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Pozycja Antykorozyjne warstwy nanokrystalicznego diamentu na implantach medycznych(Politechnika Łódzka, 2000) Bąkowicz, K.; Grabarczyk, J.; Niedzielski, P.; Mitura, S.Pozycja Mikroskopia fluorescencyjna (MF) i elektronowa mikroskopia skaningowa (SEM) w badaniu biofilmu bakteryjnego(Wydawnictwo SIGMA-NOT, 2006) Jakubowski, Witold; Klimek, Leszek; Szymański, Witold; Walkowiak, BogdanW ciągu ostatnich lat niezwykle dynamicznie rozwijają się nauki łączące zagadnienia medyczne i inżynierskie. Jednym z efektów obserwowanego postępu jest coraz szerszy zakres wykorzystania biomateriałów wspomagających funkcje życiowe pacjenta. Obecnie medycyna dysponuje materiałami o odpowiedniej charakterystyce fizykochemicznej, a także wysokiej biozgodności. Wciąż jednak obecność implantów może być przyczyną oportunistycznych infekcji bakteryjnych. Bakterie mogą kolonizować sztuczne elementy, tworząc na ich powierzchni wielowarstwowy biofilm. W tej postaci skutecznie opierają się działaniu układu odpornościowego oraz antybiotyków i stają się źródłem wielu zakażeń. Praca przedstawia porównanie dwóch metod obserwacji bakterii na powierzchniach implantów, wskazując na zalety i ograniczenia stosowania mikroskopii fluorescencyjnej i elektronowej mikroskopii skaningowej.Pozycja Skrobia modyfikowana plazmochemicznie jako wypełniacz materiałów polimerowych(Wydawnictwo SIGMA-NOT, 2006) Szymanowski, Hieronim; Kaczmarek, Mariusz; Gazicki-Lipman, Maciej; Klimek, Leszek; Szumigaj, JoannaW badaniach użyto skrobi ziemniaczanej jako wypełniacza dla polietylenu (LDPE) w celu zwiększania jego zdolności do biodegradacji. Ponieważ mieszalność skrobi natywnej z polietylenem jest słaba, jej ziarna poddano plazmochemicznej obróbce metanem. Zmodyfikowany w ten sposób wypełniacz wykazuje mniejszą hydrofilowość i znacznie większą dyspersję w matrycy LDPE. Właściwości mechaniczne takich materiałów kompozytowych są gorsze od czystego polietyleny, ale lepsze niż w przypadku LDPE wypełnionego skrobią niemodyfikowaną. Przeprowadzone badania mikrobiologicznym i przy pomocy elektronowego mikroskopu skaningowego (SEM) wykazały znacząco lepsze właściwości biorozkładu mieszanek skrobia modyfikowana/polietylen niż czystego polietylenu.Pozycja Efekty degradacji folii opakowaniowych przez mikroflorę termofilną(Wydawnictwo SIGMA-NOT, 2006) Szumigaj, Joanna; Żakowska, Zofia; Klimek, Leszek; Bartkowiak, ArturBadano podatność folii opakowaniowych otrzymanych z celulozy, polikaprolaktonu i polikwasu mlekowego na działalność glebowej mikroflory termofilnej. Po 2 miesiącach kompostowania w temperaturze 48°C przeprowadzono analizę mikrobiologiczną powierzchni folii i wyniki porównano z analizą ilościową mikroflory mezofilnej kolonizującej folie. Liczba mikroflory termofilnej była o rząd lub dwa rzędy wielkości większa niż ilość mikroflory mezofilnej. Dominującą mikroflorą termofilną były szczepy bakterii Bacillus oraz pleśni Aspergillus fumigatus. Na podstawie obserwacji mikroskopowych stwierdzono, że proces biodegradacji folii przez mikroflorę termofilną przebiegał efektywniej i szybciej.Pozycja Fundusze strukturalne UE dla zrównoważonego rozwoju w regionie łódzkim([Wydawnictwo Politechniki Łódzkiej], 2010) Jóźwik, KrzysztofPozycja Metrologia w technikach wytwarzania. Część 2(Politechnika Łódzka, 2014) Kruszyński, Bogdan; Jóźwik, Krzysztof; Dobosz, Marek; Gawlik, Józef; Grzesik, Wit; Jakubiec, Władysław; Jóźwik, Krzysztof; Kruszyński, Bogdan; Łukianowicz, Czesław; Marciniak, Tadeusz; Olczyk, Aleksander; Pałko, Tadeusz; Pawlus, Paweł; Płaska, Stanisław; Ratajczyk, Eugeniusz; Skoczylas, Leszek; Sładek, Jerzy; Staniek, Roman; Wieczorowski, Michał; Wójcik, Ryszard; Żebrowska-Łucyk, SabinaPozycja Metrologia w technikach wytwarzania. Część 1(Politechnika Łódzka, 2014) Kruszyński, Bogdan; Jóźwik, Krzysztof; Dobosz, Marek; Gawlik, Józef; Grzesik, Wit; Jakubiec, Władysław; Jóźwik, Krzysztof; Kruszyński, Bogdan; Łukianowicz, Czesław; Marciniak, Tadeusz; Olczyk, Aleksander; Pałko, Tadeusz; Pawlus, Paweł; Płaska, Stanisław; Ratajczyk, Eugeniusz; Skoczylas, Leszek; Sładek, Jerzy; Staniek, Roman; Wieczorowski, Michał; Wójcik, Ryszard; Żebrowska-Łucyk, SabinaPozycja Metrologia w technikach wytwarzania. Część 3(Politechnika Łódzka, 