转换GPS高程的神经网络模型试验研究   总被引：10，自引：0，他引：10  

胡伍生  华锡生  鲍兴南 《测绘工程》2002,11(3):51-56

简要介绍了神经网络BP算法的基本结构和数学公式，并提出了转换GPS高程的神经网络模型-经改进五层BP网络结构。通过某工程实例，对五层BP网络结构的具体模型结构（如输入输出层设计，隐含层最佳节点数的选取等）进行了一些试验研究，得到了一些有工程实用价值的结论。  相似文献   

基于Pro/E的PDC钻头参数化设计   总被引：1，自引：0，他引：1  

刘刚 《煤田地质与勘探》2012,40(2):91-92

基于Pro/E (Pro/ENGINEER)的二次开发平台,以煤炭系统常用的胎体式内凹型PDC钻头为例,在系统分析钻头结构特点和主要参数相关性的基础上,建立了钻头结构设计各参数相关性技术体系实体参数化设计模型。通过设计Φ65 mm胎体式内凹PDC钻头,验证了该模型能够快速、准确地利用参数变化完成钻头体的三维及二维结构图设计,从而大大提高了设计效率和质量,为钻头参数化设计提供了参考。   相似文献   

Back Trajectory Analysis of Precipitation Chemistry in the Urban and Forest Areas of Istanbul,Turkey     

Levent Saylan  Hüseyin Toros  Orhan Sen 《洁净——土壤、空气、水》2009,37(2):132-135

There are many influences on precipitation chemistry and its variation. The transport paths of air masses before rainfall provide useful knowledge for evaluating and understanding the results of the analysis of the chemical compositions of precipitation. As a consequence, it is important to determine the variation of the chemical composition of rainwater by back trajectory analysis for estimating the source of the emissions. In this study, the rainwater samples were collected using specially designed collectors between November 1997 and June 1998 in the urban and forest areas of Istanbul. The rainwater samples were analyzed for major ion concentrations and pH. The volume‐weighed mean pH values were 5.8. The rainwater samples were classified to determine the source region of pollutants in rainwater using synoptic maps. In general, the results of the analysis on the chemical concentrations of precipitation during the measurement period showed that most of ions reached Istanbul from the directions of W‐SW, NW‐W, and NE‐N, respectively.  相似文献   

Assessment of slope stability in Ankara clay: a case study along E90 highway   总被引：1，自引：0，他引：1  

M.?B.?Teoman  T.?TopalEmail author  N.?S.?I??k 《Environmental Geology》2004,45(7):963-977

Some slope instability problems exist in Ankara clay along E90 highway. The purpose of this paper is to determine the mineralogical and geotechnical properties of soils, and to investigate the causes and mechanisms of three rotational landslides along a section of the highway. In order to accomplish these tasks, field studies, laboratory testing, back analyses, and limit equilibrium and finite difference analyses were performed. The landslides are formed within a soil consisting of clay and silt with a little sand and gravel. Slope stability analyses indicate that long-term stability of already failed slopes is critical. The failures are progressive, showing strain softening behavior with full saturation. Broken irrigation pipes existing near the landslides are found to be the main cause of sliding. Maintenance of the pipes, surface drainage, removal and replacement of the failed (slided) material are considered to be economical and practical solutions for the remediation of the slides.  相似文献   

Analysis of a highway embankment failure associated with the 1999 Düzce, Turkey earthquake     

B.S. Bak&#x;r  E. Ak&#x; 《Soil Dynamics and Earthquake Engineering》2005,25(3):251-260

An embankment slope on a major highway totally collapsed during 12 November 1999 Düzce earthquake (M_w=7.1) due to the intense near field ground motion. The slope had performed satisfactorily, without even minor deformations or cracks, during the İzmit earthquake (M_w=7.4), another major event that occurred 3 months before and was far field. Predominantly coarse-grained fill of the embankment exhibited typical non-brittle behavior during laboratory tests, implying that the prefailure shear strength would remain relatively unchanged. Stability and failure mechanism of the embankment slope were investigated through a series of static, pseudostatic and fully coupled non-linear dynamic analyses. While respective performances were correctly predicted by the pseudostatic method on a failure—no failure basis during the two earthquakes, the computed failure surface geometry did not conform to that observed. Fully coupled dynamic response analysis, on the other hand, predicted the failure mechanism and failure surface configuration in conformance with the post-failure observations. Computed displacements were generally less than those observed and critically dependent on the potential uncertainties.  相似文献   

塔里木盆地巴楚隆起北缘的吐木休克断裂与巴东断裂          下载免费PDF全文

周 慧陈永权  李洪辉李保华黄理力  刘亚雷龚洪林 文 磊 《地质科学》2021,56(1):1-018

吐木休克断裂位于塔里木盆地西部,巴楚隆起和阿瓦提凹陷之间,是一条大型基底卷入型冲断构造。走向NW‐SE,呈弧形向NEE凸出;倾向巴楚隆起。根据构造变形特征,断裂自NW向SE可以划分为4段。Ⅰ和Ⅲ段为简单基底卷入型冲断构造段;Ⅱ段发育背冲断层,与主干断层呈“y”字型剖面组合关系;Ⅳ段为基底卷入型楔状构造,主冲断层顶部出现一条向巴楚隆起逆冲的反冲断层。断裂上盘发育背斜,下盘有明显的“牵引构造”,显示吐木休克断裂可能是由吐木休克背斜北翼突破形成的,是一条褶皱相关断层。吐木休克断裂形成于中新世晚期至上新世初,持续演化至第四纪。断裂带上发育的上新世末—第四纪初正断层代表印度—亚洲碰撞脉动式远程效应的一个构造间歇期。吐木休克断裂东侧的巴东断裂是巴楚隆起与塔中隆起的过渡构造带,雏形形成于奥陶纪晚期—志留纪,晚新生代复活。  相似文献   

2013年4月20日四川芦山7.0级地震震源破裂特征   总被引：2，自引：0，他引：2       下载免费PDF全文

徐彦  邵文丽 《地球物理学报》2013,56(10):3396-3403

2013年4月20日四川芦山发生7.0级地震.本文运用反投影远震P波的方法研究了中心频率为1 Hz的芦山地震震源破裂特征.研究结果显示2013年芦山7.0级地震破裂长度约为20 km,震源破裂时间约为26 s.本文认为在芦山地震的开始阶段(0~4 s)震源的破裂是向震中位置两侧进行的.而芦山地震破裂的第二阶段(5~26 s)是单侧破裂.芦山地震最大能量释放区域位于震中以北.本文对比了运用相同方法研究的发生在同一断裂带上的2008年汶川地震震源破裂特征.发现2013年芦山地震和2008年汶川地震有三点相似之处,即,破裂主要沿北东走向的龙门山断裂带发展;最大能量释放区域没有位于震中;能量都是通过多次子事件来释放的,且第二次能量释放是最大能量释放.对比两次地震破裂区域,可以看出芦山地震的破裂区域是在2008年汶川地震破裂区域的西南端发展的.两次地震的破裂区域占了整个龙门山断裂带的三分之二.  相似文献