| 1. |
- Abolfathi, Bela, et al.
(författare)
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The Fourteenth Data Release of the Sloan Digital Sky Survey : First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : IOP Publishing Ltd. - 0067-0049 .- 1538-4365. ; 235:2
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Tidskriftsartikel (refereegranskat)abstract
- The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014-2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V.
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| 2. |
- Aguado, D. S., et al.
(författare)
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The Fifteenth Data Release of the Sloan Digital Sky Surveys : First Release of MaNGA-derived Quantities, Data Visualization Tools, and Stellar Library
- 2019
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics Publishing (IOPP). - 0067-0049 .- 1538-4365. ; 240:2
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Tidskriftsartikel (refereegranskat)abstract
- Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 July-2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA-we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020-2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data.
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| 3. |
- Bernardo, Ricardo, et al.
(författare)
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Combined solar and membrane drying technologies for sustainable fruit preservation in low-income countries – prototype development, modelling, and testing
- 2021
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Ingår i: Solar Energy Advances. - : Elsevier BV. - 2667-1131. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- This investigation consisted of developing and evaluating solar dryers together with semi-permeable membrane pouches for drying juicy fruits in low-income tropical countries. Two design iterations were carried out including prototype modelling and testing. The latest developed solar dryers were a passive and an active solar dryer. Modelling was initially carried out mathematically using an equation solver software followed by computational fluid dynamics. Preliminary measurements were carried out on a small-scale solar dryer. Thereafter, full-scale models were developed and tested, both in laboratory and in real conditions in Mozambique. Results from modelling were validated against measurements in laboratory in Sweden and field trials in Mozambique. Prototype building and testing in Mozambique was undertaken in collaboration with local farmers and a university. Measurement results show that the dryers help to prevent microbial growth through increased temperatures. The drying flux was increased by 50% for the passive, and by 100% for the active solar dryers compared to the ambient controls that did not use a solar dryer. The total drying time was below four days for all pouches in the dryers. The active solar dryer was shown to have the shortest drying time and the highest capacity (more pouches) but also the highest costs. Mould growth and juice fermentation were observed on control pouches drying in open air. These problems were solved with the use of solar dryer technology. However, some challenges with the membrane pouches require further development including degradation of the membrane when exposed to direct sunlight.
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| 4. |
- Bernardo, Ricardo, et al.
(författare)
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Evaluation of a Parabolic Concentrating PVT System
- 2008
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Ingår i: Proceedings of the 7th EUROSUN Conference. - 9781617822285
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was testing and performance simulation of an innovative tracking hybrid solar system being developed by the Swedish Company Arontis. The Solar8 collector produces both electrical and thermal energy in one system. Its performance was compared with conventional photovoltaic panels and solar thermal collectors working side-by-side which are already on the market. The solar8 sample tested in Lund is a prototype designed for small demonstration projects and further development is ongoing. The evaluation shows that the thermal collector has an overall heat loss coefficient of 3.1 W/(m2.ºC), an optical efficiency of 65% and an electrical efficiency at 25ºC of 8% per active glazed area. If we account the total glazed area instead, the thermal collector has an overall heat loss coefficient of 2.5 W/(m2.ºC), an optical efficiency of 52% and an electric efficiency at 25ºC of 6%. The electric efficiency of the bare cells is 16%. Annual performance simulations were carried out for the Swedish (Stockholm), Portuguese (Lisbon) and Zambian (Lusaka) climate. From the simulations one can conclude that: Solar8 can be replaced by a traditional PV-thermal collector side-by-side system using less space and producing the same electric and thermal outputs; tracking around one axis placed in North-South direction is considerably better then tracking around an axis set on East-West direction; the global irradiation on a static surface is always higher when compared with the beam irradiation towards a tracking concentrating surface; the ratio between electric and thermal output decreases when Solar8 is moved to the equator.
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| 5. |
- Bernardo, Ricardo, et al.
