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Search results for: HIGH FREQUENCY DYNAMICS
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OCENA UZIEMIEŃ SŁUPÓW LINII ELEKTROENERGETYCZNYCH ZWŁASZCZA POSADOWIONYCH NA GRUNTACH O WYSOKIEJ REZYSTYWNOŚCI
PublicationW artykule została omówiona problematyka pomiaru i oceny właściwości uziemień słupów linii elektroenergetycznych z wykorzystaniem przebiegów wolno-i szybkozmiennych. Uzyskanie odpowiednio niskiej wartości rezystancji uziemienia słupa posadowionego na gruncie o rezystywności powyżej 1000Ωm może być trudne. Praca zawiera analizę zmian właściwości statycznych i udarowych uziemień w funkcji rezystywności...
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Spectral analysis of nonstationary low-frequency magnetic-field emissions from ship's power
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Parametry uziemień przy przebiegach udarowych i wysokoczęstotliwościowych
PublicationW artykule skupiono się na porównaniu dwóch metod badania impedancji uziemienia odgromowego: udarowej z wysoką częstotliwościową. Zestawiono wyniki pomiarów istniejących uziemień z wynikami komputerowych obliczeń symulacyjnych przeprowadzonych w środowisku programu PSIM. Uzyskane wyniki wskazują na poprawność przyjętego toku modelowania, a uzyskane w ten sposób dane mogą być przydatne w fazie projektowania do szacowania...
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Pompownie dużej mocy z falownikiem wędrującym średniego napięcia
PublicationArtykuł zawiera rys rozwoju napędów przekształtnikowych w stacjach pomp, w szczególności regulacji wydatku kilku pomp, po kolei, przez jeden przemiennik częstotliwości. Omówiono podstawy teoretyczne zjawiska pola niestłumionego i napięcia resztkowego silników, które utrudniają szybkie przełączania silnika pompy pomiędzy zasilaniem regulowanym przez falownik a zasilaniem z sieci. Przedstawiono zasady transferu (przełączania) synchronicznego...
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WARUNKI REZONANSOWE W WĘŹLE Z KOMPENSATOREM SVC
PublicationInstalowanie 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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Analiza drgań przewodu jezdnego sieci trakcyjnej w aspekcie oceny jej stanu technicznego.
PublicationGórna sieć trakcyjna jest nadal najefektywniejszym sposobem zasilania kolejowych pojazdów elektrycznych. Sieć jezdna nie ma możliwości technicznych redundancji, co wymaga okresowej oceny stanu technicznego w celu zapewnienia prawidłowej współpracy z odbierakami prądu pojazdów. W artykule przedstawiono aspekty oceny stanu technicznego górnej sieci trakcyjnej na podstawie modelowania matematycznego i wybranych badań laboratoryjnych....
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Effect of power frequency on the stress state of disc actuator
PublicationThe paper presents the concept of determinig the optimum frequency of coil supply in inductive-dynamic drive. As a criterion to obtain the sought frequency, the smallest value of reduced stress in the disc was assumed while maintaining the desired dynamics.
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On the instantaneous frequency smoothing for signals with quasi-linear frequency changes
PublicationThe problem of estimation of the slowly-varying instantaneous frequency of a nonstationary complex sinusoidal signal buried in noise is considered. This problem is usually solved using frequency tracking algorithms. It is shown that the accuracy of frequency estimates can be considerably increased if the results yielded by the frequency tracker are further processed using the appropriately designed filters. The resulting frequency...
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Frequency measurement research with weight averaging of pulse output signal of voltage-to-frequency converter
PublicationThe paper presents the essence and investigation of the efficiency of weight averaging of a pulse output signal of voltage-to-frequency converter. The effect of counting and the influence of interference on the result of weight averaging of frequency modulated pulses are analyzed. It is shown that from the point of view of counting error reduction, the best are polynomial weight functions. In the case of high interferences whose...
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Analiza wielokryterialna wariantów systemu zaopatrzenia w wodę zespołu padów
PublicationJednym z istotnych problemów decyzyjnych na etapie potencjalnej eksploatacji gazu z formacji łupkowych jest wybór sposobu zaopatrzenia w wodę kopalni gazu łupkowego. Z uwagi na duże zapotrzebowanie na wodę do procesu szczelinowania kolejno przekazywanych do eksploatacji odwiertów wydobywczych, należy poszukiwać systemu zaopatrzenia w wodę, który zagwarantuje wymaganą jej ilość, a jednocześnie nie będzie zbyt dużym obciążeniem dla...
