1,721,057 research outputs found
On-line model-based wheel speed filtering for geometrical error compensation
No full textWheel speed measurements provided by incremental encoders in road vehicles are usually affected by a significant periodic noise. Unavoidable geometrical or misalignment errors in the structure of the encoder are here regarded as possible causes of the measurement disturbance. Such disturbances are commonly rejected using simple solutions, like low-pass or notch filters. However, such methods may not be adequate in some applications, as the signal information is canceled jointly with the disturbances, thus jeopardizing the overall system performance. This paper presents an online filtering procedure, based on the geometrical model of the sensor and recursive constrained least squares estimation, aimed at rejecting only the periodic noise. Such a procedure will result into a speed measurement processing that is most suited for advanced vehicle applications. Experimental data are used to show the effectiveness of the proposed approach considering two different vehicles: a bicycle - where the proposed method is shown to be effective for cycling cadence estimation - and a sport car - where the speed variable is of primary importance, e.g., for braking and stability control
CRISPR -Cas9: a groundbreaking new technique which ushers in new prospects and just as many doubts
Full text linkHuman germline engineering arguably constitutes one of the most promising and at the same time controversial prospects in the realm of gene editing overall, and particularly in the context of the current state of research. The issues raised by such techniques have sparked heated debate worldwide: the scientific and industrial establishments have been strongly supporting CRISPR-Cas9 research, but a well-balanced approach needs to be adopted in order to reconcile the needs of scientific research with the life and dignity of human embryos
ASSESSING FAO-56 MODEL TO ESTIMATE TABLE OLIVE WATER CONSUME UNDER SOIL WATER DEFICIT CONDITIONS
No full textAgro-hydrological models can be considered an economic and simple tool to quantify crop water requirements. In the last two decades, agro-hydrological physically based models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere system. Although very reliable, due to the high number of required variables, simplified models have been proposed as simple tools to quantify crop water consumes.
The main aim of the paper is to assess, for a Sicilian orchard of table olive, the suitability of FAO-56 agro-hydrological model to estimate the crop transpiration under soil water deficit conditions. The model validation is carried out by means of measurements of sap-flow and soil water contents, acquired during three years of field observations. An amendment of the model is suggested in order to take into account the water stress function and the soil water uptake ability as experimentally evaluated.
The results show that the modified model improves the estimation of crop transpiration and soil water content, considered that the associated RMSEs resulted higher than the corresponding values obtained with the original version of the model
Discussion of "modeling Approaches for Determining Appropriate Depth of Subsurface Drip Irrigation Tubing in Alfalfa" by Rocio Guadalupe Reyes-Esteves and Donald C. Slack
No full textData-driven clamping force control for an Electric Parking Brake without speed measurement
No full textThis paper addresses the control of the clamping force provided by an Electric Parking Brake (EPB). A simple on-off strategy is implemented: the device is actuated until the actual force reaches the target value maintaining the vehicle in a steady position. The effectiveness of the control is then highly depending on the quality of the clamping force estimation. The proposed estimator relies on the sole DC motor current and voltage signals and does not require the knowledge of any physical parameters nor the measurement of the DC motor angular displacement. Extensive eperimental tests show the robustness of the proposed strategy with respect to different operating and aging conditions
Modelling eco-physiological response of table olive trees (Olea europaea L.) to soil water deficit conditions
No full textThe knowledge of crop response to water stress is crucial to predict transpiration reductions under limited soil water conditions and for a rational scheduling of irrigation.
In order to assess whatever water stress model, it is necessary to estimate critical thresholds of soil water status, below which plant transpiration starts to decrease.
The main objective of the work is to identify the shape and to determine the parameters of table olive orchards (Olea europaea, var. Nocellara del Belice) water stress function, assessed according to relative transpiration or leaf/stem water potential.
In order to assess different water stress functions describing the eco-physiological field response to soil water status, an experimental campaign was carried out in a farm located in South-West coast of Sicily. Meteorological data and soil and crop water status were monitored during irrigation seasons 2008 and 2009.
