Search results for "efficiency."
showing 10 items of 1362 documents
Emerging topics in scientific research on global water-use efficiency
2019
AbstractA bibliometric analysis of research articles published on water-use efficiency was performed using the Web of Science database and evaluated. Journal titles, publication years, subject categories, keywords and countries publishing were obtained. A number of 2077 papers were retrieved, two-thirds of them published in the last decade. The articles were published in 439 journals, with Agricultural Water Management, Agronomy Journal, Crop Science, Field Crops Research and Indian Journal of Agricultural Sciences the most productive. Most of the leading productive journals have Impact Factors in the top quartiles of the Journal Citation Reports. Agronomy, Plant Sciences, Water Resources a…
Dynamic wavefront sensing and correction with low-cost twisted nematic spatial light modulators
2010
Off-the-shelf spatial light modulators (SLMs), like twisted nematic liquid crystal displays (TNLCDs) used in projection systems, show some interesting features such as high spatial resolution, easy handling, wide availability, and low cost. We describe a compact adaptive optical system using just one TNLCD to measure and compensate optical aberrations. The current system operates at a frame rate of the order of 10 Hz with a four-level codification scheme. Wavefront estimation is performed through conventional Hartmann–Shack sensing architecture. The system has proved to work properly with a maximum rms aberration of 0. 76 μm and wavefront gradient of 50 rad/mm at a wavelength of 514 nm. The…
Modelling of Laser Operation in RPE Nd3+:LiNbO3 Channel Waveguides
2006
In this work, laser action in RPE Nd3+:LiNbO3 is modelled by using the overlapping integrals method. Different pumping schemes, TE or TM, have been considered in order to reproduce the experimental measurements. Calculated results indicate that the slope efficiency remains basically independent on the pumping scheme while the threshold pump power increases for TE pumping.
Energy-aware design for wireless mesh networks
2014
International audience; Wireless mesh networks (WMNs) are the next step in the development of the wireless architecture, delivering wireless services for a large variety of users in personal, local, campus, and metropolitan areas. Energy efficiency solutions are becoming more vital for both local access networks and wireless networks and Green IT has attracted a considerable attention. However, the application of green network for wireless mesh networks has seldom been described in the literature. However, WMNs infrastructure devices are always active. Thus, during lower traffic periods the energy consumption is the same as in busy hours, while it would be possible to save a large amount of…
Energy efficient and distributed resource allocation for wireless powered OFDMA multi-cell networks
2017
In this paper, we investigate the energy efficient resource allocation problem for the wireless powered OFDMA multi-cell networks. In the considered system, the users who have data to transmit in the uplink can only be empowered by the wireless power obtained from multiple base stations (BSs) with a large scale of multiple antennas in the downlink. A time division protocol is considered to divide the time of wireless power transfer (WPT) in the downlink and wireless information transfer (WIT) in the uplink into separate time slot. With the objective to improve the energy efficiency (EE) of the system, we propose the antenna selection, time allocation, subcarrier and power allocation schemes…
Sustainable architecture for wine cellars
2020
Environmental sustainability in the wine sector is one of the major factors of commercial interest for consumers and producing companies. The link between wine production, territory and architectural typology of wine cellars is always more important for the food and wine sector. This work explores the connections between architecture and energy efficiency with regards to minimizing environmental impacts in wine production and the sustainable use of resources in production processes. The role of economic and cultural promotion of wine cellars with bioclimatic architecture towards the tourism industry is highlighted.
Hierarchizing Energy Saving Strategies in Wine Industry by Advanced Modelling of Chilling Units Operation
2019
Wineries are energy intensive industries and in order to make the production process more sustainable, solutions for an efficient use of energy should be implemented. Large surveys conducted in the wineries sector have highlighted the importance of performing accurate energy audits and have identified in the installation of efficient cooling/refrigeration systems the most promising solutions in a variety of cases. Unfortunately, the savings achieved by such energy efficient solutions is often calculated by highly simplified approaches, which do not take into consideration the actual operating conditions of the equipment (highly variable on a seasonal and daily basis). In this paper a system…
Towards the first proof of the concept of a Reverse ElectroDialysis - Membrane Distillation Heat Engine
2019
Abstract The coupling of Reverse Electrodialysis with Membrane Distillation is a promising option for the conversion of waste heat into electricity. This study evaluates the performances of the integrated system under different operating conditions, employing validated model and correlations. This work provides a detailed description of the behaviour of a real RED-MD heat engine and indicates the set of inlet concentrations, velocities and equipment size which returns the highest cycle exergy efficiency. These operating conditions were selected for the pilot plant developed within the EU-funded project RED Heat to Power. For the first time, a perspective analysis was also included, consider…
Thermolytic reverse electrodialysis heat engine: model development, integration and performance analysis
2019
Abstract Salinity gradient heat engines represent an innovative and promising way to convert low-grade heat into electricity by employing salinity gradient technology in a closed-loop configuration. Among the aqueous solutions which can be used as working fluid, ammonium bicarbonate-water solutions appear very promising due to their capability to decompose at low temperature. In this work, an experimentally validated model for a reverse electrodialysis heat engine fed with ammonium bicarbonate-water solutions was developed. The model consists of two validated sub-models purposely integrated, one for the reverse electrodialysis unit and the other for the stripping/absorption regeneration uni…
Theoretical efficiency limits for thermoradiative energy conversion
2015
Published version of an article in the journal: Journal of Applied Physics. Also available from the publisher at: http://dx.doi.org/10.1063/1.4907392 A new method to produce electricity from heat called thermoradiative energy conversion is analyzed. The method is based on sustaining a difference in the chemical potential for electron populations above and below an energy gap and let this difference drive a current through an electric circuit. The difference in chemical potential originates from an imbalance in the excitation and de-excitation of electrons across the energy gap. The method has similarities to thermophotovoltaics and conventional photovoltaics. While photovoltaic cells absorb…