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1
Content available remote A Rotationally Periodic Continuous Analog Model for Bladed Disk Assembly Vibration
100%
Krzyżyński T.
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tom Vol. 20
167-179
EN
A rotationally periodic continuous analog model is considered in order to enhance the understanding of the vibratory response of bladed disk assembly. The analogy uses a series of transversely and longitudinally vibrating continuous segments. The segments are arranged in a rotationally periodic pattern, with coupling between each other accomplished by suspension elements. Analytical expressions for the system eigenfrequencies and eigenfunctions are found. Results in the case of free vibrations of a perfect periodic system are presented.
2
Content available remote The Optimization Problem in Spectroscopic Ellipsometry Technique : Optical Spectra Determination for Pb5Ge3O11 Crystal
63%
Dorywalski K. , Krzyżyński T.
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tom Vol. 39, No. 4
21-30
EN
Ellipsometric spectra Ψ(λ), ∆(λ) was measured for Pb₅Ge₃O₁₁ optical crystal in the spectral range 388-620 nm. Mathematical model was developed taking into account optical anisotropy and surface roughness of the measured specimen. Nonlinear regression method was applied in order to fit experimental and modeled data. Refractive index spectra no(λ) ne(λ) are determined for Pb₅Ge₃O₁₁ single crystal for ordinary and extraordinary light beams. Ellipsometric spectra Ψ(λ), ∆(λ) was measured for Pb₅Ge₃O₁₁ optical crystal in the spectral range 388-620 nm. Mathematical model was developed taking into account optical anisotropy and surface roughness of the measured specimen. Nonlinear regression method was applied in order to fit experimental and modeled data. Refractive index spectra no(λ) ne(λ) are determined for Pb₅Ge₃O₁₁ single crystal for ordinary and extraordinary light beams.
3
Content available remote Identyfikacja obiektu wibroakustycznego za pomocą modeli nieparametrycznych
63%
Błażejewski A. , Krzyżyński T.
Advances in Materials Science
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2008
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tom Vol. 8, nr 2(16)
5-11
PL
W pracy przedstawiono przykład identyfikacji obiektu wibroakustycznego na przykładzie głośnika niskotonowego zestawu głośnikowego ALTUS. Zaprezentowano opis badanego obiektu za pomocą trzech modeli nieparametrycznych: transmitancji widmowej, funkcji korelacji oraz gęstości widmowej.
4
Content available remote Selection Methodology of Vibro-Isolation Properties of Seat Suspension Systems
63%
Maciejewski I. , Krzyżyński T.
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tom Vol. 33, No. 1
89-100
EN
In this paper a selection methodology of vibro-isolation properties of seat suspension systems is presented. The investigated passive suspension system has vibro-isolating properties that are shaped by a change of forces in a pneumatic spring and hydraulic damper. A combined optimisation procedure has allowed to find the Pareto-optimal system configuration with simultaneous minimization of conflicted optimisation criteria: the suspended body acceleration and suspension travel.
5
Content available remote On Mechanics and Control of Six-Legged Walking Robot
63%
Szczebiot R. , Krzyżyński T.
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tom Vol. 24, No. 1
185-197
EN
In the paper fundamentals of mechanics and control of six-legged mobile robot are presented. Several construction aspects of robot legs are considered. An analysis of motion and structure of a robot leg, its kinematics and drive system is carried out. Some details concerning robot body are given. A robot control system aimed at steering the legs of the walking machine and monitoring their position, as well as monitoring surroundings of the robot by means of external sensors is investigated in details. The robot presented in the paper has been conceived, designed and made as a prototype machine with an open construction. This makes any modification possible and easy.
6
Content available remote A simple model of sound in enclosures with a low frequency harmonic excitation
63%
Błażejewski A. , Krzyżyński T.
