Assessment of seismic resistance of masonry structures including boundary conditions     

Emília Juhsov  Milan Hurk  Zbigniew Zembaty 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1193-1197

The paper is devoted to the investigation of seismic response of the masonry structure and describes experiences with modelling of boundary conditions during the test of large heavy model on 6DOF shaking table. The main aim of the research was how to increase dynamic resistance capacity of old masonry buildings including the medium and strong seismic effects. The results of theoretical and numerical analyses are compared including initial forecasting calculations made before any test started. The emphasis is given to the boundary conditions reached during the excitation of the large masonry model via shaking table. Strengthening and retrofitting procedures and their effects are discussed when special fibre mortar is used for repair and strengthening of masonry parts of structure.  相似文献   

Dynamic impedances of a weakly anelastic medium     

Zbigniew Sienkiewicz 《地震工程与结构动力学》1993,22(11):1009-1014

Approximate formulas are derived to evaluate in the frequency domain the dynamic impedances of a weakly anelastic medium based on its pure elastic behaviour. The correspondence principle is applied to the elastic solution of a boundary-value problem followed by the expansion of the anelastic solution in a Taylor series about the elastic state. Taking the magnitude of material damping into account (small damping) only the first two terms of the Taylor series have been used. The derivatives of first order in the expansion can be determined by the central difference approximation; this requires only the evaluation of differences between neighbouring elastic solutions.  相似文献   

Stochastic modeling of seismic surface rotations     

Alberto Castellani  Zbigniew Zembaty 《Natural Hazards》1994,10(1-2):181-191

In this paper, a stochastic analysis of surface rotations during earthquakes is presented. The surface motion is modeled by a spacetime random field. A method to obtain rotation based on direct differentiation of the random field is proposed with a reference to a second method based on wave decomposition. The first method leads to a spectral density of surface rotations in terms of point translation spectral density, coherence function and apparent waves velocity, while the second method formulates the rotational spectrum in terms of point translation spectral density and wave parameters. The advantages and disadvantages of both methods are discussed in detail.On leave from: Faculty of Civil Engineering, Technical University, ul. Katowicka 48, 45–951 Opole Poland.  相似文献   

Distribution of time lags between successive petroleum exploration activities     

Zbigniew ?ucki  Zbigniew Szkutnik 《Mathematical Geology》1990,22(5):523-556

Four time lags are studied: (1) drilling activity behind seismic activity; (2) oil and gas reserves discovered behind drilling activity; (3) oil and gas production behind reserves discovered; and (4) oil and gas production behind drilling activity. A ridge regression method is used to estimate the distributions of these lags for 50 countries and regions active in petroleum exploration. A complete review of obtained results is given as well as an interpretation of estimated models and failed ridge regressions. Five types of distributions have been found: decreasing monotonically, unimodal, bimodal, uniform, and increasing monotonically. The distributions allow estimating the capital freezing in the exploration process and assessing the resulting policy made by all companies active in a country. For example, the actual exploration history in Poland is analyzed with the use of distributed time-lag approach and net present-value concept. An overinvestment in drilling in comparison with petroleum infrastructure has been stated on the basis of the excessive lagging of production behind drilling activity. A direction of further lag studies is also suggested.  相似文献   

Fourth international symposium on land subsidence Houston,Texas, USA 12–15 May 1991     

Zbigniew Perski 《GeoJournal》1990,20(4):429-430

Fourth international symposium on land subsidence Houston, Texas, USA 12–15 May 1991  相似文献   

Damage reconstruction of 3D frames using genetic algorithms with Levenberg–Marquardt local search     

Seweryn Kokot  Zbigniew Zembaty 《Soil Dynamics and Earthquake Engineering》2009

A damage detection method based on harmonic structural vibrations has been applied to reconstruct typical damage patterns of reinforced concrete beams and frames vibrating in three dimensions. It has been shown that comparison of harmonic vibrations of damaged and intact structures makes it possible to formulate optimization criterion which can be solved effectively for large number of unknowns. The application of combined genetic algorithms and Levenberg–Marquardt local search enabled to reconstruct vectors of distinct stiffness distributions containing up to 32 elements with stiffness loss as low as 5% and with accuracy of 1%. To test the algorithm in more realistic environment of practical data acquisition, measuring noise with various levels has been added to the analyzed signal. Such a method of damage detection can be quite effective during post-earthquake assessment of civil engineering structures or if one wants to control the stiffness loss of a reinforced concrete structure after it was accidentally overloaded.  相似文献   

Preface     

Heiner Igel  Johana Brokesova  John Evans  Zbigniew Zembaty 《Journal of Seismology》2012,16(4):571-572

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Extension of EGNOS ionospheric correction coverage area     

Anna Swiatek  Iwona Stanislawska  Zbigniew Zbyszynski  Beata Dziak-Jankowska 《Acta Geophysica》2014,62(1):259-269

Ionosphere coverage is likely to be a driver for the EGNOS coverage area. Hence, a study considering a dedicated ionosphere algorithm to improve the ionosphere coverage area has been conducted. The logic of the study is the following: the accuracy of the GPS signal depends mainly on the total electron content (TEC). At two close points, TEC changes in time in a very similar way; these are region dependent variables. This correlation decreases with growing distance between the observation points and is anisotropic. Based on TEC variogram analysis, the specific algorithm has been developed. This specific algorithm is presented and discussed.  相似文献   

Statistics of Scalar Fields in the Atmospheric Boundary Layer Based on Large-eddy Simulations. Part 1: Free Convection     

Zbigniew?SorbjanEmail author 《Boundary-Layer Meteorology》2005,116(3):467-486

Convection in a quasi-steady, cloud-free, shear-free atmospheric boundary layer is investigated based on a large-eddy simulation model. The performed tests indicate that the characteristic (peak) values of statistical moments at the top of the mixed layer are proportional to the interfacial scales (from gradients of scalars in the interfacial layer). Based on this finding a parameterization is proposed for profiles of scalar variances. The parameterization employs two, semi-empirical similarity functions F_m(z/z_i) andF_i(z/z_i), multiplied by a combination of the mixed-layer scales and the interfacial scales.  相似文献   

On the origin of copper mineralization in the Kupferschiefer: a suIphur isotope study*     

Zbigniew Sawlowicz 《地学学报》1989,1(4):339-343

Sulphur isotopic compositions of copper and iron sulphides (dispersed and vein mineralization) from the Polish part of the Kupferschiefer were determined and compared with data from the literature. Most of the δ³⁴S values of sulphides range from about -40 to -25%, indicating sulphide precipitation during bacterial sulphate reduction in an open system which gradually chanes into a closed system. Sulphides from veins are usually enriched in ³⁴S compared to finely dispersed mineralization and were probably formed in a more closed system. Copper sulphides are generally a few permil heavier than pyrite. Coupled with detailed microscopical observations the isotope data suggest that the mineralization is either syngenetic or early diagenetic.  相似文献