An Adaptive Neuro-Fuzzy Inference System in Assessment of Technical Losses in Distribution Networks

The losses in distribution networks have always been key elements in predicting investment, planning work, evaluating the efficiency and effectiveness of a network. This paper elaborates on the use of fuzzy logic systems in analyzing the data from a particular substation area predicting losses in the low voltage network. The data collected from the field were obtained from the Automatic Meter Reading (AMR) and Automatic Meter Management (AMM) systems. The AMR system is fully implemented in EPHZHB and integrated within the network infrastructure at secondary level substations 35/10kV and 10(20)/0.4 kV. The AMM system is partially implemented in the areas of electrical energy consumers; precisely, in accounting meters. Daily information gathered from these systems is of great value for the calculation of technical and non-technical losses. Fuzzy logic in combination with the Artificial Neural Networks implemented via the Adaptive Neuro-Fuzzy Inference System (ANFIS) is used. Finally, FIS Sugeno, FIS Mamdani and ANFIS are compared with the measured data from smart meters and presented with their errors and graphs

Frequency and Time Response of Power Plant Grounding System Exposed to Lightning Strike

This paper examines the frequency response of power plant grounding system exposed to the lightning current. Large amount of current generated by the stroke flow in the grounding system of power plant and dissipate in the soil.  The electric and magnetic field generated by such high voltages and currents may cause damage of equipment and may be dangerous for the personnel in power plant.  For the every given frequency obtained using Fast Fourier Transformation (FFT) of lightning current impulse, electromagnetic field theory approach is used to solve Maxell’s equation and compute scalar potential, electric and magnetic field. Also, the influence of the point in which lightning current is diffused in the grounding system is presented. Three dimensional plots of spatial distribution of scalar potential, electric and magnetic field are presented. The time domain response of scalar potential, electric and magnetic field on one profile is also presented

Vertical Fractures of the Tooth Crown With Amalgam Filling

Amalgam se kao restorativni materijal rabi već više od 150 godina. Mehaničko opterećenje može rezultirati dimenzijskim promjenama dovodeći do nastanka rubnih pukotina i fraktura tvdoga zubnog tkiva. Svrha rada bila je utvrditi čestoću i lokaciju takvih fraktura kod zuba s amalgamskim ispunom. Ispitano je 30 ispitanika (21 muškog i 9 ženskog spola) u dobi od 16. do 42. godine. Kliničkim pregledom u 23 od 30 ispitanika (159 zubi) ustanovljene su frakture. Rezultati su pokazali da: 1. 48% fraktura postoji kod primarnih amalgamskih restauracija, 2. frakture su lokalizirane bukalno (31%) i disto-aproksimalno (26%), 3. gotovo polovica ispuna I. i II. razreda ima frakture, 4. najčešće su kod gornjih molara (75%), osobito kod prvoga molara (80%), 5. u 61% ispitanika frakture su locirane disto-aproksimalano, 6. nema statistički znatne razlike između muškoga i ženskoga spola po čestoći fraktura, 7. čestoća fraktura raste s godinama starosti. Frakture su uvjetovane svojstvima amalgama, utjecaju opterećenja na amalgamsku restauraciju i drugim čimbenicima. Ovo ispitivanje navodi nas na zaključak da svaki drugi pacijent s amalgamskim ispunom ima frakturu te je potrebna točna dijagnoza i zamjena ispuna kako bi se spriječila daljnja napuknuća tvrdoga zubnog tkiva.Amalgam has been used as a restorative material for 150 years. Mechanical loading can lead to dimensional changes resulting in marginal gaps and cracking of the hard dental tissue. The aim of this investigation was to locate and find out how often cracks happen with amalgam restorations. On order to determine this 30 examines were examined (21 male and 9 female), aged from 16 to 42 years. Clinical examination resulted in 23 out of 30 examined patients (159 teeth) had cracks. Cracks were drawn on formerly prepared schemes. Results showed that: 1. 48% of cracks were in primary amalgam restorations; 2. cracks were localized buccally (31%) and distally-proximally (26%); 3. nearly half of all Black Class I and II restorations had cracks; 4. cracks were found in upper molars (75%) and especially in first ones (80%); 5. 61% of examines with cracks were distally-proximally; 6. There were no statistically significant differences between male and female examines; 7. Frequency of cracking raises with age. Cracking is bound with properties of amalgam, influence of loading on amalgam restorations and other factors. This investigation lead us to conclude that every second patient with an amalgam restoration had a crack and better diagnosis and repairing is needed to prevent further cracking

