Search results for "FLEX"
showing 10 items of 1677 documents
Spectral decomposition of cerebrovascular and cardiovascular interactions in patients prone to postural syncope and healthy controls.
2022
We present a framework for the linear parametric analysis of pairwise interactions in bivariate time series in the time and frequency domains, which allows the evaluation of total, causal and instantaneous interactions and connects time- and frequency-domain measures. The framework is applied to physiological time series to investigate the cerebrovascular regulation from the variability of mean cerebral blood flow velocity (CBFV) and mean arterial pressure (MAP), and the cardiovascular regulation from the variability of heart period (HP) and systolic arterial pressure (SAP). We analyze time series acquired at rest and during the early and late phase of head-up tilt in subjects developing or…
Effects of COVID19 pandemic on the Italian power system and possible countermeasures
2021
Abstract The paper analyses the dramatic effects of the first wave of the COVID-19 pandemic on the Italian power system, considering the impacts on load and generation, market issues and ancillary services provision. During the period between March and May 2020, the Italian scenario was considered as exemplary due to the large reduction of loads and thermal generation caused by the hard lockdown across the Country. Italy has experienced the most severe effects of pandemic in terms of increase of death rates and of pressure on the health system as well as severity of the countermeasures. As a domino effect, the total lockdown of one of the most industrialized countries in the world has creat…
Energy flexibility in Mediterranean buildings: a case-study in Sicily
2020
Since the building sector is responsible for 40% of the world’s electricity demand, it is essential to act on it in order to reduce emissions of climate change gases on a global scale, as expressed also in the latest directive on the energy performance of buildings. A design approach that focuses on the energy flexibility of buildings can contribute to the improvement of its energy-environmental performances. In this context, the objective of the study is the analysis of the energy performance of a residential building in Sicily and the definition of strategies aimed at increasing its energy flexibility. In particular, the case study is a 631 m2 single-family house, modeled and simulated in…
Strength and ductility of RC jacketed columns: A simplified analytical method
2016
Abstract Reinforced concrete (RC) jacketing is a common method for retrofitting existing columns with poor structural performance. It can be applied in two different ways: if the continuity of the jacket is ensured, the axial load of the column can be transferred to the jacket, which will be directly loaded; conversely, if no continuity is provided, the jacket will induce only confinement action. In both cases the strength and ductility evaluation is rather complex, due to the different physical phenomena included, such as confinement, core–jacket composite action, preload and buckling of longitudinal bars. Although different theoretical studies have been carried out to calculate the confin…
Testing mechanical characteristics of chestnut stakes used in bed sills for stream restoration
2017
Using of wood elements for constructing bed sills in Mediterranean streams, where the banks are not protected by tree vegetation, needs an evaluation of biological and mechanical characteristics for evaluating both the wood durability and the effectiveness of the stream restoration project. Very few studies have dealt both with the decay of mechanical characteristics of wood elements employed for stream restoration works and with the changes over time of physical and chemical wood characters. In this paper, for a wood and stone bed sill located in a stream having no shaded banks, the changes of physical and chemical characters detected after 12, 18, 24, 30, 36, 42 and 48 months on chestnut …
A bottom-up approach for the evaluation of the flexible quota of aggregated loads
2015
The paper presents a bottom-up approach for building the aggregated load profile of numerous passive/active users connected to the low voltage electrical system. The approach is based on the Monte Carlo method and on the knowledge of the single electric and thermal loads, generators and thermal and geometrical characteristics of the building of the single end-user. The method proposed is able to differentiate the quota of flexible and not flexible aggregate load.
A new quasi-static multi-degree of freedom tapered roller bearing model to accurately consider non-Hertzian contact pressures in time-domain simulati…
2014
The accuracy of the fatigue life calculations in rolling bearing simulations is highly dependent on the precision of the roller-raceway contact simulations and the ability to accurately include structural deflections of the supporting structure. Several different methods exist to simulate the pressure distributions, and in time-domain bearing simulations, where many contacts need evaluation, the simple and time efficient methods are more popular. These methods underestimate the fatigue life reduction due to roller end effects, overload and misalignments. Furthermore, existing time-domain rolling bearing models assume that the bearing rings remain circular, which can be a poor approximation…
Conceptual design of prestressed slab bridges through one-way flexural load balancing
2013
In this paper a study on prestressed concrete slab bridges is presented. A design philosophy based on the concept of load balancing through prestressing is proposed in order to minimize the effects of delayed deformations due to creep. Aspects related to the stress redistribution inside these bridges for time-dependent phenomena are analyzed and discussed, by applying the principles of aging linear visco-elasticity. Prestressing is seen as an equivalent external load which counterbalances the permanent loads applied to the bridge, nullifying the elastic deflections due to sustained loads, and thus avoiding the related delayed deformations. An optimization of the structural behavior through …
Analytical prediction of load deflection curves of external steel fibers R/C beam–column joints under monotonic loading
2015
Abstract In this paper a simplified analytical model able to reproduce the flexural behavior of external beam–column joints under monotonic loading is presented, to be used for pushover analysis. The subassemblage (beam, column and joint) is subjected to a constant vertical load acting on the column and to a monotonically increasing lateral force applied at the tip of the beam. The model is specific for hooked steel fiber-reinforced concrete (FRC) and is designed to calculate the flexural response in the form of a load–deflection curve, of beam–column subassemblages. No bond failure and shear deformations are considered in the present paper. The model includes shear-to-moment interaction fo…
Analysis of Offshore Knuckle Boom Crane - Part One: Modeling and Parameter Identification
2013
This paper presents an extensive model of a knuckle boom crane used for pipe handling on offshore drilling rigs. The mechanical system is modeled as a multi-body system and includes the structural flexibility and damping. The motion control system model includes the main components of the crane's electro-hydraulic actuation system. For this a novel black-box model for counterbalance valves is presented, which uses two different pressure ratios to compute the flow through the valve. Experimental data and parameter identification, based on both numerical optimization and manual tuning, are used to verify the crane model. The demonstrated modeling and parameter identification techniques target…