The article presents the ways of defining and understanding hope in Polish, English and American literature. The basic theses are: 1) hope is an ambivalent phenomenon, 2) hope is connected with the work of consciousness and imagination, 3) hope conjures up visions of the alternative existential and social solutions, 4) hope is a passion and a way of knowing, 5) hope constitutes the keystone of artistic and academic activity.
The International Congress on Ultrasonics'2011 held in Gda?sk, Poland was the third one (after Viena'2007, Austria and Santiago'2009, Chile) over the world meeting of the ultrasonics community, continuing a long tradition of Ultrasonics International Conferences (organized every second year since 1963 to 2005), as well as World Congresses on Ultrasonics (organized every second year since 1995 to 2005). Last 6 years experience of foundation of ICU congresses have shown a real progress in global integration process of the ultrasonics community and provided an excellent platform for the professional knowledge, exchange among scientists and engineers from academic and industrial centers as well as from other institutions and places of ultrasonics studies and applications.
Ultrasonics as multi-disciplinary field covers a great number of topics from fundamental physical aspects through chemical, biological, medical, material inspections and others branches to many applications. All contributions of topics of the field of ultrasonics were presented during the ICU'2011 in Gdańsk, and the meeting provided a valuable and unique opportunity for participants to exchange their achievements and experience as well as to enlarge their international contacts on the field.
The Committee on Acoustics of the Polish Academy of Sciences was founded in 1964 by the reso lution of the General Assembly of the Polish Academy of Sciences, within its Division of Engineering Sci ences (Division 4). The idea of creating the Committee was brought up by Professor Ignacy Malecki, a distinguished scientist, an academic teacher, and an internationally acclaimed authority on acoustics.
The 11th School on Acousto-optics and its Appli-cations was held during the ICU'2011 - International Congress on Ultrasonics'2011, Gdansk, Poland, 5-8 September 2011, incorporated within the Congress as one of the six structured sessions named as Acousto-optics in the first and the second days being one of the four parallel sessions of other ultrasonic topics of the Congress.
About 60-80 people attended the acousto-optics sessions where 16 papers were presented by participants from Algeria, Belgium, Brasile, France, Japan, Lithuania, Poland, Russia.
The paper deals with the properties and microstructure of Reactive Powder Concrete (RPC), which was developed at Cracow University of Technology. The influence of three different curing conditions: water (W), steam (S) and autoclave (A) and also steel fibres content on selected properties of RPC was analyzed. The composite characterized by w/s ratio equal to 0.20 and silica fume to cement ratio 20%, depending on curing conditions and fibres content, obtained compressive strength was in the range from 200 to 315 MPa, while modulus of elasticity determined during compression was about 50 GPa. During three-point bending test load-deflection curves were registered. Base on aforementioned measurements following parameters were calculated: flexural strength, stress at limit of proportionality (LOP), stress at modulus of rapture (MOR), work of fracture (WF), and toughness indices I₅, I₁₀ and I₂₀. Both amount of steel fibres and curing conditions influence the deflection of RPC during bending.
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