Automatic delineation of drainage basins within digital elevation data using the topographic primal sketch

A new technique for automatic delineation of drainage basin perimeters within digital elevation data is described which applies the topographic primal sketch to digital terrain data, and is much more natural and much more efficient than usual methods that rely upon moving a window over the array of data. This method is able to find drainage channels, mark water flow direction, and recover drainage basin areas. Results appear to be comparable to drainage patterns which can be interpreted visually from contours of the elevation data.     

浅析宏观观测网的建设

结合临汾市地震宏观观测网的建设情况,叙述了宏观观测网建设的必要性,并就当前地方地震系统怎样抓好地震监测主战场的工作提出了一些看法。     

国有大型企业网络变化及对区域经济发展的影响——以中国一拖为例

本文采用企业跟踪调查法,结合中国一拖的案例研究,对改革开放以来大型国有企业的网络变化进行了深入分析。同时探讨了企业网络变化对区域经济发展产生的影响。     

Deep learning for geometric and semantic tasks in photogrammetry and remote sensing

ABSTRACT

During the last few years, artificial intelligence based on deep learning, and particularly based on convolutional neural networks, has acted as a game changer in just about all tasks related to photogrammetry and remote sensing. Results have shown partly significant improvements in many projects all across the photogrammetric processing chain from image orientation to surface reconstruction, scene classification as well as change detection, object extraction and object tracking and recognition in image sequences. This paper summarizes the foundations of deep learning for photogrammetry and remote sensing before illustrating, by way of example, different projects being carried out at the Institute of Photogrammetry and GeoInformation, Leibniz University Hannover, in this exciting and fast moving field of research and development.     

Analysis of spatial water quality and stream networks in the southern Cotswolds during and after the drought of 1976

A study of water chemistry changes and stream network changes during and immediately after the 1976 drought is made in an area to the north and east of Bristol. In particular, contrasts are made between the Cotswold Limestone dip slope and the Severn Clay Vale. Immediately following the end of the drought a solute flushing effect was observed on the clay streams, whilst network extension on limestone streams incorporated new source areas and maintained higher solute concentrations throughout the post-drought period investigated.     

The permanence of stream networks in Britain

Stream networks used in studies of basin morphometry, network topology, flood hydrology, and sediment production should be defined as precisely as possible. Previous work has drawn attention to the way in which stream network definition varies on maps of different scales, on maps employing different conventions devised in relation to the dynamic network, and according to whether maps, remote sensing or field survey sources are used. Networks also vary in extent according to the date of survey and after considering the instructions to surveyors it is shown that such changes, over periods of 100 years reflect changes in network extent. For three areas of Britain, network change can be identified by comparison of maps of different dates, by comparison of these changes with the results of field survey, and by reference to dateable features such as inclosure boundaries. Changes of drainage networks since the nineteenth century are shown to be significant in extent and they have often occurred as a result of the replacement of flushes by clearly defined stream channels. This transformation has often occurred as a result of new or modified systems of stormwater drainage from roads, tracks or farms, and the planning of the future disposal of road drainage should be considered carefully in relation to such stream network changes. The changes of drainage networks identified from maps of different dates and editions can provide a useful data base for studies of network topology and may also be significant in relation to palaeohydrological investigations.     

The relation of chain length to chain curvature in natural channel networks

Analyses of three different areas indicate that chain curvature controls chain length indirectly through valley-side plan form. It follows that, since concave chains on one side of a stream are usually matched by convex chains on the other side, tributary development and abstraction do not occur independently along either side of a stream, as has hitherto been assumed.     

Characteristics of multiple-fan ventilation networks

Summary The definitions of system pressure loss (mine head) and system resistance, which are traditionally associated with single-fan networks, are applied to multiple-fan ventilation networks. The system characteristics, relations among air power, pressure loss, air quantity and resistance, are analysed by introducing the concept of subsystems. These subsystems are associated with the fans located in a cutset of the network.For a multiple-fan network, the resistances for the subsystems and total system are dependent on the quantity ratios of the subsystems. In general the pressure loss of a subsystem or a total system does not vary as the square of the corresponding air quantity. If the quantity ratios of subsystems are all held constant, then the resistances become constant and the pressure losses are predictable from the quantities employing the square law. The system resistance has a minimum value under the natural-splitting flow pattern. Being independent of the value of system quantity, the minimum system resistance provides a basis for comparing the different networks.     

Solar origin of geomagnetic storms and prediction of storms with the use of neural networks

This review deals with how the changes of the large-scale solar magnetic fields are related to the occurrence of solar phenomena, which are associated with geomagnetic storms. The review also describes how artificial neural networks have been used to forecast geomagnetic storms either from daily solar input data or from hourly solar wind data. With solar data as input predictions 1–3 days or a month in advance are possible, while using solar wind data as input predictions about an hour in advance are possible. The predictions one hour ahead of the geomagnetic storm indexD _st from only solar wind input data have reached such high accuracy, that they are of practical use in combination with real-time solar wind observations at L1. However, the predictions days and a month ahead need to be much improved in order to be of real practical use.     

川东石炭系储层人工神经网络法预测试验

针对川东地区高陡构造下石炭系储层埋藏深、地震反射波信噪比低等特点，提出了一套利用地震资料经人工神经风格训练进行气藏预测的方法，特别是在网络训练前利用模型法对高陡构造和预测点先行归位计算，经实验检验，取得了好的效果。