196,219 research outputs found
UAV trajectory control with rule-based minimum-energy reference generation
No full textThis paper deals with the hierarchical real-time control of unmanned aerial vehicles (UAVs) with rule-based strategy for mission time and energetic references generator based on optimal control theory. The objective of this work is to design a control which ensures an energy consumption close to the optimality, and easily implementable thanks to its low computational cost. The first part of the work deals with the extraction of simple and immediate rules for the determination of the optimal mission time, and the generation of 'energetic trajectories' from the analysis of the optimal control strategy results, to minimize the consumption over a high heterogeneous amount of simulations. Then, a hierarchical real-time controller is proposed to track desired energetic trajectories, identified as optimal. The results provided are validated through numerical experiments and compared in terms of energy performance with the optimal solution
Acoustical reconstruction of San Petronio Basilica in Bologna during the Baroque period: the effect of festive decorations
No full textThe Basilica of San Petronio in Bologna (Italy) is a large Gothic church characterized by three naves divided by cluster piers made of brick and flanked by square chapels. It is 130 m long, 60 m wide and 44 m high, developing a volume of 170000 m3. The widespread use of smooth plaster and the substantial lack of decoration give rise to a reverberation time (in unoccupied conditions) which varies from about 13 s at 125 Hz to 5 s at 4 kHz, with an average of 10.7 s at mid frequencies. In occupied conditions the expected mid-frequency reverberation time should lower to about 6.5 s. Nonetheless, these acoustic conditions appear scarcely compatible with the characteristics of the Baroque music which was composed for the "Cappella musicale" during the 17th century. However, historical research pointed out how, in that period, rich draping and curtains were often used during the major religious and civil celebrations. The analysis of the acoustic consequences of such temporary installations was performed by means of acoustic simulation based on historical records calibrated on the current configuration of the church. The paper presents the results of such reconstructio
Effect of Vacuum or Modified Atmosphere Packaging on Some Beef Quality Characteristics
No full textNowadays, beef shelf-life is very important in relation to various marketing methods that tend to prolong the duration of this product. For this reason, it is interesting to study the effect of different packaging methods on several meat quality parameters. Five steaks were taken from each half-carcass derived from six female veal calves, after 7 days of aging. In each group, one steak was analysed unpackaged, two steaks were vacuum-packed and conserved for 7 and 14 days respectively, while the last two steaks were packaged in a modified atmosphere (60% O2, 30% CO2, 10% N2) and conserved for 7 and 14 days respectively. Thus, meat was analysed for pH, colour, measured on the surface and inside, and water-holding capacity was expressed as Meat/ Total ratio. Results showed that pH values were normal and tended to be constant independent of packaging method and length of conservation. The colour parameters measured on the surface of the meat confirm that the vacuum-packaged method induces a slight darkening of the meat (significantly lower values of b* and H*) after both 7 and 14 days of storage. Nevertheless, internal meat colour and water-holding capacity are similar for the two packaging systems, independent of the length of storage. These results, along with the findings of a previous study that testify to the higher microbiological stability of vacuum-packaged meat, lead us to conclude that although the appearance is less attractive, this method permits longer meat storage
Detection of Mycobacterium avium subsp. paratuberculosis in ovine intestine: correlations between histological lesions, mycobacterial staining and immunohistochemical findings.
No full textEffetto della dieta materna sulla composizione acidica della carne dell'agnello da latte
No full textEffect of Islamic ritual slaughter on beef quality
No full textThe aim of this study was to evaluate several quality characteristics of meat obtained from 20 Limousine calves slaughtered either according to conventional methods (n=10) or by the Islamic ritual slaughtering procedure (n=10). After 7 days of ageing under vacuum, pH, drip loss, colour and oxymyoglobin percentage were measured on longissimus dorsi muscle after 2h, 2 and 6 days of storage to study their evolution. With conventional slaughter pH remained stable until the 6 th day of storage, while with ritual slaughter it increased from the 2 nd to 6 th day of storage. Drip loss increased considerably from the 2 nd to 6 th day of storage in conventional slaughter, while in ritual slaughter the drip loss increase was lower. Meat colour was not influenced by the slaughtering system but only by the different lengths of storage
Shelf-life determination of organic Chianina meat vacuum-packed
No full textMaintaining quality and appearance is essential during the distribution
and merchandising of meat, for this reason packaging has
become an indispensable method to control organoleptic and
chemical changes and to increase the shelf-life of this product.
