1,720,974 research outputs found
Biomass sorghum production risk assessment analysis: A case study on electricity production in the Po Valley
No full textThe risk associated to the production of biomass sorghum (Sorghum bicolor (L.) Moench) to feed a power
plant in the Po Valley (Italy) was studied with a modelling approach. Available biomass was modelled by
CropSyst, coupled to a “sorghum haying model”, using three sorghum genotypes, of contrasting earliness
(early, medium-late and late), on a mosaic of virtual farms created in the target cropping area. The energy
performance, from cradle to farm gate, of the biomass production system was performed calculating
Energy Return on Investment (EROI), Net Energy Gain (NEG) and Energy Use Efficiency (EUE).
The highest baled biomass (14.0 Mg DM ha-1y-1) was obtained with the early maturity type that had
less haymaking failures (6.9%), followed by the late and medium-late genotypes. As a consequence, the
early maturity type had the highest probability of exceeding the biomass needs of the power plant on a
cropping area of 4222 ha. The early genotype also had the highest EROI (14.8) and NEG
(205.6 GJ ha-1y-1) and the lowest EUE (1.06 GJ Mg-1 DM y-1).
To achieve a 0.5 probability to exceed the target biomass production, the area to be cultivated should
be 4558, 5160 and 4962 ha for the early, medium-late and late genotypes, respectively
Agrivoltaic systems to optimise land use for electric energy production
No full textA system combining soil grown crops with photovoltaic panels (PV) installed several meters above the ground is
referred to as agrivoltaic systems. In this work a patented agrivoltaic solar tracking system named Agrovoltaico®,
was examined in combination with a maize crop in a simulation study. To this purpose a software platform was
developed coupling a radiation and shading model to the generic crop growth simulator GECROS. The simulation
was conducted using a 40-year climate dataset from a location in North Italy, rainfed maize and different
Agrovoltaico configurations (that differ according to panel density and sun-tracking set up). Control simulations
for an irrigated maize crop under full light were added to results.
Reduction of global radiation under the Agrovoltaico system was more affected by panel density (29.5% and
13.4% respectively for double density and single density), than by panel management (23.2% and 20.0% for suntrack
and static panels, respectively).
Radiation reduction, under Agrovoltaico, affected mean soil temperature, evapotranspiration and soil water
balance, on average providing more favorable conditions for plant growth than in full light. As a consequence, in
rainfed conditions, average grain yield was higher and more stable under agrivoltaic than under full light. The
advantage of growing maize in the shade of Agrovoltaico increased proportionally to drought stress, which
indicates that agrivoltaic systems could increase crop resilience to climate change.
The benefit of producing renewable energy with Agrovoltaico was assessed using the Land Equivalent Ratio,
comparing the electric energy produced by Agrovoltaico cultivated with biogas maize to that produced by a
combination of conventional ground mounted PV systems and biogas maize in monoculture. Land Equivalent
Ratio was always above 1, it increased with panel density and it was higher with sun tracking than with static
panels. The best Agrivoltaico scenario produced twice as much energy, per unit area, as the combination of
ground mounted PV systems and biogas maize in monoculture. For this Agrivoltaico can be considered a valuable
system to produce renewable energy on farm without negatively affecting land productivity
Coupling sorghum biomass and wheat straw to minimise the environmental impact of bioenergy production
No full textThe reform of the European sugar market in 2006 paved the way for the development of new agricultural
value chains in the Po Valley (Italy). A value chain based on the use of biomass sorghum (Sorghum bicolor
(L.) Moench) to produce electricity in a medium-scale power plant was investigated. A Life Cycle
Assessment was carried out to explore the environmental impact and energy performance of power
generation from three biomass sorghum genotypes characterized by different earliness (early, mediumlate
and late) in the Po Valley (Italy). To fully cover the plant needs, sorghum was complemented by
winter wheat straw. Productivity and losses of sorghum for the past 39 years as simulated in Serra et al.
(2017) were used to produce a probability distribution of environmental impacts. Soil organic carbon
change relative to the straw removal and sorghum incorporation in soil as well as indirect land use
change CO2 emissions for the substitution of sugar crops with energy crops were also accounted for. To
test the influence of the assumptions an extensive sensitivity analysis over several parameters was
performed. The lowest average GHG emissions (68.9 g CO2eq.MJ1) were achieved with the late genotype
while medium-late and early genotypes emitted 73.5 g CO2eq. MJ1 and 76.8 g CO2eq.MJ1, respectively.
Despite the conservative assumptions, the bioenergy system contributed on average 47.7% less GHG than
a natural gas power plant. In the lowest productivity years the sorghum based energy system emitted
52% less GHG than the Italian electricity mix.
Overall, when harvesting and bailing failed due to unfavourable weather conditions, the lowest GHG
emissions were found, thanks to the increased replacement of sorghum with straw. In fact, soil incorporation
of sorghum biomass resulted in more nutrients added to the soil than with incorporation of
wheat straw. Considering that GHG emissions decreased linearly when sorghum biomass yield increased,
the highest reductions of GHG were found with late genotypes, that produced the highest yields. The
lowest GHG emissions were found when harvesting failed, as the fertilizer debit of straw is lower than
the fertilizer credit of sorghum. However, since carbon and nutrients storage in the soil is not rewarded
monetarily, this option will not correspond to an optimal profit as the risk of failures are highest with late
genotype.
All other environmental impacts assessed were higher for the sorghum based system than for the
fossil alternatives. It was found that the presence of DeNOx SNCR (Selective Non-Catalytic Reduction)
technology achieved the expected mitigation of acidification potential and photochemical oxidant formation
but at the expenses of an increased climate change impact, due to additional N2O emissions
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
Studio delle fasi vegetativa e riproduttiva in radicchio rosso di Chioggia (Cichorium intybus L., var. silvestre Bischoff): influenza di fattori climatici e colturali
No full textDottorato di ricerca in agronomia ambientale. 8. ciclo. Supervisori F. Pimpini e G. Prosdocimi GianquintoConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
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
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