1,720,961 research outputs found
A bedform tracking tool coupled with Fast Fourier Transform decomposition
No full textThis bedform tracking tool identifies bedforms based on the sign change of the gradient of streambed profiles, dz/dx. Before fed to the bedform tracking algorithm, bed elevation profiles (BEPs) are filtered using Fast Fourier Transform (FFT) decomposition to extract large bedforms buried underneath superimposed secondary bedform features. Thereafter, characteristics (morphology and kinematics) of individual bedforms are quantified. Please refer README for more details.Quantifying bedform characteristics is crucial because bedforms are omnipresent and play an important role in fluvial environments. Bedforms induce form drag against flows and can significantly alter water depth, flow velocity, and sediment transport rate (i.e. the hydraulic roughness of channels can be parameterized with bedforms). In addition, ship navigation can be constrained by the presence and distributions of bedform crests; and localized scour within bedform troughs can deteriorate performance of fluvial infrastructures (e.g. containment walls, embedded pipes, or groynes). Despite of its importance, characterizing bedforms has been challenges due to inherent multi-scale features observed in channel bathymetries in both natural rivers and laboratory flumes. To tackle such challenges, we developed a bedform tracking tool coupled with Fast Fourier Transform (FFT) decomposition. A key advantage of the presented bedform tracking method is that bedform characteristics (morphology and kinematics) can be quantified in a wider range of scales.National Science Foundation (NSF) Career Grant Geophysical Flow Control (Grant No. 1351303)Lee, Jiyong; Musa, Mirko; Guala, Michele. (2021). A bedform tracking tool coupled with Fast Fourier Transform decomposition. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/e1fe-sb56
Scaled Hydrokinetic Turbine Array installed in a laboratory channel and flood-like sediment transport conditions: topography, flow velocity and array model performance
No full textPlease see Readme files included in every data folder.The data represent sediment flux, spatio-temporally resolved topographic scans, flow velocity and voltage from the hydrokinetic turbine array experiments presented in the referenced scientific article published on Nature Energy (see reference). Hydrokinetic Energy represents a viable source of renewable energy that harness the kinetic energy of natural currents. Our experiments show that this technology can be deployed efficiently in large sandy rivers (e.g. Mississippi River), without compromising the geomorphic equilibrium of the stream and the structural safety of the turbine foundation, even in the presence of large migrating dunes.National Science Foundation CAREER: Geophysical Flow Control (award ID 13513013)Institute on the Environment (IonE), University of MinnesotaMusa, Mirko; Hill, Craig; Sotiropoulos, Fotis; Guala, Michele. (2019). Scaled Hydrokinetic Turbine Array installed in a laboratory channel and flood-like sediment transport conditions: topography, flow velocity and array model performance. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/353t-xm19
Hydrokinetic turbine array performance and geomorphic effects under different siting strategies and sediment transport conditions: topography, flow velocity and array performance measurements
No full textPlease see Readme files included in each data folder.Hydrokinetic energy can be extracted efficiently from naturally occurring water flows. Although representing a continuous and ubiquitous source of kinetic energy, rivers in particular are delicate environments, sensitive to external disturbances. Asymmetric installation of in-stream hydrokinetic energy converters have proven to actively interact with sediment transport and bedforms characteristics, triggering non-local geomorphic effects that resemble river instabilities known as forced-bars. This data-set comprises a series of measurements of channel topography evolution, flow velocity around the turbines and array performance under different configurations.National Science Foundation CAREER: Geophysical Flow Control (award ID 13513013)CEGE Department fellowship awarded to PhD student M. MusaMusa, Mirko; Hill, Craig; Guala, Michele. (2019). Hydrokinetic turbine array performance and geomorphic effects under different siting strategies and sediment transport conditions: topography, flow velocity and array performance measurements. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/4p2e-p886
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
Measurements of spatio-temporal fluvial channel bed evolution in an array of yawed porous vanes at the Saint Anthony Falls Laboratory (SAFL) main channel
No full textSupplementary data for associated manuscript. Please see README.txt included in the data archive for more details.Controlling lateral sediment flux and bed surface elevation distributions is important engineering solutions for sustainable river management. However, quantification of the lateral sediment flux has posed great challenges for river engineers for decades due to difficulties in measuring high resolution 2D spatio-temporal bed surface evolution data, \eta(x,y,t), when lateral sediment flux control is imposed by hydraulic structures. Here, \eta is bed surface elevation. Dimensions x and y are stream- and span-wise directions, and t is time. We conducted two sets of open channel experiments, in which \eta(x,y,t) was monitored using the state-of-the-art laser scanning data acquisition system. The first experiment was carried out without hydraulic structures, namely baseline case. The second experiment was conducted under the same hydraulic condition with an array of yawed porous vanes that were installed at the one-half of the channel width, imposing asymmetric lateral sediment flux. By comparing results from these two sets of experiments, the effects of an array of yawed porous vanes on the lateral sediment flux were quantified. We found that an array of porous yawed vanes can effectively direct sediment flux in the lateral direction by 9-18% of the averaged streamwise sediment flux under the current array configurations and hydraulic conditions.Water Power Technologies Office (DE-EE0008947)Lee, Jiyong; Tseng, Chien-Yung; Musa, Mirko; Guala, Michele. (2024). Measurements of spatio-temporal fluvial channel bed evolution in an array of yawed porous vanes at the Saint Anthony Falls Laboratory (SAFL) main channel. Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/zhqp-tt29
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
- …