2014) Kruszyński, Bogdan; Jóźwik, Krzysztof; Dobosz, Marek; Gawlik, Józef; Grzesik, Wit; Jakubiec, Władysław; Jóźwik, Krzysztof; Kruszyński, Bogdan; Łukianowicz, Czesław; Marciniak, Tadeusz; Olczyk, Aleksander; Pałko, Tadeusz; Pawlus, Paweł; Płaska, Stanisław; Ratajczyk, Eugeniusz; Skoczylas, Leszek; Sładek, Jerzy; Staniek, Roman; Wieczorowski, Michał; Wójcik, Ryszard; Żebrowska-Łucyk, SabinaPozycja Identification of the model parameters based on the ambiguous branches of resonance response curves(Wydawnictwo Politechniki Łódzkiej, 2021) Sypniewska-Kamińska, Grażyna; Awrejcewicz, JanA concept of the method of determining the parameters describing the damping and the nonlinearity, which can be of physical or geometrical nature, is presented in the paper. The main idea is explained regarding mechanical systems with one degree of freedom, however, the method can be also employed to identification for systems with two DoF provided that the couplings are weak and the resonances do not occur simultaneously. The analysis of stationary resonance states can be reduced only then to the third-degree equation, which is a necessary condition for the applicability of this method. Numerical simulations, which are carried out, confirm the usefulness and accuracy of the method.Pozycja Construction and 3D model of stand for investigating a non-ideal forcing in a nonlinear chain dynamics of self-excited oscillators with friction(Wydawnictwo Politechniki Łódzkiej, 2021) Rogala, Patryk; Olejnik, Paweł; Awrejcewicz, JanThe research involves application and research on a non-ideal forcing to modelling and identification of vibrating systems with friction. It is still an innovative approach in the numerical analysis of vibrations of mechatronic machines and devices. This will allow to make a much real numerical modelling and more efficient identification of nonlinear dynamic phenomena observed in vibrating systems with friction, and thus, a better modelling of such phenomena in computer programs. To obtain the goal, initial 3D model of the mechanical stand was made in the CAD software. Based on the 3D model, real stand will be built, and experiments will be held to obtain data that will be necessary to ensure correctness of the mathematical model, which also will be studied and developed.Pozycja Modelling and Analysing of a Spring Pendulum Motion in the Presence of Energy Harvesting Devices(Wydawnictwo Politechniki Łódzkiej, 2021) Abohamer, M. K.; Awrejcewicz, J.; Starosta, R.; Amer, T.S.; Bek, M.A.Energy harvesting will become more and more essential mechanical vibration applications of many devices. The vibrations can be converted by appropriate devices into electrical energy, which can be used as a power supply instead of ordinary ones. This paper investigates a dynamical system associated with two devices: a piezoelectric device and an electromagnetic one. These devices are connected with a nonlinear damping spring pendulum with 2DOF, in which its supported point moves in a circular path. The equations of motion are obtained using Lagrange’s equations of the second kind. The asymptotic solutions of these equations are obtained up to the third approximation utilizing the perturbation approach of multiple scales. The comparison between these solutions and the numerical ones reveals high consistency between them. The steady-state solutions are obtained, and their stabilities are tested. The influences of the excitation amplitudes, the damping coefficients, and the different frequencies on energy harvesting devices outputs are examined and discussed. The work is essential due to its significance in real-life applications. The developed methodology and obtained results can be useful in various applications like power supply of sensors and charging electronic devices.Pozycja Influence of a relatively high frequency structure vibrations on the dynamics of real stick-slip motion(Wydawnictwo Politechniki Łódzkiej, 2021) Olejnik, Paweł; Górniak vel Górski, Adrian; Cebulak, Maciej; Awrejcewicz, JanThe work concerns the research on the impact of structure vibrations on the dynamics of frictional contact of bodies moving in relation to each other and remaining in frictional contact, causing a stick-slip motion. A literature review was carried out, describing mainly the phenomena concerning friction, but also the dynamics of vibrations and non-ideal energy sources that induce system oscillations. In the next step an experimental station for investigation of friction equipped with a new subsystem inducing high-frequency vibrations is presented to propose a modified physical model of the