Investigations of nonlinear performances of implicit pseudodynamic algorithms     

張順益  黃裕鈞  宋裕祺 《地震工程与工程振动(英文版)》2006,5(2):257-266

Although it has been shown that the implementation of the HHT-α method can result in improved error propagation properties in pseudodynamic testing if the equation of motion is used instead of the difference equation to evaluate the next step acceleration, this paper proves that this method might lead to instability when used to solve a nonlinear system. Its unconditional stability is verified only for linear elastic systems, while for nonlinear systems, instability occurs as the step degree of convergence is less than 1. It is worth noting that the step degree of convergence can frequently be less than 1 in pseudodynamic testing, since a convergent solution is achieved only when the step degree of convergence is close to 1 regardless of whether its value is greater or less than 1. Therefore, the application of this scheme to pseudodynamic testing should be prohibited, since the possibility of instability might incorrectly destroy a specimen. Consequently, the implementation of the HHT-α method by using the difference equation to determine the next step acceleration is recommended for use in pseudodynamic testing.  相似文献   

存储检索系统监视信息采集技术分析   总被引：1，自引：0，他引：1  

常飚 《气象科技》2006,34(Z1):31-35

主要介绍国家级气象资料存储检索系统的监视分系统中监视信息采集功能的实现,对存储系统监视信息采集需求和方法进行了分析,介绍了包括调用系统命令和Java提取信息等方法,通过实际例子详细阐述了监视系统获取信息和存储信息的方式,并概括说明了目前投入业务运行的监视信息采集功能,最后对采集模块的改进提出建议。  相似文献   

Designing an optimal multivariate geostatistical groundwater quality monitoring network using factorial kriging and genetic algorithms   总被引：1，自引：0，他引：1  

Ming-Sheng Yeh  Yu-Pin Lin  Liang-Cheng Chang 《Environmental Geology》2006,50(1):101-121

The optimal selection of monitoring wells is a major task in designing an information-effective groundwater quality monitoring network which can provide sufficient and not redundant information of monitoring variables for delineating spatial distribution or variations of monitoring variables. This study develops a design approach for an optimal multivariate geostatistical groundwater quality network by proposing a network system to identify groundwater quality spatial variations by using factorial kriging with genetic algorithm. The proposed approach is applied in designing a groundwater quality monitoring network for nine variables (EC, TDS, Cl⁻, Na, Ca, Mg, SO ₄ ²⁻ , Mn and Fe) in the Pingtung Plain in Taiwan. The spatial structure results show that the variograms and cross-variograms of the nine variables can be modeled in two spatial structures: a Gaussian model with ranges 28.5 km and a spherical model with 40 km for short and long spatial scale variations, respectively. Moreover, the nine variables can be grouped into two major components for both short and long scales. The proposed optimal monitoring design model successfully obtains different optimal network systems for delineating spatial variations of the nine groundwater quality variables by using 20, 25 and 30 monitoring wells in both short scale (28.5 km) and long scale (40 km). Finally, the study confirms that the proposed model can design an optimal groundwater monitoring network that not only considers multiple groundwater quality variables but also monitors variations of monitoring variables at various spatial scales in the study area.  相似文献   

Estimating non‐linear site response by single period approximation     

Hing‐Ho Tsang  Adrian M. Chandler  Nelson T. K. Lam 《地震工程与结构动力学》2006,35(9):1053-1076

Site effects characterize the filtering mechanisms within the soil sedimentary layers overlying bedrock. In regions of high seismicity such as California where strong motion records are relatively abundant, site coefficients can be developed by regression of recorded ground shaking parameters. In regions of low‐to‐moderate seismicity or of high seismicity but with a paucity of recorded strong motion data, such empirical models cannot be obtained in the same way. This study describes the theoretical development of a simple, rational manual procedure to calculate site coefficients, based on a single period approximation (SPA), and to construct displacement response spectra (RSD) for soil sites. The proposed simplified model, which takes into account the non‐linear behaviour of soil that is dependent on the level of shaking, impedance contrast at the soil–bedrock interface and the plasticity of soil material, has been verified by comparison with results obtained from non‐linear shear wave analyses and data recorded during the 1994 Northridge earthquake. The proposed model is believed to be a convenient tool for calculating non‐linear site responses and constructing site‐specific response spectra, which has the potential of being incorporated into code provisions. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

