Impact of different wave parameterisation methods on oil spills

In the graduate thesis we described the process of emulsification of spilled oil. Numerical models are\ud used for simulating the process. We used the EMU model, a simple program for determining the stability\ud of emulsion and time of the emulsification processes. In the original model only the Bretschneider\ud method was used for calculating the wave height. Since this method overestimates the wave height, the\ud original EMU model was modified by adding four other methods for calculating the wave height: Seck\ud – Hong method, method CEM, and SMB methods for deep and shallow water. We compared the results\ud of all applied methods for calculating the wave height, emulsification time of Cook Inlet – Granite Point\ud oil, performed with all methods using different input parameters. The results are presented as tables and\ud graphs. We concluded that the choice of wind parameterization method is an important factor in\ud determining the time of the emulsification processes, particularly when simulating spills of light oils

Scrambling time from local perturbations of the rotating BTZ black hole

In this paper, we investigate the entanglement entropy of the rotating BTZ black hole perturbed by a massive back-reacting free falling particle. Then, mutual information between two finite intervals in two asymptotic regions of rotating BTZ is derived. It allows us to find the scrambling time, the time scale in which mutual information vanishes. We give a dual large $c$ CFT description in terms of a thermofield double state with different temperatures for left and right moving modes that is perturbed by a local operator. Exact matching between gravity and CFT results is obtained.Comment: 20 pages, 3 figure

Rectified ethanol production cost analysis

This paper deals with the impact of the most important factors of the total production costs in bioethanol production. The most influential factors are: total investment costs, price of raw materials (price of biomass, enzymes, yeast), and energy costs. Taking into account these factors, a procedure for estimation total production costs was establish. In order to gain insight into the relationship of production and selling price of bioethanol, price of bioethanol for some countries of the European Union and the United States are given

Interactive approach for the sustainable stormwater management in medium-sized cities in Serbia – case study Pancevo

In the Republic of Serbia, stormwater systems are managed by the municipal public utility companies. Due to the political, economic and sociological situation in the last 25 years, development was not continuous, resulting in the numerous issues that need to be addressed. Most of them are related to the socio-economic aspects, capacity building and data. Example problems and viable solutions, for achieving sustainable management by public or private utility companies, are presented through the case study of city of Pancevo

Techno-economic evaluation of residue exhaustion in batch rectification ethanol production plant

This paper presents the techno-economic optimization of batch plant for production of rectified alcohol based on the concentration of ethanol in residue. The aim of the analysis was to determine the extent to which it is economically profitable to exhaust the residual liquid in boiler. The "profit production" criterion is used for calculations

Modeliranje sezonskih promena temperature vode akumulacije Ćelije

This paper presents the results of measurements and numerical modeling of water temperature changes in reservoir Celije in the period from April to October 2012. Reservoir Celije on the river Rasina, for many years attracts the attention of the general public and researchers, due to the importance of water management and impact of wastewater from the upper part of the basin. Reservoir Celije is a major source of PUC Krusevac Waterworks, but is also the recipient of municipal and industrial wastewater from the municipalities of Brus and Blace. Paper uses a two-dimensional model (CE QUAL W2), with transverse averaged hydrodynamic equations for the velocity and temperature field modeling in the vertical longitudinal plane. Data on the water temperature were collected in the field sampling campaigns, using multi - parameter probes. Model calibration enabled good comparison of measured and calculated temperatures, with average absolute deviation of about 0.7oC. For enhanced model performance, it would be necessary to reduce the uncertainty of the input data, which can be achieved by re- commissioning of the measuring station Ravni (upstream of the reservoir) and setting automatic weather station in the vicinity of the barrier.U radu je dat prikaz rezultata merenja i modeliranja sezonskih promena temperature vode u akumulaciji Ćelije u periodu od aprila do oktobra 2012. godine. Akumulacija Ćelije na Rasini, već duži niz godina privlači pažnju šire javnosti i istraživača, obzirom na vodoprivredni značaj i stepen ugroženosti otpadnim vodama iz gornjeg dela sliva. Akumulacija Ćelije je glavno izvorište kruševačkog vodovoda, ali je ujedno i recipijent komunalnih i industrijskih otpadnih voda iz opština Brus i Blace. U radu je korišćen dvodimenzionalni model (CE QUAL W2), sa poprečno osrednjenim hidrodinamičkim jednačinama za modeliranje polja brzina i polja temperatura u vertikalnoj podužnoj ravni. Podaci o temperaturi vode su prikupljeni u kampanjama terenskih merenja, primenom multiparametarskih sondi. Kalibracijom modela, postiglo se dosta dobro poklapanje izmerenih i izračunatih temperatura, sa prosečnim apslutnim odstupanjem od oko 0,7oC. Za unapređen učinak modela, potrebno bi bilo smanjiti neodređenost ulaznih podataka, što bi se postiglo ponovnim puštanjem u pogon merne stanice Ravni (uzvodno od akumulacije) i postavljanjem kompletne automatske meteorološke stanice u blizini pregradnog profila

Modeliranje dvofaznog strujanja (vode i vazduha) nakon utiskivanja vazduha u vodu

One of available lake restoration technologies is injection of compressed air or oxygen into a hypolimnion, promoting vertical mixing of water and dissolution of oxygen. A numerical model has been developed for simulation of bubble flow, with consideration of gas compressibility and oxygen dissolution. Developed model is intended to be utilized for simulation of lakes DO recovery. Model is firstly verified by simulation of bubble flow experiments, reported in the literature, where very good quantitative and qualitative agreement between measured and simulated results is observed. Both flow configurations are tested: in which steady state is achieved, and where steady conditions can not develop. In the second part, model is applied for simulation of conducted experiments where oxygen dissolution has been considered. The paper presents simulation results, where good agreement of simulated and measured quantities is observed.Jedna od raspoložovih tehnologija za poboljšanje kvaliteta vode u jezerima i akumulacijama predstavlja utiskivanje vazduha, odnosno kiseonika, u dublje slojeve vode (hipolimnion), čime se podstiče mešanje vode po vertikalnoj osi i ostvaruje transfer kiseonika iz gasne faze u vodu. U radu se prikazuje razvijeni 3D numerički model za simulaciju dvofaznog strujanja gasa i vode, kojim su obuhvaćeni i uticaji stišljivosti vazduha, kao i transfer mase između vazduha i vode. Model je najpre verifikovan simulacijom nekoliko eksperimenata iz literature, gde su poređeni podaci o distribuciji vazduha i brzine vode nakon utiskivanja vazduha u vodom ispunjen sud sa rezultatima simulacije. Pri tome, simulirani su uslovi strujanja gde se postiže kvazi-ustaljeno strujanje, kao i eksperimenti u kojima takvo strujanje ne može da se ostvari. U drugom delu, model je korišćen za simulaciju sprovedenih eksperimenata u kojima je osmatran porast koncentracija rastvorenog kiseonika tokom utiskivanja vazduha. U radu se prikazuju rezultati ovih simulacija, gde se mogu konstatovati zadovoljavajuća slaganja izmerenih i sračunatih veličina

Interactive approach for the sustainable stormwater management in medium-sized cities in Serbia – case study Pancevo

In the Republic of Serbia, stormwater systems are managed by the municipal public utility companies. Due to the political, economic and sociological situation in the last 25 years, development was not continuous, resulting in the numerous issues that need to be addressed. Most of them are related to the socio-economic aspects, capacity building and data. Example problems and viable solutions, for achieving sustainable management by public or private utility companies, are presented through the case study of city of Pancevo