Karakterizacija parametara električnog modela fotonaponskog modula

In terms of PV module electrical energy production management it is important to know how much energy is available at any given time. Electrical load or distributive grid is consuming this produced energy. The electrical model of PV module can be used as a source of information for regulation of energy flow from PV module towards the load or the grid, and not the other way around. There is an optimal load for every operating point of the system, which will consume all of available electrical energy at a given moment. It is necessary to ensure the energy flow through the converter using the converter control system since the load cannot be arbitrarily altered, by setting the operating point of converter to maximum power point (MPP) of PV module. In this paper the influence of single parameter is presented for electrical model of PV module on output characteristic of current and voltage.U smislu upravljanja proizvodnjom električne energije fotonaponskim modulom važno je znati sa koliko energije raspolažemo u određenom trenutku. Električni teret ili distributivna mreža preuzimaju ovako proizvedenu energiju. Električni model fotonaponskog panela može se koristiti kao izvor informacija za regulaciju toka energije od fotonaposnkog panela prema teretu ili mreži, a ne obratno. Za svaku radnu točku sustava postoji optimalno opterećenje koje će preuzeti upravo svu električnu energiju koja je dostupna u tom trenutku. Budući da se opterećenje u većini slučajeva ne može proizvoljno mijenjati potrebno je osigurati tok energije kroz pretvarač upravljačkim sustavom, odnosno postavljanjem pretvarača u radnu točku maksimalne radne snage (MPP) fotonaponskog panela. U ovom članku prikazani su utjecaji promjene pojedinih parametara električnog modela fotonaponskog panela na izlaznu karakteristiku struje i napona

The prevalence of arterial hypertension in civil engineering workers of Slavonia

Na području Slavonije, 1984. godine, sistematski su obrađeni građevinski radnici (eksperimentalna grupa, N = 681) i poljoprivredni radnici (komparativna grupa, N = 877), oba spola, u dobi od 18 do 65 godina. Ispitivana je učestalost arterijske hipertenzije u odnosu na spol i dob. Utvrđena je prevalencija hipertenzije u muškaraca 29,2%, a u žena 32,4%. Utjecaj godina na prevalenciju hipertenzije je dominantan. Tako je u muškaraca do 24 godine prevalencija hipertenzije 6,3%, a u dobi od 55 godina i više, čak 59,2%. Slič­no je i u žena. U odnosu na pojedine kategorije hipertenzije, i u muškaraca i u žena bilo je više dijastoličke hipertenzije (u muškaraca 14,8%, u žena 18,7%) nego miješanog tipa sistoličko-dijastoličke (u muškaraca 11,5%, u žena 10,8%). Sistolička hipertenzija bila je 2,9% u muškaraca i žena. Granična arterijska hipertenzija bila je u muškaraca 14,8%, u žena 17,6%. U komparatiitaioj grupi prevalencija hipertenzije bila je u muškarca 33,0%, a u žena 35,9%.Na području Slavonije, 1984. godine, sistematski su obrađeni građevinski radnici (eksperimentalna grupa, N = 681) i poljoprivredni radnici (komparativna grupa, N = 877), oba spola, u dobi od 18 do 65 godina. Ispitivana je učestalost arterijske hipertenzije u odnosu na spol i dob. Utvrđena je prevalencija hipertenzije u muškaraca 29,2%, a u žena 32,4%. Utjecaj godina na prevalenciju hipertenzije je dominantan. Tako je u muškaraca do 24 godine prevalencija hipertenzije 6,3%, a u dobi od 55 godina i više, čak 59,2%. Slič­no je i u žena. U odnosu na pojedine kategorije hipertenzije, i u muškaraca i u žena bilo je više dijastoličke hipertenzije (u muškaraca 14,8%, u žena 18,7%) nego miješanog tipa sistoličko-dijastoličke (u muškaraca 11,5%, u žena 10,8%). Sistolička hipertenzija bila je 2,9% u muškaraca i žena. Granična arterijska hipertenzija bila je u muškaraca 14,8%, u žena 17,6%. U komparatiitaioj grupi prevalencija hipertenzije bila je u muškarca 33,0%, a u žena 35,9%

Parallel Active Power Filter with Predictive Structure for Reference Current Determination – Experimental System