地籍测量教学若干问题探讨   总被引：1，自引：0，他引：1  

何立恒  鲍其胜  常永青 《现代测绘》2006,29(6):45-47

地籍测量是测绘工程专业的专业课之一，也是土地资源管理专业的骨干课程。本文针对测绘工程专业，介绍该课程理论教学及实践教学内容与实施方案。对构建和完善地籍测量教学体系进行初步探讨和研究。  相似文献   

印尼8.9级地震前同一纬度"段"上东西两侧震兆信息讨论     

王泽皋  孙佩卿  乔子云  靳艳萍  马风霞  孙彦雪  常庆湘  张跃刚 《国际地震动态》2006,(8):36-39

根据观测,2004年12月26日印尼苏门答腊附近海域发生8.9级地震前同一纬度“段”上两侧MS≥6.0地震活动是具有时间和空间信息的,二者都可以作出回顾性时、空预测的结果。不仅如此,根据红山地震台的记录仍然可以得到“活动时段”预测的结果。最后强调了我们对大震预测的基本认识:大震前小震活动水平的涨落和分布情况是预测未来大震活动时间和空间的基础资料,而且都是这次大震前的“整体多维活动”。  相似文献   

Coexistence and inherence of diverse energy resources in the Ordos Basin, China     

常象春  王明镇  韩作振 《中国地球化学学报》2006,25(4):386-390

1 Introduction In recent years rapid economic developmentbadly needs energy resources. Exploration andexploitation of more kinds of energy resources shouldbe intensified to meet this need. According to presentliterature, oil/gas fields, coal fields as we…  相似文献   

支持向量机在大气污染预报中的应用研究   总被引：1，自引：1，他引：1  

常涛 《气象》2006,32(12):61-65

支持向量机是基于统计学习理论的新一代机器学习技术，其非线性回归预测性能优越于传统统计方法。利用前一天该污染物的日均浓度、前一天地面平均风速等7个预报因子建立了基于RBF核函数支持向量回归法的大气污染预报模型，并利用十重交叉验证和网格搜索法寻找模型最优参数。乌鲁木齐大气预报实例表明：支持向量机显示出小样本时预报精度较高和训练速度快的独特优势，为空气质量预报提供一种全新的模式。  相似文献   

边坡变形破坏模式识别系统的实现     

边亚东  张玉国  常利武 《岩土工程技术》2006,20(3):121-123,146

以岩体结构为最基本的控制因素,同时结合考虑岩性、结构面形态及边坡结构参数等因素实现了边坡变形破坏模式识别系统。系统将模式识别技术与专家系统有机结合,针对五种岩体类型边坡分别进行模式判断;具有与工程结合紧密、能获得定量结果、层次清晰及使用方便等优点。由本系统判断识别的破坏模式与实际破坏模式相符合,说明了系统的实用性和可行性。  相似文献   

甘肃北山地区煌斑岩的年代学和地球化学及其壳幔作用过程讨论   总被引：10，自引：10，他引：10  

刘畅赵泽辉  郭召杰 《岩石学报》2006,22(5):1294-1306

柳园地区下二叠统中发育多条煌斑岩脉，并且在空间上和二叠纪玄武岩、辉长岩和超镁铁岩关系密切。煌斑岩K-Ar、Ar-Ar定年测定表明岩脉侵入时间在220～240Ma之间。地球化学表现为富集大离子亲石元素和轻稀土，亏损高场强元素（Ta-Nb-Ti、Zr、Hf）的特征。Sr-Nd同位素以高的（^87Sr／^86Sr）i 0．708616～0．708744，较低的εNd（t）-3．89～-2．14为特征。Nb／Ta（16．16～19．14，相对于原始地幔的17．5）、Zr／Hf（42．14～43．95，相对于原始地幔的36．7）以及Ta．Nd．Ti的亏损，显示源区可能和早期俯冲洋壳或造山带根部拆沉组份脱水、富集流体交代岩石圈地幔有关。本区煌斑岩为二叠纪裂谷发展到后期，富集流体上涌，交代岩石圈地幔部分熔融，并沿断裂侵入的产物；是二叠纪开始的裂谷作用和火山活动晚期阶段产物。  相似文献