VIDEO AND PHOTOGRAPHIC SPECTROSCOPY OF 1998 AND 2001 LEONID PERSISTENT TRAINS FROM 300 TO 930 nm

Spectra of persistent meteor trains were observed at wavelength between 300 and 930 nm. Two obtained train spectra during the 1998 and 2001 Leonid meteor showers are reported here. During the 1998 Leonids, one train was detected by a photographic camera with a spectrograph covering 370–640 nm region. On the other hand, during the 2001 Leonids, video observations were carried out using image intensified cameras in ultraviolet (UV), visible and near infrared (near-IR) wavelengths. Temperatures in persistent trains have been measured by atmospheric O₂ A(0,1) band at the wavelength near 864.5 nm. From a video spectrum obtained just 7 s after parent fireball’s flare, a rotational temperature of 250 K at altitude of 88.0±0.5 km was estimated. We can say that the cooling time scale of train strongly depends on the initial mass of its fireball at least for Leonids. Based on cooling constant calculated from our results, we estimated a temperature of ∼ ∼130 K as a final exothermic temperature at early stage of persistent trains.     

Images of post-flare coronal structures in X-rays

This is an extended abstract of several papers mentioned in the references describing extensive coronal structures related to radio continua and imaged in > 3.5 keV X-rays.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985.     

Some Aspects of Meteoric Head Echo Velocity Determination

Velocity determination of 131 head echoes recorded during Perseid meteor shower observations by the Canadian 2 MW radar, has been performed under the assumption of either their constant velocity or of its linear change with time. Even though the constant velocities concentrated at 60 km s-1 generally accepted for the Perseids, a substantial number of echoes had velocities either lower than 60 km s-1 or greater than this value. The inclusion of variable velocity into considerations led to surprising result that a great portion of the head echoes accelerated (3 possibly decelerating echoes in comparison with 33 accelerating cases on the level of relative standard deviations of output parameters not exceeding 10%). It seems that the allocation of the ionization responsible for the head echo is not entirely identical with the instantaneous meteoroid position. As a consequence, the velocity derived from the measured head echo coordinates can differ from the velocity of parent body. We are not able to explain this finding at present. This revised version was published online in July 2006 with corrections to the Cover Date.     

Anomalous induction across Europe

Summary Using real induction vector data, collected at 958 European observation sites, together with our data from the Bohemian Massif and the West Carpathians, we have generated a contour map of the transfer function TF1 (corresponding to transfer function A in Wiese's relation). Only the zero contour is retained and shown on the map. It clearly marks the main anomalous induction zones, related to internal structural inhomogeneities, across Europe.     

Longitudinal distribution of PCA sources on the sun

For 181 PCA's recorded during the years 1956–1969 the association with flares is studied. Both the number of events which cannot be associated with any flare on the visible hemisphere, as well as the longitude distribution of identified proton flares, lead to the conclusion that 25–30% of PCA's are caused by flares behind the western solar limb. PCA's of this kind are mostly small. During the investigated years no PCA > 13 dB and possibly no PCA > 8.5 dB were caused by flares behind the limb, while hardly 60% of PCA's < l dB had their origin on the visible hemisphere. While the sources of GLE's and of PCA's in general, are centered around 50°W which corresponds to the average curvature of the magnetic field lines in interplanetary space, the strongest PCA's (> 8.5 dB) show an anomalous longitude distribution centered around ∼ 20°W. It is suggested that this anomaly may be a consequence of the fact that in strong PCA events the kinetic energy density of protons below 100 MeV becomes comparable to the magnetic energy density in space, thus leading to a ‘straightening’ of the magnetic field lines.     

Aufgaben der Felsmechanik bei neuzeitlichen Tunnelrekonstruktionen

Zusammenfassung Aufgaben der Felsmechanik bei neuzeitlichen Tunnelrekonstruktionen. Für die neuzeitliche Tunnelbauweise müssen neue Erkundungsmethoden mit erweitertem Umfang felsmechanischer Prüfungen angewandt werden. Diese Forderung soll ebenso bei Rekonstruktionen erfüllt werden. Außer den mechanischen Eigenschaften werden auch die innere Spannung im Felsmassiv und in der Ausmauerung, die Mächtigkeit der gelockerten Zone sowie die Injektions- und Verankerungsmöglichkeit bestimmt.

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Summary The Function of Rock Mechanics in Modern Tunnelling. For modern methods of tunnel driving it is necessary to apply new procedures of geological investigations including large-scale rock mechanics tests. This view holds equally for reconstruction projects. In addition to the mechanical properties of the rock masses it is necessary to determine the intrinsic stresses in the rock and in the tunnel lining, the thickness of the inelastic (relaxed) zone around the tunnel, as well as the possibility of grouting and anchoring.

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Résumé Application de la mécanique des roches aux méthodes modernes de construction et de reconstruction des tunnels. Dans la technique moderne des tunnels il est nécessaire d'appliquer de nouvelles méthodes de reconnaissance comportant davantage d'essais de mécanique des roches. La même exigence est valable pour la reconstruction des tunnels. Outre les propriétés mécaniques du massif rocheux, on déterminera aussi les contraintes dans le rocher et dans le revêtement, l'épaisseur de la zone décomprimée et même les possibilités d'injection et de boulonnage.

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Vortrag, gehalten beim XIX. Geomechanik-Kolloquium in Salzburg am 17. Oktober 1969.

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