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Wyniki wyszukiwania dla: radio frequency disturbances
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Spectral Finite Element Method in Condition Monitoring and Damage Detection
PublikacjaIt is well known that the dynamic behaviour of engineering structures may carry very important and crucial information that can be further used for the assessment of their condition as well as detection of any damage induced. The current interest in monitoring techniques based on the propagation of guided elastic waves requires that numerical techniques used for modelling the phenomena associated must shift into the realm of high...
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WARUNKI REZONANSOWE W WĘŹLE Z KOMPENSATOREM SVC
PublikacjaInstalowanie kompensatorów statycznych w sieciach rozdzielczych i przesyłowych służy poprawie profili napięciowych. Kompensatory jako źródła mocy biernej zwiększają stabilność napięciową systemu. Pozwalają także na szybszą odbudowę systemu w przypadku awarii napięciowej. W artykule zaprezentowano wpływ struktury i wysterowania układu SVC na zmianę impedancji w układzie zasilania. Ma to bezpośredni wpływ na częstotliwości, przy...
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Planar Microwave Bragg Reflector Resonant Dielectric Sensor
PublikacjaIn this paper, a periodic structure is used to design a microwave Bragg reflector with the help of hexagonal lattice, which provides a 5 GHz wide stopband between the low-pass band with cut-off frequency 2.6 GHz and the bandpass response with start and stop frequency 7.8 GHz and 10.5 GHz, respectively. A defect in lattice allows passing a narrowband signal at 6 GHz which is found, from the dispersion relation, to be in the region...
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Smart acoustic band structures
PublikacjaSmart acoustic band structures exhibit very interesting and non-standard physical properties due to the periodic nature of their certain characteristic on different scale levels. They manifest mostly in their frequency spectra as socalled frequency band-gaps or stop-bands, what has a great impact on the behaviour of these structures in relation to the propagation of vibro-acoustic signals that can be transmitted through the structures...
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Design of Microwave-Based Angular Displacement Sensor
PublikacjaThis letter presents a novel microwave-based rotation sensor having a wide dynamic range to detect and measure the angular displacement in terms of the change in resonant frequency. The proposed sensor is based on the microstrip technology, where a rotor comprised of a complementary splitring resonator (CSRR) placed on the ground plane of the microstrip line is free to rotate around its axis. The mechanical rotation of CSRR determines...
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A concept of Signal Equalization Method Based on Music Genre and the Listener's Room Characteristics
PublikacjaA research study that investigates the influence of the room acoustics environment on the frequency characteristic of the audio signal playback is presented. First, a novel spectral equalization method of the room acoustic conditions is introduced. On the basis of the frequency response of the room, a system for room acoustics compensation based on eight-band equalizer is proposed. The system settings depend on music genre. In...
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Continuous blood pressure monitoring by photoplethysmography - signal preprocessing requirements based on blood flow modelling
PublikacjaObjective. The aim of the study is to investigate the effect of the signal sampling frequency and low-pass filtering on the accuracy of the localisation of the fiducial points of the photoplethysmographic signal (PPG), and thus on the estimation of the blood pressure (i.e. the accuracy of the estimation). Approach. Statistical analysis was performed on 3,799 data samples taken from a publicly available database. Four PPGfiducial...
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Implementacja w technologii radia programowalnego transceivera opartego na technice OFDM pracującego w trybie dupleksu czasowego
PublikacjaTechnika OFDM jest obecnie jedną z najbardziej popularnych metod realizacji szybkiej transmisji danych w warstwie fizycznej współczesnego systemu radiokomunikacyjnego. Choć jej wykorzystanie w technologii radia programowalnego w celu realizacji jednokierunkowej transmisji jest dość powszechne, to wciąż trudno znaleźć przykłady implementacji łączy dwukierunkowych czasu rzeczywistego, w szczególności tych opartych na trybie dupleksu...
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Voltage Harmonics Transfer through Medium Voltage Instrument Transformers
PublikacjaVoltage transformers are widely used in power quality monitoring systems in medium and high voltage grids. This paper presents accuracy problems related to voltage harmonics transfer through instrument transformers. A simplified lumped-parameters wideband circuit model of the voltage transformer is proposed and verified by simulation and experimental investigations. A number of voltage transformers have been tested in the frequency...
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Music signal equalization in a changing environment
PublikacjaThe paper presents the concept of an automatic system for music signal correction, considering room frequency response and music genre being played. The proposed algorithm, based on the room frequency response, compensates acoustic conditions surrounding the sound source. Additionally, the compensation process considers the signal content by recognizing music genre. As part of the described research, a series of subjective tests...
