Spatial aggregations for spatial based decision making in spatial data warehouses

For spatial based decision making such as choice of best place to construct a new department store, spatial data warehousing system is required more and more previous spatial data warehousing systems; however, provided decision making of non-spatial data on a map and so those cannot support enough spatial based decision making. The spatial aggregations are proposed for spatial based decision making in spatial data warehouses. The meaning of aggregation operators for applying spatial data was modified and new spatial aggregations were defined. These aggregations can support hierarchical concept of spatial measure. Using these aggregations, the spatial analysis classified by non-spatial data is provided. In case study, how to use these aggregations and how to support spatial based decision making are shown.

A Cautionary Note on the Application of GIS in Spatial Optimization Modeling

Spatial optimization as part of spatial modeling has been facilitated significantly by integration with GIS techniques. However, for certain research topics, applying standard GIS techniques may create problems which require attention. This paper serves as a cautionary note to demonstrate two problems associated with applying GIS in spatial optimization, using a capacitated p-median facility location optimization problem as an example. The first problem involves errors in interpolating spatial variations of travel costs from using kriging, a common set of techniques for raster files. The second problem is inaccuracy in routing performed on a graph directly created from polyline shapefiles, a common vector file type. While revealing these problems, the paper also suggests remedies. Specifically, interpolation errors can be eliminated by using agent-based spatial modeling while the inaccuracy in routing can be improved through altering the graph topology by splitting the long edges of the shapefile. These issues suggest the need for caution in applying GIS in spatial optimization study.

Design and Analysis of Spatial Modulation Based Orthogonal Time Frequency Space System

In this paper,we design a spatial modulation based orthogonal time frequency space(SMOTFS)system to achieve improved transmission reliability and meet the high transmission rate and highspeed demands of future mobile communications,which fully utilizes the characteristics of spatial modulation(SM)and orthogonal time frequency space(OTFS)transmission.The detailed system design and signal processing of the SM-OTFS system have been presented.The closed-form expressions of the average symbol error rate(ASER)and average bit error rate(ABER)of the SM-OTFS system have been derived over the delay-Doppler channel with the help of the union bounding technique and moment-generating function(MGF).Meanwhile,the system complexity has been evaluated.Numerical results verify the correctness of the theoretical ASER and ABER analysis of the SM-OTFS system in the high signal-to-noise ratio(SNR)regions and also show that the SM-OTFS system outperforms the traditional SM based orthogonal frequency division multiplexing(SM-OFDM)system with limited complexity increase under mobile conditions,especially in high mobility scenarios.

Industrial Spatial Agglomeration Using Distance-based Approach in Beijing, China

To study the difference of industrial location among different industries, this article is to test the spatial agglomeration across industries and firm sizes at the city level. Our research bases on a unique plant-level data set of Beijing and employs a distance-based approach, which considers space as continuous. Unlike previous studies, we set two sets of references for service and manufacturing industries respectively to adapt to the investigation in the intra-urban area. Comparing among eight types of industries and different firm sizes, we find that: 1) producer service, high-tech industries and labor-intensive manufacturing industries are more likely to cluster, whereas personal service and capital-intensive industries tend to be randomly dispersed in Beijing; 2) the spillover of the co-location of firms is more important to knowledge-intensive industries and has more significant impact on their allocation than business-oriented services in the intra-urban area; 3) the spatial agglomeration of service industries are driven by larger establishments, whereas manufacturing industries are mixed.

An Effective Image Retrieval Mechanism Using Family-based Spatial Consistency Filtration with Object Region

How to construct an appropriate spatial consistent measurement is the key to improving image retrieval performance. To address this problem, this paper introduces a novel image retrieval mechanism based on the family filtration in object region. First, we supply an object region by selecting a rectangle in a query image such that system returns a ranked list of images that contain the same object, retrieved from the corpus based on 100 images, as a result of the first rank. To further improve retrieval performance, we add an efficient spatial consistency stage, which is named family-based spatial consistency filtration, to re-rank the results returned by the first rank. We elaborate the performance of the retrieval system by some experiments on the dataset selected from the key frames of ＂TREC Video Retrieval Evaluation 2005 （TRECVID2005）＂. The results of experiments show that the retrieval mechanism proposed by us has vast major effect on the retrieval quality. The paper also verifies the stability of the retrieval mechanism by increasing the number of images from 100 to 2000 and realizes generalized retrieval with the object outside the dataset.

