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On the Probability Distribution of Earth Orientation Parameters Data
T. Niedzielski, , A. K. Sen, W. Kosek
Artificial Satellites , 2009, DOI: 10.2478/v10018-009-0017-4
Abstract: Earth Orientation Parameters (EOPs), i.e. pole coordinates (xp, yp), Universal Time (UT1-UTC), and celestial pole offsets (dX, dY), are the transformation parameters between the International Terrestrial Reference Frame (ITRF) and the International Celestial Reference Frame (ICRF). It is customarily assumed that each of the EOP time series follows the normal distribution. The normality assumption has been used specifically in EOP prediction studies. The objective of this paper is to investigate the normality hypothesis in detail. We analysed the daily time series of xp, yp, UT1-UTC, length-of-day (Δ), dX, and dY in the time interval from 01.01.1962 to 31.12.2008. The UT1-UTC data were transformed to UT1R-TAI by removing leap seconds and the tidal signal using the IERS model. The tidal effects δΔ were also removed from the Δ time series and Δ - δΔ data were obtained. Furthermore, we constructed the residuals of these time series using least-squares fit. We evaluated the skewness and kurtosis and tested their statistical significance by the D'Agostino and the Anscombe-Glynn tests, respectively. In addition, the Anderson-Darling test for the normal distribution was applied. It was found that the xp, yp time series and their residuals slightly depart from the normal distribution, but this departure is rather due to marginal flattening/narrowing of the probability density function than due to extreme values. The UT1R-TAI time series and its residuals were also classified as non-Gaussian, however, the deviations from the normal distribution are again slight. The similar results hold for the Δ - δΔ data, but some of its residuals were found to be Gaussian. We noticed that the celestial pole offsets, dX and dY, tend to deviate from the Gaussian distribution. In addition, we examined the determination errors of EOP data and found them to depart significantly from the normal distribution.
Empirical Hydrologic Predictions for Southwestern Poland and Their Relation to Enso Teleconnections
Tomasz Niedzielski
Artificial Satellites , 2010, DOI: 10.2478/v10018-010-0002-y
Abstract: Recent investigations confirm meaningful but weak teleconnections between the El Ni o/Southern Oscillation (ENSO) and hydrology in some European regions. In particular, this finding holds for Polish riverflows in winter and early spring as inferred from integrating numerous geodetic, geophysical and hydrologic time series. The purpose of this study is to examine whether such remote teleconnections may have an influence on hydrologic forecasting. The daily discharge time series from southwestern (SW) Poland spanning the time interval from 1971 to 2006 are examined. A few winter and spring peak flows are considered and the issue of their predictability using empirical forecasting is addressed. Following satisfactory prediction performance reported elsewhere, the multivariate autoregressive method is used and its modification based on the finite impulse response filtering is proposed. The initial phases of peak flows are rather acceptably forecasted but the accuracy of predictions in the vicinity of local maxima of the hydrographs is poorer. It has been hypothesized that ENSO signal slightly influences the predictability of winter and early spring floods in SW Poland. The predictions of flood wave maxima are the most accurate for floods preceded by normal states, less accurate for peak flows after La Ni o episodes and highly inaccurate for peak flows preceded by El Ni o events. Such a finding can be interpreted in terms of intermittency. Before peak flows preceded by El Ni o there are temporarily persistent low flows followed by a consecutive melting leading to a considerable intermittency and hence to difficulties in forecasting. Before peak flows preceded by La Ni o episodes there exist ENSO-related positive temperature and precipitation anomalies in SW Poland causing lower, but still considerable, intermittency and thus better, but not entirely correct, predictability of hydrologic time series.
