血液中ＢＡ并未增加ꎮ这也解释了为什么在我们的研究中ꎬ有几种ＢＡ在外周血中无法检测到(Ｇｏｔｈꎬ１９７４ꎻＢｒｅｎｔꎬ１９７６)ꎮ虽然对ＢＡ和细菌内毒素的研究已经非常深入ꎬ但ＢＡ与消化道中的ＬＰＳ的关系以及对系统代谢的可能影响仍不清楚ꎮ我们利用多变量分析揭示了瘤胃液中几种有害化合物(即ＬＰＳ㊁组胺㊁乙醇胺㊁吡咯烷㊁亚精胺)的浓度与血液中ＡＡ㊁ＰＣ㊁溶血磷脂胆碱和ＳＭ的浓度之间的存在负相关关系ꎬ表明瘤胃液中的这些有毒物质影响氨基酸和脂质代谢的代谢途径ꎮ导致ＳＡＲＡ的饲料显著减少几种氨基酸与以前的研究报告一致ꎬ受到ＬＰＳ(Ｈｕｍｅｒ等ꎬ２０１８)外部影响的奶牛患多种围产期疾病(包括蹄叶炎)(Ｈａｉｌｅｍａｒｉ￣ａｍ等ꎬ２０１４ａ)ꎮ其根本机制可能是由于需要氨基酸为免疫细胞提供能量而导致蛋白质分解代谢增加ꎬ最终导致几种氨基酸的消耗增加ꎬ如精氨酸或色氨酸(ＬｅＦｌｏｃ'ｈ等ꎬ２００４ꎻＨａｉｌｅｍａｒｉａｍ等ꎬ２０１４ａ)ꎮ除了氨基酸减少ꎬＳＡＲＡ也导致ＰＣ㊁溶血磷脂胆碱和ＳＭ的显著下降ꎮ以前曾报告过瘤胃ＰＣ也减少(Ｓａｌｅｅｍ等ꎬ２０１２)ꎬ原生动物是瘤胃液中ＰＣ的主要来源(Ｊｏｕａｎｙ等ꎬ１９８８ꎻＧｏａｄ等ꎬ１９９８ꎻＫｈａｆｉｐｏｕｒ等ꎬ２００９)ꎬ在ｐＨ值低期间ꎬ原生动物数量减少ꎬ从而导致ＰＣ减少ꎮ因为磷脂酶Ａ２导致ＰＣ水解产生溶血磷脂胆碱ꎬ所以ＰＣ的减少可能导致溶血磷脂胆碱减少ꎬ(Ｈａｉｌｅｍａｒｉａｍ等ꎬ２０１４ｂ)ꎮ此外ꎬ奶牛的乳房的内部受到来自大肠杆菌的ＬＰＳ影响ꎬ或奶牛正在经历疾病(Ｏ２６:Ｂ６)ꎬ先前已报告在这种情况下的奶牛的血浆溶血磷脂胆碱降低(Ｈａｉｌｅｍａｒｉａｍ等ꎬ２０１４ｂꎻＨｕｍｅｒ等ꎬ２０１８)ꎮ然而ꎬＰＣ通常与三酰甘油有关(Ｇｒｕｆｆａｔ等ꎬ１９９６)ꎬ因为醋酸是一种主要的反刍动物的胆固醇合成前体ꎬ(Ｎｅｕｂａｕｅｒ等ꎬ２０１８)而喂食高浓度饲料导致碳水化合物发酵降低醋酸的产量有关ꎬ所以在喂食高浓度饲料的奶牛中ꎬ这种减少可能是常见的现象(Ｌｉｅｐａ等ꎬ１９７８)ꎮ此外ꎬＳｍ是低密度脂蛋白的牛磷脂的一部分(Ｎｉｌｓｓｏｎ和Ｄｕ￣ａｎꎬ２００６)ꎮＰＣ㊁ＳＭ和胆固醇的表现出强的正相关性ꎬ这些在ＨＣＡ的一个子簇中ꎮ４.２㊀饲料添加剂的效果本研究的第二个目的是研究喂食奶牛高浓度饲料时饲料添加剂对瘤胃ＬＰＳ和ＢＡ的影响ꎬ以及血液代谢状况的影响ꎮ总体而言ꎬ饲料添加剂对瘤胃ＬＰＳ和ＢＡ的大部分影响发生在ＳＡＲＡ１期间ꎬ由于在ＳＡＲＡ１期间ꎬ富含浓缩物的饲料对ｐＨ值和瘤胃微生物群落的影响大ꎬ而在ＳＡＲＡ２期间ꎬ奶牛已经适应了这种状况(Ｋｒöｇｅｒ等ꎬ２０１７ꎻＮｅｕｂａｕｅｒ等ꎬ２０１８)ꎮ日粮中添加ＰＨＹ的高浓度饲料可以抵消ＬＰＳ㊁ＢＡ浓度升高和血液代谢组变化ꎮ对ＬＰＳ和ＢＡ的影响在ＳＡＲＡ１期间最明显ꎬＬＰＳ和总ＢＡ分别减少４３％和２５％ꎬ这与先前的研究一致ꎬ表明ＰＨＹ在低ｐＨ值条件下最有效(Ｃａｒｄｏｚｏ等ꎬ２００５)ꎮ此外此饲料除了减轻ＬＰＳ的影响ꎬ而且ꎬ据推测组胺与酸中毒和