Ni81Fe19/Al2O3/NixFe1-x结的隧道平面Hall效应

Ni₈₁Fe₁₉/Al₂O₃/Ni_xFe_100-x三层结的隧道平面Hall(TPH)效应与单层膜和二层结的一般平面Hall效应不同 .这效应涉及自旋极化传输 ,故TPH电压与两铁磁层内磁矩的夹角相关 .并报道了铁磁层的成分、磁特性以及绝缘势垒层的厚度等对TPH效应的影响 .     

关于m-HPK(n1,n2,n3,n4)-残差图

本文研究了3-维超平面完备残差图以及m 重3-维超平面完备残差图. 利用容斥原理以及集合的运算性质等方法, 分别获得了3-维超平面完备残差图和m 重3-维超平面完备残差图的最下阶以及二者的唯一极图, 将文献[1] 中定义的残差图从平面推广到超平面上.     

The generalized bisymmetric solutions of the matrix equation A 1 X 1 B 1 + A 2 X 2 B 2 + ? + A l X l B l = C and its optimal approximation

For fixed generalized reflection matrix P, i.e. P ^T  = P, P ² = I, then matrix X is said to be generalized bisymmetric, if X = X ^T  = PXP. In this paper, an iterative method is constructed to find the generalized bisymmetric solutions of the matrix equation A ₁ X ₁ B ₁ + A ₂ X ₂ B ₂ + ⋯ + A _l X _l B _l  = C where [X ₁,X ₂, ⋯ ,X _l ] is real matrices group. By this iterative method, the solvability of the matrix equation can be judged automatically. When the matrix equation is consistent, for any initial generalized bisymmetric matrix group , a generalized bisymmetric solution group can be obtained within finite iteration steps in the absence of roundoff errors, and the least norm generalized bisymmetric solution group can be obtained by choosing a special kind of initial generalized bisymmetric matrix group. In addition, the optimal approximation generalized bisymmetric solution group to a given generalized bisymmetric matrix group in Frobenius norm can be obtained by finding the least norm generalized bisymmetric solution group of the new matrix equation , where . Given numerical examples show that the algorithm is efficient. Research supported by: (1) the National Natural Science Foundation of China (10571047) and (10771058), (2) Natural Science Foundation of Hunan Province (06JJ2053), (3) Scientific Research Fund of Hunan Provincial Education Department(06A017).     

(YBa2Cu3O7)24/(PrBa2Cu3O7)2多层膜的超导转变展宽和维度 *

测量了(YBa₂Cu₃O₇)₂₄/(PrBa₂Cu₃O₇)₂ 多层膜在强磁场下的超导转变展宽 .这种YBa₂Cu₃O₇层间具有耦合 退耦合的临界绝缘层PrBa₂Cu₃O₇厚度以及由 3D向 2D过渡的YBa₂Cu₃O₇层厚度的多层膜 ,其不可逆场遵守H ∝ ( 1-t)μ关系 ,其 μ值约为1 ,介于3D( μ =3/2 )和2D( μ =1 /2 )之间 .磁通运动的热激活能的结果表明 ,对于H∥c和H⊥J的磁场位形 ,遵守U∝lnH关系 ,即磁通涡旋处于2D区 .而对于H∥ab和H⊥J ,H∥ab和H∥J两种磁场位形 ,激活能U随磁场的增加而线性减小 ,表明磁通涡旋处于3D态 .讨论了上述维度变化的可能物理机制 .     

Stochastic H2 / H∞ Control for Poisson Jump-Diffusion Systems

This paper is concerned with stochastic H_2/H_∞ control problem for Poisson jump-diffusion systems with(x, u, v)-dependent noise, which are driven by Brownian motion and Poisson random jumps. A stochastic bounded real lemma(SBRL for short) for Poisson jump-diffusion systems is firstly established, which stands out on its own as a very interesting theoretical problem. Further, sufficient and necessary conditions for the existence of a state feedback H_2/H_∞ control are given based on four coupled matrix Riccati equations. Finally, a discrete approximation algorithm and an example are presented.     