Integrating Color and Spatial Feature for Content-Based Image Retrieval

In this paper, we present a novel and efficient scheme for extracting, indexing and retrieving color images. Our motivation was to reduce the space overhead of partition-based approaches taking advantage of the fact that only a relatively low number of distinct values of a particular visual feature is present in most images. To extract color feature and build indices into our image database we take into consideration factors such as human color perception and perceptual range, and the image is partitioned into a set of regions by using a simple classifying scheme. The compact color feature vector and the spatial color histogram, which are extracted from the seqmented image region, are used for representing the color and spatial information in the image. We have also developed the region-based distance measures to compare the similarity of two images. Extensive tests on a large image collection were conducted to demonstrate the effectiveness of the proposed approach.

Parallel scheduling strategy of web-based spatial computing tasks in multi-core environment

In order to improve the concurrent access performance of the web-based spatial computing system in cluster,a parallel scheduling strategy based on the multi-core environment is proposed,which includes two levels of parallel processing mechanisms.One is that it can evenly allocate tasks to each server node in the cluster and the other is that it can implement the load balancing inside a server node.Based on the strategy,a new web-based spatial computing model is designed in this paper,in which,a task response ratio calculation method,a request queue buffer mechanism and a thread scheduling strategy are focused on.Experimental results show that the new model can fully use the multi-core computing advantage of each server node in the concurrent access environment and improve the average hits per second,average I/O Hits,CPU utilization and throughput.Using speed-up ratio to analyze the traditional model and the new one,the result shows that the new model has the best performance.The performance of the multi-core server nodes in the cluster is optimized;the resource utilization and the parallel processing capabilities are enhanced.The more CPU cores you have,the higher parallel processing capabilities will be obtained.

Spatial-temporal Pattern Evolution of Manufacturing Geographical Agglomeration and Influencing Factors of Old Industrial Base:A Case of Jilin Province,China

The primary object of this paper is to examine the spatial-temporal pattern evolution of manufacturing geographical agglomeration of the old industrial base.Industrial spatial agglomeration index and concentration ratio are used in this paper.Multiple linear regression models are also applied to try to explore the internal driving mechanisms on manufacturing geographical agglomeration.The results show that:1) the manufacturing agglomeration degree of Jilin Province is increasing gradually.The spatial polarization structure is visible;and the central region is the agglomeration area,in addition,the manufacturing industries of Changchun Proper present a trend of dispersion;2) the structure of manufacturing industries has changed,and the concentration ratio of labor-intensive manufacturing industry is declining,while the proportions of technology-intensive and capital-intensive manufacturing industry are relatively rising;3) marketing level,location accessibility,labor resources,capital,science and technology innovation capability,scale economy and the level of globalization affect manufacturing agglomeration with different degree.There are significant differences of the effects about employment,technology,the quality of residents and the export-oriented market on the industrial concentration ratio;4) in the future,the impact of policy and institution,export-oriented market and quality of resident on manufacturing geographical agglomeration pattern will be more profound.

Low insertion loss silicon-based spatial light modulator with high reflective materials outside Fabry–Perot cavity

The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth: their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.

The Closed-form Solution of Groebner Bases for the Spatial Burmester Problem

Groebner bases is an important concept in polynomial ideals. In this paper the method of Groebner bases is applied to solving spatial Burmester problem for the first time, and the symbolic “triangular” Groebner bases, i.e. the closed form solution for the problem is obtained. An example of the synthesis of rigid body guidance of a spatial 5 s s mechanism which can realize spatial Burmester points is given to demonstrate the efficiency of the method.