蹄叶炎的发病机制相关ꎬ因此组胺的大量减少也有望减轻高浓度饲料喂养的负面后果ꎮ此外ꎬ据推测ꎬ组胺浓度升高会加剧瘤胃酸中毒的严重性(Ｚｈａｎｇ等ꎬ２０１７)ꎮ据先前已经报道(Ｚｅｂｅｌｉ等ꎬ２０１１)ꎬ在ＳＡＲＡ１期间ꎬ因为瘤胃的ＬＰＳ浓度和血浆胆固醇之间成反比关系ꎮ所以添加ＰＨＹ的奶牛的胆固醇浓度的增加ꎬ而ＬＰＳ浓度的降低ꎮ由于胆固醇是合成胆汁酸的主要前体ꎬ胆汁酸(Ｐａｒｌｅｓａｋ等ꎬ２００７)产生的增加可解毒和除去ＬＰＳꎬ这可能降低血液胆固醇(Ｅｃｋｅｌ和Ａｍｅｔａｊꎬ２０１６)ꎮ与对照组相比ꎬ胆固醇浓度的增加进一步支持了ＰＨＹ可抵消ＳＡＲＡ期间观察到的奶牛血浆ＡＡ浓度降低的观点ꎬ据报道ꎬ因为低血浆胆固醇与血浆ＡＡ紊乱有关(Ｃｈｉａｒｌａ等ꎬ２００４)ꎮ此外ꎬＰＨＹ可增加胆固醇浓度ꎬ从而对ＳＡＲＡ期间ＰＣ降低起到抵消作用ꎬ这可归因于两者的关系正相关ꎮＰＨＹ诱导的瘤胃ＬＰＳ和ＢＡ的减少以及随后的系统代谢变化可能由不同的机制解释ꎮ首先ꎬ喂食ＰＨＹ的奶牛的ＧＮＢ降低(Ｎｅｕｂａｕｅｒ等ꎬ２０１８)ꎬ这可能有助于降低ＧＮＢ在消化道中释放毒性物质ꎬ因为一些种类的ＧＮＢ是潜在的ＬＰＳ生产者ꎮ与ＰＨＹ对瘤胃ＬＰＳ的作用相一致ꎬ清除ＬＰＳ所需的胆汁酸的产生要求较低导致血胆固醇浓度较高ꎮ此外ꎬＰＨＹ提高了处于ＳＡＲＡ１期(Ｋｒöｇｅｒ等ꎬ２０１７)的奶牛的反刍活动ꎬ这可能增加唾液分泌ꎬ从而可能稀释瘤胃中的ＬＰＳ和ＢＡꎬ或使它们离开瘤胃ꎮ此外ꎬＰＨＹ可通过刺激网状组织㊁皱胃和十二指肠中的化疗敏感性上皮受体来增加网状内皮运动(Ｍａｍａｇｈａｎｉ等ꎬ２０１３ꎻＭｅｎｄｅｌ等ꎬ２０１７)ꎮ因此ꎬ可以推测因为增加的网状内皮运动可促进去除瘤胃中的有害化合物ꎬ也可促进网状组织中的食糜外流ꎮＰＨＹ组中ＢＡ的减少似乎也与ＰＨＹ组中较高的瘤胃ｐＨ有关(Ｋｒöｇｅｒ等ꎬ２０１７)ꎬ如上文所述ꎬ细菌ＡＡ－脱羧酶的活性增加而使瘤胃中的ｐＨ低ꎬ从而增加ＢＡ的合成ꎮ在日粮中添加ＡＹ对ＳＡＲＡ１期间ＢＡ含量有显著影响ꎬ与对照组相比ꎬＢＡ的绝对含量下降３１％ꎮ除了上述减少对组胺的影响起到所预期的积极作用外ꎬ喂食ＡＹ的奶牛体内的乙醇胺㊁甲胺㊁亚精胺和精胺的浓度也降低ꎬ因为这与动物健康相关ꎬ所以这是一个重要发现ꎮ此外ꎬ由于乙醇胺在某些病原体的繁殖中起到关键作用ꎬ所以乙醇胺意味着对人类健康㊁食品安全和环境问题的风险产生影响(Ｌａｗꎬ２０００ꎻＳａｌｅｅｍ等ꎬ２０１２)ꎮ据推测ꎬ由于富含谷物的饲料喂养期间瘤胃微生物群变化引起乙醇胺浓度升高(Ｋｈａｆｉ￣ｐｏｕｒ等ꎬ２００９)ꎬ这加速了瘤胃上皮细胞的翻转率(Ｇｏｏｄｌａｄꎬ１９８１)和ＧＮＢ的细胞溶解(Ｎａｇａｒａ￣ｊａ等ꎬ１９７８ꎻＳａｌｅｅｍ等ꎬ２０１２)ꎮ由于乙醇胺为许多病原体提供了碳源或氮源ꎬ因此这种胺的浓度高可为致病性ＧＮＢꎬ如沙门氏菌㊁肠球菌和大肠杆菌在胃肠道的增殖和定殖铺平道路(Ｓａｌｅｅｍ等ꎬ２０１２ꎻＺｈａｎｇ等ꎬ２０１７)ꎮ甲胺也可能对奶牛造成严重的健康风险ꎬ因为如果被吸收到血液循环中ꎬ甲