Kakav beše Muzej Srba u Hrvatskoj ili kako danas o njemu govoriti? Studija slučaja nekritičkog muzeja

Povodom knjige: Andrej Vujnović: "Muzej Srba u Hrvatskoj: studija slučaja", Prosvjeta, Zagreb, 2021

Influence of disturbances in the process of fuel injection on the working processes in the cylinder diesel engine

Neujednačenost radnih procesa u cilindrima dizel-motora se može desiti iz više razloga. Dva najuticajnija faktora na ovu pojavu, a koji se odnose na poremećaje u procesu ubrizgavanja goriva, su: poremećaji u pogledu trenutnog položaja (ugla obrtanja) kolenastog vratila kada započinje ubrizgavanje goriva u nekom od cilindara, tzv. ugao predubrizgavanja, i poremećaji u količini goriva koja se isporučuje pojedinim cilindrima tokom jednog radnog ciklusa, tzv. ciklusna količina goriva. Navedeni poremećaji su daleko izraženiji kod klasičnih, mehaničkih sistema za ubrizgavanje goriva (pumpa visokog pritiska, pumpa-brizgač, itd.), i vrlo često se ne mogu preduprediti pri vanmotorskim ispitivanjima i podešavanjima sistema ubrizgavanja goriva. Simulacija opisanih poremaćaja u realnim uslovima rada dizel-motora, i proširivanje saznanja o njihovom pojedinačnom i zajedničkom uticaju na radne procese u cilindrima, nije nimalo jednostavna. Međutim, danas postoje komercijalni programi koji imaju ugrađene module zasnovane na proverenim jednačinama termodinamike, teorije sagorevanja i teorije strujanja, koje omogućavaju da se ova simulacija izvrši primenom računara. Jedan od takvih programa je program BOOST AVL. Rezultati simulacija dobijeni primenom ovog i sličnih programa mogu biti i pouzdaniji od simulacija u realnim uslovima rada motora, pošto je kod mehaničkih sistema ubrizgavanja goriva, vrlo teško kvantifikovati stepen poremećaja koji se želi simulirati. Dobijeni rezultati mogu biti iskorišćeni za razvijanje metoda identifikacije uticaja opisanih poremećaja na srednji indikatorski pritisak svakog cilindra, pa i celog motora, tačniju procenu mehaničkih gubitaka (stepena mehaničke korisnosti), itd.Unevenness of working processes in diesel engine cylinders can happen for several reasons. The two most influential factors to this phenomenon, which are related to disturbances in the fuel injection process are: disturbances in terms of the current position (rotation angle) of the crankshaft when the fuel injection in one of the cylinders starts, so-called pre-injection angle, and disturbances in the quantity of fuel that is supplied to individual cylinders during one work cycle, the so-called cycle amounts of fuel. These disturbances are more prominent in classical, mechanical fuel injection systems (high-pressure pump, pump-injector, etc.), and very often can not be prevented during the out engine testing and the fuel injection system adjustments. The simulation of disturbances described under real operating conditions of diesel engines, and expanding the knowledge of their individual and joined impact on the working processes in cylinders, is not at all simple. However, today there are commercial software which have built-in modules based on the proven equations of thermodynamics, combustion theory and the theory of flow, which makes it possible to carry out these simulations by using a computer. One such software is AVL BOOST. The simulation results obtained using this and similar software can be more reliable than simulations in real conditions of the engine, because in the mechanical fuel injection system it is very difficult to quantify the degree of the disturbance which is to be simulated. The given results can be used to develop methods of identifying the impact of described disturbances on the mean indicated pressure of each cylinder, as well as the entire engine, a more accurate assessment of mechanical losses (degree of mechanical utility), etc

Practical research of the angle of thermodynamic losses when indicating pressure in the cylinder diesel engine

