Dynamics Seminar

This Seminar was founded in 1962 and began its activity in October 1962, dealing mainly with methods of measurement in continuous media mechanics. Towards the end of the nineteen sixties more and more attention was being paid to the dynamics of processes beginning with empirical research first into dynamics and then into materials and construction fatigue.

It was then that the present name of the seminar was finally adopted. From the very beginning the Seminar was run by Dr Wacław Kasprzak.

In its first years the Seminar was chiefly concerned with methods and techniques of measurement used in applied mechanics and mechanical constructions. Scientific teams taking part in the seminar’s work carried out thorough research for industry checking the strain of prototype constructions. It was expected that on the basis of the performed measurements permission could be granted for the construction to be brought into industrial use and it would be possible to assess the possibilities of reducing its weight.

The latter expectations concerned mainly the so-called Lenta program that is the construction of pontoon bridges. The objective of that research was to reduce the weight of each pontoon by 30% in relation to the prototype under investigation. This research was conducted by: Wiesław Ćmikiewicz, Leszek Gołaski, Wacław Kasprzak, Tomasz Kobielak, Bertold Łysik, Stanisław Piesiak, professor Marek Zakrzewski, (The Institute Director and caring patron of the seminar).

As a result of the tests carried out the experimenters developed new methods for determining internal forces and stress distribution in mechanical constructions. Complete algorithmic foundations of the developed methods (practical methods reverse to applied strain analysis) were presented in the following works:

• L. Gołaski, W. Kasprzak, B. Lysik Stress Tests of Steel Constructions and Elements of Opencast Machines Dolnośląskie Biuro Projektów Górniczych [Lower Silesian Mining Project Agency] Problem Bulletins 46 Wrocław, 1968

• R. Kapała, W. Kasprzak, B. Lysik: Designing of Strain Measurements and Processing of their Results. Review of Publications, Series: Measurement Wroclaw University of Technology Institute of Materials Science Bulletin 2, 1968

• W. Kasprzak Theoretical Foundations for Methods of Measurement of Deformations and Derivative Values". Scientific Bulletins of Wroclaw University of Technology, Mechanics 21, 1967.

At the same time stress tests for policrystal structures were carried out. They were performed by: Wiesław Jarguliński, Wacław Kasprzak, Stefan Pilcer, Andrzej Pszonka, Mieczysław Wojtas, Jerzy Ziaja and Marek Zakrzewski. Research within the scope of stress measurements using roentgenographic methods (it should be noted here a special measuring roentgen apparatus was built for that purpose as early as in 1962) was summed up in the following works.

• W. Kasprzak, A. Pszonka, J Ziaja Assessment of the Deformation Degree in Separate Cristalites of Regular System by Means of X-Rays", Scientific Research of the Institute of Materials Science and Technical Mechanics, Wroclaw University of Technology, Studies and Materials No. 3, 1971.

• W. Kasprzak, St. Pilcer, M. Wojtas Theoretical and Practical Principles of the Stress Determination inside a Single-Grain of Policrystal". Bul. De L’Ac. Pol. Des Sci. Ser. Sci. Techn. 1974 vol. 22 nr 1.

Works on research into policrystal structures were presented in:

• W. Kasprzak Determination of Constants of Elasticity of Policrystals on the Basis ofElasticity Constants of Monocrystals*" Metallurgy Archives 1967, Vol. 12, Bulletin 2

At the turn of the 1960-ies researches were begun on automatic processing of tensometric measurements results. First works in that field were carried out by E. Macha and J. Halawa and they used analogue systems for that purpose. Then researchers’ attention concentrated on computer methods of constructing mathematical models on the basis of identification theory and dimensional analysis. Investigations were funded by Maria Sklodowska-Curie Fund (NSF), the American side being represented by professors Vadim Komkow and Eduard Haug.

At the same time a technical system was built which ensured full computerization of research in the Dynamics Laboratory. The first such setup was developed by using of mc Odra 1325 with SMA system (1973) together with complete software upgraded till the year 1983. The setup was described in a paper Computer System SMA-Odra 1325 in the Research Laboratory Wroclaw University of Technology, 1984 published by the University Information Library.