(författare)
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Measurements of the Electrical Incidence Angle Modifiers of an Asymmetrical Photovoltaic/Thermal Compound Parabolic Concentrating-Collector
- 2013
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Ingår i: Engineering. - : Scientific Research Publishing, Inc.. - 1947-3931 .- 1947-394X. ; 5, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- Reflector edges, sharp acceptance angles and by-pass diodes introduce large variations in the electrical performance of asymmetrical concentrating photovoltaic/thermal modules over a short incidence angle interval. It is therefore important to quantify these impacts precisely. The impact on the electrical performance of the optical properties of an asymmet-rical photovoltaic/thermal CPC-collector was measured in Maputo, Mozambique. The measurements were carried out with the focus on attaining a high resolution incidence angle modifier in both the longitudinal and transversal directions, since large variations were expected over small angle intervals. A detailed analysis of the contribution of the diffuse radiation to the total output was also carried out. The solar cells have an electrical efficiency of 18% while the maxi-mum measured electrical efficiency of the collector was 13.9 % per active glazed area and 20.9 % per active cell area, at 25 °C. Such data make it possible to quantify not only the electrical performance for different climatic and operating conditions but also to determine potential improvements to the collector design. The electrical output can be increased by a number of different measures, e.g. removing the outermost cells, turning the edge cells 90°, dividing each receiver side into three or four parts and directing the tracking, when used, along a north-south axis.
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| 6. |
- Bernardo, Ricardo, et al.
(författare)
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Measurements of the Electrical Incidence Angle Modifiers of an Asymmetrical Photovoltaic/Thermal Compound Parabolic Concentrating-Collector
- 2013
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Ingår i: Engineering. - 1947-394X. ; 5:1B, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- Reflector edges, sharp acceptance angles and by-pass diodes introduce large variations in the electrical performance of asymmetrical concentrating photovoltaic/thermal modules over a short incidence angle interval. It is therefore important to quantify these impacts precisely. The impact on the electrical performance of the optical properties of an asymmetrical photovoltaic/thermal CPC-collector was measured in Maputo, Mozambique. The measurements were carried out with the focus on attaining a high resolution incidence angle modifier in both the longitudinal and transversal directions, since large variations were expected over small angle intervals. A detailed analysis of the contribution of the diffuse radiation to the total output was also carried out. The solar cells have an electrical efficiency of 18% while the maximum measured electrical efficiency of the collector was 13.9 % per active glazed area and 20.9 % per active cell area, at 25 °C. Such data make it possible to quantify not only the electrical performance for different climatic and operating conditions but also to determine potential improvements to the collector design. The electrical output can be increased by a number of different measures, e.g. removing the outermost cells, turning the edge cells 90°, dividing each receiver side into three or four parts and directing the tracking, when used, along a north-south axis.
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| 7. |
- Bernardo, Ricardo, et al.
(författare)
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Performance Evaluation of a High Solar Fraction CPC-Collector System
- 2011
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Ingår i: Journal of Environment and Engineering. - : Japan Society of Mechanical Engineers. - 1880-988X. ; 6:3, s. 680-692
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Tidskriftsartikel (refereegranskat)abstract
- One of the most important goals on solar collector development is to increase the system’s annual performance without increasing overproduction. The studied collector is formed by a compound parabolic reflector which decreases the collector optical efficiency during the summer period. Hence, it is possible to increase the collector area and thus, the annual solar fraction, without increasing the overproduction. Collector measurements were fed into a validated TRNSYS collector model which estimates the solar fraction of the concentrating system and also that of a traditional flat plate collector, both for domestic hot water production. The system design approach aims to maximise the collector area until an annual overproduction limit is reached. This is defined by a new deterioration factor that takes into account the hours and the collector temperature during stagnation periods. Then, the highest solar fraction achieved by both systems was determined. The results show that, at 50° tilt in Lund, Sweden, the concentrating system achieves 71% solar fraction using 17 m2 of collector area compared to 66% solar fraction and 7 m2 of a flat plate collector system. Thus, it is possible to install 2.4 times more collector area and achieve a higher solar fraction using the load adapted collector. However, the summer optical efficiency reduction was proven to be too abrupt. If the reflector geometry is properly design, the load adapted collector can be a competitive solution in the market if produced in an economical way.
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| 8. |
- Bernardo, Ricardo, et al.
