Modeling long term lake variations by physically based stochastic dynamic models     

V. E. Privalsky 《Stochastic Environmental Research and Risk Assessment (SERRA)》1988,2(4):303-315

Several physically based stochastic dynamic models (SDM) are described including year-to-year variations of water volume in terminal and non-terminal lakes, streamflow of lake-fed rivers, and salinity of an inland sea (the Sea of Azov). All of these models are based upon the SDM of water volume of terminal lakes developed by Kritzky and Menkel in 1946 in co-operation with Kolomogorov. Explicit formulae are derived for second order statistical moments of the output processes, including variance, correlation function, spectra, etc., under the assumption that the forcing functions from stationary random sequences. The least-squares prediction problem is solved for both stationary and non-stationary cases. Some of the processes are shown to possess high statistical predictability. Actual predictions are compared with independent observations. Problems for further study are stated.  相似文献   

岩浆型铜镍硫化物矿床地质概念模型   总被引：4，自引：1，他引：4  

胡旺亮 《地球科学》1991,16(3):249-256

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泥湾门大桥浅海大直径嵌岩桩施工技术          下载免费PDF全文

柴云来 《探矿工程》1994,(3):28-29,31

介绍了在浅海施工直径２．２０ｍ嵌岩桩的技术问题。包括平台的搭设，用刮刀钻头与牙轮钻头钻进克取硬岩一次成孔工艺，利用冲洗液平衡原理处理浅海钻进护简断裂的成孔方法，改进浇灌清孔流程，保证浇灌质量。  相似文献   

WH-1型电镀金刚石钻头的研制及其在坚硬、致密和弱研磨性地层中的应用     

李大佛 《地球科学》1985,(3)

本文阐述了电镀金刚石孕镶钻头的研制方法和原理。此种钻头适用于坚硬、致密、弱研磨性(即所谓打滑)地层的钻进。攻克“打滑地层”的途径是:(1)降低钻头胎体耐磨性,促使金刚石出刃;(2)改变钻头底唇形状,提高金刚石破碎岩石的比压,增多孔底破碎岩石的自由面,使之易于破碎岩石。从4个钻探队、39个钻头的生产试验结果来看,上述研制工作既合理又有成效。  相似文献   

电镀金刚石钻头镀层与钢体结合强度研究     

潘秉锁  杨洋  杨凯华 《地质与勘探》2005,41(3):92-94

采用直接剪切试验,研究了稀土添加量、镀液pH值和电流密度对结合强度的影响;并结合试样断口的扫描电镜分析结果,对镀层的破坏形式进行了讨论.  相似文献   

打滑地层新型孕镶金刚石钻头   总被引：7，自引：0，他引：7  

罗爱云  段隆臣  王伟雄  田永常 《地质科技情报》2007,26(1):109-112

在分析打滑地层特点的基础上,指出了钻进该地层所存在的问题,提出了用于打滑地层钻进的新型孕镶金刚石钻头的设计思路,在钻头工作层中采用主、辅两种磨料,并对这两种磨料的工作机理、处理工艺以及该新型钻头的制造进行了阐述.钻头的室内钻进试验结果表明:在钻进极坚硬致密的锆刚玉时,相对于普通金刚石钻头,新型孕镶金刚石钻头的钻进时效提高1.93倍,平均磨损量增加38%,具有高时效、相对寿命长的优点,是打滑地层钻进的理想钻头.  相似文献   

Simulated effect of a forest road on near‐surface hydrologic response: redux     

Benjamin B. Mirus  Brian A. Ebel  Keith Loague  Beverley C. Wemple 《地球表面变化过程与地形》2007,32(1):126-142

