1,720,955 research outputs found
Acoustic-seismic coupling of broadband signals – support for on-site inspections under the Comprehensive Nuclear Test-Ban-Treaty
Full text linkIn this PhD thesis the process of acoustic-seismic coupling and a method to reduce acoustically induced soil vibrations by applying an acoustic shielding to seismic sensors are investigated.
The research is motivated by the verification of the Comprehensive Nuclear-Test-Ban Treaty: During on-site inspections sensitive seismic measurements can be performed to record seismic aftershocks created in the aftermath of a large, underground, human-caused explosion. This aims to precisely localise the hypocentre of that explosion to verify whether its origin was a nuclear or chemical one. However, these seismic measurements can be disturbed by other seismic signals in the inspection area and thus weak aftershock signals might go undetected. In this work disturbances caused by airborne sources are analysed: When sound waves hit the ground they excite soil vibrations which can mask weak aftershock signals. The findings of this work can be used in the development of new guidelines to improve the sensitivity of seismic on-site inspection measurements.
For this measurements of sound pressure and the acoustically excited soil velocity, recorded with geophones places at the soil surface and in burying depths of up to 0.6 m, in flat terrain with sandy soil, are presented. The acoustic excitation was realised by broadband sound of jet-aircraft overflights, covering a broad range of incidence angles and due to the large distance arriving as plane waves, and of noise artificially produced by a speaker. By evaluating a multitude of overflight events it is shown that the acoustic-seismic coupling coefficient (i.e. the spectral ratio between soil velocity and sound pressure) only depends on the angle of incidence of the acoustic wave and the frequency. Thus, angle-dependent averaging of the coupling coefficient, obtained from the signals of several overflight events, can be performed which significantly improves the signal-to-noise ratio. While previous publications presented only pointwise measurements in this work results for a wide range of angles of incidence and frequencies are presented.
In seismic spectra signal frequency bands of increased and decreased soil velocity are observed. These are caused by interfering seismic waves: The directly acoustically excited wave and waves which have been acoustically excited in a certain horizontal distance and which have been reflected within the ground before reaching the sensor.
The seismic response to the broadband acoustic excitation with a range of incidence angles is used to obtain near-surface soil properties e.g. the P-wave velocity and the depth of the reflecting boundary. For this three theoretical models are introduced taking into account contributions of different numbers and types of the interfering waves. While sensors placed at the surface generally lead to the most reliable results, buried sensors are used to verify the models.
Additionally, during several measurements an acoustic shielding is placed over some sensors. Thus, the sound pressure of the incident acoustic waves is reduced significantly. From the soil velocity recorded with the shielded geophones and the reflection characteristics the horizontal propagation range of acoustically induced seismic signals is estimated. It is shown that treating the process of acoustic-seismic coupling as a local effect is an insufficient approach.
Finally, first suggestions for acoustic shieldings to reduce disturbing signals during sensitive seismic measurements are presented and the applicability during on-site inspections is discussed. An outlook for further research is given: Design and material of a suitable acoustic shielding should be investigated to fulfil requirements of high acoustic damping properties for signals of frequencies of a few Hz
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
- …