胺会降解成有毒的代谢物ꎬ如过氧化氢和甲醛(Ｙｕ等ꎬ２００６)ꎮ此外ꎬ预计ＡＹ对ＳＡＲＡ１中亚精胺和精胺的减少将抵消高浓度饲料喂养的负面后果ꎬ因为两种胺在反刍动物中均被血浆胺氧化酶氧化成醛和过氧化氢((Ｂｌａｓｃｈ￣ｋｏ和Ｂｏｎｎｅｙꎬ１９６２ꎻＨöｌｔｔä等ꎬ１９７５)ꎮ据推测ꎬ由于这些氧化产物对真核细胞产生极端毒性及其在氧化应激中的起到的重要作用而导致乳腺炎㊁酮症和脂肪肝等代谢性疾病(Ｒｏｎｃｈｉ等ꎬ２０００)ꎮＡＹ除了影响瘤胃液中ＢＡ的浓度外ꎬ还减弱了高浓度饲料对血浆色氨酸的降低作用ꎮ由于ＬＰＳ或治疗炎症而增加色氨酸分解代谢与先前抑制免疫应答有关(Ｍｅｌｃｈｉｏｒ等ꎬ２００４ꎻＰｌａｔｔｅｎ等ꎬ２００５)ꎮ因此ꎬ很可能是ＡＹ对抗炎症状态ꎮＡＹ对咀嚼活动的刺激使ＡＹ诱导ＢＡ减少ꎬ以前对此已经有报道(Ｋｒöｇｅｒ等ꎬ２０１７)ꎮ总咀嚼时间的增加可能导致唾液分泌增加ꎬ从而对胃肠道中的ＢＡ产生稀释作用ꎮ这可能有助于减少消化道中有害化合物的积累ꎮ这进一步解释了可能是ＡＹ对瘤胃微生物群的影响(Ｎｅｕｂａｕｅｒ等ꎬ２０１８)ꎮ某些酵母细胞壁组分ꎬ如甘露寡糖㊁β－葡聚糖㊁几丁质㊁肽㊁氨基酸和核苷酸ꎬ可以作为有害细菌的高亲和性配体ꎬ并将它们从消化系统中移除而无需附着和定殖(Ｎｏｃｅｋ等ꎬ２０１１ꎻＧａｎｎｅｒ和Ｓｃｈａｔｚｍａｙｒꎬ２０１２)ꎮ事实上ꎬ如我们的同事论文(Ｎｅｕｂａｕｅｒ等ꎬ２０１８)所述ꎬＡＹ减少拟杆菌属ꎬ一个主要的ＧＮＢ(Ｄｗｏｒ￣ｋｉｎꎬ２００６)ꎮ该酵母细胞壁成分还可能结合有害物质并减少它们在消化道的吸收(Ｌｅｉ等ꎬ２０１３)ꎮ有趣的是ꎬＢＡ在ＳＡＡＲ１期间仅当ＡＹ增加最少时ꎬ网状ｐＨ时减少(ＫｒＯｌｅＧｅ等人ꎬ２０１７)ꎮ这表明ＡＹ对网状ｐＨ起到稳定作用ꎬ这似乎是是至关重要的ꎬ它使ＡＹ对ＢＡ产生有利的影响ꎮ５㊀结㊀论喂食高浓度饲料明显提高了瘤胃液中有毒化合物的浓度ꎬ在第一次ＳＡＲＡ期间乙醇胺㊁组胺和吡咯烷显著增加ꎬ同时伴有与脂类和ＡＡ相关的血浆代谢组学途径的不良改变ꎮＰＨＹ和ＡＹ饲料添加剂都抵消了这些变化ꎬ并在瘤胃ｐＨ值低的条件下对主要有毒化合物产生显著影响ꎮ因此ꎬ研究结果提示ꎬ饲料添加剂可能减轻喂食奶牛高浓度饲料的负面后果ꎮ然而ꎬ由于这项研究是在不产乳的母牛中进行ꎬ不得不考虑所得结果不能完全适用于哺乳奶牛的情况ꎮ因此ꎬ需要进一步研究ＳＡＲＡ和饲料添加剂对泌乳奶牛不同泌乳阶段血液代谢组的影响ꎮ(本文译自:Ｅ.ＨｕｍｅｒꎬＩ.ＫｒöｇｅｒꎬＶ.Ｎｅｕｂａｕｅｒꎬｅｔａｌ.Ｓｕｐｐｌｅｍｅｎｔｉｎｇｐｈｙｔｏｇｅｎｉｃｃｏｍｐｏｕｎｄｓｏｒａｕｔｏｌｙｚｅｄｙｅａｓｔｍｏｄｕｌａｔｅｓｒｕｍｉｎａｌｂｉｏｇｅｎｉｃａｍｉｎｅｓ和ｐｌａｓｍａｍｅｔａｂｏｌｏｍｅｉｎｄｒｙｃｏｗｓｅｘｐｅｒｉｅｎｃｉｎｇｓｕｂａｃｕｔｅｒｕｍｉ￣ｎａｌａｃｉｄｏｓｉｓ.ＪｏｕｒｎａｌｏｆＤａｉｒｙＳｃｉｅｎｃｅꎬＶｏｌｕｍｅ１０１ꎬＩｓｓｕｅ１０ꎬＯｃｔｏｂｅｒ２０１８ꎬＰａｇｅｓ９５５９－９５７４.)。

