1,720,977 research outputs found
Design of a scroll vortex inlet for supercritical approach flow
No full textVortex drop shafts are used in urban drainage systems to connect two sewers located at considerably different elevations. After their introduction in 1947, these were studied with particular reference to subcritical approach flow. Vortex shafts for supercritical approach flow can also be used, but the intake structure may have relatively high cost due to the complex geometry. The present study includes experimental results of a specific investigation on the changes to be made in the supercritical approach channel, if a subcritical vortex intake is used. The experimental investigation analyses the effect of a hydraulic jump on the performance of vortex intake structure to define appropriate technical solutions, essentially consisting in a negative step to be located along the supercritical approach channel. Design criteria are finally presented for the evaluation of the step height and its distance from the vortex intake structure
Measurement and estimation of seismic attenuation for near-surface site characterization
Full text linkSeismic attenuation is a fundamental parameter on the comprehension of the viscoelastic real behavior of the medium. Characterization of the ability of materials to transmit and dissipate seismic waves is even important for petrophysical descriptions of reservoir rocks. The purpose of this work is to investigate the reliability of the rise-time and the spectral ratio methods for estimation in a seismic downhole campaign, to obtain accurate profiles. In this study, we applied two different methods to estimate attenuation. We used a standard spectral ratio technique to obtain the frequency independent and then compared the results to obtained in the time domain from rise-time measurements. Most of the borehole attenuation studies presented in literature are carried out for hydrocarbon exploration. The main contribution of the present work is to apply the two most used attenuation estimation methods to near-surface data. They include two techniques to determine the material damping ratio of the soil based on the downhole (DHT) test, and other two for attenuation and dispersion curves from MASW testing
Vortex dropshafts: history and current applications to the sewer system of Naples (Italy)
No full textThe city of Naples (Italy) is well known for its hilly landscape, along with a peculiar geology characterized by volcanic soils (i.e. tuf and pyroclastic rocks). The development of the sewer system serving the urban area has been strongly constrained by these factors. In particular, several drop structures were realized in order to connect the modern urban drainage system (realized in during the last decades) to the early sewer mains realized at the beginning of the nineteenth century and serving the downtown districts located at the sea level. The purpose of these drop structures is twofold: (i) to convey the storm runoff toward the sea through the existing sewer system located at lower elevations, and (ii) to by-pass insufficient sewer channels. Most of the drop structures were realized according to the ‘vortex drop shaft’ scheme, mainly for drop heights larger than 10 meters, up to 80 meters. The proper operation of these structures is crucial to prevent flooding and guarantee the urban safety. The paper aims to describe the most crucial aspects of the hydraulic behavior of the vortex shafts along with some examples of malfunction of these structures. Laboratory experiments were conducted to test existing vortex dropshafts and improve their hydraulic capacity; some relevant results are finally presented, along with pertinent practical issues
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
- …
