<p>Istraživanja u okviru ove disertacije su usmerena ka određivanju parametara korelacije izbora aktuatora i vremena ciklusa proizvodnje. Dobijeni parametri se koriste kao ulazni elementi metode koja će biti implementirana u softverski paket. Verifikacija predložene metode je izvršena na studijama slučajeva: IML robota i manipulatora za mašinu za termoformiranje, koje predstavljaju odgovarajuće primere uređaja u koje se ugrađuju svi tipovi aktuatora.</p> / <p>Research within this thesis are focused on determining the parameters of correlation election of an actuator and a production cycle time. The resulting parameters are used for the development of appropriate methods that will be implemented in the software package. Verification of the proposed method is performed on case studies: IML robots and manipulators for thermoforming machine, which are appropriate examples of devices that incorporate all types of actuators.</p>

<p>Cilj ovog rada je bio de se utvrdi uticaj brzog vazdu&scaron;nog hlađenja polutki (na &ndash;31&deg;C do cca 4 sata, a zatim na 2 do 4&deg;C do 8, odnosno do 24 sata post mortem), vremena otko&scaron;tavanja post mortem (8 i 24 sata post mortem), nakon brzog hlađenja, i postupka salamurenja (bez ili sa vakuumom) proizvedenog svinjskog mesa (M. semimembranosus) na kvalitet i bezbednost kuvane &scaron;unke (konzervi od mesa u komadima), odnosno postavljen je zadatak razvoja novog proizvodnog procesa kuvane &scaron;unke koji će počivati na značajnoj racionalizaciji tehnolo&scaron;kog postupka, a čime bi se ostvarila i određena ekonomska dobit, uz postizanje vrhunskog kvaliteta proizvoda.<br />Da bi ovako postavljeni zadatak dao očekivane rezultate najpre je ispitan uticaj brzog hlađenja polutki i vremena otko&scaron;tavanja post mortem, nakon brzog hlađenja, na tehnolo&scaron;ki, nutritivni i senzorni kvalitet i bezbednost svinjskog mesa (M. semimembranosus), namenjenog proizvodnji ovog proizvoda. Analizom dobijenih rezultata zaključeno je da se brzim hlađenjem može obezbediti otko&scaron;tavanje polutki 8 sati post mortem, sa internom temperaturom manjom od 7&deg;C, uz značajno smanjenje tro&scaron;kova rada, kala hlađenja i udela mesa (M. semimembranosus) blede boje, odnosno zaključeno je da su brzo hlađeni mi&scaron;ići već do 8 sati post mortem prevedeni u stanje podesno za salamurenje, čime je dobijena sirovina potrebnih svojstava za izradu kuvane &scaron;unke.<br />Od ovako proizvedenog mesa (M. semimembranosus), nezavisno od postupka salamurenja (sa ili bez vakuuma), može se proizvesti kuvana &scaron;unka vrhunskog kvaliteta, &scaron;to potvrđuju rezultati ispitivanja kvaliteta kuvanih &scaron;unki proizvedenih od ove sirovine, pri čemu treba istaći da su utvrđene izvesne razlike kod pojedinih faktora kvaliteta kuvanih &scaron;unki prvenstveno rezultat faktora proizvodnje (na primer, operacije salamurenja), odnosno jo&scaron; uvek nestandardnog postupka proizvodnje ovih proizvoda (na primer, neujednačeno ubrizgavanje salamure). Dodatnim izmenama u tehnologiji salamurenja proizvedena je kvalitetna konzerva od mesa u komadima od ostataka mesa buta, uključujući i izdvojeno meso slabijeg kvaliteta (M. semimembranosus), i na taj način je samo jo&scaron; dodatno potvrđeno da je moguće značajno racionalizovati proizvodnju kuvane &scaron;unke uz valorizaciju celokupne muskulature buta.</p> / <p>The aim of the work was to determine the effect of rapid chilling of carcasses (at -31&deg;C up to cca.<br />4 hours, and at 2 to 4&deg;C til 8 i.e. 24 hours post mortem), time of deboning post mortem (8 and 24<br />hours post mortem), after rapid chilling, and way of curing (with and without vacuum) of processed<br />pork (M. semimembranosus) on quality and safety of cooked ham i.e. a task was set to develop a new<br />process of cooked ham production based on significant rationalization of the technological procedure,<br />enabling a certain economic profit, and achieving first class product quality.<br />The effect of rapid chilling of carcasses and time of deboning post mortem, after rapid chilling, on<br />technological, nutritive and sensory quality and safety of pork (M. semimembranosus) intended for the<br />production of cooked ham was investigated. The analysis of obtained results showed that deboning of<br />carcasses is possible up to 8 hours post mortem due to rapid chilling, achieving internal temperatures<br />lower than 7&deg;C, with significantly lower working co sts, weight loss and share of pale meat (M.