1,721,376 research outputs found
Toxicological significance of biological markers - Significato tossicologico degli indicatori biologici
No full text
Development and Application of a Complete Multijet Common-Rail Injection-System Mathematical Model for Hydrodynamic Analysis and Diagnostics
No full textA rather complete mathematical model for a common-rail injection-system dynamics numerical simulation was developed to support experimentation, layout, and control design, as well as performance optimization. The thermofluid dynamics of the hydraulic-system components, including rail, connecting pipes, and injectors was modeled in conjunction with the solenoid-circuit electromagnetics and the mechanics of mobile elements. One-dimensional flow equations in conservation form were used to simulate wave propagation phenomena throughout the high-pressure connecting pipes, including the feeding pipe of the injector nozzle. In order to simulate the temperature variations due to the fuel compressibility, the energy equation was used in addition to mass conservation and momentum balance equations. Besides, the possible cavitation phenomenon effects on the mass flow rate through the injector bleed orifice and the nozzle holes were taken into account. A simple model of the electromagnetic driving circuit was used to predict the temporal distribution of the force acting on the pilot-valve anchor. It was based on the experimental time histories of the current through the solenoid and of the associated voltage that is provided by the electronic control unit to the solenoid. The numerical code was validated through the comparison of the prediction results with experimental data, that is, pressure, injected flow rate, and needle lift time histories, taken on a high performance test bench Moehwald-Bosch MEP2000-CA4000. The novel injection-system mathematical model was applied to the analysis of transient flows through the hydraulic circuit of a commercial multijet second-generation common-rail system, paying specific attention to the wave propagation phenomena, to their dependence on solenoid energizing time and rail pressure, as well as to their effects on system performance. In particular, an insight was also given into the model capability of accurately predicting the wave dynamics effects on the rate and mass of fuel injected when the dwell time between two consecutive injections is varie
Polineuropatia da collanti: prevalenza ed evoluzione della forma preclinica in due calzaturifici.
No full textAnalysis of the Impact of Electric Vehicle Penetration on Italian Electric Supply System
Full text linkElectric vehicles are progressively emerging in the light-duty passenger market as a promising alternative to oil-dependent road transport in the attempt to achieve greenhouse gas and pollutant emissions reduction. However, it is necessary to study in detail and to assess how a high penetration of electric vehicles in the private passenger vehicle fleet would affect strategic planning of large scale energy systems in the medium-long term period.
This study evaluates the integration of electric vehicles in the Italian energy scenario, assessing the impact on power generation capacity, energy consumption, CO2 emissions on a medium-long term perspective (up to 2030–2050), with the support of the EnergyPLAN software tool.
The national energy system has been accurately characterized using currently available data and its operation has been simulated with varying degrees of electric vehicle penetration through an integrated analysis method. The energy scenarios developed take into account realistic growth trends for variable renewable energy sources.
The results obtained assess the potential impact of electric vehicles in cutting transport carbon emissions and highlight potential sensible primary energy savings. Nevertheless, the analysis also reveals that an increase in electric vehicle penetration does not necessarily correlate directly to a growth in generation from renewable energy sources, because electric vehicle recharging strategies, and in particular the time of day when most vehicles are recharged, influence which power plants are mostly used to cover the additional electric energy needs
Sex hormones and liver cancer
No full textHepatocellular carcinoma (HCC) is one of the most common malignancy in the world and it usually occurs in individuals with chronic liver disease. The neoplasm is predominant in the male gender, where it is characterized also by a worst prognosis than in females. The pathogenesis of HCC is obscure. Because of its striking male predominance, androgens have been investigated as potential factors able to induce or at least promote hepatic carcinogenesis; this hypothesis has been also supported by the ability of androgens of inducing liver neoplasms in experimental models. On the other hand, due to the fact that HCC occurs predominantly in male cirrhotics who present a characteristic hormone imbalance with a relative hyperestrogenic state, the potential role of estrogen in liver cancer has been studied as well. In this paper, the potential role of sex hormones in liver carcinogenesis has been reviewed. (C) 2002 Published by Elsevier Science Ireland Ltd
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