Fragment spatial distribution of prismatic casing under internal explosive loading

Non-cylindrical casings filled with explosives have undergone rapid development in warhead design and explosion control.The fragment spatial distribution of prismatic casings is more complex than that of traditional cylindrical casings.In this study,numerical and experimental investigations into the fragment spatial distribution of a prismatic casing were conducted.A new numerical method,which adds the Lagrangian marker points to the Eulerian grid,was proposed to track the multi-material interfaces and material dynamic fractures.Physical quantity mappings between the Lagrangian marker points and Eulerian grid were achieved by their topological relationship.Thereafter,the fragment spatial distributions of the prismatic casing with different fragment sizes,fragment shapes,and casing geometries were obtained using the numerical method.Moreover,fragment spatial distribution experiments were conducted on the prismatic casing with different fragment sizes and shapes,and the experimental data were compared with the numerical results.The effects of the fragment and casing geometry on the fragment spatial distributions were determined by analyzing the numerical results and experimental data.Finally,a formula including the casing geometry parameters was fitted to predict the fragment spatial distribution of the prismatic casing under internal explosive loading.

权力、资本的碎化与尺度修复:城镇开发边界的政治经济学解释

文章从权力、资本与空间互动的视角审视中国城市增长主义下的空间增长逻辑,为城镇开发边界划定提供理论认知与实践建议。研究发现:(1)央地间的用途管制冲突、市辖区间的经济发展机会争夺造成规划增量空间大规模碎片状分散;(2)资本再地域化的空间需求与城镇开发边界的空间供给错配,资本避险引发空间治理危机;(3)城镇开发边界通过尺度上移、尺度外移的方式实现资本积累的尺度修复。文章从政治经济学视角理解城市空间增长内在逻辑与城镇开发边界的内涵,对城镇开发边界的划定具有重要理论与实践价值。

基于景观指数的关中地区耕地细碎化程度的时空变迁及其驱动因素

[目的]优化陕西耕地细碎化治理,协调粮食需求增长与环境约束之间的矛盾,维护地区粮食安全和促进农业现代化发展。[方法]以关中地区为研究区,以土地利用数据和其他自然经济数据为基础,运用洛伦兹曲线、变异系数法、景观指数、空间自相关等方法构建耕地细碎化评价模型以探索关中地区耕地细碎化(Cultivated Land Fragmentation,简称CLF)的时空变迁,并利用地理探测器对区内CLF进行了驱动力分析。[结果](1)关中地区耕地资源空间分布相对均衡,耕地专业化程度保持较高水平。(2)关中地区的CLF程度变化时空差异显著,CLF程度整体呈现下降态势,但部分地区CLF程度呈增减并存趋势,整体呈现东低西高的态势。(3)关中地区CLF时空分化受多种因素影响,社会经济因素的综合影响明显强于自然因素,其中海拔高度、人口密度、人均耕地面积和地区总产值GDP为主要影响因素;因子间的交互作用效应强于单因子,以双因子增强和非线性增强为主。[结论]关中地区耕地细碎化问题在20年间得到了一定程度的改善,但呈现出较大的地区差异,应进一步在社会经济因素方面对耕地细碎化现象加强综合治理,以推动关中地区农业机械化、现代化发展。

鄱阳湖生态经济区建设用地扩张对耕地景观破碎化的影响

为分析鄱阳湖生态经济区耕地景观与建设用地扩张之间的关系,利用形态学空间格局分析法研究2000-2020年耕地景观破碎化的形态学特点,同时运用外溢效应分析、景观格局指数分析、地理加权回归等模型方法,探究建设用地扩张对耕地景观破碎化的影响。结果表明:2000-2020年间耕地景观破碎化程度加强,核心区面积减少强度由1.33%提高到6.27%,并表现出由平原地区向山地丘陵区加强的地域性差异,且建设用地扩张会导致耕地景观破碎化;建设用地占用耕地的面积由268.60 km2增加到1 003.26 km2,主要发生在路网成熟的地区;建设用地扩张对耕地的外溢效应逐渐增强,在路网成熟地区更显著;建设用地扩张对耕地景观破碎化有较强的正向影响,道路建设对这种影响有强化作用,同时,耕地景观破碎化表现出随道路缓冲距离的减小而加强的阶梯性差异。研究表明,耕地景观破碎化程度受地形和建设用地扩张的影响显著,耕地景观破碎化现象主要发生在地势起伏大或建设用地密集、路网成熟的地区。