<br />semimembranosus), i.e. the conclusion is that rapid chilled muscles 8 hours post mortem were in state<br />convenient for curing, obtaining the raw material of required characteristics for cooked ham<br />production.<br />First class quality cooked ham can be produced from pork (M. semimembranosus) obtained in<br />this way, irrespective of curing process (with or without vacuum), as supported by the results of quality<br />investigation of the obtained final product. Some differences found between certain quality factors of<br />cooked ham are the result of processing factors (curing processes, for example), i.e. of still nonstandard<br />production way of this product (for example, uneven injecting of brine). Certain changes of<br />curing technology enabled the production of quality cooked ham from rest ham meat and the<br />separated lower quality meat (M. semimembranosus). These results additionally confirm the possibility<br />of significant rationalization of cooked ham production i.e. possible valorization of the whole amount of<br />ham meat.</p>

<p>Kvalitetno me&scaron;anje pra&scaron;kastih materijala, čestica ili granula je od izuzetnog inženjerskog, energetskog, ekonomskog i ekolo&scaron;kog značaja u raznim granama industrije: prehrambenoj, procesnoj, hemijskoj, farmaceutskoj industriji. Efikasnost me&scaron;anja, dizajn opreme i parametri procesa me&scaron;anja imaju značajan uticaj na kvalitet i cenu poluproizvoda ili finalnog proizvoda.<br />U ovoj tezi, prikazana je upotreba metode diskretnih elemenata (DEM) na modelovanje me&scaron;anja granula i/ili pra&scaron;kastih materijala (granulisani zeolit ili kukuruzna prekrupa) u različitim konfiguracijama statičkih me&scaron;ača Komax i Ross, kao i za modifikovane pužne transportere / predme&scaron;alice. Primenjen je i metod računske dinamike fluida (CFD) za modelovanje protoka fluida u Ojlerovom vi&scaron;efaznom modelu, za predviđanje pona&scaron;anja čestica unutar različitih konfiguracija statičkih me&scaron;alica.<br />Ispitivano je petnaest horizontalnih pužnih transportera sa nepromenljivog koraka, sa modifikovanom geometrijom, različitih dužina pužnice, sa dodatnim elementima na pužnoj spirali, radi istraživanja mogućnosti me&scaron;anja granulisanog materijala, tokom transporta materijala (granulisani zeolit).<br />Rezultati matematičkog modeliranja i numeričke simulacije su upoređeni sa odgovarajućim eksperimentalnim rezultatima na osnovu stepena pome&scaron;anosti me&scaron;avine, primenom kriterijuma relativne standardne devijacije (RSD). Zahvaljujući ovde postavljenim modelima moguće je uraditi optimizaciju geometrije i parametara sistema me&scaron;anja uzimajući u obzir kvalitet procesa me&scaron;anja i cenu finalnog proizvoda.</p> / <p>The quality mixing of powders, particles and/or granules obtain an engineering, energetic, economic and ecological importance of various technologies, food industry, pharmaceutical and chemical industry. The mixing efficiency, the design of equipment and mixing parameters exert a strong impact on quality and the price of intermediate or final product. In this thesis, the use of Discrete Element Method (DEM) is shown for modeling of granular and/or powder flow in various multiple Komax and Ross mixing applications, as well as for the modified screw conveyors premixers . Computational Fluid Dynamic (CFD) method was used for modeling of fluid flow through Eulerian multiphase model, for the prediction of particle displacement within the various static mixers configurations. Fifteen horizontal screw conveyors with invariant pitch, with modified geometry and different screw length , with some additional elements welded on the helix were tested for the possibility of granular material mixing during the material transport (granulated zeolite).<br />The results of the numerical simulation are compared with appropriate experimental results, according to relative standard deviation criterion (RSD). Application of this model provide the optimization of the geometry and parameters of mixing systems taking into account the quality of the mixing process and the cost of the final product.</p>

