1,720,975 research outputs found
Modeling of an Electromechanical Engine Valve Actuator Based on a Hybrid Analytical--FEM Approach
No full textThe use of an electromechanical valve actuator (EMVA) formed by two magnets and two balanced springs is a promising tool to implement innovative engine management strate- gies. This actuator needs to be properly controlled to reduce impact velocities during engine valve operations, but the use of a position sensor for each valve is not possible for cost reasons. It is therefore essential to find sensorless solutions based on increasingly predic- tive models of such a mechatronic actuator. To address this task, in this paper, we present an in-depth lumped parameter model of an EMVA based on a hybrid analytical–finite-element method (FEM) approach. The idea is to develop a model of EMVA embedding the well-known predictive behavior of FEM models. All FEM data are then fitted to a smooth curve that renders unknown magnetic quantities in analytical form. In this regard, we select a single- wise function that is able to describe global magnetic quantities as the flux linkage and force both for linear and saturation work- ing regions of the materials. The model intrinsically describes all mutual effects between two magnets. The goodness of the dynamic behavior of the model is finally tested on a series of transient FEM simulations of the actuator in different working conditions
Sulla utilità dell'ecografia nella diagnosi di alcune affezioni della cute e delo sottocutaneo
No full textElectro-hydraulic variable valve actuator and method to control valves of internal combustion engines
No full textDispositivo elettroidraulico di comando delle valvole di motori a combustione interna, ad azionamento variabile
No full textPancreatic cystosis in cystic fibrosis. Sometimes a bike ride can help you decide
Full text linkPancreatic cystosis (PC) is an uncommon manifestation of pancreas involvement in cystic fibrosis (CF), characterized by the presence of multiple macrocysts partially or completely replacing pancreas. Only few reports are available from literature and management (surgery vs follow up) is commonly based on the presence of symptoms or complications due to local mass effect, although evidence-based recommendations are still not available. We here report the case of a young adult CF patient with PC, in which cardiopulmonary exercise testing (CPET) provided important information to be integrated to the radiological finding of inferior vena cava compression by the multicystic pancreas complex. Through the analysis of oxygen kinetic cardiodynamic phase pattern, CPET may be helpful to safely exclude significant mass effects on blood venous return and to improve the decision-making process on whether to consider surgery or not in patients with PC
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Sistema e dispositivo elettroidraulico di comando delle valvole di motori a combustione interna ad azionamento variabile con unica elettrovalvola a tre vie
No full textDispositivo elettromeccanico di comando delle valvole di motori a combustione interna, ad azionamento variabile
No full textVariable-actuation, electro-hydraulic system and device controlling the valves of internal combustion engines
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