Scardinius knezevici Bianco & Kottelat, 2005 and Alburnus scoranza Bonaparte, 1845: New species of ichthyofauna of Serbia and the Danube basin

Research into the ichthyofauna of the Vlasina Lake reservoir in south Serbia, which is part of the Danube basin, was carried out in 1993, 40 years after its formation. The results of the research reveal the presence of several species of fish belonging to the Adriatic and Aegean basin, such as Alburnus albidus, Rutilus basak, Scardinius graecus and Pachychilon macedonicus. These findings are of great importance from the aspect of conservation, because the species Scardinius graecus and Alburnus albidus are on the European list of endangered fish species. In the latest study of the Vlasina Lake reservoir ichthyofauna (70 years after its formation), the above-mentioned species were not found. However, the presence of naturalized populations of two species from the Adriatic basin were confirmed: Scardinius knezevici and Alburnus scoranza. These findings represent the first known areal expansion of these species, which are new to the ichthyofauna of Serbia, from the Adriatic into the Danube (Black Sea) basin.[Acknowledgments. The present work was supported by the Ministry of Education and Science of the Republic of Serbia (Projects No. 43002 and 173025).

On the possibility of using biological toxicity tests to monitor the work of wastewater treatment plants

The aim of this study was to ascertain the possibility of using biological toxicity tests to monitor influent and effluent wastewaters of wastewater treatment plants. The information obtained through these tests is used to prevent toxic pollutants from entering wastewater treatment plants and discharge of toxic pollutants into the recipient. Samples of wastewaters from the wastewater treatment plants of Kragujevac and Gornji Milanovac, as well as from the Lepenica and Despotovica Rivers immediately before and after the influx of wastewaters from the plants, were collected between October 2004 and June 2005. Used as the test organism in these tests was the zebrafish Brachydanio rerio Hamilton - Buchanon (Cyprinidae). The acute toxicity test of 96/h duration showed that the tested samples had a slight acutely toxic effect on B. rerio, except for the sample of influent wastewater into the Cvetojevac wastewater treatment plant, which had moderately acute toxicity, indicating that such water should be prevented from entering the system in order to eliminate its detrimental effect on the purification process

Scardinius knezevici Bianco & Kottelat, 2005 and Alburnus scoranza Bonaparte, 1845: New species of ichthyofauna of Serbia and the Danube basin

Research into the ichthyofauna of the Vlasina Lake reservoir in south Serbia, which is part of the Danube basin, was carried out in 1993, 40 years after its formation. The results of the research reveal the presence of several species of fish belonging to the Adriatic and Aegean basin, such as Alburnus albidus, Rutilus basak, Scardinius graecus and Pachychilon macedonicus. These findings are of great importance from the aspect of conservation, because the species Scardinius graecus and Alburnus albidus are on the European list of endangered fish species. In the latest study of the Vlasina Lake reservoir ichthyofauna (70 years after its formation), the above-mentioned species were not found. However, the presence of naturalized populations of two species from the Adriatic basin were confirmed: Scardinius knezevici and Alburnus scoranza. These findings represent the first known areal expansion of these species, which are new to the ichthyofauna of Serbia, from the Adriatic into the Danube (Black Sea) basin.Projekat ministarstva br. 43002 i br. 17302

Analysis of diet of piscivorous fishes in Bovan, Gruža and Šumarice Reservoir, Serbia

Diet of adult pikeperch Sander lucioperca, Eurasian perch Perca fluviatilis, northern pike Esox lucius and European catfish Silurus glanis as top predators in aquatic ecosystems in Serbia was investigated during 2011, in order to understand their relationship to their prey and to investigate their food consumption, feeding and assimilation rate, cannibalism, and habitat segregation. Northern pike, Eurasian perch, pikeperch and European catfish were collected in three reservoirs in Serbia. Prey items that were found in all four species included fish, mollusks, insect larvae and crustaceans. A total of 11 taxonomic groups were found, but they were not all represented as a prey in all four species. Eurasian perch were present in the diet of all four predatory fish species, mollusks were recorded only in that of European catfish. Roach Rutilus rutilus and bleak Alburnus alburnus were prey to all species, except northern pike. Chub Squalius cephalus, bream Brama brama and Gammaridae were found only in stomach of pikeperch. Analysis of similarity showed that difference for diet between predatory fish species was significant for their due to significant differences existing between northern pike and pikeperch and northern pike and Eurasian perch

A hybrid genetic optimization method for accurate target localization

U ovom radu, prikazan je TOA (Time of Arrival) model pozicioniranja radi određivanja nepoznate lokacije predajnika. Definisan je kriterijum optimalnosti - funkcija cilja, koja predstavlja sumu kvadrata greške pozicioniranja. Za rešavanje postavljenog optimizacionog modela primenjena je nova metoda GA-NM, koje je bazirana na hibridizaciji Genetskog algoritma i Nelder-Mead metode. Predložena hibridna metoda na efikasan način kombinuje globalnu i lokalnu pretragu datih algoritama kako bi se poboljšale optimizacione performanse i tačnost rešenja. Pored ovoga, u radu je izvedena i Kramer-Rao donja granica CRLB (Cramer-Rao Lower Bound) varijanse procene nepoznate lokacije predajnika za TOA metodu pozicioniranja. Rezultati simulacije pokazuju da predložena hibridna GA-NM metoda postiže značajano poboljšanje performansi u odnosu na postojeće metode.This paper considers the problem of estimating the position of a target based on the time of arrival (TOA) measurements from a set of receivers whose positions are known. The weighted least square (WLS) technique is applied as an efficient existing approach. The optimization problem is formulated by the minimization of the sum of squared residuals between estimated and measured data as the objective function. The hybrid Genetic Algorithm-Nelder-Mead (GA-NM) method is proposed that combines the global search and local search abilities in an effective way in order to improve the performance and the solution accuracy. The corresponding Cramer-Rao lower bound (CRLB) on the localization errors is derived as a benchmark. Simulation results show that the proposed hybrid GA-NM method achieves a significant performance improvement compared to existing methods