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New Algorithms for Adaptive Notch Smoothing
PublikacjaThe problem of extraction/elimination of a nonstationary complex sinusoidal signal buried in noise is considered. This problem is usually solved using adaptive notch filtering (ANF)algorithms. It is shown that accuracy of signal estimation can be increased if the results obtained from ANF are further processed using a cascade of appropriately designed filters. The resulting adaptive notch smoothing (ANS) algorithms can be employed...
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Simplified Method of Modelling Behaviour of Ship in Waves with Partially Flooded Compartments
PublikacjaThis paper contains a description of a numerical model for calculating behaviour of ships in waves. There are many models available, but the one described here can be characterised with a set of parameters that have a decisive impact on the final values of roll motion amplitude and frequency. In this paper, it is shown how a fitting of a standard-shape hull characterised by certain readily available parameters affects...
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A concept of software extension of 3D low-PRF radar systems to 4D semi-medium-PRF radar systems
PublikacjaWe present a concept of software modification of three-dimensional (3D) radar systems, designed to work in the low pulse repetition frequency mode, that equips them with the ability to estimate the radial velocity and to properly measure the range of targets that are detected outside the radar’s instrumented range. Despite the fact that the proposed modifications are designed so as to require only minor changes in software, they...
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Stress Detection of Children With ASD Using Physiological Signals
PublikacjaThis paper proposes a physiological signal-based stress detection approach for children with autism spectrum disorder (ASD) to be used in social and assistive robot inter- vention. Electrodermal activity (EDA) and blood volume pulse (BVP) signals are collected with an E4 smart wristband from children with ASD in different countries. The peak count and signal amplitude features are derived from EDA signal and used in order to detect...
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Comparison of state feedback and PID control of pressurizer water level in nuclear power plant
PublikacjaThe pressurizer water level control system in nuclear power plant with pressurized water reactor (PWR) is responsible for coolant mass balance. The main control goal is to stabilize the water level at a reference value and to suppress the effect of time-varying disturbances (e.g. coolant leakage in primary circuit pipeline system). In the process of PWR power plant operation incorrect water level may disturb pressure control or...
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SLIDING MODE-PID FUZZY CONTROLLER WITH A NEW REACHING MODE FOR UNDERWATER ROBOTIC MANIPULATORS
PublikacjaDesign of an accurate and robust controller is a challenging topic in an underwater manipulator control. This is due to hydrodynamic disturbances in underwater environment. In this paper a sliding mode control (SMC) included a PID sliding surface and fuzzy tunable gain is designed. In this proposed controller robustness property of SMC and fast response of PID are incorporated with fuzzy rules to reduce error tracking. In the...
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TIME-AND-SPACE STRUCTURE OF FORCE-DRIVEN RIGID SPHEREWAVEFIELD
PublikacjaThis paper introduces a time-domain, causality-inspired description of a vector-source acoustic wavefield of arbitrary time evolution, where a sphere is a practical realisation of quasi-point contact surface without which a point force would not be able to exert an impact onto non-viscous fluid. At every space location, the resulting acoustic field is described by a pair of physical variables characterising the time evolution of...
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Treatment of landfill leachate in a constructed free water surface wetland system over a decade – Identification of disturbance in process behaviour and removal of eutrophying substances and organic material
PublikacjaAn 8 ha free water surface wetland system in Örebro, Sweden, which has sediment traps followed by 10 ponds for treatment of landfill leachate in the methanogenic stage, was studied from 2003 to 2012. The wetland was irregularly loaded and the leachate characteristics showed high temporal and spatial variability, so Multivariate Statistical Process Control was chosen as the diagnostic tool for detecting anomalies prior to assessing...
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Topological Model of an Electromagnetic Environment Inside a Ship for Electromagnetic Compatibility (EMC) Analysis
PublikacjaThe mutual electromagnetic (EM) interactions between electrical and electronic devices in a segmented space, such as a ship's environment, ared described. Firstly, the topological structure of a ship's segmented internal environment, which consists of many electrical screening walls (shielding planes), is presented. Then, taking into account the ship's topological structure, a general description of the EM disturbance distribution,...
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Two-Level Multivariable Control System of Dissolved Oxygen Tracking and Aeration System for Activated Sludge Processes
PublikacjaThe problem of tracking dissolved oxygen is one of the most complex and fundamental issues related to biological processes. The dissolved oxygen level in aerobic tanks has significant influence on behaviour and activity of microorganism inhabiting the plant. Aerated tanks are supplied with air from an aeration system (blowers, pipes, throttling valves, diffusers). It is a complex dynamic system governed by nonlinear hybrid dynamics....
