具有若干个光谱带宽的光谱仪

本发明提供一种光谱仪，它有两个平行的测量光路（2a或2b），每个测量光路中有一个光学输入（3a或3b）和一个光学输出（4a或4b）。每个测量光路在输入侧都有一根耦合纤维（5a或5b），在输出侧都有一根去耦合纤维（10a或10b）。     

1987年华东师范大学硕士学位研究生入学试题及题解

试题名称:数字电路和微机原理一、图1(a)、图2(a)、图3(a)所示电路的对应输入波形分别如图1(b)、图2(b)、图3(b)所示,画出其相应的输出波形. (15分)     

非对称多模量子叠加态光场的等幂高次和压缩

根据量子力学中的态叠加原理,构造了由多模复共轭相干态|{zj(a)*}>q和多模复共轭相干态|{zj(b)*}>q的相反态|{-zj(b)*}>q的线性叠加所组成的非对称两态叠加多模量子叠加态光场|ψ(2)>q,利用多模压缩态理论研究了态|ψ1f(2)>q的等幂高次和压缩特性,结果表明: 1)当Rj(a)=Rj(b)和ψj(a)-ψj(b)=±(2k 1)π(k=0,1,2,3……),态|ψ1f(2)>q的两个正交相位分量均处于N-H最小测不准态的结果;2)当Rj(a)=Rj(b)=Rj和ψj(a)=ψj(b)=ψj,ψ态|1f(2)>q的等幂高次和压缩与文献3的结果相似; 3)当Rj(a)≠Rj(b)=Rj和ψj(a)=ψj(b)=ψj,且和满足一定条件时,无论qN为奇数还是偶数,态|ψ1f(2)>q的两个正交相位分量均可分别呈现周期性变化的等幂高次和压缩效应,但qN为奇数时的压缩深度大于qN为偶数时的压缩深度。     

Sr2CuO3+x无公度调制结构的高分辨电子显微学研究

锶铜氧超导化合物Sr2CuO3+x有无公度调制结构,Zhang H等人把它当作52a×52a的超结构,对高分辨电子显微像作了平均处理,建立了公度调制近似下的结构模型。本文用高分辨电子显微像解卷处理方法研究了Sr2CuO3+x的无公度调制结构。图1a、b分别为Sr2CuO3+x[001]和[010]电子衍射花样,强衍射斑为主衍射,每个主衍射的周围有卫星衍射,呈二维分布,反映出二维无公度调制结构。根据主衍射测得基本结构属四方晶系,空间群I/4mmm,晶胞参数a0=3·79和c0=12·45。两个调制波矢分别为q1≈0·1966a*+0·1924b*,q2≈-0·1962a*+0·1898b*,调制波矢的方向略…     

C取向GdBa2Cu3O7—X膜中a,b取向小颗粒钉扎的TEM研究

C取向YBa_2Cu_3O_(7-x)超导薄膜中已获得了高临界电流密度Jc=10~6A/cm~2。随着薄膜的应用,磁通钉扎的机理越来越为人们所重视。外加磁场在平行于YBa_2Cu_3O_(7-x)的a—b平面时,a—b面会产生本征钉扎,形成高密度的临界电流密度,但垂直于基片方向的高密度电流在应用中也是需要的。     

新品发布

Intel工业级嵌入式Wi-Fi模块研华研华公司最近在工业和企业嵌入式市场中又推出了4款具有7年长供货期的Intel工业级嵌入式无线模块。研华是唯一与Intel合作提供一站式平台集成服务的工控机供应商。EWM-W137H是一种双频IEEE802.11a/b/g/n2T2RWi-Fi模块,支持–40～85oC宽温操作,于户内外恶劣环境下,也能具有高性能及高可靠性,例如在军事和车载应用。EWM-W146H是一种双频IEEE802.11a/b/g/n3T3RWi-Fi模块,能稳定提供Wi-Fi无线传输速度,最高可达450Mbps。EWM-W138H是一种双频IEEE802.11a/b/g/n2T2RWi-Fi模块,能     

钪酸盐阴极发射物质相的研究

用多晶X射线衍射方法,研究钪酸盐阴极发射材料在烧结过程中物理化学变化。由BaO-CaO-Al2O3-Sc2O3组成的发射材料中,在10001300℃内,是Ba-Al-O和Ba-Sc-O体系与CaO的混合物;在13001500℃内,是Ba-Al-O和Ba-Sc-O体系互溶生成热力学上的亚稳定态的Ba-Al-Sc-O固溶体。先形成组成约为5BaO-Al2O3-Sc2O3物相,属正交晶系,a=9.725(2),b=8.698(3),c=6.152(3);最后生成组成约为4BaO-Al2O3-0.5Sc2O3物相,属四方晶系,a=14.4996(19),b=4.4996(19),c=5.0265(8).CaO呈游离状态。     

WLAN与EPC网络融合技术研究

首先介绍了EPC网络中,WLAN作为非3GPP接入方式可以采用的3种方案(S2a、S2b、S2c)的实现方式,其次分析比较了3种方案的不同点,最后针对3种方案的特点,结合国内运营商WLAN网络的特点,提出了部署建议.     