规划管控约束下耕地细碎化评价与整治分区

科学评估耕地细碎化治理的适宜性与必要性,并进行合理的整治分区有利于耕地资源的高效利用与空间布局,促进三生空间协调发展。该研究以典型山区县及资源型城市江西省德兴市为例,基于村域尺度,从生产适宜性、空间集聚性、管控约束性3个视角构建评价体系,采用多因素综合叠加评价法对耕地细碎化进行评价,借助三维魔方空间分类法开展整治分区研究。结果表明:1)各村耕地资源生产适宜性良好,均值为0.558;空间集聚性一般,均值为0.350;管控约束性标准差大于均值,各村差异较大;耕地细碎化治理适宜性较高,均值为0.711。2)统筹评价结果将德兴市划分为高质保障区、综合整治区、设施优化区、集约整合区以及现状维持区5区,基于各区生产适宜性、空间集聚性与管控约束性差异制定差别化整治措施与治理策略。研究结果可为耕地细碎化整治提供有益的参考借鉴。

缓冲区分析和空间叠加分析下的智慧石油管网时序标准化片段巡检技术

传统的智慧石油管网时序标准化片段巡检技术仅对采集的数据进行降噪处理,巡检效果不佳。设计了缓冲区分析和空间叠加分析下的智慧石油管网时序标准化片段巡检技术。利用红外图像采集设备,对石油管网运行过程中的数据进行采集,并对采集的数据进行灰度化、对比度增强和降噪处理。利用空间叠加分析的特性,将预处理的图像数据进行叠加,通过计算提取叠加后的图像数据特征,在缓冲区分析的作用下设定巡检路径规划三维空间,通过计算巡检点到虚拟直线之间的距离构建相应的巡检路径规划模型,通过对规划的巡检路径进行评价,判断当前路径是否符合要求,从而完成对石油管网时序标准化片段的巡检。仿真实验表明,缓冲区分析和空间叠加分析下的智慧石油管网时序标准化片段巡检技术的巡检安全性指标为0.954,与传统的智慧石油管网时序标准化片段巡检技术相比巡检效果更好,可靠性更强。

Quantification of projection angle in fragment generator warhead

Tactical Ballistic Missile(TBM) class target neutralization by the fragment spray of a Fragment Generator Warhead(FGW) calls for quantification of fragment projection angle scatter to finalize the end game engagement logic.For conventional axi-symmetric warhead,dispersion is assumed to be normal with a standard deviation of 3~O.However,such information is not available in case of FGW.Hence,a set of experiments are conducted to determine the dispersion of fragments.The experiments are conducted with a specific configuration of FGW in an identical arena to quantify the scatter and then verified its applicability to other configurations having a range of L/D and C/M ratios,and contoured fragmenting discs.From the experimental study,it is concluded that the scatter in projection angle follows normal distribution with a standard deviation of 0.75° at Chi-square significance level of 0.01(x_(0.99)~2).

