Nenad Živković

Assessment of Heavy Metals Pollution in Sediments of the Korbevačka River in Southeastern Serbia

The Korbevačka River is located in the southeastern part of Serbia. This river is a main recipient of all kinds of pollutants from the Pb−Zn mine “Grot.” Sediments from the Korbevačka River were studied to determine the distribution of the metals along the river, assess the quality of sediment, and find the degree of contamination. The concentration of iron, manganese, nickel, copper, zinc, cadmium, lead, mercury, arsenic, chromium, and barium were determined. River sediments were collected and analyzed for heavy metal concentration using atomic absorption spectrophotometer. The degree of pollution in the sediments of the Korbevačka River has been evaluated based on Canadian sediment quality guidelines, enrichment factor (EF), geo-accumulation index (Igeo) and pollution load index (PLI). Inter-metal associations have been evaluated by Pearson correlation coefficients (r). The results indicated that: (1) sediments have been polluted with Pb, Cd, Zn, and Cu and have high anthropogenic influences; (2) the calculation of geo-accumulation index suggests that the Korbevačka River sediments have background concentrations of Fe, Cr, and Ni (Igeo < 1); (3) the co-precipitation (inclusion, occlusion, and adsorption) of heavy metals (except As and Ba) with Mn and Fe geochemical phases.

Testing of Level of Vibration and Parameters of Bearings in Industrial Fan

Climate chambers are a complex system of electromechanical components used for conditioning of air for providing comfort and projected parameters of temperature, humidity, velocity and air cleanliness in the area. In this paper is presented examination of the fan unit company Flaktwoods GJLB-5-071, 17.95 kW, n=1450 rpm, with a multi-functional device Vibrotest 60, the Danish manufacturer Bruel & Kjaer, for diagnostic of parameters of vibration and condition of bearing. The measured parameters are related to: - levels of vibrations (including measurement points on the motor and on the fan) in the directions of coordinate axes, according to ISO 10816-1. - parameters of condition of bearing through the index of bearing condition BCU (Bearing Conditions Unit) and BCS (Bearing Spectrum Conditions) - analysis of the characteristic frequency of vibration in the spectrum, presented by FFT (Fast Fourier Transformation).

Vibration Analysis of Insufficiently Repaired Well Pump - A Case Study

Vibration analysis of the repaired well pump is to determine whether vibrations occur due to an insufficient pump repair or due to some new malfunction that happened after the repair. This paper presents vibration analysis of well pump as well as the applied corrections in order to lower the vibration levels. Vibration measurement of well pump is conducted on measurement points defined by standard ISO 10816-1.

Simulation of hybrid electrical vehicle for two different driving modes

Original scientific paper This paper shows an example of computer simulation of hybrid vehicle in two different driving modes. This example shows multiple areas of operation of a simulated hybrid electric vehicle. The hybrid electric vehicle is of combined type, similar to Toyota Prius cars. This hybrid electric vehicle has two types of driving power: the electric motor and the internal combustion (IC) engine, to increase the level of efficiency of driving assembly and to reduce air pollution. A hybrid electric vehicle combines the advantages of electric motor drive (no pollution and high available power at low speeds) and the advantages of IC engine (high dynamic performances and little pollution at high speeds). In the simulation of a hybrid electric vehicle SimPowerSystemsTM and SimDrivelineTM (MATLAB) were used.