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Search results for: TIME- FREQUENCY ANALYSIS
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Independent dynamics of low, intermediate, and high frequency spectral intracranial EEG activities during human memory formation
PublicationA wide spectrum of brain rhythms are engaged throughout the human cortex in cognitive functions. How the rhythms of various frequency ranges are coordinated across the space of the human cortex and time of memory processing is inconclusive. They can either be coordinated together across the frequency spectrum at the same cortical site and time or induced independently in particular bands. We used a large dataset of human intracranial...
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Performance-Driven Surrogate Modeling of High-Frequency Structures
PublicationThe development of modern high-frequency structures, including microwave and antenna components, heavily relies on full-wave electromagnetic (EM) simulation models. Notwithstanding, EM-driven design entails considerable computational expenses. This is especially troublesome when solving tasks that require massive EM analyzes, parametric optimization and uncertainty quantification be-ing representative examples. The employment of...
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Recent advances in high-frequency modeling by means of domain confinement and nested kriging
PublicationDevelopment of modern high-frequency components and circuits is heavily based on full-wave electromagnetic (EM) simulation tools. Some phenomena, although important from the point of view of the system performance, e.g., EM cross-coupling effects, feed radiation in antenna arrays, substrate anisotropy, cannot be adequately accounted for using simpler means such as equivalent network representations. Consequently, the involvement...
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An improved frequency estimator for an adaptive active noise control scheme
PublicationAn improved frequency tracker is proposed for the recently introduced self optimizing narrowband interference canceller (SONIC). The scheme is designed for disturbances with quasi-linear frequency modulation and, under second-order Gaussian random-walk assumption, can be shown to be statistically efficient. One real-world experiment and several simulations show that a considerable improvement in disturbance rejection may be achieved...
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Interictal high-frequency oscillations in focal human epilepsy
PublicationPURPOSE OF REVIEW: Localization of focal epileptic brain is critical for successful epilepsy surgery and focal brain stimulation. Despite significant progress, roughly half of all patients undergoing focal surgical resection, and most patients receiving focal electrical stimulation, are not seizure free. There is intense interest in high-frequency oscillations (HFOs) recorded with intracranial electroencephalography as potential...
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Assessment of Supercapacitor’s Quality by Means of Low Frequency Noise
PublicationLow frequency noise is a well-known tool for quality and reliability assessment of electronic devices. This phenomenon is observed in different electrochemical devices as well (e.g., smart windows, electrochemical corrosion processes). Thus, we can assume that the same tool can be used to asses quality of supercapacitors. Their quality is usually determined only by capacitance and/or equivalent series resistance (ESR), or impedance....
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Platforma KASKADA jako system zapewniania bezpieczeństwa poprzez masową analizę strumieni multimedialnych w czasie rzeczywistym
PublicationW artykule przedstawiono Platformę KASKADA rozumianą jako system przetwarzania danych cyfrowych i strumieni multimedialnych oraz stanowiącą ofertę usług wspomagających zapewnienie bezpieczeństwa publicznego, ocenę badań medycznych i ochronę własności intelektualnej. celem prowadzonych prac było stworzenie innowacyjnego systemu umozliwiajacego wydajną i masową analizę dokumentów cyfrowych i strumieni multimedialnych w czasie rzeczywistym...
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Improved method for real-time speech stretching
Publicationn algorithm for real-time speech stretching is presented. It was designed to modify input signal dependently on its content and on its relation with the historical input data. The proposed algorithm is a combination of speech signal analysis algorithms, i.e. voice, vowels/consonants, stuttering detection and SOLA (Synchronous-Overlap-and-Add) based speech stretching algorithm. This approach enables stretching input speech signal...
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Simulation of the weight averaging of pulse frequency modulated sensor output signal
Open Research DataThe aim of the research is investigation of the efficiency of weight averaging of pulse frequency modulated signal. It was shown that from the point of view of the reduction of the sampling error the best are polynomial weighing functions, for which the maximum of this component error decreases proportionally to the appropriate power of the number of...
