Optimization of mobile radioactivity monitoring networks

In case of a nuclear accident, decision makers rely on high-resolution and accurate information about the spatial distribution of radioactive contamination surrounding the accident site. However, the static nuclear monitoring networks of many European countries are generally too coarse to provide the desired level of spatial accuracy. In the Netherlands, authorities are considering a strategy in which measurement density is increased during an emergency using complementary mobile measuring devices. This raises the question, where should these mobile devices be placed? This article proposes a geostatistical methodology to optimize the allocation of mobile measurement devices, such that the expected weighted sum of false-positive and false-negative areas (i.e. false classification into safe and unsafe zones) is minimized. Radioactivity concentration is modelled as the sum of a deterministic trend and a zero-mean spatially correlated stochastic residual. The trend is defined as the outcome of a physical atmospheric dispersion model, NPK-PUFF. The residual is characterized by a semivariogram of differences between the outputs of various NPK-PUFF model runs, designed to reflect the effect of uncertainty in NPK-PUFF meteorological inputs (e.g. wind speed, wind direction). Spatial simulated annealing is used to obtain the optimal monitoring design, in which accessibility of sampling sites (e.g. distance to roads) is also considered. Although the methodology is computationally demanding, results are promising and the computational load may be considerably reduced to compute optimal mobile monitoring designs in nearly real time.     

基于贝叶斯最大熵的甘肃省多年平均降水空间化研究

 贝叶斯最大熵方法可以对具有一定不确定性的“软数据”和认为没有误差的“硬数据”进行插值。对甘肃省1961—1990年52个气象站点的多年平均降水数据进行空间化研究。通过比较普通克里格、共协克里格、三元回归建模后残差插值以及基于贝叶斯最大熵的3种不同软硬数据参与情况下的插值结果,发现考虑降水30 a时间序列不完整性以及辅助变量经验模型不确定性的插值结果的MAE和RMSE,比直接使用多年平均降水数据直接插值的MAE和RMSE小,表明贝叶斯最大熵方法通过对不确定性的考虑可以有效降低预测结果的绝对误差。从降水的空间分布来看,考虑辅助变量DEM的插值结果能相对较好的体现高程对降水的地形影响,尤其分区将辅助变量转换为软数据可以有效体现不同区域高程对降水的不同影响问题。综合误差评价以及降水插值结果的空间分布,认为BME插值过程中可以考虑数据本身以及辅助数据利用的不确定性,使降水空间化的结果更加真实客观,同时为合理利用辅助信息提供了一个新思路。     

Propagating error in land-cover-change analyses: impact of temporal dependence under increased thematic complexity

We examined the impact of temporal dependence between patterns of error in classified time-series imagery through a simulation modeling approach. This research extended the land-cover-change simulation model we previously developed to investigate: (1) the assumption of temporal independence between patterns of error in classified time-series imagery; and (2) the interaction of patterns of change and patterns of error in a post-classification change analysis. In this research, the thematic complexity of the classified land-cover maps was increased by increasing the number of simulated land-cover classes. Simulating maps with increased categorical resolution permitted the incorporation of: (1) higher-order, more complex spatial and temporal interactions between land-cover classes; and (2) patterns of error that better reproduce the complex error interactions that often occur in time-series classified imagery. The overall modeling framework was divided into two primary components: (1) generation of a map representing true change; and (2) generation of a suite of change maps that had been perturbed by specific patterns of error. All component maps in the model were produced using simulated annealing, which enabled us to create a series of map realizations with user-defined spatial and temporal patterns. Comparing the true map of change to the error-perturbed maps of change using accuracy assessment statistics showed that increasing the temporal dependence between classification errors did not improve the accuracy of resulting maps of change when the categorical scale of the land-cover classified maps was increased. The increased structural complexity within the time series of maps effectively inhibited the impact of temporal dependence. However, results demonstrated that there are interactions between patterns of error and patterns of change in a post-classification change analysis. These interactions played a major role in determining the accuracy associated with the maps of change.     