(författare)
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Performance evaluation of low concentrating photovoltaic/thermal systems: A case study from Sweden
- 2011
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X. ; 85:7, s. 1499-1510
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Tidskriftsartikel (refereegranskat)abstract
- Some of the main bottlenecks for the development and commercialization of photovoltaic/thermal hybrids are the lack of an internationally recognized standard testing procedure as well as a method to compare different hybrids with each other and with conventional alternatives. A complete methodology to characterize, simulate and evaluate concentrating photovoltaic/thermal hybrids has been proposed and exemplified in a particular case study. By using the suggested testing method, the hybrid parameters were experimentally determined. These were used in a validated simulation model that estimates the hybrid outputs in different geographic locations. Furthermore, the method includes a comparison of the hybrid performance with conventional collectors and photovoltaic modules working side-by-side. The measurements show that the hybrid electrical efficiency is 6.4% while the optical efficiency is 0.45 and the U-value 1.9 W/m(2) degrees C. These values are poor when compared with the parameters of standard PV modules and flat plate collectors. Also, the beam irradiation incident on a north south axis tracking surface is 20-40% lower than the global irradiation incident on a fixed surface at optimal tilt. There is margin of improvement for the studied hybrid but this combination makes it difficult for concentrating hybrids to compete with conventional PV modules and flat plate collectors. (C) 2011 Elsevier Ltd. All rights reserved.
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| 9. |
- Bernardo, Ricardo
(författare)
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Retrofitted Solar Domestic Hot Water System for Single-Family Electrically-Heated Houses: Development and testing
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, there are roughly half a million single family houses that use electric heating for both domestic hot water production and space heating. Since electricity is the most expensive energy source in Sweden, it is interesting to install a high solar fraction solar thermal system to reduce the energy use in these houses. One of the most significant bottlenecks for deployment of solar heating technology is economic profitability due to high investment costs. During this investigation a system that retrofits existing domestic hot water heaters was developed. This has the potential to significantly reduce the investment costs regarding both material and installation. Three different collectors were also tested. Their suitability to be part of the retrofitted solar domestic hot water system was addressed. These were a one-axis tracking photovoltaic/thermal (PV/T) concentrating hybrid and two stationary compound parabolic concentrating (CPC) collectors with the same geometry. One of the CPC collectors was a thermal collector while the other was a PV/T hybrid collector. The aim for PV/T concentrating hybrid collectors is to produce both heat and electricity at a lower cost than conventional alternatives. The CPC-thermal collector design aims to adapt the solar production to the yearly consumption profile in order to achieve a higher annual solar fraction without increasing the stagnation periods. Outdoor measurements were carried out to characterise the collectors. For the retrofitted system, several system configurations were theoretically analysed by means of simulation models using TRNSYS software. A prototype of the retrofitted system was built and the simulation model was revised and validated against measurements. The validated model was further used to optimize the performance of the system and to carry out a sensitivity analysis. Furthermore, an add-on retrofitting unit that is able to connect solar collectors to existing hot water heaters was also designed and built. Measurement results showed that the efficiency values of the tracking concentrating PV/T hybrid are lower than those of conventional flat plate collectors and PV modules. The usable incident irradiation on the one-axis tracking concentrating surface is also lower than the usable irradiation incident on an optimally tilted flat surface. Even though the studied hybrid has potential for improvement, the combination of low efficiencies with low usable irradiation levels makes it difficult for concentrating PV/T hybrids to compete with conventional alternatives, especially in countries where the annual beam irradiation values are low. The geometry of the tested stationary CPC-PV/T hybrid collector was shown not to be the most appropriate for hybrid applications. The studied CPC-thermal collector system was found to achieve a higher annual solar fraction than a conventional flat plate collector system while making use of less absorber surface, one of the most expensive components in the collector. It is concluded that the CPC-thermal collector is adequate to be part of the retrofitting solar domestic hot water system in Swedish single family houses. The decrease in absorber area together with the increase in performance must compensate for the additional cost of extra materials such as reflectors, glass and frames. The investigation of the retrofit system showed that an annual solar fraction of 58 % can be achieved in Sweden when a 200-litre hot water heater is retrofitted and 6 m2 of flat plate collectors is used. The investment cost of the developed retrofit solution was estimated to be reduced by roughly one third compared with a conventional solar domestic hot water system. This means that the developed retrofit system achieves a comparable performance with conventional solar domestic hot water systems in single-family houses with a significant reduction in investment cost. The developed retrofitting solution is therefore considered to have the potential to become a competitive solution in the solar domestic hot water market.
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| 10. |
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