海洋水声环境调查数据处理系统的设计与实现

针对目前海洋环境调查现状,结合国内现有的技术条件和现有的处理方法、原理,详细论述了海洋水声环境调查处理系统软件主要功能的设计及关键技术,该系统软件满足海洋调查的需求,极大提高了海洋环境数据处理的自动化、数字化和信息化程度。     

Single epoch GPS deformation signals extraction and gross error detection technique based on wavelet transform

IntroductionGPS technique is widely used for deformationmonitoring thanks for the high precision. Usual-ly , there are three working modes associatedwith GPS deformation observation: periodicalGPS deformation monitoring net , GPS monito-ring array and rea…     

On the link between GPS pseudorange noise and day-boundary discontinuities in geodetic time transfer solutions

When neglecting calibration issues, the accuracy of GPS-based time and frequency transfer using a combined analysis of code and carrier phase measurements highly depends on the noise of the GPS codes. In particular, the pseudorange noise is responsible for day-boundary discontinuities which can reach more than 1 ns in the time transfer results obtained from geodetic analysis. These discontinuities are caused by the fact that the data are analyzed in daily data batches where the absolute clock offset is determined by the mean code value during the daily data batch. This pseudorange noise is not a white noise, in particular due to multipath and variations of instrumental delays. In this paper, the pseudorange noise behavior is characterized in order to improve the understanding of the origin of the large day-boundary discontinuities in the geodetic time transfer results. In a first step, the effect of short-term noise and multipath is estimated, and shown to be responsible for only a maximum of 150 ps (picoseconds) of the day-boundary jumps, with only one exception at NRC1 where the correction provides a jump reduction of 300 ps. In a second step, a combination of time transfer results obtained with pseudoranges only and geodetic time transfer results is used to characterize the long-term evolution of pseudorange errors. It demonstrates that the day-boundary jumps, especially those of large amplitude, can be explained by an instrumental effect imposing a common behavior on all the satellite pseudoranges. Using known influences as temperature variations at ALGO or cable damages at HOB2, it is shown that the approach developed in this study can be used to look for the origin of the day-boundary discontinuities in other stations.     

Dendroecological Analysis of Spruce Budworm Outbreaks and their Relation to Climate Near the Prairie-Forest Border in Northwestern Minnesota

This paper investigates the effects of spruce budworm (Choristoneura fumiferana) on balsam fir (Abies balsamea) and white spruce (Picea glauca) at Itasca State Park in northwestern Minnesota. We studied the species composition, age structure, and radial growth patterns in tree rings along five belt transects at sites infested with spruce budworm. Our objectives were to: (1) discover when the latest spruce budworm outbreak started; (2) determine whether tree growth was similarly reduced in earlier decades, suggesting earlier spruce budworm outbreaks; and (3) test whether radial tree growth and the start of the outbreak(s) were correlated with climate. We used the computer program OUTBREAK to determine that the current spruce budworm infestation began to reduce tree growth in the 1990s, before it was detected by park officials in 2001. The tree-ring record indicated that growth of the host-species trees was periodically reduced at all sites prior to the 1990s. We found no consistent relationship between temperature/precipitation and the initiation of spruce budworm outbreaks, as reconstructed by the OUTBREAK program, at the southwestern edge of the distribution of balsam fir. The Palmer Drought Severity Index, however, was positive (i.e., wetter-than-normal conditions) before increased spruce budworm activity at all sites. Outbreaks are related to climatic conditions, but they also depend on other factors such as the availability of sufficient food for the spruce budworm.     

Where do planes fly past overhead? Determining departure and arrival routes from radar traces

This paper questions the main techniques of mapping in the context of aircraft noise in the vicinity of airports, and compares these techniques in terms of their purpose, benefits and limitations. Then the paper describes a method to summarise radar traces of a given air transport departure or arrival route into a median route and its envelope containing 80% of flights. This makes it possible to map global and easy-to-read maps of current air procedures around airports based on actual pathways flown by the aircraft. It also makes it possible to investigate the impact of change in aeronautical procedures on the actual geography of air routes around airports. Such maps complement noise contour maps and offer a good basis for debating aeronautical procedures at airports whose operations expose the population to noise.     

REGIONAL VARIATIONS IN DENOMINATIONAL SWITCHING AMONG WHITE PROTESTANTS*

This study examines the hypothesis that the determinants of denominational switching vary regionally among white American Protestants. Data for the analysis are taken from the National Opinion Research Center's General Social Survey for 1974 through 1984. Using logistic regression, the analysis compares the determinants of switching among respondents residing in the nine Census regions of the U.S. Results reveal significant regional differences in the determinants of switching, especially in the effects of conversion, childhood affiliation and interdenominational marriage.     

作为CAS的复杂城市地理系统的SOC性质

将城市作为复杂适应性系统(CAS)研究其自组织临界性(SOC)具有重要的理论意义和实践价值,这方面的探索工作刚刚开始。本文从城市的地理空间角度出发,论证城市是一种复杂适应性系统。城市在本质上是不可还原的,我们可以根据积木的机制将城市分解,但分解的结果对解释城市的复杂行为丝毫没有帮助。由于城市和城市体系都具有分形结构、服从Z ipf定律,且具有1/f噪声的特征,由此判断城市地理系统具有自组织临界性质。自组织临界性与复杂性适应性立论的视角不同,但可以统一于“混沌的边缘”这一概念。     

中国季降水量的气候噪声和潜在可预报性估计

利用中国130个测站1961—2004年的日降水量资料,使用低频白噪声延伸法和方差分析法估计了中国季降水量的气候噪声方差和潜在可预报性。结果表明：中国季降水量的气候噪声方差由南向北、由沿海向内陆逐渐减小,且有明显的季节变化,夏季最高,其次是春秋季,冬季最小,而且内陆的季节变化比东南沿海的季节变化显著。季降水量的潜在可预报性有较大的季节和区域差异,但总体来说,全国大部分地区的季降水量是潜在可预报的。以绝对误差小于均方差0.68倍作为预测正确标准,全国大部分地区季降水量的预报正确率上限为50%-60%。     

风廓线雷达回波信号强度定标方法

风廓线雷达返回信号功率定标通常通过返回信号信噪比和系统噪声功率的估算得到。该方法存在着噪声电平的确定、外部噪声等不确定性因素,影响了定标的精度。采用信号源分别对接收机和信号处理器进行定量测试,进而对雷达系统进行定标,是另一种可行的办法,该文利用这种方法对CFL-03风廓线雷达进行了定标,并利用该雷达在东莞2009年7月和8月探测资料与广州S波段天气雷达和地面雨量计资料进行比较。结果表明:用该定标方法得到的回波强度与天气雷达回波强度和地面雨量计资料估算的回波强度基本一致,平均标准差在1 dB左右,表明这种定标方法是可行的。     

基于风廓线雷达资料的暴雨天气过程分析

2008年6月1～2日大理市暴雨过程的风廓线雷达资料和每小时的雨量资料分析发现：暴雨过程具有明显的中小尺度系统影响特征,雷达水平风廓线资料可以很直观地显示随时间变化风场的垂直结构;高空气流的向下脉动与降水强度的增强有着紧密的联系;风廓线雷达产品（垂直速度、折射率结构常数和信号噪声比）清楚地反映降水的开始、结束以及降水的强度。