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Search results for: COVARIANCE AND SPECTRUM ESTIMATION.
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On adaptive covariance and spectrum estimation of locally stationary multivariate processes
PublicationWhen estimating the correlation/spectral structure of a locally stationary process, one has to make two important decisions. First, one should choose the so-called estimation bandwidth, inversely proportional to the effective width of the local analysis window, in the way that complies with the degree of signal nonstationarity. Too small bandwidth may result in an excessive estimation bias, while too large bandwidth may cause excessive...
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Estimators of covariance matrices in Msplit(q) estimation
PublicationThis paper proposes methods for the determination of covariance matrices of Msplit(q) estimators. The solutions presented here allow Msplit(q) estimation to be supplemented by the operations from the domain of accuracy analysis (especially that concerning estimators of parameters). Theoretical forms of covariance matrices of Msplit(q) estimators were established using the empirical influence functions and the equivalent covariance...
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Asynchronous distributed state estimation based on covariance intersection
PublicationW artykule rozważa się problem estymacji stanu w rozproszonym systemach wieloczujnikowym. W systemach takich stan obserwowanego obiektu jest estymowany przez pewien zbiór estymatorów lokalnych. Każdy estymator lokalny wykonuje fuzję danych pochodzących ze skojarzonego z nim czujnika lub czujników z danymi pochodzącymi z innych lokalnych estymatorów. W wyniku operacji fuzji oraz dodatkowo operacji filtracji korzystając np. z filtru...
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On autoregressive spectrum estimation using the model averaging technique
PublicationThe problem of estimating spectral density of a nonstationary process satisfying local stationarity conditions is considered. The proposed solution is a two step procedure based on local autoregressive (AR) modeling. In the first step Bayesian-like averaging of AR models, differing in order, is performed. The main contribution of the paper is development of a new final-prediction-error-like statistic, which can be used to select...
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Lattice filter based autoregressive spectrum estimation with joint model order and estimation bandwidth adaptation
PublicationThe problem of parametric, autoregressive model based estimation of a time-varying spectral density function of a nonstationary process is considered. It is shown that estimation results can be considerably improved if identification of the autoregressive model is carried out using the two-sided doubly exponentially weighted lattice algorithm which combines results yielded by two one-sided lattice algorithms running forward in...
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On Adaptive Spectrum Estimation of Multivariate Autoregressive Locally Stationary Processes
PublicationAutoregressive modeling is a widespread parametricspectrum estimation method. It is well known that, in the caseof stationary processes with unknown order, its accuracy canbe improved by averaging models of different complexity usingsuitably chosen weights. The paper proposes an extension of thistechnique to the case of multivariate locally stationary processes.The proposed solution is based on local autoregressive...
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Supply current spectrum estimation of digital cores at early design
PublicationPrzedstawiono nową aproksymacyjną metodę obliczania widma prądu zasilania układów cyfrowych. Metoda oparta jest na charakterystyce impulsów prądowych w kategoriach ich czasu narastania, opadania i długości impulsu. Górną granicę widma (obwiednię) można obliczyć posługując się gęstością prawdopodobieństwa zmian stanu sygnałów w węzłach układu cyfrowego. W odróżnieniu od znanych metod, metoda proponowana wykorzystuje ograniczoną...
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Improving the accuracy of bearing in active sonar with cylindrical array using spectrum estimation.
PublicationThe articles presents a method for improving the accuracy of bearing in multibeam sonar with a cylindrical array. Based on a known spatial spectrum estimation technique, the method has been successfully used in linear array systems. Its accuracy of bearing is satisfactory and ensures a relatively low computational effort. The article discusses certain simplifications and assumptions to adapt the spatial spectrum estimation technique...
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From limits of quantum operations to multicopy entanglement witnesses and state spectrum estimation.
PublicationBadano ograniczenia na nieliniowe transformacje stanu kwantowego. Wprowadzono strukturalne fizyczne przybliżenia niefizycznych odwzorowań liniowych.Zdefiniowano świadków splątania działających na wielu kopiach danego stanu.Pokazano zastosowanie obserwabli kwantowych w detekcji entropii Tsallisa.