Operating system for this setup was worked out by Andrzej Stanisz. The study presenting it was edited by W. Kasprzak and prepared by: B. Lysik, K. Baranowski, E. Macha, J. Różewicz, A. Bergier, J. Dzikiewicz, A. Kośliński, Sch. Rej, M. Szata, I. Jakubowska, M. Kulisiewicz, St. Piesiak. In 1988 on the basis of the experience gained from the SMA-Odra System, a new one (CAMAC-SM-4) was developed. Its characteristics were presented in the paper “Computer Systems in Research and Industrial Laboratories CAMAC-SM-4 and CAMACMERA 60, Wroclaw University of Tchnology 1988 also edited by W. Kasprzak and co-authorship of: I. Jakubowska, A. Kośliński, J. Kozicki, W. Myszka, St. Piesiak, E. Rafajłowicz, W. Saladra, W Stanisz, i M. Szata.

Research on algorithmic procedures was conducted in a big team till the end of the 1980-ties. Apart from the authors listed above the team also included the authors of a textbook Computer System of Experiment Control edited by W. Myszka, published by WNT [Scientific and Technical Publishing House], Warsaw 1991. These were: A. Bartkowiak, B. Kasprzak, W. Kasprzak, M. Popkiewicz, E. Rafajłowicz, A. Sielicki, M. Szata, J. Zaleski, J. Zarzycki, R. Zmyślony, St. Zontek. Algorithms not included in the above publications were worked out by: R. Galar, M. Bazewicz, J. Halawa, K. Pelc, G. Ziętek, and also W. Mejbaum and S. Lebiediewa who worked on measurement information bank.

Research on automatic measurement processing were begun with development of an analogue system for determination of the state of stress (E. Macha 1970) and ended with a program library and automatic system CAMAC-SM-4 in 1991.

In 1967 researches were begun on identification of models of dynamic mechanical systems. They coincided with supplying the Dynamics Laboratory with Prodera system for modal analysis of dynamic systems; it was a gift from Inland Navigation Union, with which the laboratory collaborated (in the already mentioned Lenta program).

At first the research was conducted by Bronisław Okołów, W. Kasprzak, B. Lysik and K. Pelc. Soon several other researchers joined the team: Antoni Kośliński, Karol Baranowski, Tomasz Kobielak, Roman Galar, Maciej Kulisiewicz, Stanisław Piesiak, Teodor Torosiewicz and Mieczysław Szata.

That team conducted research for the Navigation Union, Jelcz Automobile Factory and Poltegor. The concepts of mathematical models identification of the system vibration was prepared on the base on work and power analysis by professor Adam Rybarski and professor Andrzej Krzywicki, who in the 1970-ies and in the beginning of the 1980-ies co-presided the seminar’s activities and put forward many interesting ideas to its members. Their expertise in differential equations was often helpful in solving several important problems. At that very time professor Czesław Ryll-Nardzewski conducted semestral lecture on the foundations of mathematics to the seminar members.

Research for motor industry crowned with an extensive monograph by T. Kobielak entitled Correlative characteristics of uneven road surfaces in Poland. The author of this monograph was greatly indebted to professor Stanisław Trybuła who was responsible for an adequate method of data filtering.

Seminarians also developed a special laboratory for Automobile Factory in Jelcz where vehicles prototypes were to have been tested. Researches into methods of identification of dynamic systems started by M. Kulisiewicz, St. Piesiak, and M. Szata have been conducted up till now. The research team is now headed by professor Maciej Kulisiewicz, apart from the above-mentioned Mirosław Bocian and Mariusz Wajda took and are still taking part in the team’s work. In the beginning investigations into this area concentrated on developing identification algorithms using models of nonlinear restitutive elements (e.g. of Duffig type) and afterwards the team shifted their attention to identification of vibration damping and energy diffusion in materials loaded with high-frequency dynamic excitations. New original scientific investigative methods were developed. They were based on the idea of both energy and power balance equations for discrete systems: linear and nonlinear as well as for degenerate systems, where internal forces are modeled with complex reologic relationships.

This group of works also embraces interesting results attained by Radosław Iwankiewicz (at present Hamburg University professor).

Apart from publications in scientific journals recently developed methods were presented in monographs and textbooks:

• M. Kulisiewicz, St. Piesiak Identification of Dynamic Properties of Mechanical Constructions, Wroclaw University of Technology, 1975.

• M. Kulisiewicz *Construction of Identification Methods for Selected Nonlinear Structures of Dynamic Models of Mechanical Systems, *Institute of Materials Science and Applied Mechanics, Wroclaw University of Technology, 1985 No 44, Monographs No 6.

• M. Kulisiewicz Modeling and Identification of Nonlinear Mechanical Systems under Dynamic Complex Loads, Wroclaw University of Technology Publishing House 2005.St.

