This paper elaborates on an algorithm for finding the optimal size of a photovoltaic (PV) system of a prosumer based on economic factors. The proposed algorithm was developed in the MATLAB ...programming language and is applied to the Croatian case study considering the Croatian legislation regarding prosumers. The proposed algorithm uses load profile, solar radiation, external temperature and PV module technical characteristics as input data. The algorithm considers the impact of electricity generated from the prosumer’s PV system on the price that the prosumer will receive for the energy exported to the grid as well as achieved savings to calculate the economic indicators — Levelized Cost of Electricity (LCOE), Return on Investment (ROI) and Net Present Value (NPV). Based on the calculated economic indicators LCOE, ROI, and NPV, the optimal size of the PV system is selected. The proposed algorithm was applied to two profiles of prosumers (household and industrial) to demonstrate its usefulness. Furthermore, the impact of the time step of input data on the results has been also investigated. Finally, the proposed algorithm is applied to the input data with 15- and 60-minute time steps for the household prosumer and for the industrial prosumer to obtain the optimal size of the PV system considering the calculated economic indicators.
•Optimal sizing of PV systems based on economic indicators.•The resolution of the input data does not over-affect the economic indicators.•Applications of the proposed algorithm to households and industry.•Industrial consumers have a shorter return on investment.•Estimates of PV power production concerning technical and external influences.
This paper presents a method for finding an optimal photovoltaic (PV) system according to Croatian legislation. The PV sizing model, in which a decision on investment is made according to economic ...indicators, is made using MATLAB Software. Based on the input data, the monthly PV system production is calculated, and electricity price formed. According to the PV system production and electricity price, economic indicators are calculated and obtained as output data. The model input data are solar irradiation, load diagram, PV system costs and market price of electricity while the model output data are PV system production, savings, profit, incomes, Net Present Value (NPV) and Levelized Cost of Electricity (LCOE). The obtained economic indicators are presented graphically and used for decision making on an optimal PV system size. The presented model is applied and presented in a case study.
Battery energy storage technologies overview Šimić, Zvonimir; Topić, Danijel; Knežević, Goran ...
International journal of electrical and computer engineering systems,
04/2021, Letnik:
12, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Battery technologies overview for energy storage applications in power systems is given. Lead-acid, lithium-ion, nickel-cadmium, nickel-metal hydride, sodium-sulfur and vanadium-redox flow batteries ...are overviewed.
Description, graphical representation, advantages and disadvantages as well as technical characteristics are given for all technologies. Differences and similarities between different battery technologies are perceived. Battery technologies are considered with respect to peak shaving, load leveling, power reserve, integration of renewable energy, voltage and frequency regulation and uninterruptible power supply applications. According to technical characteristics for overviewed technologies, comparison between battery storage technologies is given through diagrams which are uniformed. Comparison is done according to specific power, specific energy, power density, energy density, power cost, energy cost, lifetime, lifetime cycles, cell voltage and battery technology efficiency.
Samoregulacija učenja aktivno je participiranje u procesu učenja te podrazumijeva kognitivne, metakognitivne i bihevioralne procese koji obuhvaćaju strategije učenja i suradničko učenje. U osnovi je ...samoregulacije motivacija, koja se u školskim uvjetima može specifičnije odrediti u terminima ispitne anksioznosti, samoefikasnosti i intrinzične te ekstrinzične vrijednosti. Cilj je ovog istraživanja bio provjeriti postoji li razlika izmeðu muških i ženskih sudionika te izmeðu učenika petih i sedmih razreda u intrinzičnoj i ekstrinzičnoj vrijednosti, samoefikasnosti, ispitnoj anksioznosti, strategijama učenja i suradničkom učenju. Sudionici su bili učenici petih i sedmih razreda (N = 172) iz dviju osnovnih škola u Hrvatskoj. Nisu pronaðene razlike izmeðu muških i ženskih sudionika u intrinzičnoj i ekstrinzičnoj vrijednosti, samoefikasnosti, strategijama učenja i suradničkom učenju. Meðutim, rezultati su pokazali statistički značajne razlike u svim navedenim varijablama izmeðu mlaðih i starijih učenika. Slabija motivacija i samoregulacijsko učenje kod starijih učenika potvrðuju dosadašnja istraživanja na ovom području. Rezultati se promatraju u okviru razvoja ličnosti i teorije samoodreðenosti koja opisuje akademsku motivaciju, a time i samoregulaciju učenja.
