CALINE4模型扩散参数的城市建筑影响

机动车尾气排放已经成为城市空气污染的主要原因之一,为了更好地了解机动车尾气扩散,在GIS领域为机动车尾气的治理提供帮助,该文基于CALINE4模型对城市道路中机动车尾气的扩散特性进行研究。通过ENVI-met软件模拟验证了建筑物对污染气体扩散的显著影响,在CALINE4模型的基础上综合考虑了道路两侧建筑物对机动车尾气的反射作用和阻塞作用,结合道路的街谷高宽比和阻塞比的概念,提出了一种在建筑物影响下CALINE4模型中扩散参数的修正方案,并定性分析了建筑物对模型中扩散参数的影响以及对机动车尾气扩散过程的影响。分析结果表明,建筑物对机动车尾气的扩散有明显的反射与阻塞作用,尤其在建筑密集的区域会产生二者的叠加,使该区域污染物浓度分析更加复杂。     

基于Pix4Dmapper的无人机低空摄影测量数据处理

随着科技发展,无人机的使用就像汽车一样应用于各个领域,成熟的航空摄影测量理论为无人机在测量方面的使用提供了坚实的基础,而后处理成像软件通过提供三维模型来实现数据的精确可视化,更进一步提高了无人机的有效性。本文利用航空摄影测量的中心投影原理,提出基于Pix4Dmapper的无人机低空摄影测量数据处理流程,对经过空中三角测量和相机校准的航摄像片经过光束法区域网平差、空三加密、点云编辑、滤波处理,生成高精度的Google瓦片、正射影像图(DOM)、三维点云模型、数字表面模型(DSM)、数字高程模型(DEM)、数字地面模型(DTM),经过多次应用表明:处理成果能够满足应用需求,极大促进了摄影测量技术的发展。     

Vehicle trajectory modelling with consideration of distant neighbouring dependencies for destination prediction

Vehicle trajectory modelling is an essential foundation for urban intelligent services. In this paper, a novel method, Distant Neighbouring Dependencies (DND) model, has been proposed to transform vehicle trajectories into fixed-length vectors which are then applied to predict the final destination. This paper defines the problem of neighbouring and distant dependencies for the first time, and then puts forward a way to learn and memorize these two kinds of dependencies. Next, a destination prediction model is given based on the DND model. Finally, the proposed method is tested on real taxi trajectory datasets. Results show that our method can capture neighbouring and distant dependencies, and achieves a mean error of 1.08 km, which outperforms other existing models in destination prediction significantly.     

Measuring the area of cultivated land reclaimed from rural settlements using an unmanned aerial vehicle

Journal of Geographical Sciences - Investigating and monitoring the area of cultivated land reclaimed from rural settlements is important to optimize rural land use and understand spatial patterns....     

Experimental study on the soil thrust of underwater tracked vehicles moving on the clay seafloor

As the soil traction of the track system consisting of a track plate and protruded grousers is generally higher than that of a comparable wheel system, underwater tracked vehicles are the favored platforms for heavy-weight remotely operated vehicles (ROVs). When an underwater tracked vehicle moves on the seafloor, the track system laterally transmits an engine torque to the soil-track interface, resulting in slip displacement and an associated soil thrust acting as a traction force. Therefore, to evaluate the mobility of underwater tracked vehicle, it is critical to evaluate the soil thrust of the track system based on the soil-track interaction. Unlike the soil thrust of sandy soils, a reliable soil thrust assessment method accounting for the failure mechanism of clayey soil has yet to be developed in spite of its significance. An experimental study on the mechanism of the soil thrust of clayey soil was thus performed. Model track experiments were conducted on a model track system with clayey soil. Based on the experiment results, the mechanism of the soil thrust of clayey soil was investigated and was compared with the mechanism of soil thrust derived from the previous soil thrust assessment methods using sandy soil. Particular attention was given to the development of a new soil thrust prediction model for the track system on clayey soil using the limit equilibrium analysis technique.     