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From the multiple frequency tracker to the multiple frequency smoother
PublicationThe problem of extraction/elimination of nonstationary sinusoidalsignals from noisy measurements is considered. This problem is usually solved using adaptive notch filtering (ANF)algorithms. It is shown that the accuracy of frequency estimates can be significantly increased if the results obtained from ANF are backward-time filtered by an appropriately designed lowpass filter. The resulting adaptive notch smoothing (ANS)algorithm...
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Effect of power frequency on the stress state of disc actuator
PublicationThis paper presents the concept of determining the optimum frequency of coil supply in inductive-dynamic drive. As a criterion to obtain the sought frequency, the smallest value of reduced stress in the disc was assumed while maintaining the desired dynamics. The disc stress is determined on the basis of solution of vibrating thin plate equation. Magnetic pressure acting on the disc is obtained from a hybrid circumferentially-field...
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Problems with microprocessor voltage-to-frequency and frequency-to-voltage converters implementation
PublicationThe article presents the problems of digital voltage-to-frequency and frequency-to-voltage processing. Transducer systems implemented in microprocessor technology are presented, the timing of signals and functioning algorithms are discussed. An analysis of processing errors has been performed and the results of experimental studies of realized systems are presented.
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The influence of frequency separation on imaging properties in DFEIT
PublicationW artykule przedstawiono wpływ wyboru składowych częstotliwościowych dla różnicowej tomografii impedancyjnej na wynik i własności obrazowania w dwuczęstotliwościowej różnicowej tomografii impedancyjnej.A Dual Frequency EIT is an extension of a traditional EIT that uses two sinusoidal signals for imaging. Appropriate selection of signals' frequency allows to achieve reasonable contrast of imaged structure. It has already been shown...
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Jednofazowy falownik napięcia z aktywnym obwodem odsprzęgającym
PublicationZnanym zagadnieniem w jednofazowych falownikach napięcia jest pobieranie ze źródła napięcia stałego składowej przemiennej o częstotliwości dwukrotnie większej od częstotliwości generowanej przez falownik. Jednym z rozwiązań problemu jest stosowanie dużej baterii kondensatorów elektrolitycznych, lecz lepszym sposobem z punktu widzenia niezawodności i gęstości mocy przekształtnika jest stosowanie aktywnych układów odsprzęgania mocy....
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Metody usuwania zakłóceń podczas pomiarów polowych widm Ramana
PublicationW pracy zostały scharakteryzowane źródła zakłóceń występujące podczas pomiarów widm Ramana w warunkach polowych. Zaprezentowano wpływ czasu integracji na jakość rejestrowanych widm w przypadkach, gdy szumy własne spektrometru mają składową typu 1/f, dominującą w zakresie małych częstotliwości. Przedstawiono także wyniki uzyskane podczas pomiarów z detekcją synchroniczną, stosowaną w przenośnych spektrometrach Ramana, w pomiarach...
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Frequency Diagnostics of Transformer Insulating Parameters
PublicationIn the article is presented experimental analysis and diagnostics of insulating system oil-paper for power transformers, mainly by progressive frequency method – dielectric spectroscopy. In the 1-st part of the article is described base theory about measurement and diagnostics insulating part (oil and paper) of power transformers. In the 2-nd part of article is described measuring method of insulating frequency diagnostics - frequency...
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Dynamics of quantum entanglement
PublicationA model of discrete dynamics of entanglement of a bipartite quantum state is considered. It involves a global unitary dynamics of the system and periodic actions of local bistochastic or decaying channel. For initially pure states the decay of entanglement is accompanied by an increase of von Neumann entropy of the system. We observe and discuss revivals of entanglement due to unitary interaction of subsystems. For some mixed states...
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Directed pulse dynamics
PublicationIntroducing a projection method into a one-dimensional model of a pulse propagation in isotropic media, we derive and investigate a system of equation describing dynamics ultrashort pulses of opposite directions ofpropagation and ones with interaction of directed pulses with different polarization.
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Towards detecting programmers’ stress on the basis of keystroke dynamics
PublicationThe article describes the idea of detecting stress among programmers on the basis of keystroke dynamics. An experiment with a group of students of artificial intelligence classes was performed. Two samples of keystroke data were recorded for each case, the first while programming without stress, the second under time pressure. A number of timing and frequency parameters were calculated for each sample. Then statistical analysis...
