3D-layouts of machine tools for multipurpose machining of rotary components

U radu je predstavljen koncept za izradu različitih 3D-prikaza alatnih strojeva s jednom ili dvije klizne staze za kombiniranu obradu steznih i obradaka tipa od središta do središta, utemeljenih na principu modularnosti. Novi se 3D-prikazi nude za uzastopnu ili istovremenu, jednostranu ili dvostranu obradu steznih i dijelova tipa od središta do središta. U prvom dijelu rada prikazuju se projektne i tehnološke mogućnosti tipičnih predstavnika tako zvanih alatnih strojeva s jednom kliznom stazom kao 3D-prikazi. U drugom se dijelu daju tipični 3D-prikazi alatnih strojeva s dvije klizne staze gdje se za svaku od staza koriste dvije paralelne vodilice. Učinkovito povezivanje grube i završne obrade može se postići jedino novim alatnim strojevima za stezne i obratke tipa od središta do središta, a oni se u ovom radu spominju kao "višestruki" (multipurpose).In the paper is presented a concept for design of different 3D-layouts of one- and two-carriage machine tools for combined machining of chuck and centre to centre type workpieces based on a modular principle. New 3D-layouts are offered for consecutive or simultaneous, one-sided or bilateral machining of chuck and centre-to-centre type components. The first section of the paper presents design features and technological capabilities of typical representatives of the so-called single-carriage machine tools as 3D-layouts. The second section presents typical 3D-layouts of double-carriage machine tools where two parallel guideways are used for guiding each one of the carriages. The effective integration of the rough and finishing machining can be accomplished only by new machine tools for chuck or centre-to-centre type workpieces referred in the present paper as "multipurpose"

Combined Machine Tool for Stepped Shafts

The paper deals with a novel design of a combined machine tool in comparison with known contemporary analogues. It is designed for multifunctional machining of workpieces in one or two setups in collet and centre-to-centre design. Typical of this machine tool is the use of a bed with a trapezoidal cross-section with inclined longitudinal guides on both sides for the slides used for rough, fine and finish machining. With this design, the slides are spatially separated and lightly loaded. The material removal during roughing and finishing is separated from each other. The grinding slide and its guides are not subjected to additional thermal deflections caused by the high-temperature crisps produced during turning, and the slide for roughing and finishing is spatially protected against the influence of grinding powder. The bed meets the requirements for a thermos symmetrical design and allows internal cooling. The advantages of this arrangement from the design, technical and economic points of view are presented

Preparation of video lectures for distance education

U ovom radu je predstavljena primjena softvera Camtasia Studio 8 i neki doprinosi autora pri pripremi video predavanja za obrazovanje na daljinu. Razvijeni su filmovi na nekoliko jezika i dostupni su putem interneta. Redoviti i izvanredni studenti mogu ih studirati u detalje koristeći računalo ili pametni telefon u vrijeme i na mjestu koje im najviše odgovara. Odabrane informacije u video predavanjima se predstavljaju puno brže i točnije u usporedbi s tradicionalnim metodama poučavanja, što štedi vrijeme. Uključene su animacije s komentarima, simulacije i ubačeni su video filmovi koji vizualiziraju prezentirani materijal. Autori surađuju na novom projektu međunarodne suradnje u sklopu CEEPUS programa za pripremu video predavanja i vježbi na njemačkom i engleskom jeziku za studente koji studiraju na partnerskim sveučilištima.In this paper the application of the software product Camtasia Studio 8 and some developments of the authors when preparing video lectures for distance education are presented. The developed films are in several languages and are accessible in the Internet. Regular and part-time students may study them in details using a computer or a smartphone in time and place most convenient for them. The selected information in the video lectures is presented much faster and accurately compared to the traditional methods for teaching, which saves time. There are included animations with comments, simulations and inserted video clips to visualize the presented material. The authors work in collaboration on a new project for international cooperation under CEEPUS program for preparation of video lectures and exercises in German and English for students studying in the partner universities