<p>U doktorskoj disertaciji rešavaju se sledeći problemi: problem opisivanja sistema masovnog opsluživanja kada teorija masovnog opsluživanja nailazi na ograničenja primene, problem predviđanja vremena čekanja, problem modelovanja odnosa na tržištu ekspres usluga kao izvora uticaja na redove čekanja, problem upravljanja brojem aktivnih kanala sistema masovnog opsluživanja i problem uticaja na subjektivno vreme čekanja. Primenom elemenata veštačke inteligencije i statističkih metoda razvijen je model za predviđanje parametra vremena čekanja u realnom vremenu pri jedinicama poštanske mreže za pružanje usluga korisnicima.</p> / <p>The dissertation provides answers to the following issues: the problem of describing the queueing system when the queueing theory encounters limitations in its use, predicting the waiting time, the problem of modeling relations in the market of express services as a source of influence on the queues, managing the number of active channels in the queueing systems and the impact on subjective waiting time. Through application of artificial intelligence and statistical methods, a model has been developed which in real time predicts the parameters of waiting time at the units of postal network that provide service to customers.</p>

<p>Izmenama u konstrukciji vertikalne me&scaron;alice zamenom originalne obloge pužnice sa oblogama koje su imale 13,5%, 27% i 40% perforacija je pobolj&scaron;an proces me&scaron;anja. Ova pobolj&scaron;anja se ogledaju u skraćenju vremena me&scaron;anja 15%, 30% i 50% u odnosu na originalnu konstrukciju, smanjenju utro&scaron;ka rada i energije i otvaranja mogućnosti vraćanja ove vrste me&scaron;alica u masovniju upotrebu, jer su tro&scaron;kovi kupovine i održavanja ove vrste me&scaron;alica daleko niži u odnosu na druge. Izrađen je model sistem za cilindričnu me&scaron;alicu, na bazi primene teorije Markovljevog niza, kao pogodan način za predviđanje procesa me&scaron;anja u ovoj vrsti me&scaron;alica, čak i u industrijskim uslovima. Dobijeni rezultati<br />su pokazali slaganje sa eksperimentalno dobijenim rezultatima, pri čemu je utvrđeno vreme neophodno za postizanje homogenosti u cilindričnoj me&scaron;alici iznosilo 5 minuta za odnos me&scaron;anja 1:10.000, dok za odnos me&scaron;anja 1:100.000 i vreme od 5 minuta, homogenost nije postignuta Poređenjem rezultata programa za analizu slike, koji je prethodno razvijen u okviru metode Microtracer-a, sa ručno dobijenim rezultatima, utvrđen je visok stepen korelacije (R=0.995, 0.979 i 0.987) i ovaj program je ocenjen kao značajno pobolj&scaron;anje i skraćenje vremena potrebnog za dobijanje rezultata.</p> / <p>Changes in the construction of vertical mixers by replacement of the original screw barrel with barrel which had 13.5%, 27% and 40% perforation generally have improved process of mixing. These improvements are reflected in shortening the mixing time of 15%, 30% and 50% comparing to the original construction, reduction of labor and energy and create the possibility of returning these types of mixers in the more common, as the cost of purchasing and maintaining these types of mixers is far lower compared to others. A model system for the cylindrical mixer, based on the theory of Markov chain, as a convenient way to predict the mixing process in this type of mixer, even in industrial conditions. The results show agreement with experimental results, with a determined time necessary to achieve homogeneity in a cylindrical mixer was 5 minutes for mixing ratio 1:10,000, and more than 5 minutes for the mixing ratio 1:100,000. Comparing the results of program for image analysis, which was previously developed under a Microtracers methods with manually obtained results revealed a high degree of correlation (R = 0995, 0979 and 0987) and this program was rated as significantly improving and shortening the time needed to obtain results</p>