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tom Vol. 25
77--82
EN
In the paper the problem of a room with a sound source inside is investigated. The effect, an acoustic field inside is affected by two factors: the shape and the boundaries of the enclosure. In order to evaluate the acoustic field, modal analysis assumption has been applied to describe the room's pressure distribution. Thus, the sum over a set of the room's eigenfunctions and proper time components represents the values of the acoustic field. Eigenfunctions can be obtained by solving the Helmholtz equation for rigid walls. Time components can be determined applying Green’s theorem. This approach allows boundary conditions to be adjoined to time components and thereafter obtain a set of ordinary differential equations for each specified time component correlated with corresponding eigenfunction. Assuming a harmonic excitation, time components are harmonic as well. Therefore, the values of coefficients of each time component (i.e. the modal amplitudes) are required. Directly, one can evaluate the modal amplitudes by solving simple algebraic equations. As a result of this calculation, the finite set of eigenfunctions of an enclosure and modal amplitudes has been obtained. In this case of an additional assumption of high enough boundary impedance, the modal coupling can be neglected and consecutive formula reduction is possible. Under frequency limitation, the modal approach to a room's acoustic field modelling, involves much less computational effort than the alternative, for instance applying Finite Element Method (FEM) or Boundary Element Method (BEM).
7
Content available Uogólniony model układu redukcji drgań stosowanego do ochrony operatorów maszyn roboczych
63%
Maciejewski I. , Krzyżyński T.
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tom R. 22, nr 12
982--986, CD
PL
Praca ma na celu zaproponowanie uogólnionego modelu układu redukcji drgań w zastosowaniu do ograniczania szkodliwego wpływu wibracji na operatorów maszyn roboczych. W niniejszej pracy skoncentrowano się na układach drgających obsługiwanych przez człowieka, dla których rozpatrywany układ wibroizolacji powinien skutecznie redukować drgania w całym zakresie częstotliwości wymuszeń. Opracowano uogólniony model układu wibroizolacji, którego nieliniowe charakterystyki należy dobrać specjalnie dla danego wymuszenia ruchu drgającego.
EN
The aim of this paper is to propose a generalised model of the vibration reduction system in order to protect the working machine operators against vibration. This work concentrates on the vibrating systems used by human and for whose the designed vibro-isolators should efficiently reduce the vibrations in whole frequency range of the excitation signal. The general model of vibration isolation system is elabo-rated and its non-linear characteristics should be se-lected especially for the given excitation.
8
Analiza obciążenia dynamicznego oraz drgań mechanicznych w technicznych środkach transportu w aspekcie ochrony organizmu kierowcy
63%
Pliszko M. , Krzyżyński T.
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tom nr 3
CD-CD
PL
Praca zawiera opis wpływu drgań mechanicznych na organizm człowieka. Przedstawiona jest wartość skuteczna, która jest miarą oddziaływania drgań mechanicznych na organizm człowieka w pojeździe. Opisane zostały również modele obliczeniowe pojazdu dla drgań swobodnych oraz drgań wymuszonych. Przedstawiono odpowiednio modele fizyczne i matematyczne wyżej wymienionych obciążeń dynamicznych. W pracy zawarto również opis głównej przyczyny powstawania drgań mechanicznych i akustycznych jaką są nierówności drogi.
EN
The object of simulation is the mathematical model of vehicle with a suspension system. Model contains free vibrations and forced vibrations. The paper describes sources of vibrations, especially vibrations from unevenness of roads. Mathematical equations describe vibrations in front and in the back of vehicle. Equations of the motions are useful to calculate vibration level and evaluate vibrations.
9
Content available remote Modelling and control optimization of the electromagnetic motor using genetic algorithm
63%
Pecolt S. , Krzyżyński T.
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tom Vol. 24
319--324
EN
The paper deals with the problem of implementing a genetic algorithm GA to calculate a pareto-optimal function of voltage powering solenoids, used for controlling a linear electromagnetic motor. The process assumes two conflicted criteria: minimizing the time of motion of the linear electromagnetic motor (l.e.m.) and minimizing the energy input. The results have been obtained for a set position with a narrow range of power supply. The work of electromagnetic motor is based on a electromagnetic repulsion. The device consists of a two solenoids and a slide control with neodymium magnet bars placed on its end. The paper discusses also static characteristics of l.e.m., i.e. a current density vs. force, a dependence of a force on deplacement of the slide control and magnetic flux density. There are also dynamic characteristics of l.e.m. presented and compared to the results of simulations obtained in the Matlab-simulink program.