• St. Piesiak Identification of Mechanical Systems in the Field of Nonlinear Degenerate Dynamic Models, Wroclaw University of Technology Publishing House, 2003.R.

• R. Iwankiewicz Dynamic Mechanical Systems under Random Impulses, World Scientific, Series on Advances in Mathematics for Applied Science, Vol. 36, 1995

For the past few years, in collaboration with The Land Forces Military Academy in Wroclaw, we have conducted research into laminate materials used for production of ballistic screens. Alongside these investigations works are conducted on fatigue crack growth in materials exposed to high-frequency cyclic loads. They are headed by Dr Mieczysław Szata and the results obtained hitherto are presented in monograph:

• M. Szata Description of Fatigue Crack Growth in its Energy Aspect, Wroclaw University of Technology Publishing House, 2002.

Towards the end of the 1960-ies (as mentioned above) on the basis of experimental research concerning analysis of stress and vibrations of constructions, investigations into constructing mathematical models were begun. It was then that the concept of the so-called multiple identification arose (1968, once again presented in the PAN [Polish Academy of Sciences] Bulletin 1977, Vol. 25. No 10), algorithmic procedures of empirical research methodology (1976) and new extended concepts of dimensional analysis (follow-up to research by Stefan Dobrot in 1954 begun once again by his former students).

Works similar to those presented above and dealing with measurement results processing by means of computers* *were also financed from Maria Sklodowska-Curie Fund (partners on the American side were professors E. Haug and V. Komkov).

Most important publications on those questions are:

• W. Kasprzak, B. Lysik *Selected Problems of Construction of Mathematical Model in Experiment Methodology,*Philosophical Studies, 1976 Y 20 No 2.

• W. Kasprzak, B. Lysik Dimensional Analysis: Algorithmic Procedures of the Experiment Control Scientific and Technical Publishing House, Warsaw 1988.

• W Kasprzak, B. Lysik On the Computer-Oriented Procedure for Dimensional Analysis. Bul. De L’Ac. Pol. Des Sci. Ser. Sci. Techn. 1974, Vol. 22 No 9 (see also Zentralblatt fur Matematik und ihre Grenzgebiete. Matematics 1975 Bd. 297)

Several other works have also been published which are not mentioned here, but presented in the textbook given above, and published by Scientific and Technical Publishing House, Warsaw. These were the achievements of the team which included, apart from those already mentioned, H. Hadryś, M. Kokar, P. Kozaczewski, W. Mejbaum, M. Rybaczuk, A. Sulkowski, M. Szata, J. Zaleski. All those works after the generalization of the fundamental theorem of dimensional analysis by Marek Rybaczuk who gives the representation of the invariant dimensional function also in relation to the revolution group in the three-dimensional space and fractal models were published in the following monographs:

• W. Kasprzak, B. Lysik, M. Rybarczyk Dimensional Analysis in the Identification of Mathematical Models, Singapore World Scientific, 1990.

• W. Kasprzak, B. Lysik, M. Rybaczek Measurements, Dimensions, Invariant Models and Fractals, Lviv Ukrainian Society on Fracture Mechanics, Wroclaw University of Technology Spolom Lviv 2004.

Both publications also quote from relevant sources [A. Sulkowski and Janusz Zaleski] an original method of testing the completeness of the set of entries in identification procedures. Investigations into mathematical models of these processes are continued under the supervision of professor Marek Rybarczuk and concern fractal models and cellular automatons. Here is the list of those who participate in these investigations:

Dr inż. Elżbieta Gabryś and dr inż. Dorota Aniszewska, mgr. inż. Piotr Kotowski (their works concern the application of fractals in fracture mechanics). The main results of these investigations are presented in the following publications:

• M. Rybaczuk The local form of dimensional functions. W: Similarity methods. 2nd International workshop. Eds Bernd Kroplin, Stephan Rudolph, Steffen Bruckner. Stuttgart, 25-26, November 1999. Stuttgart: Institut fuer Statik und Dynamik der Luft-und Raumfahrtkonstruktionen der Universitaet Stuttgart, cop. 1999 s. 261-276.

• M. Rybaczuk Dimensional analysis for fractals. W: Similarity methods. 3rd International workshop. [Eds Bernd Kroplin, Stephan Rudolph, Steffen Bruckner]. Stuttgart, 13./14. November 2000. [Stuttgart: Institut fuer Statik und Dynamik der Luft- und Raumfahrtkonstruktionen Universitaet Stuttgart], cop. 2000 s. 193-214.

