Wyniki wyszukiwania - Biblioteka Nauki

1

Aligning Projection Images from Binary Volumes

100%

Bleichrodt F. , de Beenhouwer J. , Sijbers J. , Batenburg K. J.

Fundamenta Informaticae

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2014

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tom Vol. 135, nr 1/2

21--42

EN

In tomography, slight differences between the geometry of the scanner hardware and the geometric model used in the reconstruction lead to alignment artifacts. To exploit high-resolution detectors used in many applications of tomography, alignment of the projection data is essential. Markerless alignment algorithms are the preferred choice over alignment with markers, in case a fully automatic tomography pipeline is required. Moreover, marker based alignment is often not feasible or even possible. At the same time, markerless alignment methods often fail in scenarios where only a small number of projections are available. In this case, the angular separation between projection images is large and therefore the correlation between them is low. This is a property that most markerless algorithms rely on. The intermediate reconstruction problem of alignment by projection matching is highly underdetermined in the limited data case. Therefore, we propose a projection matching method that incorporates prior knowledge of the ground truth. We focus on reconstructing binary volumes. A discrete tomography algorithm is employed to generate intermediate reconstructions. This type of reconstruction algorithm does not rely heavily on correlated projection images. Our numerical results suggest that alignment using discrete tomography projection matching produces much better results in the limited angle case, when compared to a projection matching method that employs an algebraic reconstruction method.

2

Using BBC Learning English Podcasts to develop university students' listening skills

75%

Davydenko O.

e-mentor

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2021

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nr 5 (92)

26-35

EN

The emergence of podcasts in an English foreign language (EFL) setting is seen as a helpful aid to foreign language learning. Using podcasts might help improve language learning efficiency. This research addresses how podcasts can be an alternative means of improving English listening comprehension for university students. The study was carried out at Nizhyn Gogol State University, Ukraine, using quantitative and qualitative methods of analyzing data. To collect the data, research tools such as a questionnaire, initial and final testing, and observation were used. The procedure was introduced for a group of first-year students and implemented for six weeks. Special BBC Learning English podcast activities were designed and offered to the students. The main stages have been specified in the process of developing students’ listening skills. In the pre-listening stage, students do preparation activities to prepare for the podcast using their background knowledge. The while-listening stage is aimed at listening for gist, listening for details, making inferences, and summarizing. In the post-listening stage, the listeners are taken beyond the podcast content and set tasks which contribute to integrating other language skills. Samples of activities which correspond to these three stages are provided. A balanced approach to choosing top-down or bottom-up processing within the stages improves the process of forming competencies in listening of first-year students. Hence, based on the positive results of this study, BBC Learning English podcasts with meaningful, appropriate, and interesting activities attract the students’ attention, increase their motivation, and improve their listening comprehension.

3

Estymacja wartości parametrów sygnału na podstawie dostępnej wiedzy

63%

Smołalski G.

Pomiary Automatyka Kontrola

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2014

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tom R. 60, nr 12

1140--1143

PL

Jako menzurand przyjęto jeden z możliwych parametrów segmentu sygnału. Przedstawiono metodę jednolitego uwzględniania wszelkich dostępnych informacji o sygnale. Wykorzystano reprezentację sygnału w skończenie-wymiarowej przestrzeni liczbowej. Rozważono przypadek ogólny, gdy parametr mierzony nie jest równy parametrowi estymowanemu. Przeanalizowano użyteczność danej informacji o sygnale w estymacji określonego jego parametru. Przedstawiono przykład ilustrujący stosowanie zaproponowanej metody.

EN

In this paper a measurand is assumed to be some particular parameter of the signal segment - the estimated parameter E (Section 2). A model of measurement is formulated in which all the information items available about the investigated signal (both those available a priori and those provided by measurement) are uniformly taken into account during the evaluation of the uncertainty of E. All information items are assumed to be certain. It is shown (Section 3) that the investigated signal segment can be interpreted as a point in a finite-dimensional numerical space. With each available information item corresponds in that space a specific constraint (1) of possible signals. Finding out the global extremes of the estimated parameter over the resulting set of possible signals, gives the prior uncertainty interval (3) according to E (Section 4). Measurement of some additional parameter M continues restricting the prior set of possible signals. The uncertainty (4), remaining after the measurement of M, results from a structural discrepancy between parameters E and M. One of measurability necessary conditions is presented in Section 6. It enables an easy rejection of such measured parameters M that cannot be useful for the estimation of E. Finally, an illustrative example for the method has been provided in Section 7.