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Merging extremum seeking and self-optimizing narrowband interference canceller - overdetermined case
PublikacjaActive cancellation systems rely on destructive interference to achieve rejection of unwanted disturbances entering the system of interest. Typical practical applications of this method employ a simple single input, single output arrangement. However, when a spatial wavefield (e.g. acoustic noise or vibration) needs to be controlled, multichannel active cancellation systems arise naturally. Among these, the so-called overdetermined...
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Asynchronous WAM with Irregular Pulse Repetition
PublikacjaRadiolocation systems for aviation based on Multi-Lateration (MLAT) typically use a set of synchronised ground sensors to receive radio signals broadcast by onboard transmitters. In most cases, the sensor synchronisation in Wide Area Multi-Lateration Systems (WAM) is provided by Global Navigation Satellite System (GNSS) receivers. However, in the case of synchronisation failure, there is still a possibility to estimate the coordinates...
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Application of OFDM technique to underwater acoustic data transmission
PublikacjaPerformances of underwater acoustic communication (UAC) digital systems are strongly related to specific transmission properties of the underwater channel. Depending on the characteristics of the channel, an architecture and modulation techniques are usually implemented that are known as reliable solutions for data transmission in difficult radio channels. The OFDM technique seems to be the most promising nowadays. The parameters...
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Underwater Acoustic Communications in Time-Varying Dispersive Channels
PublikacjaUnderwater acoustic communication (UAC) system designers tend to transmit as much information as possible, per unit of time, at as low as possible error rate. However, the bit rate achieved in UAC systems is much lower than for wire or radio-communication systems. This is due to disadvantageous properties of the UAC channels, namely the sea and inland waters. Estimation of UAC channel transmission properties is possible within...
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Capillary pumped loop as a tool for collecting large heat fluxes from electronic devices on warships
PublikacjaThe combat potential of future warships will be directly related to the use of modern electronic devices being parts of advanced systems, such as, for instance, radar systems, fire aiming systems, fire detection systems, electric drive systems, and even electronic and radio-electronic weaponry, railguns and lasers, installed on these warships. The capacity and functionality of these devices is continually increasing, at decreasing...
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VUV photofragmentation of the six-membered heterocyclic molecules containing oxygen
PublikacjaCancer is a significant public health concern worldwide, which results in millions of deaths each year. The standard cure routine for cancer is surgery, and nowadays, radiotherapy or a hadrontherapy. Depending on the type of cancer, patients may undergo additional treatment, including targeted therapy. A combination of radio- or hadron-therapy with proper drug treatment can inhibit the proliferation of cancer cells and thus can...
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System Loss Model for Body Area Networks in Room Scenarios
PublikacjaThis paper presents an analysis of system loss in Body Area Networks for room scenarios, based on a wideband measurement campaign at 5.8 GHz. The measurements were performed with a fixed antenna transmitting vertically and horizontally polarised signals, while the user wears dualpolarised antennas. The average system losses in co- and crosspolarised channels are 41.4 and 42.6 dB for vertically polarised transmitted signals and...
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Fast geometry scaling of miniaturized microwave couplers with power split correction
PublikacjaRedesigning a microwave circuit for various operating conditions is a practically important yet challenging problem. The purpose of this article is development and presentation of a technique for fast geometry scaling of miniaturized microwave couplers with respect to operating frequency. Our approach exploits an inverse surrogate model constructed using several reference designs that are optimized for a set of operating frequencies...
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Nonlinear electrical properties of glass-ceramics nanocomposites containing ferroelectric nanocrystallites of Bi2VO5.5
PublikacjaNonlinear A.C. impedance measurements were conducted in the 50BiV-50SrBAlO nanocomposite as a function of frequency, temperature and A.C. voltage. This material is ferroelectric below temperature of 730 K, and above 730 K is a good ion-conductor. For this nanocomposite a low A.C. voltage of 1 V rms is enough to observe high nonlinearities. The origin of these nonlinear effects depends on the temperature and frequency. In the high...
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A Geometrically Simple Compact Wideband Circularly Polarized Antenna
PublikacjaA compact broadband wide-slot circular polarization (CP) antenna is proposed. An inverted L-shape parasitic strip at the open end of a microstrip line extension and a slot modification is applied to attain wideband CP. The advantage of this technique is simplicity which makes it readily re-designable for different frequency bands. To demonstrate the concept, three designs working at different frequencies are obtained. The redesign...
