Due to its unique geographical location and regional climate, the Yellow River and its tributaries are prone to ice jams almost every spring. Ice jams can cause levees to burst, leading to severe flooding, property damage, and human casualties. Hence, there is an urgent need to carry out observations of ice conditions and make risk assessments of ice jam occurrence. Field observation is the most reliable technique, but it is usually too expensive and time-consuming, which has led to the evaluation of applied remote sensing for data capture and analysis. Owing to the factors of timeliness, image resolution, human safety, and cost, satellite or manned aerial remote sensing cannot fully meet the requirements of ice condition observation. An unmanned aerial vehicle (UAV) remote sensing system is proposed for the collection of river ice imagery, providing the benefits of low cost, flexible launch and landing logistics, safety, and appropriate hyperspatial image resolution. One Inner Mongolian segment of the Yellow River was chosen as a test area to demonstrate key technologies and specific procedures of observation and assessment of ice conditions using the UAV system. The specific UAV remote sensing system and its components are introduced along with the procedures of UAV operation and imagery acquisition. Image preprocessing techniques and ice information extraction are described in detail followed by analysis and risk assessment of the ice conditions based on the resulting panoramic imagery. Results prove the feasibility and effectiveness of applying the fixed-wing UAV system to rapid observation and risk assessment of ice jam formation over the Yellow River under harsh weather conditions including low temperatures and strong winds. (c) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI:10.1117/1.JRS.6.063586]

Experimental observation and assessment of ice conditions with a fixed-wing unmanned aerial vehicle over Yellow River, China

The technique of image matching is the basis of image fusion,image mosaic and scene 3D reconstruction.In the paper a novel image registration method based on SUSAN operator is proposed.Firstly,Corner points are extracted by using SUSAN(Smallest Univalue Segment Assimilating Nucleus) operator.Then matched corner points are selected through coarse matching and fine matching.Based on such corner pairs,aerophotos are registered automatically.

Automatic registration of aerophotos based on SUSAN operator

The georeferencing procedure of high resolution satellite images (HRSIs) using proper mathematical models is an important step in 3D spatial information extraction. Since the 2000s, line-based math...

Accuracy improvement of high resolution satellite image georeferencing using an optimized line-based rational function model

Unmanned Air Vehicles (UAVs) are gaining increased importance in a variety of applications, both military and civilian, due to their ability to carry out critical missions with reduced costs and minimal risks to human life. However, a UAV system is essentially a complex distributed system involving multiple heterogeneous software and hardware modules. The seamless integration of such components is one of the key challenges facing UAV systems. Furthermore, developing and maintaining a UAV system is a highly expensive and time consuming process. In this paper we present the framework a novel distributed component-based software framework that facilitates rapid development, seamless integration and run-time maintenance of UAV systems. The framework is composed of four main components: the Mission Planner, the Task Executer, the World Model, and DicoCom. Whereas the first three components facilitate the creation and execution of UAV missions, the latter is a generic component model that constitutes the basis for creating distributed components with different interaction patterns. Furthermore, the framework provides a scripting language, called DicoScript, used for binding the distributed components together and describing high level UAV missions. This paper presents the framework design goals and architecture, elucidates the main framework components and the DicoScript language, and describes the use of the framework to create UAV-based search and rescue application.

Distributed component-based framework for Unmanned Air Vehicle systems

The fastest and most economical method of acquiring terrain images is aerial photography The use of unmanned aerial vehicles (UAVs) has been investigated for this task However, UAVs present a range of challenges such as flight altitude maintenance This paper reports a method that combines skyline detection with a stereo vision algorithm to enable the flight altitude of UAVs to be maintained A monocular camera is mounted on the downside of the aircraft’s nose to collect continuous ground images, and the relative altitude is obtained via a stereo vision algorithm from the velocity of the UAV Image detection is used to obtain terrain images, and to measure the relative altitude from the ground to the UAV The UAV flight system can be set to fly at a fixed and relatively low altitude to obtain the same resolution of ground images A forward-looking camera is mounted on the upside of the aircraft’s nose In combination with the skyline detection algorithm, this helps the aircraft to maintain a stable flight pattern Experimental results show that the proposed system enables UAVs to obtain terrain images at constant resolution, and to detect the relative altitude along the flight path

