Spin-dependent transport induced by magnetization in zigzag graphene nanoribbons coupled to one-dimensional leads

We study spin transport in a zigzag graphene nanoribbon sample with two ferromagnetic strips deposited on the two sides of the ribbon. A tight-binding Hamiltonian was adopted to describe the sample connected to two one-dimensional leads. Our theoretical study shows that the resonance peaks of conductance for the spin-up and spin-down electrons are separated for the parallel configuration of the ferromagnetic strips, while they are not separated for the case of antiparallel configuration. This means that giant magnetoresistance can be produced at particular energies by altering the configurations of the ferromagnetic strips, and the device can be designed as a spin filter.     

带临界锥Sobolev指数项方程组的最小正能量解（英文）

借助Nehari流形,本文证明了一类带临界增长项的非线性系统存在最小正能量解,其中有一组解部分径向对称.推广了在经典Sobolev空间中的结果.     

复杂传播路径条件下激光光强起伏特性研究

对复杂地形情况下实际湍流大气中的激光强度起伏进行了系统的实验观测,分析了光强起伏统计特征的周日及全年变化规律。结果发现：复杂地形情况下实际湍流大气中的激光光强起伏,不论是概率密度分布还是其功率谱等统计特征均与理论上的偏离很大。     

激光大气闪烁的小波频谱分析

激光对数光强起伏的快速傅里叶变换功率谱的无标度区间的标度指数在许多情况下很不稳定,并且超出了理论界限,因而本文引入了离散小波变换（ＤＷＴ）频谱分析。通过对１／ｆ信号的快速傅里叶变换频谱和离散小波换频谱的对比分析,验证了离散小波变换频谱分析的优越性。激光大气闪烁的离散小波变换频谱的无标度区间的标度指数在一天内（除日出后和日落前两段时间外）的变化比较稳定,并且超出理论界限。这此结果表明,对于一般在大气     

RESEARCH ANNOUNCEMENTSA Cone Pseudo-differential Calculus

Thecalculusofpseudthdifferentialoperatorsonsingularspacesandtheconceptofellipti-cityinoperatoralgebrasonmanifoldswithsingularitieshavebecomeanenormouschallengeforanalysists.Theso-calledconealgebras(withdiscreteandcontinuousasymptotics)areinvesti-gatedbymanymathematicians,especiallybyB.W.Schulze,whodevel0pedandenrichedconeandedgepseudo-differentialcalculus,seeSchulzel4-7]lRempelandSchulzeI2'3].Inthisnote,weconstructaconepseudo-differentialcalculusfor0peratorswhichrespectc0normalasymptoticsofa…     

激光大气闪烁饱和的孔径平均效应

理论分析了湍流介质中一定孔径内光强起伏（闪烁）的频谱特征，在6.8km的大气传播距离上同时测量了激光在针孔和φ260mm孔径内的闪烁，根据两者功率谱特征的对比分析结果以及两者闪烁均方差间的关系，指出孔径平均效应可以在一定程度上消除激光大气闪烁的饱和效应，从而可以利用孔径平均效应在临界强起伏条件下测量湍流强度。     

利用湍流廓线获得斜程大气相干长度的实验研究

 用两种方法获得有限高度斜程大气相干长度。一种方法用安置在测量铁塔上的温度脉动仪以及多普勒声雷达测量了大气边界层下部折射率结构常数廓线，用以计算有限高度球面波斜程大气相干长度；另一种方法用系留气球搭载一个点光源，在地面用差分光学系统接收球面波到达角起伏法测量了实时斜程大气相干长度。对实验结果进行了比较和分析，二者都反映了实际大气斜程相干长度的时间变化特点。两种方法结果的相关性比较好，因此两种方法都可以在大气光学传输研究中应用。最后在实验的基础上对湍流廓线计算球面波斜程大气相干长度作了讨论。     

MULTIPLE POSITIVE SOLUTIONS FOR A CLASS OF QUASI-LINEAR ELLIPTIC EQUATIONS INVOLVING CRITICAL SOBOLEV EXPONENT

In this paper, we study the multiplicity results of positive solutions for a class of quasi-linear elliptic equations involving critical Sobolev exponent. With the help of Nehari manifold and a mini-max principle, we prove that problem admits at least two or three positive solutions under different conditions.     

EXISTENCE RESULTS FOR DEGENERATE ELLIPTIC EQUATIONS WITH CRITICAL CONE SOBOLEV EXPONENTS

In this paper, we study the existence result for degenerate elliptic equations with singular potential and critical cone sobolev exponents on singular manifolds. With the help of the variational method and the theory of genus, we obtain several results under different conditions.     

凹凸性混合的非线性Schroedinger方程解的存在性定理

讨论非线性Ｓｃｈｒｏｅｄｉｎｇｅｒ方程－Δｘ＋ｑ（ｘ）ｕ＋λｕ＋Ｐ（ｘ）│ｕ│＾ｐ＝１ｕ＋Ｑ（ｘ）│ｕ│＾α－１ｕ ｘ∈Ｒ＾Ｎ的多解存在性，其中ｑ（ｘ）满足周期性，Ｐ（ｘ），Ｑ（ｘ）是满足一定条件的连续函数，λ∈Ｒ落在－Δ＋ｑ的谱隙中，０〈α〈Ｎ－２／Ｎ＋２〈１〈ｐ〈Ｎ＋２／Ｎ－２。