Captiva_EMR-Lipid技术结合UPLC-MS

叶佳明，钟世欢，叶磊海，等. Captiva EMR-Lipid 技术结合UPLC-MS/MS 快速测定牛羊产品中甲苯咪唑及其代谢物的残留量[J].食品工业科技，2024，45（3）：277−283. doi: 10.13386/j.issn1002-0306.2023030304YE Jiaming, ZHONG Shihuan, YE Leihai, et al. Rapid Determination of Mebendazole and Its Metabolites in Cattle and Sheep Products by Captiva EMR-Lipid Technology Combined with UPLC-MS/MS[J]. Science and Technology of Food Industry, 2024, 45(3):277−283. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023030304· 分析检测 ·Captiva EMR-Lipid 技术结合UPLC-MS/MS 快速测定牛羊产品中甲苯咪唑及其代谢物的残留量叶佳明1,2, *，钟世欢1,2，叶磊海1,2，吴余欣1，王　京1（1.浙江公正检验中心有限公司，浙江杭州 310009；2.浙江省食品安全重点实验室，浙江杭州 310009）摘　要：建立了牛羊产品中甲苯咪唑及其代谢物羟基甲苯咪唑、氨基甲苯咪唑的通过式净化-超高效液相色谱-串联质谱测定的分析方法。

样品经0.2%氨化乙腈溶液振荡提取，冷冻离心后，经Captiva EMR-Lipid 小柱净化，直接进样分析。

以安捷伦SB-C 18 色谱柱（2.1 mm×100 mm ，1.8 μm ）进行分离，以0.1%甲酸水和乙腈为流动相进行梯度洗脱，电喷雾正离子（ESI +）模式电离、多反应监测（MRM ）模式进行检测，采用基质匹配标准工作曲线，内标法定量。

2018考研西综复习：重点概念总结(3)