基于混合优化算法的电磁监测裂缝参数识别

压裂实时监测是水力压裂效果评价和工程参数优化的重要保障措施之一。传统电磁监测裂缝参数识别方法的准确性和精度难以保证,影响了监测效果。为了提高裂缝参数识别能力,提出了一种基于海洋捕食者密度聚类混合优化算法的电磁监测裂缝参数识别方法。利用海洋捕食者算法(MPA)进行多次寻优,以每次寻优结果作为初始数据集,然后,利用密度聚类算法(DBSCAN)进行聚类,构建中间样本数据集,最后,抽取该样本数据中值作为最终输出结果。采用Rastrigin函数进行测试,分析混合优化算法寻优能力。测试结果表明,相对粒子群优化算法(PSO),MPA算法单次寻优效果较佳。但两种算法寻优结果均具有较强随机性,其中,PSO和MPA算法50次寻优精度分别为10^(-7)~10^(2)和10^(-10)~10^(-2),而改进的混合优化算法寻优效果更稳定,寻优精度达10^(-7)。构建缝长、方位压裂模型并进行了数值模拟实验,结果表明,在噪声低于15%时,缝长和方位识别平均绝对误差分别小于1 m和1°。利用改进的算法对四川盆地某井页岩气压裂电磁监测实测数据进行分析,确定了裂缝改造的长度(缝长)与方位。实例分析结果验证了改进算法的可行性和有效性。

空间目标天基光学定位方法综述

近年来空间目标定位领域不断结合网络协同、多模融合等探测技术,发展迅速。其中,基于天基光学探测的定位方法以隐蔽性好、测量精度高的独特优势在民用和国防领域应用广泛。为了分析不同情景下适用于不同类型目标的定位方法,针对基于天基光学探测的空间小目标定位进行综述。首先介绍天基光学探测技术的发展、空间目标的分类和特点以及空间目标定位的概念。然后着重分析适用于空间“小、弱”目标的单星和多星定位方法,并对近年提出的异质传感器联合定位展开说明。最后,依据成像过程建立空间目标定位误差分析模型,分析定位精度的影响因素占比并根据现存问题做出总结和展望。

江西省森林康养基地空间分布与影响因素

江西省森林资源丰富,为森林康养产业发展提供了得天独厚的基础条件。森林康养基地是开发森林康养产业的基础支撑,系统研究江西省森林康养基地空间分布格局及影响因素,对森林康养产业高质量发展具有重要意义。依托136处江西省森林康养基地点位数据,运用GIS空间分析法及地理探测器探究森林康养基地空间分布及影响因素。结果表明:江西省森林康养基地整体呈现“东西聚集,北密南疏”的不均衡空间分布格局,具有多核心且沿市界边缘布局的特征。江西省森林康养基地空间分布由自然资源因素和社会经济因素共同作用而成,受自然资源因素影响,空间分布表现出“近低地、沿缓坡、亲水域、依附旅游区”的特点,自然优势条件分别为海拔200 m以下、地形起伏度0 m~50 m、坡度5°~15°、距水系5 km以内;在社会经济因素中,公路通车里程数、地方财政农林水支出、农林牧渔业生产总值对森林康养基地空间分布影响程度较大,而城镇居民人均可支配收入和人均生产总值的解释力较弱,并与森林康养基地密度呈现负相关。

考虑土性参数空间变异性的珠三角软土地区土钉支护结构可靠度分析

如何定量定性描述软土土性参数空间变异性对准确确定软土土性参数和合理评价软土地区土钉支护结构稳定性至关重要。采用既有统计分析方法定量描述空间变异性通常需要大量数据,难以满足。本文基于随机场理论模拟软土土性参数空间变异性,建立了一套考虑土性空间变异性的软土地区土钉支护结构可靠度设计方法,最后以MATLAB软件包为平台进行计算程序的开发与工程实例研究。分析结果表明,本文采用随机场方法模拟软土土体固有空间变异性及其在土钉支护结构可靠度分析中的应用具有合理性与普适性。