Characterisation of Landscape with ForestFragmentation Dynamics

Land cover (LC) and land use (LU) dynamics induced by human and natural processes play a major role in global as well as regional patterns of landscapes influencing biodiversity, hydrology, ecology and climate. Changes in LC features resulting in forest fragmentations have posed direct threats to biodiversity, endangering the sustainability of ecological goods and services. Habitat fragmentation is of added concern as the residual spatial patterns mitigate or exacerbate edge effects. LU dynamics are obtained by classifying temporal remotely sensed satellite imagery of different spatial and spectral resolutions. This paper reviews five different image classification algorithms using spatio-temporal data of a temperate watershed in Himachal Pradesh, India. Gaussian Maximum Likelihood classifier was found to be apt for analysing spatial pattern at regional scale based on accuracy assessment through error matrix and ROC (receiver operating characteristic) curves. The LU information thus derived was then used to assess spatial changes from temporal data using principal component analysis and correspondence analysis based image differencing. The forest area dynamics was further studied by analysing the different types of fragmentation through forest fragmentation models. The computed forest fragmentation and landscape metrics show a decline of interior intact forests with a substantial increase in patch forest during 1972-2007.

Design of a spatial sampling scheme considering the spatial autocorrelation of crop acreage included in the sampling units

Information on crop acreage is important for formulating national food polices and economic planning. Spatial sampling, a combination of traditional sampling methods and remote sensing and geographic information system （GIS） technology, provides an efficient way to estimate crop acreage at the regional scale. Traditional sampling methods require that the sampling units should be independent of each other, but in practice there is often spatial autocorrelation among crop acreage contained in the sampling units. In this study, using Dehui County in Jilin Province, China, as the study area, we used a thematic crop map derived from Systeme Probatoire d＇Observation de la Terre （SPOT-5） imagery, cultivated land plots and digital elevation model data to explore the spatial autocorrelation characteristics among maize and rice acreage included in sampling units of different sizes, and analyzed the effects of different stratification criteria on the level of spatial autocorrelation of the two crop acreages within the sampling units. Moran＇s/, a global spatial autocorrelation index, was used to evaluate the spatial autocorrelation among the two crop acreages in this study. The results showed that although the spatial autocorrelation level among maize and rice acreages within the sampling units generally decreased with increasing sampling unit size, there was still a significant spatial autocorrelation among the two crop acreages included in the sampling units （Moran＇s / varied from 0.49 to 0.89）, irrespective of the sampling unit size. When the sampling unit size was less than 3000 m, the stratification design that used crop planting intensity （CPI） as the stratification criterion, with a stratum number of 5 and a stratum interval of 20% decreased the spatial autocorrelation level to almost zero for the maize and rice area included in sampling units within each stratum. Therefore, the traditional sampling methods can be used to estimate the two crop acreages. Compared with CPI, there was still a strong spatial correlation among the two crop acreages included in the sampling units belonging to each stratum when cultivated land fragmentation and ground slope were used as stratification criterion. As far as the selection of stratification criteria and sampling unit size is concerned, this study provides a basis for formulating a reasonable spatial sampling scheme to estimate crop acreage.

Spatial Structure Adjustment Strategies of the Coal Resource-Based Cities during the Mature Period: A Case Study of Pingdingshan

Coal cities are the main part of the resource-based cities in China, and the benign development of coal cities' spatial structure has a direct impact on these cities' future economic and social development, as well as the urban residents' welfare. Land use fragmentation is the most typical morphological characteristic of the coal city's spatial structure development. In this paper, Pingdingshan City of Henan Province in China is taken as an example. Through empirical analysis, the urban spatial structure development processes of a typical coal resource-based city in its mature period are illustrated, and the formation reasons and potential mechanism behind coal city land use fragmentation are explored, and the measurement method of land use fragmentation degree of the coal city is put forward. On the above basis, the appropriate adjustment strategies and methods aimed at the coal city spatial structure are found out and given. This study is a good guideline and reference for the spatial structure planning and land use planning of the coal city during the mature and declining period, which is of great help to the sustainable development and industrial structure transformation of the coal city. It also has certain reference significance for the coal city in the growth period.