<p>Osnovna svojstva telefonske mreţe, koja opisuju njen kvalitet, su kvalitet prenetog govornog signala i kvalitet u uspostavljanju telefonske veze. Na kvalitet uspostavljanja veze utiĉu mogućnost i brzina uspostavljanja veze. Brzina uspostavljanja veze se izraţava vremenima za koje se obave odreĊene aktivnosti u pojedinim fazama uspo-stavljanja veze. Trajanje ovih faza je propisano normama, koje su odreĊene meĊunarodnim propisima i date su u publikovanim preporukama. Osnovni ĉinilac brzine uspo-stavljanja veze je vreme odziva pozvane strane. Ovaj parametar se defini&scaron;e kao vremenski interval od slanja poslednjeg adresnog parametra traţenog korisnika od strane pozivajućeg korisnika, do poĉetka odgovora mreţe. U disertaciji je izvr&scaron;ena analiza vremena odziva pozvane strane u telefonskim mreţama i njegovih svojstava. Usled razlika u preno&scaron;enju adresnih informacija u klasiĉnim i savremenim paketskim mreţama, uslovi koji se odnose na vreme odgovora pozvane strane nisu isti. Ovaj zakljuĉak je formulisan u predlogu za izmenu postojećih normi koje se odnose na savremene mreţe. U nastavku je opisana mogućnost kori&scaron;ćenja vremena odziva pozvane strane u me&scaron;ovitoj mreţi kao &scaron;to je elektroprivredna telefonska mreţa, u cilju dono&scaron;enja zakljuĉka o radu mreţe. U takvoj me&scaron;ovitoj mreţi, razliĉite signalizacije i razliĉito trajanje vremena odziva pozvane strane mogu se iskoristiti za nadgledanje ispravnosti pojedinih delova mreţe odnosno detekciju neispravnih veza u njoj. Koristeći ovu osobinu, predloţen je detektor predalarmnog stanja tj. neispravnih veza u me&scaron;ovitoj telefonskoj mreţi Elektroprivrede Srbije.</p> / <p>Main features of telephone network which describe its service quality are the quality of speech signal and the quality of connection setup. The quality of connection setup is affected by the ability and the speed of connection setup. The speed of connection setup is expressed by the time needed for executing of some connection setup phases. Duration of these phases is prescribed by recommended target values, determined in international recommendations. The key indicator of connection set-up speed is post selection delay. This parameter is defined as the time interval from the moment when the complete address information about the called subscriber is sent from the calling subscriber to the network, till the moment when the answer is received from the network. The analysis of post selection delay in telephone networks and its characteristics is performed in the dissertation. Due to differences in transmission of adress information in classic and modern telephone networks, conditions dealing with the post selection delay are not same. This conclusion is formulated in the proposition for changing existing target values related to modern packet networks. In addition, the possibility of using post selection delay in mixed network, such as the telephone network of electric power utility, for monitoring the network operation is described. In such mixed network, different signaling systems i.e. different durations of post selection delay can be used for checking of proper operation of the network parts and detection of faulty connections. Applying this feature, the pre-alarm state detector is proposed.</p>

<p>Ciljevi: Cilj ove studije je da ispita bezbednost rane karotidne endarterektomije (CEA) u odnosu na odložene CEA nakon akutnog ishemijskog neurolo&scaron;kog deficita (TIA/CVI). Drugi cilj je da istražimo da li postoji razlika u brzini neurolo&scaron;kog oporavka između navedenih grupa. Metode: Ukupno 157 ispitanika u prospektivnoj studiji je praćeno 30 dana postoperativno. Grupa I ili rana CEA, je imala 50 ispitanika operisanih od 3. do 14. dana po TIA/CVI događaju. Grupa II ili odložena CEA, je imala 107 ispitanika operisanih od 15. do 180. dana nakon TIA/CVI. Praćen je proceduralni op&scaron;ti i specifični morbiditet i mortalitet u 30-dnevnom postoperativnom periodu. Rankin skor (mRS) smo koristili za procenu neurolo&scaron;kog invaliditeta. U odnosu na vrednost mRS skora smo formirali dve podgrupe mRS&lt;3 i mRS3. U statističkoj analizi koristili smo Pirsonov hi test, Studentov test, ANOVU analizu varijanse, Boniferonijev test i multiplu analizu varijanse za ponovljena merenja (GLM- general line model), kao i parametarsku i neparametarsku korelaciju i regresiju. Nivo značajnosti je bio 0,05. Rezultati: Prosečna starost ispitanika je