Monocular Vision System for Fixed Altitude Flight of Unmanned Aerial Vehicles

With the development of Unmanned Aerial Vehicles (UAVs) remote sensing technique, some researchers began to apply the UAV imagery to investigate Yellow River's dike hazards. There has been an urgent need for establishing automatic and accurate registration techniques of UAV remote sensing imagery. High-precision image registration will enhance the reliability of the investigation. As the Yellow River is very wide, it is very difficult to find enough Ground Control Points (GCP) and the limited GCPs are usually distributed unevenly. Therefore, the traditional point-based image registration approach cannot satisfy the requirements of imagery registration. However, the river basin contains linear features richly. This paper proposes a line-based registration approach for UAV remote sensing imagery of the wide-spanning river basin. This method regards the segment straight line as the registration primitives. After detect the primitives of input images, we estimate the parameters of transformation model between reference-image and registering-image with Modified Iterated Hough Transform (MIHT). Experiments using the UAV imagery of Ning-Meng section of Yellow River conclude that this is a robust method for registration for UAV remote sensing imagery of wide-spanning river basin.

Line-based registration for UAV remote sensing imagery of wide-spanning river basin

Two-dimensional model tests combined with PIV technology were conducted to study the failure behavior of strip footing on geosynthetic-reinforced granular soil foundations on a mesoscale. The results showed that geosynthetic reinforcements improve the bearing capacity of granular soil foundations; however, the effectiveness of the reinforcement was affected by the position, length, and number of geosynthetics. The mesoscale factor affecting the reinforcement effectiveness was the size of the sliding wedge in the foundation, which was changed by the embedded geosynthetics. As the depth, length, number, and vertical spacing of the reinforcements varied, three possible failure modes occurred in the reinforced foundations: failure above the top reinforcement layer, failure between reinforcement layers, and failure similar to footings on the unreinforced foundation.

/pdf/mesoscopic-failure-behavior-of-strip-footing-on-geosynthetic-1xwzt89a.pdf

Mesoscopic Failure Behavior of Strip Footing on Geosynthetic-Reinforced Granular Soil Foundations Using PIV Technology

Granular column collapse: Analysis of inter-particle friction effects

The worldwide problem of reservoir sedimentation has perplexed the water conservancy industry. The problem of reservoir sedimentation is particularly serious in sandy rivers in China and directly affects the normal function of reservoirs. Due to its effect on the economy and environmental protection, the self-priming pipeline dredging and sediment discharge technology has broad application prospects. Nevertheless, there are pressing problems in the transportation of slurry particles in the pipeline system of this new technology. The purpose of this study is to use physical model tests to analyze the influence of the sediment transport rate and pipeline velocity on the motion state of particles (aggregation transport, jump transport, and suspension transport) when a heterogeneous flow with different particle sizes is transported in the pipeline. The results indicate that under the same pipeline velocity and sediment transport rate, the thickness of the static particle accumulation layer decreases with the increase in particle size in the state of aggregation and transportation, and the smaller the particle size, the greater the particle movement speed in the case of aggregation and suspension transportation. During jump transportation, the velocity of particles above the critical inflection point Y’ increases with the decrease in particle size. The opposite is found below the critical inflection point Y’. At the same particle size and sediment transport rate, when the pipeline velocity increases, the particle transport transits from aggregation transport to jump transport and then to suspension transport. The larger the pipeline velocity, the greater the overall movement speed of particles. When gathering and conveying, if the pipeline flow rate increases by 1.5, the maximum movement speed of particles increases by 3.3. The curvature of the vertical velocity curve of the particles during jump transportation is not affected by the pipeline velocity. The particle velocity at the highest point increases with the increase in the pipeline velocity. During suspension transportation, the difference between the maximum and minimum vertical particle distribution velocities is exponentially related to the pipeline velocity. At the same pipe velocity and particle size, the overall particle velocity decreases with the increase in sediment transport rate.

/pdf/study-on-the-motion-characteristics-of-particles-transported-il0b1khp.pdf

Zhongmei Wang

Papers

Line-based registration for UAV remote sensing imagery of wide-spanning river basin

Mesoscopic Failure Behavior of Strip Footing on Geosynthetic-Reinforced Granular Soil Foundations Using PIV Technology

Granular column collapse: Analysis of inter-particle friction effects

Study on the Motion Characteristics of Particles Transported by a Horizontal Pipeline in Heterogeneous Flow