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Detection and Direction-of-Arrival Estimation of Weak Spread Spectrum Signals Received with Antenna Array
PublicationThis paper presents a method for the joint detection and direction of arrival (DOA) estimation of low probability of detection (LPD) signals. The proposed approach is based on using the antenna array to receive spread-spectrum signals hidden below the noise floor. Array processing exploits the spatial correlation between phase-delayed copies of the signal and allows us to evaluate the parameter used to make the decision about the...
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Two-Stage Identification of Locally Stationary Autoregressive Processes and its Application to the Parametric Spectrum Estimation
PublicationThe problem of identification of a nonstationary autoregressive process with unknown, and possibly time-varying, rate of parameter changes, is considered and solved using the parallel estimation approach. The proposed two-stage estimation scheme, which combines the local estimation approach with the basis function one, offers both quantitative and qualitative improvements compared with the currently used single-stage methods.
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An adaptive-noise Augmented Kalman Filter approach for input-state estimation in structural dynamics
PublicationThe establishment of a Digital Twin of an operating engineered system can increase the potency of Structural Health Monitoring (SHM) tools, which are then bestowed with enhanced predictive capabilities. This is particularly relevant for wind energy infrastructures, where the definition of remaining useful life is a main driver for assessing the efficacy of these systems. In order to ensure a proper representation of the physical...
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Spectrum Sensing Based on Hybrid Spectrum Handoff in Cognitive Radio Networks
PublicationThe rapid advancement of wireless communication combined with insufficient spectrum exploitation opens the door for the expansion of novel wireless services. Cognitive radio network (CRN) technology makes it possible to periodically access the open spectrum bands, which in turn improves the effectiveness of CRNs. Spectrum sensing (SS), which allows unauthorized users to locate open spectrum bands, plays a fundamental part in CRNs....
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Induction motor bearings diagnostic indicators based on MCSA and normalized triple covariance
PublicationInduction motors are one of the most widely used electrical machines. Statistics of bearing failures of induction motors indicate, that they constitute more than 40% of induction motor damage. Therefore, bearing diagnosis is so important for trouble-free work of induction motors. The most common methods of bearing diagnosis are based on vibration signal analysis. The main disadvantage of those methods is the need for physical access...
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Current-based higher-order spectral covariance as a bearing diagnostic feature for induction motors
PublicationConducting the diagnosis of induction motors remotely by analyzing the supply current is an attractive prospect with the lack of access to the engine. Currently, there is no solution, based on analysis of the current, the credibility of which would allow its use in industry. The statistics of bearing failures in induction motors indicate that they constitute more than 40% of induction motor damage, therefore, bearing diagnosis...
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Covariance approach to the free photon field
PublicationWprowadziliśmy teorię fotonu poprzez tą samą zasadę, co dla pojedynczej czą-stki w kwantowej mechanice używając C*-algebraicznego podejścia kowariantychukładów.
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Lamp of adjustable spectrum for photographic usage
PublicationPhotography is a unique rapidly growing interdisciplinary field encompassing aspects of science, art and technology. Expectations of photographers are steadily increasing with the development of technology. One of the areas playing a crucial role in photography is lighting. Consequently, several types of light sources for photographic use have been developed. The ongoing research in this field concentrates on lamps with tunable...
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Approximation of Covariance Function with Application to Stochastic Mechanics.
PublicationW pracy przedstawiono koncepcję rozwinięć kanonicznych dla funkcji losowych oraz możliwość ich zastosowania w stochastycznej mechanice gruntów. Rozpatrzono rozkład widmowy, rozwinięcia Karhunena-Loevego oraz rozwinięcia ortogonalne zmodyfikowanymi wielomianami Hermite'a. Przeprowadzono analizę błędów dla zagadnienia warstwy gruntu o losowych parametrach sprężystych, uzyskano analityczne rozwiązanie systemu stochastycznego.
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Efficiency of IEEE 802.15.4a UWB Impulse Radio Spectrum Shaping
PublicationThis paper presents results of impulse radio signal spectrum shaping efficiency investigations. Basic parameters of IEEE 802.15.4a UWB signal and outline of proposed spectrum shaping methods are briefly described. The main part of the paper presents influence of signal and algorithms parameters on the results of spectrum shaping.
