263 research outputs found

    Comparative Analysis among DSP and FPGA-based Control Capabilities in PWM Power Converters

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    PWM power converters are close to be mature for standard diffusion. New FPGA technologies could now realise at best the digital control key-points: flexible performance and time to market. The paper deals with the new digital control properties of FPGA-based techniques. On the basis of reference structures, a comparative analysis is carried-out trading-off dynamic performances and immunity to PWM environment. All possible sampled control or DSP techniques are firstly analysed and compared to each other. A breakthrough concept for FPGAs is defined, definitely solving for PWM feedback immunity by practical over-sampling and parallel processing while improving dynamic performances. Simulation tests and the application of dead-beat control clearly point-out the respective dynamic properties

    Validation of an empirical model for grapevine leaf area estimation with data from the varieties ‘Cannonau’ and ‘Vermentino’ grown in Sardinia

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    The performance of two mathematical models for non-destructive estimation of primary and lateral leaf area per shoot of Tempranillo grapevines was tested in Sardinia using independent datasets from two main traditional varieties. One collected on Cannonau grapevines from Nurra wine region, and another from Vermentino grapevines grown in Gallura wine region. The models presented good fit between observed and estimated values with high modeling efficiency. For primary leaf area estimation the mean absolute percent error for both varieties was lower than 10%. Both linear regressions between observed and estimated primary leaf area had high and significant R2 but while Vermentino fitted line presented a slope not significantly different from 1, Cannonau fitted line showed a slope significantly < 1, indicating that the model overestimated the primary leaf area per shoot. The validation of the model for lateral leaf area presented lower goodness of fit as that reported for primary leaf area. Linear regressions had a very high and significant R2 but the slopes were significantly <1 indicating that the model overestimated lateral leaf area per shoot. The positive validation shows that these models can accurately predict leaf area per shoot independently of ecological conditions, variety, year, growth stage and training system. Low goodness of fit for lateral leaf area model may be avoided building the model on each variety data. The generalized use of this type of model represents a powerful tool for grapevine research, for consultants and advanced growers, allowing the evaluate vine leaf area more frequently and with low costinfo:eu-repo/semantics/publishedVersio

    Possible routes of animal exposure to cadmium and cadmium compounds and induced effects: a review

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    A retrospective analysis about cadmium and cadmium compounds teratogenicity, toxicity and carcinogenicity was carried out on literature basis, up to date, reviewed according to animal species, routes of exposure, acute and chronic response to different dosages via gastrointestinal or inhalatory uptake, target organs and apparatus. Some recent updates from experimental trials were also comparatively considered

    Preliminary Characterisation of Sardinian Red Grape Cultivars (Vitis vinifera L.) According to Their Phenolic Potential

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    Fourteen cultivars and clones, mainly selected from the island of Sardinia (Italy) and grown in a collection field,showed significant quantitative differences in phenolic potential. An extraction method designed to reproducethe winemaking process was used to determine the amounts of extractable polyphenols, anthocyanins, catechinsand proanthocyanidins reactive to vanillin, and the proanthocyanidins in grape skins and seeds. The Sardiniancultivar Nieddera and the Spanish cultivar Graciano had the highest concentrations of extractable polyphenols,anthocyanins, catechins and proanthocyanidins reactive to vanillin. Four clones of the Cannonau cultivar (synonymGrenache) exhibited fairly high variability, with significant differences in berry and seed phenolic contents

    Risposta allo stress idrico di alcuni portainnesti del ciliegio allevati in ambiente controllato

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    Growth chamber estimation under severe water-stress of behaviour of 4 cherry rootstocks (seedling, Colt, CAB/6 P and CAB/11 E) was carried out through the measure of leaf water potential, stomatal conductance and transpiration rates. This experience showed a positive correlation between leaf water potenti al and stomatal conductance, a difference equivalent to 1,0 - 1,5 M Pa, O,5 - O,7 . sec→1 and 15/h/m2 of water respectively in leaf water potential, stomatal conductance and transpiration rates between irrigated and stressed trees. In particular, CAB/6 P selection resulted the most sensible to water stress, followed by CAB/11 E, Colt and seedling; the last one kept more intense transpiration rates and showed more rapid restarting of stomatal conductance during recovery than Colt

