Wojciech Krzemi&#;ski 《Journal of Geodesy》1981,55(2):I

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Random vibrations of the baltic drilling platform subjected to wind loads and water waves     

Wojciech Jesie&#x; 《地震工程与结构动力学》1987,15(5):595-617

This paper presents random vibrations of the Baltic drilling platform subjected to water waves and wind loads. The platform structure is discretized by the finite element method. Linear beam or truss elements can be used. The structure parameters (i.e. mass, damping and stiffness) are assumed as deterministic. Soil is modelled as an elastic half-space that possesses deterministic or random parameters. Soil–structure interaction is idealized as a system of spring–dashpot elements connecting the structure and subsoil. The parameters of these elements can be random or deterministic. The sea surface is described by the one-dimensional wave spectrum that was proposed by Striekalov and Massel²⁴ for inland seas. It is suitable for the Baltic Sea. The wind velocity is described by the well-known Davenport spectrum. The water and wind loads are treated as stationary ergodic processes. Gaussian distributions and zero means of these processes are assumed. In addition to this, waves and wind loads are considered as independent. Such an assumption corresponds to the situation when the storm sea is fully developed. A frequency-domain random-vibration approach is utilized to obtain the dynamic response of the platform. The equations of motion of the problem were solved using modal reduction. The numerical calculations were made with a specially written computer program. From the results obtained, it is concluded that the wind influence on the response of the platform can be neglected. If random parameters are assumed for the subsoil, then the response of the system describes in a more realistic way the dynamic behaviour of the platform. The velocity coupling due to soil and hydrodynamical damping is negligible. This paper is a condensation of the author's Ph.D. thesis presented at the Technical University of Gdańsk in July 1985.  相似文献   

“All transport problems are essentially mathematical”: The uneven resonance of academic transport and mobility knowledge in Brussels     

Wojciech Kębłowski  David Bassens 《Urban geography》2018,39(3):413-437

This paper presents an inquiry into the capacity of transport and mobility studies to critically engage with contemporary policies. Drawing on the conceptualization of circuits of knowledge, the paper scrutinizes the extent to which transport policy agendas are framed around various approaches within academia. An extensive literature review reveals that the academic field of transport and mobility is organized around a hegemonic core of “neoclassical” and “sustainable” approaches. Meanwhile, a critique of these dominant approaches is emerging in an attempt to (re)embed mobility issues in urban political economy. This threefold knowledge typology visibly resonates within transport policy agendas in Brussels, where we detect a growth-oriented and largely depoliticized dual hegemony of neoclassical and sustainable narratives, with critical academic voices rarely entering official agendas. The paper concludes with a reflection on the difficulties, yet also the need to mobilize critical academic knowledge in the field of transport and mobility.  相似文献   

Long-term forest cover changes,within an agricultural region,in relation to environmental variables,Lubelskie province,Eastern Poland     

Wojciech Zgłobicki  Leszek Gawrysiak  Bogusława Baran-Zgłobicka  Małgorzata Telecka 《Environmental Earth Sciences》2016,75(20):1373

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Investigation of Water-Exchange Processes in the Caspian Sea on the Basis of Isotopic and Oceanographic Data     

Ferronsky  V. I.  Brezgunov  V. S.  Vlasova  L. S.  Polyakov  V. A.  Froehlich  K.  Rozansky  K. 《Water Resources》2003,30(1):10-22

Results of the sampling for temperature, salinity, and isotopic composition of water masses that was performed in the Caspian Sea at deepwater stations along a meridional profile during the international expeditions of 1994–1996 are presented. The water-exchange processes in this basin are analyzed on the basis of the distributions of salinity and isotopes in space and time.  相似文献   

The dynamics of rupture in porous media     

Wojciech Stopiński  Aleksandr V. Ponomaryov  Vladimir Loś 《Pure and Applied Geophysics》1991,136(1):29-47

This paper presents a laboratory investigation of electric resistivity parameter for samples subject to loading in automatic press of INOVA type. The procedure of automatic quasi-continuous measurements of resistivity is briefly outlined. The distribution of mini-electrodes within the sample is described. Also shown is the manner in which reliability can be improved by increasing the repetition of resistivity measurements (every 7–16 s).  相似文献   

Assessment of heavy metal contamination levels of street dust in the city of Lublin,E Poland     

Wojciech Zgłobicki  Małgorzata Telecka  Sebastian Skupiński  Aneta Pasierbińska  Marcin Kozieł 《Environmental Earth Sciences》2018,77(23):774

Heavy metals are constantly emitted into the environment and pose a major threat to human health, particularly in urban areas. The threat is linked to the presence of Cd, Cr, Cu, Ni, Pb, and Zn in street dust, which consists of mineral and organic particles originating from the soil, industrial emitters, motor vehicles, and fuel consumption. The study objective was to determine the level of street dust contamination with trace metals in Lublin and to indicate their potential sources of origin. The analyses were carried out with an energy-dispersive X-ray fluorescence spectrometer. The sampling sites (49) were located within the city streets characterised by varying intensity of motor traffic. The following mean content values and their variation (SD) were determined: Cd: 5.1?±?1.7 mg kg^?1, Cr: 86.4?±?23.3 mg kg^?1, Cu: 81.6?±?69.2 mg kg^?1, Ni: 16.5?±?3.9 mg kg^?1, Pb: 44.1?±?16.4 mg kg^?1, and Zn: 241.1?±?94.6 mg kg^?1. The level of pollution was assessed with several widely used geochemical indices (geoaccumulation index, enrichment factor, pollution index, index of ecological risk, and potential ecological risk index). For most of the indices, the mean (median) values are arranged in the following manner: Zn?>?Cu(or Cd)?>?Pb?>?Ni?>?Cr. In general, street dust in Lublin does not show pollution with Cr, Ni, and Pb. I_geo and EF indices show moderate levels for Cu, Cd, and Zn; their presence in street dust is linked with anthropogenic factors (motor traffic). A significant threat is posed by Cd, and more than half of the samples show considerable pollution with cadmium (median for the index of ecological risk: 151). The spatial pattern of indices and the results of statistical analyses (CA, PCA) indicate three groups of elements: (1) Cr and Ni: natural origin; (2) Pb: mixed origin; and (3) Cd, Cu, and Zn: anthropogenic origin (mainly motor vehicle traffic). Higher content values for metals of anthropogenic origin in street dust indicate that it is a source of pollution of soil and air in the city.  相似文献   

