ArcGIS支持下的样本稀疏山区空间插值模拟探讨

样本稀疏地区空间插值法对区域化变量的精准管理具有重要意义。基于ArcGIS 90，在分析土壤属性空间分布特征的基础上，提出并构建了基于不同土壤类型的土壤特性空间预测模拟模型，对比了传统方法与改进方法空间插值精度，实现了数值插值在复杂地理环境区域的应用，得到以下结论：(1)基于经度、纬度、海拔高度及坡度等地理因子的土壤基础环境因子的空间预测模拟模型，突破以往只能描述土壤属性在水平方向变化的局限，较客观、合理地反映土壤属性随地理位置及海拔高度的立体变化特征；(2)基于不同土壤类型回归模型来增加样本点以推断评价指标在无取样地区的分布状况的处理方式具有一定的数学理论支撑，有效降低了插值误差，提高了评价精度，使评价结果更加接近现实。     

Most Influential Parameters for the Bed-Load Sediment Flux Equations Used in Alluvial Rivers1

Khorram, Saeed and Mustafa Ergil, 2010. Most Influential Parameters for the Bed-Load Sediment Flux Equations Used in Alluvial Rivers. Journal of the American Water Resources Association (JAWRA): 46(6):1065–1090. DOI: 10.1111/j.1752-1688.2010.00468.x Abstract: Problems of bed-load sediment transport equations in alluvial rivers are addressed in this study where user-friendly parameters were developed. To determine the influences of 300 parameters on the final result, 52 selected bed-load equations for noncohesive particles (sand and gravel separately) were gathered and individually investigated. The influences of discrepancies among the computed and measured datasets were obtained by sensitivity analysis through multilinear regression method. The most influential parameters for the bed-load sediment flux equations used to describe sand particles in alluvial rivers are: the gravitational power due to Shields’ parameter with an energy slope, the universal stream power due to critical Shields’ parameter with an energy slope, the Shields’ parameter ratio, the critical unit stream power, and the Shields’ parameter with energy slope. For gravel particles, the most influential parameters are: the universal stream power due to critical Shields’ parameter with an energy slope, the Shields’ parameter ratio, the gravitational power due to Shields’ parameter with an energy slope, the Shields’ parameter with an energy slope, and the Froude number of the channel. It is expected that researchers working in this field will be able to use these predicted parameters to generate new bed-load sediment flux equations that give results that more closely agree with the actual values measured in alluvial rivers.     

The explosion parameters of methanol under variable pressures and 423 K

The high-temperature and high-pressure methanol one-step oxidation has been the primary process for the mass production of dimethoxymethane. However, the risk of explosion for this process is still not properly defined. This paper presents new results from the experimental study on the explosion characteristics, including the explosion pressure and the explosion limits for methanol/air mixtures with a variable oxygen level, under an initial pressure between 0.3 MPa and 0.75 MPa and at the initial temperature of 423 K. The upper explosive limits were found to increase along with the initial pressure. If the limits for normal air are known, the oxygen effect on flammability is predictable from the thermal balance method. With a correlation for the pressure effect and a method for the oxygen effect, we can have the flammable range predictable.     

生态城市规划中人口预测--以昆山市生态城市规划为例

生态城市规划中人口预测对于经济发展预测、各个生态专项规划及制定建设决策都具有重要的借鉴意义。结合昆山生态城市规划实例,分析了昆山人口终极规模,并从人口总量、分布、素质和城市化等方面对昆山不同规划期进行人口预测。     

基于蒙特卡洛方法的着陆擦机尾风险预测

为解决对航班和机队着陆时擦机尾风险客观预测问题，基于飞行QAR数据和蒙特卡洛模拟方法，建立擦机尾风险预测模型，将某航空公司Boeing737-800机队的380套QAR数据作为样本数据，运用MATLAB编程进行5 000次模拟抽样试验，得到不同机队着陆时俯仰角的分布和擦机尾风险预测曲线。研究结果表明:当着陆俯仰角大于4.5°时，机队2擦机尾风险较大；运用蒙特卡洛模拟预测的飞机着陆俯仰角更为稳定和准确。该模型可进一步软件化，为航空公司的擦机尾超限事件管理提供可靠性指标参考，实现对飞行员操作风险的动态管理。     

Predicting the Planform Configuration of the Braided Toklat River,Alaska, With a Suite of Rule‐Based Models1

Abstract: An ensemble of rule‐based models was constructed to assess possible future braided river planform configurations for the Toklat River in Denali National Park and Preserve, Alaska. This approach combined an analysis of large‐scale influences on stability with several reduced‐complexity models to produce the predictions at a practical level for managers concerned about the persistence of bank erosion while acknowledging the great uncertainty in any landscape prediction. First, a model of confluence angles reproduced observed angles of a major confluence, but showed limited susceptibility to a major rearrangement of the channel planform downstream. Second, a probabilistic map of channel locations was created with a two‐parameter channel avulsion model. The predicted channel belt location was concentrated in the same area as the current channel belt. Finally, a suite of valley‐scale channel and braid plain characteristics were extracted from a light detection and ranging (LiDAR)‐derived surface. The characteristics demonstrated large‐scale stabilizing topographic influences on channel planform. The combination of independent analyses increased confidence in the conclusion that the Toklat River braided planform is a dynamically stable system due to large and persistent valley‐scale influences, and that a range of avulsive perturbations are likely to result in a relatively unchanged planform configuration in the short term.     

Introduction of geomechanical restoration method and its implications for reservoir assessment of unconventional oil-gas resource in China

New technologies are in urgent need of unconventional hydrocarbon exploration and development in China.This paper provides a brief introduction and analysis of a new three-dimensional(3D)geomechanical restoration method developed in recent years.After an in-depth discussion on the technical principle and specific characteristics of the fields,we designed a feasible workflow for two oil-gas fields with great unconventional oil-gas resource potentials in China(Weiyuan and Jiulongshan oil-gas fields of Sichuan).After discussing the major challenges and limitations of the new technology,we also suggest its research efforts and future application prospect It is shown that the new technology will be an effective method to facilitate the exploration and development of unconventional oil and gas resources in China.     

基于RBF神经网络的城市建成区面积预测研究——兼与BP神经网络和线性回归对比分析

城市建成区面积预测是城市研究的一个核心问题,其与城市经济社会之间表现为一种复杂的非线性关系,传统的方法模型难以精确预测。作为一种较新的人工神经网络模型,RBF神经网络能以任意精度全局逼近任意非线性关系,表现出了极强的处理复杂非线性系统的能力。以合肥市建成区面积预测为例,构建了基于RBF网络的预测模型,作为对比,同时用BP神经网络、一元线性回归和多元线性回归模型进行了预测。预测结果的综合分析表明,在预测精度上,RBF网络＞BP网络＞多元线性回归模型＞一元线性回归模型。研究显示,RBF网络能为城市建成区面积预测提供一种新思路和新方法,进而可为城市土地利用及其规划制定提供科学的决策依据     

基于灰色支持向量机的湿天然气集输管道腐蚀研究

湿天然气集输管道系统运行时间长,管道腐蚀严重,失效泄漏事故频发,其系统风险评价面临诸多问题,因而研究其腐蚀率预测有重要意义。基于灰色支持向量机(GSVM)方法,综合考虑管道材质及其各种影响因素,对其进行灰色相关分析,并根据结果选取有较高相关度的影响因子作为输入变量,将腐蚀率作为目标输出函数,建立湿天然气集输管道腐蚀预测模型。并通过实证分析比较,发现用该模型计算出的管道腐蚀率平均相对误差较小,其预测结果与实际值吻合程度较高,使预测精度得到提高。