湖南省雷暴与闪电时空分布特征对比分析

本文结合湖南气候特点,选取2008-2010年08、14、20时正点观测的当前天气现象中的雷暴数据,与正点观测时前15min测站15km和20km半径内发生的闪电数据进行对比分析,通过对比两者间的关系,得到湖南省的雷暴日及闪电的时空分布特点是：春季、夏季为湖南的雷电高发期,这与湖南的春、夏的气候特点吻合,但就闪电密度分布与年均雷暴日的空间分布上看,两者的区别较大,需要做进一步的分析。     

移动边缘计算增强的超密集网络上行传输性能分析与基站配置设计

在引入移动边缘计算(MEC)技术的超密集网络(UDN)中,网络性能受无线传输链路质量和基站计算资源部署的共同影响。本文以小型基站接收干扰信号的统计特性分析为基础,对UDN与MEC结合场景的上行空间遍历容量进行分析,并根据空间业务强度和小基站计算服务排队系统的稳定性约束关系,进行小基站配置设计。首先,采用空间泊松点过程对干扰源用户分布进行建模,同时考虑无线信道的多天线与小尺度衰落特性,以小基站部署密度为变量分析上行用户信干比的统计特性及变化规律;然后,根据排队论计算空间业务强度与MEC服务器计算能力之间的约束关系;最后,采用数值仿真验证了信干比与基站密度关系分析的正确性,得出了空间遍历容量的收敛趋势,并给出了小基站与MEC服务器配置设计的例子。     

基于MODIS数据的去云处理实现方法

地表温度是监测地球资源环境动态变化的重要指标,精确定量反演陆面温度并分析温度变化趋势对旱灾预报、农作物产量估算、生态环境变化及区域规划等人们的生产生活方面具有重要研究意义。利用卫星遥感资料进行面状区域地表温度的同步快速获取已成为目前遥感定量研究中的重要任务之一。本文选取长三角05年全年46幅8天合成的地表温度产品数据MYD11A2,基于MODIS数据温度产品会涉及到云污染而导致数据缺失的问题,引入HANTS方法进行去云处理,为地表温度与下垫面关系时空分析奠定基础。     

养殖密度对鱼类福利影响研究进展

水产养殖密度是现代集约化养殖生产过程中十分重要的生产管理要素,不合理的养殖密度易使鱼类长期处于应激胁迫之中,从而影响到鱼类福利水平,增大养殖管理风险。目前国际上对鱼类福利养殖的密度问题十分重视并广泛开展研究。本文将重点阐述鱼类表观现象,如生长状况、健康状态、应激反应和行为特征等指示因子,对养殖鱼类福利进行密度评估,以探讨最佳养殖密度和向生产者提供有实际参考意义的技术理论。     

船用无线定位仪发展因素以及增长特点分析

自改革开放以来,随着精神文化与物质生活水平提高,航海事业得到了快速发展,船用无线电定位仪在沿海渔区也呈现出良好的上升趋势。本文结合我国船用无线电定位仪,对船用无线定位仪发展因素以及增长特点进行简要分析。     

芦潮港海上风资源变化特性分析

海上风资源特性对海上风电场的建设具有重大影响,是海上风机选型及排布的关键因素,因此对其进行研究十分必要。利用测风塔测量得到上海芦潮港地区风速数据,并分析了该地区风速、风向、风能密度分布及其变化特性。结果表明：在芦潮港地区海上风速分布描述上,Logistic函数具有最好的精度,Weibull函数很难描述单月风速分布;芦潮港地区风向主要来自正北与东北方向;随着芦潮港地区测风塔测风高度的增加,年平均海上风速逐步趋于8 m/s;芦潮港地区年平均风能密度不低于290 W/m2,具有较为充足的风能资源,可为风电场收益提供保障。     

稀相气-固流化床分选电厂磨机返料中黄铁矿的实验与模拟

为了降低燃煤电厂的磨机功耗,减少锅炉燃烧后的污染排放,通过分析磨煤机分离器返料的粒度和密度分布,对电厂采样物料进行稀相流化床分选去除黄铁矿等矿物质的实验研究,并对物料分选过程进行数值模拟。结果表明,粒径小于0.500 mm的分离器返料在流化床中具有较小的起始流化速度1.62 cm/s,流化床各层的密度和粒度具有很好的稳定性;物料中的黄铁矿等矿物质得到分离,上层和底层物料灰分质量分数分别为33.34%、73.42%,硫分质量分数分别为1.12%、8.96%,底层物中硫主要以黄铁矿的形式存在;气-固两相流稀相分选床的流场形态及颗粒运动数值模拟验证了实验结论。     