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Fast bubble dynamics and sizing
PublicationSingle bubble sizing is usually performed by measuring the resonant bubble response using the Dual Frequency Ultrasound Method. However, in practice, the use of millisecond-duration chirp-like waves yields nonlinear distortions of the bubble oscillations. In comparison with the resonant curve obtained under harmonic excitation, it was observed that the bubble dynamic response shifted by up to 20 percent of the resonant frequency...
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Implementation of an Adaptive Method for Changing the Frequency Division of the Counter Clock Signal in a Frequency-to-Code Converter
PublicationProcessing physical quantities into an indirect signal is a standard method of transferring information about the measured quantity to the master system, which analyzes the data obtained from the acquisition system. The intermediate signal is very often the voltage, but another transmission medium can be the frequency of the output signal of the “physical quantity-to-frequency” converter. The article presents the implementation...
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Synteza układu sterowania statkiem morskim dynamicznie pozycjonowanym w warunkach niepewności
PublicationNiniejsza monografia obejmuje zagadnienia związane z syntezą układu dynamicznego pozycjonowania statku w środowisku morskim z zastosowaniem wybranych nieliniowych metod sterowania. W ramach pracy autorka rozważała struktury sterowania z zastosowaniem wektorowej adaptacyjnej metody backstep oraz metod jej pokrewnych, takich jak regulatory MSS (ang. multiple surface sliding), DSC (ang. dynamic surface control), NB (ang. neural backstepping)....
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Dissecting gamma frequency activities during human memory processing
PublicationGamma frequency activity (30-150 Hz) is induced in cognitive tasks and is thought to reflect underlying neural processes. Gamma frequency activity can be recorded directly from the human brain using intracranial electrodes implanted in patients undergoing treatment for drug-resistant epilepsy. Previous studies have independently explored narrowband oscillations in the local field potential and broadband power increases. It is not...
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Przegląd systemów ładowania elektrycznych osobowych pojazdów i koncepcja dwukierunkowej ładowarki pokładowej
PublicationAktualnie trwa intensywny rozwój pojazdów elektrycznych (EV) i hybrydowych typu plug-in (PHEV) z pokładowymi bateriami akumulatorów. Badania w tej dziedzinie skupiają się na maksymalizowaniu sprawności oraz minimalizowaniu masy i objętości systemów ładowania baterii. W artykule przedstawiono podział systemów ładowania osobowych pojazdów typu EV/PHEV. Opisano systemy ładowania przewodowego z podziałem na ładowarki pokładowe i zewnętrzne, systemy...
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The instantaneous frequency rate spectogram
PublicationAn accelerogram of the instantaneous phase of signal components referred to as an instantaneous frequency rate spectrogram (IFRS) is presented as a joint time-frequency distribution. The distribution is directly obtained by processing the short-time Fourier transform (STFT) locally. A novel approach to amplitude demodulation based upon the reassignment method is introduced as a useful by-product. Additionally, an estimator of energy...
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Multiple-channel frequency-adaptive active vibration control using SONIC
PublicationSONIC (self-optimizing narrowband interference canceller) is an acronym of a new approach to rejection of sinusoidal disturbances acting at the output of a discretetime stable linear plant with unknown and possibly timevarying dynamics. The paper presents two frequency-adaptive extensions of the multivariate SONIC algorithm. The efficacy of the proposed solutions is tested using our laboratory-scale active vibration control plant.
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Dissociative ionization dynamics of dielectric gas C3F7CN
PublicationFluoronitrile C3F7CN is a promising candidate for the replacement of SF6 dielectric gas in high-voltage insulation. We present a combined experimental and theoretical study on its ionization dynamics probed in the 0-100 eV energy range. We exploited the total ion collection technique to determine the absolute ionization cross section, mass spectrometry to determine the fragment branching ratios and ab initio nonadiabatic molecular...
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Technological capability dynamics through cluster organizations
PublicationPurpose – The purpose of the paper is to portrait how members of cluster organizations (COs) perceive the role of COs in enabling them to accumulate technological capability (TC) significant for their innovation. Design/methodology/approach – The authors report the findings from their qualitative study based on an analysis of four COs. The organizational inertia and absorptive capacity (AC) theories are the theoretical underpinning...
