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Applying a Comprehensive Model for Single-Ring Infiltration: Assessment of Temporal Changes in Saturated Hydraulic Conductivity and Physical Soil Properties
Full text linkModeling agricultural systems, from the point of view of saving and optimizing water,
is a challenging task, because it may require multiple soil physical and hydraulic measurements to
investigate the entire crop cycle. The Beerkan method was proposed as a quick and easy approach to
estimate the saturated soil hydraulic conductivity, Ks. In this study, a new complete three-dimensional
model for Beerkan experiments recently proposed was used. It consists of thirteen different calculation
approaches that differ in estimating the macroscopic capillary length, initial (θi) and saturated (θs)
soil water contents, use transient or steady-state infiltration data, and different fitting methods to
transient data. A steady-state version of the simplified method based on a Beerkan infiltration run
(SSBI) was used as the benchmark. Measurements were carried out on five sampling dates during
a single growing season (from November to June) in a long-term experiment in which two soil
management systems were compared, i.e., minimum tillage (MT) and no tillage (NT). The objectives
of this work were (i) to test the proposed new model and calculation approaches under real field
conditions, (ii) investigate the impact of MT and NT on soil properties, and (iii) obtain information
on the seasonal variability of Ks and other main soil physical properties (θi, soil bulk density, ρb, and
water retention curve) under MT and NT. The results showed that the model always overestimated Ks
compared to SSBI. Indeed, the estimated Ks differed by a factor of 11 when the most data demanding
(A1) approach was considered by a factor of 4–8, depending on the transient or steady-state phase
use, when A3 was considered and by a practically negligible factor of 1.0–1.9 with A4. A relatively
higher seasonal variability was detected for θi at the MT than NT system. Under both MT and NT, ρb
did not change between November and April but increased significantly until the end of the season.
The selected calculation approaches provided substantially coherent information on Ks seasonal
evolution. Regardless of the approach, the results showed a temporal stability of Ks at least from early
April to June under NT; conversely, the MT system was, overall, more affected by temporal changes
with a relative stability at the beginning and middle of the season. These findings suggest that a
common sampling time for determining Ks could be set at early spring. Soil management affected the
soil properties, because the NT system was significantly wetter and more compact than MT on four
out of five dates. However, only NT showed a significantly increasing correlation between Ks and
the modal pore diameter, suggesting the presence of a relatively smaller and better interconnected
pore network in the no-tilled soil. This study confirms the need to test infiltration models under real
field conditions to evaluate their pros and cons. The Beerkan method was effective for intensive soil
sampling and accurate field investigations on the temporal variability of Ks
DETERMINING THE SATURATED HYDRAULIC CONDUCTVITY OF A LOAM SOIL WITH DIFFERENT INFILTROMETER TECHNIQUES
No full textThe saturated soil hydraulic conductivity, Ks, is one of the most important soil
hydraulic properties since it controls many hydrological processes. This hydrodynamic parameter depends on soil texture and structure and it is very difficult to measure. Infiltrometer techniques are becoming very popular to determine Ks in the field but testing alternative approaches is necessary for specific soil types. For a loam soil, the estimated Ks values with six infiltrometer techniques were compared. The so-called BEST procedure of soil hydraulic characterization, the pressure infiltrometer (PI), single head experiments with both the tension infiltrometer (TI) and the mini disk infiltrometer (MDI), the simplified falling head (SFH) technique and the bottomless bucket (BB) method yielded statistically similar estimates of Ks for the sampled area, with mean values differing at the most by a factor of three. The detected differences were attributed to different levels of disturbance of the infiltration surface during the run and to a different duration of the infiltration process. In conclusion, any of the tested infiltration techniques appears usable to obtain the order of
magnitude of Ks at the field site. However, the TI, MDI and SFH data seem more representative of a still non-wetted soil whereas the BEST, BB and PI data appear more appropriate to characterize a porous medium at some advanced stage during a rainfall event. Additional investigations carried out on different soils would allow to better establish the relationship between the determination procedure of Ks and the intended use of the data
Verifica di un nuovo algoritmo BEST per l’analisi di prove Beerkan mediante curve di infiltrazione simulate numericamente con Hydrus 2D/3D
No full textL'interpretazione e la simulazione dei processi idrologici sono rese complesse dall’elevata variabilità spaziale e temporale delle proprietà idrodinamiche del suolo, che impongono campagne di misura intensive e onerose. I metodi di misura in campo dovrebbero essere allora quanto più semplici e rapidi possibile. L’infiltrazione in condizioni di ponding sulla superficie è regolata dalla sorptività, S, e dalla conducibilità idraulica del suolo saturo, Ks. Questi due parametri possono essere determinati in campo con la cosiddetta procedura BEST (Beerkan Estimation of Soil Transfer parameters), a partire da misure di infiltrazione del tipo Beerkan. I tre algoritmi BEST attualmente disponibili presuppongono la conoscenza del contenuto idrico del suolo all’inizio e alla fine del processo di infiltrazione. Recentemente, è stato introdotto un nuovo algoritmo BEST, denominato BEST‐OI (BOI, OI = Only Infiltration), che rende possibile la stima di S e Ks in assenza di informazioni sul contenuto idrico del suolo. L’algoritmo BOI considera le fasi transitoria e stazionaria del processo di infiltrazione. Finora, questo nuovo algoritmo è stato testato solo con riferimento a curve di infiltrazione sintetiche ottenute analiticamente utilizzando il modello implicito di Haverkamp. In questa indagine, la capacità di BOI di determinare S e Ks è stata verificata utilizzando curve sintetiche ottenute numericamente con Hydrus 2D/3D. Lʹanalisi ha dimostrato che lʹalgoritmo BOI fornisce in genere stime di S e Ks accurate, con la sola eccezione di un suolo silty‐clay‐loam. Ulteriori test con dati numerici e sperimentali renderanno possibile una definizione maggiormente esaustiva delle potenzialità e dei limiti del nuovo algoritmo BEST
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
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