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Wyniki wyszukiwania dla: TIME DELAY ESTIMATION
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Time Delay Estimation in Two-Phase Flow Investigation Using the γ-Ray Attenuation Technique.
PublikacjaTime delay estimation is an important research question having many applications in a range of technologies. Measurement of a two-phase flow in a pipeline or an open channel using radioisotopes is an example of such application. For instance, the determination of velocity of dispersed phase in that case is based on estimation of the time delay between two stochastic signals provided by scintillation probes. The proper analysis...
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Parameter and delay estimation of linear continuous-time systems
PublikacjaIn this paper the problem of on-line identification of non-stationary delay systems is considered. Dynamics of supervised industrial processes is described by ordinary differential equations. Discrete-time mechanization of their continuous-time representations is based on dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures implemented in recursive forms are applied for simultaneous identification...
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Parameter and delay estimation of linear continuous-time systems
PublikacjaIn this paper the problem of on-line identification of non-stationary delay systems is considered. Dynamics of supervised industrial processes is usually described by ordinary differential equations. Discrete-time mechanization of their continuous-time representations is based on dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures implemented in recursive forms are applied for simultaneous...
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On–line Parameter and Delay Estimation of Continuous–Time Dynamic Systems
PublikacjaThe problem of on-line identification of non-stationary delay systems is considered. The dynamics of supervised industrial processes are usually modeled by ordinary differential equations. Discrete-time mechanizations of continuous-time process models are implemented with the use of dedicated finite-horizon integrating filters. Least-squares and instrumental variable procedures mechanized in recursive forms are applied for simultaneous...
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High performance super-twisting sliding mode control for a maritime autonomous surface ship (MASS) using ADP-Based adaptive gains and time delay estimation
PublikacjaThis research addresses two kinds of problems related to optimal trajectory tracking of a Maritime Autonomous Surface Ship (MASS): those caused by the time-varying external disturbances including winds, waves and ocean currents as well as those resulting from inherent dynamical uncertainties. As the paper shows, an accurate and robust optimal controller can successfully deal with both issues. An improved Optimal Adaptive Super-Twisting...
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High performance super-twisting sliding mode control for a maritime autonomous surface ship (MASS) using ADP-Based adaptive gains and time delay estimation
PublikacjaThis research addresses two kinds of problems related to optimal trajectory tracking of a Maritime Autonomous Surface Ship (MASS): those caused by the time-varying external disturbances including winds, waves and ocean currents as well as those resulting from inherent dynamical uncertainties. As the paper shows, an accurate and robust optimal controller can successfully deal with both issues. An improved Optimal Adaptive Super-Twisting...
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Delay differential inequalities with initial time difference
PublikacjaPraca dotyczy nierówności różniczkowych z argumentami opóźnionymi przy różnych warunkach początkowych. Podano twierdzenia porównawcze dla takich nierówności. Podano też warunki dostateczne na istnienie ekstremalnych rozwiązań odpowiednich równań różniczkowych z argumentami opóźnionymi.
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Accuracy of Differential Phase Delay Estimation for GPS Spoofing Detection
PublikacjaGPS spoofing is an attack based on transmission of false signals to target receivers, in order to force the computation of incorrect time, position or velocity information. It is a threat which is recently considered with continuously growing awareness. There is a need for effective way of GPS spoofing detection. Many groups of methods are proposed in the literature. Spatial processing methods are considered to be robust in a wide...
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Discrete-time estimation of nonlinear continuous-time stochastic systems
PublikacjaIn this paper we consider the problem of state estimation of a dynamic system whose evolution is described by a nonlinear continuous-time stochastic model. We also assume that the system is observed by a sensor in discrete-time moments. To perform state estimation using uncertain discrete-time data, the system model needs to be discretized. We compare two methods of discretization. The first method uses the classical forward Euler...
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Discrete-time estimation of nonlinear continuous-time stochastic systems
PublikacjaIn this paper we consider the problem of state estimation of a dynamic system whose evolution is described by a nonlinear continuous-time stochastic model. We also assume that the system is observed by a sensor in discrete-time moments. To perform state estimation using uncertain discrete-time data, the system model needs to be discretized. We compare two methods of discretization. The first method uses the classical forward Euler...