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Application of IR UWB Spectrum Shaping to IEEE 802.15.4a Standard
PublicationCoexistence of existing narrowband systems and new ultra wideband devices in the same frequency range requires using some interference mitigation techniques, for example based on spectrum shaping. This paper presents efficiency of impulse radio spectrum shaping methods, applied to IEEE 802.15.4a UWB alternate physical layer signals. Basic parameters of 802.15.4a signal structure and outline of proposed spectrum shaping methods...
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Necessary covariance conditions for a one-field Lax pair
PublicationBadamy kowariancje w odniesieniu do transformacji Darboux wielomianowych różniczkowych i różnicowych operatorów z współczynnikami danymi przez funkcje jednego bazowego pola.
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Direct spectrum detection based on Bayesian approach
PublicationThe paper investigates the Bayesian framework's performance for a direct detection of spectrum parameters from the compressive measurements. The reconstruction signal stage is eliminated in by the Bayesian Compressive Sensing algorithm, which causes that the computational complexity and processing time are extremely reduced. The computational efficiency of the presented procedure is significantly...
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New method of IEEE 802.15.4a UWB Impulse Radio Spectrum Shaping
PublicationThis paper presents a new technique of IEEE 802.15.4a ultra-wideband signal spectrum control, based on changes in sequences of transmitted pulses with very short duration time. Basic parameters of UWB signal and outline of proposed spectrum shaping methods are briefly described. The main part of the paper presents influence of signal and algorithms parameters on the results of spectrum shaping.
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Tonality Estimation and Frequency Tracking of Modulated Tonal Components
PublicationA novel method for tonality estimation and frequency tracking of tonal components modulated in frequency and amplitude is presented. The algorithm detects the local maxima of magnitude spectra corresponding to three contiguous frames of a signal and matches them into the tonal track candidates. The magnitude-based and phase-based methods are used to estimate the frequency jumps between spectrum maxima belonging to the tonal track...
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IEEE 802.15.4a Impulse Radio Spectrum Shaping by Changes in Pulse Sequence
PublicationThis paper presents one of possible techniques of IEEE 802.15.4a ultra-wideband signal spectrum control, based on changes in sequences of transmitted pulses with very short duration time. This technique can reduce probability of mutual interferences between new ultra-wideband and existing narrowband devices, which may be helpful in further studies on allowing UWB transmission in wider range of spectrum in theEuropean Union.
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Analytical studies of spectrum broadcast structures in quantum Brownian motion
PublicationSpectrum broadcast structures are a new and fresh concept in the quantum-to-classical transition, introduced recently in the context of decoherence and the appearance of objective features in quantum mechanics. These are specific quantum state structures, responsible for the objectivization of the decohered state of a system. Recently, they have been demonstrated by means of the well-known quantum Brownian motion model of the recoilless...
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THE SYNCHROSQUEEZING METHOD IN BEARING ESTIMATION OF STATIONARY SIGNALS FOR PASSIVE SONAR WITH TOWED ARRAY
PublicationIn this paper, a novel method of bearing estimation in a passive sonar system with a towed array is introduced. The classical approach of bearing estimation based on the spatial spectrum [1] is extended by using the synchrosqeezing method that is a part of the reassignment method introduced by Kodera et al. [2]. Using this method leads to a precise bearing estimation. The proposed method requires a relatively small amount of computation,...
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Investigation on accelerated impedance spectrum measurement method with multisine signal stimulation
PublicationThe paper presents an investigation on the accelerated impedance spectrum measurement method, oriented at parameter identification of technical objects modelled by a linear equivalent circuit, e.g. anticorrosion coatings.The method is based on multisine signal stimulation of an object and response analysis by triangle window filterbanks.It has several advantages, as compared with conventional point-by-point spectrum measurement....
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Identification of Unstable Reference Points and Estimation of Displacements Using Squared Msplit Estimation
PublicationThe article presents a new version of the method for estimating parameters in a split functional model, which enables the determination of displacements of geodetic network points with constrained datum. The main aim of the study is to present theoretical foundations of Msplit CD estimation and its basic properties and possible applications. Particular attention was paid to the efficacy of the method in the context of geodetic...