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Hysteresis modelling of a medium frequency single-phase transformer
PublicationThe article describes a feedback Preisach hysteresis model equivalent circuit implementation of a medium frequency single-phase transformer being a part of a high power and high efficiency DC-DC converter. The macroscopic models of magnetic hysteresis are introduced and the feedback Preisach model is selected for further analysis. The hysteresis model is developed for a prototype transformer and the hysteresis loops are compared...
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Modelling of planar movement dynamics of upper limb
PublicationThe original model describing planar movement dynamics of upper limb is presented. The upper limb is modelled as two-joints system loaded by external forces and internal forces of striated skeletal muscles. A behaviour of each muscle is modelled as a system composed of serially linked rheologic fragments that have different mechanical properties. These muscle models allow us to simulate a behaviour of short fusiform muscle (3DOF...
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Analysis of inductive power transfer systems for variable air gap and voltage supply frequency
PublicationThe paper describes an IPT system, by which electrical energy may be transmitted through a large air gap between coils without electrical connection. It presents theoretical and simulation analysis of IPT, which allows for supplying a receiver in the conditions of slow, in relation to the dynamics of power supply, changes in dimension of the air gap. The influence of frequency characteristics of the system on the possible selection...
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Metody usuwania zakłóceń podczas pomiarów polowych widm Ramana
PublicationW pracy zostały scharakteryzowane źródła zakłóceń występujące podczas pomiarów widm Ramana w warunkach polowych oraz sposoby redukcji ich wpływu na jakość rejestrowanych widm. Zaprezentowano wpływ czasu integracji na jakość rejestrowanych widm w przypadkach, gdy szumy własne spektrometru mają składową typu 1/f, dominującą w zakresie małych częstotliwości. Przedstawiono także wyniki uzyskane podczas pomiarów z detekcją synchroniczną,...
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A new approach to active noise and vibration control - [Part II: unknown frequency case]
PublicationThis paper presents a new approach to rejection of complex-valued sinusoidal disturbances acting at the output of a discrete-time stable linear plant with unknown and possibly timevarying dynamics. It is assumed that both the instantaneous frequency of the sinusoidal disturbance and its amplitude may be slowly varying with time and that the output signal is contaminated with wideband measurement noise. It is not assumed that a...
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Measurements of relative frequency instability
PublicationFrequency constancy can be determined by the change in time for the subsequent periods. The article shows that classical the method of digital period measurement is not suitable for the measurement process. Therefore, a method using an integrating circuit is being proposed. Errors in the measurement of the given method have been analyzed.
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Investigation of the laser generated ablation plasma plume dynamics and plasma plume sound wave dynamics
PublicationWe investigated the dynamics of laser generated ablation plasma plume expanding in ambient air and dynamics of the sound wave generated by the expanding plasma. The ablation plasma plume was generated during nanosecond laser micromachining of the thin metal foil. The time-resolved images of the expanding plasma plume and sound wave were captured at several nanosecond intervals. Using captured images the expansion rate of the plasma...
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On dynamics of origami-inspired rod
PublicationWe discuss the dynamics of a relatively simple origami-inspired structure considering discrete and continuum models. The latter was derived as a certain limit of the discrete model. Here we analyze small in-plane deformations and related equations of infinitesimal motions. For both models, dispersion relations were derived and compared. The comparison of the dispersion relations showed that the continuum model can capture the behavior...
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Automatic Optimization Of Adaptive Notch Filter’s Frequency Tracking
PublicationEstimation of instantaneous frequency of narrowband com- plex sinusoids is often performed using lightweight algo- rithms called adaptive notch filters. However, to reach high performance, these algorithms require careful tuning. The paper proposes a novel self-tuning layer for a recently intr o- ducedadaptive notch filtering algorithm. Analysis shows th at, under Gaussian random-walk type assumptions, the resultin g solution converges...
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Self-tuning adaptive frequency tracker
PublicationAn automatic gain tuning algorithm is proposed for a recently introduced adaptive notch filter. Theoretical analysis and simulations show that, under Gaussian random-walk type assumptions, the proposed extension is capable of adjusting adaptation gains of the filter so as to minimize the mean-squared frequency tracking error without prior knowledge of the true frequency trajectory. A simplified one degree of freedom version of...
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Dynamics of algae growth and nutrients in experimental enclosures culturing bighead carp and common carp: Phosphorus dynamics
PublicationThis is the third paper of the series about “Dynamics of algae growth and nutrients in experimental enclosures culturing bighead carp and common carp”. In this paper, phosphorus dynamics were investigated under the condition of culturing bighead carp and common carp with added fish food (nitrogen dynamics is discussed in the second paper because their behaviors are so different from each other). Nearly fifty days’ observation results...