Vrlo važan literaturni izvor pri proučavanju radnih procesa u cilindrima motora, decenijama unazad, predstavlja članak Güntera Hohenberga 'Definition und Eigenschaften des termodinamischen Verlust-winkels von Kolbenmaschinen', objavljen 1976. godine u časopisu Automobil industrie, izdanje 4. Ovim člankom je teoretski i praktično (eksperimentalno) obrađena tema određivanja ugla termodinamičkih gubitaka na krivoj pritiska bez sagorevanja izmerenoj u cilindru motora. Posebna vrednost Hohenbergovih istraživanja je u eksperimentalnim rezultatima dobijenim osrednjavanjem izmerenih podataka na većem broju različitih motora. Pokazalo se da su ti eksperimentalni rezultati i te kako upotrebljivi za brzo, ali dosta tačno, određivanje ugla termodinamičkih gubitaka na krivoj pritiska bez sagorevanja,kod bilo kog motora. Dijagrami koje je predložio Hohenberg su od koristi i danas, bilo da se primenjuju direktno ili služe za poređenje sa rezultatima neke od savremenijih računskih metoda zasnovanih na termodinamičkoj analizi procesa u cilindru motora. Međutim, teoretski prilaz Hohenberga datom problemu kroz jednačine koje je postavio, daje dosta dobru predstavu o najuticajnijim faktorima na veličinu ugla termodinamičkih gubitaka, ali u sebi ima i dosta grešaka i grubih aproksimacija. Dobrim i lošim stranama ovog vrlo važnog literaturnog izvora kroz poređenje sa jednom od savremenih termodinamičkih metoda vezanim za problematiku određivanja ugla termodinamičkih gubitaka, posvećen je ovaj rad.Very important literary source for the study of work processes in the engine cylinders, for decades, has been an article by Günter Hohenberg 'Definition und Eigenschaften des termodinamischen Verlust-winkels von Kolbenmaschinen', published in 1976 in the magazine Automobil Industrie, Edition 4. This article theoretically and practically (experimentally) deals with the topic of determining the angle of thermodynamic losses on the pressure curve without combustion measured in the engine cylinder. The special value of this research is in the experimental results obtained by averaging the measured data on a large number of different engines. It has been shown that these experimental results are useful for a quick, but quite accurate, determining of the angle of thermodynamic losses on the pressure curve without combustion, with any engine. Diagrams proposed by Hohenberg are used today, whether they are applied directly or used for comparison with the results of some of the more modern computational methods based on thermodynamic analysis of the processes in the engine cylinder. However, the theoretical approach by Hohenberg to the given problem through the equations he set, gives a pretty good idea of the most influential factors on the size of the angle of thermodynamic losses, but it has a lot of mistakes and rough approximations. This work is dedicated to the good and bad sides of this very important literature source through a comparison with one of the modern thermodynamic methods related to the issue of determining the angle of thermodynamic losses

Practical research of the angle of thermodynamic losses when indicating pressure in the cylinder diesel engine

Vrlo važan literaturni izvor pri proučavanju radnih procesa u cilindrima motora, decenijama unazad, predstavlja članak Güntera Hohenberga 'Definition und Eigenschaften des termodinamischen Verlust-winkels von Kolbenmaschinen', objavljen 1976. godine u časopisu Automobil industrie, izdanje 4. Ovim člankom je teoretski i praktično (eksperimentalno) obrađena tema određivanja ugla termodinamičkih gubitaka na krivoj pritiska bez sagorevanja izmerenoj u cilindru motora. Posebna vrednost Hohenbergovih istraživanja je u eksperimentalnim rezultatima dobijenim osrednjavanjem izmerenih podataka na većem broju različitih motora. Pokazalo se da su ti eksperimentalni rezultati i te kako upotrebljivi za brzo, ali dosta tačno, određivanje ugla termodinamičkih gubitaka na krivoj pritiska bez sagorevanja,kod bilo kog motora. Dijagrami koje je predložio Hohenberg su od koristi i danas, bilo da se primenjuju direktno ili služe za poređenje sa rezultatima neke od savremenijih računskih metoda zasnovanih na termodinamičkoj analizi procesa u cilindru motora. Međutim, teoretski prilaz Hohenberga datom problemu kroz jednačine koje je postavio, daje dosta dobru predstavu o najuticajnijim faktorima na veličinu ugla termodinamičkih gubitaka, ali u sebi ima i dosta grešaka i grubih aproksimacija. Dobrim i lošim stranama ovog vrlo važnog literaturnog izvora kroz poređenje sa jednom od savremenih termodinamičkih metoda vezanim za problematiku određivanja ugla termodinamičkih gubitaka, posvećen je ovaj rad.Very important literary source for the study of work processes in the engine cylinders, for decades, has been an article by Günter Hohenberg 'Definition und Eigenschaften des termodinamischen Verlust-winkels von Kolbenmaschinen', published in 1976 in the magazine Automobil Industrie, Edition 4. This article theoretically and practically (experimentally) deals with the topic of determining the angle of thermodynamic losses on the pressure curve without combustion measured in the engine cylinder. The special value of this research is in the experimental results obtained by averaging the measured data on a large number of different engines. It has been shown that these experimental results are useful for a quick, but quite accurate, determining of the angle of thermodynamic losses on the pressure curve without combustion, with any engine. Diagrams proposed by Hohenberg are used today, whether they are applied directly or used for comparison with the results of some of the more modern computational methods based on thermodynamic analysis of the processes in the engine cylinder. However, the theoretical approach by Hohenberg to the given problem through the equations he set, gives a pretty good idea of the most influential factors on the size of the angle of thermodynamic losses, but it has a lot of mistakes and rough approximations. This work is dedicated to the good and bad sides of this very important literature source through a comparison with one of the modern thermodynamic methods related to the issue of determining the angle of thermodynamic losses

The importance and role of hiking for tourist valorization of nature and cultural heritage of Montenegro

Mountaineering and tourism are mutually dependent and compatible activities. Mountaineering has a multiplier role in the development of tourism in a particular destination, whether it's about specific forms of tourism or the addition of a classic tourist offer. Mountaineering is organized sports activity and is an integral part of physical culture. It consists of a whole set of different sports disciplines from recreational, through competitions to extreme. Mountaineering activities are mostly related to trips outside the permanent place of residence and movement in nature, so these trips can be considered special forms of tourism. Beside sporting, aesthetic and health motives, hikers are encouraged by cultural, historical, anthropological and other motives. Mountaineering organizations take care of the construction and maintenance of hiking infrastructure, which is also a touristic one. Mountaineering organizations provide hiking guides and rescuers without which it is impossible to develop a quality offer of mountain tourism. This work discusses the contribution of hiking to the tourist valorization of the natural and cultural heritage of Montenegro

