Variable stars in the globular cluster NGC 6362     

Beata Mazur  Janusz Kaluzny  Wojciech Krzemi&#;ski 《Monthly notices of the Royal Astronomical Society》1999,306(3):727-735

We report the results of a CCD search for short-period variables in the field of a southern globular cluster NGC 6362. We identified 19 new candidate variables, five of which are cluster RR Lyraes, four are probable SX Phe-type stars and eight are eclipsing binaries. Of the discovered binaries, three are EA-type systems, two of which are located on the cluster CMD in the turn-off region and the third 1 mag above the turn-off point, in the yellow straggler region. Five other systems are of W UMa type, three of which are foreground objects and two are likely cluster members. The remaining two candidates exhibit a modulation of the brightness level with an amplitude of 0.1–0.2 mag; further observations are needed to reveal the nature of their variability. Phased VI light curves for 20 variables (18 RR Lyrae stars and two blue stragglers) located in the central region of the cluster are presented.  相似文献   

Reliability with respect to settlement limit-states of shallow foundations on linearly-deformable subsoil   总被引：1，自引：0，他引：1  

Jerzy Bauer  Wojciech Pu a 《Computers and Geotechnics》2000,26(3-4):281-308

A step by step procedure for applying the response surface and SORM methods in estimating the reliability index associated with exceeding a certain allowable settlement level by a shallow foundation is presented in this paper. Two random variables, the Young modulus and Poisson's ratio, of lognormal and beta distribution respectively, in a single soil layer are taken into account. A linearly-deformable model of soil is assumed which is most frequently used in engineering practice when the serviceability limit state is considered. The main problem encountered in using the response surface methodology was the existence of false design points that prevented coordinate calculations of the real ones. Two procedures were employed. The first one consisted of widening the area covered by the response surface (polynomial of the second degree) with an additional “oedometric” term. Inserting the oedometric term improves the quality of the fitting and enables one to extend the range of approximation. The latter added a barrier to prevent the procedure from moving into the false design point region. Moreover, the paper presents the effect of random variation of the Young modulus E and Poisson's ratio ν as well as their mutual correlation, on the reliability index associated with exceeding the assumed level of a shallow foundation settlement.  相似文献   

Non-integrability of the dumbbell and point mass problem     

Andrzej J. Maciejewski  Maria Przybylska  Leon Simpson  Wojciech Szumiński 《Celestial Mechanics and Dynamical Astronomy》2013,117(3):315-330

This paper discusses a constrained gravitational three-body problem with two of the point masses separated by a massless inflexible rod to form a dumbbell. This problem is a simplification of a problem of a symmetric rigid body and a point mass, and has numerous applications in Celestial Mechanics and Astrodynamics. The non-integrability of this system is proven. This was achieved thanks to an analysis of variational equations along a certain particular solution and an investigation of their differential Galois group. Nowadays this approach is the most effective tool for study integrability of Hamiltonian and non-Hamiltonian systems.  相似文献   

Bayesian approach to tomographic imaging of rock-mass velocity heterogeneities     

Wojciech Dębski 《Acta Geophysica》2013,61(6):1395-1436

  相似文献   

Numerical simulation of catastrophic flood: the case study of hypothetical failure of the Bielkowo hydro-power plant reservoir     

Michał Szydłowski  Wojciech Szpakowski  Piotr Zima 《Acta Geophysica》2013,61(5):1229-1245

The numerical modeling of flood wave propagation following the hypothetical breaks of the embankments of the Bielkowo hydro-power plant storage reservoir (Kolbudy II Reservoir) on the Radunia River in Poland has been presented. The results of computations were used to estimate the parameters of the flood waves, which are indispensable for the flood zone determination and mapping and then for the flood risk analysis. When estimating the reach and area of the inundation, related to the embankments failures, digital terrain model, and mathematical model of flood wave propagation are necessary. For the numerical simulations of flood, the mathematical model of free surface, two-dimensional unsteady water flow was applied. Four locations of potential breaks of the reservoir embankments were considered. The computed flood zones were presented on the flood hazard maps. The maps have been used by the local authorities and the dam owner to manage the flood risk related to hydro-power plants operations on the Radunia River. This type of research has been done for the first time for the water plant managed by the ENERGA Elektrownie Straszyn.  相似文献   

Geochemical and statistical approach to evaluate background concentrations of Cd,Cu, Pb and Zn (case study: Eastern Poland)   总被引：2，自引：2，他引：0  

Wojciech Zgłobicki  Lesia Lata  Andrzej Plak  Marek Reszka 《Environmental Earth Sciences》2011,62(2):347-355

