1,324 research outputs found
Experimental Analysis, Modeling and Control of Volumetric Radial-Piston Pumps
No full textAn experimental-theoretical study has been carried out on high-pressure volumetric radial-piston pumps for diesel fuel injection systems. The dependence of the pump inducted flow rate on speed and load was investigated and the characteristic curve of the pump cooling-lubrication circuit was derived. The head-capacity curves were determined for different types of pumps at different revolution speeds and compared with the injector flow requirements in order to evaluate the pressure-control strategy efficiency. An insight into the ageing effects on the pump performance was also provided. Furthermore, the dynamic pump behavior was investigated, with specific reference to the flow-rate ripple at the delivery port. A general analytical expression has been derived for the volumetric efficiency. Furthermore, a specific procedure has been developed and applied to the experimental evaluation of the fuel leakages in pressure control valve (PCV) integrated pumps. Finally, the mechanical-hydraulic efficiency of the pump has experimentally been assessed as a function of head and speed in order to obtain a reliable evaluation of the pump shaft power and torque at different working condition
Further Development and Experimental Analysis of a New Common Rail Fuel Injection System without Accumulator
No full textAn innovative hydraulic layout for Common Rail (CR) fuel injection systems (FIS) without accumulator was further developed and assessed. The rail was removed and replaced by a high-pressure pipe junction to have faster dynamic system response during engine transients, smaller pressure induced stresses and reduced production costs. Compared to a commercial rail, whose internal volume ranges from 20 to 40 cm3 , the junction provided a hydraulic capacitance of about 2 cm3 with the main function of connecting the pump delivery to the electroinjector feeding pipes. The modified injection system was realized and subjected to experimentation under engine-like working conditions on a high performance Moehwald-Bosch test bench. The injection performance of the new system with different hydraulic layouts was shown to be generally similar to those of a commercial CR system. Besides, for multiple injections, the new layout dynamics were substantially improved by a reduced dependence of the overall injected fuel amount on dwell-time (DT) during sequential injection events. This was achieved by selecting injector supplying pipes with an internal diameter and length out of the present production range. The results supported the findings that the rail capacitance was not a key parameter in pressure wave disturbance attenuatio
Flexible Multibody System Dynamics by Means of a Spectral Based Meshless Approach
No full textIt is a common practice in industry to model the elasticity in flexible multibody dynamics, when the deformations are small, by means of a linear finite element approach and of a model condensation strategy. Taking into account the flexibility in multibody modelling may require computationally expensive numerical models to be managed. Proper shape functions are introduced in this paper to model the displacements of flexible slender beam components, without the need of any spatial discretization; a novel formulation of the flexible properties of beam-like components follows and a small size motion equation set can be obtained. Modelling aspects, from point location to constraint equations and to elastodynamic modelling, are discussed. An ideal quick return mechanism, properly actuated, is modelled as a test case to prove the effectiveness of the proposed approach
Development and assessment of a new operating principle for the measurement of unsteady flow rates in high-pressure pipelines
No full textInstantaneous mass flow rate measurements in high-pressure transmission pipelines under transient flow conditions can be valuable for the analysis of hydraulic power systems. However, at present no reliable commercial measuring device is available for pressure levels beyond 300 bar. A new operating principle, of general application, for measuring the flow rate in high pressure flows (from 300 to 2000 bar) was developed and assessed. The innovative device was capable of accurately evaluating the instantaneous mass flow rate on the basis of the pressure time-histories detected at two different locations by high pressure transducers. The measurement operating principle was detailed and technical indications for the flowmeter correct design were provided. For validation purposes, the flow rate measurements taken at the inlet of a Multijet Common Rail (CR) injector were compared to the theoretical data predicted by an ad-vanced numerical model of the complete fuel injection system. The developed flowmeter was then applied to characterize the flow rate ripple at the delivery of the CR high-pressure reciprocating pum
La relazione dell’Ispettore Alessandro Parone sullo stato dell’istruzione primaria nel circondario di Siracusa (1864)
No full textIl presente contributo di ricerca intende approfondire lo stato dell’istruzione elementare del Circondario di Siracusa, all’indomani dell’unificazione del Regno d’Italia, quando l’ordinamento scolastico previsto dal Casati, attraverso il decreto Mordini del 17 ottobre 1860, venne esteso in Sicilia. Oggetto di studio particolareggiato di questa ricerca sarà la dettagliata relazione dell’Ispettore circondariale Alessandro Parone, una fonte inedita dalla cui analisi è possibile trarre interessanti informazioni sul reale andamento dell’istruzione primaria nei comuni e nelle borgate del Circondario di Siracusa, nell’arco temporale compreso tra il novembre del 1862 e l’agosto del 1864. This research intends to deepen the state of elementary education in the Syracuse district, after the unification of the Kingdom of Italy, when the school system envisaged by Casati, through the Mordini decree of 17 October 1860, was extended in Sicily. The subject of detailed study of this research will be the detailed report of the District Inspector Alessandro Parone, an unpublished source from whose analysis it is possible to draw interesting information on the real trend of primary education in the municipalities and villages of the Syracuse district, over the period of time. between November 1862 and August 1864
A Condensation Technique for Finite Element Dynamic Analysis Using Fractional Derivative Viscoelastic Models
No full textFractional derivative rheological models are known to be very useful for describing the viscoelastic behaviour of materials, especially of polymers, and when applied to dynamic problems, the resulting equations of motion, after a fractional state-space expansion, can still be studied in terms of modal analysis. The increase in matrix dimensions produced by this expansion, however, is often so fast as to make the calculations too cumbersome for finite element applications. This article presents a condensation technique based on the computation of two reduced-size eigenproblems. The rheological model adopted is the fractional Zener (fractional standard linear solid) model, but the same methodology can be applied to problems using different fractional derivative linear model
Metodo per determinare la portata istantanea di un fluido, particolarmente per un liquido in una condizione di alta pressione.
No full textDigital TV as Monitoring System for Elderly People Health Care
No full textThe aim of the paper is to describe a project concerned with the development of a daily monitoring system for elderly people living alone. The system relies on a new non invasive type of communication based on devices commonly owned by elderly people, to reduce initial cost of deployment. All collected data could then be analyzed by a Medical Doctor to monitor the real current situation of the patient using open source instrument to generate analysis, report and data mining tasks
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