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Independent dynamics of slow, intermediate, and fast intracranial EEG spectral activities during human memory formation
PublikacjaA wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various low and high frequencies are spatiotemporally coordinated across the human brain during memory processing is inconclusive. They can either be coordinated together across a wide range of the frequency spectrum or induced in specific bands. We used a large dataset of human intracranial electroencephalography...
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An Efficient PEEC-Based Method for Full-Wave Analysis of Microstrip Structures
PublikacjaThis article introduces an efficient method for the equivalent circuit characterization and full-wave analysis of microstrip structures, leveraging the full-wave partial element equivalent circuit (PEEC). In particular, the multilayered Green's function is evaluated using the discrete complex-image method (DCIM) and employed to establish the mixed potential integral equations. The proposed strategy considers time delays for the...
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Expedited simulation-driven design optimization of UWB antennas by means of response features
PublikacjaIn this work, a method for fast design optimization of broadband antennas is considered. The approach is based on a feature-based optimization (FBO) concept where reflection characteristics of the structure at hand are formulated in terms of suitably defined feature points. Redefinition of the design problem allows for reducing the design optimization cost, because the dependence of feature point coordinates on antenna dimensions...
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Behavior of residual current devices at frequencies up to 50 kHz
PublikacjaThe use of residual current devices (RCDs) is obligatory in many types of low-voltage circuits. They are devices that ensure protection against electric shock in the case of indirect contact and may ensure additional protection in the case of direct contact. For the latter purpose of protection, only RCDs of a rated residual operating current not exceeding 30 mA are suitable. Unfortunately, modem current-using equipment supplied...
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Miniaturized uniplanar triple-band slot dipole antenna with folded radiator
PublikacjaA miniaturized uniplanar slot dipole for triple-frequency operation is presented. The antenna consists of a folded slot radiator with an increased number of degrees of freedom that allow for efficient size reduction. Rigorous electromagnetic (EM)-driven design optimization is applied in order to achieve the smallest possible size while maintaining acceptable levels of antenna reflection at the required operating frequencies. The...
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Nonlinear Impedance as Possible Result of Ion-Polaron Interaction in Cu2O-Al2O3-SiO2 Glass
PublikacjaNonlinear a.c. impedance measurements were performed in Cu2O-Al2O3-SiO2 glass in wide frequency range. The obtained results shows that a large nonlinearity in the impedance signal is observed at moderate electric fields of an order 1V/mm. The contents of the third harmonics reaches about 10% and strongly depends on temperature and frequency. The investigated glass exhibits mixed electronic-ionic conductivity. Electronic conduction...
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An Analysis of Elliptical-Rectangular Multipatch Structure on Dielectric-Coated Confocal and Nonconfocal Elliptic Cylinders
PublikacjaA rigorous analysis of the resonance frequency problem of an elliptical-rectangular microstrip structure mounted on dielectric-coated elliptic conducting cylinder, with electrically small radius, is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. The analysis is carried out considering the expansion of the field as a series of Mathieu functions. The complex resonance frequencies of...
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Simulation of Signal Propagation Along Fractional-Order Transmission Lines
PublikacjaIn this paper, the simulation method of signal propagation along fractional-order (FO) transmission lines is presented. Initially, fractional calculus and the model of FO transmission line are introduced. Then, the algorithm allowing for simulation of the nonmonochromatic wave propagation along FO transmission lines is presented. It employs computations in the frequency domain, i.e., an analytical excitation is transformed to the...
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Uniwersalny Kontroler Radiowy w systemie STRADAR
PublikacjaOpisano praktyczne rozwiązanie uniwersalnego kontrolera radiowego UKR – jednego z podstawowych elementów funkcjonalnych systemu STRADAR – który obsługuje sensory wykorzystywane na granicy morskiej państwa. Jest on także odpowiedzialny za komunikację personelu Straży Granicznej. UKR ma dwie wersje, jedną mobilną – na jednostki pływające, pojazdy lądowe i jednostki latające, drugą stacjonarną – na stałe punkty obserwacyjne rozmieszczone...
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Sound signals generated during lapping of technical ceramics using electroplated tools with diamond grains
Dane BadawczeData contains the recordings of sound generated during single-sided lapping with the use of electroplated diamond tools. This relationship was examined with the use of spectral analysis of the sound signal in the frequency domain with a focus on the Ra parameter of the surface roughness. The estimated sound coefficient increased as the surface roughness...
