Demographic issues in 1975 and 2000

This article explores the demographic subjects which were topical 25 years ago and compares them with those of current interest, as reflected not only by the articles published in the early, and most recent issues of Population Trends, but also by papers of the period in other demographic journals.     

季节虚假回归中参数及统计量的分布特征

实际应用中,通常在回归模型中添加季节虚拟变量来消除季节性的影响,但是当数据生成过程是独立的季节单位根情形下会导致虚假回归现象的发生.本文利用泛函中心极限定理推导出回归参数及相关统计量的渐近分布,从理论上解释了季节虚假回归问题产生的根源.并且,采用蒙特卡罗方法模拟了回归参数及相关统计量的分布特征.最后,通过与非季节情形进行了比较,发现此时R2和DW统计量不再能有效识别普通最小二乘回归中的“季节虚假回归”现象.     

一种基于高阶统计量的图像识别算法研究

提出了一种基于图像高阶统计量的识别算法。利用Radon变换将图像数据变换到一维空间,通过计算投影数据的双谱构造出具有比例和平移不变性的特征。利用Rapid变换获得特征的旋转不变特性;接着,利用阈值分析的方法进行特征选择,获得了较原始特征更好的识别效果。针对特征向量过长的问题,利用主元分析进行长度压缩。与不同方法的实验比较表明,算法能够有效地用于图像识别。     

宽带宽角扫描相控阵雷达技术研究

针对大型相控阵雷达工作在宽带、宽角扫描的情况下,瞬时信号带宽受孔径度越时间限制的问题,从理论上分析了影响相控阵雷达线瞬时带宽提高的因素和接收通道幅相误差对系统性能的影响,提出了采用射频延迟和视频延迟方法提高相控阵天线瞬时带宽的两种技术途径。并给出在微波暗室里进行的相控阵试验雷达工作在宽带角电扫描情况下成像试验的部分结果,验证了理论分析的正确性。     

基于小波差分统计特征的纹理缺陷检测方法

纹理表面缺陷检测是机器视觉中一个重要研究课题,可广泛应用于纺织品、木材、陶瓷等产品的表面质量控制。针对统计纹理图像,提出了一种小波差分统计纹理特征缺陷检测方法。该方法首先应用小波基函数对纹理图像进行一级分解,将图像划分为互不重叠的子窗口,然后计算其差分统计纹理特征值,最后采用Mahalanobis距离分类器进行缺陷判决。实验不仅证明了该方法的有效性,并表明该方法速度快,可用于实时在线检测。     

Multivariate likelihood ratio ordering of conditional order statistics

Multivariate likelihood ratio order of order statistics conditioned on both the right tail and the left tail are built. These results strengthen and generalize those conclusions in terms of the univariate likelihood ratio order by Khaledi and Shaked (2007), Li and Zhao (2006), Hu, et al. (2006), and Hu, Jin, and Khaledi (2007).     

基于形状统计量的空中目标识别

对直升机和固定翼飞机这两类空中目标多普勒频谱测量能力进行分析,并在测量能力得到满足的前提下,针对目标的多普勒频谱提出了用形状统计量(偏度量和峰度量)作为目标识别的特征。通过对18种直升机和固定翼飞机仿真数据进行检验,证明这种方法是有效的,并且适用于悬停直升机的探测与识别。     

Analysis of linear weighted order statistics CFAR algorithm

CFAR technique is widely used in radar targets detection fields. Traditional algorithm is cell averaging (CA), which can give a good detection performance in a relatively ideal environment. Recently, censoring technique is adopted to make the detector perform robustly. Ordered statistic (OS) and trimmed mean (TM) methods are proposed. TM methods treat the reference samples which participate in clutter power estimates equally, but this processing will not realize the effective estimates of clutter power. Therefore, in this paper a quasi best weighted (QBW) order statistics algorithm is presented. In special cases, QBW reduces to CA and the censored mean level detector (CMLD).     

The demographic situation in the European Union

This article draws selected material from the annual Yearbook on Demography (2000 edition) published by Eurostat, the Statistical Office of the European Communities. Some key comparisons with other regions of the world are included, together with a broad picture of the demographic situation in the European Union. Topic coverage is selective.     

A demographic statistics service for the 21st century

This article provides a summary of a review of the uses made of population and household statistics across government in England and Wales, setting out the policy and statistical impacts of demographic change. It looks at the broad span of government uses of population and household statistics--and what these uses imply for the qualities inherent in these statistics. The article considers alternative population definitions and refers to several ongoing projects that are aiming to enhance demographic statistics in England and Wales. Following an analysis of the key issues relating to the implementation of an improved statistical service, a series of action points for ONS emerging from the review is set out.     

