Application and experimental validation of a computational fluid dynamics (CFD)-based erosion prediction model in elbows and plugged tees

This paper presents a computational fluid dynamics (CFD)-based erosion prediction model and its application to oilfield geometries specifically elbows and plugged tees. This comprehensive procedure consists of three major components: flow simulation, particle tracking, and erosion calculation. The effect of the particle rebound model on the particle trajectories as well as erosion pattern in the elbow and plugged tee is also investigated. Experimental erosion tests were performed in both an elbow and a plugged tee to evaluate the simulation results. The results from the model show good agreement of the erosion trend with the erosion data for elbow and plugged tee geometries. Experiment confirms that a stochastic rebound model is required in simulations to give a reasonable estimate of erosion rate and pattern in a plugged tee.     

Finding of optimal binary morphological erosion filter via greedy and branch & bound searching

In this paper, an effective and efficient algorithm for finding the optimal morphological erosion filter on binary images is proposed. The design of morphological erosion filter is based on statistical method by minimizing mean square error. Traditionally, finding optimal morphological erosion filters requires searching through a large number of structuring-element combinations which is a long search and time consuming procedure. In the proposed method, the problem of finding the optimal solution is reduced to the problem of searching a minimal path on the error code graph (ECG). Since the graph satisfies some greedy criteria, only few nodes need to be traversed and examined. Experiments are conducted to illustrate the validity of our proposed method.This work is supported by National Science Council of Taiwan under grant NSC 83-0404-E-008-022.     

Accuracy and applicability of linear spectral unmixing in delineating potential erosion areas in tropical watersheds

This study was undertaken to assess the accuracy of linear spectral unmixing (LSU) in estimating fractional abundance of land cover components and to examine its applicability in delineating potential erosion areas in tropical watershed. Five image end‐members (mixed vegetation, grass, Acacia auriculiformis, bare soil and water/shadow) were selected and used in different combinations in unmixing Landsat Enhanced Thematic Mapper (ETM) into fraction images. The accuracy assessment was conducted by comparing the land cover abundance estimates derived from unmixing with the land cover abundance measured from field‐validated classified QuickBird imagery. Good agreement was obtained using a four‐end‐member combination in which shadow was eliminated. The results suggest that LSU could be implemented for soil erosion detection. In general, soil erosion increases when vegetation cover decreases; hence, we used the fraction images to derive a bare soil/vegetation cover ratio and used that as a simple indicator to map high potential erosion areas. Comparison with field assessment of actual erosion levels in the study area showed that the technique is effective in identifying areas on which erosion control efforts should be concentrated.     

动态流程的逻辑结构设计与实现*

在介绍印刷行业ERP系统应用现状的基础上,分析了其难以实施的原因,提出了在原型基础上进行局部定制的解决方案。方案的核心是允许重构物理结构的能力和采用动态流程的思想,在论述方案的必要性及可行性的基础上,详细论述了可作为行业性ERP系统参考方案的动态流程逻辑结构的设计与实现。     

Runoff mapping using WEPP erosion model and GIS tools

Soil erosion, associated with environmental impacts and crop productivity loss, is usually considered the most impacting of surface hydrology processes. Runoff plays a major role in the erosion process, but it is also important by itself as it directly influences several surface hydrologic processes. In this paper, a computer interface (Erosion Database Interface, EDI) is described that allows processing the surface hydrology output database of the Water Erosion Prediction Project (WEPP) erosion prediction model, resulting in a georeferenced estimation of runoff. WEPP output contains non-georeferenced daily information about estimated runoff at the lower end of each Overland Flow Element. EDI, when running with WEPP, allows extracting WEPP-calculated runoff values, transforming them into annual means and relocating them in a georeferenced database readable by Geographic Information Systems (GIS). EDI was applied to a 1990 ha watershed in southeast Brazil, with vegetation of mainly sugarcane, forest, and pasture. A 100-year climate simulation was used as input to WEPP, and erosion values were calculated at about six points per hectare and interpolated to a raster format. EDI was successful in preparing the database for automatic calculation of erosion and hydrologic parameters with WEPP and to restore georeferences to mean annual accumulated runoff data that were imported in the GIS as a vector database. Of all the resulting maps, the runoff map is the one that integrates all of the input parameters required for WEPP simulation, thus reflecting not only the physical environment but also crop growth and management and tillage operations. A very small correlation between runoff and erosion shows them to behave independently. Moreover, it is concluded that on analyzing runoff related to agricultural management, georeferenced runoff studies are especially important. In this context, EDI may be a useful tool to assess the effect of tillage and crop management on runoff production.     