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TRANSFER OF ELECTRIC ENERGY [2023/24]
Kursy OnlineCourse content: Basic information on the structure of the power system, the major devices (components) for generation, transmission and distribution of electricity. Active and reactive power generation and their sources. Power supply networks. Tasks, structure, parameters. AC and DC transmission of electricity. Equivalent diagrams of the components of the power system. Steady state load flow calculation: currents, voltage,...
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TRANSFER OF ELECTRIC ENERGY [2022/23]
Kursy OnlineCourse content: Basic information on the structure of the power system, the major devices (components) for generation, transmission and distribution of electricity. Active and reactive power generation and their sources. Power supply networks. Tasks, structure, parameters. AC and DC transmission of electricity. Equivalent diagrams of the components of the power system. Steady state load flow calculation: currents, voltage,...
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TRANSFER OF ELECTRIC ENERGY [2024/25]
Kursy OnlineCourse content: Basic information on the structure of the power system, the major devices (components) for generation, transmission and distribution of electricity. Active and reactive power generation and their sources. Power supply networks. Tasks, structure, parameters. AC and DC transmission of electricity. Equivalent diagrams of the components of the power system. Steady state load flow calculation: currents, voltage, power,...
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TRANSFER OF ELECTRIC ENERGY [2024/25]
Kursy OnlineCourse content: Basic information on the structure of the power system, the major devices (components) for generation, transmission and distribution of electricity. Active and reactive power generation and their sources. Power supply networks. Tasks, structure, parameters. AC and DC transmission of electricity. Equivalent diagrams of the components of the power system. Steady state load flow calculation: currents, voltage,...
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Analysis of noise properties of the optocoupler device
PublikacjaIn the paper the localization of a source of Random Telegraph Signal noise (RTS noise) in optocoupler devices type CNY 17 were defined. The equivalent noise circuit in low frequency noise for these type optocouplers was proposed.
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Zastosowanie metody galwanostatycznej do wyznaczania błędu fazy elektrod woltamperometrycznych
PublikacjaW pracy przeanalizowano właściwości metrologiczne elektrod woltamperometrycznych w dziedzinie częstotliwości. Wykazano, że w przypadku, gdy reakcja elektrochemiczna kontrolowana jest procesem transportu jonów, elektroda woltamperometryczna zachowuje się tak jak przetwornik pomiarowy I rzędu. Jej właściwości metrologiczne opisane są przez czułość, częstotliwość graniczną, błąd amplitudy i błąd fazy. Przeprowadzona analiza pokazała,...
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Dynamika bezzałogowego aparatu latającego w układzie czterowirnikowego pionowzlotu
PublikacjaDziałanie maszyn, w tym również pojazdów latających, jest nieodłącznie związane z przekazywaniem oddziaływań siłowych: statycznych i dynamicznych. Dynamika jest działem mechaniki zajmującym się makroskopowym ruchem ciał przy uwzględnieniu przyczyn wywołujących ten ruch. Pierwszym etapem analizy dynamiki konstrukcji są zwykle obliczenia wartości i postaci drgań własnych modelu konstrukcji. Drgania własne zwykle ulegają szybkiemu...
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FIR Filter Design Using Distributed Maximal Flatness Method
PublikacjaIn the paper a novel method for filter design based on the distributed maximal flatness method is presented. The proposed approach is based on the method used to design the most common FIR fractional delay filter - the maximally flat filter. The MF filter demonstrates excellent performance but only in a relatively narrow frequency range around zero frequency but its magnitude response is no greater than one. This ,,passiveness”...
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Corrosion process monitoring by AFM higher harmonic imaging
PublikacjaThe atomic force microscope (AFM) was invented in 1986 as an alternative to the scanning tunnelling microscope, which cannot be used in studies of non-conductive materials. Today the AFM is a powerful, versatile and fundamental tool for visualizing and studying the morphology of material surfaces. Moreover, additional information for some materials can be recovered by analysing the AFM's higher cantilever modes when the cantilever...
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Modeling sequencing batch reactor operational conditions depending on oxygen concentration
PublikacjaSequencing batch reactors (SBR) can be used as a fill-and draw activated sludge system for wastewater treatment with considerable operating flexibility and the possibility to conduct experiments under standard conditions and extreme case scenarios. Mathematical modeling and computer simulations provide an opportunity to implement existing wastewater processes in modeling software and evaluate different modifications at low costs...