基于改进DBSCAN的船舶会遇识别模型

为解决大数据下船舶会遇识别算法效率不高且存在误判等问题,提出一种融合国际海上避碰规则(International Regulations for Preventing Collisions at Sea,COLREGs)的带噪声的基于密度的空间聚类(density-based spatial clustering of applications with noise,DBSCAN)算法,建立船舶会遇识别模型。在DBSCAN算法对邻域内的船舶数量进行统计时,计算船舶间的最近会遇距离(distance to closest point of approach,DCPA)和最近会遇时间(time to closest point of approach,TCPA),初步筛选邻域内的噪声点;基于模糊综合评价模型计算船舶会遇风险,对邻域内的船舶进行二次筛选,实现船舶会遇态势的提取。结果表明:改进后的DBSCAN算法过滤掉传统DBSCAN算法识别到的非会遇局面,并且在同一会遇局面下的船舶数量均保持在4艘以内;输出的会遇船舶风险演变趋势对实际水域内高风险船舶的监控适用性较好,能有效辅助船舶避碰。所提识别模型对保障航行安全和提高海事监管效率具有重要意义。

基于时空关联的车联网假位置筛选算法

目前,车联网位置隐私保护方法没有充分考虑到不同的时间段内假位置查询概率的变化,同时忽视了对于连续时间背景下同一位置单元每天的用户访问量变化趋势有较大差异的问题。针对上述缺陷,提出空间敏感度度量标准,在选择假位置时综合考虑位置语义相似度提出语义-空间敏感度期望的筛选指标,生成满足分时间段查询概率、匿名区域面积要求的假位置集合。实验结果证明了新算法的可行性及有效性,能够适应当下的车联网位置隐私保护需求。

结合载客热点和POI的出租车停车位划定方法

针对出租车随意停靠造成城市交通拥堵甚至交通事故的问题,利用成都实际区域的出租车GPS(Global Position System)数据和爬取的POI(Point of Interest)数据,使用DBSCAN(Density-Based Spatial Clustering of Application with Noise)聚类算法对上下客点进行聚类,得到出租车的载客热点,根据POI的类型划定载客热点区域的类型,对出租车不同时间的出行需求进行分析,进而划分出出租车的固定停车区域。研究结果表明,出租车固定停车区域的设定与出行者的出行需求有关,即将固定停车区域设置在出行者出行需求多的区域,可以满足出行者的不同出行需求。结合出租车载客热点和爬取POI数据划定固定停车区域的方法具有较高的实用性,可为城市交通安全方面提供理论和现实意义。

磁共振弥散张量成像评估针刺治疗儿童孤独症的疗效价值研究

目的 采用磁共振弥散张量成像(diffusion tensor imaging, DTI)观察针刺治疗前后孤独症谱系障碍(autism spectrum disorder, ASD)患儿脑白质微观结构的变化,以探索针刺在ASD中应用价值及DTI在评估针刺效果中作用。材料与方法 前瞻性纳入2021年11月至2022年10月在我院确诊的ASD患儿,按照随机数字表法分为针刺组和假针刺组,进行12周的干预治疗,于治疗前(第0周)及治疗后(第12周)行儿童孤独症评定量表(Child Autism Rating Scale, CARS)、孤独症儿童行为量表(Autism Behavior Checklist, ABC)、孤独症疗效评价量表(Autism Treatment Evaluation Checklist, ATEC)及DTI检查。比较两组间各项量表评分变化,采用基于纤维束示踪的空间统计方法(tract-based spatial statistics, TBSS)分析两组间脑白质各向异性分数(fractional anisotropy, FA)的差异,继而比较FA有差异脑区的平均弥散率(mean diffusivity, MD)、径向弥散系数(radial diffusivity, RD)和轴向弥散系数(axial diffusivity, AD)的不同及量表评分与DTI参数相关性。结果 与假针刺组相比,治疗后针刺组各项量表评分较治疗前显著降低,差异具有统计学意义(P<0.05)。治疗后两组间FA值差异具有统计学意义(P<0.05),RD值差异无统计学意义(P>0.05),AD值两组间在左下纵束差异有统计学意义(P<0.05)。相关性分析发现:ASD患儿ATEC评分与右扣带回的FA值呈负相关,与右额枕下束、右下纵束、右扣带回的RD值呈正相关,与右扣带回的AD值呈正相关;CARS评分与右扣带回的AD值呈正相关(P<0.05)。右下纵束的FA值与ASD患儿的语言问题、感知觉异常呈负相关,RD值与社交障碍、感知觉异常呈正相关;右扣带回的FA值与语言问题、社交障碍、感知觉异常呈负相关,而RD值与上述临床症状呈正相关,AD值与社交障碍、健康问题呈正相关;双侧额枕下束FA值与感知觉异常存在负相关,右额枕下束RD值与其社交障碍、感知觉异常呈正相关;右上纵束的RD值与感知觉异常呈正相关;左丘脑前辐射束的AD值与感知觉异常呈正相关(P<0.05)。结论 针刺可能通过促进脑白质纤维束完整性增强,从而改善ASD患儿临床症状,尤其在言语、社交、感知觉、健康问题等方面,进而说明DTI在评估针刺治疗效果中具有重要价值。

