市县测绘质量管理问题与对策     

邵立行  黄鑫雄 《现代测绘》2005,28(4):45-46,48

针对市县测绘质量管理方面存在的问题．从法律法规和监督等因素等进行了分析，认为有其相关法律法规完善、行业特点及社会的原因，需要认真分析探讨和提出解决该问题的对策。  相似文献   

Online test using displacement–force mixed control     

Peng Pan  Masayoshi Nakashima  Hiroshi Tomofuji 《地震工程与结构动力学》2005,34(8):869-888

This paper proposes an online test technique that employs mixed control of displacement and force. Two types of mixed control, ‘displacement–force combined control’ and ‘displacement–force switching control’ are proposed. In displacement–force combined control, one jack is operated by displacement‐control, and another is operated by force‐control. Validity of the combined control technique is demonstrated by a series of online tests applied to a base‐isolated structure subjected to horizontal and vertical ground motions simultaneously. The substructuring technique is employed in the tests, and the base‐isolation layer is tested, with the rest of the structure modeled in the computer. Displacement‐control and force‐control were adopted for simulating the horizontal and vertical response, respectively. Both displacement‐ and force‐control were implemented successfully despite interference between the two jacks. Earthquake responses of the base‐isolated structure involving the effects of varying axial forces on the horizontal hysteretic behavior of the base‐isolation layer were simulated. In the displacement–force switching control, the jack was operated by displacement‐control when the test specimen was flexible but switched to force‐control once the specimen became stiff. Validity of the switching control technique was also checked by a series of online tests applied to the base‐isolated structure subjected to vertical ground motions. Switching between displacement‐control and force‐control was achieved when the axial force applied to the base‐isolation layer changed from tension to compression or from compression to tension. Both the displacement‐ and force‐control were successful even with many rounds of switching. The test revealed that large accelerations occurred on the floor immediately above the base‐isolation layer at the instants when the axial force of the base‐isolation layer changed from tension to compression. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Online hybrid test by internet linkage of distributed test‐analysis domains     

Peng Pan  Motohide Tada  Masayoshi Nakashima 《地震工程与结构动力学》2005,34(11):1407-1425

Online hybrid tests (called the online tests), particularly when combined with substructuring techniques, are able to conduct large‐scale tests. An extension of this technique is to combine multiple loading tests conducted in remote locations and to integrate the tests with large numerical analysis codes. In this study, a new Internet online test system is developed in which a physical test is conducted in one place, the associated numerical analysis is performed in a remote location, and the two locations communicate over the Internet. To implement the system, a technique that links test and analysis domains located at different places is proposed, and an Internet data exchange interface is devised to allow data communication across Internet. A practical method that utilizes standard protocols implemented by operating systems for sharing files and folders is adopted to ensure stable and robust communication between remotely located servers that commonly protect themselves by strict firewalls. To combine the online test with a finite element program formulated in an incremental form and adopting an implicit integration scheme, a tangent stiffness prediction procedure is proposed. In this procedure, a tangent stiffness is estimated based on a few previous steps of experimental data. Using the system devised, tests on a base‐isolated structure were carried out. Here, the base‐isolation layer was taken as the tested part and tested in Kyoto University, Japan, and the superstructure was modelled by means of a finite element program and analysed in a computer located in Osaka University. A series of physical Internet online tests were carried out, with the integration time interval and the method of tangent stiffness prediction as the major parameters. The tests demonstrated that the Internet communication was very stable and robust, without malfunctions. The proposed method of stiffness prediction was effective even when the experimental hysteresis curves exhibited complex behaviour, thereby ensuring accurate simulation for the earthquake response of the entire structure. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

高等级公路软基硬壳层处理     

王亦贺  殷云波 《安徽地质》2005,15(3):217-219,226

根据高等级公路路基工程的软基硬壳层情况,讨论软基硬壳层的作用机理、对路基沉降和稳定的作用及在土压力上的反映.  相似文献   

流量过程线分割方法的分析探讨   总被引：8，自引：3，他引：8  

倪雅茜张文华  郭生练 《水文》2005,25(3):10-14,19

对流量过程线分割方法进行了深入的研究，讨论了对基流问题的认识，给出了较合理的基流定义；分析探讨了几种常见的流量过程线分割方法以及存在的问题，并对这些分割方法从物理成因和水文产汇流规律等方面进行了比较研究。  相似文献   

黄淮海平原地下水质量综合评价   总被引：1，自引：0，他引：1  

李政红  孙继朝  汪珊  郭秀红 《水文地质工程地质》2005,32(4):51-55

本文以北京、天津两市和河北、河南、山东、安徽、江苏五省新一轮地下水资源评价结果为依据,参照地下水质量标准[GB T14 848-93 ]和生活饮用水卫生标准[GB5 749-85 ] ,客观评价了黄淮海平原地下水综合质量状况,指出相对全国地下水综合质量现状而言,黄淮海平原地下水质量状况相对较差,自西而东地下水质量呈现出明显的水平分带规律。地下水污染多呈点状、线状。浅层地下水污染较突出,目前主要超标组分为总硬度、三氮、氟化物、氯化物、铁、锰等。  相似文献   

我国平原区土壤地球化学异常成因研究     

朱立新  马生明 《物探化探计算技术》2005,27(3):237-240

我国平原地区土壤地球化学异常普遍存在,但是目前对这些异常的成因缺乏系统认识。这里以长春和南京地区的Hg、Cd异常试验研究结果为例,利用元素相关关系法,对此进行了系统研究。结果表明,城镇及其周边地区的土壤地球化学异常,异常组分叠加量表现出表层累积型特点,此类异常的成因与人类活动有关。分布在河流沿岸的土壤地球化学异常,在垂向上,异常组分叠加量表现出了连续型分布特点,且异常组分含量主要受土壤物质组成的控制,此类异常是在河流沉积物自然沉积过程中形成的。  相似文献   

流量过程线分割的新方法--公式推导     

张文华郭生练  林凯荣 《水文》2005,25(5):11-15

针对现行流量过程线分割方法中存在着缺乏物理基础和客观的、科学的操作方法，以及其他的一些问题，提出了流量过程线的分割应遵循的三条基本原则，在此基础上提出流量过程线分割的新方法。该法通过流域的降雨资料和出口断面的流量资料，经推导得到Horton下渗能力曲线的三参数，并推导出地下净雨量在非饱和带运行时间公式和地下水汇流公式，从而对流域出口断面流量过程线进行分割。  相似文献   

RLS-BP人工神经网络算法在降水预报中的应用   总被引：2，自引：0，他引：2       下载免费PDF全文

余运河  胡邦辉  孔玉寿  谭言科  许云海 《气象科学》2004,24(3):333-341

RLS—BP是一种新发展起来、自动设置网络主要参数和具有快速收敛能力的人工神经网络模型，用预报对象动态消空处理加以改进，应用于大连地区短中期降水MOS预报，实施了其预报效果与普通BP网络对比的试验。结果表明，改进后的新模型既提高了降水的预报精度，又有良好的计算稳定性．并且适合推广应用于气温、能见度等诸多气象要素的预报和预测问题。  相似文献   

地质图机助制图相关的几个问题   总被引：7，自引：0，他引：7  

郑贵洲  王琪 《地质科技情报》1997,16(2):92-96

对地质图机助制图过程中地质信息数据库的建立、地质要素数字化、制图综合自动化、地质符号计算机管理４个方面作了详细论述。并重点提出了区调图幅数字化时的图层划分方案。  相似文献