1,721,089 research outputs found
Dal recupero edilizio e urbanistico alla riorganizzazione delle strutture insediative
No full textIl confronto tra recupero urbano e sviluppo delle strutture insediative, in base a ricerche empiriche e quantitative su dati censuari e indagine dirett
NUMERICAL ANALYSIS AND EXPERIMENTAL INVESTIGATION OF A COMMON RAIL TYPE DIESEL INJECTOR
No full textA production common rail-type injector has been investigated via numerical simulation and experimentation. The functioning principle of the injector has been carefully analyzed so as to obtain a mathematical model of the device. A zero-dimensional approach has been used for modeling the injector, thus considering the variables as function of time only. The analysis of the hydraulic part of the injector resulted in the definition of an equivalent hydraulic scheme, on which basis both the equations of continuity in chambers and flow through nozzles were written. The connecting pipe between common rail and injector, as well as the injector internal line, were modeled according to a onedimensional approach. The moving mechanical components of the injector, such as needle, pressure rod, and control valve have been modeled using the mass-spring-damper scheme, thus obtaining the equation governing their motion. An electromagnetic model of the control valve solenoid has also been realized, in order to work out the attraction force on the anchor, generated by the electric current when flowing into its coil. The model obtained has been implemented using the MATLAB® toolbox SIMULINK®; the ordinary differential equations were solved by means of an implicit scheme of the second-order accuracy, suitable for problems with high level of stiffness, while the partial differential equations were integrated using the finite-difference Lax-Friedrichs method. The experimental investigation on the common-rail injection system was performed on a test bench at some standard test conditions. Electric current flowing through the injector coil, oil pressure in the common rail and at the injector inlet, injection rate, needle lift, and control valve lift were gauged and recorded during several injection phases. The mean reflux-flow rate and the mean quantity of fuel injected per stroke were also measured. Temperature and pressure of the feeding oil as well as pressure in the rail were continuously controlled during the experimental test. The numerical and experimental results were compared. Afterwards, the model was used to investigate the effect of control volume feeding and discharge holes and of their inlet fillet, as well as the effect of the control volume capacity, on the injector performance
Il contratto di rete e la gestione delle risorse umane. Inquadramento normativo del fenomeno
No full textIl 2018 è stato definito da più parti l’anno del ritorno alla terra da parte dei giovani.
L’Italia, con quasi 55mila aziende agricole giovanili, è, infatti, il primo Paese in Europa
per la presenza di giovani agricoltori sotto i trentacinque anni. Tra il 2016 e il 2017 si è
riscontrato un aumento del 6% dei cosiddetti Millennial farmers.
I giovani non sembrano spaventati dalle problematiche operative e gestionali
dell’agroalimentare, che unisce le peculiarità dell’economia del settore primario – di
complicata razionalizzazione – alle più consuete logiche di mercato del mondo industriale.
In questo scenario nasce il Convegno Nazionale dell’Unione Giovani Dottori Commercialisti
ed Esperti Contabili che si terrà a Foggia dal 4 al 5 ottobre 2018, dal tema “Il
dottore commercialista attore nell’Agri-food italiano: analisi del business e strategie per la crescita”
A Linear Optical Sensor for Measuring Needle Displacement in Common-rail Diesel Injectors
No full textAlinear optical displacement sensorwas designed to overcome the problems related to the sensitivity of traditional transducers to electromagnetic disturbance, when applied to the measurement of needle lift in electrically actuated Diesel fuel injectors. The sensor consisted of a laser light emitter, a receiver, and a device used for modulating the intensity of the light reaching the receiver in function of position of the moving element. Thus, two rectangular windows were mounted on the injector body, while a third window was rigidly connected to the needle control piston, and aligned with the fixed ones, to obtain a clearance area which varied linearly with needle position. An optical fibre cable was used to transfer the laser light from the source to one of the fixed window, while a similar cable was connected between the second window and the receiver. Hence, the intensity of the light reaching the receiver was proportional to the position of the injector needle. Light intensity was converted into an equivalent voltage, and this signal was fed to the data acquisition system. The injector needle lift curves were measured and compared with those obtained with a commercial eddy current sensor. The reliability of the sensor was further improved by designing a suitable gasket that prevented fuel oil from reaching the optical windows, thus avoiding the onset of fluid cavitation, which would have resulted in bubble formation and consequent random laser light scattering, hence measurement alteratio
Optimal Management of Battery-Integrated Renewable Energy Communities for Providing Energy Flexibility Services
No full textThis paper examines the challenges and opportunities in the European energy sector, with a particular focus on Italy, in light of the ongoing energy crisis and policies aimed at transitioning to renewable sources. Utilizing an optimization-based approach, the study analyzes innovative methodologies to manage the complexities of the current energy system. Specifically, it investigates the crucial role of communication between distribution system operators and renewable energy communities in maximizing mutual benefits and addressing the challenges posed by the energy crisis. The findings of this study could provide valuable insights for the development of effective energy policies, guiding the transition towards a more sustainable and efficient energy system in Europe
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