Materiały konferencyjne, referaty (WM)
Stały URI dla kolekcjihttp://hdl.handle.net/11652/163
Przeglądaj
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 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 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 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 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 Drive-by-wire of a converted into electric car Syrena 105 enabling Hardware-In-Loop tests of driving(Wydawnictwo Politechniki Łódzkiej, 2021) Adamski, Paweł; Olejnik, PawełIn this work, replacing an electronic throttle pedal and a driver in an electric car converted into electric by a hardware-in-loop workbench is described, highlighting the advantage of drive-by-wire feature that appeared after conversion. Drive-by-wire facilitates replacing a driver by Hardware-In-Loop (HIL) workbench, as instead of simulating a mechanical pedal depression by a servomechanism, electric signals can be transmitted directly from the workbench. Thanks to one-pedal-driving feature of the motor controller used in the car, there is a possibility of performing a variety of road tests replacing only the electronic throttle pedal. Hardware interventions in the car are described and sample HIL test results are presented.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 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 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 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 Design and simulation of a lower limb exoskeleton with linear electric actuators(Wydawnictwo Politechniki Łódzkiej, 2021) Grzelczyk, Dariusz; Jarzyna, Olga; Awrejcewicz, JanIn the present study, we proposed and investigated a relatively simple and inexpensive construction of a lower limb exoskeleton driven by linear electric actuators and controlled by an Arduino microcontroller board. Moreover, to study crucial kinematic and dynamic parameters of the proposed device, we developed a general, three-dimensional simulation model of the exoskeleton in Mathematica software. To control individual joints of the investigated exoskeleton, we employed time histories of human joint angles in normal gait, recorded with the use of a motion capture system. As a result, we developed a novel human gait generator, which can be used to produce rhythmic movements in hip, knee and ankle joints of both limbs. Finally, the developed control approach was verified with the use of the constructed prototype of the exoskeleton.Pozycja Mathematical Modelling of an extended Swinging Atwood Machine(Wydawnictwo Politechniki Łódzkiej, 2021) Yakubu, Godiya; Olejnik, Paweł; Awrejcewicz, JanAn extended model for a variable-length pendulum’s mechanical application is being derived from the Swinging Atwood Machine (SAM). An electrical component consisting of an electromagnet and armature coil is attached on the link connected to the counterweight mass on the left-hand side of the modified SAM to provide an excitation force for the system when an electric current is induced. The extended SAM presents a novel SAM concept being derived from a variable-length double pendulum with a suspension between the two pendulums. The equations of motion are simulated to see the trajectory of the two pendulums. The results of original numerical simulations show some compact regions of attraction at some regimes. Therefore, the extended SAM’s nonlinear dynamics presented in the current work can be thoroughly studied, and more modifications can be achieved. The new technique can reduce residual vibrations through damping when the desired level of the crane is reached. It can also be used in simple mechatronic and robotic systems.Pozycja Geometrically nonlinear vibrations of double-layered nanoplates(Wydawnictwo Politechniki Łódzkiej, 2021) Awrejcewicz, Jan; Mazur, OlgaThe geometrically nonlinear vibrations of simply supported double-layered graphene sheet systems are considered in the presented manuscript. The interaction between layers is taken into account due to van der Waals forces. The investigation is based on the nonlocal elasticity theory, Kirchhoff plate theory and von Kármán theory. The governing equations are used in mixed form by introducing the stress Airy function. The analytical presentation of the nonlinear frequency ratio for in-phase vibration and anti-phase vibration modes is presented. It is shown that the nonlocal parameter included in the compatibility equation can significantly change the vibrating characteristics.Pozycja Determination of global damping and stiffness coefficients of journal foil bearing(Wydawnictwo Politechniki Łódzkiej, 2021) Łagodziński, Jakub; Tkacz, Eliza; Kozanecki, ZbigniewFor the few last years, in modern low-power generation systems, a demand for oilfree compressors has appeared. The development of reliable bearing technology for this relatively high-speed small turbomachinery could be crucial. In order to implement this technology more widely, a selection of the optimal design from the viewpoint of machine reliability must be conducted. A high speed turbomachinery with nominal speed of tens of thousands rpm strongly depends on the proper rotordynamic design. This is especially important when the foil bearings are taken to consideration. These compliant surface gas bearings are a class of hydrodynamic bearings that use the ambient gas as their working fluid and, thus, require no dedicated lubrication system. On the other hand, due to their relatively low damping, a designer should analyze thoroughly the dynamics of the rotor-bearing-casing system in the whole operating rpm range. A correctly operating rotor supported in foil bearings is a design solution that have wide possibilities of applications, unavailable for conventionally supported one. In the turbomachinery, a dynamic behaviour of the machine is related mostly to the stiffness and damping coefficients of system components like rotor, bearings and casing. The foil bearings, although simple in design, indicate complex behaviour resulting from Coulomb friction between their elements. This Coulomb friction affects the damping and stiffness of a given bearing support. Gas film, as a bearing part with relatively high stiffness, plays less role in the rotordynamics than the elastic structure of corrugated foils. So far, many more or less reliable numerical models of this phenomenon have been built and their experimental verification results have been described in literature. The research approach presented in this paper is different. The authors suggested obtaining the data experimentally from the bearing isolated on a test bench, where, the shaft is stationary (fixed), and the gas film is not present. The shaker excites the bearing sleeve while the damping and stiffness are provided to the system by the foil structure. The test bench can be described mathematically as system with single degree of freedom with damping and external forcing. The information collected about the bearing’s global coefficients can be implemented afterwards to the rotordynamic software as a tabular data. This will allow to prepare reliable models that will shorten the design process of newly developed compressors with these oilfree supports.Pozycja Research of the dynamics of a physical pendulum forced with an electromagnetic field(Wydawnictwo Politechniki Łódzkiej, 2021) Ogińska, Ewelina; Grzelczyk, Dariusz; Awrejcewicz, JanIn this paper, both experimental and numerical results of the dynamics of a pendulum with a neodymium magnet and an aerostatic bearing are presented. The experimental stand includes the pendulum with the neodymium magnet at the end of the rod, whereas four electric coils are placed underneath. The pivot of the pendulum is supported on the aerostatic bearing. As a result, dry friction resistance in the pivot joint can be negligible and it has only a viscous character. The electric current with a given frequency and duty cycle and of a square waveform flows through the coils. Interaction between the neodymium magnet and the electric coils leads to the forced angular motion of the pendulum with the neodymium magnet. Both mathematical and physical models with experimentally confirmed system parameters are derived. The results of the simulation and experiment showed rich dynamics of the system, including various types of regular motion (multi-periodicity) and chaos.Pozycja Dynamic analysis of functionally graded sandwich shells resting on elastic foundations(Wydawnictwo Politechniki Łódzkiej, 2021) Tetyana, Shmatko; Lidiya, Kurpa; Awrejcewicz, JanFree vibrations of sandwich shallow shells resting on elastic foundations are investigated. It is assumed that shell consists of three layers of the different thickness. Different schemes of arrangement of layers are considered. Namely, the core is made of ceramics or metals , and the upper and lower layers are made of FGM. The volume fractions of metal and ceramic are described by the power law. Shear deformation shell theory of the first (FSDT) that includes interaction with elastic foundations is applied. To study shells with an arbitrary plan form the R-functions theory combined with the variational Ritz method are used. Validation of the proposed method and developed software has been examined on test problems for FG shell with rectangular plan form. New results for shallow shells with complex plan form were obtained. Effects of the power law index, boundary conditions, thickness of core and face sheet layers, elastic foundations on fundamental frequencies are studied in this work.