1,721,558 research outputs found
Esperienza didattica su un sistema idraulico: analisi del sistema e analogie con un circuito elettrico
No full textGli strumenti conservati presso l'antico laboratorio di fisica dell'Università di Urbino
No full textXXVI Congr. Nazion. AIF (Bellaria, 1987), i
POD approach for unsteady aerodynamic model updating
No full textA method for aerodynamic model updating is proposed in this paper. The approach is based upon a correction of the eigenvalues of the reduced order unsteady aerodynamic matrix through an optimization with objective function defined through the difference in the generalized aerodynamic forces or on the aeroelastic poles. The high fidelity model in reduced order form is obtained by the Proper Orthogonal Decomposition (POD) technique applied to the Computational Fluid Dynamics (CFD) Euler-based formulation. Many of the methods that have been developed in the past years for simpler aeroelastic models that use, for example, doublet-lattice method (DLM) aerodynamics, can be adopted for this purpose as well. However, this model is not able to capture shocks and flow separation in transonic flow. The proposed approach performs the updating of the aerodynamic model by imposing the minimization of a global error between target aerodynamic performances, namely, experimental performances, and an aerodynamic model in reduced order form via POD approach. After a general presentation of the application of the POD method to the linearized Euler equations, the optimization strategy is presented. First a simple test on a 2D wing section with theoretical biased data is performed and then the performances of different optimization strategies are tested on a 3D model updated by Wind Tunnel data
Effects of transparent polyethylene mulching and different planting densities on tomato grown for processing
No full textTomato cultivation is steadily increasing in the Sicilian countryside where careful management of clay soils alows successful yields. The crop is estabished in the first week of May an rainfall is adeguate to obtain a sufficient production without irrigation. In these areas a recent development in tomato production for processing is the use of transparent polyethylen mulching. The aim of this study was to verify the effects of transparent PE mulching vs. bare soil and of three different plant densities (0.74, 1.1 or 2.2 plants/m2) on a tomato crop in the Sicilian countryside. Applying PE mulch and planting at a density of 2.2 plants/m2 resulted in the highest yield (58.6 t/ha). The lowest production (15 t/ha) was obtained on bare soil and by planting at a density og 0.74 plants/m
Quality and shelf-life of minimally processed cauliflower
No full textIl cavolfiore è stato descritto come un ortaggio con un alto valore nutrizionale grazie al suo alto contenuto di vitamine, antiossidanti e composti anti-cancerogeni. Le infiorescenze di cavolfiore vengono raccolte mentre sono totalmente immature, il che implica gravi cambiamenti nello stato dei nutrienti, dell'acqua e degli ormoni. La raccolta e la successiva lavorazione possono causare gravi stress determinando la comparsa di sintomi di senescenza accelerata. Sono stati studiati gli effetti della lavorazione e della conservazione a freddo del cavolfiore trasformato minimamente. Gli ornamenti sono stati trattati con antiossidanti prima della conservazione in sacchi di PE a 4 ° C per 21 giorni. Durante il periodo di conservazione sono stati valutati perdita di peso, colore, compattezza, SSC e pH. Il cavolfiore ha mostrato una buona conservabilità e una manutenzione di qualità generale, ma anche una suscettibilità alla doratura delle zone di taglio.Cauliflower has been described as a vegetable with a high nutritional value due to its high content of vitamins, antioxidants and anti-carcinogenic compounds. Cauliflower inflorescences are harvested while they are totally immature, which implies severe changes in nutrient, water and hormonal status. Harvesting and the following processing can cause severe stress determining the appearance of accelerated senescence symptoms. The effects of processing and cold storage of minimally processed cauliflower were investigated. Florets were treated with antioxidants before storage in PE bags at 4°C for 21 days. During the storage period the weight loss, colour, firmness, SSC and pH were evaluated. Cauliflower showed a good shelf-life and overall quality maintenance but also a susceptibility to browning of cut zones
Use of plant growth-promoting rhizobacteria (PGPR) and organic fertilization for soilless cultivation of basil
No full textToday there is a greater environmental and ecological awareness and it is growing the number of farmers who want to adopt sustainable and efficient cultivation systems even if not officially certified as organic. Sustainable and modern cultivation systems must involve organic fertilization and cannot ignore the role of rhizosphere microorganisms. Starting from this premise, this paper aimed to evaluate the use of plant growth-promoting rhizobacteria (PGPR) and organic liquid fertilizers on soilless cultivation of basil. Genovese basil plants were cultivated in pots filled with a substrate inoculated or not with a commercial biostimulant (TNC BactorrS13) containing growth-promoting rhizobacteria (Bacillus spp.). Plants were fed only with water (control without fertilization) or with nutrient solutions (NS) that provided the same amount of nutrients with five combinations of mineral (M) and organic (O) fertilizers: 100 % M, 75 % M + 25 % O, 50 % M + 50 % O, 25 % M + 75 % O, 100 % O. The inoculum of the substrate with PGPR had no significant effect on basil plant growth but showed to be effective in decreasing the nitrate content of basil leaves. Several plant characteristics (e.g. yield, fresh and dry biomass, leaf number and area, stem diameter, etc.) showed to be negatively affected by the progressive reduction of the percentage of mineral fertilizer in the nutrient solution, in favor of the organic one, which, on the other hand, determined a significant reduction of the nitrate content of basil leaves
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