An attempt was made to evaluate background concentrations of Cd, Cu, Pb and Zn by means of geochemical and statistical approach. As many as 753 samples taken from 51 profiles located in Eastern Poland were analysed. For the estimation of geochemical background values, direct geochemical methods and a statistical analysis for the whole population of samples were applied. Average values of heavy metal concentration in loess sediments (bedrock) as well as in profiles not affected by human activity were measured. The iterative 2σ technique and calculated distribution function were chosen as statistical methods. The resulting values (background concentrations range) were as follows: Cd 0.5–0.9 mg kg⁻¹, Cu 5–16 mg kg⁻¹, Pb 12–26 mg kg⁻¹ and Zn 31–47 mg kg⁻¹. All the methods applied gave similar results. The highest deviation of the background was noted for Cu and the lowest for Zn. The lowest values of background were obtained for loess sediments and the highest in the case of the multiple 2σ method.  相似文献   

The influence of track configuration and multibeam echosounder parameters on the accuracy of seabed DTMs obtained in shallow water     

Wojciech Maleika 《Earth Science Informatics》2013,6(2):47-69

This article presents research that aims to assess the accuracy of seabed bathymetry models on the basis of measurements carried out using a multibeam echosounder. It discusses the problem of accuracy assessment which occurs at particular stages of the creation of digital terrain models (DTMs), and analyzes the influence of both the individual multibeam echosounder parameters and the procedures adopted during the survey on the modeling process’s accuracy. Factors that may affect accuracy include the device’s measurement accuracy, the boat speed, the track configuration, the beam width and the selected interpolation method. The article does not deal with errors due to navigation and vessel motion, these being taken to be of the highest possible accuracy. For the research we developed a virtual survey simulator. Recommendations for how to optimize the measurement process while ensuring the created models are of a high quality are presented later in the paper.  相似文献   

Atlases of geothermal waters and energy resources in Poland     

Wojciech Górecki  Anna Sowiżdżał  Marek Hajto  Anna Wachowicz-Pyzik 《Environmental Earth Sciences》2015,74(12):7487-7495

  相似文献   

Explicit stress integration with error control for the Barcelona Basic Model.: Part II: Algorithms efficiency and accuracy     

Wojciech T. Sołowski  Domenico Gallipoli 《Computers and Geotechnics》2010,37(1-2):68-81

The paper compares the accuracy and efficiency of explicit stress integration schemes for elasto-plastic unsaturated soil models with automatic error control. Numerical tests are performed with reference to the Barcelona Basic Model (BBM), one of the most popular elasto-plastic models for unsaturated soils, by using eight explicit Runge–Kutta algorithms of various order as well as a novel application of the extrapolation method described in the companion paper. Initially, the results obtained from the lowest order Runge–Kutta scheme (i.e. Modified Euler) as well as the extrapolation method are checked against accurate solutions of a number of BBM paths involving changes of strains and suction. Subsequently, the efficiency and accuracy of all algorithms are assessed for generic increments of strains and suction, while the difference between two alternative error control methods is also analysed. The results presented, although strictly valid for the Barcelona Basic Model, are expected to be general and relevant to other similar unsaturated elasto-plastic models formulated in terms of two independent stress variables such as net stress and suction.  相似文献   

Generation and propagation of transient nonlinear waves in a wave flume     

Wojciech Sulisz  Maciej Paprota 《Coastal Engineering》2008

A semi-analytical nonlinear wavemaker model is derived to predict the generation and propagation of transient nonlinear waves in a wave flume. The solution is very efficient and is achieved by applying eigenfunction expansions and FFT. The model is applied to study the effect of the wavemaker and its motion on the generation and propagation of nonlinear waves. The results indicate that the linear wavemaker theory may be applied to predict only the generation of waves of low steepness for which the nonlinear terms in the kinematic wavemaker boundary condition and free-surface boundary conditions are of secondary importance. For waves of moderate steepness and steep waves these nonlinear terms have substantial effects on wave profile and wave spectrum just after the wavemaker. A wave spectrum corresponding to a sinusoidally moving wavemaker possesses a multi-peak form with substantial nonlinear components, which disturbs or may even exclude physical modeling in wave flumes. The analysis shows that the widely recognized weakly nonlinear wavemaker theory may only be applied to describe the generation and propagation of waves of low steepness. This is subject to further restrictions in shallow and deep waters because the kinematic wavemaker boundary condition as well as the nonlinear interaction of wave components and the evolution of wave energy spectrum is not properly described by weakly nonlinear wavemaker theory. Laboratory experiments were conducted in a wave flume to verify the nonlinear wavemaker model. The comparisons show a reasonable agreement between predicted and measured free-surface elevation and the corresponding amplitudes of Fourier series. A reasonable agreement between theoretical results and experimental data is observed even for fairly steep waves.  相似文献