1,721,033 research outputs found
The performance of an air-assisted sprayer operating in vines
No full textThe performance of a sprayer fitted with two vertical adjustable air outlets has been studied in vineyards investigating the effects of changing the fan speeds (1400, 2000 and 2500/min) and the direction of the air-jet (90 and 120° backward angle of the outlet side deflectors in relation to the treated row). Laboratory measurements were made before the field trials in order to define the operating characteristics of the sprayer. The sampling methodology in the vineyard was based on a framework and a system of intersecting nylon threads dividing the canopy into elementary volumetric zones. The spray flux entering and leaving the canopy, and the losses to the ground and to the air were measured. The spray coverage on the leaves at different heights and depths in the canopy has been also quantified. In all the tests, the air outlets were adjusted to localize the spray application to the appropriate heights determined by the growth of canopy. Considering the spray deposit and the environmental losses, the best results were observed with the 120° backward angle of the outlet side deflectors and the low and medium fan speeds. The effect of the fan speed compared with that of the direction of the air stream appeared more evident. The spray losses doubled by increasing the fan speed and frequently these losses were not limited to the treatment area but drifted outside. The degree and the uniformity of the spray coverage were strongly influenced by the high fan speed. © 2000 Silsoe Research Institute
Evaluation of a prototype spreader in the distribution of poultry manure
No full textA study of a prototype spreader evaluated the distribution of four poultry manures differing in terms of composting degree and moisture content. The chemical and physical properties such as wet bulk density, moisture content, and static frictional characteristics of the manures were evaluated. The prototype was set up for orchard and arable crops and the spinner speed and point of delivery of the organic fertilizer onto the spinners were adjusted. When properly adjusted it was suitable for broadcast manure distribution and in bands. In the former, an increase in spinner speed improved the throwing width and effective swath width. The best results for the point of delivery of the organic material were achieved by moving the point of delivery away from the center of the spinners. In the band distribution, the best results were observed when the point of delivery coincided with the center of the spinners and spinner speed was low. The physical properties of the fertilizers influenced the distribution pattern. The poorest results were observed in the distribution of manure with large particles and high moisture content. A proper management process of poultry manure is recommended for improving the distribution quality
Lateral stability performance of articulated narrow-track tractors
Full text linkA tractor losing lateral stability starts to rollover. It is a matter of fact that tractor lateral rollover accidents are one of the most frequent causes of death and injuries for farmers. Consequently, tractors are fitted with a specific protective structure to minimize the consequences for the driver during the rollover (ROPS). The narrow-track tractor, designed to operate in vineyards and orchards, is a tractor category with a very narrow track width and the risk of rollover is higher. The aim of the study was to evaluate the compact narrow-track tractor types commercially available, designed to mount a cantilever engine in the forward position with effects on the Center of Gravity (CoG) because more than 50% of the tractor weight is loaded on the front axle, and, specifically, the articulated narrow-track tractors where the stability is affected by the pivot point connecting the two tractor bodies. As a consequence of the typical tractor design of articulated tractors, during the steering action the line passing through the front and rear tire contact points on the ground changes, influencing the tractor’s stability. The approach of the research was based on reproducing the lateral stability tractor condition by developing a kinematic model, with the goal to virtually simulate the tractor behavior and to calculate the lateral stability angle for articulated tractors. The innovative contribution of this paper was the tractor articulation joint modeling, assuming a virtual pivot point to reproduce two relatives’ rotations between the front and rear bodies of the tractor: vertical (yaw angle) and longitudinal (roll angle) rotations. The lowest value of the stability angle was 39.3◦, measured at −35◦ yaw angle. The model at the tractor design stage will allow adjusting of the tractor parameters to improve the lateral stability performance
The use of an electronic beet to evaluate sugar beet damage at various forward speeds of a mechanical harvester
No full textMechanical harvesting strongly affects the quality of sugar beets, mainly in terms of root injuries, tare, and extracted sugar. In Mediterranean countries, the effects of sugar beet damage are more critical because of the warm and humid climate at harvesting time. In order to investigate the dynamic interaction between mechanical tools and roots, electronic devices have been developed in some European countries for measuring impacts experienced by roots when passing through the harvesters. At the University of Bologna, an electronic beet with a 4905 m/s2 tri-axial accelerometer was developed in 1998. This device was used in a field trial for measuring and recording impacts in terms of peak acceleration, duration, and velocity change during impact. The device was placed into the soil in place of a real beet and then harvested by a six-row self-propelled harvester, which was tested at four different forward speeds. Assessments of the level of damage on the harvested sugar beets were also carried out according to the IIRB international method. The aim of the study was to evaluate how different forward speeds tested on a single harvester can affect damage to the roots, to assess the damage caused at each step of the harvesting process, and to find a correlation between damage and impacts. Mechanical parameters recorded by the electronic beet were referenced to three specific positions, defined as A, B, and C zones, within the harvester. The ANOVA results in A zone, composed of lifting shares and roller bed, and in B zone, composed of transfer web and turbines, showed a statistical significance. In C zone, composed of tank elevator and tank, the variables had no statistical significance. The results of the trial showed that A zone had the highest values of the variables. A harvester forward speed of 6 km/h caused the fewest taproot breaks and bruises. A linear model describing the relationship between taproot breaks and impact velocity change showed a statistical significance for A zone, while no significance was determined for B zone
Energy absorption in actual tractor rollovers with different tire configurations
Full text linkIn order to better understand the complexities of modern tractor rollover, this paper investigates the energy absorbed by a Roll-Over Protective Structure (ROPS) cab during controlled lateral rollover testing carried out on a modern narrow-track tractor with a silent-block suspended ROPS cab. To investigate how different tractor set-ups may influence ROPS and energy partitioning, tests were conducted with two different wheel configurations, wide (equivalent to normal ‘open field’ operation) and narrow (equivalent to ‘orchard/vineyard’ operation), and refer to both the width of the tires and the corresponding track. Dynamic load cells and displacement transducers located at the ROPS-ground impact points provided a direct measurement of the energy absorbed by the ROPS cab frame. A trilateration method was developed and mounted onboard to measure load cell trajectory with respect to the cab floor in real-time. The associated video record of each rollover event provided further information and opportunity to explain the acquired data. The narrow tire configuration consistently subjected the ROPS cab frame to more energy than the wide tire arrangement. To better evaluate the influence of the ROPS cab silent-blocks in lateral rollover, static and dynamic tests were performed. The results confirm that tires influence the energy partition significantly and that further understanding of silent-blocks’ dynamic performance is warranted
Concept and design of the ROPS for a small articulated tractor for extreme sloped vineyards
No full textA new reversible wheeled articulated tractor has been designed and realized by WM s.r.l.
