二三维联动的虚拟校园设计与实现

传统的2维地理信息系统技术成熟但缺乏3维可视化和分析的能力,而目前的3维地理信息系统发展可拥有3维可视化分析能力,然而还缺少2维地理信息系统的便捷。以二三维联动为开发思路的地理信息系统能够解决这对矛盾。本文基于二三维联动GIS的设计方案,以虚拟校园设计与实现为应用实例,利用ArcEngine（AE）实现二三维联动GIS系统的开发设计,对GIS系统的开发做出了一种新的、有益的尝试。     

三峡库区高切坡致灾因素及防护对策——以重庆市万州区为例

三峡库区百万移民的搬迁建设导致大量高切坡的形成。未及时治理或治理不当的高切坡,不同程度地发生破坏,影响了人们的正常生活,甚至引发了地质灾害。因此,科学认识及治理高切坡十分必要。重庆市万州区高切坡主要有风化及差异风化、崩塌和土体滑塌等破坏形式。影响破坏的因素主要为工程地质条件、气候及时间效应。针对高切坡不同的破坏形式,以安全、经济及环境和谐的人文理念作为设计指导思想,充分论证了高切坡的防护方案,即：削坡、排水以及格构防护较适合万州区高切坡的防护。这些措施,既能很好地解决高切坡的防护问题,又能兼顾环保、降低造价。研究结果可以作为三峡地区高切坡类地质灾害防护设计的参考。也可为其它流域类似问题借鉴。     

含盐量对松嫩平原碳酸盐渍土抗剪强度的影响

松嫩平原分布着大量的碳酸盐渍土,其不良的工程性质给穿越其中的道路质量造成不同程度的影响。由于盐渍土所含易溶盐成分主要为碳酸氢钠,该研究通过向碳酸盐渍土内加入碳酸氢钠制备不同含盐量的盐渍土,进行室内直剪试验。试验表明：随着含盐量的增加土的粘聚力减小,内摩擦角有先减小后变大的趋势;随着含水量的增加,土的含盐量越高,土的粘聚力减小越明显。易溶盐在土中的状态形式是影响其抗剪强度参数变化的一个重要原因。     

GM（1，1）动态模型在吴江市地下水水位预测中的应用

以吴江市地下水水位预测为例,详细阐述了地下水水位时间序列的GM（1,1）动态模型的原理和建立过程,并根据模型的预测值和实测值,对模型的精度进行了检验,结果表明,模型的预测精度达到了99．27％,等级属于Ⅰ级,具有实际的应用价值,为地下水资源的科学管理提供了依据。     

Calibration of an oscillating nozzle‐type rainfall simulator

Nozzle‐type rainfall simulators are commonly used in hydrologic and soil erosion research. Simulated rainfall intensity, originating from the nozzle, increases as the distance between the point of measurement and the source is decreased. Hence, rainfall measured using rain gauges would systematically overestimate the rainfall received at the ground level. A simple model was developed to adjust rainfall measured anywhere under the simulator to plot‐wide average rainfall at the ground level. Nozzle height, plot width, gauge diameter and height, and gauge location are required to compute this adjustment factor. Results from 15 runs at different rain intensities and durations, and with different rain gauge layouts, showed that a simple average of measured rain would overestimate the plot‐wide rain by about 20 per cent. Using the adjustment factor to convert measured rainfall for individual gauges before averaging improved the estimate of plot‐wide rainfall considerably. For the 15 runs considered, overall discrepancy between actual and measured rain is reduced to less than 1 per cent with a standard error of 0·97 mm. This model can be easily tested in the ?eld by comparing rainfall depths of different sized gauges. With the adjustment factor they should all give very similar values. Copyright © 2003 John Wiley & Sons, Ltd.     

τ-P域地震资料三维叠前深度偏移及其实用算法

本文提出了在τ-P域实现三维叠前深度偏移的计算方法，该方法把地震道集由时-空域变换到τ-P域，然后对共P数据体进行相移或相移加插值偏移，将偏移后的各共P数据体叠加得到叠前深度偏移结果．该算法能够实现陡倾地层的正确归位，降低偏移处理维数，减少计算机内存需求，易于并行处理，但是计算量和所花费的计算机时间仍然很大．为此我们又提出了针对目的层的分时（层）偏移方法，由于只考虑目的层，可节省大量的计算时间．文中以二维实际地震资料及三维数值模型资料的处理说明了上述方法的可行性与有效性．     

Fundamental study on the response characteristics of drivers during an earthquake based on driving simulator experiments

