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Estimating aboveground biomass is important for monitoring crop growth in agronomic field experiments. Often this estimation is done manually, destructively (mowing) or not (counting) on a relatively limited number of sub-plots within an experiment. In the presence of spatial heterogeneity in experiment fields, sensors developed for precision agriculture, have shown great potential to automate this estimation efficiently and provide a spatially continuous measurement over an entire plot. This study investigated the suitability of using an unmanned aerial vehicle (UAV) for biomass and yield estimations in an agronomic field experiment. The main objectives of this work were to compare the estimates made from manual field sampling with those made from UAV data and finally to calculate the improvement that can be expected from the use of UAVs. A 6-ha maize field was studied, with plot treatments for the study of the exogenous organic matter (EOM) amendment effect on crop development. 3D surface models were created from high resolution UAV RGB imagery, before crop emergence and during crop development. The difference between both surface models resulted in crop height which was evaluated against 38 reference points with an R2 of 0.9 and prediction error of 0.16 m. Regression models were used to predict above-ground biomass and grain yield (fresh or dry). Dried grain yield prediction with a generalized additive model gave an error of 0.8 t ha−1 calculated on 100 in-field validation measurements, corresponding to a relative error of 14.77%. UAV-based yield estimates from dry biomass were 15% more accurate than manual yield estimation.

Electrical fast transients (EFT) represent an important problem to intravehicular networks. Concerning this problem, this paper reports a study about the impact of EFT to the performance of communication protocols used in intravehicular networks. A method of fast transient injection has been applied to an experimental CAN network with the objective of verifying the EFT impact on jitter and how it influences the communication process. An experiment with a simulated control system distributed over a real CAN network was carried out. For this experiment, an active suspension system was chosen as a case study and a sequence of EFT injections was performed. As a result, it was verified that injected EFT bursts increase jitter of safety-critical control messages and may effectively influence and produce faults during the communication process.

Made available in DSpace on 2019-10-06T16:20:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-04-15 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The mapping of the magnetic field and analysis of the plasma resistivity were used to study the change of magnetic field topology during the formation of a reversed field configuration. Using a theta pinch with straight coil, the formation of the torus was observed during the early time of the plasma radial implosion, in scale comparable to Alfvén’s time and shorter than the resistive diffusion. The non-intrusive excluded flux probe also indicated the formation of the torus even in the absence of mirror coils in the system. The plasma at the end region of the coil has distributed in the entire cross section of the tube, slightly peaked at the null field region. The anomalous plasma resistivity at the reconnection site was close to the prediction given by numerical calculation using numerical hybrid code with anomalous collision frequency either calculated using Chodura’s algorithm or evolution of microinstabilities, particularly the lower hybrid drift instability. Department of Physics and Chemistry Sao Paulo State University at Guaratingueta UNESP Department of Electrical Engineering Federal University of Sao Joao Del Rei Department of Physics and Chemistry Sao Paulo State University at Guaratingueta UNESP

A photogrammetric approach to characterize soil surface roughness is proposed.The measurement itself was reduced to the shooting of 13 overlapping photographs.The data processing has been fully automated into a python script.A system accuracy of 1.5mm has been determined on artificial models.96% of agricultural sites were well discriminated between 4 soil tillage levels. This work develops a fully automatic photogrammetric approach for measuring soil surface roughness from pictures taken in the field with a simple digital camera, without geometric constraints. On each site, 13 overlapping photographs of the soil surface were taken from different angles, under the shade of an umbrella. Millimeter accuracy 3D soil models were calculated from these pictures and were used to derive 11 roughness indexes. The whole procedure was implemented in a fully automatic Python program. The system accuracy was determined on artificial models built with polystyrene, the positional and elevation accuracies of which were about 1.5mm, while the error on the surface area estimation was less than 0.76% of the site surface area. This approach was successfully applied to an agricultural field experiment in which four soil tillage levels have been generated. These levels were correctly identified using two indices for 96% of the 32 measurement sites. These results show that two roughness indices, the surface tortuosity index and the mean value of height, are most efficient to discriminate agricultural soil tillage levels.

Spatially distributed systems which share communication resources have advantages such as lower implementation cost, better flexibility and reliability. When real-time distributed control applications make use of such architecture, the drawbacks are the networked-induced effects, which may severely degrade the controlled system performance. Efforts have been made by both communication and control communities to assess this problem: new control design techniques now consider explicitly the effects of these constraints, and some new communication protocols offer services to support the requirements from this kind of application. FlexRay is a protocol developed to support real-time safety-critical applications. In this study, a FlexRay network is built and an active suspension control is implemented in a distributed environment. The main goal is to analyse the impact the network-induced effects may bring to system performance.

Agronomic value and environmental impacts of three composts (a biowaste compost, BIO; a municipal solid waste compost, MSW and a compost made from green wastes co-composted with sewage sludge, GWS) are compared to those of farmyard manure (FYM) in a long-term field experiment located in Feucherolles (Yvelines, France) and initiated in 1998. The first compost spreading occurred in October 1998 and maize was sown in spring 1999.