Detekcija gasova sa senzorima sa površinskim akustičnim talasom

Abstract Surface Acoustic Wave (SAW) sensors demonstrate superior sensitivity in detection of chemical agents. Due to their solid state design and fabrication compatible with modern technologies, SAW chemical sensors are extremely reliable. The sensor is modeled as a two-port device with parts represented by equivalent circuits. Change of output frequency as a function of vapor concentration is calculated. The oscillator circuit with SAW sensor in the feedback loop is designed. The SAW sensor is used for modifying the oscillator frequency. The presence of chemical vapor is then detected by monitoring this frequency shift

A long-term population study of the Eurasian griffon (Gyps fulvus) in Serbia before and following the establishment of a supplementary feeding program

The Eurasian griffon population in Serbia declined throughout the 20th century from widespread to a rare species, counting a total of 14 detected pairs in two colonies in western Serbia in the 1990s. Although the conservation measures have been implemented since the 1970s, they have had little effect on the further population decline until the supplementary feeding program started in 1989. In this paper, we present the results related to the population trends and reproduction parameters, following the establishment of a supplementary feeding program of the Eurasian griffon in Serbia based on a 34-year survey (1985-2018). By 2018, a total of 2458 tons of supplementary food was provided at three feeding stations. The population increased from 14 detected pairs in two colonies in 1992 to 262 detected pairs in four colonies in 2018. A total of 1807 juveniles were fledged, with breeding success - fledged chicks/laying pairs (i.e., breeding pairs) (0.81 +/- 0.07; mean +/- SD) and productivity - fledged chicks/detected pairs (0.57 +/- 0.10). The amount of supplementary food was in a significant positive correlation with the number of detected and breeding pairs and the number of fledged juveniles. Furthermore, breeding parameters remained high despite the substantial increase in population size, implying that the population is far from saturation level. Our study emphasizes the importance of applied protection measures, especially supplementary feeding. The implementation of appropriate networks of feeding stations and the promotion of free-range livestock farming, as well as returning to the traditional way of disposing of dead cattle, would be a recommendation for future main conservation activities for the Eurasian griffon population in Serbia

First description of movement and ranging behavior of the Griffon vulture (Gyps fulvus) from Serbia using GPS satellite tracking

Understanding the movement pattern and ranging behavior of the Griffon vulture population in Serbia is of great importance for prioritizing conservation action. In 2011, an immature vulture was the first bird to be equipped with a satellite transmitter in Serbia. Our study aims to define the vulture's foraging areas, home ranges, core and basic areas, and to investigate movement patterns across different years and seasons by analyzing satellite telemetry data. We tracked the movements of the vulture for over three years and obtained satellite tracking data for 34 bird-months (1976 GPS fixes) between October 2011 and July 2014. We determined that the overall foraging area of the vulture across the entire study period was 11654.34 km(2). The overall area used by the vulture was larger during spring and summer than during winter periods. Combined ranges across all years identified one basic area and its associated core area around the Uvac colony and nearby feeding site; we identified three core areas in its proximity. This study showed that areas of traditional stock-raising practices are important vulture foraging areas and that supplementary feeding sites have a vital role. Our maps can be used for future planning of vulture conservation measures

Polyaniline thin films in sensors for detection of toxic welding vapors

In this paper the possibilities of applying sensors based on filters with surface acoustic waves (SAW) for the detection of harmful products in welding processes are analyzed. This review discusses the sensing mechanism and configurations of the sensors. The principles of SAW sensors are considered with special emphasis on the application of conducting polyaniline nanocomposites as sensitive thin layers in sensors for the detection of CO, NO2, and COCl2. The literature suggests the use of In2O3 as a dopant for CO and NO2 detection sensors, and ethylenediamine and phenylenediamine in COCl2 sensors. The paper presents original results of modeling of sensors that are designed for detection of CO and NO2 for which there are experimental data in the literature. The results obtained based on this model are in excellent agreement with results from the literature, which shows the validity of modeling. Based on the developed modeling methods, calculations were done for sensors for the detection of these gases in which the structure was the surface of quartz. From these modeling results it can be concluded that the use of the quartz substrate provides better sensitivity. In addition, the quartz sensors are thermally stable.U radu su analizirane mogućnosti primene senzora u čijoj osnovi se nalaze filtri sa površinskim akustičkim talasom (PAT), za detekciju štetnih produkata u procesu zavarivanja. Objašnjeni su principi rada PAT senzora sa posebnim osvrtom na primenu elektroprovodnih polianilinskih nanokompozitnih materijala – polianilin/In2O3 i etilendiamin i fenilendiamin polianilinskih nanokompozita kao osetljivih tankih slojeva za detekciju CO, NO2 i COCl2. Prikazan je deo originalnih rezultata modelovanja PAT senzora koji su namenjeni detekciji pomenutih gasova. Rezultati dobijeni na bazi sopstvenog modela poređeni su sa rezultatima iz literature. Pokazano je da se ovim na činom modelovanja može uspešno odrediti koncentracija štetnih gasova u okruženju

Modelovanje i projektovanje filtara sa površinskim talasima i njihova primena u vojne svrhe

Abstract: U radu su dati osnovni principi rada PAT filtara, materijali i tehnologijeprimenjeni u njihovoj proizvodnji. Posebna pažnja posvećena ješirokoj i raznovrsnoj primeni filtara s površinskim akustičkim talasom uprocesiranju signala, telekomunikacijama i u oblasti hemijskih senzora,sa naglaskom na primene u vojne svrhe. Prikazan je originalni metodkoji su autori razvili za modeliranje i predikciju karakteristika PAT filtara.Mogućnosti ovog metoda su ilustrovane na primeru hemijskih senzoraza detekciju bojnih otrova. Projektovan je i izrađen PAT filtar PATFPO,koji je osnova za hemijski senzor specijalne namene