• M. Rybaczuk, P. Stoppel The fractal growth of fatigue defects in materials, Int. J. Fract 2000 vol. 103 nr 1 pp. 71-94

• M. Rybaczuk The universal graph method. W: Similarity methods. 4th International workshop. [Eds. Bernd Kroplin, Stephan Rudolf, Steffen Bruckner]. Stuttgart, 5-6 November 2001. Stuttgart: Institut fuer Statik und Dynamik der Luft- und Raumkonstruktionen. Universitaet Stuttgart, cop. 2001 s. 189-219.

• A. Cetera The Minkowski dimension and critical effects in fractal evolution of defects, Chaos, Solitons & Fractals, vol. 12 pp. 475-482 (2000).

• A. Cetera , W. Błażejewski, Fractal characteristics of composite pipes defects in torsion testing, Int. J. Fract. vol. 113 nr 1 pp.. 253-265 (2002).

• P. Rupnowski , Calculations of J-integrals around fractal defects in plates, Int. J. Fract. vol. 111 nr 4 pp.. 383-394 (2001).

• D. Aniszewska , M. Rybaczuk , Analysis of the multiplicative Lorenz system, Chaos, Solitons & Fractals, 25, pp. 79-90 (2005).

• E. Gabryś, M. Rybaczuk , A. Kędzia , *Fractal models of circulatory system. Symmetrical and asymmetrical approach comparison, *Chaos, Solitons & Fractals, 24, pp 707-715 (2005).

• E. Gabryś , M. Rybaczuk, A. Kędzia , Blood flow simulation through fractal models of circulatory system., Chaos, Solitons & Fractals, 27, pp 1-7 (2006).

• D. Aniszewska , M. Rybaczuk, Physical stability and critical effects in models of fractal* defects evolution based on single fractal approximation, Chaos, Solitons & Fractals, (2006).

Professor M. Rybaczuk also developed models of biological systems based on fractal geometry (mainly of tissues connected with the human brain). These investigations were carried out in collaboration with the Department of Anatomy in Wroclaw Medical University. Their results were published in:

• A. Kędzia, M. Rybaczuk, J. Dymecki Fractal estimation of the senile brain atrophy. Folia Neuropathol. 1997 vol. 35 nr 4 pp. 237-240.

• A. Kędzia , M. Rybaczuk, J. Dymecki The fractal analysis of subdural haematoma. Folia Neuropathol. 2001 vol. 39 nr 3 pp. 203-207.

• A. Kędzia, M. Rybaczuk, R. Andrzejczak Fractal dimensions of human brain cortex vessels during the fetal period Med. Sci. Monit. 2002 vol. 3 nr 8 MT 46-51.

• M. Rybaczuk, A. Kędzia , L. Paradowski Fractal characteristics of brain vessel microangioarchitecture during the fetal period, Med. Sci. Monit, 2002 vol. 8 nr 8 MT 145-152.

• The results of these investigations were published jointly A. Kędzia, M. Rybaczuk Venous System of the Human Brain, Urban & Partner, Wroclaw 2004.

In 2005 this work won a collective Minister of Health Reward.

In the year 2000 investigations were undertaken, which were devoted to models of the observed sol-gel structures. Their results were published in:

• M. Grzegorczyk, M. Rybaczuk, K. Maruszewski, Ballistic aggregation: an alternative approach to modeling of silica sol-gel structures, Chaos, Solitons & Fractals 19, pp. 1003 1011(2004).
• M. Grzegorczyk, K. Maruszewski, M. Rybaczuk, Modeling of silica sol-gel thin films with ballistic aggregation, Chaos, Solitons & Fractals, 24, pp. 1053-1058 (2005).

In the1980-ies a large-scale research program was introduced which concerned materials fatigue (it should be noted that fatigue researches were initiated at the end of the 1950-ies by professor T. Porębski and professor M. Zakrzewski and devoted mainly to hypotheses about energy based on originally designed with relation to the level of knowledge at that time energy balance. That research was initially conducted by a two-person team: Rafał Błotny and Jerzy Kaleta. It has been continued up to the present day and carried out by professor Kaleta and his associates. The most interesting findings were published in:

• R. Błotny, J. Kaleta, Identification of the Fatigue Process Using an Energy Criterion. Stud. Geot. 1981 vol. 3 nr 1 pp. 45-56.