The crankshaft speed as engine diagnostic and control parameter

U radu su prikazane neke mogućnosti primene preciznog merenja trenutne ugaone brzine kolenastog vratila u dijagnostici i kontroli rada motora. Stanje tehnike omogućava precizno, bezkontaktno merenje ugaone brzine kolenastog vratila bez potrebe većih izmena na motoru. Šta više, savremeni sistemi upravljanja radom motora, obavezno uključuju korišćenje relativno jeftinih inkrementalnih davača položaja kolenastog vratila. Informacije dobijene na taj način mogu se koristiti za određivanje trenutnog momenta motora kao i za detektovanje izostanka paljenja ili neregularnog rada pojedinih cilindara. Na ovakav način određen trenutni moment, uz primenu odgovarajućih matematičkih modela omogućava izračunavanje trenutnog pritiska u cilindru motora, što je od izuzetne važnosti za kontrolu i dalje poboljšanje rada motora. Dijagnostika izostanka paljenja pojedinih cilindara je od ključnog značaja za zadovoljenje standarda OBDII koji je na snazi od 1996. god u SAD, a u Evropi primena sličnog standarda obavezna je od 2000. godine.This paper presents some applications of a precise crankshaft speed measurement for engine diagnostics and control. The state of the art of measuring technique enables precise, no contacting measurement of crankshaft speed without necessity for serious engine modifications. Even more, modern engine management systems necessarily incorporate relatively inexpensive incremental crankshaft position sensor. Information, obtained by instantaneous crankshaft speed measurement could be use for an engine torque estimation as well as for an engine torque estimation as well as for an engine misfire or malfunction detection. It is possible to determine cylinder pressure by utilizing engine torque waveform, what is essential for engine control and optimization. Engine misfire detection is extremely important to fulfill the requirements of the OBDII regulation, which is obligated from 1996. in USA and similar regulation is also regulation is also obligated in Europe from 2000

The cultural and chronological context of sites of Bubanj and Velika Humska Čuka near Niš (Southeastern Serbia) and their significance for understanding the emergence and development of the Central Balkans Eneolithic

The research is based on the methods of comparative analyses and synthesis, as well as the interpretation of the existing and fresh data acquired through archaeological excavations at the sites of Bubanj and Velika Humska Čuka near Niš. The following factors have been taken under consideration: geographic setting, resources, mutual spatial relations, stratigraphic characteristics, chronology, character of settlements during the Eneolithic, and other relevant data. The presented cultural and chronological contexts of the two researched sites, as well as other contemporary sites, compared to the pattern of the preceding Vinča settlements, indicated the character of changes that have occurred during the mid-5th millennium BC. The results of the research contribute to the perception of transformation processes within the Late Neolithic communities and the process of eneolithisation in the territory of the Central Balkans.Bulletin of Moscow Region State University. Series: History and Political Sciences no. 5, Circumpontica, iss. III

The crankshaft speed as engine diagnostic and control parameter

U radu su prikazane neke mogućnosti primene preciznog merenja trenutne ugaone brzine kolenastog vratila u dijagnostici i kontroli rada motora. Stanje tehnike omogućava precizno, bezkontaktno merenje ugaone brzine kolenastog vratila bez potrebe većih izmena na motoru. Šta više, savremeni sistemi upravljanja radom motora, obavezno uključuju korišćenje relativno jeftinih inkrementalnih davača položaja kolenastog vratila. Informacije dobijene na taj način mogu se koristiti za određivanje trenutnog momenta motora kao i za detektovanje izostanka paljenja ili neregularnog rada pojedinih cilindara. Na ovakav način određen trenutni moment, uz primenu odgovarajućih matematičkih modela omogućava izračunavanje trenutnog pritiska u cilindru motora, što je od izuzetne važnosti za kontrolu i dalje poboljšanje rada motora. Dijagnostika izostanka paljenja pojedinih cilindara je od ključnog značaja za zadovoljenje standarda OBDII koji je na snazi od 1996. god u SAD, a u Evropi primena sličnog standarda obavezna je od 2000. godine.This paper presents some applications of a precise crankshaft speed measurement for engine diagnostics and control. The state of the art of measuring technique enables precise, no contacting measurement of crankshaft speed without necessity for serious engine modifications. Even more, modern engine management systems necessarily incorporate relatively inexpensive incremental crankshaft position sensor. Information, obtained by instantaneous crankshaft speed measurement could be use for an engine torque estimation as well as for an engine torque estimation as well as for an engine misfire or malfunction detection. It is possible to determine cylinder pressure by utilizing engine torque waveform, what is essential for engine control and optimization. Engine misfire detection is extremely important to fulfill the requirements of the OBDII regulation, which is obligated from 1996. in USA and similar regulation is also regulation is also obligated in Europe from 2000