Search results for "efficiency"
showing 10 items of 1430 documents
Gender and potential wage in Europe: a stochastic frontier approach
2011
PurposeThe purpose of this paper is to provide evidence concerning wage differentials and the existence of gender pay discrimination in France, Germany, Italy, Spain and the United Kingdom.Design/methodology/approachThe authors used the stochastic frontier approach as an alternative method to measure the relevance of gender discrimination. This methodology allows them to explain the differences between the potential and the observed wage that an individual could obtain, given his or her human capital endowment.FindingsThe authors found support for wage discrimination against women. The results show that a significant part of the gender wage gap in all the countries analysed is not attributa…
Material Substitution for Automotive Applications: A Comparative Life Cycle Analysis
2012
Lightweight materials have become an important strategy in the automotive industry to enable vehicle weight reduction and reduce fuel consumption. However, when developing specific strategies, the overall benefits of any material should be analyzed throughout its life cycle to comprehend energy/environmental differences that arise during its processing and its final use. A key example is aluminum which despite having great potential in the use phase requires large amounts of energy to process. This paper provides a comparison between aluminum and steel utilizing a life-cycle approach. This approach reveals the importance of incorporating a recycling strategy to leverage aluminum’s low-weigh…
An Intelligent System for Energy Efficiency in a Complex of Buildings
2012
Energy efficiency has nowadays become one of the most challenging task for both academic and commercial organizations, and this has boosted research on novel fields, such as Ambient Intelligence. In this paper we address the issue of timely and ubiquitous monitoring of building complexes in order to optimize their energy consumption, and present an intelligent system addressed to the typical end user, i.e. the administrator, or responsible operator, of the complex. A three-level architecture has been designed for detecting the presence of the building inhabitants user and understanding their preferences with respect to the environmental conditions in order to optimize the overall energy eff…
A qualitative examination of performance and energy yield of photovoltaic modules in southern Norway
2010
Three different, commercially available photovoltaic modules have been monitored outdoors in the town of Grimstad, Norway. The present paper describes the experimental setup that was implemented, in particular details of the low-cost electronic loads. Results compare measured performance with manufacturer's data, and temperature measurements enable a comparison with performance at standard test condition temperature. Overall, the monocrystalline module performed best both regarding maximum efficiency and overall energy production, whereas the module based on triple junction amorphous silicon technology had the worst performance considering these criteria. The gross numbers of energy yield c…
Plasmonic and diffractive nanostructures for light trapping—an experimental comparison
2015
Metal nanoparticles and diffractive nanostructures are widely studied for enhancing light trapping efficiency in thin-film solar cells. Both have achieved high performance enhancements, but there are very few direct comparisons between the two. Also, it is difficult to accurately determine the parasitic absorption of metal nanoparticles. Here, we assess the light trapping efficiencies of both approaches in an identical absorber configuration. We use a 240 nm thick amorphous silicon slab as the absorber layer and either a quasi-random supercell diffractive nanostructure or a layer of self-assembled metal nanoparticles for light trapping. Both the plasmonic and diffractive structures strongly…
High-efficiency silicon-compatible photodetectors based on Ge quantum dots
2011
We report on high responsivity, broadband metal/insulator/semiconductor photodetectors with amorphous Ge quantum dots (a-Ge QDs) as the active absorbers embedded in a silicon dioxide matrix. Spectral responsivities between 1-4 A/W are achieved in the 500-900 nm wavelength range with internal quantum efficiencies (IQEs) as high as ∼700%. We investigate the role of a-Ge QDs in the photocurrent generation and explain the high IQE as a result of transport mechanisms via photoexcited QDs. These results suggest that a-Ge QDs are promising for high-performance integrated optoelectronic devices that are fully compatible with silicon technology in terms of fabrication and thermal budget. © 2011 Amer…
Influence of the electro-optical properties of an a-Si:H single layer on the performances of a pin solar cell
2012
We analyze the results of an extensive characterization study involving electrical and optical measurements carried out on hydrogenated amorphous silicon (α-Si:H) thin film materials fabricated under a wide range of deposition conditions. By adjusting the synthesis parameters, we evidenced how conductivity, activation energy, electrical transport and optical absorption of an α-Si:H layer can be modified and optimized. We analyzed the activation energy and the pre-exponential factor of the dark conductivity by varying the dopant-to-silane gas flow ratio. Optical measurements allowed to extract the absorption spectra and the optical bandgap. Additionally, we report on the temperature dependen…
Should TiO2 nanostructures doped with Li+ be used as photoanodes for photoelectrochemical water splitting applications?
2017
[EN] Different TiO2 nanostructures, nanotubes and nanosponges, were obtained by anodization of Ti under stagnant and hydrodynamic conditions. Samples were doped with Li+ before and after annealing at 450 degrees C during 1 h. The nanostructures were characterized by different microscopy techniques: Field Emission Scanning Electron Microscopy (FE-SEM) and Raman Confocal Laser Microscopy. Additionally, Incident Photon-to-electron Conversion Efficiency (IPCE), photoelectrochemical water splitting and stability measurements were also performed. According to the results, TiO2 nanostructures doped before annealing present the worst photocurrent response, even if compared with undoped samples. On …
Valorization of Wastewater from Table Olives: NMR Identification of Antioxidant Phenolic Fraction and Microwave Single-Phase Reaction of Sugary Fract…
2021
The table olive industry is producing a huge amount of wastewater, which is a post-processing cost and an environmental concern. The present study aims to valorize this processing by-product to obtain a value-added product, thereby enhancing resource efficiency and contributing to achieving sustainable development goals (SDGs). In this sense, a chemical reaction-based platform was developed to obtain valuable components, such as levulinic acid (LA) and 5-hydromethylfurfural (HMF). The products were then analyzed using NMR identification of the antioxidant phenolic fraction and microwave single-phase reaction of the sugary fraction. According to the results, the highest concentration of phen…
Electrochemical conversion of pressurized CO2 at simple silver-based cathodes in undivided cells: study of the effect of pressure and other operative…
2020
Abstract Electrochemical reduction of pressurized CO2 is proposed as an interesting approach to overcome the main hurdle of the CO2 electrochemical conversion in aqueous solution, its low solubility (ca. 0.033 M), and to achieve good faradaic efficiency in CO using simple sheet silver cathodes and undivided cells, thus lowering the overall costs of the process. The effect on the process of CO2 pressure (1–30 bar), current density, nature of the supporting electrolyte and other operative conditions, such as the surface of the cathode or the mixing rate, was studied to enhance the production of CO. It was shown that pressurized conditions allow to improve drastically the current efficiency o…