2018考研西综复习：重点概念总结(3)
导读：本文2018考研西综复习：重点概念总结(3)，仅供参考，如果觉得很不错，欢迎点评和分享。

抑制性突触后电位(IPSP)：突触后膜在递质作用下发生超极化，使该突触后神经元的兴奋性下降，这种电位变化称为抑制性突触后电位。

氧热价：某种食物氧化时消耗1L氧锁释放的能量。

血氧饱和度：血红蛋白含氧量占氧容量的百分比。

surfactant：表面活性物质，是由肺泡ii型细胞合成释放的复杂的脂蛋白混合物，以单分子层形式覆盖于肺泡液体表面的一种脂蛋白。

主要成分是二棕榈酰卵磷脂，它分布于肺泡表面，可以降低表面张力的作用。

顺应性：是指在外力作用下弹性组织的可扩张性，容易扩张者，顺应性大，弹性阻力小，不易扩张者，顺应性小，弹性阻力大。

呼吸中枢：指中枢神经系统内产生和调节呼吸运动的神经细胞群。

肺泡通气量：指每分钟吸入肺泡的新鲜空气量(等于潮气量和无效腔气量之差)乘以呼吸频率。

胃肠刺激：由存在于胃肠粘膜层、胰腺内的内分泌细胞的旁分泌细胞分泌，以及由胃肠壁的神经末梢释放的激素，统称为胃肠刺激。

血红蛋白氧容量：100ml血液中血红蛋白所能结合的氧量称为血红蛋白氧容量。

突触：一个神经元与其他神经元相接触，所形成的特殊结构。

基础代谢率(BMR)：在基础状态下单位时间内的能量代谢称为基础代谢率。

内环境的稳态：内环境的各种物理、化学性质是保持相对稳定的，被称为内环境的稳态。

静息电位：细胞在未受刺激时(安静状态下)存在于细胞膜内、外两壁的电位差。

基于FIR滤波的NURBS插补算法研究

基于FIR滤波的NURBS插补算法研究董伯麟;岳云平【摘要】在考虑数控加工精度和加工效率的基础上,针对传统加减速控制中减速点预测不准的缺陷,提出了一种基于级联滤波器的NURBS插补算法.该插补算法根据速度敏感点将要加工的曲线进行分段处理,避免了插补过程中的爬行与过冲,提高了加工质量.基于弓高误差的速度自适应调整使得加工精度一直在允许的范围之内,基于滤波器的进给速度控制方案使速度过渡平稳,提高了插补的效率.最后对提出的NURBS插补算法进行了实验仿真,结果证明该算法的可行性.【期刊名称】《现代机械》【年(卷),期】2015(000)005【总页数】4页(P1-4)【关键词】NURBS;插补算法;滤波器;仿真【作者】董伯麟;岳云平【作者单位】合肥工业大学,安徽合肥230009;合肥工业大学,安徽合肥230009【正文语种】中文【中图分类】TP273传统的数控加工是利用以直代曲对自由曲线曲面进行处理，该方法不仅加工精度低，而且频繁加减速导致加工效率低下，NURBS插补直接对自由曲线曲面进行插补，克服了这些缺点，在提高加工速度和精度等方面具有显著的效果。

因此，NURBS插补技术是数控技术研究的重要方向。

Bedi等[1]提出等参数算法，算法虽然简单，但忽略NURBS曲线一维参数与三维轨迹空间的映射并非等比例线性变化的因素，带来速度波动问题。

Shpitalni等[2]采用泰勒展开法实现了参数的密化，但加工轮廓的误差没有得到有效控制。

Yeh等[3]提出了速度自适应算法，保证了加工过程中的弓高误差。

文献[4-5]引入了加减速控制。

但这些算法都是通过前瞻计算获得加减速区域的弧长，根据弧长来确定加减速的参数区间，弧长的不精确性会产生速度偏差。

文献[6]在插补算法中引用了滤波技术，但是在滤波之前还要进行T型加减速规划。

本文设计了一种基于级联滤波器的NURBS插补算法。

该算法利用滤波技术对速度进行S型曲线加减速规划，避免了减速点预测不准产生的加工误差，提高了轮廓的加工精度，同时，取消了前瞻计算，显著提高了插补运算的效率。

基于自适应响应面法的脂肪组织材料参数反求

基于自适应响应面法的脂肪组织材料参数反求CUI Shihai;DUAN Haitong;LI Haiyan;HE Lijuan;LÜ wenle;RUAN Shijie【摘要】不同文献中的脂肪组织材料参数相差很大,人体有限元模型中脂肪组织的生物仿真度有待提高.本研究构建了脂肪组织压缩试验有限元模型,采用Ogden超弹性材料本构并进行筛选试验设计,确定其各个因子对目标响应的影响程度,选择Ogden系数与剪切松弛模量两项对目标响应影响较大的参数作为反求目标.利用有限元方法与优化策略相结合,基于自适应响应面法对脂肪组织的材料参数进行反求,将反求得到的材料参数应用于仿真中,得到仿真曲线与实验曲线的相关系数为0.98876.研究结果表明,应用基于反求策略得到的材料参数输出的仿真曲线与实验曲线高度吻合,在仿真中采用该反求方法获得的脂肪组织材料参数具有更高的生物仿真度.【期刊名称】《生物医学工程研究》【年(卷),期】2019(038)002【总页数】5页(P156-160)【关键词】脂肪组织;压缩实验;试验设计;材料参数;反求方法【作者】CUI Shihai;DUAN Haitong;LI Haiyan;HE Lijuan;LÜ wenle;RUAN Shijie【作者单位】;;;;;【正文语种】中文【中图分类】R3181 引言在全球肥胖人群不断增长的趋势下[1-2]，肥胖乘员的乘车安全越来越受到关注。

