Search results for " EFFICIENCY"
showing 10 items of 1091 documents
Joint Usage of Dynamic Sensitivity Control and Time Division Multiple Access in Dense 802.11ax Networks
2016
It is well known that in case of high density deployments, Wi-Fi networks suffer from serious performance impairments due to hid- den and exposed nodes. The problem is explicitly considered by the IEEE 802.11ax developers in order to improve spectrum efficiency. In this pa- per, we propose and evaluate the joint usage of dynamic sensitivity con- trol (DSC) and time division multiple access (TDMA) for improving the spectrum allocation among overlapping 802.11ax BSSs. To validate the solution, apart from simulation, we used a testbed based on the Wireless MAC Processor (WMP), a prototype of a programmable wireless card.
Analysis of interference avoidance with load balancing in heterogeneous cellular networks
2016
In heterogeneous cellular networks (HCNets) smallcells are overlaid with macro-cells to handle heavy cellular data traffic in an efficient way. To achieve fast and reliable access to data with a better coverage it is necessary to offload users to the underutilized small-cells from the congested macro-cells. Sharing of the same licensed frequency spectrum by smallcells and macro-cells results in heavy cross-tier interference which significantly affects the downlink SINR. In this paper, we investigate and analyze a joint frequency-division duplex based cross-tier complementary spectrum sharing technique which is also regarded as reverse frequency allocation (RFA) scheme with load balancing. T…
European Energy Efficiency Evaluation Based on the Use of Super-Efficiency Under Undesirable Outputs in SBM Models
2020
Although Data Envelopment Analysis models have been intensively used for measuring efficiency, the inclusion of undesirable outputs has extended their use to analyse relevant fields such as environmental efficiency. In this context, slacks-based measure (SBM) models offer a remarkable alternative, largely due to their ability to deal with undesirable outputs. Additionally, super-efficiency evaluation in DEA is a useful complementary analysis for ranking the performance of efficient DMUs and even mandatory for dynamic efficiency evaluation. An extension to this approach in the presence of undesirable outputs is here introduced and then applied in the context of the environmental efficiency i…
Adaptive Vehicle Mode Monitoring Using Embedded Devices with Accelerometers
2012
Monitoring of specific attributes such as vehicle speed and fuel consumption as well as cargo safety is an important problem for transport domain. This task is performed using specific multiagent monitoring systems. To ensure secure operation of such systems they should have autonomous and adaptive behaviour.
Functional consequences of prey acclimation to ocean acidification for the prey and its predator
2016
Ocean acidification is the suite of chemical changes to the carbonate system of seawater as a consequence of anthropogenic carbon dioxide (CO2) emissions. Despite a growing body of evidences demonstrating the negative effects of ocean acidification on marine species, the consequences at the ecosystem level are still unclear. One factor limiting our ability to upscale from species to ecosystem is the poor mechanistic understanding of the functional consequences of the observed effects on organisms. This is particularly true in the context of species interactions. The aim of this work was to investigate the functional consequence of the exposure of a prey (the mussel Brachidontes pharaonis) t…
Dynamic preparation of TiO2 films for fabrication of dye-sensitized solar cells
2006
Preparation of nanocrystalline porous titanium dioxide (TiO2) films with roll-to-roll compatible methods was studied. Gravure printing was used for spreading TiO2 paste and paper calendering for pressing TiO2 nanoparticle films. Influence of different preparation methods on performance of fabricated dye-sensitized solar cells (DSSCs) was investigated. The attained light into electricity conversion efficiency was compared with DSSCs fabricated on conductive plastic substrates by doctor-blading spreading with subsequent static pressing. The latter method achieved a light conversion efficiency as high as 5.1%. The efficiency of the cells with a gravure printed TiO2 film was found to be rather …
Characterization of quantum dot/conducting polymer hybrid films and their application to light-emitting diodes.
2009
Quantum dot/conducting polymer hybrid films are used to prepare light-emitting diodes (LEDs). The hybrid films (CdSe@ZnS quantum dots excellently dispersed in a conducting polymer matrix, see figure) are readily prepared by various solution-based processes and are also easily micropatterned. The LEDs exhibit a turn-on voltage of 4 V, an external quantum efficiency greater than 1.5%, and almost pure-green quantum-dot electroluminescence.
Ecological Efficiency of Voluntary Conservation of Boreal-Forest Biodiversity
2008
Current networks of protected areas are biased in many countries toward landscapes of low productivity. Voluntary conservation incentives have been suggested as a socially acceptable way to supplement existing networks with more productive, privately owned areas of high priority for nature conservation. The limited resources committed to nature conservation demand cost-efficiency. Efficiency, however, depends not only on costs incurred to society from alternative ways of maintaining biodiversity but also on ecological values that can be captured. We examined the ecological efficiency of the new market-based voluntary program to preserve forest habitats on private land in southwestern Finlan…
Definition and Assessment of a BAC Factor for Estimating Electrical Consumption of Outdoor Lighting
2018
The BAC factors method was introduced by the international Standard EN 15232 for a rough evaluation of energy savings in buildings obtained thanks to automation. The above standard considers the building's services such as heating, cooling, ventilation and lighting and takes into account automation on the basis of assumed usage profile for the related technical installations. However, the standard does not refer specifically to the automation of outdoor lighting systems such as those serving gardens, entrance walkways and passages around the building and supplied by it. In this paper, the authors propose a method for evaluation an outdoor BAC factor for lighting system considering various s…
Smart city and public lighting
2015
The smart city is increasingly becoming a concept of reference for what concerns the planning and the spatial development of cities. The concept of smart city cannot be easily standardized. It is based on a multi-service and multi-sectorial planning regarding various urban functions (energy, mobility, waste, etc.) and places them under a common denominator: the use of advanced technologies for minimizing resources consumption and simultaneously increase the quality of life of the citizens. This paper aims to give an overview on the concept of smart city and outline what, at present, are the main intervention areas considered at European level. Then the paper focuses on the public lighting t…