PL
W pracy przedstawiono sposób implementacji algorytmów genetycznych do wyznaczania pareto-optymalnych funkcji sterujących, służących do sterowania pozycją suwaka siłownika elektromagnetycznego. Proces zakłada minimalizację dwóch przeciwstawnych kryteriów, tj. czasu ruchu tłoka siłownika i energii pobranej przez urządzenie. Praca siłownika elektromagnetycznego oparta jest o zasadę wypychania magnesów stałych z pola magnetycznego solenoidów. Urządzenie składa się z dwóch solenoidów i suwaka na którego końcach są umieszczone magnesy stałe. W pracy przedstawiono charakterystyki statyczne jak i dynamiczne urządzenia, m.in. zależność prądu od siły wypychającej magnes, zależność siły od pozycji magnesu w solenoidzie.
10
Content available Simulation of trajectory of an aircraft seat ejection
63%
Głowiński S. , Krzyżyński T.
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tom Vol. 1, nr 4
343-351
EN
The paper deals with modeling and simulation of motion trajectory of an ejection seat in the training-combat aircraft TS-11 "Iskra". The ejection seat and its operation are characterized. Mathematical and computer models are elaborated with the help of MATLAB-Simulink applications. Additionally, simulations are conducted for various velocities of the aircraft.
PL
W artykule przedstawiono dynamikę fotela katapultowego o nazwie SK na podstawie odrzutowego szkolno-bojowego samolotu TS-11 "Iskra". Scharakteryzowano fotel katapultowy i zasadę jego działania. Opracowano model matematyczny oraz komputerowy obiektu przy wykorzystaniu programu MATLAB – Simulink i przeprowadzono symulację przy różnych prędkościach lotu.
11
Content available Modelowanie układu zawieszenia siedziska stosowanego do ochrony operatorów maszyn roboczych przed drganiami w poziomym kierunku oddziaływania
63%
Maciejewski I. , Krzyżyński T.
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tom R. 22, nr 12
977--981, CD
PL
W pracy przedstawiono sposób tworzenia modelu układu zawieszenia wraz z biomechanicznym modelem ciała ludzkiego w pozycji siedzącej. Zademonstrowano ponadto małą skuteczność redukcji drgań mechanicznych w przypadku użytkowania układów zawieszeń siedzisk opracowywanych dla poziomych kierunków oddziaływania. Opracowane w ramach niniejszej pracy modele posłużą do przeprowadzenia analizy oddziaływań dynamicznych w układzie operator-maszyna oraz wspomogą proces doboru właściwości wibroizolacyjnych układów zawieszeń do specyficznych warunków pracy.
EN
In this paper a computer model of the seat suspension system for one direction of the horizontal vibration influence is presented and the system dynamic properties are investigated under laboratory conditions. The characteristics describing principal forces in the system are evaluated experimentally, while the system dynamics is tested using three different vibration intensities that affect the human body in a sitting position. In the basis of vibration acceleration, the power spectral densities and transmissibility functions are evaluated and then the simulation and measurement results are compared.
12
Content available Control design of semi-active seat suspension systems
63%
Maciejewski I. , Krzyżyński T.
Journal of Theoretical and Applied Mechanics
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2011
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tom Vol. 49 nr 4
1151-1168
EN
The paper deals with the control design of semi-active seat suspension systems. A semi-active vibration control strategy basing on the inverse dynamics of a spring or damper element and a primary controller is studied. The optimisation procedure proposed in the paper makes it possible to calculate controller settings and these, in turn, to define vibroisolation properties of semi-active suspension systems.