目前肥胖乘员的损伤机理尚不明确，有限元模型[3-5]、尸体样本[6]以及假人模型[7]等是研究乘员损伤机理、评价乘员损伤的常用工具。

其中，有限元模型在肥胖乘员损伤机理研究中有着独到的优势，其可以反映身体各部分力学响应情况，且具有可重复性，同时能将混淆的影响因素单独分开。

对于肥胖有限元模型，其增加的大量脂肪是影响生物力学响应的重要因素，脂肪组织材料本构的选择及参数的确定是影响其生物仿真度及损伤评价的关键因素。

外文翻译切削刀具

英文原文CUTTING TOOLSWhen selecting cutting tools for a job, the first thing to consider is what type of operation needs to be performed. Here is a quick description of the basic cutting tools most often used in milling operations.DRILLA drill is used to create a round, cylindrical hole in a workpiece. Drilled holes can be "through holes" or "blind holes". A "blind hole" is not cut entirely through a workpiece. Quite often, an engineering blueprint will specify a drilled hole to be drilled to "full diameter depth." This means that the hole diameter must be a specified depth without regard to the angled tip of the drill. When you measure your tool length offset, you are measuring the length of the drill and its tip. So how deep do you drill the hole so that the full diameter depth is correct? Well, you need to know how long the drill point is.TIP: The length of the drill point is determined by the tool point angle and the drill diameter. You can calculate the length of the drill point by multiplying the drill diameter by a constant; the value of the constant depends on the drill point angle (most standard high-speed steel drills have a tool point angle of 118 degrees).For a drill point angle of:118 degrees135 degrees141 degreesMultiply the drill diameter by:0.30.2070.177Using these constants allows you to calculate the drill point lengthwithin a few thousandths of an inch.CENTER DRILLA center drill is a small drill with a pilot point. It is used to create a small hole with tapered walls. When a hole's location must be held to a close tolerance, use a center drill first and then use a twist drill to finish the hole. The tapered walls of the center-drilled hole will keep the twist drill straight when it begins to drill into the workpiece.TIP: Many machinists use this rule of thumb: If the tolerance of the diameter of a center-drilled hole is not critical, drill as deep as you want this diameter to be. With a standard, 60-degree center drill below 0.375-inch diameter, the hole diameter produced will be close to the depth you drilled. With larger center drills –0.375 inch and above –the depth-to-diameter ratio becomes larger, so you could be off by as much as 0.080 to 0.100 inch.REAMERA reamer is designed to remove a small amount of material from a drilled hole. The reamer can hold very close tolerance on the diameter of a hole, and give a superior surface finish. The hole must be drilled first, leaving 0.005 to 0.015 inch of stock on the walls of the hole for the reamer to remove.TIP: The ideal situation for hole size accuracy and location when reaming is to process the hole with the following steps: the hole is first drilled, then bored, then reamed.TIP: Stock allowance for a reamed hole will depend on the size of the hole. A general rule is:for holes less than 1/2"for holes greater than 1/2"stock of less than 0.0150" on diameterstock of 0.030" on diameterThe type of workpiece material and the method used to create the hole will affect the stock allowance.TIP: A reamer produces the best, most uniform surface finish when it is fed into and out of the hole using the G85 (bore in, bore out) canned cycle. Many people try to save time by using the G81 (drill) canned cycle, which will feed into a hole and rapid out. It is quicker than G85, but will usually leave a helical swirl mark on the cylindrical surface of the hole. Although this swirl mark is only a cosmetic flaw and doesn't affect the size of the hole, the appearance of the hole may be rejected by some customers.TAPA tap is used to create screw threads inside of a drilled hole.NOTE: Great care must be taken when using a milling machine to perform a tapping operation.TIP: If you are using a machine with rigid tapping, feedrate (in inches per minute) = thread pitch x revolutions per minute. Also, you should never tap more than 1.5 x the tap's major diameter. Threaded connections will not increase in strength if the contact length is more than 1.5 times the diameter of the fastener. If you need threads that are deeper, machine tap them first and hand-tap them to finished depth. If you tap deeper than 1.5 x the hole diameter, your chances of breaking the tap increase dramatically. Chip control becomes a problem. When tapping blind holes, always drill as deep as possible to avoid packing chips below the tap. Using a spiral flute tap will bring the chips up, out of the hole. To further reduce tapping headaches, make sure all holes to be tapped are free of chips, and use a tapping fluid specifically designed for the type of material you are cutting.TIP: Tap drill size is the size of the hole required for a specific tap. For 75% effective threads the formula that will determine the correct drill size is:D – 1/N, whereD = major diameter of the tap andN = number of threads per inchA tapped hole with 75% of thread depth has only 5% less strength than 100% thread and takes only 1/3 of the cutting force of a 100% thread.END MILLAn end mill is shaped similar to a drill, but with a flat bottom. It is used primarily to cut with the side of the tool to contour the shape of a workpiece.TIP: Programming an end mill to cut contour or pocket tool paths using cutter compensation (G41 and G42) allows you much more flexibility in adjusting the size of machined features. Using cutter compensation allows you to adjust the amount of stock removal. As an end mill wears, minor offset adjustments allow you to make every part the same size. You may also use a different size end and have the machine cut the same part features as with the end mill originally programmed for that tool path.BULL END MILLA bull end mill is the same as a regular end mill except that there is a radius on the corner where the flutes meet the bottom of the end mill. This radius can be any size up to one-half of the tool's diameter.TIP: Bull end mills are effective for producing a corner radius between a wall and a floor on a given part feature. They also add to the strength of an end mill. When machining hard, tough to cut materials, the sharp corners on a standard end mill tend to chip and wear faster than an end