The aim of the trial was to test the shelf-life of meat derived from
Chianina cattle reared under organic system and stored under vacuum
packaging (VP). This trial was carried out on 8 Chianina
females, slaughtered at 22 months of age; after one week of ageing,
from each right half carcass 4 longissimus dorsi samples were
taken: 1 sample was overwrapped with a traditional packaging
(fresh meat) and 3 were stored under VP for 7, 14 and 21 days. To
evaluate the effect of VP on qualitative parameters of beef, the following
analyses were performed: pH, drip loss (%), cooking loss
(%), tenderness (shear force kg), colour (L*a*b*C H), oxymyoglobin
(%) and lipid oxidation (mg MDA/kg meat). Analyses were carried
out on 32 samples: 8 before storage (fresh meat), 8 after 7
days of storage in VP, 8 after 14 days of storage in VP and 8 after
21 days of storage in VP. All data were analyzed by least squares
means considering as categorical variable the storage time. Meat
pH and water holding capacity were not affected by VP and values
tended to be stable until 21 days. Meat tenderness increased significantly
during storage time (P<0.05), as a consequence of carrying-
on of the meat ageing in VP. As regard meat colour, L* value
was not significantly influenced by VP, whereas a*, b*, C and H values
showed discoloration in meat under VP (P<0.01), probably
because the myoglobin changed in oxidized form, metmyoglobin,
as confirmed by the significantly decrease of oxymyoglobin
(P<0.01). Moreover the storage time didn’t show significant effect
on lipid oxidation of meat under VP. Therefore, the meat stored
under VP showed some modifications in tenderness and colour in
comparison with fresh meat, but from 7 to 21 days all parameters
appeared to be stable over time, showing the good shelf-life of the
Chianina meat obtained with organic system
Strategy for the detection and differentiation of Mycobacterium avium species in isolates and heavily infected tissues.
No full textThe members of Mycobacterium avium species, comprising M. avium subsp. paratuberculosis, M. a. hominissuis, M. a. avium, M. a. silvaticum, are currently the most prevalent opportunistic pathogenic mycobacteria causing mycobacterial infection in animals and humans. The ability to distinguish between these subspecies is of relevance for proper diagnosis and control programmes of the diseases.
The aim of this study was to design a fast and specific PCR strategy for the detection and differentiation of M. avium subspecies from the solid plate cultures for use in routine veterinary diagnosis. We have developed a multiplex PCR based on IS900, IS901, IS1245 and the dnaJ gene. This method allows the detection of M. a. paratuberculosis, M. a. hominissuis and M. a. avium/M. a. silvaticum in one PCR
reaction and theoretically enables mixed infections of M. a. paratuberculosis and M. a. avium or M. a. paratuberculosis and M. a. hominissuis to be revealed. The sensitivity of this multiplex PCR is 103 CFU for each bacterial strain in one PCR reaction, which also enabled the use of this test directly for DNA isolated from the tissue of the heavily infected sheep
Quality of carcass and meat in bullock of different genotypes raised under organic system
No full textCarcass and meat quality of three muscles from 17 Limousine and 17 Limousine x Red Pied organically-raised beef cattle were studied. The carcasses were classified according to the European (S)EUROP classification scale and some linear measurements were taken. After an 8-day ageing period, longissimus thoracis, triceps brachii and semitendinosus muscles were excised from all carcasses and subjected to the following analyses: pH, meat colour, water holding capacity, tenderness, chemical composition and fatty acid profile. The carcasses deriving from the two genetic types were of medium conformation and had a slight fattening degree; the Limousine bullocks produced meat which was lighter and paler in colour, more tender and with a lower percentage of intramuscular fat. Comparison between muscles showed that
the semitendinosus had higher values of Lightness (L*) and Hue (H*), thus giving lighter and paler meat, but it was less tender and had a higher cooking loss. Meat quality characteristics of triceps brachii and longissimus thoracis muscles were similar; the meat analysed had a very
low content of intramuscular fat, expressed as ether extract. Only slight differences between muscles were found in the fatty-acid profile
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