Evaluating techniques for mapping island vegetation from unmanned aerial vehicle (UAV) images: Pixel classification,visual interpretation and machine learning approaches

We evaluate three approaches to mapping vegetation using images collected by an unmanned aerial vehicle (UAV) to monitor rehabilitation activities in the Five Islands Nature Reserve, Wollongong (Australia). Between April 2017 and July 2018, four aerial surveys of Big Island were undertaken to map changes to island vegetation following helicopter herbicide sprays to eradicate weeds, including the creeper Coastal Morning Glory (Ipomoea cairica) and Kikuyu Grass (Cenchrus clandestinus). The spraying was followed by a large scale planting campaign to introduce native plants, such as tussocks of Spiny-headed Mat-rush (Lomandra longifolia). Three approaches to mapping vegetation were evaluated, including: (i) a pixel-based image classification algorithm applied to the composite spectral wavebands of the images collected, (ii) manual digitisation of vegetation directly from images based on visual interpretation, and (iii) the application of a machine learning algorithm, LeNet, based on a deep learning convolutional neural network (CNN) for detecting planted Lomandra tussocks. The uncertainty of each approach was assessed via comparison against an independently collected field dataset. Each of the vegetation mapping approaches had a comparable accuracy; for a selected weed management and planting area, the overall accuracies were 82 %, 91 % and 85 % respectively for the pixel based image classification, the visual interpretation / digitisation and the CNN machine learning algorithm. At the scale of the whole island, statistically significant differences in the performance of the three approaches to mapping Lomandra plants were detected via ANOVA. The manual digitisation took a longer time to perform than others. The three approaches resulted in markedly different vegetation maps characterised by different digital data formats, which offered fundamentally different types of information on vegetation character. We draw attention to the need to consider how different digital map products will be used for vegetation management (e.g. monitoring the health individual species or a broader profile of the community). Where individual plants are to be monitored over time, a feature-based approach that represents plants as vector points is appropriate. The CNN approach emerged as a promising technique in this regard as it leveraged spatial information from the UAV images within the architecture of the learning framework by enforcing a local connectivity pattern between neurons of adjacent layers to incorporate the spatial relationships between features that comprised the shape of the Lomandra tussocks detected.     

营口-潍坊断裂带新生代运动学特征

营口-潍坊断裂带在新生代时期对渤海湾盆地东部构造、沉积及油气成藏规律等方面具有重要影响和控制作用.依据大量实际地震资料,从剖面上识别出了花状构造、丝带效应、反转构造等营口-潍坊断裂带新生代时期走滑活动的标志,在平面上识别出了4种组合构造样式,在此基础上,应用拉分盆地走滑量计算的理论模型,对营口-潍坊断裂带新生代时期的走滑位移量进行了初步估算,认为营口-潍坊断裂带在新生代时期具右旋走滑活动特征,其主要走滑活动表现为3期,分别为始新世早期、渐新世早-中期和上新世晚期-第四纪,新生代累计右旋走滑位移量约为10～20 km.     

南麂列岛大沙岙沙滩贝类的时空分布

南麂列岛作为观光旅游的休闲去处正在日益升温,其中沙滩游玩是最大的活动亮点,大沙岙是南麂列岛最具代表性的沙滩,沙滩内生活着较多贝类,随大量人员的涌入和沿岸环境污染的日趋加重,大沙岙沙滩贝类的栖息地环境受到了较大程度的危害、人为活动正影响着贝类的生长发育。为探明近年来大沙岙贝类种类、数量及群落结构的变化,在南麂列岛国家海洋自然保护区建立初期(1992年)生态调查的基础上,于2003年再次对大沙岙贝类进行了采样分析,结果表明:大沙岙沙滩12种贝类的平均生物量和栖息密度分别为30.16g/m2和20个/m2,北断面开放区贝类的平均生物量和栖息密度(13.98g/m2和11个/m2)明显少于受监控的南断面核心区(46.33g/m2和30个/m2),贝类的平均生物量和栖息密度的垂直分布低潮区(48.43g/m2和31个/m2)高于中潮区(28.03g/m2和20个/m2),贝类的平均栖息密度7月高于3月,北断面贝类的季节变化、多样性和均匀度指数大于南断面。与建区初期同季调查资料比对发现,2003年北断面贝类数量下降幅度(14倍)显著大于南断面贝类下降幅度(1倍)。分析认为,自然环境变化和人为采捕是影响沙滩贝类数量下降的主要外部因子。     