Non-Linear Sea Level Variations in the Eastern Tropical Pacific
Tomasz Niedzielski
Artificial Satellites , 2010, DOI: 10.2478/v10018-010-0001-z
Abstract: The objective of this paper is to provide an insightful interpretation for the non-linearity of the inter-annual signal in sea level change in the eastern tropical Pacific. Such a non-linearity has been already discussed elsewhere for global ocean. Herein, the residual sea level anomaly time series from TOPEX/Poseidon and Jason-1 altimetry is obtained by removing the significant deterministic signals from the original sea level anomaly data. Since the eastern tropical Pacific is a profound region where many processes responsible for driving the El Ni o/Southern Oscillation (ENSO) act, it is possible to link a few of them with the non-linearity of sea level change. In particular, not only local, usually weak, oceanatmosphere interactions exist in the eastern equatorial Pacific but this region is also remotely impacted by climatic processes acting in the western equatorial Pacific where the oceanatmosphere coupling is the strongest. The detected non-linearity of sea level change is due to the asymmetry between warm and cold ENSO episodes. Such an asymmetry can be driven by the non-linear dynamical heating associated with strong ENSO events.
Socijalna nauka Crkve
Niedzielski, Felix
- , 1940,
Abstract: Hr？ak ID: 5993
The 1999 outburst of the eclipsing and recurrent nova U Scorpii
U. Munari,T. Tomov,L. Tomasella,T. Zwitter,P. Bonifacio,P. Molaro,P. Selvelli,A. Niedzielski,A. Pearce
Physics , 1999,
Abstract: The spectroscopic and photometric evolution of the 1999 outburst of the eclipsing and recurrent nova U Sco is presented. The photometric evolution closely matches that of the previous events. The FWZI=10,000 km/sec for emission lines at maximum has decreased to 4000 km/sec by day +23, with continuous and dramatic changes in the line profiles. No nebular line has become visible and the ionization degree has increased during the brightness decline. A not previously reported and quite puzzling splitting of the emission lines into three components after the first two weeks is outstanding in our spectra. The radiated luminosity is found to be a tiny fraction of that of classical novae for any reasonable distance to U Sco.
An Application of Low-Order Arma and Garch Models for Sea Level Fluctuations
Tomasz Niedzielski, , Wieslaw Kosek
Artificial Satellites , 2010, DOI: 10.2478/v10018-010-0003-x
Abstract: The paper presents the analysis of geographically-dependent irregular sea level fluctuations, often referred to as residual terms around deterministic signals, carried out by means of stochastic low-order autoregressive moving average (ARMA) and generalised autoregressive conditional heteroscedastic (GARCH) models. The gridded sea level anomaly (SLA) time series from TOPEX/Poseidon (T/P) and Jason-1 (J-1) satellite altimetry, commencing on 10th January 1993 and finishing on 14th July 2003, has been examined. The aforementioned models, limited to low-orders being combinations of 0,1 and 2, have been fitted to the SLA data. The root mean square and the Shapiro-Wilk test for the normal distribution have been used to calculate statistics of the residuals from these models. It has been found that autoregressive (AR) models as well as ARMA ones serve well the purpose of adequate modelling irregular sea level fluctuations, with a successful fit in some patchy bits of the equatorial Pacific. In contrast, GARCH models have been shown to be rather inaccurate, specifically in the vicinity of the tropical Pacific, in the North Pacific and in the equatorial Indian Ocean. The pattern of the Tropical Instability Waves (TIWs) has been noticed in the statistics of AR and ARMA model residuals indicating that the dynamics of these waves cannot be captured by the aforementioned linear stochastic processes.
A Search for Planets with SALT
Monika Adamów,Andrzej Niedzielski
Physics , 2009, DOI: 10.1051/eas/1042006
Abstract: As the SALT High Resolution Spectrograph completion is nearing we plan to extend the Pennsylvania-Torun Planets Search (PTPS) with HET to the southern hemisphere. Due to overlap of the skies available for both HET and SALT in the declination range (+10, -10) deg some cooperation and immediate follow up is possible. Here we present, as an example, a $\sim$ 1000 star sample of evolved stars for the future SALT Planet Search.