A microgrid is a part of a distribution grid that can operate connected to the main grid and independent from the main grid. There are AC microgrids, DC microgrids, and hybrid AC-DC microgrids. The ...difference between these three topologies is the number of AC-DC converters. Modeling and simulation of these three main microgrid topologies and a comparison of simulation results are presented in this paper. The microgrid model consists of the photovoltaic power plant, wind turbine, battery energy storage, and two loads. Simulation results are presented so microgrid topologies can be compared and the most suitable topology can be selected.
Self-regulated learning is an active participation in a learning process, which comprises cognitive, metacognitive and behavioural processes, and involves learning strategies and peer learning. In ...the basis of self-regulation is motivation, which in school settings can be specified as test anxiety, selfefficacy, and intrinsic and extrinsic value. The aim of this research was to verify the differences between male and female participants as well as between fifth- and seventh-grade
students, regarding intrinsic and extrinsic value, self-efficacy, test anxiety, learning strategies and peer learning. Participants were fifth-
and seventh-grade students (N = 172) from two elementary schools. No differences were found between male and female participants in intrinsic
and extrinsic value, self-efficacy, learning strategies and peer learning. However, statistically significant differences in the all of the above-mentioned variables were found between younger and older students. Weaker motivation and self-regulated learning, found among older students, confirmed previous findings in this field. Results are discussed within the framework of personality development and selfdetermination theory which describe academic motivation and self-regulated learning.
Samoregulacija učenja aktivno je participiranje u procesu učenja te podrazumijeva kognitivne, metakognitivne i bihevioralne procese koji obuhvaćaju strategije učenja i suradničko učenje. U osnovi je samoregulacije motivacija, koja se u školskim uvjetima može specifičnije
odrediti u terminima ispitne anksioznosti, samoefikasnosti i intrinzične te ekstrinzične vrijednosti. Cilj je ovog istraživanja bio provjeriti postoji li razlika između muških i ženskih sudionika te između učenika petih i sedmih razreda u intrinzičnoj i ekstrinzičnoj vrijednosti, samoefikasnosti, ispitnoj anksioznosti, strategijama učenja
i suradničkom učenju. Sudionici su bili učenici petih i sedmih razreda (N = 172) iz dviju osnovnih škola u Hrvatskoj. Nisu pronađene razlike između muških i ženskih sudionika u intrinzičnoj i ekstrinzičnoj vrijednosti, samoefikasnosti, strategijama učenja i suradničkom učenju. Međutim, rezultati su pokazali statistički značajne razlike u svim navedenim varijablama između mlađih i starijih učenika. Slabija motivacija i samoregulacijsko učenje kod starijih učenika potvrđuju dosadašnja istraživanja na ovom području. Rezultati se promatraju u okviru razvoja ličnosti i teorije samoodređenosti koja opisuje akademsku
motivaciju, a time i samoregulaciju učenja.
La autorregulación del aprendizaje representa una participación activa en el proceso de aprendizaje y supone procesos cognitivos, metacognitivos y conductuales que abarcan estrategias del aprendizaje y aprendizaje colaborativo. En la base de la autorregulación está la motivación que se puede determinar en condiciones escolares más específicamente en términos de ansiedad causada por los exámenes, autoefectividad y valores tanto intrínsecos, como extrínsecos. El objetivo de este trabajo fue verificar si hay alguna diferencia entre los participantes masculinos y femeninos, y entre los alumnos de la quinta y la séptima clase, cuando se trata de valores intrínsecos y extrínsecos, autoefectividad, ansiedad causada por los exámenes, estrategias del aprendizaje y aprendizaje colaborativo. Los participantes fueron alumnos de la quinta y la séptima clase (N = 172) de dos escuelas primarias. No se han detectado diferencias entre los participantes masculinos y femeninos en cuanto a los valores intrínsecos
y extrínsecos, autoefectividad, estrategias del aprendizaje y aprendizaje colaborativo. Sin embargo, los resultados demostraron diferencias estadísticamente significativas en todas las variables enumeradas entre los alumnos mayores y menores. Motivación más débil y aprendizaje autorregulativo en alumnos mayores confirman los hallazgos de investigaciones existentes en este campo. Los resultados se discuten en el marco de desarrollo de personalidad y teoría de autorregulación que describe la motivación académica y en consecuencia la autorregulación del aprendizaje.