U svrhu eksperimentalne provjere rezultata simulacije trofaznog aktivnog filtra s prediktivnim određivanjem referentne struje izrađena je njegova laboratorijska maketa. U radu je prikazan funkcionalan opis laboratorijske makete trofaznog aktivnog filtra. Energetski krug aktivnog filtra sastoji se od tri jednofazne prigušnice, trofaznog izmjenjivača s IGBT-ovima i dva simetrična kondenzatora na istosmjernoj strani. Regulacija struje realizirana je pomoću tri neovisna histerezna regulatora. Razrađen je algoritam filtarskog sustava s prediktivnom strukturom za određivanje referentne struje i implementiran na DSP. Prikazani su eksperimentalni rezultati ostvarenog trofaznog aktivnog filtra u stacionarnom i dinamičkom režimu rada. Dobiveni eksperimentalni rezultati potvrđuju učinkovitost aktivnog energetskog filtra pri slabljenju viših harmonika struje u mreži.For the purpose of simulation results testing, a laboratory prototype of three-phase active power filter with predictive structure for reference current determination has been developed. A functional description of the laboratory prototype is presented. Power stage of the proposed active filter has been realized using three serial inductance, three-phase IGBT based current control voltage inverter with two symmetrical capacitors on dc bus. Three independent hysteresis controllers on the base of reference currents were used to generate switching signals for inverter transistors. The algorithm for current reference determination as a combination of digital predictive filter and low pass filter was developed and implemented on DSP controller. The experimental results of three-phase active power filter for stationary and dynamic regimes are presented. Experimental results show that the active power filter gives satisfactory performance in power system harmonic attenuation

Parallel Active Power Filter with Predictive Structure for Reference Current Determination – Experimental System

U svrhu eksperimentalne provjere rezultata simulacije trofaznog aktivnog filtra s prediktivnim određivanjem referentne struje izrađena je njegova laboratorijska maketa. U radu je prikazan funkcionalan opis laboratorijske makete trofaznog aktivnog filtra. Energetski krug aktivnog filtra sastoji se od tri jednofazne prigušnice, trofaznog izmjenjivača s IGBT-ovima i dva simetrična kondenzatora na istosmjernoj strani. Regulacija struje realizirana je pomoću tri neovisna histerezna regulatora. Razrađen je algoritam filtarskog sustava s prediktivnom strukturom za određivanje referentne struje i implementiran na DSP. Prikazani su eksperimentalni rezultati ostvarenog trofaznog aktivnog filtra u stacionarnom i dinamičkom režimu rada. Dobiveni eksperimentalni rezultati potvrđuju učinkovitost aktivnog energetskog filtra pri slabljenju viših harmonika struje u mreži.For the purpose of simulation results testing, a laboratory prototype of three-phase active power filter with predictive structure for reference current determination has been developed. A functional description of the laboratory prototype is presented. Power stage of the proposed active filter has been realized using three serial inductance, three-phase IGBT based current control voltage inverter with two symmetrical capacitors on dc bus. Three independent hysteresis controllers on the base of reference currents were used to generate switching signals for inverter transistors. The algorithm for current reference determination as a combination of digital predictive filter and low pass filter was developed and implemented on DSP controller. The experimental results of three-phase active power filter for stationary and dynamic regimes are presented. Experimental results show that the active power filter gives satisfactory performance in power system harmonic attenuation

Response of sugar beet to soil water deficit

An investigation was carried out at Rimski Sancevi, experiment field of Institute of Field and Vegetable Crops, Novi Sad in the period 2001-2006, aiming to determine the response of sugar beet to soil water deficit, using crop response factor (ky). The values of ky were derived from the linear relationship between relative seasonal evapotranspiration deficits (1-ETa/ETm) and relative yield loss (1-Ya/Ym). Values of crop response factor in the growing period (ky 0.45) indicated that sugar beet is moderately sensitive to soil water stress in the climatic conditions of the Vojvodina Province

Prediction of Soybean Plant Density Using a Machine Learning Model and Vegetation Indices Extracted from RGB Images Taken with a UAV

Soybean plant density is an important factor of successful agricultural production. Due to the high number of plants per unit area, early plant overlapping and eventual plant loss, the estimation of soybean plant density in the later stages of development should enable the determination of the final plant number and reflect the state of the harvest. In order to assess soybean plant density in a digital, nondestructive, and less intense way, analysis was performed on RGB images (containing three channels: RED, GREEN, and BLUE) taken with a UAV (Unmanned Aerial Vehicle) on 66 experimental plots in 2018, and 200 experimental plots in 2019. Mean values of the R, G, and B channels were extracted for each plot, then vegetation indices (VIs) were calculated and used as predictors for the machine learning model (MLM). The model was calibrated in 2018 and validated in 2019. For validation purposes, the predicted values for the 200 experimental plots were compared with the real number of plants per unit area (m(2)). Model validation resulted in the correlation coefficient-R = 0.87, mean absolute error (MAE) = 6.24, and root mean square error (RMSE) = 7.47. The results of the research indicate the possibility of using the MLM, based on simple values of VIs, for the prediction of plant density in agriculture without using human labor