Passive Target Localization Problem Based on Improved Hybrid Adaptive Differential Evolution and Nelder-Mead Algorithm

This paper considers a passive target localization problem in Wireless Sensor Networks (WSNs) using the noisy time of arrival (TOA) measurements, obtained from multiple receivers and a single transmitter. The objective function is formulated as a maximum likelihood (ML) estimation problem under the Gaussian noise assumption. Consequently, the objective function of the ML estimator is a highly nonlinear and nonconvex function, where conventional optimization methods are not suitable for this type of problem. Hence, an improved algorithm based on the hybridization of an adaptive differential evolution (ADE) and Nelder-Mead (NM) algorithms, named HADENM, is proposed to find the estimated position of a passive target. In this paper, the control parameters of the ADE algorithm are adaptively updated during the evolution process. In addition, an adaptive adjustment parameter is designed to provide a balance between the global exploration and the local exploitation abilities. Furthermore, the exploitation is strengthened using the NM method by improving the accuracy of the best solution obtained from the ADE algorithm. Statistical analysis has been conducted, to evaluate the benefits of the proposed modifications on the optimization performance of the HADENM algorithm. The comparison results between HADENM algorithm and its versions indicate that the modifications proposed in this paper can improve the overall optimization performance. Furthermore, the simulation shows that the proposed HADENM algorithm can attain the Cramer-Rao lower bound (CRLB) and outperforms the constrained weighted least squares (CWLS) and differential evolution (DE) algorithms. The obtained results demonstrate the high accuracy and robustness of the proposed algorithm for solving the passive target localization problem for a wide range of measurement noise levels

Tribological Aspects of the Process of Winding the Steel Rope Around the Winch Drum

Proper winding of the steel rope around the winch drum is great importance, mostly for: prolonging the service life of the rope, reduction of deformations of the body and the sides of the drum if the winding of the rope is multilayered, increasing of the safety factors, easier unwinding of the rope while lowering the load, even running of the drive unit, etc. The focus of this paper is on the analysis of the friction which occurs in the process of winding and unwinding the rope around the winch drum. Friction force is in its highest intensity when the rope passes from one layer to another, if the winding of the rope is multilayered. As the result of the research, certain mechanisms of winding of the rope from the aspects of the friction force were obtained, and the effects of the forces on the sides of the drum were analyzed

PERMANENT AND SOWN GRASSLANDS IN SERBIA: CURRENT STATE AND TRENDS

Number of cattle in Serbia during two decades of the 21st century shows the tendency of decreasing. The main source for sustainable livestock production in Serbia are grasslands. Permanent grasslands occupy approximately 30% of agricultural land in Serbia, thereby playing an important role in forage production and ecosystem services. The majority of natural meadows and pastures are located in hilly-mountainous regions. The general characteristics of grasslands in the central Balkans are low production and insufficient quality. The yield of permanent grasslands in Serbia is influenced very strongly by climatic conditions, type of grassland and level of organic and mineral fertilization. On areas that are not managed by mowing and fertilizing, forbs make up over half of the plant production.This paper presents some recent experiences and results in livestock feed production obtained from permanent and sown meadows and pastures in Serbia. There is survey of permanent grassland botanical composition and productivity with special emphasis on importance of preserving legume species. Also, recent trials assessed the benefits of mineral and organic fertilizers application in terms of forage production, testing whether the mineral or organic sources improves the stability of the grassland and evaluated response patterns over a large environmental gradient. Nutrient availability in permanent grasslands has a strong influence on plant species biodiversity, plant cover, and species’ dominance in the vegetation canopy. Dry matter yield is very low with high variation in crude protein content, which confirms that grasslands need to be maintained through fertilizer application, with special emphasis being given to the new role of manure enriched by zeolite. The above-stated lead to poor production potential of these grasslands for livestock production, nonetheless offering sustainable means of soil and biodiversity protection in the area

Optimal source localization problem based on TOA measurements

Determining an optimal emitting source location based on the time of arrival (TOA) measurements is one of the important problems in Wireless Sensor Networks (WSNs). The nonlinear least-squares (NLS) estimation technique is employed to obtain the location of an emitting source. This optimization problem has been formulated by the minimization of the sum of squared residuals between estimated and measured data as the objective function. This paper presents a hybridization of Genetic Algorithm (GA) for the determination of the global optimum solution with the local search Newton-Raphson (NR) method. The corresponding Cramer-Rao lower bound (CRLB) on the localization errors is derived, which gives a lower bound on the variance of any unbiased estimator. Simulation results under different signal-to-noise-ratio (SNR) conditions show that the proposed hybrid Genetic Algorithm-Newton-Raphson (GA-NR) improves the accuracy and efficiency of the optimal solution compared to the regular GA

Comparative analysis of the results of theoretical and experimental studies of freight wagon Sdggmrss-twin

This paper presents a comparative analysis based on the results from static strength calculation of wagon body, series Sdggmrss-twin, and on the results from the real wagon test. The verification of results from calculations and tests and their comparison was mandatory for client's commissioning of the wagon by notified body. Calculations based on the finite elements method were carried out in the Department of Railway Engineering at Technical University of Sofia. Experimental studies on real wagon construction were conducted at the facilities of Bulgarian National Transport Research Institute by testing team from Laboratory of rail vehicles at University of Belgrade. It was found that the obtained static stress results are similar, which proves that the proposed models are appropriate and they can help to solve a wide range of issues, for example those related to lightweight design of railway vehicles