Gilbert‐type deltas recording short‐term base‐level changes: Delta‐brink morphodynamics and related foreset facies          下载免费PDF全文

Katarina Gobo  Massimiliano Ghinassi  Wojciech Nemec 《Sedimentology》2015,62(7):1923-1949

Gilbert‐type deltas are sensitive recorders of short‐term base‐level changes, but the delta‐front record of a base‐level rise tends to be erased by fluvial erosion during a subsequent base‐level fall, which renders the bulk record of base‐level changes difficult to decipher from the delta‐front deposits. The present detailed study of three large Pleistocene Gilbert‐type deltas uplifted on the southern coast of the Gulf of Corinth, Greece, indicates a genetic link between the delta‐front morphodynamic responses to base‐level changes and the delta‐slope sedimentation processes. Sigmoidal delta‐brink architecture signifies a base‐level rise and is accompanied by a debrite‐dominated assemblage of delta foreset deposits, thought to form when the aggrading delta front stores sediment and undergoes discrete gravitational collapses. Oblique delta‐brink architecture tends to be accompanied by a turbidite‐dominated assemblage of foreset deposits, which are thought to form when the delta‐front accommodation decreases and the sediment carried by hyperpycnal effluent bypasses the front. This primary signal of the system response to base‐level changes combines further with the secondary ‘noise’ of delta autogenic variation and possible allogenic fluctuations in fluvial discharge due to regional climatic conditions. Nevertheless, the evidence suggests that the facies trends of delta foreset deposits may be used to decipher the delta ‘hidden’ record of base‐level changes obliterated by fluvial topset erosion. Early‐stage bayhead deltas may be an exception from the hypothetical model, because their narrow front tends to be swept by river floods irrespective of base‐level behaviour and their subaqueous slope deposits are thus mainly turbidites.  相似文献   

Structural,metamorphic and geochronological record in the Goszów quartzites of the Orlica–Śnieżnik Dome (SW Poland): implications for the polyphase Variscan tectonometamorphism of the Saxothuringian terrane     

Miros&#x;aw Jastrz&#x;bski  Bartosz Budzy&#x;  Wojciech Stawikowski 《Geological Journal》2016,51(3):455-479

This integrated study on the pressure–temperature–deformation‐time record of the Goszów light quartzites from the Młynowiec–Stronie Group (Sudety Mts., SW Poland) provides new data that improve our understanding of the structure and geodynamic development of the Orlica–Śnieżnik Dome (OSD) as a Gondwana‐derived unit involved in the formation of the Variscan orogen. The structural and metamorphic record of the Goszów light quartzites, when compared to the under‐ and overlying rock formations, indicates that the whole Młynowiec–Stronie Group in the eastern part of the Saxothuringian terrane functioned as a single, integral lithotectonic unit with no visible structural or metamorphic discontinuities. The sequence of structures and thermodynamic modelling indicate that the light quartzites underwent the same polyphase tectonometamorphic evolution as the adjacent rocks belonging to the Młynowiec–Stronie Group. The development of tight, N–S‐trending folds and axial penetrative metamorphic foliation was related to metamorphic progression from 500 °C to 640 °C at 6–7 kbar. Subsequently, under the retrogressive conditions below 540 °C, the foliation was reactivated as a result of subsequent N–S‐directed ductile shearing and extension. Therefore, the study of the light quartzites exemplifies the penetrative structures in the OSD, and the metamorphic foliation and N–S‐trending lineation are composite structures. The monazite metamorphic ages of ca. 364 Ma and 335 Ma may be related to the approximately E–W‐ and N–S‐oriented tectonic movements, respectively, which occurred during the amalgamation of the Saxothuringian terrane with Brunovistulia. In contrast, the previously unknown early Palaeozoic monazite age of ca. 494 Ma is interpreted as the protolith age of the light quartzites. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Phenomenological fractional stress–dilatancy model for granular soil and soil-structure interface under monotonic and cyclic loads     

Sun  Yifei  Sumelka  Wojciech  Gao  Yufeng  Nimbalkar  Sanjay 《Acta Geotechnica》2021,16(10):3115-3132

The stress–dilatancy relation is of critical importance for constitutive modelling of geomaterial. A novel fractional-order stress–dilatancy equation had been developed for granular soil, where a nonlinear stress–dilatancy response was always predicted. However, it was experimentally observed that after a certain extent of shearing, an almost linear response between the stress ratio and the dilatancy ratio, rather than the nonlinear response, usually existed. To capture such stress–dilatancy behaviour, a new fractional stress–dilatancy model is developed in this study, where an apparent linear response of the stress–dilatancy behaviour of soil after sufficient shearing is obtained via analytical solution. As the fractional order varies, the derived stress–dilatancy curve and the associated phase transformation state stress ratio keep changing. But, unlike existing researches, no other specific parameters, except the parameter related to fractional order, concerning such shift are required. Then, the developed stress–dilatancy model is applied to constitutive modelling of granular soil and soil–structure interface, for further validation. A series of test results of different granular soils and soil–structure interfaces under different loading conditions are simulated and compared, where a good model performance is observed.

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