Search results for "efficiency."
showing 10 items of 1362 documents
Novel method and instruments for the optimal techno-economic sizing of borehole heat exchangers
2021
El test de respuesta térmica (TRT) es ampliamente utilizado como método estándar para caracterizar las propiedades térmicas del terreno adyacente a un intercambiador de calor enterrado (BHE). Los métodos tradicionales para interpretar los resultados aplican soluciones analíticas o numéricas asumiendo que el terreno es infinito, homogéneo e isotrópico. Sin embargo, en realidad el subsuelo presenta generalmente una estructura estratificada y heterogénea, y por lo tanto las propiedades térmicas pueden variar sustancialmente con la profundidad. En este sentido y con la intención de resolver las limitaciones del TRT estándar, la presente tesis doctoral se centra en el desarrollo de métodos e ins…
Broadening Access to Primary Education: Contract Teacher Programs and Their Impact on Education Outcomes in Africa – An Econometric Evaluation for Ni…
2006
06004; For Sub-Saharan Africa as a whole, but particularly for countries in the Sahel zone, full primary enrolment and completion at acceptable quality as codified in the Millennium Development Goals and the Education for All objectives still remains a major challenge. In order to enhance education supply, many of these countries have launched large scale teacher recruitment programs in recent years, whereby the teachers are no longer engaged in civil servant positions, but on the basis of fixed-term contracts typically implying considerably lower salaries and a sharply reduced duration of professional training. While this policy has led to a boost of primary enrolment, stakeholders in the …
Technical efficiency and regional disparities in Italy
2019
This paper is a contribution to the literature on Italy's regional disparities with a focus on the nature and determinants of firms' technical efficiency. Our analysis concerns a vast number of Italian firms for the decade 2008-2017 and considers the firms that are annually obliged to deposit their balance sheet. A frontier stochastic analysis is used as a method for estimating the technical efficiency of each firm. Our results offer a detailed representation on a provincial basis of disparity gaps. Moreover econometric analysis provides convincing evidence on the importance of territorial variables in the determinants of technical efficiency.
Smart cities: a policy tool for city efficiency?
2016
The level of interest in smart cities has been growing during these last years. The academic literature (Hollands, 2008; Caragliu et al., 2009, Nijkamp et al., 2011 and Lombardi et al., 2012) has identified a number of factors that characterise a city as smart, such as economic development, business-friendly, environmental sustainability, social innovation, information and knowledge process, and human and social capital. Thus, the smartness concept is strictly linked to urban efficiency in a multifaceted way as well as to citizens’ wellbeing through the use of appropriate technologies. Instead, from a “political perspective” smartness is mainly related to the ability of using ICT as instrum…
Graphic model for evaluating the competitiveness and eco-efficiency of eco-innovative projects
2019
Eco-innovation describes the creation of novel and competitively priced goods, processes, systems, services, policies, and procedures that satisfy human needs and improve the quality of life while ensuring sustainable development with minimal use of natural resources and minimal release of toxic substances. This article delves into one of the most pressing problems in improving the assessment of eco-innovative projects meant to effect sustainable development. The article also proposes new criteria for evaluating eco-innovation projects. The purpose is to develop and propose a graphic model by which to assess the innovativeness, competitiveness, and eco-efficiency of eco-innovation projects.…
In Situ Regeneration of Copper-Coated Gas Diffusion Electrodes for Electroreduction of CO2 to Ethylene
2021
This research was funded by the European Union’s Horizon 2020 research and innovation program under grant agreement No 768789 as well as by the Polish National Centre of Science under grant no 2017/26/D/ST8/00508. The Institute of Solid State Physics, University of Latvia, as a center of excellence, has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement no. 739508, project CAMART2.
Unintended Effects of Energy Efficiency Policy: Lessons Learned in the Residential Sector
2021
The European Union has set an ambitious goal to tackle climate change, and energy efficiency in the residential sector is among the measures required to close the gap between targeted and actual greenhouse gas emissions. While different policy tools have been applied, the diffusion rate of these measures remains low. A system dynamics simulation model of the residential sector was developed to assess the advantages and drawbacks of energy efficiency policy in the multi-family building sector based on experience accumulated over the last twelve years in Latvia. The model was validated in expert group model building sessions and with historical trends. Simulating the model, a hypothesis was t…
Analytical Modeling of the Maximum Power Point with Series Resistance
2021
This paper presents new analytical expressions for the maximum power point voltage, current, and power that have an explicit dependence on the series resistance. An explicit expression that relates the series resistance to well-known solar cell parameters was also derived. The range of the validity of the model, as well as the mathematical assumptions taken to derive it are explained and discussed. To test the accuracy of the derived model, a numerical single-diode model with solar cell parameters whose values can be found in the latest installment of the solar cell efficiency tables was used. The accuracy of the derived model was found to increase with increasing bandgap and to decrease wi…
On the Variability of the Temperature Coefficients of mc-Si Solar Cells with Irradiance
2016
Abstract The temperature sensitivity of silicon solar cells is in general assumed to be constant with irradiance in PV forecasting models, although it has been demonstrated experimentally that this is not true. In this study a theoretical model is established that describes the variation of the temperature coefficients of a silicon solar cell as a function of the irradiance. It is shown that the temperature sensitivity of the solar cell efficiency is decreasing with the irradiance and that the main reason for this behavior comes from the increase of the open-circuit voltage with light intensity. Moreover, a dependency of the cell's ideality factor on the irradiance has to be assumed to rece…
Experimental model-based linearization of a S.I. engine gas injector flow chart:
2014
Experimental tests previously executed by the authors on the simultaneous combustion of gasoline and gaseous fuel in a spark ignition engine revealed the presence of strong nonlinearities in the lower part of the gas injector flow chart. These nonlinearities arise via the injector outflow area variation caused by the needle impacts and bounces during the transient phenomena that take place in the opening and closing phases of the injector and may seriously compromise the air-fuel mixture quality control for the lower injection times, thus increasing both fuel consumption and pollutant emissions. Despite the extensive literature about the operation and modelling of fuel injectors, there are …