Search results for " performance."
showing 10 items of 2429 documents
Photovoltaic plant array reconfiguration: Design of a new device
2014
An efficient strategy to improve unequally irradiated PV plants performances is based on the reconfiguration of the connections between the modules. In this paper, an algorithm, for this purpose conceived, is presented. Moreover, the design, realization and finally also the set up of a new reconfiguration system device is fully shown and discussed. The algorithm conceived simulates several possible series-parallel connections under varying irradiation conditions, and determines the optimal modules connection in order to get the maximum output power. In this way, the reconfiguration system may set up the reconfiguration strategy. The reconfiguration system prototype set up, basically consist…
Long term energy efficiency study on different wall envelopes in Latvian climate conditions
2017
Abstract Five test stands have been built in Riga, Latvia equipped with sensors (temperature, solar radiation, humidity, etc.) to measure energy efficiency and thermal comfort conditions. Roof and floor constructions are made the same. For the walls building envelopes differ and typical materials used in Latvia (aerated concrete, ceramic building blocks, wooden log and plywood frame with rock wool insulation) are compared. Only rock wool is used for insulation to provide moisture transport through the construction. For study to be comparative thermal transmittance of all five test stands have been calculated equal (U=0.15…0.16 W/(m 2 ∙K)). The aim of research is to compare the integral calc…
Optimization model predictions for postural coordination modes
2003
International audience; This paper examines the ability of the dynamic optimization model to predict changes between in-phase and anti-phase postural modes of coordination and to evaluate influence of two particular environmental and intentional constraints on postural strategy. The task studied was based on an experimental paradigm that consisted in tracking a target motion with the head. An original optimal procedure was developed for cyclic problems to calculate hip and ankle angular trajectories during postural sway with a minimum torque change criterion. Optimization results give a good description of the sudden bifurcation phase between in-phase and anti-phase postural coordination mo…
Identification of Defensive Performance Factors in the 2010 FIFA World Cup South Africa
2016
The aim of this study was to determine the efficacy of defensive play in elite football, to identify variables associated with the direct recovery of ball possession, and to propose a model for predicting the success of defensive transitions. We analyzed 804 transitions in the final stages of the Fedération Internationale Football Association (FIFA) World Cup 2010, and investigated the following variables using univariate, bivariate, and multivariate analyses: duration of defensive transition, possession loss zone, position of players at the start and end of the defensive transitions, defensive organization, general defensive approach, time of the match, position of defense, zone in which t…
<title>Evolution of optical links toward full-optical transparency</title>
2003
In this paper we review issues of evolution of optical networks towards their full optical transparency and present sequence of eliminating non-transparent elements out of optical links (networks). Architectures of optical commutators with electrical and optical cores have been presented, as well as a structure of OMO (optical-millimeter wave-optical) switching fabric. An example of pure al-optical switch, made by Luxcore, utilizing dispersion compensating elements, wavelength converters and and variable optical attenuators (VOA) operating entirely in optical domain without optical-electrical-optical (OEO) conversions, was quoted. We brought up an issue of all-optical 3R signal regeneration…
Ultra-Wideband Radio Signals Distribution in FTTH Networks
2008
[EN] The use of an ultra-wideband (UWB) radio technique is proposed as a viable solution for the distribution of high-definition audio/video content in fiber-to-the-home (FTTH) networks. The approach suitability is demonstrated by the transmission of standards-based UWB signals at 1.25 Gb/s along different FTTH fiber links with 25 km up to 60 kin of standard single-mode fiber length in a laboratory experiment. Experimental results suggest that orthogonal frequency-division-multiplexed UWB signals exhibit better transmission performance in FFTH networks than impulse radio UWB signals.
Experimental characterization of PEM fuel cells by micro-models for the prediction of on-site performance
2009
This paper presents the results of an experimental analysis performed on a miniaturized, 6 We Proton Exchange Membrane Fuel Cell (PEMFC) system, integrated with on-site hydrogen production by electrolysis; in particular, the effects of environmental parameters such as the external temperature and the humidity on the performance of fuel cells are investigated. PEMFC systems are zero-emissions power technologies when they are fed with pure hydrogen (at concentration higher than 97%); also, being the only results of system operation the produced electricity and some pure water, when produced by renewable sources hydrogen can be considered an attractive alternative to fossil fuels and may concu…
Reverse electrodialysis
2016
Abstract Reverse electrodialysis (RED) technology has grown significantly in the last decade, gaining a fast increase in its technology readiness level and presenting some interesting examples of RED pilot systems operating under very different real environments. In this chapter, an overview of technological developments and piloting examples are reported. In particular, a short introduction is given on the historical trend of RED technology growth, followed by a careful analysis of which feed solutions can be adopted and how these can affect the process performance, potentials, and applications. Most prominent fluid dynamics aspects for the RED process are presented, highlighting how these…
Evaluation to support stakeholder centered design and continuous quality improvement in higher education services
2014
Abstract: Evaluation and self-evaluation procedures are commonly used in educational institutions to measure education services and research performance. This chapter describes the main opportunities that evaluation-based approaches can produce to support processes of design and continuous quality improvement in higher education institutions in the light of recent normative measures in Italy to address quality aspects of education services. Subsequently, a new approach – based on the ServQual conceptual model – that evaluates education services is used to carry out a strategic analysis of education services at the management engineering program at the University of Palermo, Italy.
Annual heating energy requirements of office buildings in a European climate
2016
Abstract The concept of implementing energy savings to reduce greenhouse gas emissions has become a key element of energy policies of any industrialized country. In the civil sector and specifically, energy savings for office buildings, there are still opportunities for further enhancements related to correctly determining the air conditioning thermal requirements. However, there is a lack of simple correlations that allow a preliminary assessment for a single building or correlations that can be quickly applied at the district level. This paper proposes several simple correlations that determine the heating loads of a typical office building by only knowing the Degree-Days of a specific Eu…