嵌入式共固化复合材料夹芯板结构的自由振动

基于一阶ZIG-ZAG理论和夹芯层的常复数模型,采用Navier解形式对铺层方式为(0°/90°/0°)的薄的四边简支三层夹芯板的自由振动进行分析。研究了在夹芯板总厚度不变的前提下,固有频率随着表层厚度的增加呈现先减小后增大的趋势,呈上凹抛物线状;损耗因子值随着表层厚度的增加呈现先增大后降低的趋势,分布呈下凸抛物线状,最大值出现在表层和底层厚度相等时,因此对称结构夹芯板为最优结构设计;在夹芯层厚度和位置一定的前提下,固有频率的值随着表层和底层厚度的增加而增大,损耗因子值随着表层和底层厚度的增加呈现先增加后减小的趋势,损耗因子存在最大值,为夹芯板结构的最优设计提供参考。     

辽河流域河流健康综合评价方法研究

根据2009年5月太子河流域水生生物（藻类、鱼类和大型底栖动物）调查结果,以藻类、鱼类、大型底栖动物、基本水质和营养盐作为候选参数,采用总体线性回归模型和相关性分析法对它们进行筛选,构建了多指标河流健康综合评价指数,对辽河流域河流健康进行了评估。结果表明,辽河流域河流健康受损较重,未达到“良”等级的样点有146个,所占比例高达83 %,主要分布在浑河、东辽河和西辽河流域,这些流域受到来自城市、工业及农业面源污染较大;“良”等级的样点只有30个,主要分布在太子河流域上游地区,这些样点受到人类干扰较少;整个流域鱼类类群存在显著退化趋势,其中西辽河的鱼类类群衰退现象最明显。     

预制体尺度对C/C复合材料CVI增密过程影响的模拟研究

对不同直径圆柱预制体的CVI增密过程进行数值模拟研究,分析预制体尺度对增密过程及密度分布 的 影 响。针 对 高90mm,直 径 分 别 为60、120、180mm的预制体,分别模拟CVI过程中预制体的孔隙率、密度以及孔隙平均尺寸分布和变化特征。结果显示,小直径预制体经过一段时间的沉积后密度分布较为均匀,且平均密度值很高;预制体直径较大时,沉积易发生在表面区域,导致表面区域密度较高,中心区域密度值较低,影响进一步的增密过程。     

一种时空权重和边缘自适应的扫描格式转换

为实现隔行扫描到逐行扫描的视频扫描格式转换,提出了一种时空权重和边缘自适应的去隔行算法,主要包括运动估计、小角度边缘搜索、时空权重计算、自适应插值等。该算法通过4场相邻像素的最大灰度变化与运动阈值比较实现对当前像素的运动估计,采用自适应搜索半径和并行搜索树的方法实现小角度边缘检测,并且增加对半像素边缘的考虑实现最小6°边缘的检测,最后通过时空权重自适应的插值算法实现去隔行处理,取得很好的处理效果。     

东海区海表温度与中上层渔获量关系的时空分析

从GIS的空间分析的角度研究渔业产量同海洋环境要素的关系 ,结合东海区( 118.5°～ 130°E ,2 4°～ 36°N) 1987～ 1998年的海表温度场及同期的中上层鱼类的渔获量数据 ,定量地刻划出温度场与温度梯度场分别与渔捞量之间关系 ,并进一步寻找渔场同环境要素之间关系的空间变化规律     

Spatio‐Temporal Surveillance Using CUSUM of Order Statistics

The scan statistic is a popular choice for monitoring and detecting spatio‐temporal outbreaks. It can be designed to be optimal if the outbreak characteristics (shape and size) are known in advance. However, in all practical situations, neither the shape nor the size are known in advance. Therefore, there is a need for spatio‐temporal surveillance plans that perform well for a range of unknown outbreaks. This paper proposes a new approach for detecting spatio‐temporal outbreaks based on the cumulative sum of order statistics. The approach performed on average better than the simple scan statistic for both a range of outbreaks involving a single geographical region. More importantly, it performed significantly better than the simple scan plan for outbreaks involving simultaneous multiple (non‐overlapping) geographically dispersed regions. Copyright © 2014 John Wiley & Sons, Ltd.     

Child pedestrian casualties and deprivation

The existence of an association between child pedestrian accidents and socio-economic deprivation in Great Britain is well established. The factors driving this association are complex and difficult to isolate. This study uses accident prediction models to investigate the links between child pedestrian casualties and a range of environmental and socio-economic factors commonly linked to deprived areas and people. Separate models are constructed relating to the areas in which the children become casualties, and the areas in which the children reside. Significant socio-economic factors include: single-parenthood, reliance on income support, and crime; and environmental factors include domestic garden area, junction density and pedestrian and vehicular flow density. The study found that factors pertaining to the local environment were more prevalent in the models considering accident locations, whilst socio-economic factors were of greater influence in the residency model.     