Concentrations of manganese and iron in some woody and herbs plants

Heavy metals are the substances that indicate environmental pollution. The plants polluted with heavy metals may endanger natural environment and cause health problems in humans. In our multidisciplinary research of the concentrations of pollutants in forest ecosystems and natural environment in Belgrade, we examined the contents of heavy metals essential for plants but harmful in greater concentrations on a long-term basis. The fact that heavy metals manganese and iron are accumulated in plants to the greatest extent focused our work on determination of the level of concentrations of Mn and Fe in the vegetative parts of 8 plant types on three locations on the Avala Mountain and one location in the centre of the city of Belgrade. The analyses of heavy metals contents in plants were performed by the method of flame atomic absorption spectrophotometry. The examination of the existence of important differences between the average values was performed by implementation of Duncan’s test for the level of significance of 95%. The current contents of heavy metals in plants in the area of the protected natural resource Avala do not represent danger that would presently cause notable damage to forests but show the tendency of the increase of concentrations. Therefore, this issue should be constantly monitored

Morfološko i imunocitohemijsko ispitivanje tumorskih ćelija kod Marekove bolesti

In this paper are described the macroscopic, microscopic and immunophenotypic characteristics of tumors in Marek’s disease (MD). Liver, kidneys, lungs, heart, proventriclus, ovary and nerves of sciatic plexus collected from 20 chickens aged 8 to 24 weeks were examined. Lymphoproliferative enlargement in various organs of focal and diffuse character was found. The affected organs were enlarged, compact and very brittle, irregular in shape, grayish-red or grayish-white and of fatty consistency. Most often characteristic changes were in the spleen, liver, proventriculus and ovary that usually had a compact or ribbed, fatty cauliflower like formation, different in size. On histological examination proliferation of small and medium size lymphocytes, lymphoblast cells, Marek’s disease cells and activated reticulum cells were found. Tumor proliferates predominantly consisted of lymphoblasts and had all the characteristics of a lymphoma. Immunohistochemical analysis revealed that lymphoma cells in MD are of CD3 + phenotype. In liver proliferates numerous CD79+ cells were found perivasculary, which is an interesting finding demanding further research.U ovom radu su opisane makroskopske, mikroskopske i imunofenotipske karakteristike tumora kod Marekove bolesti (MB). Ispitivanjem su bili obuhvaćeni jetra, bubreg, pluća, srce, žlezdani želudac, jajnik i nervi ishijadičnog pleksusa dvadeset pilića starosti između8i24 nedelje. U ispitivanom materijalu ustanovljeno je limfoproliferativno bujanje u različitim organima, fokalnog ili difuznog karaktera, pri čemu su zahvaćeni organi znatno povećani, kompaktni i veoma krti, često nepravilnog oblika, sivocrveni ili sivobeli, slaninastog izgleda. Najčešće i najkarakterističnije su bili promenjeni slezina, jetra, žlezdani želudac, jajnici koji obično predstavljaju kompaktne ili izbrazdane tvorevine poput karfiola, slaninastog izgleda i različite veličine. Histološki, u organima se nalaze proliferati malih i srednjih limfocita, zatim limfoblasta, ćelija Marekove bolesti i aktivisane retikulumske ćelije. Tumorski proliferati su predominantno sastavljeni od limfoblasta i imaju sve karakteristike limfoma. Imunohistohemijskom analizom je ustanovljeno da su ćelije limfoma kod MB predominantno T ćelijskog tipa, CD3 fenotipa. U proliferatu u jetri su nađene i brojne CD79 pozitivne ćelije lokalizovane perivaskularno, što predstavlja interesantan nalaz i zahteva dalja ispitivanja