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Frequency based criterion for distinguishing tonal and noisy spectral components
PublicationA frequency-based criterion for distinguishing tonal and noisy spectral components is proposed. For considered spectral local maximum two instantaneous frequency estimates are determined and the difference between them is used in order to verify whether component is noisy or tonal. Since one of the estimators was invented specially for this application its properties are deeply examined. The proposed criterion is applied to the...
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METHODS OF QUANTITATIVE ANALYSIS (TEAM PROJECT) (2022/2023)
e-Learning CoursesMETHODS OF QUANTITATIVE ANALYSIS (TEAM PROJECT) - Economic Analytics, Lecture and Lab, Winter Semester 2022/2022. Teacher: dr Piotr Paradowski
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Frequency-dependent coupling model for microwave band-pass filter
PublicationThe goal of this work was to create a circuit model which represents frequency-dependent coupling between microwave resonators. Our models are designed for in-line filters. The frequency-dependent coupling enables one to realize a transmission zero which is not possible in classical approach with frequency independent inverters. In addition, the proposed model allows us to observe out-of-band behavior, e.g. spurious resonance....
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Influence of magnetic field on wear in high frequency reciprocatingsliding contacts
PublicationResults of experimental studies concerning the influence of permanent magnetic field on wear of dry sliding contact operating at short stroke and high frequency are presented. It was found that horizontal magnetic field with different orientations relative to the sliding direction is affecting performance of the contact. The increase in frequency of sliding reduces accumulated mass loss and lowers the surface roughness of the wear...
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Modeling by finite element methods of impact of erosion on frequency of normal modes of L-0 blade
PublicationAfter some time of exploitation steam turbine rotors blades in energetic industry they are being eroded and also their frequency of normal modes is changed. Those changes can cause to unwanted shift of blades normal mode frequencies. It is necessary to find quick method of rating changes of frequency in connection of mass loss due erosion. The evaluation of this dependence was made by finite element modeling method using HyperWorks...
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Highly-Miniaturized Microfluidically-Based Frequency Reconfigurable Antenna Diplexer Employing Half-Mode SIRW
PublicationThis article introduces a super-miniaturized frequency reconfigurable antenna diplexer based on microfluidic techniques. The proposed structure is developed using a half-mode substrate-integrated rectangular waveguide (HMSIRW). The antenna architecture consists of two HMSIRW cavities loaded with L-shaped slots, which are excited by two microstrip feedlines to realize two distinct radiating frequency bands. The footprint of the...
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High frequency oscillations in human memory and cognition: a neurophysiological substrate of engrams?
PublicationDespite advances in understanding the cellular and molecular processes underlying memory and cognition, and recent successful modulation of cognitive performance in brain disorders, the neurophysiological mechanisms remain underexplored. High frequency oscillations beyond the classic electroencephalogram spectrum have emerged as a potential neural correlate of fundamental cognitive processes. High frequency oscillations are detected...
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On the deformation and frequency analyses of SARS-CoV-2 at nanoscale
PublicationThe SARS-CoV-2 virus, which has emerged as a Covid-19 pandemic, has had the most significant impact on people's health, economy, and lifestyle around the world today. In the present study, the SARS-CoV-2 virus is mechanically simulated to obtain its deformation and natural frequencies. The virus under analysis is modeled on a viscoelastic spherical structure. The theory of shell structures in mechanics is used to derive the governing...
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Selected aspects of modern X-ray structural analysis 2024
e-Learning CoursesSelected Aspects of Modern X-ray Structural Analysis
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Selected Aspects of Modern X-ray Structural Analysis 2023
e-Learning CoursesSelected Aspects of Modern X-ray Structural Analysis
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Time-domine Dipole Fields in acoustic and Elektromagnetics
PublicationThe ultrawideband (UWB) radio technique presents a challenge not just for technology. The UWB carrier-free pulses act at a close distance, their electromagnetic fields being very different from classic monochromatic plane wave. The author proposes to adapt a time-domian approach to analysis of broadband spherical fields, both acoustic and electromagnetic, in fundamental cases of quasi-point physical sources.
