Non-stationary variogram models for geostatistical sampling optimisation: An empirical investigation using elevation data

A problem with use of the geostatistical Kriging error for optimal sampling design is that the design does not adapt locally to the character of spatial variation. This is because a stationary variogram or covariance function is a parameter of the geostatistical model. The objective of this paper was to investigate the utility of non-stationary geostatistics for optimal sampling design. First, a contour data set of Wiltshire was split into 25 equal sub-regions and a local variogram was predicted for each. These variograms were fitted with models and the coefficients used in Kriging to select optimal sample spacings for each sub-region. Large differences existed between the designs for the whole region (based on the global variogram) and for the sub-regions (based on the local variograms). Second, a segmentation approach was used to divide a digital terrain model into separate segments. Segment-based variograms were predicted and fitted with models. Optimal sample spacings were then determined for the whole region and for the sub-regions. It was demonstrated that the global design was inadequate, grossly over-sampling some segments while under-sampling others.     

基于DEM技术的CRM系统的研究与应用

本文针对当前CRM系统存在的柔性不高、业务重组困难、工作流程自动化缺乏等问题,提出了基于动态企业建模技术的CRM系统的设计方案,并将其应用于山东烟草CRM系统的设计上。实施结果表明该方案很明显地提高了系统的柔性,满足了企业业务重组的需求,同时增加了系统工作流程的自动化,最终达到了提高企业效益的目的。     

DEM分辨率对AVSWAT2000径流模拟的敏感性分析

研究水文过程模拟时DEM分辨率对流域特征参数和产流的影响,以汉江上游马道流域为研究区,采用60m×60m、120m×120m、250m×250m、500m×500m和1000m×1000m五种不同分辨率的DEM对1981~1985年的流域径流进行模拟,结果表明:不同分辨率DEM流域地形分析计算机自动提取得到的最长河道相差较小,但河道总长、坡度等相差较大,进而影响了分布式水文模型径流模拟的效率。流域中选取4个参考研究区,用归一化的径流-河道总长比指数(NRLI)描述径流模拟与地形参数相关性,分析不同DEM分辨率对各个研究区的NRLI影响可知:低分辨率DEM的NRLI较为平缓,高分辨率DEM的NRLI在较小的研究区波动偏大,但NRLI整体趋于1,由此可以粗略推测流域内局部地区产流量,这一发现可以有效地应用于对流域水资源空间分布快速评估实践中。     

基于富钴结壳微地形的采集头载荷波动性研究

采用分形理论对海底随机地形进行重构和生成,按照海底微地形特征生成了200个随机典型地形,在此基础上对螺旋滚筒采集头切削钴结壳过程进行仿真,研究海底富钴结壳微地形的数字特征参量(高程差、高程均方差和相对平均高程)与采集头载荷波动性的关系,仿真的有效性通过实验进行验证.仿真研究结果表明,海底微地形的高程差和相对平均高程对采集头载荷波动性的影响不显著;高程均方差的变化对采集头载荷波动性的影响显著,当高程均方差大于1.75cm时,高程均方差的增加,引起载荷波动系数的显著增大.     

基于改进的最近距离法建立TIN的算法研究

在研究传统最近距离法建立TIN的算法基础上,提出了一种新的、改进的最近距离构网算法,通过实验,对该算法进行了测试,结果表明,与传统的算法相比,提高了建立不规则三角形格网(TIN)的速度,扩大了容量,为用海量数据建立DEM创造了有利条件。     

Novel Design for High Speed and Resolution Delta-sigma A/D Converter

The delta-sigma converter is one of the high speed and resolution analog-to-digital modulators. Its implementation needs the low oversampling technique and the multi-bit D/A converter. The noise induced by the multi-bit D/A converter becomes one of the key factors deteriorating the signal-to-noise rate of the delta- sigma A/D converter. A novel structure with signal unity transfunction, dynamic element matching（DEM） and noise-shaping is discussed. The method is investigated to design converter based on the proposed structure. The behavior simulation indicates that the structure and the design method are feasible.     

基于小波分解和ROI的数字高程模型表面建模

将小波多尺度分解和ROI应用于数字高程模型(DEM)的表面建模中,首先用非均匀B样条曲面进行数字高程模型地形表面建模,然后用小波多尺度的特征将地表曲面进行压缩和光顺处理.对复杂地表曲面,可能只对某些局部区域感兴趣,因此在小波多尺度分解过程中要结合感兴趣区域(ROI)的方法.本文阐述了地表曲面小波分解和ROI多分辨率表示的原理,给出了具体曲面的小波分解算法和实现结果,有效减少了曲面存储所需的空间并提高了曲面的光顺程度.     

基于小波的地形连续快速绘制技术*

利用小波变换的多分辨率特性构建了地面高程数据的动态多分辨率模型，通过小波渐近重构算法解决了多分辨率模型间的平滑过渡问题，通过缝补解决了不同分辨率地形块间的裂缝问题，实现了对大规模地形的视点相关的连续快速绘制，通过实验进行了验证。     

STREAM RESTORATION AND CRIBWALL PERFORMANCE: A CASE STUDY OF CRIBWALL MONITORING IN SOUTHERN ONTARIO

Stream restoration focusing on adaptable natural and inert material use has been implemented through soil bioengineering designs aimed at the stabilization of urbanized streams. Within each design application materials such as large wood, sediment fill and vegetation must be suited to diverse settings. This paper discusses the application of cribwalls as soil bioengineering designs found in two Southern Ontario watersheds and the criteria that influence their performance. Field measurements of cribwall cuttings, sediment sampling, erosion pin monitoring, and computer‐generated stream power analysis are used to compare design performance at several sites. It is determined that the technical specifications of the design and site characteristics such as stream power distribution, sediment, and channel planform are equally involved in long‐term streambank stability. The results indicate that cribwalls with dense cutting growth perform well on streambanks that offer a greater amount of soil cohesion, nutrients, and infiltration in the mid and upper sections of the bank. In streams with moderate channel slopes and stream power distribution that is above the watershed mean, streams with well‐developed floodplains, sinuous channel planforms, and low bank height ratios perform better than those that are confined, straightened, and have greater bank height ratios. Throughout the comparison of several cribwall sites, the implication of this work is to demonstrate how to assess the fitness of similar soil bioengineering designs for application to diverse stream settings and to further validate their significance in stream restoration as designs that are multifunctional. Copyright © 2013 John Wiley & Sons, Ltd.     

Inter-tablet coating variability: Tablet residence time variability

This paper investigates inter-tablet coating variability, specifically, the variability of tablet residence times within the spray zone of a horizontal coating pan. Results from experiments, discrete element method (DEM) computer simulations, and an analytical model developed to describe the coating mass distribution are presented.The simulations indicate that the coefficient of variation of tablet residence times, and subsequently, of coating mass, decreases with time following a power law relation. The theoretical model demonstrates that the coefficient of variation of residence time for a randomly mixed tablet bed is inversely proportional to the square root of the number of coating “trials”. DEM simulations show that during each pan revolution, tablets in the spray zone remain in a quasi-segregated state from tablets located outside the spray zone for some time period termed Δt_seg. Increasing the pan's Froude number, the spray zone aspect ratio, and the tablet-tablet and tablet-pan friction coefficient all act to decrease Δt_seg, leading to more uniform residence times and less inter-tablet coating variability for a given operating time. The relationship between Δt_seg and tablet load is more complex due changes in bed dynamics. In addition to the variability studies, a model is developed that relates coating fraction, effective mass flow rate, Δt_seg, and the desired coating mass to the allowable fraction of tablets with a coating mass lying outside of a specified range of coating masses.