Search results for "aurinko"

Thermal performance and microclimate test methods for flat-plate solar thermal collectors

2012

In this Master’s thesis testing methods, experimental setups and data evaluation procedures for flat-plate solar thermal collectors are presented. An official quasi-dynamic test method according to the EU standard EN 12975 for evaluating the collector’s thermal performance is described, and its applicability to an existing experimental setup is evaluated. The general practicality of this setup is also reviewed. Furthermore, a second experimental setup is designed to monitor the inside conditions, or microclimate, of a solar thermal collector, in order to assess the frequency of condensation occurrence inside the collector. This work’s results include that the existing thermal performance se…

A study of solar thermal absorber stack based on CrAlSiNx/CrAlSiNxOy structure by ion beams

2019

Renewable energies are foreseen as a major energy resource for next generations. Among several energy sources and technologies available, Concentrated Solar Power (CSP) technology has a great potential, but it needs to be optimised, in particular to reduce the costs, with an increase of the operating temperature and long term stability. This goal can be achieved by tailoring the composition and multilayer structure of films. In this work we present and discuss the results obtained from solar absorber coatings based on nitride/oxynitride structures. A four-layer film structure, W/CrAlSiNx(HA)/CrAlSiNxOy(LA)/SiAlOx, was deposited on stainless steel substrates using magnetron sputtering deposi…

Boron–nitrogen substituted dihydroindeno[1,2-b]fluorene derivatives as acceptors in organic solar cells

2019

The electrophilic borylation of 2,5-diarylpyrazines results in the formation of boron–nitrogen doped dihydroindeno[1,2-b]fluorene which can be synthesized using standard Schlenk techniques and worked up and handled readily under atmospheric conditions. Through transmetallation via diarylzinc reagents a series of derivatives were synthesized which show broad visible to near-IR light absorption profiles that highlight the versatility of this BN substituted core for use in optoelectronic devices. The synthesis is efficient, scalable and allows for tuning through changes in substituents on the planar heterocyclic core and at boron. Exploratory evaluation in organic solar cell devices as non-ful…

Estimating the flux of the 14.4 keV solar axions

2017

In this paper we present a calculation of the expected flux of the mono-energetic 14.4 keV solar axions emitted by the M1 type nuclear transition of $^{57}$Fe in the Sun. These axions can be detected, e.g., by inverse coherent Bragg-Primakoff conversion in single-crystal TeO$_2$ bolometers. The ingredients of this calculation are i) the axion nucleon coupling, estimated in several popular axion models and ii)the nuclear spin matrix elements involving realistic shell model calculations with both proton and neutron excitations. For the benefit of the experiments we have also calculated the branching ratio involving axion and photon emission

The adoption of photovoltaic micro production systems in Finland

2016

A sustainable supply of energy is one of the most important requirements in order to achieve sustainable development. By using renewable resources society is not dependent on depleting reserves, but instead can have an inexhaustible source of clean energy. The rapid development of photovoltaics has led to lowered prices and increased efficiency making them more attractive alternative as a source of household electricity. Although governments play a key role in setting the constraints of how renewable energy is adopted, the wide-spread adoption of distributed electricity production ultimately depends on consumer decisions to buy them. This study examined the adoption process of photovoltaic …

Aurinkolämpö - teknologia ja mahdollisuudet

2006

Tetrahedral chalcopyrite quantum dots in solar-cell applications

2010

We have considered two different chalcopyrite material combinations suggested for intermediate-band solar cell (IBSC) sample fabrication in Helmholtz Zentrum, Berlin. We have obtained the maximum theoretical efficiency values of these two chalcopyrite IBSCs. The optimal sizes of the chalcopyrite quantum dots (QDs) in the corresponding QD-IBSC implementations have been calculated. Optical absorption spectrum of a single chalcopyrite QD has been obtained for both systems. The effect of the QD geometry, especially the effect of the roundness of the QD, was examined. We hope that these results will help in the quest towards more efficient and more affordable solar cells.

Dark energy, extended gravity, and solar system constraints

2008

Dye molecules on titatium dioxide surface: cluster and periodic surface models

2008

Protecting Young Children Against Skin Cancer : Parental Beliefs, Roles, And Regret

2017

Objective To examine the role of parental beliefs, roles, and anticipated regret toward performing childhood sun-protective behaviours. Methods Parents (N = 230; 174 mothers, 56 fathers), recruited using a nonrandom convenience sample, of at least 1 child aged between 2 and 5 years completed an initial questionnaire assessing demographics and past behaviour as well as theory of planned behaviour global (attitude, subjective norm, and perceived behavioural control) and belief-based (behavioural, normative, and control beliefs) measures, role construction, and anticipated regret regarding their intention and behaviour to protect their child from the sun. Two weeks later, participants complete…