Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "aliasing" wg kryterium: Temat

  Lista filtrów
Wyrównaj
    Wyświetlanie 1-9 z 9
    Tytuł:
    Influence of the compact explicit filtering method on the perturbations growth in temporal shear-layer flow
    Wpływ jawnej filtracji metodą kompactową na wzrost zaburzeń w nieustalonym przepływie z warstwą ścinającą
    Autorzy:
    Tyliszczak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/281098.pdf
    Data publikacji:
    2003
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    compact scheme
    filtering
    aliasing removal
    Opis:
    In this paper the effect of the explicit filtering of high frequency phenomena performed by means of the high order compact filters is presented. A 2D unsteady incompressible flow in which the perturbations super-imposed on the mean velocity profile evolve in time is considered. The dependence of the amplitudes of disturbances is analysed for various filtering procedures and compared with other methods intended to remove high frequency waves.
    W pracy przedstawiono efektywność jawnej filtracji zjawisk wysokoczęstotliwościowych przy zastosowaniu filtracji kompaktowej. Analizie poddano nieściśliwy dwuwymiarowy przepływ z warstwą ścinającą w którym rozpatrywano ewolucję zaburzeń nałożonych na pole prędkości średniej. Przedstawiono porównania wartości amplitud zaburzeń obliczonych przy zastosowaniu różnych procedur filtracji oraz dla innych metod stosowanych do eliminowania zjawisk wysokoczęstotliwościowych.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2003, 41, 1; 19-32
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Artifacts related to cone beam computed tomography technology (CBCT) and their significance for clinicians: illustrated review of medical literature.
    Autorzy:
    Olszewski, Raphael
    Powiązania:
    https://bibliotekanauki.pl/articles/2129258.pdf
    Data publikacji:
    2020-04-03
    Wydawca:
    Presses Universitaires de Louvain
    Tematy:
    CBCT
    artefact
    aliasing artéfact
    ring artéfact
    beam hardening artéfact
    artéfact métal
    artifact
    aliasing artifact
    ring artifact
    beam hardening artifact
    metallic artifact
    Opis:
    Objective: to explain the meaning and to illustrate technical artifacts (aliasing as well as the ring artifact) and beam hardening (metal artifact) that can be present in the dentomaxillofacial cone beam computed tomography (CBCT), and to check the accessibility of free illustrations of these artifacts in medical publications. Material and methods: One observer applied five search equations using database PubMed. The exclusion criteria were: experimental studies, animal studies, studies not related to dentomaxillofacial area, and articles with closed access. There was no time limit for the search of articles. We limited our search to English and French language. Results: Only 3 articles out of 434 publications were retained after application of inclusion/exclusion criteria. In these articles only 4 annotated figures were freely accessible in medical publications from PubMed. In this paper we presented examples of aliasing, ring artifact, and beam artifacts from I-CAT, Carestream 9000 3D (Kodak), and Planmeca Promax 3D Mid CBCT. The intensity of beam hardening artifact varies from major degradation of image (i.e., subperiosteal implants, bridges, crowns, dental implants, and orthodontic fix appliances), through mean degradation (screws securing titanium mesh, head of mini-implant) to no beam hardening on metallic devices (orthodontic anchorage, orthodontic contention wire) or on dense objects (endodontic treatments, impression materials, Lego box). Some beam hardening artifacts arising from nasal piercing, hairs, or hearing aid device may be present on the image but they will not disturb the evaluation of the field of view. Conclusions: reduction of aliasing artifact is related with the improvement of detectors quality. The presence of ring artifact means that CBCT device has lost its calibration. The field of view (FOV) needs to be reduce in order to avoid scanning regions susceptible to beam hardening (e.g., metallic restorations, dental implants). Finally, the accessibility to open knowledge on technique -related CBCT artifacts seems extremely limited when searching at PubMed database.
    Źródło:
    Nemesis. Negative Effects in Medical Sciences Oral and Maxillofacial Surgery; 2020, 11, 1; 1-29
    2593-3604
    Pojawia się w:
    Nemesis. Negative Effects in Medical Sciences Oral and Maxillofacial Surgery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Two relations for generalized discrete Fourier transform coefficients
    Autorzy:
    Spałek, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/201835.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    generalized discrete Fourier transform
    coefficient errors
    aliasing
    dyskretna transformata Fouriera
    Opis:
    A new generalized discrete Fourier transform DFT that allows for sample shift δ 2 [0, T/N] in time-domain is defined. Two relations are proved for the sum of errors between generalized DFT coefficients and theirs theoretical values. The first is the equation for samples received for continuous and piecewise–smooth functions. The second relation is the inequality for samples generated by discontinuous functions. Moreover, the influence of samples shift on generalized DFT coefficients values, which leads to aliasing phenomenon, is presented.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 3; 275-281
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectrum Aliasing Does Occur Only in Case of Non-ideal Signal Sampling
    Autorzy:
    Borys, Andrzej Marek
    Powiązania:
    https://bibliotekanauki.pl/articles/1844609.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    signal sampling
    occurrence of spectrum aliasing and folding
    signal modelling
    non ideal signal sampling operation
    Opis:
    In this paper, it has been shown that the spectrum aliasing and folding effects occur only in the case of non-ideal signal sampling. When the duration of the signal sampling is equal to zero, these effects do not occur at all. In other words, the absolutely necessary condition for their occurrence is just a nonzero value of this time. Periodicity of the sampling process plays a secondary role.
