Search results for "maximum"
showing 10 items of 753 documents
The Liouville theorem and linear operators satisfying the maximum principle
2020
A result by Courr\`ege says that linear translation invariant operators satisfy the maximum principle if and only if they are of the form $\mathcal{L}=\mathcal{L}^{\sigma,b}+\mathcal{L}^\mu$ where $$ \mathcal{L}^{\sigma,b}[u](x)=\text{tr}(\sigma \sigma^{\texttt{T}} D^2u(x))+b\cdot Du(x) $$ and $$ \mathcal{L}^\mu[u](x)=\int \big(u(x+z)-u-z\cdot Du(x) \mathbf{1}_{|z| \leq 1}\big) \,\mathrm{d} \mu(z). $$ This class of operators coincides with the infinitesimal generators of L\'evy processes in probability theory. In this paper we give a complete characterization of the translation invariant operators of this form that satisfy the Liouville theorem: Bounded solutions $u$ of $\mathcal{L}[u]=0$ i…
Conductance of potassium halides near the temperature of maximum density of water
1981
The conductances of dilute aqueous solutions of KCl, KBr, and KI have been measured over the temperature range 2 to 8°C and have been analyzed by the Fuoss-Hsia equation. The ionic Walden products at infinite dilution have been discussed in terms of local viscosity. The temperature dependence of these products suggest that near the temperature of maximum density of water, the structure-breaking ability of these ions changes in a regular way.
Assessment of the Operating Temperature of Crystalline PV Modules Based on Real Use Conditions
2014
Determining the operating temperatureTcof photovoltaic panelsPVis important in evaluating the actual performance of these systems. In the literature, different correlations exist, in either explicit or implicit forms, which often do not account for the electrical behaviour of panels; in this way, estimatingTcis based only on the passive behaviour of thePV. In this paper, the authors propose a new implicit correlation that takes into account the standard weather variables and the electricity production regimes of aPVpanel in terms of the proximity to the maximum power points. To validate its reliability, the new correlation was tested on two different PV panels (Sanyo and Kyocera panels) and…
Morphology-based measurement of activation time in human atrial fibrillation
2003
The measurement of the activation time is crucial to allow the correct automatic analysis and classification of intracardiac electrograms recorded in the human atria during atrial fibrillation (AF). This study proposes a method which accounts for the morphology of bipolar signals. After ventricular artifact removal and activation wave recognition, the fiducial point of the activation wave was set at its local barycentre (LB). The method was tested on a set of 30 AF bipolar recordings of increasing complexity class; its performance was compared with that of the traditional methods of maximum peak (MP) or maximum slope (MS) estimation, taking the manual measurements performed by an expert car…
Comparison of the H-alpha circumstellar disks in Be/X-ray binaries and Be stars
2000
We present a comparative study of the circumstellar disks in Be/X-ray binaries and isolated Be stars based upon the H-alpha emission line. From this comparison it follows that the overall structure of the disks in the Be/X-ray binaries is similar to the disks of other Be stars, i.e. they are axisymmetric and rotationally supported. The factors for the line broadening (rotation and temperature) in the disks of the Be stars and the Be/X-ray binaries seem to be identical. However, we do detect some intriguing differences between the envelopes. On average, the circumstellar disks of the Be/X-ray binaries are twice as dense as the disks of the isolated Be stars. The different distribution of the…
Recent temporal and spatial temperature changes in Egypt
2005
In order to detect and to estimate trends of temperature change in Egypt, trend analyses applying the least-squares method and the non-parametric Mann–Kendall test for trends were carried out at six stations for the period 1941–2000 (60 years), and at nine stations for the period 1971–2000 (30 years). According to the trend computations for the period 1941–2000, variable temperature trends over time and space have been observed. Decreasing trends of the mean annual temperature were observed in northern Egypt and (weakly) increasing trends in southern Egypt. Seasonally, positive trends prevailed in summer compared with negative trends in winter. For the recent period, 1971–2000, positive tre…
Seismic stratigraphy of upper Quaternary shallow-water contourite drifts in the Gulf of Taranto (Ionian Sea, southern Italy)
2018
Abstract The occurrence of articulated seafloor morphology over continental shelf-upper slope environments, may result in a significant change in the patterns and intensity of basin-scale thermohaline circulation during eustatic sea-level fluctuations. These changes may cause, in turn, erosion, deposition and/or transport of sediments at the seafloor, to form shallow-water contourite drifts. Here we investigate this process in the NW sector of the Gulf of Taranto (Ionian Sea) during and following the Last Glacial Maximum (LGM), by integrating multibeam bathymetric data, ultra-high resolution seismic-reflection data and gravity core data. Sea level fall caused subaerial exposure of the summi…
Computer Fluid Dynamics Assessment of an Active Ventilated Façade Integrating Distributed MPPT and Battery
2019
Ventilated Façades integrated with photovoltaic panels have become a popular way to improve both the thermal-physical performances of the existing built environment. The increased usage of not-programmable renewable energy sources implies the adoption of energy storage systems to mitigate the mismatch between the power generation and the building’s demand. Aiming at properly integrates a photovoltaic panel and a battery (Lithium based) as a module of an active ventilated façade, the prototype design has been carried out in terms of thermo-fluid dynamics performance. Based on experimental setup, a numerical study of flow through the air cavity of the active ventilated façade has been carried…
Design, implementation and experimental results of a wireless charger for E-bikes
2019
Based on the Inductive Power Transfer (IPT), the wireless energy transmission is increasingly representing an attractive solution for vehicle battery charging. Due to its high smartness, the wireless solution may be considered an interesting battery charging method for electric bicycles, as they represent light-weight and flexible means of transportation. According to the Vehicle-To-Grid (V2G) concept, the wireless power flow can occur in both the alternative directions: from the grid to the battery or in the opposite way. A Bi-Directional Inductive Power Transfer (BDIPT) system is therefore particularly convenient in the scenario of a multi-parking area. For the E-bike application, a bicyc…
Efficiency optimization in bi-directional inductive power transfer systems
2015
Inductive Power Transfer (IPT) allows to wirelessly supply electronic devices. Thus, it is a very smart technique of battery charging for electric vehicles. In a parking area scenario, IPT is a proper method aiming at the energy transfer from the vehicle battery to the electric grid too. Bi-Directional Inductive Power Transfer (BDIPT) Systems are an attractive solution for the automotive market. Due to the great relevance of the energy saving problem, the goal of an efficiency maximization is researched by the energy market. In this paper, an in-depth investigation of the power efficiency in BDIPT systems is carried out, aiming at the optimum efficiency.