环F2+uF2+vF2上线性码广义Gray像

本文定义了环F2+uF2+vF2到域F2的广义Gray映射φ像,研究了环F2+uF2+vF2上线性码的广义Gray像.利用广义Gray映射φ的线性性,证明了环F2+uF2+vF2上线性码C的广义Gray像φ(C)满足dH(C)=dH(φ(C))且φ(C⊥)φ(C)⊥.同时,给出了F2+uF2+vF2上循环码C的广义Gray像φ(C)为F2上的4-拟循环码.     

Performance of the（BMAP1, BMAP2 ）/（PH1, PH2 ）/N Retrial Queueing System with Finite Buffer

This paper consider the （BMAP1, BMAP2）/（PH1, PH2）/N retrial queue with finite-position buffer. The behavior of the system is described in terms of continuous time multi-dimensional Markov chain. Arriving type I calls find all servers busy and join the buffer, if the positions of the buffer are insufficient, they can go to orbit. Arriving type II calls find all servers busy and join the orbit directly. Each server can provide two types heterogeneous services with Phase-type （PH） time distribution to every arriving call （including types I and II calls）, arriving calls have an option to choose either type of services. The model is quite general enough to cover most of the systems in communication networks. We derive the ergodicity condition, the stationary distribution and the main performance characteristics of the system. The effects of various parameters on the system performance measures are illustrated numerically.     

高TcYBa2Cu3O7/PrBa2Cu3O7超晶格的微结构分析

利用高分辨透射电子显微镜对高T_c YBa₂Cu₃O₇/PrBa₂Cu₃O₇(以下简称为YBCO/PrBCO)超晶格的微结构进行了系统的观察分析,高分辨电子显微象(HREM)表明YBCO/PrBCO超晶格层与层之间具有清晰的衬度,没有界面互扩散,通过HREM象观察,发现衬底表面的原子台阶和缺陷使薄膜最初1—2个晶胞层中出现层错等缺陷,但这些缺陷并没有向薄膜内部扩展,当薄膜厚度超过几个晶胞层后,其结构趋于完整。另外,在HREM照片上还可看出YBCO/PrBCO超晶格的调制周期存在波动,波动范围相当于一个晶胞层厚度,实验结果表明,利用YBCO/PrBCO超晶格研究CuO₂面的二维超导电性时,临界温度T_c和临界电流密度J_c的变化不仅与二维CuO₂面的失耦程度有关,还会受到各种晶格缺陷的影响,对YBCO/PrBCO超晶格和超薄YBCO膜的输运特性进行理论解释时,必须考虑衬底和晶格缺陷造成的影响。     

Uniqueness of the Unconditional Basis of ?1 (?p) and ?p (?1), 0 < p < 1

We prove that the quasi-Banach spaces ₁ (_p) and _p (₁), 0 < p < 1 have a unique unconditional basis up to permutation     

环F2+uF2+vF2上自对偶码的两种构造方法

本文研究环R=F2+uF2+vF2上的自对偶码问题.利用Rn到F3n2的Gray映射及R上的自对偶码C的Gray像为F2上自对偶码,获得了R上任何偶长度的自对偶码存在性的结论.最后,给出了R上两种构造自对偶码的方法.     

C60和C70薄膜光吸收谱研究 *

用透射光谱法和光热偏转谱法测得了C₆₀和C₇₀薄膜在宽能量范围(0.6到6.5 eV)的光谱,并计算了吸收系数.根据分子轨道模型分析了C₆₀和C₇₀薄膜的光跃迁行为.Fuller烯薄膜的弱吸收光谱与非晶硅的类似.用Tauc公式确定了C₆₀和C₇₀薄膜的光学带隙分别为1.75和1.65eV.Urbach吸收边和亚隙吸收表明Fuller烯薄膜中存在无序状态,导致带尾态和缺陷态,这虽非C₆₀或C₇₀薄膜所固有,但无序的存在给准确测定Fuller烯薄膜的禁带宽度带来障碍.讨论了偏转介质与衬底对Fuller烯薄膜的弱吸收光谱的影响.     