盐城市景观格局演变特征及驱动因素研究

探讨沿海城市土地利用时空变化对景观格局的影响,对于深化和揭示土地利用对景观功能的效应有重要意义。根据1990、2000、2010、2020年沿海城市盐城4期Landsat遥感影像,通过ENVI5.2监督分类及目视解译,得到4期土地利用分类数据,运用土地利用动态度、马尔科夫转移矩阵来分析土地类型的变化差异性,从而揭示盐城市景观格局的演变特征。结果表明,1990-2020年盐城市耕地面积减少了近400 km^(2),部分耕地转变为草地和水体,水体占比从2.26%增加至9.35%,呈现快速增长趋势,耕地和林地呈快速减少趋势,建设用地转入转出频繁,但总体转化增速较为缓慢。研究时段后期,滩涂滩地占比从4.05%降低至2.29%,逐渐向草地和水体转化。1990-2020年盐城市土地利用变化剧烈导致景观格局指数发生显著变化,耕地的斑块数量和斑块密度逐年增加,说明耕地破碎化程度呈现逐渐增强的趋势。研究区内各用地类型边缘密度增加,蔓延度指数、聚合度指数减少,说明研究区域内的景观边缘形状指数趋于复杂,景观类型的离散度增加,区域空间范围内的聚集性减弱。各种景观类型变化差异相对增大,使得近30 a盐城市的景观格局趋于复杂,滩涂滩地的特殊性质更是加剧了不同景观间的异质性。以上分析表明,人为干预、社会经济以及城市建设发展成为影响盐城市景观格局变化的主要因素。

丘陵区耕地细碎化与种植多样性的空间相关性分析——以武胜县鸣钟乡为例

利用2019年分辨率为20 m的航拍影像矢量数据,获得武胜县鸣钟乡19个村的耕地细碎化景观指数,运用主成分降维分析方法,获取能够代表耕地细碎化的3个主成分(F_(1)、F_(2)、F_(3))指标,对鸣钟乡耕地细碎化与农户种植多样性的空间自相关规律进行了分析。结果表明:(1)主成分F_(1)、F_(2)、F_(3)累计方差贡献率大于90%,能够表达10个原始景观指数的大部分信息,代表耕地细碎化程度;(2)耕地细碎化Moran’s散点图显示,19个离散点中有12个离散点落入第一象限和第三象限,表明这些范围内的耕地细碎化程度与农作物种植多样性具有较强的空间正相关,局部集聚显著;(3)F_(1)、F_(2)、F_(3)与农户种植多样性空间聚集度指数显示,高值聚集区由中华村、响水滩村和龙庙村组成,低值聚集区由大锣山村、大石村和高升村组成。由此可见,耕地细碎化与农户种植多样性呈现空间正相关性,空间耦合度较好。

Research on Analysis of Landscape Spatial Characteristic of Urban Green Land in Wuhua District of Kunming City in China

With the help of 1∶20 000 satellite image of Kunming City and its satellite remote sensing image with resolution ratio 10 m, based on statistic data from Greening Department of Wuhua District and data collected through field study, by making use of landscape ecological theory and methods, the paper had selected three indexes reflecting landscape spatial characteristic including average patch area, landscape fragmentation and landscape connectivity, to analyze landscape spatial characteristic of urban green land. And then it obtained that urban green land of Wuhua District was dominated by small patches, and patches' average area was small; urban green patches were small and fragmented, and landscape fragmentation was high; landscape connectivity was weak and ecological corridor was narrow, failing to bring ecological effect of landscape corridor into full display. Finally, in view of these problems, it had proposed suggestions for optimization, so as to provide reference and theoretical guidance for optimizing and creating excellent landscape spatial characteristic of urban green land in Wuhua District and constructing landscape pattern of ecological security.