mill with a corner radius. The radius on a bull end mill provides a more gradual shearing entry in to the work piece.BALL END MILLA ball end mill is a bull end mill where the corner radius is exactly 1/2 the tool's diameter. This gives the tool a spherical shape at the tip. It can be used to cut with side of the tool like an end mill.TIP: The primary purpose of a ball end mill is to machine lofted surfaces. The spherical shape of the tool is able to move along any undulating surface and cut anywhere along the cutter's "ball end." As a ball can roll over a surface, a ball end mill can be used to cut any such surface.INSERT END MILLAn insert end mill is the same as a standard end mill but with replaceable carbide inserts.TIP: Insert end mills are designed to remove metal at higher rates than solid carbide. They come in a large range of diameters and are able to cut at a deeper depth of cut. This is fantastic but, when using these cutters, it is a good idea to calculate the horsepower required to make a cut. Piece of cake on your Haas control: There is a button on the front labeled "HELP/CALC." Press this button once to get the Help menu, press it again to get the Calculator functions. Use the PAGE UP/PAGE DOWN keys to scroll between three pages: Trigonometry Help, Circular Interpolation Help, and Milling Help. Each one of these pages has a simple calculator in the upper left hand corner. On the Milling Help page, you can solve three equations:1. SFM = (cutter diameter [in.]) * RPM * 3.14159 / 122. (Chip load [in.]) = (feed [in. per min.]) / RPM / # of flutes3. (Feed [in. per min.]) = RPM / (thread pitch)With all three equations, you may enter all but one of the values and the control will compute and display the remaining value. To calculate the horsepower required for a cut, you must enter values for RPM, feed rate, number of flutes, depth of cut, width of cut, and choose a material from the menu. If you change any of the above values, the calculator will automatically update the required horsepower for the cut you intend.The next thing to consider when choosing cutting tools for a job is what material you are going to cut. The most common materials cut in the metalworking industry can be divided into two categories: non-ferrous and ferrous. Non-ferrous materials include aluminum and aluminum alloys, copper and copper alloys, magnesium alloys, nickel and nickel alloys, titanium and titanium alloys. Common ferrous materials include carbon steel, alloy steel, stainless steel, tool steel, and ferrous cast metals like iron. Non-ferrous metals are softer and easier to cut, with the exception of nickel and titanium. Ferrous metals, on the other hand, are generally harder in composition and tougher to cut.Cutting tool material is one of the biggest decisions you'll have to makewhen choosing a cutting tool. Most all of the cutters described above are available in three basic materials: high-speed steel, solid carbide, and carbide insert style. Almost all of the basic cutting tool materials can be used to cut almost all materials. It really boils down to performance. High-speed steel cutting tools have very high toughness but lack wear resistance. Carbide, on the other hand, has a very high wear resistance but chips and breaks easily. Carbide will always be able to cut materials at higher speeds and feeds, but is more expensive. Carbide insert cutting tools are very useful in high-production situations because the inserts are designed with multiple cutting edges on each insert. When they become worn out, you index the inserts to the next cutting edge, and when all cutting edges are used, you only replace the inserts and not the whole tool.TIP: If you are using a high-speed steel drill, always use a center drill to get the hole started. Then drill the hole. This will ensure that the drilled hole is in the correct location. If you are using a carbide drill, it is not necessary to center drill first because carbide drills are ground with a self-centering tip. Using a carbide drill to drill a hole that is already center drilled will damage the drill. The outer cutting edges will contact the tapered walls before the tip of the drill begins to cut. This will shock the outer cutting edges and cause the drill to chip. Carbide drills must begin to cut at the tip before the outer cutting edges.Each one of these cutting tool materials is available with a variety of different coatings to enhance their performance. The three coatings most widely use today are titanium nitride (TiN), titanium carbonitride (TiCN), and titanium aluminum nitride (TiAlN). TiN coating is easily recognized by its gold color. The advantages of TiN coating are increased surface hardness, increased tool life, better wear resistance and higher lubricity, which decreases friction and reduces edge build-up. TiN coating is mostly recommended for machining low alloy steel and stainless steel. TiCN coating is gray colored compared to TiN, and even harder. Its advantages are increased cutting speed and feeds (40% to 60% higher compared to TiN), higher metal removal rates, and superior wear resistance. TiCN coatings are recommended for machining all material types. TiAlN coating appears gray or black and is primarily used to coat carbide. It can work atvery high temperatures, up to 800 degrees Celsius, which makes it ideal for high-speed machining without coolant. Pressurized air is recommended to remove chips from the cutting zone. It works well on hardened steels, titanium and nickel alloys, as well as abrasive materials like cast iron and high silicon aluminum.When selecting end mill tools, the number of flutes, or cutting edges, is an important factor. The more flutes an end mill has, the smaller, or shallower, the flutes are. The solid center section of an end mill is approximately 52% of the end mill's diameter on a two-flute end mill. The center section of a three-flute end mill is 56% of its diameter, and an end mill with four or more flutes has a center section that is 61% of its diameter. This means that the more flutes an end mill has, the more rigid it will be in the cut. Two-flute end mills are recommended for soft, gummy materials such as aluminum and copper. Four-flute end mills are recommended for harder, tougher steel materials.中文译文切削刀具在选择切削刀具时，首先应考虑需要执行的操作。