Combined Machine Tool for Stepped Shafts

The paper deals with a novel design of a combined machine tool in comparison with known contemporary analogues. It is designed for multifunctional machining of workpieces in one or two setups in collet and centre-to-centre design. Typical of this machine tool is the use of a bed with a trapezoidal cross-section with inclined longitudinal guides on both sides for the slides used for rough, fine and finish machining. With this design, the slides are spatially separated and lightly loaded. The material removal during roughing and finishing is separated from each other. The grinding slide and its guides are not subjected to additional thermal deflections caused by the high-temperature crisps produced during turning, and the slide for roughing and finishing is spatially protected against the influence of grinding powder. The bed meets the requirements for a thermos symmetrical design and allows internal cooling. The advantages of this arrangement from the design, technical and economic points of view are presented

First results from the releases of Cinereous Vultures (Aegypius monachus) aiming at re-introducing the species in Bulgaria – the start of the establishment phase 2018–2022

The current work presents the preliminary results of the Cinereous Vulture (Aegypius monachus) releases in the Balkan Mountains in 2018–2022, aiming at the species re-introduction in Bulgaria, where it was listed as locally extinct since 1985. The first imports and releases of Cinereous Vultures in Bulgaria started in 2018. Until mid-2022, 72 individuals were released in the Eastern Balkan Mountains (Kotlenska Planina SPA and Sinite Kamani Nature Park) and Vrachanski Balkan Nature Park. Of them, 63 immatures imported from Spain were released from aviaries and nine juveniles captive-bred in European zoos were released by hacking (fledging from an artificial nest). We compared the success in survival and establishment between the different release sites and methods used to adjust the ongoing technics and tactics and to support knowledge improvement for future similar projects.From the nine Cinereous Vultures released by hacking, the results were as follows: 1.00 fledging success, but only 0.22 survival in the first six months – combined period of acclimation, first migration and the first winter. All survivors from that period reached maturity into the wild, but all emigrated from the release site and settled elsewhere.Of the 63 individuals released by aviaries, 32 individuals were released in the Eastern Balkan Mountains (18 individuals are still alive – 0.56 survival; 14 individuals settled in the area, which accounts for 0.44 of all released birds and 0.78 of the survivors). Thirty-one individuals were released in Vrachanski Balkan Nature Park (23 individuals are still alive – 0.74 survival; 22 individuals settled in the area – 0.71 of all released birds and 0.96 of the survivors). Based only on aviary method comparison, the settling of the individuals in the release area was alike in the two sites. However, the Vrachanski Balkan Nature Park performed better in survival – both in acclimation and establishment periods.While comparing the release methods – hacking and release from the aviary – the following results were observed: the survival rate during acclimation was 0.86. Due to more considerable losses during the first migration and dispersal in the individuals released by hacking, the survival rate of 0.22 was significantly lower compared to 0.73 for the birds released from the aviary. Additionally, in both methods, a similar pattern in the first winter and spring migration dispersal was observed. Although the survival was equal in the released-by-hacking or aviary birds after the first year onwards, it is essential to note that the emigration of the hacked birds from the release site was 1.00. In comparison, the birds released from aviaries largely remained and settled in the release area (> 0.77 of the survivors). The cost of release and related acclimation, settling, dispersal and the first winter was the greatest: 0.12–0.17 per period, or cumulatively, it was about 0.27. Survival increased and stabilised to > 0.90 after the first year in the wild and reached nearly 1.00 after two years in the wild onwards.Two distinct nuclei of the Cinereous Vulture were established along the Balkan Mountains – the Eastern Balkan Mountains with 18–23 individuals and four formed pairs using a territory of about 642.74 km2 – 95% home range and 85.72 km2 – 50% core area with center being the town of Kotel; and Vrachanski Balkan Nature Park with present 23–29 individuals, of which 2–3 pairs formed so far, using a territory of about 1,143.66 km2 – 95% home range and 22.89 km2 – 50% core area with center being the village of Zgorigrad. The species readily accepted breeding in artificial nest platforms built by professional arborists on different tree species – oak, beech, sycamore and pine. The only naturally built nests were on the ground (n = 2) (unsuccessful) and in Scots Pine (n = 1) (successful). In 2021 and 2022, in each of the two sites, the first successful reproductions were recorded, which marked the return of the Cinereous Vulture as breeding species – 28 years after the last occasional record of a single breeding pair in the country and 36 years after it was officially listed as locally extinct in Bulgaria