bila 66,72 godine uz 66,2% osoba mu&scaron;kog pola. U grupi I je prosečno vreme do intervencije bilo 9,5 dana, a u grupi II 72,22 dana. Grupe su homogene u odnosu na faktore rizika i komorbiditet. Grupa I je imala 54% nestabilnih aterosklerotskih plakova u poređenju sa grupom II gde ih je bilo 31,8% (&chi;2 = 7.084; p &lt; 0.01). U grupi I TIA je imalo 50% ispitanika, a u grupi II CVI nalaza je bilo 68,2% (&chi;2 =4.825; p &lt;0.05). CVI do 1 cm veličine je statistički značajno vi&scaron;e zastupljen u grupi I , a CVI do 2 cm u grupi II (&chi;2 = 6.913; p &lt;0.05). Stopa CVI je u grupi I bila 2.0% a u grupi II je 2.8% (F = 0.083; p &gt; 0.05). Stopa postoperativnog infarkta miokarda (IM) je u grupi I je 2.0% a u grupi II je 1.9%. Stopa specifičnog hirur&scaron;kog morbiditeta je u grupi I 4.0% a u grupi II 3.7%. U grupi I ukupni morbiditet bio 6.0% a u grupi II 7.5%, razlika nije bila statistički značajna (F =0.921; p &gt; 0.05). Mortaliteta u obe grupe nije bilo. CVI/IM/smrt stopa je u grupi I bio 4.0% a u grupi II je bio 4.7% (F = 0.122; p &gt;0.05). Hiperlipidemija je signifikantan faktor rizika za CVI/IM/smrt (&chi;2 = 4.083; p &lt; 0.05). Pobolj&scaron;anje mRS je u grupi I imalo 52%, a u grupi II 31,8% pacijenata (&chi;2 = 5.903; p &lt;0.01). Relativni rizik je 2,4 odnosno toliko puta je veća &scaron;ansa da kod bolesnika dođe do promene mRS ako je bolesnik u grupi I. Pad mRS koji nastupa između trećeg i desetog dana nakon CEA je statistički visoko značajno izraženiji u grupi ranih CEA ( F 3,701 df 1 p=0,029). Kod bolesnika sa TIA u preko 60% slučajeva do&scaron;lo je do pada mRS, a kod onih koji su imali CVI u oko 25.5% (&chi;2 = 18.050; p &lt; 0.01). Kod Rankin skora podgrupe mRS&lt;3 i mRS3 je pad bio značajan i po vremenu (F 18,774; df 6; p=0,000) i po podgrupi ali je daleko brži pad zapažen u podgrupi mRS&lt;3(F 6,010; df 1; p=0,003). Zaključak: Rana CEA je jednako bezbedna kao i odložena CEA u pogledu incidence perioperativnog morbiditeta i mortaliteta. Ranom CEA se postiže znatno brži neurolo&scaron;ki oporavak pacijenata, naročito onih sa TIA i mRS&lt;3 skorom.</p> / <p>Objectives: The aim of this study was to investigate the safety of early carotid endarterectomy (CEA) in relation to the delayed CEA after acute ischemic neurological events (TIA / CVI). The second objective was to investigate whether there is a difference in speed of neurological recovery between these groups. Methods: A total of 157 patients in the prospective study followed 30 days postoperatively. Group I or early CEA, had 50 patients operated from 3 to 14 days after TIA / CVI event. Group II or delayed CEA, had 107 patients operated from 15 to 180 days after the TIA / CVI. Accompanied by the general and specific procedural morbidity and mortality in 30-day postoperative folow up. Rankin score (mRS) were used for evaluation of neurologic disability. In relation to the value of mRS score we formed two subgroups mRS &lt;3 i mRS3. In the statistical analysis we used the Pearson chi test, Student&#39;s test, ANOVA analysis of variance, Boniferony test and multiple analysis of variance for repeated measures (GLM- general line model), as well parametric and nonparametric correlation and regression. The significance level was 0.05. Results: The mean age was 66.72 years with 66.2% of males. In Group I is the average time to intervention was 9.5 days, and in group II 72.22 days. The groups were homogeneous in relation to risk factors and comorbidities. Group I had 54% of unstable atherosclerotic plaques compared with group II, where it was 31.8% (&chi;2 = 7.084; p &lt;0.01). In the group I TIA had 50% of respondents, while in group II CVI was 68.2% (&chi;2 = 4.825; p &lt;0.05). CVI to 1 cm in size were significantly more frequent in the group I, a CVI to 2 cm in group II (&chi;2 = 6.913; p &lt;0.05). CVI rate in the group I was 2.0%, and in group II was 2.8% (F = 0.083, p&gt; 0.05). Postoperative myocardial infarction (MI) in the group I is 2.0%, and in group II was 1.9%. Specific surgical morbidity rate in the group I and 4.0% in the group II 3.7%. In group I total morbidity was 6.0% in group II 7.5%, the difference was not statistically significant (F = 0.921; p&gt; 0.05). Mortality in both groups was not. CVI/IM/death