After the 1995 Kobe earthquake, the expressway structures in Japan were retrofitted and they will not now be seriously damaged under a certain level of strong earthquake motion. However, the stability of a moving vehicle has not been investigated yet. It has been reported that drivers feel seismically induced vibrations, especially in the transverse direction of vehicles. Owing to this phenomenon, drivers have some difficulty in controlling the vehicles during strong shaking. For further safety promotion of the expressway networks, it is important to understand the drivers' reactions to seismic motion. The present authors have performed a series of seismic response analyses of a moving vehicle to investigate its response characteristics based on numerical simulation. However, the responses of the driver were not considered in the simulation process. In order to investigate the drivers' reactions during an earthquake, a series of virtual tests were conducted using a driving simulator. This driving simulator has six servomotor‐powered electric actuators that control its motions. Several types of tests were carried out for different examinees to investigate drivers' responses while controlling the simulator under seismic motion. The results of this study showed that a larger response time lag to strong shaking and over turning of the steering wheel may shift the vehicle into the next lane. According to this finding, trafficaccidents could possibly occur under strong ground shaking in the case of heavy traffic. Copyright © 2004 John Wiley & Sons, Ltd.     

毛乌素沙地植被水分利用效率的时空格局

水分利用效率（WUE）是衡量生态系统碳水循环耦合程度的重要指标,明晰其动态变化规律有助于判断区域植被生态建设是否与当地的自然条件相适应。利用基于CASA（Carnegie-Ames-Stanford Approach）模型得到的植被净初级生产力（NPP）数据和MODIS系列产品中的蒸散发（ET）数据,估算了2001—2016年毛乌素沙地植被的WUE,并探讨了其时空演变特征及与气象因子的关系。结果显示：（1）WUE的多年平均值为0.62 gC·mm^-1·m^-2,空间上自东向西递减,在不同植被类型间表现为栽培植物>灌丛>草甸>草原>荒漠;（2）WUE以0.009 gC·mm^-1·m^-2·a^-1的速率上升,东部地区变化尤为显著,NPP的快速增长是WUE呈增加趋势的主要原因;（3）WUE与各气象因子的相关程度由大至小依次为太阳辐射、降水量、风速和气温,分布在西部地区的荒漠植被WUE受气象因子影响最小。经过一系列生态建设工程的治理,毛乌素沙地大部分地区自2001年以来NPP和WUE均呈增加趋势,即生态系统在变“绿”的同时还实现了水分的高效利用,有利于当地生态环境的健康发展;但在水热条件较差的中西部地区,新建设的植被生长缓慢且导致蒸散发产生强烈变化,使WUE呈减少趋势,暴露出植被建设规模与水资源承载能力不匹配的问题,需引起格外重视。     

青藏高原西部阿汝冰芯记录的近100 a气温变化研究

以2017年9月钻取自青藏高原西部阿汝冰崩区长度55.29 m的阿汝冰芯为研究对象,通过冰芯δ18O记录与Nye模型重建了冰芯上部17.87 m的时间序列是1917—2016年.结合冰芯邻近的改则、狮泉河气象站1973—2016年夏季平均气温数据,通过相关性分析及线性回归法、Mann-Kendall(M-K)检验分析,...     

基于动态极坐标参数化的遥感影像匹配方法

图像匹配作为三维重建至关重要的环节,其精度直接影响了平差优化、正射校正等模块的精度。对于城镇、农场等特征密集型区域,特征距离小,相似性强,易于匹配图像;而针对草地、沙漠等特征不明显区域,特征距离大,如果使用特征点匹配的方法,严格阈值下难以获得足够数量的匹配对,放宽阈值又将引入较多误匹配对,这也是导致稀疏点云不够均匀的原因之一。在此场景下,本文提出了基于动态极坐标参数化的无人机正视影像匹配算法,首先对图像做极坐标参数变化,采用动态策略解决极轴方向采样不均匀的问题,使用最小二乘法对得到的极坐标影像对做位移方向上的匹配,匹配后得到的旋转量和平移量,将该结果和SIFT算法的结果做比较。本文设计了2组实验,即参数已知的解算实验和参数未知的解算实验,且每组实验进行3次。在同等配置的计算机上,对两张7360像素×5400像素,32位的影像,本文方法的位姿解算时间相比SIFT的时间减少约57%,二者求得的位姿差通常小于1%。结论表明二者的结果在精度上表现相当,在时间上明显优于SIFT算法,具有实际的应用价值。