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Continuous-time delay system identification insensitive to measurement faults
PublikacjaW pracy wykorzystuje się algorytmy identyfikacji do estymacji parametrów systemów ciągłych z opóźnieniem. Zastosowanie filtrów całkujących ze skończonym horyzontem obserwacji pozwala przekształcić równanie różniczkowe opisujące system ciągły do użytecznej postaci regresyjnej z czasem dyskretnym. Uzyskany w ten sposób i zachowujący oryginalną parametryzację model dyskretny daje się identyfikować stosując klasyczną metodę najmniejszych...
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Delay integro-differential inequalities with initial time difference and applications.
PublikacjaPraca dotyczy nierówności różniczko-całkowych z opóźnionymi argumentami przy różnych warunkach początkowych. Przy pewnych założeniach (m.in. monotoniczność, jednostronny warunek Lipschitza) sformułowano twierdzenia porównawcze dla rozwiązań w.w nierówności. Pokazano zastosowania w technice iteracji monotonicznych i sformułowano warunki dostateczne na istnienie rozwiązań ekstremalnych dla równań różniczkowo-całkowych z odchylonymi...
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Comments on “Closed Form Variable Fractional Time Delay Using FFT”
PublikacjaIn this letter drawbacks of the aforementioned paper are pointed out. The proposed approach is improved with minor modifications of the discrete frequency response. This allows for design of fractional delay filters which are close to optimal and can be efficiently implemented in the frequency domain using the sliding DFT based structure. Alternatively, the derived equivalent closed form formulae for offset windows can be used...
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Determination of time delay between ventricles contraction using impedance measurements
PublikacjaThe paper presents a novel approach to assessment of ventricular dyssynchrony basing on multichannel electrical impedance measurements. Using a proper placement of electrodes, the sensitivity approach allows estimating time difference between chambers contraction from over determined nonlinear system of equations. The theoretical considerations which include Finite Element Method simulations were verified using measurements on...
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Travel Time of Public Transport Vehicles Estimation
PublikacjaEffective prediction of speed is central to advanced traveler information and transportation management systems. The speed of public transport vehicles is affected by many external factors including traffic volume, organization and infrastructure. The literature presents methods for estimating travel time on sections of a transport network and vehicle arrival at stops, often making use of the AVL (automatic vehicle location). The...
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Chirp-rate estimation of FM signals in the time-frequency domain
PublikacjaNovel dynamic representations of a complex signal in the time-frequency domain including: a channelized instantaneous complex frequency (CICF), a complex local group delay (CLGD) and a channelized instantaneous chirp-rate (CICR) are introduced. The proposed approach is based on the use of the gradient of the short-time Fourier transform complex phase. An interpretation of the newly-introduced distributions especially of the CICR...
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Asynchronous Networked Estimation System for Continuous Time Stochastic Processes
PublikacjaIn this paper we examine an asynchronous networked estimation system for state estimation of continuous time stochastic processes. Such a system is comprised of several estimation nodes connected using a possibly incomplete communication graph. Each of the nodes uses a Kalman filter algorithm and data from a local sensor to compute local state estimates of the process under observation. It also performs data fusion of local estimates...
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Asynchronous distributed state estimation for continuous-time stochastic processes
PublikacjaWe consider the problem of state estimation of a continuous-time stochastic process using an asynchronous distributed multi-sensor estimation system (ADES). In an ADES the state of a process of interest is estimated by a group of local estimators. Each local estimator based, for example, on a Kalman filter, performs single sensor filtration but also fusion of its local results and results from other (remote) processors to compute...
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Statistically efficient smoothing algorithm for time-varying frequency estimation
PublikacjaThe problem of extraction/elimination of a nonstationary sinusoidal signal 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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Investigations of the Methods of Time Delay Measurement of Stochastic Signals Using Cross-correlation with the Hilbert Transform
PublikacjaThe article presents the results of simulation studies of four methods of estimating time delay for random signals using cross-correlation with the Hilbert Transform. Selected models of mutually delayed stochastic signals were used in the simulations, corresponding to the signals obtained from scintillation detectors in radioisotope measurements of liquid-gas two-phase flow. Standard deviations of the values of the individual functions...
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A Meta-Analysis of Pulse Arrival Time Based Blood Pressure Estimation
PublikacjaThe paper presents a preliminary meta-analysis of the sample correlation between pulse arrival time (PAT) and blood pressure (BP). The aim of the study was to verify sample correlation coefficient between PAT and BP using an affine model BP = a · P AT + b for systolic and diastolic blood pressure. The databases included in the search were the IEEE Xplore Digital Library, Springer Link and Google Scholar. Only papers from 2005 to...