Application of microwave/radio frequency and radio frequency/magnetron sputtering techniques in polyurethane surface modification
W. Kaczorowski,D. Batory,P. Niedzielski
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: The aim of the study is the analysis of the possibilities of application of MW/RF PACVD and RF PACVD/MS systems in polyurethane surface modification.Design/methodology/approach: As the substrates samples made out of the biocompatibile polyurethane were used. Modifications were performed in MW/RF PACVD and RF PACVD/MS reactors using different gases and process parameters. Topography, thickness and contact angle were measured using Atomic Force Microscopy, Profilometry and Contact Angle Measuring Instrument.Findings: Optimal plasma parameters ensuring deposition of carbon layers without surface degradation were worked out. Deposited layers were less than 500 nm thick and presented the wetting angle value more than 90o. During the examinations the influence of the gas atmosphere and process parameters used for the preliminary substrates modification were investigated. Obtained results prove the possibility of application of MW/RF PACVD and RF PACVD/MS techniques in deposition of carbon-based coatings on polyurethane substrates used for artificial heart chambers manufacturing.Research limitations/implications: Modification of polymer surface has to be conducted at low temperatures, up to 100oC. Unfortunately not all CVD and PVD methods used in this field guarantee the adequate adhesion of manufactured layers deposited in such low temperatures. So far the most promising results were obtained with use of PLD (pulsed laser deposition) techniques. However application of MW (microwave) low temperature plasma source and combination of magnetron sputtering technique with RF (radio frequency) plasma source seems to be equally interesting techniques.Originality/value: Optimization of carbon layers deposition techniques on polyurethane substrates can be helpful in improvement of modern artificial heart chambers construction. All investigation results obtained in his field attend to work out the new generation of cardiosurgical implants within the confines of multiyear Project Polish Artificial Hart”.
Bisector Measurements of HD 102272
Grzegorz Nowak,Andrzej Niedzielski,Aleksander Wolszczan
Physics , 2009,
Abstract: Searches for planets around massive stars are essential for developing general understanding of planet formation and evolution of the planetary systems. The main objective of the Pennsylvania - Torun Planet Search is detection of planets around G-K subgiants and giants through precision radial velocity (RV) measurements with iodine absorption cell using HET HRS spectrograph. However, the long period radial velocity variations of red giants may also have other than planetary nature (e.g. a non-radial pulsations or rotational modulation in presence of starspots). In this work we present bisector analysis of cross-correlation functions (CCF) constructed from the spectra used for radial velocity determination but cleaned from the iodine lines for the second red giant with planets from our survey HD 102272.
Transit timing variation and activity in the WASP-10 planetary system
G. Maciejewski,D. Dimitrov,R. Neuhaeuser,N. Tetzlaff,A. Niedzielski,St. Raetz,W. P. Chen,F. Walter,C. Marka,S. Baar,T. Krejcova,J. Budaj,V. Krushevska,K. Tachihara,H. Takahashi,M. Mugrauer
Physics , 2010, DOI: 10.1111/j.1365-2966.2010.17753.x
Abstract: Transit timing analysis may be an effective method of discovering additional bodies in extrasolar systems which harbour transiting exoplanets. The deviations from the Keplerian motion, caused by mutual gravitational interactions between planets, are expected to generate transit timing variations of transiting exoplanets. In 2009 we collected 9 light curves of 8 transits of the exoplanet WASP-10b. Combining these data with published ones, we found that transit timing cannot be explained by a constant period but by a periodic variation. Simplified three-body models which reproduce the observed variations of timing residuals were identified by numerical simulations. We found that the configuration with an additional planet of mass of $\sim$0.1 $M_{\rm{J}}$ and orbital period of $\sim$5.23 d, located close to the outer 5:3 mean motion resonance, is the most likely scenario. If the second planet is a transiter, the estimated flux drop will be $\sim$0.3 per cent and can be observable with a ground-based telescope. Moreover, we present evidence that the spots on the stellar surface and rotation of the star affect the radial velocity curve giving rise to spurious eccentricity of the orbit of the first planet. We argue that the orbit of WASP-10b is essentially circular. Using the gyrochronology method, the host star was found to be $270 \pm 80$ Myr old. This young age can explain the large radius reported for WASP-10b.
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