1,720,984 research outputs found
Simulation modelling of mechanical systems for intra-row weeding in a precision farming approach
Full text linkAim of study: To test new approaches to perform mechanical weeding inside the row in horticulture and tree fruit fields. The idea is to weed the row by skipping the crop by means of a rotating system instead of a traditional crosswise one.
Area of study: North of Italy.
Material and methods: Numerical models have been developed to simulate mechanical weeding over time by generating numerical maps to quantify the different kind of worked areas.
Main results: Considering the efficiency of weed control on the row, the rotating plant-skipping system with vertical axis (RPSS-VA model) with two working tools gives the best performance index (1.1.RWA% = 95.9%). A similar performance can be obtained by the crosswise displacement plant-skipping system, but with very high crosswise translation velocity (with va/vr ratio = 1/5, 1.1.RWA% = 94.5%). With regard to the outwards worked area the RPSS-VA models give the best performances (2.2.%OWAR index from 127.2% up to 282.3%). To reduce the worked area outside the row, the FBTS models give lower index (2.1.OWAR%), while the RPSS-HA works only on the row, but with the lower 1.1.RWA% index among all tested models (55.8%).
Research highlights: Rotating systems resulted more efficient than traditional ones, and provide considerations on the use of electric drive power instead of hydraulic one. This study highlights also the need of new approaches in designing lighter working tools. Lastly, the proposed classification of the worked areas could be used as reference standard
Hemp seed mechanical harvesting efficiency analysis
No full textAbstract View references (7)
Mechanical harvesting of hemp seeds is performed using machines developed for other grain crops in order to allow an easier insertion of hemp cultivation into consolidated production area trying to avoid further purchase of complex and expensive machinery on the territory. On the other hand, it involves the use of machines with low harvesting efficiency because the hemp plants are considerably different from the cereal grain plant having a biomass production 2-3 times bigger than grain in weight. However, hemp seed is harvested when the seed begin to scatter. All these factors combined, lead to a complex setting of the combine harvester. In this paper, harvesting tests were performed in order to evaluate the efficiency of mechanical harvesting of hemp seeds with conventional combine harvester with cereal head, some harvest tests were carried out by varying only the machine setting without significant modifications of the machine. The experimental design included the division of the field into 4 plots, cultivated with a seeding density D1 (60 pt / m2) and D2 (30 pt / m2). Only two plots received foliar fertilization. Each plot has been divided sub-parcels collected with two working speeds of the machine: V1 (3 kmh-1) and V2 (5 kmh-1). The combination of plots configuration provided 8 experimental. The total seed yield per m2 has been obtained handpicking the seeds in experimental plots divided by agronomic pre-treatments and then cleaned. The harvest efficiency has been calculated comparing the total seed yield with the mechanical seed harvesting using different settings of combine harvester. This work showed an average harvesting efficiency of 68%. Higher efficiency percentage has been obtained on plots with 60 plants/m2 density and harvested at V1 speed. This experience has highlighted some limitations due to the general use of non-specific hemp solutions for harvest, but this result can be explained with different cultivation techniques of hemp. © 2018 ETA-Floren
Chip quality as a function of harvesting methodology
No full textThe study aimed to evaluate the aboveground dry biomass production and the quality of fresh and dried chips obtained by eight different species grown under SRC culture and subjected to two harvesting systems and chipping devices.
The present study was part of a long project including different species and management regime of a SRC plantation, which was established in 2007 on a level soil at the Improsta experimental farm (Eboli, Salerno, Italy).
In 2015, It was realized a comparative test chipping eight different species grown under SRC system: Fraxinus oxyphylla, Robinia pseudoacacia, Salix alba, Populus nigra (Limatola) and four hybrid genotypes of Populus x euroamericana (Grimminge, Vesten, Hoogvorst, Muur), harvested at the end of the first three years rotation coppice (2012-2014).
The trees were chipped both fresh and dried. The fresh biomass was harvested and chipped in a single phase by a self-propelled forage harvester Claas Jaguar 880 (nominal power of 353 kW), equipped with GBE biomass head for trees cutting and harvester feeding. The dried biomass was chipped by a forestry wood disk chipper Farmi Forest CH 260, after two months of storage in the field.
The plantation mean of the standing aboveground dry biomass was greater for P. nigra Limatola, followed by F. oxyphylla. As consequences, they showed respectively a high mean annual increment of aboveground dry biomass of 14.38 and 10.16 t ha-1 year-1. The first coppice rotation dry biomass yield was not significantly different for Hoogvorst and Vesten. In contrast to the biometric attributes clone Muur showed a low aboveground dry biomass production, followed by Grimminge and S. alba with a significantly lower production.
Moisture content of the fresh biomass ranged between 42.59 % and 56.84 % for black locust and willow, respectively. The dried biomass ranged, instead, between 17.32 % for willow and 36.80 % for Populus nigra. The average reduction of moisture content after storage was 43.97 % with the highest and lowest rate of dehydration for willow (69.53 %) and poplar Vesten (28.70 %).