investigated frictional system. After analysing the most important factors influencing the behavior of the tested system, a mathematical description was prepared, which in theory showed the potential influence of the attached subsystem on the dynamics of the movement of the tested object - the frictional connection. Various methods of implementing the unbalance of rotors, being the source of highfrequency excitation, have been considered. At the final stage, a series of measurements of the displacement of the vibrating block on the moving belt was performed with the highfrequency excitation turned on and off. The prepared graphs were used to analyse the dynamics of frictional contact and the impact of non-autonomous vibrations on the occurrence of the stick-slip phenomenon.Pozycja Vibration of the system with nonlinear springs connected in series(Wydawnictwo Politechniki Łódzkiej, 2021) Awrejcewicz, Jan; Starosta, Roman; Sypniewska-Kamińska, GrażynaSolution of the problem and qualitative analysis of the forced vibration of the spring pendulum containing nonlinear springs connected in series is made in the paper. The method of multiple scales in time domain (MMS) has been employed in order to carry out the analytical computations. The MMS allows one, among others, to predict the resonances which can appear in the systems. The approximate solution of analytical form has been obtained for vibration at main resonance.Pozycja Magnetic oscillator under excitation with controlled initial phase(Wydawnictwo Politechniki Łódzkiej, 2021) Polczyński, Krystian; Bednarek, Maksymilian; Awrejcewicz, JanThe work contains the results of numerical simulations of the dynamics of a magnetic pendulum system subjected to excitation with a varying initial phase. A magnetic pendulum consists of a magnet fixed to the end of its arm and an electric coil below it. The initial phase of the excitation is presented as a linear function of the dynamic variable of the system, which is the angular position of the pendulum. The obtained basins of attraction indicate the occurrence of multi-periodic solutions in the system depending on the changes in the parameters of this system. The periodicities of the observed solutions are quantified mostly by odd numbers.Pozycja Estimation the Domain of Attraction for a System of Two Coupled Oscillators with Weak Damping(Wydawnictwo Politechniki Łódzkiej, 2021) Awrejcewicz, Jan; Puzyrov, Volodymyr; Losyeva, Nataliya; Savchenko, Nina; Nikolaieva, OksanaWhen solving a wide class of problems of nonlinear dynamics, the stability property of a given system regime is a prerequisite for design. An important role is played by the concept of the domain of attraction (DoA) of the equilibrium point (or limit cycle). However, as a rule, this domain is difficult to find and describe in explicit form. Therefore, the search for DoA estimate has been a fundamental problem in the control theory since the middle of the last century. Currently, methods based on Lyapunov functions predominate in the literature. We have studied the problem of obtaining the estimates of the DoA for equilibrium of the mechanical systems. The method for using Lyapunov function of special kind for a system with polynomial right-hand side to find the estimates for DoA is proposed. This procedure is illustrated by the example of a mechanical system which consists of two coupled nonlinear oscillators with weak damping.Pozycja Higher order asymptotic homogenization for dynamical problems(Wydawnictwo Politechniki Łódzkiej, 2021) Awrejcewicz, J.; Andrianov, I.I.; Diskovsky, A.A.In general, asymptotic homogenization methods are based on the hypothesis of perfect scale separation. In practice, this is not always the case. The problem arises of improving the solution in such a way that it becomes applicable if inhomogeneity parameter is not small. Our study focuses on the higher order asymptotic homogenization for dynamical problems. Systems with continuous and piecewise continuous parameters, discrete systems, and also continuous systems with discrete elements are considered. Both low-frequency and highfrequency vibrations are analyzed. For low-frequency vibrations, several approximations of the asymptotic homogenization method are constructed. The influence of the boundary conditions, the system parameters is investigated.Pozycja Anisotropic friction sliding rule influence on the mechanical systems dynamics(Wydawnictwo