Self-regulated learning is an active participation in a learning process, which comprises cognitive, metacognitive and behavioural processes, and involves learning strategies and peer learning. In ...the basis of self-regulation is motivation, which in school settings can be specified as test anxiety, selfefficacy, and intrinsic and extrinsic value. The aim of this research was to verify the differences between male and female participants as well as between fifth- and seventh-grade students, regarding intrinsic and extrinsic value, self-efficacy, test anxiety, learning strategies and peer learning. Participants were fifth- and seventh-grade students (N = 172) from two elementary schools. No differences were found between male and female participants in intrinsic and extrinsic value, self-efficacy, learning strategies and peer learning. However, statistically significant differences in the all of the above-mentioned variables were found between younger and older students. Weaker motivation and self-regulated learning, found among older students, confirmed previous findings in this field. Results are discussed within the framework of personality development and selfdetermination theory which describe academic motivation and self-regulated learning.
Southeast Europe (SEE) is a very important maize-growing region, comparable to the Corn belt region of the United States, with similar dent germplasm (dent by dent hybrids). Historically, this region ...has undergone several genetic material swaps, following the trends in the US, with one of the most significant swaps related to US aid programs after WWII. The imported accessions used to make double-cross hybrids were also mixed with previously adapted germplasm originating from several more distant OPVs, supporting the transition to single cross-breeding. Many of these materials were deposited at the Maize Gene Bank of the Maize Research Institute Zemun Polje (MRIZP) between the 1960s and 1980s. A part of this Gene Bank (572 inbreds) was genotyped with Affymetrix Axiom Maize Genotyping Array with 616,201 polymorphic variants. Data were merged with two other genotyping datasets with mostly European flint (TUM dataset) and dent (DROPS dataset) germplasm. The final pan-European dataset consisted of 974 inbreds and 460,243 markers. Admixture analysis showed seven ancestral populations representing European flint, B73/B14, Lancaster, B37, Wf9/Oh07, A374, and Iodent pools. Subpanel of inbreds with SEE origin showed a lack of Iodent germplasm, marking its historical context. Several signatures of selection were identified at chromosomes 1, 3, 6, 7, 8, 9, and 10. The regions under selection were mined for protein-coding genes and were used for gene ontology (GO) analysis, showing a highly significant overrepresentation of genes involved in response to stress. Our results suggest the accumulation of favorable allelic diversity, especially in the context of changing climate in the genetic resources of SEE.
Phenolic acids (PAs) are a dominant group of phenolic compounds in cereals, existing mostly bound to compounds of cell wall. In this study, a total of 25 cereal grain samples, including wheat, winter ...and spring barley, corn, and popcorn, were evaluated for bound PAs and antioxidant activity in a two-year field trial. The PA contents, determined by HPLC, were significantly affected by cereal type. The mean total PA content was highest in popcorn and corn (3298 and 2213 μg/gdm, respectively), followed by winter and spring barley (991 and 908 μg/gdm, respectively) and wheat (604 μg/gdm). Ferulic acid was the most abundant, accounting from 62% to 83% of total PAs (in popcorn and winter and spring barley, respectively). Across cereals, p-coumaric (35–259 μg/gdm) and p-hidroxybenzoic (45–79 μg/gdm) were also dominant, while in corn and popcorn o-coumaric (71 and 89 μg/gdm, respectively) also occurred in higher content. The mean total phenol content ranged from 853 μg GAE/gdm (wheat) to 1403 μg GAE/gdm (winter barley) with DPPH scavenging activity from 14% to 67%, respectively. A significant influence of crop years on the ferulic acid and total PA content was found, while the variability of other PAs was dependent on the cereal type. The results indicated a high health benefit potential of selected cereals.
Genotype-dependent responses of apples to drought stress were evaluated between commercial and traditional apple cultivars. The results indicate different mechanisms of tolerance to investigated ...drought stress conditions. Chlorophyll fluorescence induction (OJIP) parameters, chlorophyll and carotenoid content, malondialdehyde (MDA), hydrogen peroxide (H
O
), proline, phenols and leaf water content (WC) were measured. The traditional cultivar "Crvenka" confirmed the best tolerance to a drought stress condition, presenting higher photosynthetic efficiency, higher leaf water content, higher levels of chlorophyll content and lower lipid peroxidation with greater membrane stability. The commercial cultivar "Golden Delicious Reinders" showed decreased water content in leaves, increased lipid peroxidation levels and photoinhibition. Considering all results, the commercial cultivar "Golden Delicious Reinders" was adversely affected by drought, while traditional cultivars exhibited better tolerance to drought stress.
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