【高中生物】新研究找到调节饱腹感和体重的基因开关

【高中生物】新研究找到调节饱腹感和体重的基因开关
我们到底为什么会变胖？而减肥为什么会这么困难？
最近来自德国的科学家们发现了一个调节体重和摄食的新分子，他们发现组蛋白去乙
酰化酶5（HDAC5）对瘦素（leptin）信号途径具有显著影响，而leptin在调节饱腹感以
及机体应对食物的适应性变化方面具有关键作用。

文章作者这样表示：“HDAC5是脂肪组织与脑部食欲调节区域之间交流的重要联系。

”初步试验已经表明下丘脑部位HDAC5的蛋白合成及活性会受到高脂饮食刺激而出现增加，
高脂饮食会导致脂肪堆积同时调节饱腹感的激素leptin也会增加。

HDAC5就像位于脑部的一个分子开关帮助机体辨别脂肪组织到底已经“塞”得有多满。

如果没有HDAC5，机体就
对无法对进食进行适应性调节也无法控制脂肪堆积。

该信号途径紊乱会导致肥胖发生。

这项研究表明，不能合成HDAC5的小鼠对leptin的应答情况也会显著下降??这种情
况也叫做leptin抵抗。

研究人员发现这种小鼠会持续进食，与对照小鼠相比，缺少HDAC5的小鼠更易发生肥胖。

靶向激活HDAC5则会逆转这种情况，这种方法能够帮助肥胖小鼠减
少脂肪减轻体重。

文章作者指出，重建leptin的敏感性是维持体重下降，拮抗肥胖并发症如2型糖尿
病的重要一步，除了饮食和运动的改变，对leptin信号途径具有调节作用的各个分子或
在将来成为药物靶点，推动减肥事业的进行，而他们发现的HDAC5就是其中的一个重要分子。

但他们仍然表示未来还需要许多研究进一步探讨该分子是否适合成为人类肥胖治疗的
药物靶点。

感谢您的阅读，祝您生活愉快。

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Keywords: Parametric curve; Speed-controlled interpolation; Chord error; NURBS
1. Introduction
In modern CAD/CAM systems, pro®les for parts such as dies, vanes, aircraft models, and car models are usually represented in parametric forms. Since conventional CNC machines only provide linear and circular arc interpolators, the CAD/CAM systems have to segment a curve into a huge number of small linearized segments and send them to CNC systems. Such linearized-segmented contours processed on CNC systems are undesirable in real applications for the following reasons:
Fig. 1. The machining systems with parameters transmission.
process, Houng and Yang [4] and Shpitalni et al. [1] developed ®rst-order approximation interpolation algorithms using Euler and Taylor's expansions, respectively. These ®rst-order approximation interpolation algorithms provide uniform curve speed during the interpolation process. Furthermore, the second-order approximation and speedcontrolled interpolation algorithms proposed by Yang and Kong [5] and Yeh and Hsu [6], respectively, yield more precise results. However, these algorithms do not consider chord error explicitly during the interpolation process.
Abstract
Recently, modern manufacturing systems have been designed which can machine arbitrary parametric curves while greatly reducing data communication between CAD/CAM and CNC systems. However, a constant feedrate and chord accuracy between two interpolated points along parametric curves are generally dif®cult to achieve due to the non-uniform map between curves and parameters. A speed-controlled interpolation algorithm with an adaptive feedrate is proposed in this paper. Since the chord error in interpolation depends on the curve speed and the radius of curvature, the feedrate in the proposed algorithm is automatically adjusted so that a speci®ed limit on the chord error is met. Both simulation and experimental results for non-uniform rational B-spline (NURBS) examples are provided to verify the feasibility and precision of the proposed interpolation algorithm. q 2001 Elsevier Science Ltd. All rights reserved.
² the transmission errors between CAD/CAM and CNC systems, i.e. lost data and noise perturbation, may be unavoidable for huge amounts of data;
² the discontinuity of segmentation deteriorates surface accuracy; and
Computer-Aided Design 34 (2002) 229±237
COMPUTER-AIDED DESIGN
/locate/cad
Adaptive-feedrate interpolation for parametric curves with a con®ned chord error
In this paper, we propose an interpolation algorithm that con®nes the chord error within a speci®ed tolerance range during the interpolation process. Since the chord error is closely related to the curve speed and the radius of curvature, the relations among chord error, curve speed, and radius of curvature are identi®ed in the algorithm. The circular approximation is adopted for general parametric curves in the proposed method. Then, the adaptive curve speed based on the chord error of the approximated circular curve is derived and applied to the speed-controlled parameter iteration algorithm to make the chord error within the speci®ed tolerance. To demonstrate the performance of the proposed chord error-controlled interpolator, a NURBS parametric curve example using a personal computer is also provided in this paper.
0010-4485/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved. PII: S 0010-448 5(01)00082-3
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S.-S. Yeh, P.-L. Hsu / Computer-Aided Design 34 (2002) 229±237
There are many different formats for parametric curve representation, such as Bezier, B-spline, cubic spline, and NURBS (non-uniform rational B-spline). The general parameter iteration method used is ui11 ui 1 D ui where ui is the present parameter, ui11 is the next parameter, and D ui is the incremental value. The interpolated points are calculated by substituting ui into the corresponding mathematical model to recover the originally designed curves. Since the cutter moves in a straight path between contiguous interpolated points, two position errors may occur during parametric curve motion: (a) radial error; and (b) chord error [3] as shown in Fig. 2. The radial error is the perpendicular distance between the interpolated points and the parametric curve, and the chord error is the max>imum distance between the secant CD and the secant arc AB . Basically, the radial error is caused by the rounding error of computer systems. With the rapid development of microprocessors for high precision applications, the radial error is no longer a major concern. The chord error is thus the main concern of this paper and we will propose an interpolation algorithm that limits the chord error to a speci®ed tolerance.