塔里木盆地及其周边地区大气可降水量分布及其与降水关系的研究

利用2018年7月至2022年6月塔里木盆地及其周边地区17部地基GPS水汽探测仪遥感的大气可降水量(PWV)资料、 14个地面气象站逐时和逐日降水资料,分析了塔里木盆地西部(区域A)和东部(区域B)PWV分布特征及其与降水关系。结果表明:(1)研究区年平均PWV高值区主要集中于盆地北部和盆地西南部平原地区,海拔超过1300 m站点的PWV年平均值与海拔成反比,低于1300 m的低海拔地区PWV年平均值在10~12 mm。夏季测站PWV平均值是春、秋季节的2倍。(2)区域A和区域B PWV月变化呈单峰型分布,分别在8月和7月达到峰值。区域A有、无降水日PWV均在23:00(北京时,下同)达到日峰值。区域B有、无降水日PWV日峰值出现时间相差5 h,分别出现在11:00和17:00。(3)区域A和区域B多数测站ΔPWV(PWV与PWV月平均值差值)峰值分别在降水开始前0~1 h和降水开始时刻前后1 h出现。春季区域B降水前PWV跃变程度较区域A更剧烈,夏季各区域σPWV(PWV与PWV月平均值倍数)提前降水开始时刻1 h、 5~6 h达到1~1.8倍的天气过程较其余时次偏多。秋季和冬季区域BσPWV分别集中在1.4~2.0倍和1.6~2.4倍。(4)海拔高于1400 m测站的5-6月、 7-8月PWV值达到10~20 mm和15~25 mm,对应降水结束时刻。海拔低于1400 m测站5-8月降水结束时刻PWV值逐渐由15~25 mm增至25~35 mm。

Spatial Organisation Influences Citrus <i>Pseudocercospora</i>Leaf and Fruit Spot Disease Severity in Cocoa-Based Agroforestry Systems

An investigation to assess the spatial structure and severity of Pseudocercospora leaf and fruit spot disease (PLFSD) on citrus trees in cocoa-based agroforests was carried out in three contrasting ecological zones in southern Cameroon, viz: 1) the humid forest zone, 2) the degraded forest zone, and 3) the forest-savannah transition zone. Two main parameters were investigated viz: 1) the spatial structure of cocoa based agroforests, and 2) the disease severity. In total, the spatial structure of 19 cocoa-based agroforests was analysed using the Ripley K(r) function, meanwhile the collection of epidemiological data that consisted of noting the presence of PLFSD spots on leaves and fruits on 438 citrus trees was used to characterise the severity of the disease. Results showed that, the spatial structure of citrus trees in these agroforests investigated were regular in seven plots, random in nine, and aggregated in three. Aggregated plots presented a significantly higher mean of disease severity on leaves and fruits (28.55 and 30.37 respectively), as compared to randomised (20.91 and 16.32 respectively) and regular plots (16.28 and 14.97 respectively), at P-value < 0.05. These results suggest that the spatial structure of citrus trees in the cocoa-based agroforests studied influences the severity of PFLSD. Proper integrated control measures can therefore be initiated, leading to a considerable reduction of the use of manufactured inputs, and thereby, the cost of production of citrus fruits.