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Non-quadratic quality criteria in parameter estimation of continuous-time models
PublikacjaW pracy wykorzystuje się procedury estymacji parametrycznej do identyfikacji modeli z czasem ciągłym. Rozważane algorytmy minimalizują wskaźnik jakości w postaci sumy lub całki wartości bezwzględnej błędu predykcji. Zastosowanie techniki zmiennych instrumentalnych umożliwia ponadto znaczące polepszenie dokładności ocen parametrów, a wprowadzony do w procedur estymacji mechanizm ważenia błędów predykcji pozwala identyfikować modele...
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Asynchronous distributed state estimation based on a continuous-time stochastic model
PublikacjaW artykule rozważa się ogólny problem estymacji stanu w asynchronicznych rozłożonych systemach (ADE) opartych na wielu czujnikach. W takich systemach stan obiektu jest oceniany przez grupę lokalnych estymatorów, z których każdy oparty zwykle na filtrze Kalmana, dokonuje fuzji danych zebranych poprzez jego lokalne czujniki oraz danych uzyskanych od innych (zdalnych) procesorów, w celu wyznaczenia możliwie najlepszych estymat. Przeprowadzając...
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Asynchronous distributed state estimation based on a continuous-time stochastic model
PublikacjaW artykule rozważa się problem estymacji stanu w asynchronicznych rozłożonych systemach (ADE) opartych na wielu czujnikach pomiarowych. W systemach takich stan obiektu jest oceniany przez grupę lokalnych estymatorów, z których każdy (oparty zwykle na filtrze Kalmana) dokonuje fuzji danych zebranych poprzez jego lokalne czujniki oraz danych odebranych od innych zdalnych procesorów, w celu wyznaczenia możliwie najlepszych estymat....
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Asynchronous distributed state estimation based on a continuous time stochastic model
PublikacjaGłównym zadaniem systemu estymacji jest szacowanie stanu obserwowanego obiektu. W rozproszonych wieloczujnikowych systemach estymacji stan obiektu jest estymowany przez pewien zbiór estymatorów lokalnych. Każdy estymator lokalny wykonuje filtrację (np opartą na filtracji Kalmana) danych pochodzących ze skojarzonego z nim czujnika bądź czujników oraz fuzję przetworzonych danych z czujników z danymi pochodzącymi z innych lokalnych...
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Estimation of optical parameters of highly scattering materials by time-of-flight spectroscopy.
PublikacjaPrzedstawiono metody wyznaczania podstawowych parametrów materiałów silnie rozpraszających światło na podstawie pomierzonego rozkładu czasu przelotu krótkich impulsów laserowych. W algorytmie wykorzystano metodę Monte Carlo i metodę dyfuzji do opisu propagacji światła. Oszacowano dokładność oszacowywania tych parametrów.
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Discrete-time predictive control design based on overparameterized delay-plant models and identified cancellation order.
PublikacjaPraca dotyczy uogólnionego sterowania predykcyjnego (GPC) obiektami opisanymi dyskretnoczasowymi modelami CARIMA z uproszczeniami (nieminimalnych, przeparametryzowanych) oraz o niezerowym opóźnieniu transportowym. Optymalne sterowanie predykcyjne wyznacza się na podstawie minimalnowariancyjnego oszacowania przyszłej odpowiedzi sterowanego obiektu. Poprzez analizę warunków rozwiązywalności zadania syntezy sterownika GPC, sformułowano...
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A Time Delay Controller Included Terminal Sliding Mode and Fuzzy Gain Tuning for Underwater Vehicle-Manipulator Systems
PublikacjaAn improved Time Delay Control (TDC) method for an Underwater Vehicle-Manipulator System (UVMS) is proposed. The proposed controller consists of three terms: a time-delay-estimation term that cancels nonlinearities of the UVMS dynamics, a Terminal Sliding Mode (TSM) term that provides a fast response and a PID term that reduces the tracking error. In addition the proposed controller uses fuzzy rules to adaptively tune the gains...
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Service time distribution influence on end-to-end call setup delay calculation in networks with Session Initiation Protocol
PublikacjaThe most important GoS parameter for networks with SIP protocol is end-to-end call setup delay. So far there were no coherent models allowing calculation of these parameters for networks with SIP protocol. Few models were developed but they are insufficient. In the paper we propose model which allows end-to-end call setup delay calculation for networks with SIP protocol. The model is using chain of M/G/1/K models and is applicable...
