基于潮流能直驱式海水淡化系统的建模与仿真

提出使用捕能系统捕获潮流能带动低压海水泵把低压海水转换为高压海水进行海水淡化,并对海水淡化过程中的浓海水进行能量回收。潮流能海水淡化关键在于提高效率和进入海水淡化系统时的海水压力的稳定。潮流能海水淡化系统采用直驱方式和能量回收系统提高了潮流能转换效率,而且系统中的高、低压蓄能器对海水淡化过程中海水压力起着稳定的作用。基于线性流体力学理论,推导出潮流能直驱式海水淡化系统的数学模型,模型考虑了水液压系统内部件的滑动摩擦力和泄露量。并对数学模型在系统压力、产水量和产水比能耗等方面进行仿真。仿真结果达到系统压力稳定、产水比能耗低。     

遥感影像低秩信息的矩阵填充复原方法

提出一种基于矩阵填充的遥感低秩信息复原方法,通过"确定性采样"与"热启动技术",利用奇异值阈值迭代收缩算子进行了椒盐噪声去除与去厚云修复试验.试验表明,本文方法对于因污染或遮挡等原因造成的信息缺损问题的复原效果占优,其在信息复原的同时能较好地保留细节纹理信息并保持图像结构的连贯性.此法可用于遥感影像椒盐类孤立的点状噪声去除与厚云修复复原中,尤其是当影像矩阵具备区域结构内容相似性及纹理规则等低秩特征时,这种复原效果更佳.     

基于下一代四星转轮式编队系统精确和快速反演FSCF地球重力场

第一,由于重力卫星编队轨道的稳定性设计是建立下一代高精度和高空间分辨率地球重力场模型的关键,因此为保证下一代四星转轮式编队系统的稳定性,轨道根数的最优设计如下:(1)轨道半长轴a、轨道偏心率e、轨道倾角i和升交点赤经Ω保持不变;(2)每对卫星的近地点幅角ω和平近点角M分别相差180°;(3)初始近地点辐角ω设置于赤道处,初始平近点角M设计于极点处;(4)卫星编队系统椭圆轨道的半长轴和半短轴之比为2:1. 第二,基于下一代四星转轮式编队系统,利用星间速度插值法,通过相关系数(激光干涉测量系统的星间速度0.85、GPS接收机的轨道位置和轨道速度0.95、星载加速度计的非保守力0.90)、观测时间30天和采样间隔10 s,反演了120阶FSCF-1/2/3/4(Four-Satellite Cartwheel Formation)地球重力场,在120阶处累计大地水准面精度为1.162×10^-4 m,较目前GRACE地球重力场精度至少提高一个数量级. 第三,下一代四星转轮式编队系统具有低轨道高度、高精度测量、全张量观测、弱混频效应和强时变信号的优点.     

A probabilistic approach for the prediction of seismic resilience of bridges

This paper proposes a probabilistic approach for the pre‐event assessment of seismic resilience of bridges, including uncertainties associated with expected damage, restoration process, and rebuilding/rehabilitation costs. A fragility analysis performs the probabilistic evaluation of the level of damage (none, slight, moderate, extensive, and complete) induced on bridges by a seismic event. Then, a probabilistic six‐parameter sinusoidal‐based function describes the bridge functionality over time. Depending on the level of regional seismic hazard, the level of performance that decision makers plan to achieve, the allowable economic impact, and the available budget for post‐event rehabilitation activities, a wide spectrum of scenarios are provided. Possible restoration strategies accounting for the desired level of resilience and direct and indirect costs are investigated by performing a Monte Carlo simulation based on Latin hypercube sampling. Sensitivity analyses show how the recovery parameters affect the resilience assessment and seismic impact. Finally, the proposed approach is applied to an existing highway bridge located along a segment of I‐15, between the cities of Corona and Murrieta, in California. Copyright © 2013 John Wiley & Sons, Ltd.     

月面巡视探测器立体影像的多核CPU并行快速匹配

月面巡视探测器立体影像的摄影测量处理是获取月面三维信息实现巡视器定位导航的重要手段之一。影像匹配是地面近景摄影测量实现自动化处理的关键,本文研究了基于积分影像的单机多核并行匹配算法,实现了月面巡视器模拟影像的快速匹配。试验表明该方法能显著地缩短匹配时间,达到较高的加速比和效率。     

Mapping post-fire forest regeneration and vegetation recovery using a combination of very high spatial resolution and hyperspectral satellite imagery

