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Μοντελοποίηση υπόγειου υδροφορέα υπό κλίση
No full textΣτην παρούσα εργασία αναλύεται η ροή σε υπόγειο υδροφορέα υπό κλίση, ο οποίος εμπλουτίζεται μέσω κατακόρυφης τροφοδοσίας και δημιουργείται και προτείνεται ένα μαθηματικό μοντέλο για τον υπολογισμό της συνολικής εκροής το κατάντη άκρο του. Στην περίπτωση ανατροφοδότησης, το διεισδύον νερό ακολουθεί κάθετη ροή, η οποία καλείται ακόρεστη ροή, έως ότου επέλθει στον υπόγειο υδροφορέα κορεσμένη ροή με το νερό να κινείται παράλληλα με τον υπόγειο υδροφορέα. Ο Boussinesq χρησιμοποίησε την υδραυλική θεωρία των Dupuit-Forchheimer για να εκφράσει την κορεσμένη ροή των υπογείων υδάτων μέσω ενός πορώδους στρώματος, μέσω μιας μη γραμμικής εξίσωσης για τη υφιστάμενη ροή, η οποία καθορίζεται από τη γραμμική επίδραση της βαρύτητας και την τετραγωνική επίδραση της πίεσης. Χρησιμοποιώντας τη διαφορική εξίσωση της διατήρησης της μάζας, ο Boussinesq κατέληξε σε μία μη γραμμική, δεύτερης τάξης, διαφορική εξίσωση που εκφράζει την εξέλιξη των βαθών της στήλης του νερού εντός του υπόγειου υδροφορέα. Μέχρι στιγμής, ωστόσο, μόνο ορισμένες ειδικές λύσεις είναι γνωστές όσον αφορά στο συγκεκριμένο πρόβλημα.
Η μη γραμμικότητα της εξίσωσης Boussinesq αποτελεί το σημαντικότερο εμπόδιο στην αναλυτική λύση της εξέλιξης των προφίλ του νερού και κατ’ επέκταση του υπολογισμού της απορροής σε υπόγειο υδροφορέα υπό κλίση, ο οποίος επαναφορτίζεται. Οι Henderson and Wooding (1964) ανέπτυξαν μια ακριβή, αναλυτική λύση για τη μόνιμη σταθερή κορεσμένη ροή στο παραπάνω πρόβλημα (υπό σταθερό ρυθμό επαναφόρτισης), και το έργο τους αξίζει ιδιαίτερη μνεία στην ιστορία των λύσεων της μη γραμμικής εξίσωσης του Boussinesq. Ωστόσο, η απουσία μιας γενικής λύσης για την μεταβατική δυναμική κατάσταση, η οποία έχει κύριο πρακτικό ενδιαφέρον για το τομέα της Υδρολογίας οδήγησε στην ανάπτυξη προσεγγιστικών λύσεων της μη γραμμικής εξίσωσης του Boussinesq.
Στην παρούσα εργασία, προσεγγίζεται η εξίσωση της αποθηκευτικότας ενός υπόγειου υδροφορέα, με ολοκλήρωση της ακριβούς, αναλυτικής λύση των κατατομών του βάθους της μη γραμμικής εξίσωσης του Boussinesq σε κατάσταση μόνιμης ροής (steady state). Η εξίσωση αυτή αποτελείται από ένα γραμμικό και ένα μη γραμμικό όρο που επηρεάζουν την απορροή. Σε αντίθεση με παλαιότερες μελέτες, εδώ χρησιμοποιήθηκαν οι ακριβείς λύσεις για την αποθηκευτικότητα του υδροφορέα σε συνθήκες μόνιμης ροής διατηρώντας τη μη γραμμικότητα χωρίς οποιαδήποτε γραμμική ή άλλη εμπειρική προσέγγιση. Οι μαθηματικές μορφές που εξάγονται οδηγούν αβίαστα στη θεωρητική στοιχειοθέτηση παραδοσιακά χρησιμοποιούμενων εμπειρικών σχέσεων, χωρίς την ανάγκη της εισαγωγής εμπειρικών παραμέτρων. Επιπλέον υποδεικνύουν με σαφήνεια τα όρια ισχύος των παλαιότερων προσεγγίσεων, ως προς την εφαρμογή τους στα πλαίσια της προσέγγισης οιωνοί μονίμων συνθηκών. Τέλος σε μία προσπάθεια διεύρυνσης των δυνατοτήτων εφαρμογής της υδραυλικής θεωρίας που αναπτύχθηκε προς μία περισσότερο εμπειρική υδρολογική κατεύθυνση, προτείνεται ένα νέο υβριδικό μοντέλο περιγραφής της απόκρισης της απορροής
iv
σε δυναμικά εξελισσόμενες συνθήκες ροής, και με μεταβλητή φόρτιση. Το συγκεκριμένο μοντέλο εφαρμόζεται και ελέγχεται σε ιστορικές πειραματικές μετρήσεις με ιδιαίτερη επιτυχία και αναμένεται να αποδειχθεί χρήσιμο στην παραμετροποίηση και ερμηνεία πραγματικών υδρογραφημάτωνHillslope processes involving flow through an inclined shallow aquifer range from subsurface stormflow to stream base flow (drought flow, or groundwater recession flow). In the case of recharge, the infiltrating water moves vertically as unsaturated flow until it reaches the saturated groundwater, where the flow is approximately parallel to the base of the aquifer. Boussinesq (1901) used the Dupuit-Forchheimer (D-F) hydraulic theory to formulate unconfined groundwater flow through a soil layer resting on an impervious inclined bed, deriving a nonlinear equation for the flow rate that consists of a linear gravity-driven component and a quadratic pressure-gradient component. Inserting that flow rate equation into the differential storage balance equation (volume conservation) Boussinesq obtained a nonlinear second-order partial differential equation for the depth. So far however, only few special solutions have been advanced for that governing equation.
The nonlinearity of the equation of Boussinesq is the major obstacle to deriving a general analytical solution for the depth profile of unconfined flow on a sloping base with recharge (from which the discharges could be then determined). Henderson and Wooding (1964) were able to obtain an exact analytical solution for steady unconfined flow on a sloping base, with recharge, and their work deserves special note in the realm of solutions of the nonlinear equation of Boussinesq. However, the absence of a general solution for the transient case, which is of practical interest to hydrologists, has been the motivation for developing approximate solutions of the non-linear equation of Boussinesq.
In this work, we derive the aquifer storage function by integrating analytically over the aquifer base the depth profiles resulting from the complete nonlinear Boussinesq equation for steady flow. This storage function consists of a linear and a nonlinear outflow-dependent term. Then, we use this physics-based storage function in the transient storage balance over the hillslope, obtaining analytical solutions of the outflow and the storage, for recharge and drainage, via a quasi-steady flow calculation. The hydraulically derived storage model is thus embedded in a quasi-steady approximation of transient unconfined flow in sloping aquifers. We generalise this hydrologic model of groundwater flow by modifying the storage function to be the weighted sum of the linear and the nonlinear storage terms, determining the weighting factor objectively from a known integral quantity of the flow (either an initial volume of water stored in the aquifer or a drained water volume). We demonstrate the validity of this model through comparisons with experimental data and simulation results.Complete
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
Appropriate 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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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