论模糊差分方程xn+1=a+bxn/A+xn-1

讨论非线性模糊差分方程x_n+1=a+bx_n/A+x_n-1（n=0,1,…）正解的存在性、有界性及正解的渐近表现。其中是正模糊数数列、及初始值是正模糊数。     

λKv的最大K2,3填充设计和最小K2,3覆盖设计

对于一个有限简单图G,λK_v的G-设计(G-填充,G-覆盖),记为(v,G,λ)-GD((v,G,λ)-PD,(v,G,λ)-CD),是一个(X,B),其中X是K_v的顶点集,B是K_v的子图族,每个子图(称为区组)均同构于G,且K_v中任一边都恰好(最多,至少)出现在B的λ个区组中.一个填充(覆盖)设计称为是最大(最小)的,如果没有其它的这种填充(覆盖)设计具有更多(更少)的区组.本文对于λ>1确定了(v,K_2,3,λ)-GD的存在谱,并对任意λ构造了λK_v的最大K_2,3-填充设计和最小K_2,3-覆盖设计.     

2(n1+n2)-(k1+k2)42混合水平裂区设计包含纯净效应的条件

混水平部分因析裂区设计在各类试验中有广泛应用. 在三因子及更高阶交互作用可以忽略这一很弱的假设下, 试验者可以得到纯净主效应或者纯净两因子交互作用成分的无偏估计. 本文给出了含有两个四水平因子和若干二水平因子的混水平裂区设计包含各类纯净主效应或者纯净两因子交互作用成分的条件以及构造相应设计的方法.     

球面稳定同伦群的两个新元素h0(b1)3(γ)s和(b1)3g0(γ)s

本文证明了当p(＞-)11,3(<-)s＜p-3时,h0(b1)3∈Ext7,3p2q+qA(H*V(2),Zp),(b1)3g0∈Ext8,3p2q+pq+2q(H*V(2),Zp)在Adams谱序列中分别收敛到π*V(2)的非零元,h0(b1)3(γ)s∈Ext7+s,(s+3)p2q+(s-1)pq+(s-3)A(Zp,Zp)在Adams谱序列中分别收敛到π*S的非零p阶元.     

BaTiO3/SrTiO3超晶格的二次谐波产生研究

用激光分子束外延技术生长了BaTiO3 /SrTiO3 超晶格并首次对之采用二次谐波产生的方法进行了研究 .实验表明其结构为类似BaTiO3 的四方相结构 .实验得到的材料的有效倍频系数远大于BaTiO3 薄膜 ,也大于BaTiO3 体材料的值 .这表明这种人为控制的BaTiO3 /SrTiO3 超晶格结构具有较大的非线性光学的应用前景 .     

BaO-Y2O3(La2O3)-CuO三元系相图的研究

本文采用X射线衍射,热学分析、超导电性测量等方法测定了La₂O₃-CuO,BaO-CuO,Y₂O₃-CuO二元系相图,BaO-La₂O₃-CuO,BaO-Y₂O₃-CuO三元系室温截面。在这两个三元系的富CuO区,存在Ba_xLa_2-x CuO₄(x≤0.07),BaLaCu₂O_5+δ,BaLa₄Cu₅O_14+δ,BaLa₂Cu₂O₆和Ba₂YCu₃O_9-y,BaY₂CuO₉化合物。Ba_xLa_2-x,CuO₄(x≤0.07),BaLa₄Cu₅O_14+δ,BaLaCu₂O_5+δ,BaLa₂Cu₂O₆均属四方晶系,点阵常数分别为a=5.356,c=13.20;a=8.660,c=3.863;a=3.917,c=11.75;a=3.992,c=19.96.Ba₂YCu₃O_9-y属正交畸变钙钛矿结构,a=3.892,b=3.824,c=11.64,空间群为Pmmm。BaY₂CuO₅具有正交结构,a=7.123,b=12.163,c=5.649;空间群为Pbnm。研究了组成与超导电性的关系,考查了烧结温度对Ba₂YCu₃O_9-y化合物结构和超导电性的影响,并对超导电性产生的原因进行了讨论。