    Gastro-intestinal parasites of pigs in Sardinia: a copromicroscopical investigation

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    This paper illustrates a copromicroscopical investigation carried out in Sardinia to update epidemiological data on diffusion of gastro-intestinal parasites in swine. Results obtained lead to suggest the employment of copromicroscopic exam to monitorate parasites diffusion in swine breedings in order to set up correct prophylactic and therapeutically intervents

    deficit irrigation strategies in vitis vinifera l cv cannonau under mediterranean climate part ii cluster microclimate and anthocyanin accumulation patterns

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    The contribution of light and thermal conditions to berry anthocyanin accumulation was investigated in grapevine Vitis vinifera L. cv. Cannonau/1103P subjected to different irrigation strategies in Sardinia, Italy in 2009. In two of the deficit irrigation treatments the root system received 50% and 25% crop evapotranspiration (ETc), referred to as DI50 and DI25, respectively. In the third treatment, which included partial root-zone drying (PRD), ETc was set at 50%. All three treatments were compared to a full irrigation control (FI), thus 100% ETc. Analysis of the thermal conditions during the growing season in 2009 provided evidence for a high frequency of elevated temperatures (> 30°C) during berry development. During ripening, the DI25 clusters intercepted significantly higher intensities (P < 0.01) of solar radiation, UV and PAR, particularly on the southeast canopy side, in comparison to FI and PRD. The analysis of berry temperatures in the DI treatments showed higher exposure to more than 35°C in the DI25 southeast berries. Thermal time for anthocyanin accumulation was computed for the DI50 and DI25 berries using normal heat hours (NHH). The patterns of daily NHH showed a reduction in thermal efficiency for anthocyanin accumulation during mid-ripening in the DI25 southeast berries compared to the DI50 ones. The higher temperatures at mid-ripening led to lower total anthocyanin contents in the DI25 berries. However, the coumaroyl-glucoside anthocyanin forms continued to increase in both the DI50 and DI25 berries, while a significant reduction in berry total contents of these forms was observed in FI and PRD. Both deficit irrigation and light conditions in the DI25 berries favoured the accumulation of more colourstable anthocyanins in the berry skin until harvest, namely p-coumaroyl-glucoside and acetyl-glucoside forms

    Stima evapotraspirativa dei fabbisogni irrigui nelle principali aree agricole della Sardegna

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    ETP calculation for three important irriguous areas of Southern (39°17' N. I), Central (39°53' N. I) and Northern (40°41' N. I) Sardinia through F.A.O. method shows too much high values with originai Blaney-Criddle equation, reduced differences with Penman (original and F.A.O.) equation, Radiation method and B.-C. F.A.O. equation respectively. The last method, believed the most suitable according to the first lisimetric measurements, estimates annual mean ETP equal to 1194 mm, 1077 mm and 1022 mm for Southern, Central and Northern Sardinia. Effective rainfall successive analysis shows they are 50% of total rainfall (in case of grasses) and they hold ETP for about 22%. Therefore seasonal irrigation requirements, calculated through F.A.O. crop coefficients, are among 841 mm, 791 mm and 706 mm concerning grasses, and 353 mm, 322 mm and 311 mm concerning olive tree, for Southern, Central and Northern Sardinia

    Some remarks on the use of TaqI to detect highly repetitive DNA sequences in human chromosomes

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    In the attempt to conclude investigation of the action of restriction endonucleases on eukaryote chromosomes, we carried out a series of experiments digesting in situ human metaphase chromosomes with AluI/TaqI followed by Giemsa staining. We focused on the centromeric regions of chromosomes1, 2 and 16 and noted that those areas appeared as intensely stained blocks after AluI digestion, but were dramatically reduced in size or completely destroyed after subsequent TaqI treatment. These results permitted us to draw some conclusions on the highly repetitive DNA composition of these regions, in terms of alphoid and classical satellite DNAs
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