A value of soil matric potential of about −40 m was identified as the threshold below which actual transpiration decreases with decreasing soil water content. For values of soil matric potential higher than the critical threshold, actual transpiration resulted almost constant. A similar behavior was observed when the xylematic leaf/stem water potentials were used to quantify the crop water stress. Investigation also showed that the non-linear models better reproduced the initial phase of the transpiration reduction process; for the examined crop, in fact, convex shape models, typical of xerophytes, better reproduce the reductions of actual transpiration under the soil water deficit conditions recognized in the field
Indirect estimation of calibration equation parameters for Sentek Diviner 2000 capacitance probe by means of soil physical properties
Full text linkMeasurements of soil water content (SWC) are often used for irrigation scheduling. Accurate monitoring of SWC is
necessary, for example, to identify the exact irrigation timing and the amount of water volume to supply according
to the crop requirement.
The use of capacitance probes, measuring the apparent soil dielectric permittivity, indirectly related to soil water
status, have been increasing during the last decade, as proved by the numerous researches carried out to determine,
for different soil types, site-specific calibration relationships between SWC and the scaled frequency (SF) measured
by the sensor. However, for swelling/shrinking clay soils, there is a lack of knowledge on how the changes of
soil bulk density associated to variations of soil water content influence the apparent dielectric permittivity and
therefore the sensor calibration relationship, as a consequence of the different contribute that soil, water and air,
have on the measure provided by the sensor.
The main objectives of the work are i) to determine the site specific calibration equations for a Sentek Diviner 2000
capacitance probe for soils characterized by different texture, ii) to investigate on the effects of soil bulk density
and its variability with soil water content, on the calibration equation and iii) to proceed to the indirect estimation
of calibration parameters by means of easily-measurable soil physical properties.
Experiments were carried out on nine different soils collected from Sicilian irrigated area, characterized by a clay
percentage ranging between 9% and 45%. Undisturbed soil samples (25 cm diameter and 25 cm height), allowed to
determine, for each soil, the corresponding site-specific calibration equation. On the other hands, samples having
the same dimensions, but filled with sieved soil and compacted at two different bulk densities ( b), were used
to investigate on the effects of soil texture and bulk density on the measured SF. On each undisturbed or sieved
sample and for all the investigated soils, the shrinkage characteristic curve, b(U) and the U(SF) relationship were
contextually determined.
The experiments on sieved soil samples, allowed to verify that the scaled frequency measured by the sensor also
depends on b. According to this result, the generally used calibration equation was modified and a new empirical
model U(SF, b), introducing the relationship b(U) as a factor, was proposed. Of course, for swelling/shrinkage
clay soil the suggested calibration equation results implicit, if considering that b is also a function of U.
The experiments also allowed to verify that parameters of the calibration equation depend on soil clay percentage
and then to identify empirical relationships for their estimation, that were finally validated by using measurements
acquired on undisturbed soil samples and some data collected by the literature
In tema di lavoro usurante: alcune considerazioni.
No full textGli Autori presentano le principali cause della usura dell'organismo e le misure di prevenzione, dando la possibilità di un uso proficuo delle capacità effettive di lavoro dei singoliThe authors present the main causes of wear of the organism and prevention measures, giving the possibility of a beneficial use of the actual working capacity of the individua
Agro-hydrological models to schedule irrigation of Mediterranean tree crops
No full textIn this paper a comparison between two agro-hydrological models, used to schedule irrigation of typical Mediterranean tree crops, is assessed. In particular the comparison between the model proposed by FAO, using a black box processes schematization, and the SWAP model based on the numerical analysis of Richards’ equation is initially presented for two irrigation seasons, 2005 and 2006, and two Mediterranean tree crops, i.e. grapevine (Vitis vinifera, L.) and olive oil (Olea europea, L.). The comparison mainly focuses on hydrological balance components and on soil
water contents.
After investigating and setting the scheduling parameters ordinarily practiced by the framers in the area (i.e ordinary management), the performance of the two models aimed to evaluate seasonal water requirement and irrigation time, is assessed.
In the validation phase both the models satisfactorily simulated the soil water content, allowing to obtain quite comparable values of evapotraspiration fluxes. On the other hand, when the models are used for scheduling irrigation, the FAO 56 model usually overestimates the irrigation amount, as a result of an overestimation of the transpiration fluxes. On the contrary the SWAP model simulates values of crops water requirements and a number of irrigation corresponding to those evaluated in the ordinary scheduling at the investigated area. Finally, in order to improve the FAO 56 model performance, a modification of the stress function is presented and discussed
Comment on the article by Zaami et al "Increasing abuse of anabolic steroids and chemsex drugs as performance and image-enhancing agents". Eur Rev Med Pharmacol Sci 2021; 25: 455-458
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