Search results for "POWER"
showing 10 items of 5099 documents
Overdispersion tests in count-data analysis.
2008
Count data are commonly assumed to have a Poisson distribution, especially when there is no diagnostic procedure for checking this assumption. However, count data rarely fit the restrictive assumptions of the Poisson distribution. The violation of much of such assumptions commonly results in overdispersion, which invalidates the Poisson distribution. Undetected overdispersion may entail important misleading inferences, so its detection is essential. In this study, different overdispersion diagnostic tests are evaluated through two simulation studies. In Exp. 1, the nominal error rate is compared under different sample sizes and Λ conditions. Analysis shows a remarkable performance of the χ…
Relations between enabling skills and reading comprehension: a follow-up study of Latvian students from first to second grade.
2004
Sprugevica, I. & Hoien, T. (2004). Relations between enabling skills and reading comprehension: A follow-up study of Latvian students from first to second grade. Scandinavian Journal of Psychology, 45, 115–122. In order to examine the relationships among various phonological skills and reading comprehension, Latvian children were followed from grade 1 to grade 2 and were tested with a battery of phonological, word reading, and reading comprehension tasks. A principal component analysis of the phonological tasks revealed three salient factors: a phonemic awareness factor, a rapid naming factor, and a short-term memory factor. In order to analyze the relationship between various phonological …
Theoretical and Pragmatic Approaches of Undeclared Work in Romania
2014
Abstract Undeclared work in Romania is a very widespread phenomenon. The published information about the employment relationship worries us, having regard to the damage recorded by undeclared work. For this reason, without claiming a comprehensive approach, through this article we try to give answer to questions such as: What is undeclared work and how it is manifested in Romania? What is the level of undeclared work in Romania? What are the main causes of undeclared work? What measures can be taken to prevent, detect and stop undeclared work? What is the experience of other countries to combat undeclared work?
Correlation analysis of the power law parameters for viscosity of some engineering fluids
2017
Knowledge and estimation of transport properties of fluids which are sensitive to temperature variation like viscosity are necessary in mass flow and heat transfer computation. In the present work,...
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…
The influence of the momentum coefficient and the number of the averaging points of the power spectrum density on the recognition effectiveness of th…
2006
The subject matter of this paper refers to the next stage of the research work connected with the improvement of the acoustic emission method (AE) used for the evaluation of partial discharges (PDs) generated in paper-oil insulation systems of high-voltage power appliances. The subject matter discussed here refers to one of the aspects of the analysis of the signals registered - a correct and effective recognition of the AE signals generated by basic PD forms. The paper presents research results of the application of the unidirectional artificial neuron networks (ANN) used for the recognition of basic PD forms that can occur in paper-oil insulation impaired by aging processes.
A regenerative braking system for internal combustion engine vehicles using supercapacitors as energy storage elements - Part 2: Simulation results
2020
Abstract In this two-part work, an electric kinetic energy recovery system (e-KERS) for internal combustion engine vehicle (ICEV) is presented and its performance evaluated through numerical simulations. The KERS proposed is based on the use of a supercapacitor as energy storage, interfaced to a brushless machine through a properly designed power converter. In Part 1, the system is described and analysed, and the mathematical model used for the simulations is presented. For each component of the KERS, the real efficiency and the power or energy limitations are adequately considered. In Part 2, the energetic and economic advantages attainable by the proposed KERS are evaluated using MATLAB S…
A regenerative braking system for internal combustion engine vehicles using supercapacitors as energy storage elements - Part 1: System analysis and …
2020
Abstract In this two-part work, an electric kinetic energy recovery system (e-KERS) for internal combustion engine vehicle (ICEV) is presented, and its performance evaluated through numerical simulations. The KERS proposed is based on the use of a supercapacitor as energy storage, interfaced to a brushless machine through a properly designed power converter. In part 1, the system is described and analysed, and the mathematical model used for the simulations is presented. For each component of the KERS, the real efficiency, and the power or energy limitations are adequately considered. In part 2, the energetic and economic advantages attainable by the proposed KERS are evaluated using MATLAB…
Towards an AMTEC-like device based on non-alkali metal for efficient, safe and reliable direct conversion of thermal to electric power
2018
Alkali Metal ThermoElectric Converters directly convert heat into electric energy and have promising applicability in the field of sustainable and renewable energy. The high theoretical efficiency, close to Carnot's cycle, the lack of moving parts, and the interesting operating temperature range drive the search for new materials able to ensure safe and reliable operation at competitive costs.The present work focuses on the design of a non-alkali metal based cell and on the fabrication of a testing device to validate the design work. The selection of a new operating fluid for the cell improves durability, reliability and safety of the device. Finally, we discuss possible applications to alr…