Analytical design of an underwater construction robot on the slope with an up-cutting mode operation of a cutter bar

In this paper, the movements of the analytical models of complete underwater tracked vehicle (UTV) and cutter bar (CB) tool systems on a surface as well as their movements up and down a slope in the up-cutting mode operation are fully studied and analyzed. First, the mathematical expression of the mechanics, for which the forces, moments, and energy from the CB to the UTV are analyzed, is related. Next, analyses on the systemic parameters and their sensitivity are conducted to observe the variations of the operational and geometric parameters, as well as the cutter-tool and material-condition effects on the force, moment, and power components. Also, a design process composed of seven typical steps is proposed as the reference of a trencher-machine design. The important design parameters of the trenching machine such as the length of the CB, the nose radius of the CB, and the height of the pivot point are designed according to the proposed design process; furthermore, these parameters are used for the estimation of the slope-angle range when the trencher system is working on the slope. To demonstrate the application of derived equations to practical problems of the machine design, a number of numerical simulations are performed. Through the numerical simulations, the important parameters of the system such as the tangential force, F_t, the tractive thrust, H, the normal reaction, V, the cutting moment, M_c, the maximum carrier weight, W, and the available power are analyzed. From these, as a reference data for the designing of a trencher machine, the previous design of the system can be improved.     

面向地理信息大数据的时空事件关系可视化分析框架

不同类型的地理信息大数据蕴含了丰富的时空关系,反映个体或者群体时空事件之间的变化模式,在资源、环境、交通等领域的智慧应用中起到关键性作用。然而,地理信息大数据拥有的多尺度和多语义特性,在挖掘地理信息大数据的时空关系时会存在许多困难。如何有效地构建多尺度多语义时空关系,并直观地表达这些时空关系是一个重大挑战。本文设计了一种时空事件关系可视化分析框架,通过定义事件间时空关系的描述,设计了一种多视图协同的可视化分析方法,结合时空关系的可视化协同交互,实现地理信息大数据时空事件可视分析。基于时空轨迹数据,通过试验说明该方法可以探寻时空事件及背景间的时空关系,实现时空事件的交互可视分析。     

面向城市道路的多传感器融合定位导航技术

方便地获取高精度、高可靠的轨迹数据是交通、旅游等行业智能化发展的关键。鉴于此,本文设计一款集GPS、SINS和OBD于一体的多源车载组合导航系统来收集轨迹数据,提出数据融合的方法来弥补因传感器噪声导致的位置累积误差,并在GPS失锁时有效预测轨迹位置信息。此方法通过梯度提升与决策树相结合建立INS误差补偿模型,并引用粒子群算法优化模型的回归参数,可有效避免误差积累;再利用联邦滤波器实现GPS、SINS和OBD数据融合,提高了轨迹信息的准确性。实际道路测试证明,基于此方法的组合导航系统,在多种路况下可收集连续精准的轨迹数据。     

无人机航测在长江岸线测绘中的应用

无人机航测是一项新兴的测绘技术,以其测图效率高、受地面约束小、自动化成图等优点深受测绘生产单位的青睐。本文利用拓普康天狼星Sirius Pro无人机对泰州的长江岸线进行了航测,生成了高分辨率影像图、数字高程模型、数字地表模型,经检验航测成果的精度满足大比例尺测图的要求,为长江岸线的测绘提供了新的测绘方法,对无人机航测实践具有很好的指导借鉴作用。     

车载测量系统教学试验设计

针对测绘学科从传统测绘到数字化测绘,再到信息化测绘的发展,分析了当前测绘教学模式中存在的一些不足,提出将车载测量系统新技术引入到本科生教学。分析了课堂进行车载测量系统学习的前沿性和可行性,并根据其原理进行课程和试验的模块化设计。结果表明,测绘新产品能够激发学生学习兴趣和创新能力,提高专业技能,符合测绘教育的现代化的要求。