模n剩余类环零因子图的一些性质

模n剩余类环Z_n的零因子图记为Γ(Z_n),其顶点为Z_n的所有非零零因子,两个不同的顶点x与y有一条边相连当且仅当xy=0.对Γ(Zn)和(?)的欧拉性及一笔画性进行了探讨,完全确定了当n为何值时,Γ(Z_n)和(?)为欧拉图或是一笔画图.     

Theoretical analyses on improved beam properties of GaSb-based 2.X-μm quantum-well diode lasers with no degradation in laser parameters

An asymmetric laser heterostructure is developed to improve the beam properties of GaSb-based diode lasers with no degradation in laser parameters.Employing the semivectorial finite difference method,the dependences of beam divergence and optical confinement factor on waveguide width and refractive index step are investigated theoretically.After carefully design,a particular asymmetric laser structure is proposed.Its beam divergence in the fast axis is reduced from 61° to 34° compared with that of the broad-waveguide structure.The optical confinement factor is approximately equal to 0.0362 and comparable to that of the conventional broad-waveguide structure.     

Canard轨迹原理

为了精确的求出Canard轨迹的描述方程,提出了一个分段表达的非线性模型,能直接求出一个非线性二阶自治方程的相轨迹方程的解析解,能定量求出Canard轨迹的描述方程和参数条件,可以用两类方程简单描述所有的Canard轨迹. 关键词： 非线性系统 Canard轨迹 弛张振荡     

一个组合预测模型及应用

根据时间序列分析法和 Markov链分析法 ,建立同周序列 -Markov链组合预测模型 ,采用深圳成份指数进行实证分析 ,得到了 2 0 0 3年深圳成份指数的运行趋势     

Effective absorption enhancement in small molecule organic solar cells using trapezoid gratings

We demonstrate that the optical absorption is enhanced in small molecule organic solar cells by using a trapezoid grating structure. The enhanced absorption is mainly attributed to both waveguide modes and surface plasmon modes, which is simulated by using finite-difference time-domain method. The simulated results show that the surface plasmon along the semitransparent metallic Ag anode is excited by introducing the periodical trapezoid gratings, which induce the increase of high intensity field in the donor layer. Meanwhile, the waveguide modes result in a high intensity field in acceptor layer. The increase of field improves the absorption of organic solar cells significantly, which is demonstrated by simulating the electrical properties. The simulated results also show that the short-circuit current is increased by 31% in an optimized device, which is supported by the experimental measurement. Experimental result shows that the power conversion efficiency of the grating sample is increased by 7.7%.     

关于色散方程u_t=au_(xxx)一类显式差分格式的讨论

关于色散方程u_t=au_(xxx)差分格式的讨论,在[1]和[2]中,分别提出了中层为五点和六点的显式差分格式,其稳定区域分别为 0≤r≤0.7016和-0.0625 ≤r≤1.1851.本文针对这一问题,讨论中层为七点的一类差分格式的稳定性.[1]中格式是本文的特例,并且这类格式的最佳稳定区域为0≤r≤2.394,大约是[2]中稳定范围的二倍,[1]中稳定范围的三倍.     

高校科技资源配置效率比较分析

基于数据包络分析(DEA)模型,为讨论高校在不同方面的表现,定义了不同投入产出的四种模型,结果表明不同的投入产出组合会得到不同的效率得分,此外通过不同模型的比较,可以知道十年间新疆高校科研效率的对比情况.为进一步分析新疆高校的科研效率情况,对新疆9所高校的科研效率做了进一步分析,通过对这九所高校的技术及规模效率分析,对高校的进一步发展提出了建议.     

单结管二阶电路中的周期迭加现象

本文介绍了发生在单结管二阶电路中的周期迭加现象,并在相平面图和频谱图上观察了周期迭加现象的产生过程。 关键词：     

磷酸氯化铵凝结净化-气相色谱法测定烟草中9种农药残留

建立了烟草中两大类9种农药残留气相色谱分析方法。烟叶样品用丙酮提取,经H3PO4-NH4Cl溶液凝结过滤,硅胶柱层析净化,GC-ECD检测。9种农药的平均回收率为83.1%～100.1%,相对标准偏差为4.9%～10%,加标最低检出量为0.01mg/kg,方法的准确度和精密度均符合农药残留测定的技术要求。磷酸氯化铵凝结法适用于本底基质较为复杂的烟草样品的净化,可满足烟叶中多种抑芽剂和拟除虫菊酯类农药残留同时检测的实际需要。     

High power 2-μm room-temperature continuous-wave operation of GaSb-based strained quantum-well lasers

A high power GaSb-based laser diode with lasing wavelength at 2 μm was fabricated and optimized. With the optimized epitaxial laser structure, the internal loss and the threshold current density decreased and the internal quantum efficiency increased. For uncoated broad-area lasers, the threshold current density was as low as 144 A/cm2 (72 A/cm2 per quantum well), and the slope efficiency was 0.2 W/A. The internal loss was 11 cm-1 and the internal quantum efficiency was 27.1%. The maximum output power of 357 mW under continuous-wave operation at room temperature was achieved. The electrical and optical properties of the laser diode were improved.