“雨燕”中风暴算法在北京奥运天气预报示范项目中的应用及改进

介绍了临近预报系统“雨燕”中的风暴系列算法, 包括风暴识别、 风暴追踪、 基于TREC技术的风暴位置预报, 以及预报位置实时评分算法等。利用2008年北京奥运期间出现的多个强对流天气, 统计出该风暴产品在30 min和60 min预报时效的绝对距离误差分别约为13 km和23 km。分析了北京奥运天气预报示范项目期间该风暴产品误差较大的原因, 主要集中于TREC技术本身及其适用范围, 以及风暴预报方案中处理细节的不足, 具体为TREC技术不适用于孤立的回波单体, 雷达探测边界对TREC技术的影响, TREC矢量有时呈现出一定的空间不连续性, 以及对孤立少动单体的不当处理等。针对上述原因, 提出了一系列的改进方案, 包括对用于风暴位置预报的TREC矢量增加一致性检验, 利用风暴的历史轨迹校正不恰当的TREC矢量; 对TREC技术中象素阵列大小进行统计分析, 选择最适合北京地区的阵列大小; 风暴预报位置超出回波范围时新的处理技巧等。利用北京奥运期间的强对流资料, 对改进后的风暴算法进行评估。结果表明, 一方面, 改进后的算法能较好地控制风暴预报位置的绝对误差, 在30 min和60 min预报时效, 绝对误差分别减小了25%和26%。另一方面, 由于预报位置精度的提高, 能够提升相邻时刻风暴匹配的效率, 使得与以前算法相比有更多的风暴样本参与了各个预报时效的评分。     

Comparison of genetic algorithms and shuffled complex evolution approach for calibrating distributed rainfall–runoff model

Three methods, Shuffled Complex Evolution (SCE), Simple Genetic Algorithm (SGA) and Micro‐Genetic Algorithm (µGA), are applied in parameter calibration of a grid‐based distributed rainfall–runoff model (GBDM) and compared by their performances. Ten and four historical storm events in the Yan‐Shui Creek catchment, Taiwan, provide the database for model calibration and verification, respectively. The study reveals that the SCE, SGA and µGA have close calibration results, and none of them are superior with respect to all the performance measures, i.e. the errors of time to peak, peak discharge and the total runoff volume, etc. The performances of the GBDM for the verification events are slightly worse than those in the calibration events, but still quite satisfactory. Among the three methods, the SCE seems to be more robust than the other two approaches because of the smallest influence of different initial random number seeds on calibrated model parameters, and has the best performance of verification with a relatively small number of calibration events. Copyright © 2009 John Wiley & Sons, Ltd.     

利用重测定的震源深度特征探讨2013年吉林前郭5.8级震群发震因素

利用Pn-Pg震相组合的局部搜索法,采用5种地壳速度模型对2013年吉林前郭5.8级地震震群进行震源深度测定。计算结果显示,5种结果的震源深度的主要分布特征相似。对选取的32个地震震源深度进行重新测定,结果最小为6 km,最大14 km,主要集中在10 km左右,系统深度偏差约1.74 km,震源深度分辨率约1.58km,重定位后地震震中优势分布呈北西向。与当地的沉积层厚度分布对比,这些地震最有可能发生在盆地基底的基岩顶层,而不在油气圈闭的沉积盖层内,并且地震震群分布走向与通榆—长春断裂走向相一致。结合该地区的历史地震活动与构造关系,最后推测这些地震与北西向的通榆—长春断裂构造运动密切相关,而不是油田作业的直接产物。     

Finding shortest paths on real road networks: the case for A*

The problem of identifying the shortest path along a road network is a fundamental problem in network analysis, ranging from route guidance in a navigation system to solving spatial allocation problems. Since this type of problem is solved so frequently, it is important to craft an approach that is as efficient as possible. Based upon past research, it is generally accepted that several efficient implementations of the Dijkstra algorithm are the fastest at optimally solving the ‘one‐to‐one’ shortest path problem (Cherkassky et al. 1996 Cherkassky, B. V., Goldberg, A. V. and Radzik, T. 1996. Shortest paths algorithms: theory and experimental evaluation.. Mathematical Programming: Series A and B, 73: 129–174. [Crossref], [Web of Science ®] , [Google Scholar]). We show that the most efficient state‐of‐the‐art implementations of Dijkstra can be improved by taking advantage of network properties associated with GIS‐sourced data. The results of this paper, derived from tests of different algorithmic approaches on real road networks, will be extremely valuable for application developers and researchers in the GIS community.     