Study of seabed elevation changes using geochemical elements

Using X-ray fluorescence spectroscopic analysis and the method of ratio matching, the mean directions of sand movement and the geochemical classifications of sand grains can be determined, from which the physical condition of seabeds (erosion or accretion) can be evaluated. This method is applied to two coasts in Japan and the results are in good agreement with the comparison of sea bottom topography measured in different years. The changes of seabed elevation are found to be quantitatively connected with the number of vectors to or from each sampling point.     

Numerical modelling of interfacial soil erosion with viscous incompressible flows

The aim of this study is to develop a numerical model for simulating surface erosion occurring at a fluid/soil interface subject to a flow process. Balance equations with jump relations are used. A penalization procedure including a fictitious domain method is used to compute the Stokes flow around obstacles, in order to avoid body-fitted unstructured meshes and instead use fast and efficient finite volume approximations on Cartesian meshes. The evolution of the water/soil interface is described by using a level set function. The ability of the model to predict the interfacial erosion of soils is confirmed by several numerical simulations.     

A water-flow algorithm for flexible flow shop scheduling with intermediate buffers

We investigate the flexible flow shop scheduling problem with limited or unlimited intermediate buffers. A common objective of the problem is to find a production schedule that minimizes the completion time of jobs. Other objectives that we also consider are minimizing the total weighted flow time of jobs and minimizing the total weighted tardiness time of jobs. We propose a water-flow algorithm to solve this scheduling problem. The algorithm is inspired by the hydrological cycle in meteorology and the erosion phenomenon in nature. In the algorithm, we combine the amount of precipitation and its falling force to form a flexible erosion capability. This helps the erosion process of the algorithm to focus on exploiting promising regions strongly. To initiate the algorithm, we use a constructive procedure to obtain a seed permutation. We also use an improvement procedure for constructing a complete schedule from a permutation that represents the sequence of jobs in the first stage of the scheduling problem. To evaluate the proposed algorithm, we use benchmark instances taken from the literature and randomly generated instances of the scheduling problem. The computational results demonstrate the efficacy of the algorithm. We have also obtained several improved solutions for the benchmark instances using the proposed algorithm. We further illustrate the algorithm’s capability for solving problems in practical applications by applying it to a maltose syrup production problem.     

A new procedure to estimate the rainfall erosivity factor based on Tropical Rainfall Measuring Mission(TRMM) data

Soil erosion by water is the most important land degradation problem worldwide.In this paper a new procedure was developed to estimate the rainfall-runoff erosivity factor(R)based on Tropical Rainfall Measuring Mission(TRMM)satellite-estimated precipitation data,which consists of 3-h rainfall intensity data.In this method,R was calculated as the product of the maximum 180-min rainfall intensity and the rainfall energy.This procedure was applied to the Daling River basin in Liaoning Province,China,R in terms...     

Surface Lagrangian Remeshing: A new tool for studying long term evolution of continental lithosphere from 2D numerical modelling

In this paper we present a new local remeshing algorithm that is dedicated to the problem of erosion in finite element models whose grid follows the movement of the free surface. The method, which we name Surface Lagrangian Remeshing (SLR), is adapted to 2D Lagrangian models which couple surface erosion with deformation of Earth materials. The remeshing procedure preserves nodes defining the surface submitted to erosion and removes nodes belonging to surface elements whose internal angles or area is critically low. This algorithm is ideally suited to track long term surface evolution. To validate the method we perform a set of numerical tests, using triangular finite elements, which compare the results obtained with the SLR algorithm with global remeshing and with analytical results. The results show good agreements with analytical solutions. Interpolation errors associated with remeshing are generated locally and numerical diffusion is restricted to the remeshed domain itself. In addition this method is computationally costless compared to classical global remeshing algorithm. We propose to couple the SLR method with the Dynamical Lagrangian Remeshing (DLR) algorithm to enable local remeshing only of Lagrangian models coupling large deformation of Earth materials with large erosion.     