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Radar Signal Parameters Estimation Using Phase Accelerogram in the Time-Frequency Domain
PublikacjaRadar signal parameter estimation, in the context of the reconstruction of the received signal in a passive radar utilizing other radars as a source of illumination, is one of the fundamental steps in the signal processing chain in such a device. The task is also a crucial one in electronic reconnaissance systems, e.g. ELINT (Electronic Intelligence) systems. In order to obtain accurate results it is important to measure, estimate...
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Closed-Loop Control System Design for Wireless Charging of Low-Voltage EV Batteries with Time-Delay Constraints
PublikacjaThis paper presents an inductive power transfer system on the basis of a double single- phase three-level T-type inverter and two split transmitting coils for constant current and constant voltage wireless charging of low-voltage light electric vehicle batteries with closed-loop control, considering time-delay communication constraints. An optimal control structure and a modified control strategy were chosen and implemented to...
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The Application of Metabolomics in Forensic Science with Focus on Forensic Toxicology and Time-of-Death Estimation
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Single Sensor Hot-Wire Anemometer Based on Thermal Time Constant Estimation
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Closed-Loop Control System Design for Wireless Charging of Low-Voltage EV Batteries with Time-Delay Constraints
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A novel method of local chirp-rate estimation of LFM chirp signals in the time-frequency domain
PublikacjaIn the paper, novel dynamic representations of a complex signal in the time-frequency domain are introduced. The proposed approach is based on using the gradient of the short-time Fourier transform complex phase. A channelized instantaneous complex frequency (CICF) and a complex local group delay (CLGD) are included in the presented signal representations. An application of the newly-introduced distributions is demonstrated by...
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Estimation of time-frequency complex phase-based speech attributes using narrow band filter banks
PublikacjaIn this paper, we present nonlinear estimators of nonstationary and multicomponent signal attributes (parameters, properties) which are instantaneous frequency, spectral (or group) delay, and chirp-rate (also known as instantaneous frequency slope). We estimate all of these distributions in the time-frequency domain using both finite and infinite impulse response (FIR and IIR) narrow band filers for speech analysis. Then, we present...
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Estimation of Conservative Contaminant Travel Time through Vadose Zone Based on Transient and Steady Flow Approaches
PublikacjaEstimation of contaminant travel time through the vadose zone is needed for assessing groundwater vulnerability to pollution, planning monitoring and remediation activities or predicting the effect of land use change or climate change on groundwater quality. The travel time can be obtained from numerical simulations of transient flow and transport in the unsaturated soil profile, which typically require a large amount of data and...
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Robust-adaptive dynamic programming-based time-delay control of autonomous ships under stochastic disturbances using an actor-critic learning algorithm
PublikacjaThis paper proposes a hybrid robust-adaptive learning-based control scheme based on Approximate Dynamic Programming (ADP) for the tracking control of autonomous ship maneuvering. We adopt a Time-Delay Control (TDC) approach, which is known as a simple, practical, model free and roughly robust strategy, combined with an Actor-Critic Approximate Dynamic Programming (ACADP) algorithm as an adaptive part in the proposed hybrid control...
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Improvement of time difference of arrival measurements resolution by using fractional delay filters in a direct sequence-code division multiple access radionavigation system
PublikacjaThis study presents a method of improving time measurements resolution in a direct sequence-code division multiple access receiver by using a fine code tracking loop based on fractional delay filtering of a despreading sequence. It briefly describes the structure of a generic digital code tracking loop and the proposed modification which allows to measure time difference of arrival values with the subsample resolution, together...
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The hybrid estimation algorithm for wastewater treatment plant robust model predictive control purposes at medium time scale
PublikacjaThe paper proposes an approach to designing the hybrid estimation algorithm/module (HEA) with moving measurements window for Wastewater Treatment Plant (WWTP) Robust Model Predictive Control (RMPC) purposes at medium time scale. The RMPC uses a dedicated grey-box model of biological reactor for the system outputs prediction purposes. The grey-box model parameters are dependant on the plant operating point. Hence, these parameters...
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Estimation of wastewater treatment plant state for model predictive control of N-P remowal at medium time scale.
PublikacjaPrzy ograniczonych możliwościach pomiarowych estymaty stanu są potrzebne w sterowaniu optymalizującym, opartym na sterowaniu predykcyjnym, sterującym usuwaniem azotu i fosforu, w biologicznej oczyszczalni ścieków. Optymalizator MPC do implementacji sprzężenia zwrotnego z obiektu potrzebuje tych estymat. Dodatkowo aktualizowane muszą być parametry modelu Gray-Box wykorzystywanego w module MPC. Wtedy estymaty stanu są używane przez...