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Dew and hoarfrost frequency, formation efficiency and chemistry in Wroclaw, Poland
PublicationThis article presents the results of a research study concerning a comparison of frequency, formation efficiency and basic physico-chemical properties of dew and hoarfrost in urban conditions. Longer than two-year series of measurements was carried out from 1 February 2008 to 10 March 2010 in Wroclaw, Poland. Sampling of atmospheric deposits was made by means of insulated plain passive radiative condensers, which allowed to collect...
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Adaptacja akustyczna pomieszczenia wykładowego - studium przypadku
PublicationW niniejszej pracy przedstawiono analizę rozkładu pola akustycznego sali wykładowej znajdującej się w budynku Wydziału Elektroniki i Telekomunikacji Politechniki Gdańskiej. Badania przeprowadzono metodą pomiarową oraz symulacyjną z wykorzystaniem programu Odeon. Wybór parametrów oceny akustyki wnętrz sugerowany jest wymaganiami stawianymi pomieszczeniom lekcyjnym z zaznaczeniem multimedialnego charakteru wykładów prowadzonych...
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[ITiT] Transmission Channel in Radio Communication Systems - 2023/2024
e-Learning Courses{mlang pl} Dyscyplina: informatyka techniczna i telekomunikacja Zajęcia fakultatywne dla doktorantów II roku Prowadzący: dr hab. inż. Sławomir Ambroziak, prof. PG Liczba godzin: 15 Forma zajęć: wykład {mlang} {mlang en} Discipline: technical informatics and telecommunications Elective course for 2nd-year PhD students Academic teachers: dr hab. inż. Sławomir Ambroziak, prof. PG Total hours of training: 15 teaching hours Course...
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[ITiT] Transmission Channel in Radio Communication Systems
e-Learning Courses{mlang pl} Dyscyplina: informatyka techniczna i telekomunikacja Zajęcia fakultatywne dla doktorantów II roku Prowadzący: dr hab. inż. Sławomir Ambroziak, prof. PG Liczba godzin: 15 Forma zajęć: wykład {mlang} {mlang en} Discipline: technical informatics and telecommunications Elective course for 2nd-year PhD students Academic teachers: dr hab. inż. Sławomir Ambroziak, prof. PG Total hours of training: 15 teaching hours Course...
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Generalized Chebyshev Bandpass Filters With Frequency-Dependent Couplings Based on Stubs
PublicationThis paper presents an accurate synthesis method for inline and cross-coupled generalized Chebyshev bandpass filters with frequency-dependent couplings implemented via open and short stubs. The technique involves the synthesis of a lumped-element prototy pe in the form of a coupling matrix with a frequency-dependent term and the conversion of this prototype to a distributed-element mode l composed of sections of TEM lines. This...
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Bypass kolejowy dla wiaduktu łukowego i kratownicowego w ciągu modernizowanej linii kolejowej E59 na odcinku Wronki – Dobiegniew
PublicationW artykule przedstawiono realizacje bypassu kolejowego, zlokalizowanego nieopodal miejscowości Krzyż Wielkopolski w ciągu linii kolejowej E59 na skrzyżowaniu z linią kolejową 203. Wariantowa analiza kilku zaproponowanych rozwiązań wykazała, ze wykonstruowanie bypassu na czas prowadzenia prac modernizacyjnych pozwoli na utrzymanie ciągłości ruchu kolejowego, nie stworzy nadmiernych problemów podróżnym, a jednocześnie pozwoli na...
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Początek Gdyńskiego Systemu Wodociągowego Planowanie i budowa lokalnego układu wodociągowego na Kępie Oksywskiej (1929 – 1932. Część II.
PublicationUdokumentowanie procesu inwestycyjnego przekształcenia wodociągu wiejskiego w miejski układ wodociągowy na podstawie analizy materiałów źródłowych. Ustalenie hydrogeologicznych uwarunkowań decyzji o lokalizacji ujęcia wody „Oksywie”. Identyfikacja parametrów konstrukcyjnych i kosztów budowy trzech budynków na ujęciu wody: mieszkalnego, stacji pomp i odżelaziania wody. Odtworzenie przebiegu budowy struktury sieci wodociągowej w...