基于破碎度分析的耕地格局与空间分区研究——以安徽省灵璧县为例

耕地是国土资源的重要组成部分,明确耕地用途、强化耕地管制、把握耕地格局是当前耕地保护不容或缺的部分。基于县域尺度,选取Fragstats共5个一级类景观指标,分析指标数值,权重计算各类指标得到耕地破碎度空间分异情况,再利用莫兰指数与冷热点分析空间自相关性剖析耕地破碎度格局。综合指数平均值为0.47,标准差为0.19,破碎化最小值为0.16,最大值为0.77,耕地破碎化呈现出“分层分布”的空间格局特征;全局空间自相关Moran’s指数为0.322,且通过置信度检验,由局部空间自相关得到冷热点分析。最终基于综合指数划分出高中低破碎度分区,及基于冷热点分析划分出的集聚与离散分区。灵璧县空间分异格局差异性明显,整体表现为“北部高、中部低、南部低”的破碎度格局;在耕地现状上,破碎程度反映了耕地减少或调整的间接原因;在耕地保护层面,应当落实保护永久基本农田保护红线,实行小田变大田,整合闲置耕地,优化连片耕地;在耕地发展规划层面,利用破碎分区发展多价值的耕地景观,提升耕地利用效益,带动乡村整体耕地格局发展。研究成果尝试从建立耕地分区的角度分析耕地破碎度,区别当前耕地利用现状,可为当前耕地农田细碎化问题的完善和治理提供理论借鉴和参考。

基于“空间形态-破碎化-聚集度”的粤港澳大湾区森林景观格局时空演变

森林景观格局的时空演变研究能够帮助理解区域森林变化过程。传统的景观指数方法多以均值为计算结果且空间信息表达不足,基于形态学方法能够从空间上直观辨别景观类型,综合破碎化和聚集度的定量分析有助于进一步认识森林景观格局的演变特征。以1990、2000、2010、2020年粤港澳大湾区土地利用数据为基础,建立基于“空间形态-破碎化-聚集度”的综合研究框架,开展大湾区森林景观格局的时空演变研究。结果表明:(1)近30年大湾区森林形态以核心区为主,森林面积逐渐减少,而2010—2020年减少速率降低,各类型森林斑块均有所恢复;(2)整体破碎化程度较低,中部破碎化地区表现为先上升后下降的变化趋势;(3)聚集度结果表明,距离森林边界500 m内的森林斑块面积最大,约占研究区总面积的30%,而距离大于4.5 km的非森林斑块面积几乎翻倍增加,应重点关注该区域的森林损失。研究有助于全面理解森林景观格局的变化特征,相关结果可为粤港澳大湾区的森林生态修复工程、国土空间规划以及城市可持续发展提供科学依据。

铁质破片的高光谱图像识别研究

高光谱成像凭借高的光谱分辨率、图谱合一、波段多的特点,能够为待分类目标提供多维的参考信息,从而提高分类精度。爆炸破片的识别回收能够为爆炸威力的评估和防爆措施的设计提供参考。针对当前破片检测中多采用可见光波段或红外波段等单个波段进行检测,忽略了破片目标与背景对不同波长的光有着不同的吸收程度,没有将多波段破片特征充分利用,为此结合高光谱检测手段,提出了一种空间分割结合光谱信息的爆炸破片识别方法。在实验室环境下,首先采集铁质破片、石头、树叶的高光谱图像,对采集的样本图像数据做预处理,包括去噪声以及黑白校正反演反射率信息等,感兴趣区域随机提取三类样本像素点共750个,随机选取600个点作为训练集其余作为测试集,通过训练后得到预测准确度分别为88%、88%、94%的决策树模型。其次模拟了铁质破片散落在含有石头树叶的沙土中的场景并采集其高光谱数据,通过前后级联的空谱融合方法,在空域经过图像增强和去噪等预处理之后,采用边缘检测结合区域生长以及形态学处理的方法对空间图像进行分割,得到沙土上有形态的目标,空间分割的交并比(IOU)达到93.5%,真阳率(TPR)达到97.4%;然后结合光谱域训练得到的决策树模型,对各个分割区域的每个像素点进行谱域的类型识别,参与分类的三类像素点个数分别为146172、50484、213438,识别准确度分别为87%、86%、96%;最后将分类结果可视化,以每个区域像素点最多的一类代表该区域类别,将目标破片与石子和树叶两种背景进行了准确的识别,以标定后的分割图像为标准,三类像素点个数分别为155502、52045、217794,识别率分别为94%、97%、98%。分析结果表明空间分割结合光谱信息的识别方法能够有效利用空间和高光谱的特征信息对铁质破片目标进行准确识别。同时验证了使用高光谱成像进行空谱联合识别爆炸破片的科学性以及可行性,对未来采用智能化识别破片的方式评估破片战斗部威力具有一定的实用意义。