(Prato all’Isarco, BZ, Italy) in collaboration with UNIBZ and FIR, to address the problem of
working in terraced vineyards trained with the so-called “pergola” system, very common in
mountain areas.
The whole design process of this tractor was characterized by a constant dialogue between
engineers and a selected pool of farmers, representative of final users, to have a product as
much as possible answering to the users’ needs and, hence, free from future requests of
design changes, according to the logic of Concurrent Engineering. In particular, conceiving
and designing a Roll-Over Protective Structure (ROPS) suitable to equip this small tractor
was a real engineering challenge: many design constraints, coming from the difficult environment
in which this tractor will operate and resulting from the very particular design of the
front part of the tractor, had to be matched with the (dimensional, structural) requests stated
from the OECD code 7 used for ROPS strength tests.
The operating environment for this tractor imposed reduced dimensions to the external outline
of this vehicle: vineyards inter-rows are very narrow (often lower than 1.00 m), as well as
spans under the arbours (commonly ≤1.80 m, often 1.60 m). A high compactness of the vehicle
was obtained by adopting an unconventional architecture for this tractor, i.e. an articulated
body with a Diesel engine placed in the front part, a reversible driving seat directly
placed on the motor, and the rear part acting as implement-carrier. Also the ROPS has some
peculiarities, studied to match safety-volume requirements with the possibility for farmers of
further reducing the overall height, if needed in some very narrow passages. In fact, the tractor
was equipped with a non-removable, tiltable and telescopic rear-mounted ROPS combined
with a top horizontal element and a frontal protection for the driver’s feet.
The absence of a conventional steering wheel (the tractor is driven by a cloche) and of an
engine-bonnet in front of the driver make this ROPS absolutely unique and not-provided for
by the norm; this latter fact puts two important questions to the testers, respectively on: (1)
how defining the front outline of the clearance zone (i.e. the point “D” of OECD code 7, fig.
7.1.a p. 23), usually defined in relation with the forward external edge steering wheel, and (2)
how identifying the hard points of the tractor capable of supporting the whole mass of the
overturned vehicle (i.e. the points defined on the basis of the imaginary ground plane).
Thanks to a careful interpretation of the inspiring principles of the norm and to the great experience
of the staff of the University of Bologna, these problems were successfully overProceedings
International Conference of Agricultural Engineering, Zurich, 06-10.07.2014 – www.eurageng.eu 2/8
come respectively by (1) limiting the clearance zone to the vertical line passing through the
point “C” (OECD code 7, fig. 7.1.a p. 23), thus operating even with a higher safety level, and
(2) by using the external edge of the feet protective structure to define the clearance zone
and the virtual ground plane in case of overturning
Special Issue: Engineering advances to improve the safety of agricultural machines
No full textAgriculture is one of the most hazardous of commercial sectors with every year many of its workers suffering occupational accidents and ill health. The International Labour Organisation (ILO) defines agriculture as the second greatest source of employment after services with more than a third of the world’s labour force. This Special Issue with the open call for papers aimed to demonstrate the importance of engineering advances in relation to the safety of agricultural machines with the main purpose of encouraging and investigating new research opportunities targeted improve human safety
A Review of Current and Historical Research Contributions to the Development of Ground Autonomous Vehicles for Agriculture
Full text linkIn this study, a comprehensive overview of the available autonomous ground platforms developed by universities and research groups that were specifically designed to handle agricultural tasks was performed. As cost reduction and safety improvements are two of the most critical aspects for farmers, the development of autonomous vehicles can be of major interest, especially for those applications that are lacking in terms of mechanization improvements. This review aimed to provide a literature evaluation of present and historical research contributions toward designing and prototyping agricultural ground unmanned vehicles. The review was motivated by the intent to disseminate to the scientific community the main features of the autonomous tractor named BOPS-1960, which was conceived in the 1960s at the Alma Mater Studiorum University of Bologna (UNIBO). Jointly, the main characteristics of the modern DEDALO unmanned ground vehicle (UGV) for orchard and vineyard operations that was designed recently were evaluated. The basic principles, technology and sensors used in the two UNIBO prototypes are described in detail, together with an analysis of UGVs for agriculture conceived in recent years by research centers all around the world
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
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