Concerning the particle size distribution, the presence of large chips (63-45 mm) and oversized (> 63 mm) were extremely limited for the fresh chips, while it is considerably higher for the dried chips. Fractions ranging from 45 to 3 mm were the most represented for all species and treatment, accounting between 84.09 % and 90.65 % for the fresh chips, and 74.15 % and 85.68 % for the dried chips. The comminution carried out with the disk chipper on dried biomass always leads to a decrease in the percentage of accept (45-3 mm fractions) respect to the same fresh species chipped by drum chipper
Mechanical thinner of apricot fruitlet
No full textThe aim of this study is to test this new thinner machine on apricots fruitlets, identifying the suitable working speed that best combine the most thinning effect in absence of visible damage of the branches and the remaining fruits.
The machine is composed by a rotor equipped with radial rods on a central axe mounted in a rear tree point linkage of a tractor. Trials were carried out in March-May 2016 in an apricot orchard sited in Cesena (FC). The experimental was designed to compared mechanical thinning at different working speed (1.11 and 0.83 m/s) and hand thinning on green fruits (2 ≤ Ø ≤ 2.5 cm). The thinning effect was evaluated counting fruits remained from 40 branches randomized choice in upper and down part of four plants replicates. After the mechanical thinning, it was performed a manual thinning of finishing, aimed to eliminate the fruits too close together on the branch and, in general, ensure a uniform fruit set on the tree. Time required for thinning was measured in the trees mechanical thinned and compared with those one thinned only Handily (control).
The two different working speeds gave two different thinning intensity: at 0.83 m/s fallen fruits were the 44 % of the total while at 1.11 m/s the 47 %. The thinning effects depends on branches length and at 1.11 m/s in branches of length over 35 cm was recorded the highest fruit reduction (50.3 %) and the lowest (44.4 %) in branches of length of less than 15 cm. Different were the results obtains in the thesis at 0.83 m/s in fact the percentage of fruit reduction was included between the 47.5 % of branch with a length greater than 35 cm and the 41.3 % of branches with a length of less 15 cm.
Mechanical thinning can produce a net economic impact on apricot cultivation and in some cases, can replace the manual thinning and reduce considerable the labor costs
Two steps Arundo donax L. Harvesting in South Italy
No full textThe aim of this study was to evaluate the performance of two-pass harvesting system on giant reed (Arundo donax). The biomass was shredded, dried in the field and baled for logistic chain and storage. The first step was cutting and shredding with a specific shredder for biomass crops rear mounted in agricultural tractor and in the second time the Arundo biomass was harvested after more day of drying in the field with continuous monitoring of the biomass moisture content.
This harvesting system presents some advantages such as: the possibility of immediate and long storage of biomass (moisture content 12-14 %), better use of farm mechanization for hay making, diversified use of the dried biomass (combustion and II° generation ethanol), fuel consumption in line or even less than other ordinary crops present in that area.
The test showed technical and energy aspect of the harvest technology with the adoption of only one specific machine while the other are normally presents in the farm. The machine adopted for shredder, designed and developed by Italian constructor for more biomass herbaceous crops (Arundo, Sorghum, Panicum, Mischantus, etc.) is indicated for high vegetative developed crop and can spread the product in all soil surface or windrowing. The tests were conducted in Southern Italy (Campania region) in an experimental farm of Torre Lama (SA). The tests have showed a good performance slightly lower than 1.5 ha h-1 (1.47) with operative speed of 4.88 km h-1. The hourly production taken as a reference is a theoretical production of 58.35 t ha-1 with a biomass moisture of 42.51 %. After field drying, the biomass is baled with round baler
Double-pass harvesting system on giant reed in south Italy
No full textAbstract View references (15)
The aim of the study is to evaluate the possibility of two step harvesting system for giant reed. The biomass was shredded and dried in the field, in second time was baled and storage. First step was cutting and shredding with a specific shredder for biomass crops rear mounted in agricultural tractor and in the second time the Arundo biomass was harvested after more day of drying in the field with continuous monitoring of the biomass moisture content. This harvesting system presents some advantages such as: the possibility of long storage of biomass (moisture content lover 14-15%), baled with a farm mechanization for hay making, possibilities of diversified use of the dried biomass (combustion and II generation ethanol). The test showed technical and energy aspect of the harvest technology but there is necessary one specific machine for shredder while the other are normally presents in the farm. The machine adopted for shredder, designed and developed by Italian constructor for more biomass herbaceous crops (Arundo, Sorghum, Panicum, Mischantus, etc.) is indicated for high vegetative developed crop and can spread the product in all soil surface or windrowing. The tests were conducted in the South of Italy (Campania region) in an experimental farm of Torrelama. The tests have showed a good performance slightly lower than 1.5 ha h-1(1.47) with operative speed of 4.88 km h-1. The hourly production is 58.35 t ha-1with a biomass moisture content of 42.51%. After field drying the biomass are baled and storage. © 2018 ETA-Florence Renewable Energies
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
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