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PORÓWNANIE EFEKTYWNOŚCI DZIAŁALNOŚCI BADAWCZO ROZWOJOWEJ W KRAJACH OECD
PublicationEfektywność działalności badawczo-rozwojowej powinna być w centrum zainteresowania decydentów we wszystkich krajach. Kluczowe jest stworzenie możliwości pomiaru efektywności działań w tym obszarze. Celem artykułu jest porównanie efektywności realizacji polityki działalności badawczo-rozwojowej w krajach OECD, wykorzystując metodę Data Envelopment Analysis. Podkreślono problem heterogeniczności grupy porównywanych krajów. Zastosowano...
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Differential inequalities with initial time difference.
PublicationUzyskano pewne wyniki porównawcze pomiędzy rozwiązaniami nierówności różniczkowych startujących z różnych punktów początkowych. O nieliniowej funkcji f (związanej z zagadnieniem) zakładano jednostronny warunek Lipschitza. Podano pewne zastosowanie otrzymanych wyników. Sformułowano też pewne warunki dotyczące stabilności.
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High frequency impulse ground penetrating radar application in assessment of interlayer connections
PublicationGround Penetrating Radar (GPR) technique is commonly used in the nondestructive evaluation of pavement structures. In particular, this method is used to estimate thicknesses of pavement layers as well as it can be utilized in advanced studies of pavement structures. The device presented in this paper comprise the high frequency impulse antennas that allow for investigating the interlayer zones in terms of their electromagnetic...
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Rola i znaczenie zbiornika sieciowego w kształtowaniu hydrauliki i jakości wody w systemie wodociągowym
PublicationEksploatacja zbiornika sieciowego powinna zapewniać cykliczną wymianę wody w jego komorach. Koniecznym warunkiem prawidłowej eksploatacji zbiornika jest zgodność założeń projektowych ze stanem faktycznym. Praktyka eksploatacyjna wskazuje na szereg nieprawidłowości w tym względzie. Z powodu lokalizacji zbiornika sieciowego za nisko lub za wysoko albo wskutek błędów popełnionych w ustaleniu jego parametrów obserwuje się niestabilność...
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Fundamentals of microscopic analysis
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Dynamic mass measurement in checkweighers using a discrete time-variant low-pass filter
PublicationConveyor belt type checkweighers are complex mechanical systems consisting of a weighing sensor (strain gauge load cell, electrodynamically compensated load cell), packages (of different shapes, made of different materials) and a transport system (motors, gears, rollers). Disturbances generated by the vibrating parts of such a system are reflected in the signal power spectra in a form of strong spectral peaks, located usually in...
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High frequency oscillations are associated with cognitive processing in human recognition memory
PublicationHigh frequency oscillations are associated with normal brain function, but also increasingly recognized as potential biomarkers of the epileptogenic brain. Their role in human cognition has been predominantly studied in classical gamma frequencies (30-100 Hz), which reflect neuronal network coordination involved in attention, learning and memory. Invasive brain recordings in animals and humans demonstrate that physiological oscillations...
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An Extremely Compact Frequency Reconfigurable Antenna Diplexer Employing Dielectric Liquids
PublicationThe letter presents an extremely compact frequency reconfigurable antenna diplexer based on fluidic channels for sub6 GHz applications. The proposed antenna diplexer is modelled by employing half-mode (HM) and quarter-mode (QM) substrateintegrated rectangular cavities, two slots, orthogonal feed lines, and fluidic vias. To comprehend the radiation mechanism, the equivalent circuit, electric field distributions, and frequency responses...
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A new method for real-time monitoring of volatiles in frying fumes using proton transfer reaction mass spectrometry with time-of-flight analyse
PublicationTo safeguard the consumers’ well-being, it is necessary to develop novel methods for determination of carcinogens in food, including volatiles generated during frying. The currently used procedures for analysis of volatile fraction of vegetable oils are not based on real-time measurements and thus do not enable the determination of carcinogenic compounds in frying fumes; instead, only the headspace or liquid fraction is sampled....
