1,720,964 research outputs found
FIELD-SCALE ASSESSMENT OF NUTRIENT AND SOIL LOSSES DURING SURFACE RUNOFF EVENTS, IN AN OLTREPÒ PAVESE (SOUTHERN LOMBARDY ¿ ITALIAN REGION) VINEYARD HILL.
Full text linkThe aim of my Ph.D. work was to investigate sediment transport and nutrient content in runoff water from an agricultural system.
The study was carried out in a representative sites of the Oltrepò Pavese, in Lombardy region (northern Italy) in a vineyard equipped with instruments for measuring volume and rate of runoff and collecting samples to determine the amount of soil loss related to each rainfall event. The site was equipped with a weather station, which included a recording rain gauge.
The analysis was done under natural rainfall condition during the period December 2008 - December 2012, in which 15 rainfall events were recorded.
The first step of the research was to equip the field plot with a collection system. An in-field runoff multislot collector, exploitable for monitoring nutrients, pesticides and sediments loadings in runoff, was installed in the field and was improved with a home made level reading system able to measure with high temporal resolution, the runoff rate variation. Subsequently every runoff event was investigated. Samples were taken and analysed for quantifying the sediments loaded from runoff event and the nutrient losses from the system. Samples were also analysed with a laser diffraction technique in order to characterize, in natural conditions, the distribution of sediment grain-size transported by rainfall runoff
Technical approach for the measurement of surface runoff
No full textIn this paper we describe practical application, design and installation of an in-field runoff collector exploitable for monitoring nutrients, pesticides and sediments loadings in runoff, improved with a home made level reading system able to measure with high temporal resolution, the runoff rate variation.
This configuration simplifies and lower the cost of conventional instruments used for measuring runoff. A multislot divisor was used to reduce the volume of runoff and plastic tank were use to collect it. An electro-mechanic type, floating level transducer was proposed. The homemade level reading system is composed of three parts: floating level transducer, signal conditioning system and data storage. The total cost for entire system is approximately € 642
Analisi del contenuto idrico del suolo per due differenti sistemi di irrigazione
Full text linkL’esigenza di attuare interventi mirati alla razionalizzazione della risorsa idrica è avvertita in modo specifico nel comparto agricolo, in considerazione dei notevolissimi volumi di acqua richiesti per il compimento del ciclo produttivo delle coltivazioni. La scelta del sistema di irrigazione risulta determinante per il contenimento delle perdite e il miglioramento dell’efficienza d’irrigazione. A tal proposito è stata condotta una sperimentazione in Pianura Padana su due appezzamenti per confrontare due differenti sistemi irrigui: per gravità tramite scorrimento superficiale, e per aspersione con pivot ad ala imperniata. Il monitoraggio dei contenuti idrici è stato eseguito a diverse profondità, sia con un metodo diretto e discontinuo (metodo gravimetrico), sia con metodo indiretto e continuo, che accoppia la misura tensiometrica in campo, allo studio della curva di ritenzione idrica in laboratorio. La prova di campo ha dimostrato una maggiore perdita per percolazione nel sistema a scorrimento, confermando la bassa efficienza del metodo stesso e la necessità di apportare maggiori volumi complessivi
Tecnica di misura dei fenomeni di ruscellamento superficiale
Full text linkIl suolo è una risorsa non rinnovabile capace di assicurare funzioni essenziali non solo a livello ambientale ma anche sociale ed economico, assumendo quindi un ruolo centrale nel contesto di sostenibilità dell’agricoltura. Tuttavia il suolo è soggetto ad un continuo degrado dovuto in particolare al fenomeno dell’erosione che non solo ne influenza negativamente le proprietà nutritive ma diventa una potenziale fonte di inquinamento per le acque superficiali. I fenomeni erosivi sono influenzati da notevoli fattori che il più delle volte vengono meglio descritti se studiati a scala di campo, piuttosto che a piccola scala. Inoltre gli alti costi degli strumenti e la quantità enorme di ruscellato limitano il più delle volte il numero di siti che possono essere studiati. Sono stati quindi sperimentati strumenti, per parcelle di più ampia superficie, che permettono di ripartire l’acqua ed il ruscellato e di ridurre in questo modo il campione raccolto mantenendolo rappresentativo. In questo lavoro viene presentata l’applicazione pratica di uno di questi strumenti di misura opportunamente adattato che permette con ampia soluzione temporale di monitorare i fenomeni di ruscellamento superficiale a scala di campo
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
AQUATER Software as a DSS for Irrigation Management in Semi-Arid Mediterranean Areas
No full textIrrigation management at district or regional scale can be dealt using ecological process-based models and remote sensing data. Simulation crop models simulate at a certain time step the main biophysical variables determining crop photosynthesis and water consumption rates. The research consists in an integrated approach to combine field data, simulation crop model and remote sensing information. Detailed data sets related to topography, soil, climate and land cover were collected and organized into a Geographic Information System, which is routinely updated with remotely sensed images. The code implementation of these two models allows for an improvement of simulation reliability for the crop types considered in the present study in Mediterranean area. Remote sensing images detected by optical and radar satellite sensors at different spatial scales (from 10 to 50 m) have been collected over the analyzed crop cycles. Therefore, remote sensing information about land use and leaf area index (LAI) are assimilated dynamically by the model, to increase the effectiveness of simulation. The integration of crop and water dynamics models with the updated remote sensing information is a Decision Support Systems, AQUATER software, able to integrate remote sensing images, to estimate crop and soil variables related to drought, and subsequently to assimilate these variables into a simulation model at district scale. The significant final outputs are estimated values of evapotranspiration, plant water status and drought indicators. The present work describes the structure of AQUATER software and reports some application results over 2006 and 2007 cropping seasons in Capitanata, South-East Italy. This region has been divided in simulation units cropped by tomato (Lycopersicon lycopersicum L.), sugar beet (Beta vulgaris L. var. saccharifera) and durum wheat (Triticum durum Desf.). Two types of comparison have been carried out: (i) between some tomato observed and simulated data, and (ii) between “LAI Forcing” and “No LAI Forcing” simulated data. LAI Forcing data have been detected by remote sensing over the crop cycle and over the whole region. The model showed a relevant coherence between observed and simulated data (RRMSE = 32, 55, 30% for above ground biomass, LAI and soil water content, respectively). In the case of the application of the LAI Forcing procedure, since simulated LAI are lower than the observed values, as a consequence, simulation results underestimate
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
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