基于“北斗”三号PPP-B2b的定位与时间传递

随着“北斗”三号的建成以及通过GEO卫星进行播发的PPP-B2b信号的公布，“北斗”卫星的定位与定时精度再一次得到提升。为了研究PPP-B2b的定位精度以及时间传递性能，开展了对“北斗”三号的PPP-B2b相关实验。首先选取亚太地区的6个测站静态与动态精密单点定位E(East)、N(North)、U(Up)方向上的误差分析，然后又选取了NTSC与USUD测站进行时间传递稳定度分析。定位结果表明，B1I/B3I组合与B1C/B2a组合的PPP-B2b静态定位E方向、N方向、U方向RMS值分别在4.58 cm, 5.34 cm, 2.2 cm与4.18 cm, 4.97 cm, 2.22 cm, B1I/B3I组合与B1C/B2a组合的PPP-B2b动态定位E方向、N方向、U方向RMS值分别在17.99 cm, 19.41 cm, 12.72 cm与22.47 cm, 21.61 cm, 15.11 cm,两种组合表现出定位精度的一致性。PPP-B2b零基线共钟的时间传递普遍在1 ns内波动，时间传递的STD为0.203,10⁵ s的稳定度达到了5.336×10     

BaLaGdTi_3O_(10)晶体的透射电子显微镜研究

BaLaGdTi_3O_(10)晶体是为研制微型激光器件生长的新晶体,其结构未知。由于晶体缺陷太多,用x射线衍射未能确定它的结构。我们用透射电子显微镜Philips EM420和JEM—200CX对BaLaGdTi_3O_(10)晶体进行了研究。从电子衍射花样和晶格象(图1,图2)测得该晶体有正交晶胞,其参数为:a=7.72A b=56.4A c=7.62A晶胞参数c与BaNd_2Ti_3O_(10)晶体的相近,a与b约为BaNd_2Ti_3O_(10)的两倍。晶体极易沿(010)晶面解理。     

Optimization of optical cross-connects with wave-mixing conversion

This paper presents new constructions of multistage wave-mixing networks with arbitrary b/spl times/b space-switching elements, where b /spl ges/ 2. In these networks, for a size of F fiber links and W wavelengths per link, converter requirements are O(Flog/sub b/W) or O(FW/b) for rearrangeable nodes, and O(Flog/sub b/Wlog/sub b/(FW)) or O(FWlog/sub b/(FW)/b) for different types of strictly nonblocking nodes inspired from the Cantor topology. In all cases, the worst case number of cascaded conversion is O(log/sub b/W). When b=W /spl les/ F, the required number of converters, and the worst case number of cascaded conversions are respectively O(F) and O(1), and are both optimal up to a constant. The new networks generalize and improve upon previous wave-mixing networks based on 2/spl times/2 space switches.     

Stability Criteria With Less LMI Variables for Neural Networks With Time-Varying Delay

In this letter, simplified delay-dependent stability criteria for neural networks are derived by using a simple integral inequality. The results are in terms of linear matrix inequalities (LMIs) and turn out to be equivalent to some existing results but include less number of LMI variables. This implies that some redundant variables in the existing stability criteria can be removed while maintaining the efficiency of the stability conditions. With the present stability conditions, the computational burden is largely reduced. Numerical examples are given to verify the effectiveness of the proposed criteria.      

Global asymptotic stability of a class of feedback neural networks with an application to optimization problems

By applying results from homotopy theory, new conditions are obtained for the existence and uniqueness of an equilibrium for a class of continuous-time feedback neural networks which contains the Hopfield model as a special case. Next, new criteria are established for the global asymptotic stability of the unique equilibrium of this class of neural networks by utilizing Lur'e-type Lyapunov functions and the stability theory for systems of differential inequalities. Several practical stability testing conditions are given. As a special case, criteria are derived for the global asymptotic stability of Hopfield neural networks. This is followed by a robustness analysis of the class of neural networks considered. The results obtained are then applied to an optimization problem.This work was supported in part by the National Science Foundation under Grant ECS 93-19352.     