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Detection of the Direct Sequence Spread Spectrum Signals with BPSK Modulation
PublicationThis paper presents a method of the DS CDMA signals with BPSK modulation detection through the examination of the enhanced signal spectrum density. On the base of experiments carried out on the real radio communication signals the impact of a narrowband emission occurring in the examined frequency band on the detection process effectiveness was shown. The results of the experiment aimed at the detection of the satellite navigation...
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Ab Initio Study of the Electronic Spectrum of 7-Hydroxyquinoline
PublicationThe electronic spectrum of 7-hydroxyquinoline has been studied by using ab initio Multi-State Multi-Reference Møller-Plesset Second-Order Perturbation Theory (MSMRMP2). The energy range up to 6.5 eV is taken into consideration. The lowest π–π* transition is calculated to have an energy of 3.65 eV in good agreement with experimental data. Several other π–π* transitions are predicted to have excitation energies of 4.93, 5.20, 5.47,...
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Induction Motor Bearings Diagnostic Using MCSA and Normalized Tripple Covariance
PublicationDiagnosis of induction motors, conducted remotely by measuring and analyzing the supply current is attractive with the lack of access to the engine. So far there is no solution, based on analysis of current, the credibility of which allow use in industry. Statistics of IM bearing failures of induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is so important. The article provides...
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MCSA with Normalized Triple Covariance as a bearings diagnostic indicator in an induction motor
PublicationStatistics of bearing failures in induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is very important. Vibration methods for bearing diagnostics have one major disadvantage - they require the availability of the machine for sensors installation. This is the reason for seeking new methods based on motor supply current analysis. Diagnosis of induction motors, conducted remotely...
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The influence of small amount of substances present in tissue on the optical spectrum of immunosuppressive drug
PublicationIn this paper, we describe how commonly present in tissue substances - sodium chloride and glucose - affect the optical spectrum of an immunosuppressive drug (Cyclaid® by Apotex). Prepared samples were investigated using the spectrophotometer in the spectrum range from 250 nm to 1100 nm. The maximum wavelength shift calculated on the basis of measurement results is not bigger than the measurement wavelength step. So, it can be...
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Stress Monitoring System for Individuals with Autism Spectrum Disorders
PublicationIn this article, a stress monitoring system tailored for individuals with Autism Spectrum Disorders (ASD) and developed for the educational institution is presented. People with ASD face problems with effective stress management due to their high self-perceived levels of stress, poor ability to cope with it, and dificulties with the accurate detection of the source of stress. Consistently, being able to measure stress appears to...
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The accuracy of pulse rate estimation from the sequence of face images
PublicationThe goal of this paper is to analyze the accuracy of pulse rate estimation from the sequence of face images. Simulated and real signals were used to evaluate two pulse rate estimators; one for frequency domain and the second one for time domain using the autocorrelation function. The results show that the mean difference between the reference measurements and estimated pulse rate values are about 2bpm. In the analysis of short...
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Behaviometrics of Digital Games for Children with Autism Spectrum Disorder
PublicationTe paper reports current stage of the project Automated Terapy Monitoring for Children with Developmental Disorders of Autism Spectrum (AUTMON), that aims at development of methods and tools to allow for the automatic evaluation of the therapy progress among children with autism. Finding objective measures suitable for evaluating therapy progress would let create a system supporting those who diagnose autism and the therapists...
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Spectrum-based modal parameters identification with Particle Swarm Optimization
PublicationThe paper presents the new method of the natural frequencies and damping identification based on the Artificial Intelligence (AI) Particle Swarm Optimization (PSO) algorithm. The identification is performed in the frequency domain. The algorithm performs two PSO-based steps and introduces some modifications in order to achieve quick convergence and low estimation error of the identified parameters’ values for multi-mode systems....
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Lattice filter based multivariate autoregressive spectral estimation with joint model order and estimation bandwidth adaptation
PublicationThe problem of parametric, autoregressive model based estimation of a time-varying spectral density function of a multivariate nonstationary process is considered. It is shown that estimation results can be considerably improved if identification of the autoregressive model is carried out using the two-sided doubly exponentially weighted lattice algorithm which combines results yielded by two one-sided lattice algorithms running...
