边坡稳定性的神经网络预测研究   总被引：21，自引：0，他引：21  

贺可强  雷建和 《地质与勘探》2001,37(6):72-75

根据神经网络法的基本原理，结合38个实际边坡工程稳定实例，应用VB5．0可视化编程语言，建立了边坡稳定性的神经网络预测模型，并运用该模型对部分边坡工程的稳定性进行预测，预测结果与边坡实际稳定状态相吻合，从而表明了神经网络法在边坡稳定性预测中的有效性。  相似文献   

A displacement‐based seismic design procedure for RC buildings and comparison with EC8     

T. B. Panagiotakos  M. N. Fardis 《地震工程与结构动力学》2001,30(10):1439-1462

A procedure for displacement‐based seismic design (DBD) of reinforced concrete buildings is described and applied to a 4‐storey test structure. The essential elements of the design procedure are: (a) proportioning of members for gravity loads; (b) estimation of peak inelastic member deformation demands in the so‐designed structure due to the design (‘life‐safety’) earthquake; (c) revision of reinforcement and final detailing of members to meet these inelastic deformation demands; (d) capacity design of members and joints in shear. Additional but non‐essential steps between (a) and (b) are: (i) proportioning of members for the ULS against lateral loads, such as wind or a serviceability (‘immediate occupancy’) earthquake; and (ii) capacity design of columns in flexure at joints. Inelastic deformation demands in step (b) are estimated from an elastic analysis using secant‐to‐yield member stiffnesses. Empirical expressions for the deformation capacity of RC elements are used for the final proportioning of elements to meet the inelastic deformation demands. The procedure is applied to one side of a 4‐storey test structure that includes a coupled wall and a two‐bay frame. The other side is designed and detailed according to Eurocode 8. Major differences result in the reinforcement of the two sides, with significant savings on the DBD‐side. Pre‐test calculations show no major difference in the seismic performance of the two sides of the test structure. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Ground Based FTIR Measurements of Stratospheric Species from Harestua, Norway During Sesame and Comparison with Models     

B. Galle  J. Mellqvist  D.W. Arlander  I. Fløisand  M.P. Chipperfield  A.M. Lee 《Journal of Atmospheric Chemistry》1999,32(1):147-164

Vertical columns of HF, HCl, HNO3, ClONO2, N2O, ClO and COF2 were measured at Harestua, Norway (60.22° N, 10.75° E, Elevation 600 a.s.l.) beginning on 24 November 1994 and concluding on 1 May 1995 during Phase-III of the SESAME (Second European Stratospheric Arctic and Mid-latitude Experiment) measurement campaign. The vertical columns of HCl, HNO3 and ClONO2 measured on 81 days were compared with columns calculated by the 3-D Cambridge model SLIMCAT. In addition the results were also interpreted by comparison with a photochemical trajectory model. Good agreement was seen for HCl while the nitrogen compounds showed larger discrepancies, especially for ClONO2. Evidence for chlorine activation was seen with 65% reduction of the chlorine reservoirs (HCl + ClONO2) while the levels of ClO were greatly enhanced. Interpretation of the loss with the trajectory model indicated condensation of chlorine on PSCs. The vertical column ratio of COF2 and HF was measured to 0.21 outside the vortex and a factor of two lower inside. The recovery of ClONO2 was seen to be much faster than that of HCl in the early spring.  相似文献   

Mapping Soils,Vegetation, and Landforms: An Integrative Physical Geography Field Experience*   总被引：2，自引：0，他引：2  

Joseph P. Hupy  Stephen P. Aldrich  Randall J. Schaetzl  Pariwate Varnakovida  Eugenio Y. Arima  Juliegh R. Bookout  Narumon Wiangwang  Annalie L. Campos  Kevin P. McKnight 《The Professional geographer》2005,57(3):438-451

Students in a graduate seminar at Michigan State University produced a series of detailed vegetation, soils, and landform maps of a 1.5‐square‐mile (3.9 km²) study area in southwest Lower Michigan. The learning outcomes (maps) and skill development objectives (sampling strategies and various GIS applications) of this field‐intensive mapping experience were driven by the assumption that students learn and understand relationships among physical landscape variables better by mapping them than they would in a classroom‐based experience. The group‐based, problem‐solving format was also intended to foster collaboration and camaraderie. The study area lies within a complex, interlobate moraine. Fieldwork involved mapping in groups of two or three, as well as soil and vegetation sampling. Spatial data products assembled and used in the project included topographic maps, a digital elevation model (DEM), aerial photographs, and NRCS (National Resource Conservation Service) soil maps. Most of the soils are dry and sandy, with the main differentiating characteristic being the amount of, and depth to, subsurface clay bands (lamellae) or gravelly zones. The presettlement (early 1830s) vegetation of the area was oak forest, oak savanna, and black oak “barrens.” Upland sites currently support closed forests of white, black, and red oak, with a red maple, dogwood, and sassafras understory. Ecological data suggest that these oak forests will, barring major disturbance, become increasingly dominated by red maple. This group‐based, problem‐solving approach to physical geography education has several advantages over traditional classroom‐based teaching and could also be successfully applied in other, field‐related disciplines.  相似文献   

IMU/DGPS supported photogrammetry in China     

李英成  LI Xue-you  ZHAO Ji-cheng  GONG Xun-ping  TANG Liang 《测绘科学》2004,29(Z1):42-46

