Search results for "Principle"

Performance evaluation of directly photovoltaic powered DC PM (direct current permanent magnet) motor – propeller thrust system

2013

Photovoltaic (PV) powered directly coupled electro-mechanical system has wide applications (e.g. PV powered cooling fans in green houses, PV water pumping system, solar vehicles). The objective of this work is to analyse the operation of directly PV powered DC PM (direct current permanent magnet) motor – propeller system for selection of motor parameters. The performance of such system mainly depends on the incident solar radiation, operating cell temperature, DC motor and propeller load parameters. It is observed that the operating points of the PV DC PM motor – propeller system matches very closely with the maximum power points (MPPs) of the PV array, if the DC PM motor – propeller parame…

A new modified Inc-Cond MPPT technique and its testing in a whole PV simulator under PSC

2015

In this paper a new modified Inc-Cond MPPT technique able to lead PV plants to work in the real MPP (Maximum Power Point) under PSC (Partial Shading Condition) is proposed. The new Inc-Cond MPPT technique working principle is fully explained, discussed and then successfully tested in a whole and reliable PV simulator conceived and set-up by the Authors in order to test and compare several new MPPT algorithms. The simulation results show that the proposed Inc-Cond MPPT technique is able to successfully lead the PV plant to work in the real MPP both in the cases of instantaneous and gradual changing of shading and of temperature conditions.

Standard testing of photovoltaic modules for use in renewable energy education

2015

A photovoltaic laboratory exercise has been devised and used in the educational curriculum of the Renewable Energy Programme at the University of Jyväskylä. The purpose of the experimental tasks is to give students of renewable energy a good understanding of standard testing procedures used in industry for characterising photovoltaic modules and to provide practical skills in sizing simple photovoltaic installations. Herein the experimental set-up, basic theory and measurement procedure are described. The experimental apparatus is simple to assemble and uses both standard laboratory equipment and recycled components. From the experimental results, the tested PV cell had a maximum efficiency…

Achieving maximum power transfer in a multi-source renewable system

2014

In this paper, a multi-source DC-DC power system is proposed for renewable applications. A multi-input, single inductor power converter controlled by two interacting control loops is designed. The steady-state and small-signal analysis of the designed system is carried out. A battery-photovoltaic system is designed as an application example. Both the output voltage and maximum power point of solar panels are properly controlled to achieve high performances of the whole system. Experimental results on a 48 V laboratory prototype are presented to discuss system performances.

A novel implicit correlation for the operative temperature of a PV panel

2012

Abstract The operating temperature of a commercial PV panel strongly affects the electric power output of the devices. The prediction of the operating temperature therefore plays a central role in the economic and energy assessment of PV systems. The authors propose a new implicit correlation that takes into account the standard weather variables but also the regimen of PV panel in terms of the proximity to the maximum power points. Data coming from an experimental setup were processed by using the least squares technique. To validate the reliability of the correlation, a comparison between expected values and data from other common correlations were done. The results show that the regimen …

Researches Regarding the Use of Elctrohydraulic Servosystems at Industrial Robots

2012

This paper presents some researches regarding the use of electro-hydraulic servo-systems in driving the industrial robots, taking into consideration the conditions in which the robots work. The researches conducted upon a particular system, reveal the optimum design elements for obtaining a good behaviour in use, subsequently a good stability in use.

End-to-End Quality of Service Support

2005

Still Going “Grey” After All These Years? Export Restraint Agreements and the WTO

2013

This chapter assesses how the dual strategy that aimed to eliminate "grey area" measures has worked out in practice, also in the light of the protectionist pressures unleashed by the current economic crisis. After providing a brief overview of the historic proliferation of these measures, it discusses whether the attempt to render ordinary safeguard measures a more attractive alternative to voluntary restraint agreements (VRAs) has worked in practice. The chapter analyses some of the intrinsic and extrinsic weaknesses of the ban itself. The chapter reviews some cases of export-restraint agreements arguably falling within the exceptions to the ban enshrined in Art. 11.1.C. This work has exam…

Comparative Analysis of Four New Alternative Types of Roundabouts: “Turbo”, “Flower”, “Target” and “Four-Flyover” Roundabou

2016

Analysis of literature shows that “modern roundabouts” nowadays exist in all European countries, as well as in more than 60 countries elsewhere in the world. Nowadays, a growing number of studies, presented in scientific and professional literature, point out a poor traffic safety characteristics of “standard” two-lane roundabouts and lower capacity then was expected. These problems are resolved in more ways in different countries; however the solution, whereby the number of conflict spots is diminished has proven to be the most successful. Lower number of conflict spots is one of characteristics of the alternative types of roundabouts. The alternative types of roundabouts are usually more …

Developing a Pedagogical Framework and Design Principles for STEM Learning Environment Design

2020

The need for effective and attractive learning environments (LEs) for science, technology, engineering, and mathematics (STEM) has been internationally recognized. Additionally, the connection between STEM learning and cross-curricular skills such as creativity, innovation, and entrepreneurship has garnered attention. A deep theoretical and empirical understanding is required when designing STEM LEs. In this study, a pedagogical framework for STEM LEs has been developed based on feedback from students, aged 10–18 years old, teachers, school directors, parents, and STEM professionals, and supported by the literature. First, representatives of key stakeholder groups in Belarus, Finland, Germa…