一类中立型泛函微分方程解的振动定理

给出了二阶中立型泛函微分方程,其中Pi（t）∈C（[t_0，∞），[0，∞）），τ_i＞0（i＝1，2…，m），f（t，u）∈C（[t_0，∞）×R，R）且f（t，0）＝0,g（t,v）∈C（[t_0，∞）×R，R）且的一切解均为振动的必要和充分条件。     

几类可化为常微分方程求解的积分方程(组)

本文提出了若干可化为一阶、n阶(n≥2)常微分方程求解的积分方程(组)的类型,并给出了解的表达式,应用其公式,可简化求相应方程(组)解的演算过程,还对文献中的有关问题作了总结与推广。     

随机系数代数方程平均实根个数的估计

考虑随机系数代数方程 F_n(w,t)= _0(w) _1(w)t … _(n-1)。(w)t~(n-1)=0,其中 _i(w)(i=0,1,…,n-1)为独立且服从标准正态分布的随机变量。令EN_F,(w)表示 F_n(w,t)的平均实根个数。本文证明了EN_F(w)<2/πln n-2/(nπ) 1.2372771。     

计算机网络安全与防火墙技术

计算机网络的不断发展,加快了我国企业和全社会信息化的脚步,同时网络安全问题已成为信息时代人类共同面临的挑战,网络安全问题也日益突出。全面分析了目前计算机网络安全问题,探讨了网络安全策略,通过主要的防火墙技术来分析如何提高网络安全性能,从而保证网络的安全。     

The effect of school resources on pupil attainment: a multilevel simultaneous equation modelling approach

Summary.  Improving educational achievement in UK schools is a priority, and of particular concern is the low achievement of specific groups, such as those from lower socio-economic backgrounds. An obvious question is whether we should be improving the outcomes of these pupils by spending more on their education. The literature on the effect of educational spending on the achievement of pupils has some methodological difficulties, in particular the endogeneity of school resource levels, and the intraschool correlations in pupils' responses. We adopt a multi-level simultaneous equation modelling approach to assess the effect of school resources on pupil attainment at age 14 years. The paper is the first to apply a simultaneous equation model to estimate the effect of school resources on pupils' achievement, using the newly available national pupil database and pupil level annual school census.     

新城市社会学的空间转向

新城市社会学是都市研究的替代范式,其间展现的空间转向是新城市社会学有别于“旧”的城市社会学的重要纬度。本论文旨在透过“空间转向”这一特定的层面把握新城市社会学的理论脉络。     

光热反射实验中微弱信号的测量

介绍了用激光光热反射方法测量表面下物体热物性的实验原理.分析了实验中噪声的主要来源,运用带通滤光片结合差分探测的方式降低激光器产生的噪声.锁相放大技术对被测信号进行窄带放大,锁相放大器结合示波器输出了被测信号的周期变化部分,实现了光热法测量中微弱信号的测量.     

A new family of random graphs for testing spatial segregation

The authors discuss a graph‐based approach for testing spatial point patterns. This approach falls under the category of data‐random graphs, which have been introduced and used for statistical pattern recognition in recent years. The authors address specifically the problem of testing complete spatial randomness against spatial patterns of segregation or association between two or more classes of points on the plane. To this end, they use a particular type of parameterized random digraph called a proximity catch digraph (PCD) which is based on relative positions of the data points from various classes. The statistic employed is the relative density of the PCD, which is a U‐statistic when scaled properly. The authors derive the limiting distribution of the relative density, using the standard asymptotic theory of U‐statistics. They evaluate the finite‐sample performance of their test statistic by Monte Carlo simulations and assess its asymptotic performance via Pitman's asymptotic efficiency, thereby yielding the optimal parameters for testing. They further stress that their methodology remains valid for data in higher dimensions.     

英语空间词语OVER的认知语义研究

从认知角度对英语空间概念词语OVER的语义进行分析,其理论前提是:比喻是人类认识世界的重要手段;空间概念主要是通过隐喻,即空间隐喻表达的。空间隐喻是一种意象图示——以空间概念为始原域,构建其它非空间的目标域。因此,一个表示空间概念的词语其词义往往在原型意义——空间意义的基础上经隐喻拓展而获得许多新的抽象的意义。     

长波电台和联合舰队问题没有涉及国家主权吗?——与沈志华先生商榷

上世纪50年代末期,苏联提议中苏两国共同组建长波电台和潜艇联合舰队,为了维护国家主权,中方与苏方发生了激烈的争论和斗争。最近沈志华先生根据有关资料提出长波电台和联合舰队问题没有涉及国家主权。这一观点显然是不能成立的。