A case study of model selection and parameter inference by maximum likelihood with application to uncertainty analysis

One of the uses of geostatistical conditional simulation is as a tool in assessing the spatial uncertainty of inputs to the Monte Carlo method of system uncertainty analysis. Because the number of experimental data in practical applications is limited, the geostatistical parameters used in the simulation are themselves uncertain. The inference of these parameters by maximum likelihood allows for an easy assessment of this estimation uncertainty which, in turn, may be included in the conditional simulation procedure. A case study based on transmissivity data is presented to show the methodology whereby both model selection and parameter inference are solved by maximum likelihood.     

On the statistical mechanics of distributed seismicity

In order to understand the underlying physics of distributed seismicity better we have considered a 2-D array of slider blocks connected by springs and interacting via static friction with a surface. There is no driving plate in this model. The time evolution of the system is found from numerical simulations in a cellular automata formulation. Energy is conserved and is the single control parameter. The distribution of energies in the springs is found to obey a modified Maxwell-Boltzmann statistics. It is found that the number-size statistics of clusters of unstable sliding blocks is identical to those in percolation clusters in the site-to-site percolation model. There is a well-defined critical point when unstable blocks become connected across the array. It has been previously suggested that distributed seismicity in a seismic zone is the percolation backbone of a 3-D percolation cluster. The fact that low-level seismicity satisfies the Gutenberg-Richter frequency-magnitude relation and is nearly constant in time also suggests that this background seismicity is similar to thermally induced noise.     

Application of conditional geostatistical simulation to calculate the probability of occurrence of earthquakes belonging to a seismic series

Geostatistics offers various techniques of estimation and simulation that have been satisfactorily applied in solving geological problems. In this sense, conditional geostatistical simulation is applied to calculate the probability of occurrence of an earthquake with a lower than or equal magnitude to one determined during a seismic series. It is possible to calculate the energy of the next most probable earthquake from a specific time, given knowledge of the structure existing among earthquakes occurring prior to a specific moment.     

黄土高原沟壑区小流域土壤碳酸盐碳的空间分布特征

根据对砖窑沟流域62个点9个层次的取样分析数据，运用地统计学方法探讨了流域土壤碳酸盐碳的空间变异和分布特征。结果表明：除80～100cm层外，其余各层均属中等程度的变异，该变异主要是由空间自相关因素引起的。同层次内，梁峁顶部土壤碳酸盐碳含量最高，沟坝地的含量最低；梁峁顶部和沟坝地较梁峁坡地碳酸盐碳含量变化小。地貌部位不同，碳酸盐碳在剖面上的淀积深度不同。以淀积层为界，沟坝地上部比下部的碳酸盐碳含量略低。梁峁坡地上部与下部的碳酸盐碳含量大体相当，而梁峁顶部上部比下部的碳酸盐碳含量略高。     

昆明市自然旅游资源优化开发探讨

在云南省旅游业蓬勃发展,各地区纷纷将旅游业作为支柱产业重点发展的今天,昆明市作为旅游目的地的功能在减弱,而作为旅游集散地的作用在加强。如何使昆明自然旅游资源得以充分开发,提高其旅游吸引力,是昆明亟德解决的问题,文章从优化开发的角度进行了探讨。     

中国国际集装箱运输网络的布局与优化

在分析世界集装箱运输发展及集装箱网络构成的基础上，指出在海上集装箱运输发展过程中枢纽港与支线港的分离，干线航线与支线航线的形成是集装箱运输发展的必然结果；在陆上，集装箱中转站的分级是集装箱运输发展的客观要求，因此集装箱运输在发展的过程中形成了独特的空间运输网络体系。中国集装箱运输的快速发展在客观上要求合理布局与优化整个集装箱运输网络，在建立了中国集装箱运输GIS系统基础上，提出了中国集装箱港口及集装箱中转站的优化布局，同时提出了在港口与中转站布局基础上形成的中国集装箱运输几个重要运输通道。最后从经济发展对集装箱运输的客观要求出发，用模糊数学的方法，选择典型地区对集装箱运输通道进行不同约束条件下的评价。     