Coenurosis of sheep in Serbia - case report

Coenurosisa is a zoonotic disease caused by the larval forms of Taenia multiceps which are great host's animals from the family of canids. The disease is global distribution but is most present in the Mediterranean, Middle East, Central Africa and Australia. Larvae exhibit tropism toward brain tissue, and cysts are usually located in the left hemisphere of the brain of small ruminants. Involvement of the brain can cause increased intracranial pressure, seizures, loss of consciousness, and focal neurologic deficits. During 2022 we examinee one flocks of 78 milking sheep reared on hilly pastures located below the Zmajevac hill (397 m), between the branches of the Osimćki mountains and the river Zapadna Morava, at an altitude of 178 m. Symptoms of ataxia, such as unsteady gait and stumbling, and depression were observed in 12 animals. In 5 sheep, continuous aimless or circular movement, wandering, was also manifested. In addition to these symptoms, in one sheep that died, visual disturbances were observed depression and unilateral blindness. All affected sheep were slaughtered and a pathoanatomical examination was performed. In the brain of all animals we revealed the presence of infestation with one to four coenuri 4.1-5.5 cm in size. The sites of predilection were the left hemisphere (48%), followed by the right hemisphere (40%) and the cerebellum (12%). The coenurus has a thin wall surrounding a single cavity that contains a clear fluid. When the cysts were opened, numerous scoleces were found inside, from 2 to 3 mm in diameter attached to the cyst wall. Each scolex has four circular suckers and two rows of hooks on a rostellum. The hook lengths are 147 to 165 µm and 87 to 125 µm.The results show that C. cerebralis was a major cause of the nervous manifestations of cenurosis in clinically affected sheep.Proceeding

COENUROSIS OF SHEEP IN SERBIA - CASE REPORT

Coenurosis is a zoonotic disease caused by the larval forms of Taenia multiceps which are great host's animals from the family of canids. The disease is global distribution but is most present in the Mediterranean, Middle East, Central Africa and Australia. Larvae exhibit tropism toward brain tissue, and cysts are usually located in the left hemisphere of the brain of small ruminants. Involvement of the brain can cause increased intracranial pressure, seizures, loss of consciousness, and focal neurologic deficits. During 2022 we examinee one flocks of 78 milking sheep reared on hilly pastures located below the Zmajevac hill (397 m), between the branches of the Osimćki mountains and the river Zapadna Morava, at an altitude of 178 m. Symptoms of ataxia, such as unsteady gait and stumbling, and depression were observed in 12 animals. In 5 sheep, continuous aimless or circular movement, wandering, was also manifested. In addition to these symptoms, in one sheep that died, visual disturbances were observed depression and unilateral blindness. All affected sheep were slaughtered and a pathoanatomical examination was performed. In the brain of all animals we revealed the presence of infestation with one to four coenuri 4.1-5.5 cm in size. The sites of predilection were the left hemisphere (48%), followed by the right hemisphere (40%) and the cerebellum (12%). The coenurus has a thin wall surrounding a single cavity that contains a clear fluid. When the cysts were opened, numerous scoleces were found inside, from 2 to 3 mm in diameter attached to the cyst wall. Each scolex has four circular suckers and two rows of hooks on a rostellum. The hook lengths are 147 to 165 µm and 87 to 125 µm.The results show that C. cerebralis was a major cause of the nervous manifestations of coenurosis in clinically affected sheep

Moguće uštede primenom energetski efikasnih građevinskih materijala za omotače potkrovlјa

Zbog nedostatka stanova, zahvaljujući zakonskim rešenjima koja su to omogućavala, mnogi podstanari su svoje stambeno pitanje rešavali adaptacijom tavanskih prostora, ili nadziđivanjem postojećih zgrada. Nadziđivanja od jednog nivoanajčešće su rađena od drvenih konstrukcija sa minimalnom termičkom izolacijom, najčešće sa jednim slojem od 5 cm mineralne vune i opšivena limom. Slična je situacija i sa adaptiranim stambenim jedinicama u samim krovovima. Takva potkrovlja su prave energetske rupe i najveći potrošači energije. U radu se upoređuju dva tipična potkrovlja na jednoj istoj lokaciji, jedno uređeno savremeno u 2006.godini, sa zadovoljavajućom termičkom zaštitom zidova i svremenim PVC prozorima i drugo uređeno 80-tih godina sa velikim termičkim gubicima. Rezultati su takođe potvrđeni i snimcima dobijenim termovizijskom kamerom