我国发展精确农业若干问题的思考

在介绍精确农业的产生背景以及涵义的基础上,分析了在我国推广和应用精确农业的可能性,指出了我国在发展精确农业中应注意的若干问题,阐述了精确农业与中国生态农业,作物模拟模型和决策支持系统之间的关系,最后对精确农业的发展前景作了展望。参12。     

On-line blind source separation algorithm based on second order statistics

1 .INTRODUCTIONBlindsource separation (BSS) is one of the most activeresearch areasin signal processing community. The mainobjective of blind source separationis to extract indepen-dent source signals fromtheir observed mixtures withoutfull knowledge of the signal propagation environment .BSStechnologies have been widely usedin array process-ing,communications,biomedical signal processing,i mageprocessing, speech processing, seismic prospecting andother areas.Many methods have been prop…     

Performance analysis of multi-channel order statistics detector for range-spread target

The problem of two order statistics detection schemes for the detection of a spatially distributed target in white Gaussian noise are studied.When the number of strong scattering cells is known,we first show an optimal detector,which requires many processing channels.The structure of such optimal detector is complex.Therefore,a simpler quasi-optimal detector is then introduced.The quasi-optimal detector,called the strong scattering cells’ number dependent order statistics(SND-OS) detector,takes the form of an average of maximum strong scattering cells with a known number.If the number of strong scattering cells is unknown in real situation,the multi-channel order statistics(MC-OS) detector is used.In each channel,a various number of maximums scattered from target are averaged.Then,the false alarm probability analysis and thresholds sets for each channel are given,following the detection results presented by means of Monte Carlo simulation strategy based on simulated target model and three measured targets.In particular,the theoretical analysis and simulation results highlight that the MC-OS detector can efficiently detect range-spread targets in white Gaussian noise.     

Implications of changes in the UK social and occupational classifications in 2001 for vital statistics

In 2001, three simultaneous changes were introduced which influence the reporting of vital statistics by socio-economic status. Registrar General's Social Class was replaced by the new National Statistics Socio-Economic Status (NS SEC); the Standard Occupational Classification (SOC) was updated from SOC90 to SOC2000; and the coding of employment status on vital statistics changed to stay in line with census coding and SOC2000. This article reports on these changes and describes a method for coding data prior to 2001 to NS SEC (named NS SEC90) in order to facilitate the analysis of health inequalities over time. NS SEC90 allocates 90 per cent of deaths to the same analytical category as NS SEC. This figure varies according to sub group.     

自然选择与漂变的统计性探析

生物学中的进化论的统计性问题是生物学家和生物哲学家持久争论的问题。作为进化论中重要的理论一自然选择与漂变是双方争论的焦点。双方都希望通过对于自然选择和漂变的解释来证明自己的观点。通过对双方观点的整理比较发现双方的观点都存在着一些问题,而这些问题是否是自然选择和漂变在生物学上不同领域的研究造成了这个结果？因为进化生物学本来就包含着两个不同的研究领域--关于过程的进化生态学和关于结果的群体遗传学。     

模糊随机环境中的欧式障碍期权定价

考虑到现实世界的不确定性包含随机性和模糊性,运用随机分析和模糊集理论研究了模糊随机环境中的欧式障碍期权定价问题.由于各种欧式障碍期权的定价方法和思路基本相同,因此仅以向上敲出看涨障碍期权为例说明如何定价.通过假设标的资产价格服从模糊随机过程,得到了向上敲出看涨障碍期权的模糊价值和其在可能性均值意义下的定价公式.     

Key issues in the quality assurance of the One Number Census

As part of the 2001 Census, the One Number Census project estimated and adjusted the Census database for underenumeration. As a result of the highly innovative One Number Census and the Quality Assurance process it encompassed, it was also ensured that robust results could be obtained for each local authority area. This article examines some of the issues and analyses that were undertaken as part of that assessment of the 2001 Census population counts for England and Wales. The article firstly highlights the key issues surrounding the implementation of the 2001 Census fieldwork. The article then explores the 2001 Census results through a series of demographic analyses to illustrate the sorts of issues investigated during the One Number Census Quality Assurance process itself. These analyses look at the patterns contained within the results, and comparisons with key alternative sources of population counts. Overall, these in-depth analyses and investigations provide further credence to the plausibility of the One Number Census results.     

基于有序统计和自动删除平均的恒虚警检测器

为了增强检测器对干扰的鲁棒性,基于有序统计(OS)方法和自动删除单元平均(ACCA)方法提出一种新的恒虚警检测器(MOSAC),其前沿和后沿滑窗分别采用OS和ACCA产生两个局部估计,然后取二者的和作为背景功率水平估计,从而设置自适应检测门限。在Swerling Ⅱ型目标假设下,推导出MOSAC在均匀背景下虚警概率Pfa的解析表达式,并与其它现有方案进行了比较。仿真结果表明MOSAC在均匀背景及多目标和杂波边缘引起的非均匀背景中,均具有较好的检测性能。在杂波边缘引起的非均匀背景中,虚警尖峰比MOSCM减少了一个数量级,并且样本排序时间只有OS和ACCA的1/2。     

回采工作面安全评价的改进灰色统计方法

用灰色统计理论［１］讨论了煤矿回采工作面安全评价问题，提出了一种新的评价方法——灰色统计综合法。同时，本文从应用的角度出发对灰色统计的算法作了改进，改进后的算法便于记忆和应用。