rate in group I was 4.0% in group II was 4.7% (F = 0.122; p&gt; 0.05). Hyperlipidemia is a significant risk factor for CVI/IM/death (&chi;2 = 4.083; p&lt;0.05). Improving mRS in the group I had 52% and in group II 31.8% of patients (&chi;2 = 5.903; p &lt;0.01). The relative risk was 2.4 times as much and is more likely to occur in patients mRS changes if the patient in group I. Improving mRS that occurs between the third and tenth days after CEA was highly statistically significantly greater in the group of early CEA (F 3,701 df 1 p = 0.029). In patients with TIA in 60% of cases there was a decline mRS, and those had CVI in about 25.5% (&chi;2 = 18.050; p &lt;0.01). In Rankin score subgroups mRS &lt;3 i mRS 3 the decline was significant and time (F 18,774; df 6; p =0.000) and in the subgroup but it is far more rapid decline observed in the subgroup mRS &lt;3 (F 6.010; df 1; p = 0.003). Conclusions: Early CEA is as safe as the delayed CEA in respect incidence of perioperative morbidity and mortality. Early CEA is achieved significantly faster recovery of neurological patients, especially those with TIA and mRS &lt;3 compared with delayed CEA.</p>

<p>Profesionalnim vozačima osnovno zanimanje je upravljanje motornim vozilom. Izvođenje radnih zadatka podrazumeva stalnu napregnutost pažnje vezanu za vidne i zvučne podražaje koji se brzo smenjuju, &scaron;to zahteva da vozač adekvatno i tačno reaguje na promene. Prijem informacija, obrada, dono&scaron;enje odluke i izvr&scaron;avanje motornog odgovora su procesi koji prate jedni druge i čine vreme percepcije-reakcije (VPR). Uslovi i zahtevi rada za profesionalne vozače su isti i za mlađe i starije radnike i povezani su sa velikom odgovorno&scaron;ću za ljudske živote i materijalna dobra, bez obzira na to &scaron;to je poznato, da se radna sposobnost menja zbog prirodnog procesa starenja. Merenje i utvrđivanje vrednosti VPR je važan deo ispitivanja u okviru procene zdravstvene sposobnosti za bezbednu vožnju. Ciljevi: Utvrđivanje vrednosti VPR kod profesionalnih vozača i poređenje sa kontrolnom grupom. Ispitivanje uticaja starosti i vozačkog iskustva na VPR kod profesionalnih vozača. Materijal i metode : Ova studija procenjuje deo sposobnosti profesionalnih vozača merenjem VPR prostog i složenog, važnih za sigurnost u vožnji. Istraživanje je sprovedeno u vremenskom periodu od devet meseci i obuhvatilo je 548 ispitanika mu&scaron;kog pola, starosti od 21 do 65 godina. Eksperimentalnu grupu je činilo 278 ispitanika (profesionalni vozači), a kontrolnu 270 ispitanika kojima osnovno zanimanje nije profesionalna vožnja. Testiranje je izvedeno pomoću hardversko-softverskog sistema za određivanje vrednosti VPR na proste i složene audio-vizuelne podražaje. Merenja su sprovedena na tri nivoa težine zadatka: prosto VPR, i testovi složenog VPR na promenu pozicije podražaja i vrste boje. Rezultati: Utvrđene su značajno niže srednje vrednosti VPR na sva tri nivoa testiranja u grupi profesionalnih vozača u poređenju sa kontrolnom grupom. Utvrđena je pozitivna povezanost srednjih vrednosti VPR sa godinama života i dužinom profesionalnog vozačkog radnog staža na svim testovima u grupi profesionalnih vozača. Nisu utvrđene značajne razlike u procentu pogre&scaron;nih odgovora u odnosu na životno doba i dužinu vozačkog staža, &scaron;to govori o pozitivnim efektima profesionalne prakse u vožnji. Nisu utvrđene značajne razlike srednjih vrednosti VPR kod vozača u gradskom ili međugradskom saobraćaju, kao i u odnosu na broj pređenih kilometara mesečno na svim testovima. Obeležja poput starosti (godine života), profesionalne prakse (iskustvo u godinama profesionalne vožnje), neke promene zdravstvenog stanja (postojanje bolesti ili drugih poremećaja) u grupi profesionalnih vozača pokazale su se kao prediktori sa značajnim nivoom povezanosti sa vrednostima VPR. Metodom vi&scaron;estruke regresione analize smo ispitali smo povezanost vrednosti VPR sa posmatranim prediktorima kada ih analiziramo zajedno uzimajući u obzir njihovu međusobnu interakciju. Regresioni model pokazuje kako skup posmatranih obeležja predviđa promene VPR. Zaključak: Utvrđene vrednosti i prediktivni model promena VPR profesionalnih vozača mogu biti korisni podaci u svakodnevnom radu zdravstvenim ustanovama koje procenjuju vozačku sposobnost, kako bi se identifikovali potencijalno rizični vozači sa vi&scaron;im vrednostima VPR, zamorenih i osoba sa početnim o&scaron;tećenjima nervnog sistema, sklonih povredama u saobraćaju i na radu, u cilju prevencije saobraćajnih udesa i povreda, kao i osiguranja da vozači imaju sposobnosti neophodne za bezbednu vožnju. Utvrđene vrednosti VPR mogle bi naći primenu pri oceni radne sposobnosti i kod radnika na drugim zanimanjima gde se očekuje brza i tačna reakcija na određeni podražaj.