旅游景观生态系统功能优化研究初探

在旅游业迅速发展与快速蔓延的趋势下,如何协调旅游目的地的人地关系,促进区域的可持续发展,是极 具理论与应用价值的科学问题。研究利用景观生态学的基本原理,从要素相互作用关系出发,将旅游景观生态系统 的功能视作各要素相互作用所形成的相应于人类社会需求的表现形式。在此基础上,分析了功能的类型、特征与结 构,总结了功能变化的影响因素,并强调促进要素协调与优化空间配置是实现旅游景观生态系统功能优化研究的 重要途径。     

都市自行车旅游慢行系统空间布局优化研究——以杭州市为例

自行车骑行是旅游者体验目的地城市的重要方式,规划建设高效合理的自行车旅游慢行系统已经成为众多旅游城市共同面临的重要任务。以著名旅游城市杭州为对象,利用实地调查获得的数据和相关研究成果,从空间布局视角分析了杭州自行车旅游慢行系统的发展现状和存在的主要问题,提出了优化和完善自行车旅游慢行系统的对策。结果发现,目前杭州的自行车服务点与休闲旅游点的空间耦合度较低、与旅游流网络特征的协调性较差。最后提出了解决上述问题的主要措施。     

杉木林蓄积量估测的因子选择研究

为提高杉木林蓄积量的估测精度,筛选出对蓄积量有显著解释意义的变量集,本研究采用岭迹分析和逐步回归方法对福建省闽侯白沙国有林场杉木林蓄积量预估模型的主要评价指标因子进行多重相关性研究．结果表明：2种方法对因子的优选结果非常相近,能有效地剔除显著相关的变量,筛选出影响蓄积估测的主要因子信息,为准确估测杉木林蓄积量以及建立预测模型提供方法上的支持．     

淮北城市空间结构演化及优化研究

运用Arcgis软件,将淮北市建市以来4次城市规划用地现状图进行对比,比较了不同时期城市外部形态指数、城市空间扩展规模、扩展速度和扩展强度、各主要用地类型规模及异质性指数。认为淮北城市空间经历了4个发展阶段,外部形态由早期的相对紧凑逐渐走向分散布局,并再次向紧凑布局演化;城市空间以夹符铁路为轴线沿东北—西南——东南向呈"C"形扩展;城市内部的工业用地、居住用地以及商业及公共设施用地规模不断扩张,相互之间也不断取代形成空间重构。从区域竞合关系、资源基础、交通区位、以及城市空间结构现状出发,认为未来淮北城市空间以东向、南向扩展为宜,内部以合理调控各功能用地空间组合、完善城市功能为主。     

关中-天水经济区形成基础及空间结构优化

关中-天水经济区是国家西部大开发"十一五"规划中提出的重点建设的经济区之一,由陕西省的西安、咸阳、渭南、铜川、宝鸡、杨凌五市一区和甘肃省的天水市共同组成。经过两省长期的互补互动,各城市之间相互吸引辐射,空间地域毗邻相连,多种基础设施相通对接,从而形成了相对完整的产业带和经济区。从空间结构理论的角度审视,关中-天水经济区还存在核心不强,区内城市等级体系不完善,地区之间产业趋同、关联度弱等明显制约经济区健康发展的因素,因此,需要通过西安、咸阳两地一体化,建立区域副中心和实施大城市发展战略,城市间实施产业的有序转移和扩散等措施,使关中-天水经济区的空间结构进一步得到优化,以产生特有的结构效益。     

区域交通网络空间结构优化及实证研究

以“绿色交通”为规划理念和区域发展为实践目标,探讨基于GIS的交通网络空间结构优化系统。在对交通问题进行结构分类后,构建载流对比分析模型,对各交通类型进行评估,测算区域综合承载能力。以河南省为研究区域,进行交通载流对比分析,评价单类交通类型的载流能力;根据区域的主导因素,将区域交通网络问题划分为3类问题域:经济过快型、建设不足型和分流不畅型,并针对性地提出3类网络结构优化方案:中心辐射、均匀分散和中转分流。借鉴双曲线交通结构,对核心问题域(郑洛焦济区)进行优化设计,为交通决策提供信息支持。     