<正>People'sRepublicofChinaisoneofthemostrapidlydevelopingcountriesintheworldtoday.Thereisagreatdemandonhighlyactualandaccuratespatialinformationofthewholecountry,especiallyofWestChinawhichbecomesthefocusofdevelopmentoftheChinesegovernmentrightnowandinthenextyears,butwherestillnotenoughtopographicmapsareavailable.ThisraisesgreatchallengestothesurveyingandmappingcommunityinChina.FacingthenewchallengestheChineseAcademyofSurveyingandMapping(CASM)starteditspioneerworkearly2002toexplorenewtechniquesandtechnologiesavailabletodaytowardincreasingthemapproductivity.WithimportofaCCNS/AEROcontrolsysteminNovember2002,thefirstDGPS/IMU-basedphotogrammetricprojectinChinawassuccessfullyaccomplishedjointlybyCASM,theGermany-basedcompaniesIGIandTechedge.Twophotogrammetricblocksof1:4,000and1:20,000photoscales,respectively,wereflowninAnyang,China.Directgeoreferencingandintegratedsensororientationwereconducted.Resultsachievedwereprovenbyusinggroundcheckpointsandcomparedwiththoseofaerialtriangulation.Orthophotosgeneratedbasedondir  相似文献   

遥感信息不确定性研究   总被引：6，自引：1，他引：6  

葛咏  王劲峰  梁怡  马江洪 《遥感学报》2004,8(4):339-348

近年来遥感技术及遥感信息产业化发展迅猛 ,但遥感信息的不确定性制约着遥感信息的产品化和实用化的进一步发展。虽然 ,这一问题得到了国内外众多学者的关注 ,并提出和采用相关理论和方法进行分析 ,取得了相当的进展 ,但这些方法在分析遥感信息不确定性时忽略了一个重要的研究点 :遥感信息的不确定性传递机理。本文主要目标就是建立一套遥感信息不确定性的处理方法  相似文献   

日本国砂防工程中的数字测图     

杨正银 《四川测绘》2004,27(2):67-70

本文介绍了日本国砂防工程项目中的数字测图模式、产品特点及其实用意义。  相似文献   

Comparing the adequacy of alternative ground motion intensity measures for the estimation of structural responses     

Paolo Giovenale  C. Allin Cornell  Luis Esteva 《地震工程与结构动力学》2004,33(8):951-979

Practical methods for the probability‐based seismic assessment of structures make use of estimates of demands produced by earthquakes of different intensities. The uncertainties associated with these estimates are highly dependent on the variable adopted as the intensity measure (IM, e.g., PGA, spectral acceleration, etc.). This generates the need to compare the efficiency of an originally adopted IMwith that of a new candidate. This implies comparing the dispersion of the demand measure (DM, e.g., maximum interstorey drift ratio, ductility demand, etc.) conditional to each of the two IMs. In order to obtain the demand estimates in a conventional way, a full set of dynamic response analyses should be performed for each IM under scrutiny, i.e., multiple records scaled at several fixed values of each IM. The procedure developed here serves to accelerate this comparison avoiding the effort required to evaluate the dynamic responses of the structure for all the ground motion time histories considered every time that a new IM is adopted. For this purpose, use is made of available results of analyses performed for a different (i.e., the original) IM. Two methods are proposed: the direct method involves performing a regression of the results obtained from the original analyses, taking the candidate IM as the independent variable. The indirect method involves rebuilding the probability density function of the DM given a defined value of the candidate IM by means of the total probability theorem, using the results of the original analyses and certain data relating the two IMs. The proposed methods have been tested by application to several SDOF systems with different periods and different cyclic‐response backbone curves. The conditions affecting their approximation are explored, and some criteria to improve them are identified. The procedure can also be used to determine the optimum value of a parameter to be used in a parameter‐based IM. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Seismic behavior of asymmetric RC wall buildings: principles and new deformation‐based design method     

Alois Sommer  Hugo Bachmann 《地震工程与结构动力学》2005,34(2):101-124

The seismic design of multi‐story buildings asymmetric in plan yet regular in elevation and stiffened with ductile RC structural walls is addressed. A realistic modeling of the non‐linear ductile behavior of the RC walls is considered in combination with the characteristics of the dynamic torsional response of asymmetric buildings. Design criteria such as the determination of the system ductility, taking into account the location and ductility demand of the RC walls, the story‐drift demand at the softer (most displaced) edge of the building under the design earthquake, the allowable ductility (ultimate limit state) and the allowable story‐drift (performance goals) are discussed. The definition of an eccentricity of the earthquake‐equivalent lateral force is proposed and used to determine the effective displacement profile of the building yet not the strength distribution under the design earthquake. Furthermore, an appropriate procedure is proposed to calculate the fundamental frequency and the earthquake‐equivalent lateral force. A new deformation‐based seismic design method taking into account the characteristics of the dynamic torsional response, the ductility of the RC walls, the system ductility and the story‐drift at the softer (most displaced) edge of the building is presented and illustrated with an example of seismic design of a multi‐story asymmetric RC wall building. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Peak displacement demand of small to moderate magnitude earthquakes in stable continental regions     

Nelson Lam  Adrian Chandler 《地震工程与结构动力学》2005,34(9):1047-1072

A theoretical fault‐slip model has been developed for predicting the notional peak displacement demand (PDD) of earthquakes based on a limiting natural period of 5 s, for application in stable continental regions (SCRs). The developed theoretical expression is simple and robust. Importantly, it envelops predictions arising from a number of existing empirical and seismological (stochastic) models included in the comparison. The notional PDD prediction has been made initially for hard rock crustal conditions and at a reference source–site distance of 30 km. Factors have accordingly been introduced to correct for different distances and geological conditions in completing the PDD prediction model. Assuming displacement‐controlled behaviour, the predicted notional PDD may be compared with the displacement capacity of a structure, or component, for purposes of seismic stability assessment. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献