国内外流感监测系统的地理流行病学比较研究

流感监测系统的建立是应对流感大流行的一种极为有效的举措。为此,美国、加拿大、墨西哥、巴西、英国、欧盟、俄罗斯、澳大利亚、新西兰、中国等国家,先后都建立了自己的流感监测系统。为了提高我国流感监测系统的水平,作者选出代表性强、特色显著的美国、欧洲和我国的流感监测系统作为典型,从地理流行病学的角度,着重对流感监测及其数据分析的地理分区、流感疫情动态变化的评价标准等方面进行了比较研究。通过总结先进国家的成熟经验,结合我国的实际情况和需求,作者对我国的流感监测系统提出了改进意见。在综合考虑我国地貌特点、气候分区和管理需要的基础上,建议将现有以秦岭淮河为界划分的南、北两个地理分区,细化为黑吉辽区、京津冀鲁豫区、长江中下游区、闽粤桂琼台区、蒙甘新区、晋陕宁区、渝黔川滇区和青藏区等8个流感监测地理分区;建议将现有流感监测系统引入基于流感样病例占门诊病例百分数的基线,利用归因肺炎及流感的死亡率,计算流感季节基线和流行阈值,以客观地衡量和评价流感流行水平及其严重程度。这些研究成果,不仅对地理流行病学的发展有理论意义,而且也对流感及其他传染病的监测有实用价值。     

Crime in Urban Post-Disaster Environments: A Methodological Framework from New Orleans

This paper considers the interrelationship between residential occupancy status, blight, and crime. An analytical frame is provided for a fine-scale analysis that is sufficiently flexible to capture both spatial and temporal dynamism in field-collected data. Unlike other works linking crime to evidence of disorder within neighborhoods, this paper considers this relationship in terms of neighborhoods affected by an external event (natural disaster), which results in more dynamic spatial and temporal patterns as the neighborhood is in a state of flux. As a result, new means of data collection and analysis are required, as any fine-scale relationship is longitudinal as well as cross sectional. The focus here is on the interrelationship of post-disaster residential occupancy, building conditions, and crime incidence for the Holy Cross neighborhood of New Orleans as it recovers from Hurricane Katrina. Results suggest that crime is inversely related to the amount of activity on a recovering street.     

基于改进SIFT算法的视频图像序列自动拼接

本文提出了一种自适应帧采样和限定特征提取区域的拼接方法,根据帧间重叠率和帧间隔建立线性模型,并把各帧图像对准到其前后的关键帧上。在特征点提取方面,提出了一种改进的SIFT算法进行特征点提取,并采用随机采用一致性(RANSAC)方法来更新匹配点,在图像融合中采用线性加权渐入渐出的自然融合算法。实验结果表明:该方法对一般场景能稳定的抽取到关键帧,并进行拼接,取得了较好的拼接效果。     

System structure and calibration models of intelligent photogrammetron

This paper describes the structure, geometric model and geometric calibration of Photogrammetron I—the first type of photogrammetron which is designed to be a coherent stereo photogrammetric system in which two cameras are mounted on a physical base but driven by an intelligent agent architecture. The system calibration is divided into two parts: the in-lab calibration determines the fixed parameters in advance of system operation, and the in-situ calibration keeps tracking the free parameters in real-time during the system operation. In a video surveillance set-up, prepared control points are tracked in stereo image sequences, so that the free parameters of the system can be continuously updated through iterative bundle adjustment and Kalman filtering.     

The interannual variability of megafaunal assemblages in the Arctic deep sea: Preliminary results from the HAUSGARTEN observatory (79°N)