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Weighted least squares parameter estimation for model predictive control of integrated wastewater systems at medium time scale.
PublikacjaW artykule przedstawione zostało sformułowanie i implementacja algorytmu ważonej sumy najmniejszych kwadratów na przesuwnym oknie pomiarowym dla celów estymacji parametrów modelu typu szara skrzynka. Model typu szara skrzynka dynamiki reaktora biologicznego jest wykorzystywany przez moduł sterowania predykcyjnego sterujący zintegrowanym systemem ściekowym w średniej skali czasu. Algorytm estymacji parametrów był walidowany na symulatorze...
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Metoda energetyczno-czasowa oceny działania poprzecznych łożysk ślizgowych. Energy-time method of the estimation of work of slide bearing
PublikacjaZaproponowano interpretację wartościującą działania, które (podobnie jak przedstawione w mechanice klasycznej działania Hamiltona i Maupertiusa oraz działanie wynikające ze zmiany pędu ciała) jest rozpatrywane jako wielkość fizyczna o jednostce miary zwanej dżulosekundą [dżulxsekunda]. Przedstawiono oryginalną metodę analizy i oceny działania łożyska ślizgowego z uwzględnieniem jego niezawodności i bezpieczeństwa funkcjonowania....
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Set-Bounded joined parameter and state estimation for model predictive control of integrated wastewater treatment plant systems at medium time scale.
PublikacjaW artykule opisano moduł łącznej estymacji w postaci zbiorów ograniczonych (ang. set-bounded) parametrów i stanu systemu dla potrzeb sterowania predykcyjnego zintegrowanym systemem ściekowym w średniej skali czasu. Jest to jeden ze składowych elementów Inteligentnej Hierarchicznej Struktury Sterowania opracowanej w celu pokonania następujących problemów, które występują w kontrolowanym systemie: różne skale czasowe procesów, silnie...
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Uncertainty of Postmortem Time Estimation Based on Potassium Ion Determination in Vitreous Humor Using Potentiometric Ion-Selective Electrode and Microwave-Induced Plasma with Optical Emission Spectrometry Methods
PublikacjaThere is a need for a reliable and independent evaluation and confirmation of the post-mortem interval (PMI) based on objective factors other than only postmortem changes or temperature measurements. Estimating the PMI by examining the concentration of potassium ions in the vitreous humor (VH) has a tradition in forensic toxicology dating back to the mid-20th century. So far, the methods for determining the presence of potassium...
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Probe signal processing for channel estimation in underwater acoustic communication system
PublikacjaUnderwater acoustic communication channels are characterized by a large variety of propagation conditions. Designing a reliable communication system requires knowledge of the transmission parameters of the channel, namely multipath delay spread, Doppler spread, coherence time, and coherence bandwidth. However, the possibilities of its estimation in a realtime underwater communication system are limited, mainly due to the computational...
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On the lower smoothing bound in identification of time-varying systems
PublikacjaIn certain applications of nonstationary system identification the model-based decisions can be postponed, i.e. executed with a delay. This allows one to incorporate in the identification process not only the currently available information, but also a number of ''future'' data points. The resulting estimation schemes, which involve smoothing, are not causal. Assuming that the infinite observation history is available, the paper...
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On ''cheap smoothing'' opportunities in identification of time-varying systems
PublikacjaIn certain applications of nonstationary system identification the model-based decisions can be postponed, i.e. executed with a delay. This allows one to incorporate into the identification process not only the currently available information, but also a number of ''future'' data points. The resulting estimation schemes, which involve smoothing, are not causal. Despite the possible performance improvements, the existing smoothing...
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Assessment of the Impact of GNSS Processing Strategies on the Long-Term Parameters of 20 Years IWV Time Series
PublikacjaAdvanced processing of collected global navigation satellite systems (GNSS) observations allows for the estimation of zenith tropospheric delay (ZTD), which in turn can be converted to the integrated water vapour (IWV). The proper estimation of GNSS IWV can be affected by the adopted GNSS processing strategy. To verify which of its elements cause deterioration and which improve the estimated GNSS IWV, we conducted eight reprocessings...
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Hourly GNSS-derived integrated moisture in the global tropics for the years 2001-2018
Dane BadawczeGlobal tropics are essential in formulating weather patterns and climate across various latitudes through atmospheric teleconnections. Since water vapour is an essential parameter in atmospheric convection and, thus, latent heat release, its tropical variability on different time scales is crucial in understanding weather and climate changes. The provided...