</p> / <p>The term professional driver refers to people whose main occupation is driving a motor vehicle. Performing work tasks implies a constant strain of attention related to visual and audible stimuli that change quickly, which requires the driver to respond adequately and accurately to changes. Receiving information, processing, making a decision and executing a motor response are processes that accompany each other and make up the perception-reaction time (PRT). The working conditions and requirements for professional drivers are the same for both younger and older workers and are associated with great responsibility for human lives and material goods, regardless of the fact that it is known that working ability changes due to the natural aging process. Measuring and determining the value of PRT is an important part of testing as part of the assessment of health fitness for safe driving. Aims: Determination of PRT values in professional drivers and comparison with the control group. Examination of the effects of aging and driving experience on the PRT of professional drivers. Material and methods: This study assesses part of the ability of professional drivers by measuring simple and complex PRT important for driving safety. The study was conducted over a period of nine months and included 548 male respondents, aged 21 to 65 years. The experimental group consisted of 278 respondents (professional drivers), and the control group consisted of 270 respondents whose main occupation is not professional driving. Testing was performed using a hardware-software system to determine the value of PRT on simple and complex audio-visual stimuli. Measurements were carride out at three levels of task difficulty: simple PRT, and complex PRT tests to change stimuli position and color type. Results: Significantly lower PRT mean values were found at all three levels of testing in the group of professional drivers compared to the control group. A positive correlation was found between the mean PRT values with age and experience of professional driving on all tests in the group of professional drivers. No significant differences were found in the percentage of incorrect answers in relation to the age and driving experience, which shows the positive effects of professional driving practice. No significant differences were found in the mean PRT values on all tests for drivers in urban or interurban traffic and in relation to the number of kilometers per month. Individual characteristics as, aging, professional practice (experience in years of professional driving), changes in health status (existence of diseases or other disorders) in the group of professional drivers showed to be predictors with a significant level of correlation with PRT values. Using the method of multiple regression analysis, we examined the correlation of PRT values with the observed predictors when we analyze them together, taking into account their mutual interaction.The regression model shows how the set of observed features predicts changes in PRT. Conclusion: The determined values and the predictive model of changes PRT of professional drivers can be useful data in the daily work of health institutions that assess driving ability, in order to identify potentially risky drivers with higher PRT values,, tired and people with initial nervous system damage, prone to traffic injuries and at work, in order to prevent traffic accidents and injuries, as well as to ensure that drivers have the skills necessary for safe driving. The determined values of PRT could be used in the assessment of work ability and in workers in other occupations where a quick and accurate response to a particular stimulus is expected.</p>