1,720,958 research outputs found
Development of tomographic geophysical techniques for the study of geotechnical and environmental problems
No full textThis study investigates an application on electrical resistivity tomography, employing a special electrode array. In this array, one electrode row is placed on the surface and another one is probed into the earth. This array is labeled as ‘surface-to-tunnel’ which has two rows of electrodes running parallel while the ‘interior’ row is placed inside a tunnel.This new array can ‘see’ the area in between the electrodes better in comparison to traditional surface arrays due to increased resolving ability. For data acquisition, new protocols are created. These are based on existing protocols which are dedicated to cross-borehole measurements. New protocols are also optimized by reducing the initial amount of data via Jacobian matrix or Resolution matrix criterion. Finally, these protocols are evaluated for their accuracy.This new array is further studied in order to find the best ratio between the inner probe distance and the vertical distance between arrays. Furthermore, the error which is introduced due to electrode horizontal displacement is calculated regarding to the protocol.As mentioned before, the ‘interior’ array of electrodes can be placed inside a tunnel. But, the tunnel itself is a source of noise so that it can ‘pollute’ the data with extra noise. In this study, the noise is calculated with respect to tunnel volume, electrode positioning, and the current protocol. Some correction methods for tunnel effect are proposed. Data is obtained by synthetic simulation data, and processed with an existing software which was updated for this specific purpose. Apart from the simulated data, measurements are also acquired in a special tank where a handmade apparatus gave the opportunity for a fully controlled experimental environment. Existing knowledge from a ‘surface-to-tunnel’ array is employed at an archaeological site where an already available tunnel is used in order to introduce the ‘interior’ electrode array. The results from real data are compared with theoretical models.Η παρούσα διδακτορική διατρίβη διαπραγματεύεται την εφαρμογή ηλεκτρικών μεθόδων διασκόπησης με τη χρήση μίας ιδιαίτερης διάταξης ηλεκτροδίων, όπου μία σειρά ηλεκτροδίων τοποθετείται στην επιφάνεια του εδάφους και μία ακόμα σειρά ηλεκτροδίων τοποθετείται στο εσωτερικό της γης. O τύπος αυτός μετρήσεων ονομάζεται ‘επιφάνειας-σήραγγας’ με τις δύο σειρές ηλεκτροδίων να είναι μεταξύ τους παράλληλες και την εσωτερική να τοποθετείται μέσα σε σήραγγα.Πρόκειται για μία νέα διάταξη η οποία λόγω αυξημένης ευαισθησίας είναι σε θέση να ‘φωτογραφίσει’ καλύτερα την μεταξύ των ηλεκτροδίων περιοχή σε σχέση με τις παραδοσιακές επιφανειακές μετρήσεις. Για τη λήψη των μετρήσεων δημιουργήθηκαν καινούρια πρωτόκολλα τα οποία βασίσθηκαν στις μετρήσεις μεταξύ κατακόρυφων γεωτρήσεων και αξιολογήθηκαν ώστε να αναδειχθεί το καλύτερο δυνατό ανά περίπτωση. Επιπλέον, τα πρωτόκολλα αυτά βελτιστοποιήθηκαν μειώνοντας τον αρχικό αριθμό μετρήσεων με κριτήριο τον Ιακωβιανό πίνακα ή τον πίνακα ευκρίνειας.Η νέα αυτή διάταξη μελετήθηκε ώστε να βρεθεί η μέγιστη δυνατή απόσταση μεταξύ των εσωτερικών και των επιφανειακών ηλεκτροδίων. Επιπρόσθετα, υπολογίσθηκε το σφάλμα που προκύπτει από την αναντιστοιχία της θέσης των ηλεκτροδίων λόγω οριζόντιας απόκλισης των δύο σειρών.Όπως αναφέρθηκε, η ‘εσωτερική’ σειρά των ηλεκτροδίων μπορεί να τοποθετηθεί μέσα σε σήραγγα. Ωστόσο, η παρουσία της σήραγγας της ίδιας είναι σε θέση να ‘μολύνει’ τις μετρήσεις με επιπρόσθετο θόρυβο. Ο θόρυβος αυτός υπολογίζεται ανάλογα με τις διαστάσεις της σήραγγας, την θέση των ηλεκτροδίων αλλά και με το πρωτόκολλο που χρησιμοποιείται και αντίστοιχα προτείνονται τρόποι διόρθωσης.Τα δεδομένα προέκυψαν από τη δημιουργία συνθετικών μοντέλων προσομοίωσης, τα οποία μελετήθηκαν με την βοήθεια λογισμικού που αναπτύχθηκε για το σκοπό αυτό. Εκτός από τα συνθετικά δεδομένα, μετρήσεις πραγματοποιήθηκαν σε ειδική δεξαμενή στην οποία προσαρμόσθηκε ιδιοκατασκευή παρέχοντας την δυνατότητα πραγματοποίησης μετρήσεων σε πλήρως ελεγχόμενο περιβάλλον.Η γνώση που αποκομίσθηκε από την θεωρητική μελέτη των μετρήσεων ‘επιφάνειας-σήραγγας’ εφαρμόσθηκε σε αρχαιολογικό χώρο με την τοποθέτηση των εσωτερικών ηλεκτροδίων σε σήραγγα. Τα αποτελέσματα αναλύθηκαν και συγκρίθηκαν με τα αποτελέσματα των θεωρητικών μοντέλων
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Optimization of electrical resistivity tomography protocols for detecting archaeological structures in a shallow water marine environment
No full textAppropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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