Search results for "SPREAD"
showing 10 items of 292 documents
Optimizing Hough transform for fertilizer spreading optical control
2006
International audience; In Europe, centrifugal spreading is a widely used method for agricultural soil fertilization. In this broadcasting method, fertilizer particles fall onto a spinning disk, are accelerated by a vane, and afterward are ejected into the field. To predict and control the spread pattern, a low-cost, embeddable technology adapted to farm implements must be developed. We focus on obtaining the velocity and the direction of fertilizer granules when they begin their flight by means of a simple imaging system. We first show that the outlet angle of the vane is a bounded value and that its measurement provides the outlet velocity of the particle. Consequently, a simple camera un…
A 3-D simulation with virtual stereo rig for centrifugal fertilizer spreading
2012
International audience; Stereovision can be used to characterize of the fertilizer centrifugal spreading process and to control the spreading fertilizer distribution pattern on the ground reference. Fertilizer grains, however, resemble each other and the grain images contain little information on texture. Therefore, the accuracy of stereo matching algorithms in literature cannot be used as a reference for stereo images of fertilizer grains. In order to evaluate stereo matching algorithms applied to images of grains a generator of synthetic stereo particle images is presented in this paper. The particle stereo image generator consists of two main parts: the particle 3D position generator and…
A virtual spreader to overcome experimental limits: Example of use to deepen the meaning of the transverse coefficient of variation
2017
International audience; A virtual spreader was modelled by combining the use of theoretical motion equations and statistical distributions of input parameters. These parameters were deduced from experimental measurements using a custom-made spreader, an imaging system, a particle impact recording device and a rotating test bench. Using this model, each spread pattern was computed using a random selection of values following the statistical distribution of each input parameter. Using simulations, we quantified how the CV value was affected by application rates and measurement protocols whatever spreader settings. Simulations showed the CV value and its measurement variability increased when …
Economies d'agglomération et configurations spatiales dans les espaces ruraux
1997
The question to be addressed here is that of the agglomeration/dispersion forces that are likely to account for the location of people and jobs in rural areas and the way they explain spatial patterns in rural areas depending on urban influence. Economic geography models may provide suitable tools with which to investigate the organization of rural areas. We first review these models, focusing on dispersion forces, which rest basically on land consumption and transport costs. We suggest then a set of hypotheses concerning the main forces at work in rural areas. Intensity of agglomeration economies is hypothesized to be related to the urban size, which in turn induces increasing land rents a…
Fouille d’un quartier funéraire des Ier et IIe s. dans le suburbium de Soissons/Augusta Suessionum : aires de crémation et inhumations d’enfants
2012
In the beginning of 2008 a preventive excavation has been conducted on about 1200 m2 of a large antique cemetery situated upon the butte Saint-Jean at Soissons (Aisne). In this cemetery, almost unknown, located south-west of the Roman town Augusta Suessionum a consistent activity in the part being excavated took place between the Augustan era and mid 2nd c. The total number of inhumations uncovered is 186 (mainly of infants). Cremations were executed from the very beginning altogether with inhumations, in more or less close proximity to them according to periods, then became predominant to the detriment of burials which were just previously arranged. Different structures clearly connected t…
Mācību temata “Izklājlapas” apguves organizēšana atbilstoši automehāniķa profesijai modulī "Informācijas un komunikācijas tehnoloģijas"
2022
Pieredzes darba mērķis ir izstrādāt un aprobēt automehāniķa profesijai atbilstošus mācību materiālus temata apguvē “Informācijas un komunikācijas tehnoloģijas” modulī. Profesionālās izglītības iestādēs ir svarīgi pielāgot apgūstamos tematus audzēkņu izvēlētajām profesijām, lai saturs būtu jēgpilns, saistošs. Darba uzdevumos ietilpst veikt mācību procesa plānošanu, organizēšanu un vērtēšanu atbilstoši teorētiskajām nostādnēm, noskaidrot profesijai atbilstošās vajadzības, veikt izvērtējumu, apkopot un izvērtēt audzēkņu pašvērtējumu par temata apguvi. Darba rezultātā izstrādātie materiāli aprobēti mācību stundās, secināts, ka komunikācija ar nozares speciālistiem ir būtiska. Lai arī audzēkņu u…
Simulation of granular organic fertilizer application by centrifugal spreader
2021
There is no specialized equipment designed to spread granular cylindrical organic fertilizer in the soil. There are also no rational recommendations available on how to spread this type of fertilizer. Mineral fertilizer spreaders are most often used for spreading granulated organic fertilizer. However, these fertilizers are significantly different from mineral fertilizers. Due to these differences, organic granular fertilizers often are spread unevenly, and the fertilizer does not reach the required working width. Furthermore, the rate of spreading is not accurate, and the fertilizer is often crushed too much. The objective of this research is to develop a simulation model for granular orga…
Comparative sclerochronology of modern and mid-Pliocene (c. 3.5Ma) Aequipecten opercularis (Mollusca, Bivalvia): an insight into past and future clim…
2009
Records of environment contained within the accretionarily deposited tissues of fossil organisms afford a means of detailed reconstruction of past climates and hence of rigorous testing of numerical climate models. We identify the environmental factors controlling oxygen and carbon stable-isotopic composition, and microgrowth-increment size, in the shell of modern examples of the Queen Scallop, Aequipecten opercularis. This understanding is then applied in interpretation of data from mid-Pliocene A. opercularis from eastern England. On the basis of oxygen-isotope evidence we conclude that winter minimum seafloor temperature was similar to present values (typically 6–7 °C) in the adjacent so…
Hedging spark spread risk with futures
2018
Abstract This paper discusses the spark spread risk management using electricity and natural gas futures. We focus on three European markets in which the natural gas share in the fuel mix varies considerably: Germany, the United Kingdom, and the Netherlands. We find that spark spread returns are partially predictable, and consequently, the Ederington and Salas (2008) minimum variance hedging approach should be applied. Hedging the spark spread is more difficult than hedging electricity and natural gas price risks with individual futures contracts. Whereas spark spread risk reduction for monthly periods produces values of between 20.05% and 48.90%, electricity and natural gas individual hedg…
Spreading Depression Induces Permanent Cell Swelling Under Penumbra Conditions
2000
Background. Spreading depression (SD) is known to go along with temporary breakdown of ion gradients and cell swelling which spontaneously normalizes. Here, the effects of SD at reduced flow conditions as encountered in the ischemic penumbra are examined.