• R. Błotny, J. Kaleta, A method for determining the heat energy of the fatigue process in metals under uniaxial stress. P. 1. Determination of the amount of heat liberated from a fatigue-tested specimen. Int. J. Fatig. 1986 vol. 8 nr 1 pp. 29-33.

• R. Błotny, J. Kaleta Jerzy, W. Grzebień, W. Adamczewski, A method for determining the heat energy of the fatigue process in metals under uniaxial stress. P. 2. Measurement of the temperature of a fatigue specimen by means of thermovision camera-computer system. Int. J. Fatig. 1986 vol. 8 nr 1 pp. 35-38.

• J. Kaleta, R. Błotny, H. Harig, Energy stored in a specimen under fatigue limit loading conditions. J. Test. a. Eval. 1990 vol. 19 nr 4 pp. 326-333.

• J. Kaleta, Empirical foundations for formulating fatigue energy hypotheses. Habilitation Monograph. Wroclaw University of Technology, 1998 p. 144 (Scientific Research, Institute of Materials Science and Applied Mechanics no 59, Monographs ISSN 0324-9565; no 24)

• J. Kaleta, D. Kocańda, M. Skorupa, T. Topoliński, Empirical methods in materials and constructions fatigue. Fundamental research. Edited by Józef Szala. Bygdgoszcz: University Printing House. UTP. 2000.* *

Establishing precise possibilities of assessment of energy accumulated in the material taking account of cross effects called for undertaking research into constitutive relationships of the materials under investigation. Dr Grażyna Ziętek was the one to undertake them. Achievements in that field are presented in the following publications:

• G. Ziętek, Thermodynamics analysis of fatigue process. Studia Geotechnica et Mechanica. 1982 vol. 4, nr 1/2, s. 69-73.

• G. Ziętek The use of thermodynamics to analyse the hypotheses of fatique models of energy. Studia Geotechnica et Mechanica. 1982 vol. 4, nr 1/2, s. 59-67.

• J. Kaleta, G. Ziętek Representation of cyclic properties of austenitic steels with plasticity-induced martensitic transformation. Fatigue and Fracture of Engineering Materials and Structures. 1998 vol. 21, nr 8, s. 955-964.

• Ł. Maciejewski, W. Myszka, G. Ziętek, Identification and simulation of elasto-plastic deformation model. Materials Science Forum, 2005 vol. 482, s. 315-318

The works mentioned above and dealing with fractal models were carried out in order to obtain mathematical model in the field of fatigue and fracture mechanics of composite materials (see works by D. Aniszewska, W. Błażejewski, A. Cetera, P. Kotowski, P. Rupnowski, M. Rybaczuk, P. Stoppel).

Towards the end of the 1990-ies professor Jerzy Kaleta organized a large team of young scientists who undertook to work out a construction of systems built of materials characterized by controllable properties stimulated mainly by the magnetic field. In order to characterize these systems one also uses models of constitutive relationships developed by Ms Grażyna Ziętek. Significant successes of the team have brought it international renown and cooperation with foreign research centers. The following seminarians took part in the team’s work (in alphabetical order): J. Bomba, B. Fassa, A. Gasperowicz, P. Gąsior, K. Kaczmarek, P. Kijak, P. Kotowski, P. Kustroń, R. Mech, A. Mikołajczyk, K. Narbudowicz, D. Saniawa, P. Sawa, S. Susz, P. Wiewiórski, W. Wiśniewski, P. Zając, G. Ziętek, J. Żebracki. The achievements of the period are presented by works on magnetic materials from the Smart group and new non-destructive measurement methods (magnetovision used to measure the hysteresis loop and to detect the initial stadia of plastic deformations):

• J. Kaleta, D. Lewandowski, R. Mech, P. Gąsior, Magnetomechanical Properties of Terfenol-D Powder Composites. Solid State Phenomena, Smart Materials for Smart Devices and Structures, Vol. 154, 2009, pp. 35-40.

• J. Kaleta, D. Lewandowski, P. Wiewiórski, 3D Magnetovision Scanner as a Tool for Investigation of Magnetomechanical Principles. Solid State Phenomena, Smart Materials for Smart Devices and Structures, Vol. 154, 2009, pp.181-186.

• J. Kaleta, D. Lewandowski, Inelastic properties of magnetorheological composites: I. Fabrication, experimental tests, cyclic shear properties, Smart Materials and Structures, 2007, Volume: 16, pp. 1948-1953.

