The line graph associated to the total graph of a commutative ring

Let R be a commutative ring with identity and T(Gamma(R)) its total graph. The subject of this article is the investigation of the properties of the corresponding line graph L(T(Gamma(R))). The classification of all commutative rings whose line graphs are planar or toroidal is given. It is shown that for every integer g >= 0 there are only finitely many commutative rings such that gamma(L(T(Gamma(R)))) = g

High-bay warehouse analysis based on influence of stochastic parameters

U radu je analizirana familija visokoregalnih skladišta sa jednim uređajem za opsluživanje. Ciklus rada, kao osnovni element sistema, proračunat je prema FEM propisu sa posebnim osvrtom na promenu brzine kretanja uređaja za opsluživanje u vremenu. Različite teorijske raspodele za modeliranje dolaznog toka, opsluživanja i otkaza su korišćene u radu za određivanje stohastičkog uticaja na performanse skladišnog sistema. Ostali uticaji na performanse skladišnog sistema su obuhvaćeni preko promene opterećenja sistema. Kombinacija oba uticaja i njihova promena dovode do zaključka o stohastičkom ponašanju posmatranih performansi sistema prikazanih preko različitih teorijskih raspodela. Posebno je razvijen simulacioni model koji je korišćen za analizu rada skladišnih sistema.A group of high-bay warehouses with one servicing device is analyzed. Working cycle of servicing device is calculated upon FEM regulation, using optimal change of velocity in time. Different theoretical distributions for arrival rate, servicing flow and failure were used, in this paper, for determining stochastic influence on warehouse system performances. The other influence on warehouse system performances is taken through offered load of the system. Combination of both influences and variety of each brought up the conclusion about stochastic behavior of observed system performances presented by theoretical distributions. Developed simulation model was used for analysis of warehouse system work

Time dependent system state probabilities of single server queuing system with infinite queue

Analitički izraz za verovatnoće stanja u zavisnosti od vremena, jednokanalnog sistema masovnog opsluživanja sa neograničenim redom M/M/1, je izveden. Izraz je izveden nalaženjem granične vrednosti izraza za verovatnoće stanja u zavisnosti od vremena jednokanalnog sistema masovnog opsluživanja sa ograničenim redom M/M/1/K, kada broj mesta u redu teži beskonačnosti, u slučaju kada je sistem na početku rada prazan. Pri izvođenju korišćene su samo elementarne matematičke operacije.Analytical expression for time dependent system state probabilities of single server queuing system with infinite queue capacity M/M/1 is derived. Expression is derived by finding the limit value of expression for time dependent system state probabilities of single server queuing system with finite queue capacity M/M/1/K, when number of places in the queue tens to infinity, in the case that system is empty at the beginning. Only elementary mathematical operations are used

Time dependent system state probabilities of single server queuing system with infinite queue

Analitički izraz za verovatnoće stanja u zavisnosti od vremena, jednokanalnog sistema masovnog opsluživanja sa neograničenim redom M/M/1, je izveden. Izraz je izveden nalaženjem granične vrednosti izraza za verovatnoće stanja u zavisnosti od vremena jednokanalnog sistema masovnog opsluživanja sa ograničenim redom M/M/1/K, kada broj mesta u redu teži beskonačnosti, u slučaju kada je sistem na početku rada prazan. Pri izvođenju korišćene su samo elementarne matematičke operacije.Analytical expression for time dependent system state probabilities of single server queuing system with infinite queue capacity M/M/1 is derived. Expression is derived by finding the limit value of expression for time dependent system state probabilities of single server queuing system with finite queue capacity M/M/1/K, when number of places in the queue tens to infinity, in the case that system is empty at the beginning. Only elementary mathematical operations are used

Determining the Capacity of Unloading Bulk Cargo Terminal Using Queuing Theory

Hierarchical structure of the system, river terminals for bulk cargo unloading, connected with queuing and servicing and stochastic character of the input/output values are underlined. The approach using the queuing theory is developed for engineering use as simpler faster and more convenient than the approach using simulation. Results obtained using the queuing theory and previously obtained results using simulation modelling are shown alongside. The obtained results can be used at the beginning of the design process when rough estimations of the system behaviour are needed. Some of the obtained results are applied and verified on the existing system

Energetski efikasno napajanje autonomnih potrošača korišćenjem hibridnog (fotonaponskog i dizelagregatskog) izvora

The energy efficient solution of autonomous power supply of consumers during the year, by using of a hybrid (photovoltaic and diesel aggregates) sources in the monastery Chilandar is presented in this paper. In details optimal load of diesel aggregate is discussed with a minimum consumption of fossil fuels. The results of the one year exploitation of the electricity generated from photovoltaic panels in our conditions are presented as well. Taking into consideration the specific location and importance of the monastery, the current and future needs of the monastery and particular way of life of the monks, the new hybrid system for the daily consumption of 400 kWh of energy and peak load of 80 kW has been designed and explained. It is based on the combined use of the three diesel power generators 2 x 40 kW and 80 kW, photovoltaic rated power 75 kW and battery pack for energy storage of 400 kWh. The primary objective of the new system is to reduce the consumption of diesel fuel and operating costs for the system power consumption.U ovom radu je opisano energetski efikasno rešenje autonomnog napajanja potrošača tokom godine, korišćenjem hibridnog (solarne i dizel agregata) izvora u manastiru Hilandaru. Detaljnije je razmotreno optimalno opterećenje dizel agregata sa minimalnom potrošnjom fosilnih goriva. Prikazani su rezultati jednogodišnjeg ispitivanja, u našim uslovima, dobijanja električne energije iz fotonaponskih panela. Imajući u vidu specifičnu lokaciju i značaj manastira, sadašnje i buduće potrebe manastira i specifičan način života monaha, nov hibridni sistem za dnevnu potrošnju od 400 kWh električne energije i vršno opterećenje od 80 kW je projektovan i objašnjen. Zasniva na kombinovanom korišćenju tri dizel generatora snage 2 x 40 kW i 80 kW, fotonaponskih nominalne snage 75 kW i baterije za skladištenje energije od 400 kW. Primarni cilj novog sistema je da smanji potrošnju dizel goriva i operativnih troškova za potrošnju energije sistema