基于数字高程模型的艾比湖湖面近期变化研究

以1：10万地形图为基本数据源,在Golden Soft Surfer等软件支持下建立了艾比湖湖区的数字高程模型。在此基础上,再根据水量平衡方程建立了艾比湖的水量平衡模型和湖面面积变化模型。以艾比湖为实例,从年内与年际多个尺度进行研究,探求湖面面积变化规律及其原因。最后探讨了基于该模型得出的流域生态环境改善措施以及该模型在其他流域的推广。     

单井同位素稀释技术测定西台吉乃尔盐湖水文地质参数

我国含水层的水文地质参数测定,主要依靠传统的抽水试验方法,然而此方法却需要花费大量的试验和钻井费用。同位素示踪方法比传统的抽水试验方法获得含水层参数的周期短、费用低,有效地提高了水文地质参数的测试精度、缩短了工期、节省了投资。为了测定柴达木盆地西台吉乃尔盐湖地下水流速、流向、渗透系数等水文地质参数,采用单井同位素稀释法测试水文地质参数,正确确定其水文地质参数,无论对科学研究还是对生产开采,均有着重要的理论和现实意义。     

基于GIS技术的物流配送线路优化与仿真模拟

以广州市海珠区连锁超市便利店物流配送为例,根据2012年广州市道路网络数据集,结合VRPTW模型（Vehicle Routing Problem with Time Windows）和ArcGIS网络分析模块进行路面顺畅和交通拥堵情况下的配送与仿真模拟。结果表明,在路面顺畅的情况下,3个配送中心只需用到5辆车,花费时间为29 h 10 min,行驶47 834.1 m,即可完成对26个配送点共4 450件货物的配送。而交通拥堵对物流的准时配送产生了显著的影响,随着拥堵时间的增加,整个物流配送过程受到的影响越来越大。在交通拥堵的情况下,选择避开拥堵路段,重新优化配送路线,路线优化后的整个配送过程所行使的总距离比路面通畅时多走了5 182 m,时间上多花了28 min。然而选择优化路线后所花的时间相对于在道路路段拥挤所花费的时间和在每个拥堵路口的等待时间而言,显然优化后的路线更加可取。通过优化路径可以节省费用,节约资源以及减少流通环节中的时间损耗,获得最佳的行驶路线,能有效提高物流配送服务质量和效率。     

基于缓解沙漠高速公路风沙危害的路基参数优化——以榆靖高速公路为例

在沙漠地区修筑高速公路时,风沙对公路路基的危害是公路安全和运营的最大影响因子之一。为了寻求最适合沙漠地区高速公路风沙危害最经济的理论路基断面形式,通过对榆（林）靖（边）沙漠高速公路各种路基实测数据应用数学模型进行定量分析,查明了影响路基沙害程度的主要参数,提出了减少路基沙害程度的设计理念,并对不同路基形式的沙害程度进行了比较,给出了路基沙害程度较小的路基断面形式及参数值。研究成果对今后在沙漠地区修筑高速公路设计及施工具有一定的指导意义。     

不同生态保育尺度下铜陵市土地利用结构优化

与传统发展模式相比,新阶段的土地利用应该与区域自然基础和生态环境格局相匹配,科学判别和保护土地空间增长的生态底线,引导地区土地利用结构的优化具有重要意义。以铜陵市为例,从生态环境约束角度出发,利用土地利用的生态环境敏感性评价方法对区域用地进行分等定级,设定了不同生态保育尺度和不同发展情景下的用地约束界限。在此基础上对铜陵市土地利用结构进行多目标情景分析与优化配置研究,从保障生态环境约束并实现效益最优的角度提出铜陵市土地利用结构优化的方案。