A probabilistic hit-and-miss transform for face localization

Face localization is needed for any face processing procedure whose applications range from biometric identification to content-based image retrieval. It consists in giving the image coordinates of the face. In this paper we propose a probabilistic pattern matching procedure for face localization in greyscale images similar to the morphological hit-and-miss-transform (HMT), which we call probabilistic HMT (PHMT). This procedure is defined on the morphological multiscale fingerprints (MMF), which are image features extracted from the morphological erosion/dilation scale spaces. The face location is estimated as the maximum likelihood image window matching both erosive and dilative MMF models of the object. The MMF models are computed at a discrete set of scales. The MMF models may be built up from a small set of training face images and do not involve numerically sophisticated training algorithms. Training does not use non-face sample images. Therefore resampling is not needed for the construction of the MMF models. The experimental results on the NIST Mugshot Identification Database endorse our claims about the accuracy and robustness of the proposed procedure.     

Principal Feasability Studies Using Neuro – Numerics for Prediction of Flow Fields

In this paper initial studies of the application of a hybrid model using artificial neural networks and conventional numerical methods to predict – as an example – twodimensional, isothermal, steady flow fields is presented. Main topics of the work were to show the principal possibility of using ANN in fluid mechanics and, additionally, to realize the potential of incorporation a priori knowledge of physical phenomena into the training procedure. For training, as well as for rating the prediction, flow fields, consisting of velocity, temperature and pressure, were generated by numerical simulation. Major result was that prediction of the flow and especially the existance of vortices in the bodies outflow depending on the Reynolds number can be realized with a much lesser time consumption than necessary for numerical calculation. Furthermore, a priori physical knowledge could be included in the learning process with an obvious improvement of the predicting ability of the hybrid model.     

观测器型H∞控制器设计的LMI方法

观测器型控制器由于其结构简单和物理意义明确而受到广泛重视.在假定控制器 为一般的动态补偿器情况下,利用LMI技术解H∞控制器使得未知参数较多且求取过程复 杂.现利用LMI技术研究观测器型H∞控制器,则控制器参数可通过三个LMI即可获得,这 个LMI组的适定性问题用现有的工具软件即可确定.     

Hyperspectral indices for characterizing upland peat composition

The erosion of blanket peat is a major environmental issue in the UK. Maps of erosion extent and peat composition, especially humification and moisture content, would aid our understanding of the erosion process and provide information for management decisions. HyMap images, acquired as part of the SAR and Hyperspectral Airborne Campaign (SHAC), were used to test candidate indices of peat composition for eroded blanket peat in the southern Pennines. Peat physical properties, including moisture content and degree of humification (measured as transmission), were derived in the laboratory and related to the remotely sensed data. Strong correlations were found between HyMap SWIR reflectance and transmission, but other peat physical properties were not significantly correlated. Spectral indices were calculated to express the depth of cellulose, lignin and water absorption features. Strong positive correlations were found between transmission and an adjusted cellulose absorption index (CAI), r 0.71, and the gradient of its shoulders between 2020 and 2200?nm, r 0.89. Other indices also performed well. Normalized indices performed better because they allowed for differences in brightness. Higher moisture content in poorly humified peats may have reinforced the effect of deeper ligno-celluloic absorptions, but further sampling is required to test this. The results suggest the potential for hyperspectral remote sensing to provide information on surface peat composition across large areas.     

Is there something out there? Inferring space from sensorimotor dependencies

This letter suggests that in biological organisms, the perceived structure of reality, in particular the notions of body, environment, space, object, and attribute, could be a consequence of an effort on the part of brains to account for the dependency between their inputs and their outputs in terms of a small number of parameters. To validate this idea, a procedure is demonstrated whereby the brain of a (simulated) organism with arbitrary input and output connectivity can deduce the dimensionality of the rigid group of the space underlying its input-output relationship, that is, the dimension of what the organism will call physical space.     

