The effect of air humidity on oscillatory flow around the NACA 0012 airfoil was investigated experimentally at Mach number M=0.71 and airfoil angle of attack a=8.5''. The background tlow oscillations were produced by a rotating rectangular plate placed downstream of the airfoil. The generated oscillation frequencies were in the range from 0.5 up to 1.5 of the buffet frequency. The presented results shown that the normal aerodynamic force variations strongly depend on the excitation frequency and reach a maximum value at frequencies typical to the buffet. The increase of the air humidity leads to considerable diminishing of the aerodynamic force variation.

Subfossil trunks of oak (Quercus robur L. and Q. petraea Lieb.) are fundamental for construction of long dendrochronological standards for southern Poland. In the last three years over 400 new oak trunks from alluvial deposits from the basins of the rivers Vistula and Odra were analysed. Most trunks came from the last 2500 years and the produced local chronologies permitted for improvement of the standard chronology POLAND2, covering the period 474 BC-I 555 AD. Subfossil oak trunks from several sites in the river Vistula basin (Grabie, Wolica, Podolsze and others) and from alluvia of the river Odra in Wrocław enabled construction of a new long chronology C_3000E, spanning the years 1795- 612 BC. This chronology was absolutely dated through teleconnection with standards for southern Germany. A row of floating chronologies, dated with the radiocarbon method, was established for the older periods of Holocene. They cover the following intervals: ca. 670-400 BC, ca. 2200-1900 BC, ca. 3400-3100 BC, ca. 3800-3600 BC and ca. 6650-6150 BC. Subfossil oak chronologies constructed by the author, together with standards based on living trees, monuments of wooden architecture, and archaeological timbers from Wielkopolska (449- I 994 AD), Lower Silesia (780-1994 AD) and Małopolska (910-1997 AD) practically allow for absolute dating of oak timbers from the area of southern Poland coming from the last 4000 years.

The paper presents the conversion dynamics of basic nitrogen and phosphorus forms as main factors initiating eutrophication process in Naklo-Chechlo reservoir. Limnological investigations of recreation reservoir were carried out in the period from January to December 1996. The results of chemical analyses of water samples taken in two collecting points of the reservoir and a composition of surface run-off from the basin area, have been presented.

The question of the state affiliation of Upper Silesia which arose after WWI has been treated and perceived by today’s historians, if at all, as a typical German-Polish border conflict. Really however, it was both a European and an international problem of utmost significance. In it, French hegemonic and safety efforts, accumulated in and collided with Britain‘s classic policy of continental equilibrium. Both, Poland with its territorial claim on Upper Silesia and Germany in its struggle to preserve its territorial integrity, thus were not only players of political, diplomatic and military struggles for the second most important European industrial region, but rather objects of the interests of European great powers. This applied even more to the population which was actually to vote in the referendum on Upper Silesia affiliation. However, in its effort to weaken Germany and simultaneously gain control over the Ruhr, France favoured its ally Poland, to a much greater extent than Britain could in respect of Germany.

The paper presents application of guidance system for small, smart mortar missile. The presented control system is simple and inexpensive. It is based on a set of one time used impulse control engines and linear coordinator rotating with controlled object. Engines are mounted around the missile. There are no movable devices on the projectile board. The correcting impulses from rocket engines are perpendicular to main symmetry axis of the flying object and influence directly the centre of gravity of the guided missile. In the paper, authors describe the whole control system of the missile. Particular attention is focused on seeker and control devices. Numerical analysis presents some cases of the missile controlled flights.

The article examines the trends in social communication in Poland in 1980–1981. Having analyzed multiple sources and research studies, the author comes to the conclusion that in this watershed period in Polish postwar history was characterized not only by stricter control of the official information channels but also a grassroot pushback manifested in the rise of uncensored bulletins, leaflets and propaganda posters.