In the work reported here the comprehensive physics‐based Integrated Hydrology Model (InHM) was employed to conduct both three‐ and two‐dimensional (3D and 2D) hydrologic‐response simulations for the small upland catchment known as C3 (located within the H. J. Andrews Experimental Forest in Oregon). Results from the 3D simulations for the steep unchannelled C3 (i) identify subsurface stormflow as the dominant hydrologic‐response mechanism and (ii) show the effect of the down‐gradient forest road on both the surface and subsurface flow systems. Comparison of the 3D results with the 2D results clearly illustrates the importance of convergent subsurface flow (e.g. greater pore‐water pressures in the hollow of the catchment for the 3D scenario). A simple infinite‐slope model, driven by subsurface pore‐water pressures generated from the 3D and 2D hydrologic‐response simulations, was employed to estimate slope stability along the long‐profile of the C3 hollow axis. As expected, the likelihood of slope failure is underestimated for the lower pore pressures from the 2D hydrologic‐response simulation compared, in a relative sense, to the higher pore pressures from the 3D hydrologic response simulation. The effort reported herein provides a firm quantitative foundation for generalizing the effects that forest roads can have on near‐surface hydrologic response and slope stability at the catchment scale. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Energy demands for seismic design against low‐cycle fatigue     

Amador Teran‐Gilmore  James O. Jirsa 《地震工程与结构动力学》2007,36(3):383-404

A seismic design procedure that does not take into account the maximum and cumulative plastic deformation demands that a structure is likely to undergo during severe ground motion could lead to unsatisfactory performance. In spite of this, current design procedures do not take into account explicitly the effect of low‐cycle fatigue. Based on the high correlation that exists between the strength reduction factor and the energy demand in earthquake‐resistant structures, simple procedures can be formulated to estimate the cumulative plastic deformation demands for design purposes. Several issues should be addressed during the use of plastic energy within a practical performance‐based seismic design methodology. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Expected loss‐based alarm threshold set for earthquake early warning systems     

Iunio Iervolino  Massimiliano Giorgio  Gaetano Manfredi 《地震工程与结构动力学》2007,36(9):1151-1168

Earthquake early warning systems (EEWS) seem to have potential as tools for real‐time seismic risk management and mitigation. In fact, although the evacuation of buildings requires warning time not available in many urbanized areas threatened by seismic hazard, they may still be used for the real‐time protection of critical facilities using automatic systems in order to reduce the losses subsequent to a catastrophic event. This is possible due to the real‐time seismology, which consists of methods and procedures for the rapid estimation of earthquake features, as magnitude and location, based on measurements made on the first seconds of the P‐waves. An earthquake engineering application of earthquake early warning (EEW) may be intended as a system able to issue the alarm, if some recorded parameter exceeds a given threshold, to activate risk mitigation actions before the quake strikes at a site of interest. Feasibility analysis and design of such EEWS require the assessment of the expected loss reduction due to the security action and set of the alarm threshold. In this paper a procedure to carry out these tasks in the performance‐based earthquake engineering probabilistic framework is proposed. A merely illustrative example refers to a simple structure assumed to be a classroom. Structural damage and non‐structural collapses are considered; the security action is to shelter occupants below the desks. The cost due to a false alarm is assumed to be related to the interruption of didactic activities. Results show how the comparison of the expected losses, for the alarm‐issuance and non‐issuance cases, allows setting the alarm threshold on a quantitative and consistent basis, and how it may be a tool for the design of engineering applications of EEW. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

A comparison of single‐run pushover analysis techniques for seismic assessment of bridges     

R. Pinho  C. Casarotti  S. Antoniou 《地震工程与结构动力学》2007,36(10):1347-1362

Traditional pushover analysis is performed subjecting the structure to monotonically increasing lateral forces with invariant distribution until a target displacement is reached; both the force distribution and target displacement are hence based on the assumption that the response is controlled by a fundamental mode, that remains unchanged throughout. However, such invariant force distributions cannot account for the redistribution of inertia forces caused by structural yielding and the associated changes in the vibration properties, including the increase of higher‐mode participation. In order to overcome such drawbacks, but still keep the simplicity of using single‐run pushover analysis, as opposed to multiple‐analyses schemes, adaptive pushover techniques have recently been proposed. In order to investigate the effectiveness of such new pushover schemes in assessing bridges subjected to seismic action, so far object of only limited scrutiny, an analytical parametric study, conducted on a suite of continuous multi‐span bridges, is carried out. The study seems to show that, with respect to conventional pushover methods, these novel single‐run approaches can lead to the attainment of improved predictions. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献