Search results for " EFFICIENCY"
showing 10 items of 1091 documents
Dual-band printed dipole antenna for Wi-Fi 802.11n applications
2010
A dual-band compact printed dipole antenna for Wi-Fi 802.11n applications in the 2.45 and 5.5 GHz bands is presented. The proposed antenna consists of two printed dipoles with the arms located onto both sides of the dielectric substrate and a bended stripline. This feed scheme makes easy the integration of the antenna with the electronic subsystem and avoids the radiation towards the device. For the design and optimisation, a specifically developed finite-difference time-domain based code is used. The antenna has then been fabricated, simulated and measured. The return losses highly match the Wi-Fi frequency specifications with a moderate gain (between 1 and 3 dBi) and efficiency better tha…
Control strategy analysis of the hydraulic hybrid excavator
2015
Abstract Applying the electric hybrid technique on the off-road vehicle is one popular method to reduce the fuel consumption. However, the high cost, low energy conversion efficiency and disposal of used batteries are still the main problems. This paper is focusing on one alternative choice which is hydraulic hybrid off-road vehicles. Among the most typical off-road vehicles, the excavator is chosen as the prototype to study the control strategy. First, the basic principle of the hydraulic hybrid excavator based on Common Pressure Rail is introduced. Then, the mathematical model of the whole excavator is created. Moreover, the dynamic programming algorithm is used to solve the optimal contr…
Environmental Comparison between a Hot Extrusion Process and Conventional Machining Processes through a Life Cycle Assessment Approach
2014
Nowadays manufacturing technologies have to be evaluated not only for the technical features they can provide to products, but also considering the environmental perspective as well. As long as the technological feasibility of a given process is guaranteed, processes minimizing resources and energy consumption have to be selected for manufacturing. With respect to this topic, the research studies in the domain of metal processing technologies predominantly focus on conventional material removal processes as milling and turning. Despite some exceptions, many other non-machining technologies, such as metal forming processes, are still not well documented in terms of their energy and resource …
On the Efficacy of PCM to Shave Peak Temperature of Crystalline Photovoltaic Panels: An FDM Model and Field Validation
2013
The exploitation of renewable energy sources and specifically photovoltaic (PV) devices have been showing significant growth; however, for a more effective development of this technology it is essential to have higher energy conversion performances. PV producers often declare a higher efficiency respect to real conditions and this deviation is mainly due to the difference between nominal and real temperature conditions of the PV. In order to improve the solar cell energy conversion efficiency many authors have proposed a methodology to keep the temperature of a PV system lower: a modified crystalline PV system built with a normal PV panel coupled with a Phase Change Material (PCM) heat stor…
Environmental management of granite slab production from an industrial ecology standpoint
2014
Abstract The granite production chain is high energy and water intensive with low resource efficiency. This paper focus on characterizing the potential for environmental improvement of the granite production chain by promoting the optimization of sawing technology, the implementation of rainwater harvesting (RWH) and the material recovery of wasted granite (sludge). The environmental performance of multi-blade gangsaw (MBGS) and diamond multi-wire saw (DMWS) technologies is compared by mean of life cycle assessment. Results demonstrate that DMWS technology contribute 30% of water savings, 40% of energy savings and 80% of material savings per square meter of polished granite tiles (60 x 40 x…
Addressing the main challenges of energy security in the twenty-first century – Contributions of the conferences on Sustainable Development of Energy…
2016
Abstract Climate change and fossil fuel reserve depletion both pose challenges for energy security and for wellbeing in general. The top ten among them include: Decarbonising the world economy; Enhancing the energy efficiency and energy savings in buildings; Advancing the energy technologies; Moving towards energy systems based on variable renewables; Electrifying the transport and some industrial processes; Liberalizing and extending the energy markets; Integrating energy sectors to Smart Energy Systems; Making the cities and communities smart; Diversifying the energy sources; and Building more biorefineries. Presenting the contributions of selected conference papers published in the speci…
Active load sharing technique for on-line efficiency optimization in DC microgrids
2017
Recently, DC power distribution is gaining more and more importance over its AC counterpart achieving increased efficiency, greater flexibility, reduced volumes and capital cost. In this paper, a 24-120-325V two-level DC distribution system for home appliances, each including three parallel DC-DC converters, is modeled. An active load sharing technique is proposed for the on-line optimization of the global efficiency of the DC distribution network. The algorithm aims at the instantaneous efficiency optimization of the whole DC network, based on the on-line load current sampling. A Look Up Table, is created to store the real efficiencies of the converters taking into account components toler…
Operational efficiency of a pilot plant for wastewater reuse
1996
Reuse of wastewaters for non-potable uses needs a higher than normal reliability in treatment plant operation and management, in order to ensure higher safety margins for public health and environmental protection. After a two-years research project on a pilot plant designed for agricoltural reuse, all control parameters used for the plant operation have been examined, in order to obtain useful observations on efficiency of each of the treatment units, for best overall performance. It was concluded that this type of package plant was able to produce a high quality effluent under various conditions, providing a good confidence on the reliability of the system. Reuse of wastewaters for non-po…
Environmental externalities and efficiency measurement.
2009
Production of desirable outputs often produces by-products that have harmful effects on the environment. This paper investigates technologies where the biggest good output producer is not the greatest polluter, i.e. technologies located on the downward-sloping segment of the frontier depicted in Fare et al. (1989). Directional distance functions and Data Envelopment Analysis techniques are used to define an algorithm that allows them to be identified empirically. Furthermore, we show that in such situations producers can contribute social goods, i.e. reducing polluting wastes, without limiting their capacity to maximise production of marketable output. Finally, we illustrate our methodology…
Finite difference thermal model of a latent heat storage system coupled with a photovoltaic device: Description and experimental validation
2014
Abstract The use of photovoltaic (PV) systems has been showing a significant growth trend but for a more effective development of this technology it is essential to have higher energy conversion performances. Producers of PV often declare an higher efficiency respect to real conditions and this deviation is mainly due to the difference between nominal and real temperature conditions of the PV. To improve the solar cell energy conversion efficiency many authors have proposed a methodology to keep lower the temperature of a PV system: a modified PV system built with a normal PV panel coupled with a Phase Change Material (PCM) heat storage device. In this paper is described a thermal model ana…