A spatial genetic algorithm for automating land partitioning

Land fragmentation is a widespread situation which may often hinder agricultural development. Land consolidation is considered to be the most effective land management planning approach for controlling land fragmentation and hence improving agricultural efficiency. Land partitioning is a basic process of land consolidation that involves the subdivision of land into smaller sub-spaces subject to a number of constraints. This paper explains the development of a module called LandParcelS (Land Parcelling System) that is a part of an integrated planning and decision support system called LACONISS (LAndCONsolidation Integrated Support System) which has been developed to assist land consolidation planning in Cyprus. LandParcelS automates the land partitioning process by designing and optimising land parcels in terms of their shape, size and value. The methodology integrates geographical information systems and a genetic algorithm that has been applied to two land blocks that are part of a larger case study area in Cyprus. Partitioning is treated as either a single or multi-objective problem for various optimisation cases. The results suggest that a step forward has been made in solving this complex spatial problem, although further research is needed to improve the algorithm. This approach may have relevance to other spatial planning tasks that involve single or multi-objective optimisation problems, especially those dealing with space partitioning.     

Jacques Bertin’s legacy in information visualization and the reorderable matrix

ABSTRACT

Jacques Bertin’s legacy extends beyond the domain of cartography, and in particular to the field of information visualization where he continues to inspire researchers and practitioners. Although in the late twentieth century his books were out of print, their reedition around 2010 has steered a renewed interest and inspired new generations of researchers to reinterpret the principles of Semiology of Graphics and La Graphique in a time of interactive computers. In particular, the work of Jacques Bertin on the reorderable matrix has been very challenging in his time, and the quest to its automation has not been satisfactory to him. This article summarizes Bertin’s approach to the reorderable matrix, underlines the limitations of fully automated reordering methods, and introduces Bertifier, a hybrid system to reorder matrices using a combination of machine assistance and human control.     

锥形束重构解析算法的研究历程及内在联系

本文提出了锥形束重构解析算法研究历程中的主要问题,阐述了锥形束重构领域相关数学理论和数值计算方法建立与发展的脉络,剖析了锥形束重构研究过程中各算法的内在联系。指出了该领域今后研究工作的某些关键问题。     

CAPPS多箱模式中光化学模式的嵌套与城市大气臭氧数值预报

为解决城市边界层中大气O3浓度的预报问题,选用一种简明有效的光化学反应方案建立光化学模式, 并与大气平流扩散的箱格预报模型进行了嵌套,从而将大气化学过程引入到城市空气污染数值预报系统 (CAPPS) 中。同时,根据实际需要研究了VOC (Volatile Organic Compounds) 浓度及NOx源排放量等参数缺测时,根据前期监测浓度采用遗传算法反演未知参数的具体方法。利用2001年9月8~17日在北京舞蹈学院监测的O3、NOx资料及相应的气象数据,用改进后的CAPPS模式进行了单箱预报试验。预报试验结果表明,嵌套后的模式对O3浓度的变化具备一定的预报能力。     

Derivation of a resilient polygon centroid for natural resource management applications

This paper reviews the utility of polygon centroid algorithms for natural resource management applications. Following a review of ‘standard’ centroid derivation algorithms, and their limitations, alternative approaches are proposed. Building upon current polygon-reduction algorithms an iterative edge-erosion model is presented. Resilient centroids derived via this model are shown to: (1) maximise the distance to all internal and external edges; (2) be located within the polygon boundary; and (3) be insensitive to patch vertex outliers.

The resilient centroid is demonstrated to have utility in a range of natural resource management applications including the matching of disparate data sources. Exemplar studies conclude that resilient centroids support an appropriate allocation of vegetation condition point samples both within and between native vegetation patches. Further, the utilisation of resilient centroids enables the (1) sub-division of vegetation patches into homogenous regions (core areas) and (2) interrogation of the relationship between vegetation condition and core area proximity.     

Multi‐objective optimal design of FLC driven hybrid mass damper for seismically excited structures

Structural vibration control using active or passive control strategy is a viable technology for enhancing structural functionality and safety against natural hazards such as strong earthquakes and high wind gusts. Both the active and passive control systems have their limitations. The passive control system has limited capability to control the structural response whereas the active control system depends on external power. The power requirement for active control of civil engineering structures is usually quite high. Thus, a hybrid control system is a viable solution to alleviate some of the limitations. In this paper a multi‐objective optimal design of a hybrid control system for seismically excited building structures has been proposed. A tuned mass damper (TMD) and an active mass driver (AMD) have been used as the passive and active control components of the hybrid control system, respectively. A fuzzy logic controller (FLC) has been used to drive the AMD as the FLC has inherent robustness and ability to handle the non‐linearities and uncertainties. The genetic algorithm has been used for the optimization of the control system. Peak acceleration and displacement responses non‐dimensionalized with respect to the uncontrolled peak acceleration and displacement responses, respectively, have been used as the two objectives of the multi‐objective optimization problem. The proposed design approach for an optimum hybrid mass damper (HMD) system, driven by FLC has been demonstrated with the help of a numerical example. It is shown that the optimum values of the design parameters of the hybrid control system can be determined without specifying the modes to be controlled. The proposed FLC driven HMD has been found to be very effective for vibration control of seismically excited buildings in comparison with the available results for the same example structure but with a different optimal absorber. Copyright © 2002 John Wiley & Sons, Ltd.