Stabilizing management of fishery resources in a fluctuating environment

We consider the problem of stabilizing the management of uncertain fishery resources. Stabilizing management policies are designed on the basis of memoryless state feedback-control strategies for a class of discrete-time resource models, which contain unknown but bounded fluctuations. The theory is based on conditions developed for a Lyapunov-type stability of sets. The theory is illustrated by simulation examples from fisheries econimics. Parent stock is stabilized by a feedback harvesting strategy, when the catchability of the resource or the stock-recruitment relationship fluctuates. Entry and exit of fishermen are stabilized in an open-access common-property fishery, where the entry and exit dynamics are determined by fluctuating revenues obtained from the fishery.     

Diagnostic analysis of the logistic model for pedestrian injury severity in traffic crashes

This study attempts to evaluate the injury risk of pedestrian casualties in traffic crashes and to explore the factors that contribute to mortality and severe injury, using the comprehensive historical crash record that is maintained by the Hong Kong Transport Department. The injury, demographic, crash, environmental, geometric, and traffic characteristics of 73,746 pedestrian casualties that were involved in traffic crashes from 1991 to 2004 are considered. Binary logistic regression is used to determine the associations between the probability of fatality and severe injury and all contributory factors. A consideration of the influence of implicit attributes on the trend of pedestrian injury risk, temporal confounding, and interaction effects is progressively incorporated into the predictive model. To verify the goodness-of-fit of the proposed model, the Hosmer–Lemeshow test and logistic regression diagnostics are conducted. It is revealed that there is a decreasing trend in pedestrian injury risk, controlling for the influences of demographic, road environment, and other risk factors. In addition, the influences of pedestrian behavior, traffic congestion, and junction type on pedestrian injury risk are subject to temporal variation.     

基于CBR的中心渔场预报

针对海洋渔业遥感信息与资源评估服务系统中中心渔场预报的问题,提出了一种多策略的基于CBR的趋势预测方法,通过不同的相似性度量方法,复用完全相似或者条件相似的历史序列,利用领域专家规则对预报结果进一步修正,取得了较好的预防结果,相关系统正在应用推广之中。     

中国海洋渔业可持续发展及其高技术需求

文章根据中国海洋渔业发展现状和影响可持续发展的主要问题,提出了海洋渔业可持续发展需要支持的5项高技术研究。     

Exploring the influential factors in incident clearance time: Disentangling causation from self-selection bias

Understanding the relationships between influential factors and incident clearance time is crucial to make effective countermeasures for incident management agencies. Although there have been a certain number of achievements on incident clearance time modeling, limited effort is made to investigate the relative role of incident response time and its self-selection in influencing the clearance time. To fill this gap, this study uses the endogenous switching model to explore the influential factors in incident clearance time, and aims to disentangle causation from self-selection bias caused by response process. Under the joint two-stage model framework, the binary probit model and switching regression model are formulated for both incident response time and clearance time, respectively. Based on the freeway incident data collected in Washington State, full information maximum likelihood (FIML) method is utilized to estimate the endogenous switching model parameters. Significant factors affecting incident response time and clearance time can be identified, including incident, temporal, geographical, environmental, traffic and operational attributes. The estimate results reveal the influential effects of incident, temporal, geographical, environmental, traffic and operational factors on incident response time and clearance time. In addition, the causality of incident response time itself and its self-selection correction on incident clearance time are found to be indispensable. These findings suggest that the causal effect of response time on incident clearance time will be overestimated if the self-selection bias is not considered.     

Creating “Smart” Surfaces Using Stimuli Responsive Polymers

Surfaces modified with stimuli‐responsive polymers (SRPs) dynamically alter their physico‐chemical properties in response to changes in their environmental conditions. The triggered control of interfacial properties provided by immobilized SRPs at the solid–water interface has application in the design of biomaterials, regenerable biosensors, and microfluidic bioanalytical devices. In this article, we briefly summarize recent research in this area, followed by two recent examples of research from our laboratory on stimuli‐responsive surfaces. First, we present a new assay to quantify the phase transition behavior of SRPs at the solid–water interface. This assay, which is based on the distance‐dependent colorimetric properties of gold nanoparticles, provides a technically simple and convenient method to determine the effect of different variables on the lower critical solution temperature (LCST) behavior of SRPs at the solid–water interface. Second, we show that stimuli‐responsive surfaces can be created by the immobilization of an elastin‐like polypeptide (ELP), a thermally responsive biopolymer, on a glass surface. We exploit the phase transition of the ELP at a surface to reversibly address an ELP fusion protein to a surface. This method, which we term thermodynamically reversible addressing of proteins (TRAP), enables the reversible, spatio‐temporal modulation of protein binding at the solid‐liquid interface, and will enable the realization of new bioanalytical applications.