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Numerical Investigation on the Effects of Different Thermal Insulation Strategies for a Passenger Car Diesel Engine
No full textAbstractOne of the key technologies for the improvement of the diesel engine thermal efficiency is the reduction of the engine heat transfer through the thermal insulation of the combustion chamber. This paper presents a numerical investigation on the effects of the combustion chamber insulation on the heat transfer, thermal efficiency and exhaust temperatures of a 1.6 l passenger car, turbo-charged diesel engine. First, the complete insulation of the engine components, like pistons, liner, firedeck and valves, has been simulated. This analysis has showed that the piston is the component with the greatest potential for the in-cylinder heat transfer reduction and for Brake Specific Fuel Consumption (BSFC) reduction, followed by firedeck, liner and valves. Afterwards, the study has been focused on the impact of different piston Thermal Barrier Coatings (TBCs) on heat transfer, performance and wall temperatures. This analysis has been performed using a 1-D engine simulation code coupled with a lumped mass thermal model, representing the engine structure. A time-periodic wall conduction model has been used to calculate the wall temperature swings along the combustion chamber surface and within the engine cycle. Two different TBC materials, Yttria-Partially Stabilized Zirconia (Y-PSZ) and anodized aluminum, and different layer thicknesses have been simulated
3D spatially resolved models of the intracellular dynamics of the Hepatitis C genome replication cycle
No full textAssessment of the efficiency of seismic design for structural robustness of rc structures
No full textStructural robustness is the ability of a structure to resist against progressive and/or disproportionate collapse. Although at present the main structural regulations foresee guidance for robustness, often the designers don't consider directly these requirements; however, in some cases the buildings have been designed to withstand earthquakes, following the capacity design criteria. The aim of this work is to assess the efficiency of the seismic detailing to ensure robustness of structures not directly designed against progressive and disproportionate collapse. The assessment is based on the comparison of two distinct design of the same structure: in the first case the seismic action is considered, while in the second one the seismic action is neglected. Both the structures are subjected to a column removal and their response after this exceptional event is evaluated. Three different configurations are tested removing respectively an internal, an edge and a corner column placed at the ground floor level. The obtained results show the improvement achievable, in terms of structural robustness, adopting seismic detailing, highlighting the importance of a seismicoriented design also in the prevention of collapse due to accidental actions
Influence of block copolymer feature size on reactive ion etching pattern transfer into silicon
No full textDeposition of polycrystalline and nanocrystalline diamond on graphite: effects of surface pre-treatments
No full textNumerical Simulation of Failure in Fiber Reinforced Composites
No full textThis paper presents numerical results concerning the failure analysis of fiber-reinforced composites. In particular, damage initiation and progressive failure are considered. The numerical framework is based on the CUF advanced structural models and the component-wise approach. Such models are employed at all scales. In other words, the same structural framework is employed for macro-, meso-, and microscales. Two approaches are assessed, including direct numerical simulations via micromechanical homogenization analysis and two-scale analysis. The results are compared with those from literature and attention is paid to the evaluation of the computational efficiency of the present numerical framework. In fact, 3D-like accuracy is sought with a reduced computational effort
LEFT VENTRICULAR UNLOADING DURING PERIPHERAL EXTRACORPOREAL MEMBRANE OXYGENATOR SUPPORT (ECMO): A BRIDGE TO LIFE IN PROFOUND CARDIOGENIC SHOCK
No full textAbstract Background A limit of peripheral veno-arterial Extracorporeal Membrane Oxigenator (VA-ECMO) is the inadequate unloading of the left ventricle. The increase of end-diastolic pressure reduces the possibility of a recovery and may cause severe pulmonary edema. In this study, we evaluate our results after implantation of VA-ECMO and Transapical Left Ventricular Vent (TLVV) as a bridge to recovery, heart transplantation or long- term left ventricular assit devices (LVAD). Methods and Patients From 2011 to 2014, 24 consecutive patients with profound cardiogenic shock were supported by peripheral VA-ECMO as bridge to decision. In all cases, TLVV was implanted after a mean period of 12.2± 3.4 hours through a left mini-thoracotomy and connected to the venous inflow line of the VA-ECMO. Results Thirty-day mortality was 37.5% (9/24). In all patients, hemodynamics improved after TLVV implantation with an increased cardiac output, mixed venous saturation and a significant reduced heart filling pressures (p< 0.05). Recovery of the cardiac function was observed in 11 patients (11/24; 45.8%). Three patients were transplanted (3/24; 12.5%) and 3 patients (3/24; 12.5%) underwent LVAD implantation as destination therapy, all these patients were discharged from the hospital in good clinical conditions. Conclusions In these critical patients, systematic TLVV improved hemodynamic seemed to provide better in hospital survival and chance of recovery, compared to V-A ECMO results in the treatment of cardiogenic shock reported in the literature . TLVV is a viable alternative to standard VA- ECMO in order to identify the appropriate long-term strategy (heart transplantation or long-term VAD
Cryocooled programmable and pulse-driven Josephson voltage standards at INRiM
No full textIn the last decades, voltage metrology research has been mainly directed towards the application of arrays of Josephson junctions for the synthesis of quantum-based ac and arbitrary voltage waveforms. Currently, ac voltage calibrations are performed with conventional calorimetric methods based on ac-dc transfer standards, but they are not intrinsically accurate. Programmable and pulse-driven Josephson arrays represent the two more common ways for linking ac voltage calibrations to a quantum phenomenon. Moreover, in order to allow the spread of Josephson standards in many industries and laboratories, a user-friendly and safe refrigeration system is preferable: cryocoolers satisfy these needs. In this work, we present our cryocooler system for the operation of ac Josephson voltage standards. We synthesized sine waves at different amplitudes in the kHz range with both programmable and pulsed standards. In order to guarantee a proper operation, optimal thermalization of the Josephson chip is required and interventions aimed at this goal are presented here
A New Resilience Rating System for Countries and States
No full textThis research presents a quantitative method to assess resilience at the state level. The approach introduced in this work is an evolution of the risk assessment concept. Risk is mainly a function of vulnerability, hazard, and exposure; on the other hand, resilience focuses more on the internal characteristics of a system rather than its vulnerability. To tackle this difference, a new formulation has been introduced for the evaluation of resilience. In this formulation, resilience is a function of hazard, exposure, and intrinsic resilience. Generally, intrinsic resilience deals with the internal characteristics of a system, and it differs from the traditional resilience index that takes into account external factors in its assessment, such as the disaster intensity and the level of exposure. The paper also provides a method to compute the intrinsic resilience of countries. This method is based on the data provided by Hyogo Framework for Action (HFA), which is a work developed by the United Nations (UN). HFA evaluates the inherent resilience of countries based on a number of equally weighted indicators. However, further analysis has shown that the contribution made by each of those indicators toward the intrinsic resilience is different. This discrepancy has necessitated weighting the indicators based on their individual contribution towards the intrinsic resilience. To do that, we introduce the Dependence Tree Analysis (DTA). DTA is a method that determines the correlation between a component and its sub-components (i.e., between intrinsic resilience and its indicators), enabling us to orderly allocate new weights to the indicators to obtain a more representative output for the intrinsic resilience. Finally, a case study composed of 37 states has been conducted in order to illustrate the methodology in all details. Both intrinsic resilience and resilience indexes for each of the states were assessed. This was followed by a comparative analysis in order to test the applicability of the methodology, and the results were in line with the predictions