PL
W pracy przedstawiono sposób projektowania systemu sterowania semi-aktywnym układem zawieszenia siedziska. Analizowano algorytm sterowania semi-aktywnego, który bazuje na modelu odwrotnym elementu sprężystego lub tłumiącego oraz na kontrolerze głównym. Procedura optymalizacji zaproponowana w pracy dodatkowo wspomaga dobór nastaw regulatora, ktore to nastawy definiują właściwości wibroizolacyjne semi-aktywnego układu zawieszenia.
13
Content available remote Concept of the Control System for a Single Wheelset With Independently Rotating Wheels Driven by Induction Motors
51%
Maciejewski I. , Krzyżyński T. , Chudzikiewicz A. , Sowińska M.
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tom Vol. 40, No. 1
53--63
EN
The aim of this contribution is to introduce the new concept for controlling a single wheelset with independently rotating wheels. The work concentrates on the drive control using a scalar control of three-phase induction motor. In the scalar control, the speed of particular wheels is controlled by the adjustable magnitude of voltage and frequency in such a way that constant ratio of the voltage to frequency is fulfilled. As results of the computer simulations, the dynamics of an exemplary railway wheelset is investigated.
14
Content available remote On Application of Fuzzy Logic in Active Control of Truck Driver's Seat
51%
Krzyżyński T. , Maciejewski I. , Chamera S.
Machine Dynamics Problems
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2004
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tom Vol. 28, No. 1
91-100
EN
The paper contains mathematical model of active control of truck driver seat suspension. Serial produced seat with a passive pneumatic suspension, that vibroisolation properties became improved by active control, is the object of simulation. Distributing element in this case is a flow proportional valve, receiving signal from fuzzy controller. Simulation has been carried out using of real excitations obtained during measurement of the truck floor vibrations. As results of computer simulations sample courses of acceleration and displacement for seat active suspension have been presented in comparison with those measured on the truck floor.
15
Content available remote On Steady State Dynamics of Railway Tracks Modelled as Continuous Periodic Structures
51%
Kruse H. , Popp K. , Krzyżyński T.
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tom Vol. 20
149-166
EN
This paper deals with an advanced linear model for the vertical track motion. Left and right rail and sleepers are modelled as Timoshenko beams. The pads and the ballast/ subsoil can have an arbitrary frequency dependent complex stiffness. Hence, an additional damping due to wave radiation in the subsoil can be considered. The steady state solution for the system under uniformly moving harmonic forces is derived by Fourier and Laplace transform techniques. Numerical calculations are performed with system parameters of a track commonly used in Germany. The influence of the non-continuous rail support and the system behaviour at critical pairs of load velocity and load frequency are investigated. Furthermore, the consequences of shear deformation of the rails and the effect of the sleeper elasticity on the system dynamics are examined.
16
Content available remote Semi-Active Vibration Control with Shunted Piezoceramics
51%
Oleśkiewicz R. , Neubauer M. , Krzyżyński T. , Popp K.
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tom Vol. 29, No. 4
109-125
EN
Piezoelectric materials because of their unique ability of converting mechanical energy into electrical energy and vice versa can be found in numerous mechanical vibration damping applications. Connecting a suitable shunt branch to the piezoelectric actuator results in an electromechanical vibration damping or absorbing system, depending on the complex impedance describing the external network. A limited performance of the pure passive techniques involving resistive and inductive elements depending only on the electromechanical coupling coefficient can be significantly increased by the use of the negative capacitance element. Such an approach requires external power supply because of the necessary impedance converter built up of the operational amplifiers. The paper presents the recent research on the negative capacitance application in semi passive vibration control systems with piezoceramics, where the different configurations of external RLC-networks are analyzed. The electromechanical system consists of one degree of freedom spring mass damper oscillator with a piezoelectric actuator placed between the mass and the base. The analysis is performed in a general, normalized form, highlighting the influence of the negative capacitance and the general electromechanical coupling coefficient of the piezoceramics. The optimal parameters of the shunt branch resulting in maximal damping and absorbing performance of the system are given in an analytical form. The analytical results have been experimentally verified using a test rig.