苏州市水田破碎化时空演变研究

深入揭示城镇化背景下典型区域水田破碎化时空演变过程对土地资源可持续利用具有重要意义。以苏州市为研究区,基于遥感和GIS方法,建立破碎化评价模型,借助MSPA方法系统分析了其水田破碎化的时空过程及其影响因素。结果表明:对应于研究区平原水田的面积下降,最大斑块化指数等景观格局指标反映了其破碎化的变化趋势;研究区水田破碎化空间格局变化明显;2000—2020年,水田无破碎化面积比例减少,中、高破碎化面积上升。研究区水田有破碎化增加转换成建设用地型和破碎化增加型两种主要模式,城镇建设用地扩张是研究区水田破碎化的主要驱动因素。苏州市水田在面积下降的同时其破碎化程度增加。研究结果可为研究区农地可持续利用和土地利用优化提供参考。

长白山区露水河林业局森林景观格局动态变化分析

天然林保护工程的实施改变了森林景观日益破碎化的格局,因此通过研究天保工程实施背景下森林景观格局的变化,可以说明天保工程背景下经营模式的转变是否对森林景观变化趋势起到积极的作用;同时为今后天然林保护工作措施的改进提供科学依据。通过研究利用景观格局指数计算方法,对1987—2017年露水河林业局实行天然林保护工程前后其森林景观格局的变化进行分析,结果表明:研究区域内林地为优势景观;非林地面积占比较小且面积逐年递减,林地内部相互转化,其中大约26.2%~38.6%的针阔叶林转变为混交林。研究区域内NP指数下降到7695,SHDI指数始终保存在1.1~1.4。研究区域内商品林区NP指数由9905下降到9225,公益林区NP指数由从13474下降到11001。商品林区,公益林区SHDI指数在0.9~1.2浮动,SHEI指数较高。景观类型总体上分布均匀,多样性水平较低。

四川洪雅县森林破碎化分析及生态空间格局优化--基于MSPA与MCR模型分析

文章运用MSPA与MCR模型,对2005—2018年洪雅县森林破碎化情况进行量化分析,构建森林生态空间格局并提出优化策略。结果表明:2005—2018年洪雅县森林破碎化程度增强,且中北部地区森林破碎化情况最为显著,森林完整性指标总体下降465%,破碎度和连通性指标总体上升分别为264%和303%,基于MSPA模型提取出2个森林孤岛修复区、10个森林核心修复区,通过MCR模型生成33条森林潜在廊道,并划定森林核心区、森林管控区、森林过渡区以及可建设区4个森林用地管控区域。最后提出“整体修复-组团管控-优化布局-限制扩张”4类森林生态空间格局优化策略,为洪雅县森林保护与可持续规划提供思路。

耕地景观破碎化同区域粮食产量变化的相关性探析

利用中国科学院30 m分辨率的土地利用影像与粮食产量数据,借助景观生态学方法和空间统计分析手段,在景观级别、乡镇尺度上探究潜江市水田、旱地景观破碎效应同粮食产量变化的相关关系。结果表明,2010—2018年研究区的粮食产量基本维持稳定;东南部乡镇耕地的内部结构基本维持稳定,其余各乡镇呈现增加的变化态势,且这些乡镇在2010年后也大多转增为减;水田景观破碎效应受斑块数量的影响较大,旱地景观破碎化受斑块形状和内部结构的影响较大。为保障区域粮食产出均衡,应重点改善区域的旱地景观形状,治理内部结构破碎化,保障区域产粮安全。