    Źródło:
    International Journal of Electronics and Telecommunications; 2021, 67, 1; 79-85
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectrum Aliasing Does not Occur in Case of Ideal Signal Sampling
    Autorzy:
    Borys, Andrzej Marek
    Powiązania:
    https://bibliotekanauki.pl/articles/1844614.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    signal sampling
    occurrence of spectrum aliasing and folding
    signal modelling
    signal sampling operation
    Kronecker time function
    Kronecker comb
    Opis:
    A new model of ideal signal sampling operation is developed in this paper. This model does not use the Dirac comb in an analytical description of sampled signals in the continuous time domain. Instead, it utilizes functions of a continuous time variable, which are introduced in this paper: a basic Kronecker time function and a Kronecker comb (that exploits the first of them). But, a basic principle behind this model remains the same; that is it also a multiplier which multiplies a signal of a continuous time by a comb. Using a concept of a signal object (or utilizing equivalent arguments) presented elsewhere, it has been possible to find a correct expression describing the spectrum of a sampled signal so modelled. Moreover, the analysis of this expression showed that aliases and folding effects cannot occur in the sampled signal spectrum, provided that the signal sampling is performed ideally.
    Źródło:
    International Journal of Electronics and Telecommunications; 2021, 67, 1; 71-77
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Another Proof of Ambiguity of the Formula Describing Aliasing and Folding Effects in Spectrum of Sampled Signal
    Autorzy:
    Borys, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/2055252.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    signal sampling
    occurrence of spectrum aliasing and folding
    modelling of non-ideal signal sampling operation
    Vetterli's model
    Opis:
    In this paper, a new proof of ambiguity of the formula describing the aliasing and folding effects in spectra of sampled signals is presented. It uses the model of non-ideal sampling operation published by Vetterli et al. Here, their model is modified and its black-box equivalent form is achieved. It is shown that this modified model delivers the same output sequences but of different spectral properties. Finally, a remark on two possible understandings of the operation of non-ideal sampling is enclosed as well as fundamental errors that are made in perception and description of sampled signals are considered.
    Źródło:
    International Journal of Electronics and Telecommunications; 2022, 68, 1; 115--122
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Simple proof of incorrectness of the formula describing aliasing and folding effects in spectrum of sampled signal in case of Ideal signal sampling
    Autorzy:
    Borys, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2063994.pdf
    Data publikacji:
    2021
    Wydawca:
    Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
    Tematy:
    folding effects
    ideal signal sampling
    incorrectness of the Formula
    aliasing effects
    spectrum of a sampled signal
    signal sampling
    proof of incorrectness
    Opis:
    A simple proof of the incorrectness of the formula, which is used in the literature nowadays, for description of the aliasing and folding effects in the spectrum of a sampled signal in the case of an ideal signal sampling, is given in this paper. By the way, it is also shown that such the effects cannot occur at all, when the signal sampling is considered to be performed perfectly.
    Źródło:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2021, 15, 3; 873--876
    2083-6473
    2083-6481
    Pojawia się w:
    TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Problem of Aliasing and Folding Effects in Spectrum of Sampled Signals in View of Information Theory
    Autorzy:
    Borys, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/2055264.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    signal sampling
    modeling of sampled signal in the time domain
    signal information content
    spectrum aliasing and folding
    Banach–Tarski-like paradox in signal sampling
    Opis:
    In this paper, the problem of aliasing and folding effects in spectrum of sampled signals in view of Information Theory is discussed. To this end, the information content of deterministic continuous time signals, which are continuous functions, is formulated first. Then, this notion is extended to the sampled versions of these signals. In connection with it, new signal objects that are partly functions but partly not are introduced. It is shown that they allow to interpret correctly what the Whittaker–Shannon reconstruction formula in fact does. With help of this tool, the spectrum of the sampled signal is correctly calculated. The result achieved demonstrates that no aliasing and folding effects occur in the latter. Finally, it is shown that a Banach–Tarski-like paradox can be observed on the occasion of signal sampling.
    Źródło:
    International Journal of Electronics and Telecommunications; 2022, 68, 2; 315--322
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The steady-state impedance operator of a linear periodically time-varying one-port network and its determination
    Autorzy:
    Kłosiński, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/930020.pdf
    Data publikacji:
    2009
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    układ liniowy
    parametr okresowo zmienny
    operator cykloparametryczny
    identyfikacja
    impedancja okresowo zmienna
    okresowy stan ustalony
    generowanie harmonicznych
    periodically time-varying impedance
    periodic steady state
    linear periodically time-varying system
    circular parametric operator
    harmonics aliasing
    identification
    Opis:
    The main subject of the paper is the description and determination of the impedance operator of a linear periodically time-varying (LPTV) one-port network in the steady-state. If the one-port network parameters and the supply vary periodically with the same period, the network reaches a periodic steady state. However, the sinusoidal supply may induce a nonsinusoidal voltage or current. It is impossible to describe such a phenomenon by means of one complex number. A periodically time-varying one-port network working in a steady-state regime can be described with a circular parametric operator. Within the domain of discrete time, such an operator takes the form of a matrix with real-valued entries. The circular parametric operator can be transformed into the frequency domain using a two-dimensional DFT. This description makes it possible to quantitatively assess LPTV system input and output harmonics aliasing. The paper also presents the derivation and the proof of convergence of an iteration scheme for the identification of circular parametric operators. The scheme may be used to determine the impedance of an LPTV one-port network. Some results of computer simulations are shown.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2009, 19, 4; 661-673
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

      Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies