THE EFFECT OF FOUR FLAT PLATE REFLECTORS ON LIGHT ENERGY-HARVESTING SYSTEM CHARACTERISTICS

In this paper, the effect of four flat panel reflectors (bottom, top, left and right side reflectors) on the total light radiation on a small-size photovoltaic cell is analyzed. An analytical model for the determination of the optimum inclination angle of the reflectors with respect to the cell’s horizontal surface is presented. The optimal angle was calculated to be 66°. The calculated value was experimentally verified by measuring the short-circuit current of the cell. It was shown that the increase in the short-circuit current of the cell with reflectors in the optimal position was about 60% for the illumination levels between 10 lx and 1000 lx. The cell with reflectors was used to charge the primary capacitor in the energy harvesting circuitry of the wireless sensor node and it was demonstrated that the time needed for the cell to charge the primary capacitor could be reduced 35-40%. UTICAJ ČETIRI RAVNA REFLEKTORA NA KARAKTERISTIKE SISTEMA KOJI SE AUTONOMNO NAPAJA ENERGIJOM SVETLOSTIU radu je analiziran uticaj četiri ravna reflektora (donji, gornji, levi i desni bočni reflektor) na ukupno svetlosno zračenje koje dospeva na solarnu ćeliju malih dimenzija. Dat je analitički model za određivanje optimalnog nagibnog ugla reflektora u odnosu na horizontalnu ravan u kojoj se nalazi solarna ćelija. Izračunati optimalni ugao iznosi 66°. Izračunata vrednost je eksperimentalno proverena merenjem struje kratkog spoja solarne ćelije i pokazano je da povećanje struje kratkog spoja solarne ćelije sa reflektorima u optimalnom položaju iznosi oko 60% za nivo osvetljenosti između 10 lx i 1000 lx. Solarna ćelija je korišćena za punjenje primarnog kondenzatora samonapajajućeg senzora i pokazano je da vreme potrebno za punjenje primarnog kondenzatora može biti smanjeno od 35% do 40%. HIGHLIGHTSThe effect of four flat panel reflectors on the total light radiation on a small-size photovoltaic cell was analyzed;An analytical model for the determination of an optimum inclination angle of the reflectors with respect to the cell’s surface is presented;The optimal inclination angle of the reflectors was determined to be 66°;The reflectors in the optimal position could increase the cell’s short-circuit current up to 60%;The charging time of the primary capacitor was reduced for 35-40%

Influence of reflectance from flat aluminum concentrators on energy efficiency of PV/Thermal collector

In this paper the results of the influence of reflectance from flat plate solar radiation concentrators made of Al sheet and Al foil on energy efficiency of PV/Thermal collector are presented. The total reflectance from concentrators made of Al sheet and Al foil is almost the same, but specular reflectance which is bigger in concentrators made of Al foil results in increase of solar radiation intensity concentration factor. With the increase of solar radiation intensity concentration factor, total daily thermal and electrical energy generated by PV/Thermal collector with concentrators increase. In this work also optimal position of solar radiation concentrators made of Al sheet and Al foil and appropriate thermal and electrical efficiency of PV/Thermal collector have been determined. Total energy generated by PV/Thermal collector with concentrators made of Al foil in optimal position is higher than total energy generated by PV/Thermal collector with concentrators made of Al sheet.PV/Thermal collector Flat solar radiation concentrator

Blood cells in thyroid cancer patients: a possible influence of apoptosis

The side effects of radioactive iodine (131-I) treatment of differentiated thyroid cancer (DTC) patients include reduction of peripheral blood cell counts. The aim of this study was to analyze some potential changes in blood cell counts of DTC patients after 131-I therapy, especially CD3-positive, CD19-positive, and CD56-positive peripheral blood lymphocytes (PBL), as well as the possible role of apoptosis in selected lymphocyte populations. The study group included 24 thyroid cancer patients and 24 control subjects. Peripheral blood samples from patients and controls were analyzed using 5-color flow cytometry. Apoptotic cells were detected using an Annexin V-FITC/7-AAD kit. There was a statistically significant decrease of all blood cells after the 131-I therapy. The CD19+ B lymphocyte population was the most affected (5.82 ± 3.21% before therapy vs. 3.93 ± 2.60% after therapy, p = 0.008). This decrease was correlated with the degree of apoptosis of peripheral blood lymphocytes (Spearman’s r = 0.563, p =0.013). We concluded that 131-I therapy of DTC patients led to a decrease of all peripheral blood cells, especially CD19+ B lymphocytes. This directly correlated with apoptosis of PBLs, indicating that radiation damage to B cells leads to subsequent elimination by apoptosis