• J. Kaleta, D. Lewandowski, P. Zając, P. Kustroń, Magnetorheological composites as semi-active elements of dampers, J. Phys.: Conf. Ser. 149, 2009, 012092 (4pp).

• J. Kaleta, D. Lewandowski, G. Ziętek Inelastic properties of magnetorheological composites: II. Model, identification of parameters, Smart Materials and Structures, 2007, Volume: 16, pp. 1954-1960.

• J. Kaleta, J. Bomba, D. Lewandowski, P. Wiewiórski, Smart magnetic materials and magnetoresistive sensors in controlling of mechanical structures, Proceedings of SPIE, Vol. 6167, 2006.

• Kaleta, D. Lewandowski, P. Zając, Experimental identification of magnetorheological composites and elastomers properties. Mater. Sci. Forum, 2005 vol. 482, pp. 403-406.

• J. Kaleta Jerzy, S. Tumański, J. Żebracki, Magnetoresistors as a tool for investigating the mechanical properties of ferromagnetic materials. J. Magn. Magn. Mater. 1996 vol. 160 Jul pp. 199-200.

• J. Kaleta, J. Żebracki, Application of the Villari effect in fatigue examination of nickel. Zastosowanie efektu Villariego w badaniach zmęczeniowych niklu. Fatigue Fract. Eng. Mater. Struct. 1996 vol. 19 nr 12, pp. 1435-1443.

Another important subject of investigation were researches on materials with martensitic transformation induced by plastic deformation. The following works are worth a mention:

• Z. Mróz, G. Ziętek, *Modeling of Cyclic Hardening of Metals Coupled with Martensitic Transformation.*Archives of Mechanics. 2007 vol. 59
• z.* *Mróz, G. Ziętek. Two-surface model of Plastic Reinforcement Coupled with Phase Transformation and Cyclic Deformation. Acta Mechanica et Automatica. 2007 Vol. 1 No 1, p. 67-70.

In 1994 on the initiative of professor V.V. Panasyuk representing the Ukrainian Academy of Sciences and its Karpenko Institute in Lviv a tripartite collaboration was embarked upon (the third participant was Dresden University of Technology), whose aim was to organize Polish-German-Ukrainian Summer Schools on Fracture Mechanics. The first one took place in 1995. The latest the 10-th in 2007, the 11-th is supposed to take place this [2009] year. A complete history of these summer schools is presented in a publication edited by V.V. Panasyuk and W. Kasprzak entitled: Summer Schools on Fracture Mechanics Publishing House SPOLOM Lviv-Wroclaw 2007. Towards the end of the 1990-ies this collaboration was extended and several investigations were carried out jointly. The Polish side was represented by professor J. K. Kurzydłowski (Warsaw University of Technology) and Dr Mieczysław Szata with a team of PhD students. Their achievements have already been presented.

It was also in the 1990-ies that investigations into composites’ durability were started. As a result of them a new method of strengthening laminates with glass fiber (W. Błażejewski) for cylindrical pressure tanks was elaborated. Those researches bore fruit in the shape of a large international program whose chief objective was to use hydrogen as a fuel for mechanical vehicles. The Institute’s laboratory was also enriched with installations for high-pressure static and fatigue tests of pressure tanks. It is a unique on a European scale experimental stand controlling research conducted in the Institute, as well as controlling German and French teams which collaborate with us.

Periodically several other people apart from those listed in the present paper took part in the seminar’s activities. They presented plenty of interesting and original findings that have not been discussed as yet. The findings may not have concerned directly the very essence of the seminar’s interest but they have always been treated as valuable supplements to our research. This remark is directed in particular at interesting findings presented by professor Roman Galar, and used by the seminar participants as a tool in optimization tasks (mutation model and soft selection). The same is true in the case of works by professors Włodzimierz Kordylewski and Henryk Kudela showing new perspectives in examining the stability of dynamic processes. The seminarians are also indebted to professor Jan Zarzycki for his original studies and to prematurely deceased Dr Andrzej Gabor for his contribution, both of whom dealt with the problem of process filtration.

Practically from the word go three people have been taking part in the seminar activities taking care of the technical side of the venture i.e. instruments and apparatuses used in various experiments, and on several occasions performing measurements, these are:

• Mgr. inż. Karol Baranowski
• Inż. Wiesław Ćmikiewicz
• Jan Orłowski.

Without their inventiveness and support a lot of our achievements would be virtually unattainable.