Careful evaluation of forest regeneration and vegetation recovery after a fire event provides vital information useful in land management. The use of remotely sensed data is considered to be especially suitable for monitoring ecosystem dynamics after fire. The aim of this work was to map post-fire forest regeneration and vegetation recovery on the Mediterranean island of Thasos by using a combination of very high spatial (VHS) resolution (QuickBird) and hyperspectral (EO-1 Hyperion) imagery and by employing object-based image analysis. More specifically, the work focused on (1) the separation and mapping of three major post-fire classes (forest regeneration, other vegetation recovery, unburned vegetation) existing within the fire perimeter, and (2) the differentiation and mapping of the two main forest regeneration classes, namely, Pinus brutia regeneration, and Pinus nigra regeneration. The data used in this study consisted of satellite images and field observations of homogeneous regenerated and revegetated areas. The methodology followed two main steps: a three-level image segmentation, and, a classification of the segmented images. The process resulted in the separation of classes related to the aforementioned objectives. The overall accuracy assessment revealed very promising results (approximately 83.7% overall accuracy, with a Kappa Index of Agreement of 0.79). The achieved accuracy was 8% higher when compared to the results reported in a previous work in which only the EO-1 Hyperion image was employed in order to map the same classes. Some classification confusions involving the classes of P. brutia regeneration and P. nigra regeneration were observed. This could be attributed to the absence of large and dense homogeneous areas of regenerated pine trees in the study area.     

Coping with floods: preparedness,response and recovery of flood-affected residents in Germany in 2002

Abstract

In August 2002, a severe flood event occurred in Central Europe. In the following year, a poll was performed in Germany in which 1697 private households were randomly selected from three regions: (a) the River Elbe area, (b) the Elbe tributaries in Saxony and Saxony-Anhalt, and (c) the Bavarian Danube catchment. Residents were interviewed about flood characteristics, early warning, damage, recovery, preparedness and previously experienced floods. Preparedness, response, financial losses and recovery differed in the three regions under study. This could be attributed mainly to differences in flood experience and flood impact. Knowledge about self-protection, residents' home-ownership and household size influenced the extent and type of private precautions taken, as well as the residents' ability to perform mitigation measures. To further improve preparedness and response during future flood events, flood warnings should include more information about possible protection measures. In addition, different information leaflets with flood mitigation options for specific groups of people, e.g. tenants, homeowners, elderly people or young families, should be developed.     

Multi-objective optimization for free-phase LNAPL recovery using evolutionary computation algorithms

Abstract

A nonlinear, multi-objective optimization methodology is presented that seeks to maximize free product recovery of light non-aqueous phase liquids (LNAPLs) while minimizing operation cost, by introducing the novel concept of optimal alternating pumping and resting periods. This process allows more oil to flow towards the extraction wells, ensuring maximum free product removal at the end of the remediation period with minimum groundwater extraction. The methodology presented here combines FEHM (Finite Element Heat and Mass transfer code), a multiphase groundwater model that simulates LNAPL transport, with three evolutionary algorithms: the genetic algorithm (GA), the differential evolution (DE) algorithm and the particle swarm optimization (PSO) algorithm. The proposed optimal free-phase recovery strategy was tested using data from a field site, located near Athens, Greece. The PSO and DE solutions were very similar, while that provided by the GA was inferior, although the computation time was roughly the same for all algorithms. One of the most efficient algorithms (PSO) was chosen to approximate the optimal Pareto front, a method that provides multiple options to decision makers. When the optimal strategy is implemented, although a significant amount of LNAPL free product is captured, a spreading of the LNAPL plume occurs.

Editor Z.W. Kundzewicz; Associate editor L. See

Citation Dokou, Z. and Karatzas, G.P., 2013. Multi-objective optimization for free-phase LNAPL recovery using evolutionary computation algorithms. Hydrological Sciences Journal, 58 (3), 671–685.     

SZW-1A型数字式温度计（V2004）通讯故障诊断及排除

基于SZW．1A型数字式温度计（V2004）的维护管理经验和仪器组成,对SZW．1A型数字式温度计（V2004）的通讯故障原因进行了研究。结果表明,导致SZW-1A型数字式温度计（V2004）通讯故障的主要原因有网络链路故障、网络通讯接口故障和仪器主机故障3大类。针对SZW-1A型数字式温度计（V2004）常见非网络链路通讯故障的判定提出了一套诊断流程,并提出了该型号数字式温度计常见通讯故障的排除方法。这些故障的排除方法,对和SZW-1A型数字式温度计（V2004）有类似硬件组成的SWY-1A型水位仪、SWY-Ⅱ型水位仪、SWDW-1型水位地温综合观测仪等“十五”流体观测仪器的维护,有一定参考意义。