Marine reserve phenomenon in the Pacific islands

Coinciding with increased numbers of global marine reserves, communities in the Pacific islands are establishing unprecedented number of periodically-harvested and indefinitely-closed marine reserves. An integrated ecological and social comparative methodology is used to examine the motivations and outcomes of reserves in Vanuatu. Communities establish permanent reserves due to concerns about human impacts on reefs, while others establish periodic reserves in response to declining resources. Local knowledge suggests that both reserve types are effective, although validation by underwater surveys was inconclusive. Community support for both reserve types is strong, suggesting that the marine reserve phenomenon in Pacific will continue.     

船载物探电子设备的接地问题及解决方案

船栽物探电子设备,是一个电气结合复杂的数据采集记录系统.各系统电子线路因船舶配电方式、工作环境的特殊性,其接地很重要,但容易被忽视.而接地处理不当,在使用时会受到噪声干扰、振荡;或造成仪器的输出榆入电路损坏,不能正常工作.更严重地甚至机壳漏电,危及人身安全.船栽物探电子设备接地问题.可分为"接地保护"和"接地故障"."接地保护"是将电气设备的金属外壳、支架和电缆的护套与大地等单位的金属船体(船壳)作永久性良好的电气连接,它分为保护接地和功能接地."接地故障"是指因设备不正确接地或由于绝缘层的破损、老化及环境恶劣引起绝缘电阻低下或者接地干扰等问题.文中从船载物探电子设备的使用特性出发.讨论在实际接地处理中出现问题的原因,分析了各种接地干扰的原理.并提出了相应的解决方案,对于船栽物探电子设备的实际安装应用有一定的指导意义.     

固体矿产储量估算系统的研究与实现

通过对固体矿产储量估算过程的详细调研,对储量估算过程中的单工程圈定算法、矿体剖面连接以及传统的储量估算方法中的平行剖面法和地质块段法做了详细研究,并针对储量计算的可视化及交互技术进行了研究,实现了一种基于Windows操作系统、MapGIS地理信息系统平台的固体矿产储量估算原型系统,实现了对固体矿产勘查数据的有效存储、管理、可视化分析及评价。     

基于分布式控制力矩陀螺的水下航行器轨迹跟踪控制

基于控制力矩陀螺群(CMGs)的水下航行器具有低速或零速机动的能力。采用基于分布式CMGs的水下航行器方案,并研究其水平面的轨迹跟踪控制问题。通过全局微分同胚变换将非完全对称的动力学模型解耦成标准欠驱动控制模型,并根据简化的模型构建其轨迹跟踪的误差动力学模型,将轨迹跟踪控制问题转化为误差模型镇定问题。基于一种分流神经元模型和反步法设计了系统的轨迹跟踪控制律,该控制器不需要对任何虚拟控制输入进行求导计算,且能确保跟踪误差的最终一致有界性。仿真结果表明该控制器能够实现在不依赖动力学参数先验知识的情况下对光滑轨迹的有效跟踪。     

隔板贯通式梁柱节点抗震性能试验研究

设计了低周反复荷载作用下3个十字形足尺隔板贯通式梁柱节点试件(其中2个节点的柱子浇筑了混凝土,1个为空钢管)的拟静力试验。通过研究拟静力试验所得的滞回曲线求得该节点的等效阻尼比,衡量它的耗能能力。从恢复力特性曲线得到了和一次加载相接近的骨架曲线,节点的初始刚度和刚度退化等参数。通过这些从强度、变形和能量等三方面判别和鉴定隔板贯通式梁柱节点的抗震性能,并得出了一些具有参考价值的结论。     

矿山人均保有储量:我国金属矿山合理经济开发的一个标量

文章分析对比了我国国有及非国有规模以上矿山企业的主要经济指标,认为矿业开发要走可持续发展的途径,促进矿产资源的充分、合理、有效开发,实现满足市场需求、兼顾环境保护和社会稳定的目标,就必须积极探索和慎重考虑矿山企业从业人数的合理控制问题;依据胶东大型金矿山实际资料的初步分析,明确提出"矿山人均保有储量"是制约矿山合理开发和矿业可持续发展的重要指标;矿山人均储量的合理配置和适度调控问题不仅值得进一步研究,而且应该引起有关部门的广泛注意和高度重视.