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Liquid residence time in vortex separators
PublicationCentrifugal force enhances gravitational separation of suspension (vortex separators), as well as allows regulation of liquid discharge (vortex flow controls). Furthermore, it elongates the effective residence time of liquid inside the chamber in comparison to non-circulative flow. Laboratorz measurements, described in the paper, indicate that average liquid residence time for circulative flow exceeds 50% of plug-flow time,...
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Tripping of F-type RCDs for High-Frequency Residual Currents
PublicationResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs...
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Tripping of F-type RCDs for high-frequency residual currents
PublicationResidual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs are...
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A Linear Phase Filter in Quadruplet Topology With Frequency-Dependent Couplings
PublicationThis letter presents a design of a linear phase microwave bandpass filter. The filter is composed of four resonators arranged in the quadruplet topology. Making the cross and one direct coupling dispersive gives additional design flexibility. The first advantage of using frequency-dependent couplings is the possibility to chose an arbitrary location of a pair of complex transmission zeros (TZs) in the s-domain. The second one is...
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Accurate design of pseudoelliptic inline SIW filters with frequency-dependent couplings
PublicationThis paper presents an accurate synthesis method for inline SIW (Substrate Integrated Waveguide) generalized Chebyshev bandpass filters with frequency-dependent couplings. The technique is based on the synthesis of a coupling matrix that takes into account the impedance of the frequency-dependent stub. Thus, a loading effect compensation in adjacent resonators (via resonant frequency adjustment) and coupling elements (via coupling-value...
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Throughput-Coverage Characteristics for Soft and Partial Frequency Reuse in the LTE Downlink
PublicationThe paper presents results of simulation and evaluation of throughput-coverage characteristics for the OFDMA-based LTE network with Soft Frequency Reuse or Partial Frequency Reuse. Firstly, simulation results of throughput characteristics for a single user connection are presented, which allow the evaluation of the stability and availability of bit rate achieved in different areas of a cell. Secondly, the capacity characteristics...
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High Frequency Harmonics Emission of Modern Power Electronic AC-DC Converters
PublicationModern AC/DC converters with bidirectional power flow employing PWM boost topology generate harmonic distortions of input current in relatively high frequency range tightly related to modulation carrier frequency. These frequencies and its multiples in typical applications are usually located in frequency range from single up to several of kHz. Increased harmonic emission in this frequency range can easily and harmfully influence...
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Speech formant frequency and pitch estimation using instantaneous complex frequency
PublicationW pracy opisany został algorytm estymacji częstotliwości podstawowej oraz częstotliwości środkowych i pasm formantów mowy z wykorzystaniem zespolonej pulsacji chwilowej. W artykule przedstawiono również wyniki działania algorytmu dla polskich samogłosek.
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Low frequency nois of supecapacitor
Open Research DataDataset contains results of low frequency noise observation during discharge of commercially available supercapacitor, type DRL 2.7V 10F, with a nominal capacitance 10 F and a nominal voltage 2.7 V. Supercapacitor was charged to various voltages and discharged through a resistor. In the experiment the 50 Ohm and 200 Ohm resistors were used. The supercapacitor...
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Determination of Mathematical Model Parameters of a Medium Frequency Transformer
PublicationThe paper presents the results of experimental studies of the medium frequency transformer. The object of the research was a prototype of a single-phase transformer with a core made of ferrite I-core elements and windings made of Litz conductors. The research was carried out to determine the parameters of the transformer's mathematical model. The scope of the tests included determining the magnetic hysteresis loop and measuring...
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Audible noise in ship’s electrical drive systems with frequency converters
Open Research DataThe presented dataset is part of research focusing on the impact of the ship's electrical drive systems with frequency converters on vibrations and the level of audible noise on ships.
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Journal of Time Series Econometrics
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KronoScope-Journal for the Study of Time
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Journal of Time Use Research
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