Observations of Solar X-ray Spectra by the DIOGENESS and RESIK Spectrometers Onboard the <Emphasis Type="Italic">CORONAS-F</Emphasis> Satellite

The first scientific results of the analysis of the X-ray spectra of flares and active regions in the solar corona obtained by Polish-led spectrometers RESIK and DIOGENESS onboard the CORONAS-F satellite are presented. The instruments were designed and made in the Solar Physics Division of the Space Research Center of the Polish Academy of Sciences (SRC PAS, Wroclaw, Poland). The Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (IZMIRAN, Russia) and the Astronomical Institute of the Czech Academy of Sciences also participated in designing the DIOGENESS spectrometer, while IZMIRAN (Russia), Mullard Space Science Laboratory (MSSL, Great Britain), Rutherford Appleton Laboratory (RAL, Great Britain), and Naval Research Laboratory (NRL, United States) contributed to the development of the RESIK spectrometer. In the paper, we give spectra obtained in a number of previously unstudied spectral ranges and a preliminary identification of new spectral lines. The results for the shifts of the X-ray spectral lines observed with the use of a so-called dopplerometer configuration are also presented. Methods for determining the abundances of the rare elements in the solar corona, including chlorine, potassium, and argon, are described.     

Radioisotopic evidence of perturbations of recent sedimentary record in lakes: a word of caution for climate studies

The rate of climatic change estimated from the gradient of signals recorded in lake sediments may be erroneous if post-depositional perturbations are overlooked. A smear out of a pulse signal, over a variable thickness of core section, due to physical or biological mixing, is a well known phenomena. Much less attention is paid to a possible overestimation of the rate of change when a part of record is missing due to an erosion event. In this paper we show a few examples of recent lake sediment perturbations and the resulting distortions in the time scale, as documented by short-lived radionuclides.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program     

РЕЗУЛЬТАТЫ АНАЛИЗА МЕТОДАМИ ХОЙНИЦКОГО И ВЕНЕДИКОВА ДОЛГОВРЕМЕННЫХ НАБЛЮДЕНИЙ НА ЧЕЩСКНХ ПРИЛИВНЫХ СТАНЦИЯХ

Zusammenfassung Mit Benutzung der langfristigen Gezeitenbeobachtungsreihen mit Hilfe der Klinometer und des Gravimeters auf den tschechoslowakischen Gezeitenstationen werden die Methoden der Analyse von Chojnicki und Venedikov verglichen. Die in Tab. 1–5 zusammengefassten Ergebnisse zeigen beide benutzten Methoden als gleichwertig. Zum Hauptvorteil der Methode von Chojnicki gehört die Möglichkeit der Berechnung von Gezeitenparametern auch für langperiodische Wellen (Tab. 2, 4 und 5).

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Flotation of synthetic zinc carbonate using potassium ethylxanthate

An attempt at flotation of fine grains of zinc carbonate using potassium ethylxanthate as the collector and sulphydryl and copper ions as the activators has been undertaken. Results of the flotation tests have been interpreted in terms of the adsorption of activating agents as well as the grain size effect.     

Recognition of the zones of seismic hazard in Polish Coal mines by using a seismic method

In the Upper Silesian Coal Field the seismic hazard induced by mining operations in collieries is closely related to the rockburst hazard. A seismic method is used for premonitory recognition of the zones of seismic hazard. It takes advantage of the relationship between the velocity of propagation of seismic waves and the state of stress existing in the rock. It consists of the determination of the velocity field of artificially induced seismic waves in a studied fragment of the rock, and of locating the velocity anomaly. The position of the velocity anomaly zones and their intensity are the basis for estimating the seismic hazard in advance of mining works.     

Comparison of three methods used for calculation of the differential emission measure

A comparison of three methods used for multi-temperature analysis of solar X-ray spectra is presented. The modified method of conjugate gradients appears to be very efficient for minimizing ² subject to regularizing (smoothing) constraints. The Withbroe-Sylwester method also ensures good fits, particularly when computations are carried out in wide temperature intervals. Both methods are much faster than the Maximum Entropy method and yield models with an entropy close to that of the Maximum Entropy models. The reliability of revealing the shape of the differential emission measure is discussed. It is shown that the total emission measure and the plasma thermal energy content can be calculated to within a few percent.     

Noise-Dependent Adaption of the Wiener Filter for the GPS Position Time Series

Various methods have been used to model the time-varying curves within the global positioning system (GPS) position time series. However, very few consider the level of noise a priori before the seasonal curves are estimated. This study is the first to consider the Wiener filter (WF), already used in geodesy to denoise gravity records, to model the seasonal signals in the GPS position time series. To model the time-varying part of the signal, a first-order autoregressive process is employed. The WF is then adapted to the noise level of the data to model only those time variabilities which are significant. Synthetic and real GPS data is used to demonstrate that this variation of the WF leaves the underlying noise properties intact and provides optimal modeling of seasonal signals. This methodology is referred to as the adaptive WF (AWF) and is both easy to implement and fast, due to the use of the fast Fourier transform method.

     

Influence of a method of evaluation of the curvature of flexible vegetation elements on vertical distributions of flow velocities

Methods of computing the deflections of flexible vegetation elements under the dynamic pressure of water were presented in the paper. Two methods, based on Euler-Bernoulli beam theory, were discussed, one designed for small deflections and the other, generalized one, also for larger deflections. The choice of the method for computations of deflections was discussed from the perspective of the computation of flow velocities above flexible vegetation. Computational results were compared with laboratory experiments and it was found that the simplified, computationally less expensive method may be used in many practical situations without deterioration of the results.