Although megafaunal organisms play an important role in deep benthic ecosystems and contribute significantly to benthic biomass in the Arctic little is known about their temporal dynamics. Here, we assessed the interannual dynamics of megafaunal organisms from the HAUSGARTEN observatory in the Fram Strait, an area where the effects of climatic forcing are particularly evident. We analysed three congruent camera transects taken in 2002, 2004 and 2007. Environmental parameters were measured in order to be able to put our faunal results into an environmental context.Our results indicate that although the densities of megafaunal species show different patterns over time, most exhibit an overall decrease between 2002 and 2007 and total megafaunal densities decreased regularly from 2002 to 2004 to 2007 (12.16±0.96 to 7.41±0.43 ind m⁻²). This concurs with a steady increase in bottom-water temperatures and a decrease in the total organic content and microbial biomass of surficial sediments at the same time period. Although suspension feeder densities also decreased, predator/scavenger and deposit feeder densities have declined to such an extent that suspension feeders accounted for almost 100% of the megafauna in 2007. It could thus be argued that the trophic diversity at the central HAUSGARTEN station (2500 m) has decreased. Temperature-related changes in the production of the surface layers may lead to changes in the quality and/or quantity of particles exported to the deep seafloor. The densities of deposit feeders (i.e. holothurians) peaked (1.14±0.13 ind m⁻²) in 2004, the year following the longest ice cover. These results indicate the importance of ice-related export of particles to the deep seafloor and highlight the need for time-series transects, especially in an era when productive marginal ice zones tend to disappear with the receding sea ice. Although there is a general consensus that the Arctic is in a transition towards a warmer state, only continued observation will allow us to assess if the interannual changes observed are a result of decadal cycles related to the Arctic and North Atlantic Oscillation or if they are indicators of long-term change.     

目标跟踪中参考模型的自动初始化方法

目标跟踪中参考模型的初始化大多需要手动完成,现有的自动初始化方法也存在明显缺陷,针对这些问题提出了一种自动、精确初始化参考模型的方法。首先采用连通组分标记算法对目标进行计数,并计算每个目标的位置;然后根据回转半径张量法求出包含目标的最小外接矩形;最后从最小外接矩形的参数出发用蒙特卡洛算法求出参考模型的估计。实验结果表明在不同的场景下算法均能准确完成参考模型的初始化,计算出的模型能够体现目标的视觉特征。     

TomoSAR技术在城市形变监测中的应用

作为永久散射体雷达干涉测量技术的延伸,多基线SAR层析成像技术能够分离单个SAR像素内的多重散射体信号,精确地获取人工地物目标的三维位置和形变信息,突破城市地区形变监测中叠掩效应的制约,实现城市动态形变监测。尤其是新代高分辨军SAR卫星发射成功后,为城市动态形变监测研究提供了大量高分辨军高精度数据源。本文首先介绍SAR层析技术的理论模型,然后归纳了现有的层析算法和应用领域,最后探讨了该技术发展面临的关键问题并展望了其广阔发展前景。     

时空域相关性的快速HEVC帧问模式判决方法

高性能视频编码（HEVC）相比目前的国际视频编码标准H．264／AVC有着更高的视频压缩比,但同时也带来了更大的编码计算复杂度。为了降低该计算复杂度,提出了一种快速HEVC帧间预测模式。统计了HEVC中最大出现概率的预测单元（PU）模式,分析了相邻两帧之间的编码单元（CU）和Pu之间的时域相关性,分析了对应CU分块与其空间上相邻的4个CU之间的相关性。根据分析的最大出现概率的Pu模式,以及时域相关性和空域相关性,跳过当前最大编码单元中各层CU中冗余的Pu模式,从而降低了编码的计算复杂度。实验结果显示,与HEVC测试模型HM7．0相比,该算法能在保持视频质量和视频压缩比基本不变的情况下,降低32．2％～52．4％的编码时间。     

云南地震重点监视防御区震害异常软弱岩土的调查研究

通过分析云南历史破坏性地震震害异常影响因素,得出第四系软弱土层和新近系禽煤岩层等软弱岩土因素是显著影响云南历史地震震害异常的原因。利用1：20万（中比例尺）地质及水文地质资料,对云南地震重点监视防御区软弱岩土进行调研,得到软弱岩土的分布状况．并初步分析了软弱岩土的分布特征。同时,通过分析对覆盖整个昆明盆地的新生代沉积相作过较详细研究工作的1：5万地质资料,得到昆明盆地软弱土的分布及特征。     

一种适用于视频全站仪的数码相机检校方法

直接线性变换法是相机检校中常用的一种方法,在此基础上提出一种可应用于视频全站仪的数码相机检校方法,通过改变像方元素的单位,就可不必考虑标准单位和像素单位间的转化因子问题。进一步讨论了像素尺寸大小对系统误差的影响,并对像素大小的必要测定精度进行了公式推导。试验结果表明,该方法可以获得较好的校准结果。