一种节省能量的移动Ad Hoc网络组播选路协议

鉴于现有基于网孔的移动Ad Hoc网络组播选路协议都滑考虑如何有效使用电池能量的问题，本文提出了一种节省能量组播选路协议（E^2MRP),E^2MRP协议的两个主要特征是：（1）在创建和维护中继组（RG）的过程中交替采用分组平均能量消耗最少和最大节点花费最小两种标准，（2）采用基于图的组播结构，本文通过仿真分析大大降低了节点的能量消耗，特别是在节移动性较低，组播成员较少时更是如此。     

Delay-Dependent Exponential Stability of Neural Networks With Variable Delay: An LMI Approach

This brief focuses on the problem of delay-dependent stability analysis of neural networks with variable delay. Two types of variable delay are considered: one is differentiable and has bounded derivative; the other one is continuous and may vary very fast. By introducing a new type of Lyapunov–Krasovskii functional, new delay-dependent sufficient conditions for exponential stability of delayed neural networks are derived in terms of linear matrix inequalities. We also obtain delay-independent stability criteria. Two examples are presented which show our results are less conservative than the existing stability criteria.     

高阶Hopfield型神经网络的定性分析

本文讨论高阶连续型Hopfield神经网络平衡态的性质,包括平衡态的存在唯一性和稳定性.借助于Banach不动点原理和Lyapunov方法得到了若干平稳态存在唯一和全局渐近稳定的充分条件.作为特例,获得了一阶连续型Hopfield神经网络稳定性的新判据.     

On Global Asymptotic Stability of Cohen–Grossberg Neural Networks With Variable Delays

This paper studies the problems of existence, uniqueness, global asymptotic stability and global exponential stability of the equilibrium of Cohen-Grossberg neural networks with variable delays. An estimation technique based on delay differential inequality with variable coefficients is developed to establish delay-independent/delay-dependent sufficient conditions for global asymptotic/exponential stability. The stability criteria obtained are based on the $M$-matrix theory. These criteria can be easily checked in practice and do not require that the delays be constant or differentiable. In particular, our delay-independent asymptotic/exponential stability criteria remove a restriction on the amplification functions imposed by the existing results. Furthermore, our delay-dependent exponential stability criteria give explicitly the allowable upper bound on the diagonal delays such that the global stability property of Cohen-Grossberg neural networks can be retained. Thus, our new results are of great importance in design and application of Cohen-Grossberg neural networks with variable delays. The effectiveness of the new results is further illustrated by two numerical examples in comparison with the existing results.      

NLq theory: checking and imposing stability of recurrentneural networks for nonlinear modeling

It is known that many discrete-time recurrent neural networks, such as e.g., neural state space models, multilayer Hopfield networks, and locally recurrent globally feedforward neural networks, can be represented as NL_q systems. Sufficient conditions for global asymptotic stability and input/output stability of NL_q systems are available, including three types of criteria: (1) diagonal scaling; (2) criteria depending on diagonal dominance; (3) condition number factors of certain matrices. The paper discusses how Narendra's (1990, 1991) dynamic backpropagation procedure, which is used for identifying recurrent neural networks from I/O measurements, can be modified with an NL_q stability constraint in order to ensure globally asymptotically stable identified models. An example illustrates how system identification of an internally stable model corrupted by process noise may lead to unwanted limit cycle behavior and how this problem can be avoided by adding the stability constraint     

Delay-Dependent Globally Exponential Stability Criteria for Static Neural Networks: An LMI Approach

The problem of globally exponential stability of static neural networks is investigated. Based on the Lyapunov-Krasovskii functional approach, the free-weighting matrix method, and the Jensen integral inequality, new delay-dependent stability criteria of the unique equilibrium of static neural networks with time-varying delays are presented in terms of linear matrix inequalities (LMIs). The stability criteria can easily be checked by using recently developed algorithms in solving LMIs. A numerical example is given to illustrate the effectiveness and less conservativeness of our proposed method.     

一种P2P网络信任模型METrust

 Peer-to-Peer(P2P)网络的异构性、匿名性、自治性等特点导致了一些安全问题,比如伪造、诋毁、协同作弊等,影响了服务质量.提出了一种基于推荐的P2P网络信任模型METrust,节点在网络中拥有唯一的推荐可信度,引入了更新幅度和更新力度两个参数来更新推荐可信度.给出了节点推荐可信度的更新算法;节点根据评价标准的相似程度选择推荐,其中节点的评价标准通过AHP(Analytic Hierarchy Process)方法确定.仿真实验表明,METrust信任模型可以识别恶意节点,有效提高P2P网络的服务质量.