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Empirical analyses of robustness of the square Msplit estimation
PublicationThe paper presents Msplit estimation as an alternative to methods in the class of robust M-estimation. The analysis conducted showed that Msplit estimation is highly efficient in the identification of observations encumbered by gross errors, especially those of small or moderate values. The classical methods of robust estimation provide then unsatisfactory results. Msplit estimation also shows high robustness to single gross errors...
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Current based Normalized Triple Covariance as a bearings diagnostic feature in induction motor
PublicationDiagnosis of induction motors, conducted remotely by measuring and analyzing the supply current is attractive with the lack of access to the engine. So far there is no solution, based on analysis of current, the credibility of which allow use in industry. Statistics of IM bearing failures of induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is so important. The article provides...
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Ground-based, Hyperbolic Radiolocation System with Spread Spectrum Signal - AEGIR
PublicationThe most popular radiolocation systems in the world (at present), is the American GPS (Global Positioning System). It is managed by the Department of Defense and there is always the possibility of the occasional inaccuracies or deliberate introduction of errors that prevent its use by the special services or armies of other countries than the U.S.A. This situation has spawned the need to develop an autonomous, ground-based radiolocation...
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Bearing estimation using double frequency reassignment for a linear passive array
PublicationThe paper demonstrates the use of frequency reassignment for bearing estimation. For this task, signals derived from a linear equispaced passive array are used. The presented method makes use of Fourier transformation based spatial spectrum estimation. It is further developed through the application of two-dimensional reassignment, which leads to obtaining highly concentrated energy distributions in the joint frequency-angle domain...
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New results on estimation bandwidth adaptation
PublicationThe problem of identification of a nonstationary autoregressive signal using non-causal estimation schemes is considered. Noncausal estimators can be used in applications that are not time-critical, i.e., do not require real-time processing. A new adaptive estimation bandwidth selection rule based on evaluation of pseudoprediction errors is proposed, allowing one to adjust tracking characteristics of noncausal estimators to unknown...
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The influence of intermolecular correlations on the infrared spectrum of liquid dimethyl sulfoxide
PublicationDimethyl sulfoxide (DMSO) is routinely applied as an excellent, water-miscible solvent and chemical reagent. Some of the most important data concerning its liquid structure were obtained using infrared (IR) spectroscopy. However, the actual extent of intermolecular correlations that connect the isolated monomer spectrum to the IR response of the bulk liquid is poorly studied thus far. Using ab initio molecular dynamics (AIMD) simulations,...
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Theoretical study of the photoelectron spectrum of ethyl formate: Ab initio and density functional theory investigation
PublicationThe first ionization energy and associated photoelectron spectrum of ethyl formate are investigated with quantum chemistry calculations. The geometries, harmonic vibrational frequencies and first ionization energy are computed at the Hartree-Fock (HF) and at the second order Moller-Plesset perturbation theory (MP2). Moreover, accurate ionization energies are obtained with the Coupled-Cluster theory including singles and doubles...
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Estimation of electrode contact in capacitive ECG measurement
PublicationIn the paper a method of electrode’s contact estimation in capacitive electrocardiogram (CECG) is presented. Proposed solution allows estimation of contact quality for each individual electrode. This enables construction of multi-electrode CECG systems, where electrode pairs can be selected on the basis of the individual electrode contact quality.
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Evaluating Accuracy of Respiratory Rate Estimation from Super Resolved Thermal Imagery
PublicationNon-contact estimation of Respiratory Rate (RR) has revolutionized the process of establishing the measurement by surpassing some issues related to attaching sensors to a body, e.g. epidermal stripping, skin disruption and pain. In this study, we perform further experiments with image processing-based RR estimation by using various image enhancement algorithms. Specifically, we employ Super Resolution (SR) Deep Learning (DL) network...
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The Effect of Varying the Light Spectrum of a Scene on the Localisation of Photogrammetric Features
PublicationIn modern digital photogrammetry, an image is usually registered via a digital matrix with an array of colour filters. From the registration of the image until feature points are detected on the image, the image is subjected to a series of calculations, i.e., demosaicing and conversion to greyscale, among others. These algorithms respond differently to the varying light spectrum of the scene, which consequently results in the feature...
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Isotope shifts in the spectrum of Pb I
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