Politechniki Łódzkiej, 2021) Wijata, Adam; Stańczyk, Bartosz; Awrejcewicz, JanAnisotropic friction can produce friction force which is not collinear with a sliding direction. How much friction deviates from a sliding direction is described with a so-called sliding potential or equivalently a sliding rule. A sliding potential is often described with an ellipse or a superellipse. In this paper we propose an oval curve which provides piecewise continuous mathematical description for a sliding rule and fits better to the experimental results than a typical superepllipse. For an exemplary mechanical system it is shown, that an anisotropic sliding potential can lead to an unstable equilibrium position in the system. Furthermore, for what parameters the unstable equilibrium occurs differs between sliding potential models. We have tested four different geometrical models of sliding potential in this regard.Pozycja Influence of fractional order parameter on the dynamics of different vibrating systems(Lodz University of Technology Press, 2021) Zafar, Azhar Ali; Awrejcewicz, JanIn this work, we will investigate the fractional differential equations associated to different vibration phenomena. More specifically, we will discuss Bagley-Torvik equation, composite fractional relaxation differential equation and the motion of a linear oscillator using fractional derivative operator in the sense of Atangana-Baleanu. In order to be consistent with the physical systems the value of the fractional parameter that characterizes the existence of fractional structures in the system, lies within unit interval. The solutions of the non-integer order differential equation are obtained and expressed in terms of generalized functions depending upon the fractional parameter. The classical cases could be recovered by making the limit of fractional parameter approaches to unity. Moreover, we will analyze and compare the control of the fractional order parameter on the dynamics of the models and useful conclusions are recorded.Pozycja Thermal waves in composite membrane with circular inclusions in hexagonal lattice structures(Wydawnictwo Politechniki Łódzkiej, 2021) Andrianov, I.V.; Awrejcewicz, J.; Starushenko, G.A.; Kvitka, S.A.Non-stationary heat conduction in the fibre composite materials is studied. 2D сomposite media consists of matrix with circular inclusions in hexagonal lattice structures. The perfect contact between different materials is assumed on the boundary of the fibres. The local temperature field in the unit cell is modeled by the heat equation. Time variable excludes from the original boundary value problem using of Laplace transform. Asymptotic homogenization method allows to reduce original problem for multiply-connected domain to the sequence of boundary value problems in simply-connected domains. Composite material is supposed densely-packed with a high-contrast. In this case, the local boundary value problem includes a small parameter equal to the ratio of the distance between the inclusions to the characteristic cell size. Using of additional small parameter and thin layer asymptotics allows to solve local problem analytically. Closed form expression for effective heat conductivity is obtained.Pozycja Energy flow control in a system of coupled pendulums using magnetic field(Wydawnictwo Politechniki Łódzkiej, 2021) Pilipchuk, Valery; Polczyński, Krystian; Bednarek, Maksymilian; Awrejcewicz, JanIn the presented work, we proposed a methodology of controlling the resonance energy exchange in mechanical systems by creating appropriate electromagnetic fields around the system’s structural subcomponents. It has been shown theoretically and confirmed experimentally that properly guided magnetic fields can effectively change mechanical potentials in such a way that the energy flow between the oscillators takes the desired direction. In particular, a model of two weakly coupled pendulums subjected to an electromagnetic load using a specific set of descriptive functions was considered. The developed control strategies are based on the observation that, in the case of antiphase oscillation, the energy is moving from the pendulum, which is in the repelling magnetic field, to the oscillator not subjected to magnetic field. The advantage of the suggested control strategy is that the temporal rate of inputs is dictated by the speed of beating, which is relatively slow compared to the carrying oscillations.