临汾市近20年植被覆盖度遥感估算及动态变化分析

植被覆盖度是衡量植被生长状况的指标，对分析评价区域生态环境具有重要意义。以临汾市1998年、2007年和2018年Landsat遥感影像作为数据源，利用ENVI和ARCGIS软件，通过计算归一化植被指数（NDVI）值，利用像元二分模型，对临汾市近20年的植被覆盖度及其动态变化进行分析。分析结果显示:1998年、2007年和2018年临汾市的平均植被覆盖度分别为45.92%、58.76%和60.09%，处于递增的态势。在这20年间，极低覆盖度和低覆盖度的植被面积都有减少，而中等覆盖度、高覆盖度和极高覆盖度的植被面积增加。高覆盖度和低覆盖度的植被面积变化最大，高覆盖度的植被面积增加了3 063.14 km²，约占临汾市总面积的15.21%；低覆盖度的植被面积减少了3 192.38 km²，约占临汾市总面积的15.85%。说明临汾市的生态环境有所改善，这与该区水土保持项目的实施以及封禁治理有关。     

Escape trajectories are deflected when fish larvae intercept their own C-start wake

Fish larvae may intercept their own wake during sharp turns, which might affect their escape performance. We analysed C-starts of larval zebrafish (Danio rerio, Hamilton, 1822) using a computational fluid dynamics approach that simulates free swimming (swimming trajectory is determined by fluid forces) by coupling hydrodynamics and body dynamics. The simulations show that fish may intercept their own wake when they turn by 100–180°. During stage 1 of a C-start, the fish generates a strong jet at the tail that is shed into the wake. During stage 2, the fish intercepts this wake. Counterfactual simulations showed that wake interception increased the lateral force on the fish and reduced the fish''s turning angle by more than 5°. Wake interception caused no significant acceleration tangential to the trajectory of the fish and did not affect total power output. While experimental and simulation evidence suggests that fish larvae can either undershoot or intercept but not overshoot their wake, our simulations show that larger fish might be able to avoid intercepting their wake by either under- or overshooting. As intercepting its own wake modifies the fish''s escape trajectory, fish should account for this effect when planning their escape route.     

Investigation of the sky optical conditions over selected stations in the major vegetation zones of Nigeria

Data-set of monthly global solar irradiance covering periods of at least 20 years over selected stations in Nigeria have been utilised to investigate the sky optical conditions over the five major vegetation zones of the country. The monthly variation of the clearness index for the selected stations has been investigated. Results show that the clearness index has its minimum in August which indicates reduced insolation during the monsoon month of August and maximum around November, December and February which shows high insolation. Statistical analysis of the monthly clearness index which gives the percentage depletion by the sky of the incoming insolation and the subsequent characterisation of the sky conditions based on this were also done. The results show that cloudy sky conditions prevail in the rainforest and mangrove swamp zones (e.g. Lagos, K_T=0.40) while clear sky conditions prevail in the Sudan and Sahel vegetation (e.g. Nguru K_T=0.66) and Kano (K_T=0.65).     

Equality in death: Sigurd Lewerentz and the planning of Malmö Eastern Cemetery 1916–1973

The exponential growth of industrialized cities at the turn of the twentieth century led town planners and architects in Sweden to design new cemeteries and engage in the discussion with novel approaches to commemoration. Malmö Eastern Cemetery (1916–1973) was designed by Sigurd Lewerentz (1885–1975) and represented an ambitious experiment: a new scale of cemetery landscape, which involved planting vegetation anew and detracted from sweeping picturesque designs. This paper analyses how Lewerentz's approach to the equality of individual tombstones affected his design of Malmö Eastern Cemetery, both in terms of burial spaces for individuals and the commemorative public realm. Based on archival research and field work, this paper delves into the interplay between the cemetery designers and the different urban planners of Malmö over a period of dramatic transformation in the eastern districts of the increasingly industrialized city. Although Lewerentz initially differentiated between tombstones, after 1922 he reconsidered his cemetery plans, setting standards that made commemoration accessible to everyone while limiting individual choices. Lewerentz's homogenizing decisions in planning Malmö cemetery provide a lens through which to examine how equality has shaped discussions around commemoration, representing ideals of societies across history and the underlying tensions between individual freedom and society.     

舰空导弹拦截反舰导弹决策模型

阐述了利用舰空导弹拦截反舰导弹的作战使用问题是海军对空防御研究中的重要课题,而舰空导弹对反舰导弹的拦截决策又是此课题中的一个重要方面,立足于海军对空防御作战的实际需要。利用0-1整数规划的方法,研究了编队及单舰在受到敌多枚反舰导弹攻击的情况下,舰空导弹对反舰导弹进行拦截的最佳拦截方案的统一优化决策模型。     

软交换网络监控模型的设计与应用

随着以软交换为核心的下一代网络的发展,如何在软交换网络中实现监听和控制成为了热点问题.文章重点研究了软交换网络自身的特性,分析了现有的软交换网络监听接口规范存在的不足之处,给出了一种可以同时实现对网络监听和接续控制的软交换网络监控模型设计方案.文章最后以SIP(会话初始协议)网络为例对该方案的应用进行了描述,并对监控的流程进行了具体的说明.     

新疆和田植被水分利用效率的SEM-ANN模型构建

水分利用效率(WUE)反映了消耗单位质量水所制造的干物质量,是评估植被生长适宜性的综合指标,但是WUE的复杂影响机制使得区域多种因素的驱动贡献不甚明晰.为了探究多种因素对WUE的直接或间接影响关系,以求得到更好的WUE模拟效果,本研究构建了结构方程模型(SEM)与人工神经网络(ANN)相耦合的SEM-ANN模型.由SE...     

斑块状植被遥感检测研究进展

斑块状植被是世界上干旱—半干旱区常见的景观类型,对于它们的形成、结构和演替研究能够提高人们对干旱—半干旱地区生态系统动态及其重要的生态水文过程的理解,具有重要的理论研究意义和应用价值.传统的基于地面调查和长期定位观测的方法观测范围有限,已无法满足目前区域斑块状植被分布及其空间格局特征研究的需要.利用遥感技术快速重复获取...     

簇状分布的刚性双层植被明渠紊流特性分析

采用RNG k-ε 紊流模型,对簇状分布的刚性双层植被明渠水流进行了模拟和分析;根据时间及空间的双平均方法对植被明渠水流的流速及紊动参数进行了统计。结果表明:簇状分布的植被明渠水流可以分为植物区、间隙区及主流区,不同区域时均流速的大小和分布各异;双层植被明渠水流中,时均流速垂线分布在近床面、低植物顶部附近及高植物顶部附近均出现拐点,脉动强度和紊动能的最大值出现在高植物顶部附近。     

全尺度林地景观的创造性管理——基于 瑞典农业科学大学阿尔纳普风景实验室项目 研究

20世纪80年代,瑞典农业科学大学风景园林系教授罗朗·古斯塔文森在阿尔纳普校区创建风景实验室,融汇三脉斯堪的纳维亚风景园林的历史源流,即农林、早期自然保护与城市公园,系统性、全尺度地探索一片幼林地风景的创造性管理。风景实验室将林地规划为多林分组合,作为营林、风景园林设计与教学,以及公共游览的同一场所,因循植物景观的自然形态与活态结构,善用林室氛围景观,实践一种协同营林、生态保育和风景审美效用的管理式设计,为发展多用途城市林地提供创新实验场所。在风景实验室教研组发表的项目论文与报告书等文献资料的基础上,说明主要实验原则与方法,解析创造性管理的风景园林设计主线,简述由风景实验室延伸出的设计概念与项目。