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Many chronic diseases manifest themselves in prolonged inflammation and often ignored dysregulated lipid metabolism, both also associated with inhalation of certain nanomaterials. Limited knowledge of involved molecular events and their causal connections prevents reliable prediction of outcomes by efficient testing strategies. To unravel how acute nanomaterial exposure leads to chronic conditions, we employed advanced microscopy and omics in vitro , in vivo and in silico . For selected metal-oxide nanomaterials, we show that epithelial cells survive the exposure by excreting internalized nanomaterials and passivating them on the surface, employing elevated lipid synthesis. Macrophages, on the contrary, attack the defending epithelium but die degrading passivized complexes, releasing nanomaterial, which is reuptaken by epithelial cells. Constant proinflammatory signalling recruits new phagocytes that feed the vicious cycle of events resulting in a long-lasting response to a single exposure. The discovered mechanism predicts the nanomaterial-associated in vivo chronic outcomes based on simple in vitro measurements and potentially enlightens other chronic diseases. Graphical abstract

We are daily exposed to a multitude of health hazardous airborne particulate matter with notable deposition in the fragile alveolar region of our lungs. Hence, there is a great need for identification and prediction of material-associated diseases, currently hindered due to the lack of in-depth understanding of causal relationships, in particular between acute exposures and chronic symptoms. By applying advanced microscopies and omics to in vitro and in vivo systems, together with in silico molecular modelling, we have here determined that the long-lasting response to a single exposure can originate from the interplay between the newly discovered nanomaterial quarantining and nanomaterial cycling between different lung cell types. This new insight finally allows us to predict the spectrum of lung inflammation associated with materials of interest using only in vitro measurements and in silico modelling potentially relating outcomes to material properties for large number of materials thus boosting safe-by-design-based material development. Because of its profound implications for animal-free predictive toxicology, our work paves the way to a more efficient and hazard-free introduction of numerous new advanced materials into our lives.

International audience; On a daily basis, people are exposed to a multitude of health-hazardous airborne particulate matter with notable deposition in the fragile alveolar region of the lungs. Hence, there is a great need for identification and prediction of material-associated diseases, currently hindered due to the lack of in-depth understanding of causal relationships, in particular between acute exposures and chronic symptoms. By applying advanced microscopies and omics to in vitro and in vivo systems, together with in silico molecular modeling, it is determined herein that the long-lasting response to a single exposure can originate from the interplay between the newly discovered nanomaterial quarantining and nanomaterial cycling between different lung cell types. This new insight finally allows prediction of the spectrum of lung inflammation associated with materials of interest using only in vitro measurements and in silico modeling, potentially relating outcomes to material properties for a large number of materials, and thus boosting safe-by-design-based material development. Because of its profound implications for animal-free predictive toxicology, this work paves the way to a more efficient and hazard-free introduction of numerous new advanced materials into our lives.