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A Compact Basis for Reliable Fast Frequency Sweep via the Reduced-Basis Method
PublicationA reliable reduced-order model (ROM) for fast frequency sweep in time-harmonic Maxwell’s equations by means of the reduced-basis method is detailed. Taking frequency as a parameter, the electromagnetic field in microwave circuits does not arbitrarily vary as frequency changes, but evolves on a very low-dimensional manifold. Approximating this low-dimensional manifold by a low dimension subspace, namely, reduced-basis space, gives...
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Extending the Frequency Limit of Microstrip-Coupled CSRR Using Asymmetry
PublicationAbstract— This article explains the frequency limitation in designing microstrip circuits based on a complementary split-ring resonator (CSRR) and reports a novel technique for increasing its operating frequency, which makes the CSRR suitable for high-frequency applications. This study helps in synthesizing the dimensions of symmetric CSRR (SCSRR) and asymmetric CSRR (ACSRR) circuits, which shows the applicability of the proposed...
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A fast time-frequency multi-window analysis using a tuning directional kernel
PublicationIn this paper, a novel approach for time-frequency analysis and detection, based on the chirplet transform and dedicated to non-stationary as well as multi-component signals, is presented. Its main purpose is the estimation of spectral energy, instantaneous frequency (IF), spectral delay (SD), and chirp rate (CR) with a high time-frequency resolution (separation ability) achieved by adaptive fitting of the transform kernel. We...
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Soft – Partial Frequency Reuse Method for LTE-A
PublicationIn the paper a novel SPFR frequency reuse method is proposed which can be used for improvement of physical resources utilization efficiency in LTE-A. The proposed method combines both SFR and PFR giving the possibility of more flexible use of frequency band in different regions of a cell. First, a short study on the problem of frequency reuse in cells is discussed including bibliography overview....
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Roadmap on dynamics of molecules and clusters in the gas phase
PublicationThis roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics of molecules and clusters in the gas phase. It comprises nineteen contributions by scientists with leading expertise in complementary experimental and theoretical techniques to probe the dynamics on timescales spanning twenty orders of magnitudes, from attoseconds to minutes and beyond, and for systems ranging in complexity...
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Periodic and chaotic dynamics in a map‐based neuron model
PublicationMap-based neuron models are an important tool in modeling neural dynamics and sometimes can be considered as an alternative to usually computationally costlier models based on continuous or hybrid dynamical systems. However, due to their discrete nature, rigorous mathematical analysis might be challenging. We study a discrete model of neuronal dynamics introduced by Chialvo in 1995. In particular, we show that its reduced one-dimensional...
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Molecular dynamics studies of polyurethane nanocomposite hydrogels
PublicationPolyurethane PEO-based hydrogels have a broad range of biomedical applicability. They are attractive for drug-controlled delivery systems, surgical implants and wound healing dressings. In this study, a PEO based polyurethane hydrogels containing Cloisite R 30B, an organically modified clay mineral, was synthesized. Structure of nanocomposite hydrogels was determined using XRD technique. Its molecular dynamics was studied by means...
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Recognizing emotions on the basis of keystroke dynamics
PublicationThe article describes a research on recognizing emotional states on the basis of keystroke dynamics. An overview of various studies and applications of emotion recognition based on data coming from keyboard is presented. Then, the idea of an experiment is presented, i.e. the way of collecting and labeling training data, extracting features and finally training classifiers. Different classification approaches are proposed to be...
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Parallel frequency tracking with built-in performance evaluation
PublicationThe problem of estimation of instantaneous frequency of a nonstationary complex sinusoid (cisoid) buried in wideband noise is considered. The proposed approach employs a bank of adaptive notch filters, extended with a nontrivial performance assessment mechanism which automatically chooses the best performing filter in the bank. Additionally, a computationally attractive method of implementing the bank is proposed. The new structure...
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Utilizing pulse dynamics for non-invasive Raman spectroscopy of blood analytes
PublicationNon-invasive measurement methods offer great benefits in the field of medical diagnostics with molecular-specific techniques such as Raman spectroscopy which is increasingly being used for quantitative measurements of tissue biochemistry in vivo. However, some important challenges still remain for label-free optical spectroscopy to be incorporated into the clinical laboratory for routine testing. In particular, non-analyte-specific...