17
Content available remote On influence of pad features on dynamics of a railway track
51%
Bogacz R. , Kamiński A. , Krzyżyński T.
Engineering Transactions
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2000
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tom Vol. 48, iss. 3
329-340
EN
The vertical track dynamic model is described in the paper as a periodic structure. It is composed of rails modelled as Timoshenko or Bernoulli-Euler beams, sleepers (lumped masses) and pads and ballast modelled as viscoelastic elements. Particular attention is paid to the influence of pad characteristics on the dynamic stiffness of the track. One of the ideas of the new pad generation is also presented in the paper. Some parameters of the pad are given.
18
Content available remote Applications of Fuzzy Logic Methods to Disturbances Compensation in Processes of Fine Grinding
51%
Kacalak W. , Lipiński D. , Krzyżyński T.
Machine Dynamics Problems
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2002
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tom Vol. 26, No. 4
93-100
EN
In the paper, a fuzzy system of compensation of position deviation of a grinding wheel in relation to a grinded work-piece is presented. An analytical solution of the problem of disturbances compensation requires a full description of the system properties. Greater problem complexity occurs in cases of an integration of grinding processes and smoothing of abrasive-resistant materials with auxiliary processes, as well as in cases of an automated grinding by means of many grinding wheels of different characteristics. It is advisable then to determine fuzzy relations and to work out a system of fuzzy compensation. Proposed algorithm of fuzzy compensation method considerably corrects a quality and stability of the fine grinding process.
19
Content available remote Research and development of seat suspensions for working machines
51%
Maciejewski I. , Kiczkowiak T. , Krzyżyński T.
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2009
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tom Vol. 19, no. 4
463-478
EN
The paper contains physical and mathematical model of passive and active control of working machine's seat suspension. Seat with a viscous-elastic passive suspension, which vibro-isolation properties became improved by modification of the air-spring and shock absorber forces and also by active control are the objects of simulation. As the results of computer simulation, power spectral density of acceleration for a seat have been presented in comparison with sample excitation on the working machine's cabin floor. Transmissibility functions for a passive suspension and corresponding active suspension also have been presented.
20
Content available Aktywny układ zawieszenia siedziska z siłownikiem pneumatycznym stosowany do ochrony operatorów maszyn roboczych przed drganiami w poziomym kierunku oddziaływania
51%
Markiewicz W. , Maciejewski I. , Krzyżyński T.
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tom R. 23, nr 12
145--150
PL
W artykule został przedstawiony fizyczny oraz matematyczny model aktywnego układu redukcji drgań z siłownikiem pneumatycznym, który może być zastosowany w układzie zawieszenia siedziska operatora maszyny roboczej. Na podstawie badań symulacyjnych i doświadczalnych wykazano małą skuteczność redukcji drgań mechanicznych pasywnego układu zawieszenia siedziska w zakresie częstotliwości 0,5 – 10 Hz dla poziomego kierunku oddziaływania drgań, zgodnego z kierunkiem ruchu maszyny roboczej. Opracowany został model aktywnego układu redukcji drgań z zastosowaniem siłownika pneumatycznego, którego skuteczność wyznaczono na podstawie badań symulacyjnych. Jako rezultaty symulacji komputerowej przedstawiono gęstości widmowe mocy przyspieszenia drgań i funkcje przenoszenia.
EN
The paper deals with physical and mathematical models of the active vibration reduction system with pneumatic actuator used for the horizontal seat suspension. In the basis of the numerical simulation, that is conducted for the excitation signal having the properties of white noise in the frequency range of 0.5 - 10 Hz, the low effectiveness of horizontal passive vibration reduction systems is shown in comparison with the active one. Appropriate selection of the model allows to obtain simulation results close to the dynamic behavior of a real system. The power spectral density of vibration acceleration and the transmissibility functions are presented as the results of computer simulations using the Matlab-Simulink software package. Analysis of the results leads to the conclusion concerning the hydraulic actuator effectiveness in application to vibration reduction systems.
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