Search results for "Energy engineering"
showing 10 items of 1099 documents
The influence of the raw material and production method on the morphology, microstructure, chemical and phase composition of tetrabasic lead sulfate …
1992
Abstract Tetrabasic lead sulfate (4BS) produced by two different methods (solution and paste) and from two different raw materials (tetragonal PbO and leady oxide) were charaterized by different analytical techniques. The techniques applied were wet-chemical methods, scanning electron microscopy, transmission electron microscopy and X-ray powder diffraction. The preparation method was observed to be the most decisive factor influencing the structure and the morphology of the 4BS pastes in this study.
Exploring the Hedging Effectiveness of European Wheat Futures Markets during the 2007-2012 Period
2014
Abstract The hypothesis that speculative behaviour was the cause of the instability of commodity prices has brought renewed interest in futures markets. In this paper, the hedging effectiveness of European and US wheat futures markets were studied to test whether they were affected by the price instability observed after 2007. Indirectly, this could also be thought as a test of whether the increasing presence of speculators in futures markets have made them divorced from physical markets. A multivariate GARCH model was applied to compute optimal hedging ratios. No important evidence was found of a change in the hedging effectiveness after 2007.
Synergistic effects of multiwalled carbon nanotubes and Al on the electrochemical hydrogen storage properties of Mg2Ni-type alloy prepared by mechani…
2012
Abstract Mg 2− x Al x Ni ( x = 0, 0.25) electrode alloys with and without multiwalled carbon nanotubes (MWCNTs) have been prepared by mechanical alloying (MA) under argon atmosphere at room temperature using a planetary high-energy ball mill. The microstructures of synthesized alloys are characterized by XRD, SEM and TEM. XRD analysis results indicate that Al substitution results in the formation of AlNi-type solid solution that can interstitially dissolve hydrogen atoms. In contrast, the addition of MWCNTs hardly affects the XRD patterns. SEM observations show that after co-milling with 5 wt. % MWCNTs, the particle sizes of both Mg 2 Ni and Mg 1.75 Al 0.25 Ni milled alloys are decreased e…
Mg2-xTixNi (x=0, 0.5) alloys prepared by mechanical alloying for electrochemical hydrogen storage: Experiments and first-principles calculations
2012
International audience; Mg2-xTixNi (x = 0, 0.5) electrode alloys have been prepared by mechanical alloying (MA) under argon atmosphere at room temperature using a planetary high-energy ball mill. The microstructures of synthesized alloys are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of substitutional doping of Ti in Mg2Ni phase have been investigated by first-principles density functional theory calculations. XRD analysis results indicate that Ti substitution for Mg in Mg2Ni-type alloys results in the formation of TiNi (Pm-3m) and TiNi3 intermetallics. With the increase of milling time, the TiNi phase…
Growth mechanisms and related thermoelectric properties of innovative hybrid networks fabricated by direct deposition of Bi2Se3 and Sb2Te3 on multiwa…
2020
Abstract Flexible thermoelectric generators are an emerging trend in the field of waste heat conversion, as well as wearable and autonomous devices. However, the energy conversion efficiency of the state-of-the-art flexible thermoelectric devices is too low for their wide application and commercialization. In this work, n- and p-type multiwalled carbon nanotube (MWCNT)-thermoelectric material hybrid networks that may become a promising building block for the fabrication of flexible thermoelectric devices are presented. The hybrid networks were fabricated by direct deposition of thermoelectric material (Bi2Se3, Sb2Te3) on the MWCNT networks using physical vapor deposition technique. Growth m…
Enhancement of photoelectrochemical activity for water splitting by controlling hydrodynamic conditions on titanium anodization
2015
This work studies the electrochemical and photoelectrochemical properties of a new type of TiO2 nanostructure (nanosponge) obtained by means of anodization in a glycerol/water/NH4F electrolyte under controlled hydrodynamic conditions. For this purpose different techniques such as Scanning Electronic Microscopy (SEM), Raman Spectroscopy, Electrochemical Impedance Spectroscopy (EIS) measurements, Mott–Schottky (M−S) analysis and photoelectrochemical water splitting tests under standard AM 1.5 conditions are carried out. The obtained results show that electron–hole separation is facilitated in the TiO2 nanosponge if compared with highly ordered TiO2 nanotube arrays. As a result, nanosponges en…
Economie assessments on the use of wired and wireless recharging systems in Italian and European market
2017
The conductive charging method for the electric vehicles is the most widespread, since it is the simplest and has higher returns. In the last years, alternative charging technologies have been investigated. Between these wireless charging systems have been large diffusion and have been commercialized by some manufacturer. Wireless charging systems for electric vehicles have some advantages respect the wired ones, not obliging the user to connect physically the vehicle to the electric charging station. Assuming the efficiency declared by the manufacturer of wireless systems the authors, in this paper, estimate the maximum cost that wireless recharging systems can have to be, however, more fa…
Economic analysis on the use of wired and wireless recharging systems
2017
Wireless charging systems for electric vehicles have some advantages respect the wired ones, not obliging the user to connect physically the vehicle to the electric charging station. However, at the same time, they have disadvantages linked to issues of electromagnetic compatibility and low efficiency. This study considers some scenarios for which both wired and wireless recharging systems can be adopted, with the aim of estimate the efficiency that must be guaranteed by wireless systems, so that its realization could be more favorable with respect to wired one. The estimation is developed by means of classical economic indexes, in the framework of Italian end European markets. Results repo…
Non-linear neuro-inspired circuits and systems: Processing and learning issues
2018
In this chapter the main elements useful for the design and realization of the neural architectures reported in the following chapters will be presented. Considering spiking and non-spiking neurons, the models used for implementing each of them, the synaptic models, the basic learning and plasticity algorithms and the network architectures will be introduced and analysed. The key elements that led to their selection and application in the developed neuro-inspired systems will be discussed briefly.
CO<SUB align="right">2 prices and portfolio management
2011
Since the launch of the European Union Emission Trading Scheme (EU ETS), the interest in the trade of EUAs is constantly increasing among academics and market participants. The objective of this paper is twofold: (a) a detailed description of this new market is provided for portfolio managers and (b) a comprehensive study of the implications of including Phase II EUAs in diversified portfolios is undertaken using as expected returns both historical and risk-adjusted returns. The results show that the opportunity set for investors increases when short positions in Phase II EUAs are taken.