基于GIS的龙口市泳汶河流域地貌形态定量分析

地形因子是最基本的自然地理要素,也是对人类的生产和生活影响最大的自然要素。精确的地形地貌因子分析可为经济发展、农业规划、水土流失、工程建设等研究提供有力的数据支持。应用GIS工具,对龙口市泳汶河流域作了坡度、坡向等4方面研究性的分析,得出了比较准确的数据。     

Evaluation of sediment yield by using remote sensing and GIS: A case study from the Phulang Vagu watershed,Nizamabad District (AP), India

The primary objective of this paper is to identify soil erosion zones and to suggest appropriate measures for control of soil erosion using remote sensing, GIS and conventional technique in the Phulang Vagu watershed in the Sriramsagar catchment area of Andhra Pradesh. The digital imagery data of the study area is obtained from the IRS-IC (LISS-III) satellite whereas the toposheets and rainfall data of the study area were obtained from the Survey of India. Satellite images were interpreted to prepare land use/land cover maps by using ERDAS image processing system. Out of 725.983 km 2 of the study area, about 301.435 km 2 is wasteland which is identified as susceptible for soil erosion. Toposheets of the study area were used to prepare drainage and slope maps. Drainage pattern is mainly dendritic with a density of 1.26 km -1 and the stream slope is 0.00614. The arithmetric average method is used to find average annual rainfall. The above parameters were used to calculate the amount of soil erosion from the catchment area. It was found that 882.389 m 3 km -2 year -1 of soil is being eroded from the catchment area which is more than the value adopted in the design of Sriramsagar reservoir. Therefore soil conservation measures such as vegetative cover in the waste land are needed and 12 check dam sites have been proposed by superimposing drainage map and slope map in conjunction with land use/land cover map. With these soil conservation measures, the soil erosion could be kept within the design value of Sriramsagar reservoir.     

A morphological transformation for sharpening edges of features before segmentation

A gradient-determined grey level morphological opening procedure for edge enhancement is presented. First, the maximum gradient, in the local neighborhood, forms the contribution to the erosion of the centre pixel of that neighborhood. The gradients of the transformed image are then used as contributions to the subsequent dilation of the eroded image. The enhancement procedure is illustrated on sample images representing multiple phases of soil pore structure. Histogram partitioning is applied to the sample images before and after edge enhancement. The resulting segmentation is visually better on the images after enhancement. Stereological measurements made on the segmented images show that the quantity of each phase is preserved but the degree of contact between phases is altered.     

土壤侵蚀调查中的遥感应用综述

土壤侵蚀引起土壤肥力下降、土地退化及荒漠化和生态环境恶化等一系列区域性和世界性的重大环境问题。中国是土壤侵蚀最严重的国家之一。遥感是进行环境和灾害动态监测的有效技术手段。自从20世纪70年代以来．人们就开始应用遥感技术进行土壤侵蚀的调查。对遥感技术在土壤侵蚀调查中的应用方法进行概括和汇总，分别是影像判读法、指数提取法、图像分类法、光谱分解和正射影像DEM提法等方法，分析不同方法之间的优缺点以及它们各自的适用范围，并结合当前研究的热点问题，指出未来研究的重点及趋势。     

基于数字孪生的水土流失防治责任范围变化预测模型

为建立实用、高效的水土流失防治责任范围变化预测模型,提高合规性判断的准确性,在总结水土流失防治责任范围可撤销性、时空交错性、临时性和条件适用性等4个主要动态特性的基础上,提出一种基于数字孪生的水土流失防治责任范围变化预测模型。数学模型为描述防治责任范围状态的虚拟模型,防治责任范围为物理实体,模型基于防治责任范围变化主要因素的孪生数据,对防治责任范围有效性状态进行评估和预测。结果表明：模型对防治责任范围变化进行预测的正确率提升约38%,具有良好的预测防治责任范围变化的性能,有助于进一步提升提高遥感监管成果的质量,在生产建设项目遥感监管应用领域有一定的借鉴意义。