Prežvekovalci so rastlinojedci, ki so izjemno uspešni v razkroju kompleksnih strukturnih rastlinskih polimerov, ki so za vretenčarje neprebavljivi. V specializiranem želodcu – vampu prežvekovalci vzdržujejo kompleksno mikrobioto, ki s sinergijskim delovanjem proizvaja številne celulolitične in hemicelulolitične encime za razgradnjo težko razgradljivih rastlinskih polimerov. Prežvekovalci mikrobom zagotavljajo okolje, bogato s hranili, dokler jim mikrobi s hlapnimi maščobnimi kislinami, ki so končni produkt fermentacije, zadovoljijo 70 % dnevnih energetskih potreb. Z namenom, da bi bolje razumeli ta sistem, smo proučili prehrano petih prostoživečih prežvekovalcev in taksonomsko sestavo vampne mikrobiote treh udomačenih prežvekovalcev. Z enostavno metodo ugotavljanja razlik v dolžini ITS regij rDNA rastlin smo ugotovili prehranske profile petih prostoživečih prežvekovalcev in ugotovili, da je njihova prehrana v glavnem sestavljena iz štirih rastlin: Larix decidua, Anemone nemorosa, Juniperus alpine in Carex nigra. Sestava prehrane je podobna sestavi, ki so jo ugotovili drugi raziskovalci. Dominanta bakterijska debla so Firmicutes, Proteobacteria, Bacteroidetes in Actinobacteria. Za razliko od ostalih študij smo opazili veliko večjo udeležbo debla Proteobacteria pri dvema skupinama prežvekovalcev. Pri teh živalih je tudi razmerje dominantnih debel nenavadno, saj je deblo Proteobacteria pogosteje zastopano kot debli Firmicutes in Bacteroidetes, ki sta v naši raziskavi po številčnosti na četrtem mestu, na tretjem pa je deblo Actinobacteria. Opazili smo nenavadno visoko zastopanost rodov Bifidobacterium, Mitsuokella in Paenibacillus ter rodov Acheoplasma in Geobacillus, ki nista identificirana v ostalih raziskavah vampne mikrobiote. Sestava arhej je precej podobna sestavi iz prejšnjih raziskav. Dominantne so arheje iz debla Euryarchaeota in rodu Metanobrevibacter, ki predstavlja 22 % vseh arhejskih sekvenc in se nahaja v vseh vzorcih. Na koncu potrjujemo, da je sestava vampne mikrobiote v največji meri odvisna od gostitelja in da se med različnimi živalmi razlikuje. Ruminants are herbivores with remarkable ability to degrade complex structural plant polymers otherwise indigestible for invertebrates. In specialized stomach-rumen, ruminants harbor complex microbiota which produces various cellulolytic and hemicellulolytic enzymes through synergistic interactions in order to degrade plant polymers. Ruminants provide the environment rich in nutrients to microorganisms who in turn produce short-chain volatile fatty acids as fermentation end product that provide 70 % percent of the daily metabolizable energy for host animal. In order to better understand this system, we studied the diet of five free-living ruminants and taxonomic composition of the rumen microbiota of three groups of domesticated ruminants. With a simple method of determining differences in the size of the rDNA ITS regions of plants we determined the diet profiles of five animals and found that their diet mainly consists of four plants: Carex nigra, Anemone nemorosa, Juniperus alpine and Larix decidua. Diet composition is comparable to that found by other researchers. Dominant bacterial phyla are Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria. Unlike other studies, we observed a much greater abundance of the Proteobacteria phyllum in two animal groups. Furthermore, the ratio of dominant phyla in those two groups is uncommon because Proteobacteria are generally more abundant than Firmicutes and Bacteroidetes. The latter are in the fourth place and Actinobacteria in third. We observed a surprisingly high abundance of the genera Bifidobacterium, Mitsuokella, and Paenibacillus and two genera, Acheoplasma and Geobacillus, which are not described as a part of rumen microbiota in other studies. The dominant archaeal phylum is Euryarchaeota and most abundant genus is Methanobrevibacter found in all samples and accounting for 22 % of all archaeal sequences. Finally, we confirm that the composition of the rumen microbiota largely depends on the host and that it varies between different animals.

The largest part of contemporary lubricants has been obtained by different procedures of fabrication and processing of crude oil, mainly on the paraffin basis. Many contemporary plants for oil production have been designed and built a few years ago. The successful implementation of the existing technology in this field gives opportunities for optimisation of the existing technology and/or change of the existing production process with introduction of the new regime of work. In accordance with the results of laboratory and exploitation investigations in crude oil refineries and production of basic oils the possibility for reduction of the process of production of the basic oils, excluding vacuum distilling plant under alternation of regime of work of hydro-cracking has been examined. Hydro-cracking has been designed for production of fuels with total conversion of charge. Under changed conditions it is necessary to work with the residue, which has the same distilling interval as the distilling interval of the charge, and serves for production of basic oils.

Veliki dio suvremenih maziva proizvodi se poznatim postupcima prerade i dorade nafte pretežno na parafinskoj bazi. Uspješno ovladavanje tehnologijama u ovome području daje mogućnosti optimalizacije postojećih tehnologija i promjenu namjene postrojenja sa osvajanjem novih uvjeta rada. U članku se na osnovu rezultata laboratorijskih i eksploatacionih istraživanja, analizira mogućnost skraćenja toka procesa proizvodnje baznih ulja za završnu doradu. Time bi se u određenoj mjeri smanjila potrošnja energije po jedinici proizvoda.

Za određivanje preostalog vijeka konstrukcije potrebni su podaci o ponašanju istih ili sličnih konstrukcija u dosadašnjim poznatim slučajevima. U koliko nema dovoljan broj podataka na osnovu kojih bi se donio pouzdan zaključak, potrebno je obaviti određena ispitivanja promatrane konstrukcije i promjene karakteristika materijala ugrađenog u tu konstrukciju. Pouzdaniji rezultati ispitivanja dobijaju se praćenjem i ispitivanjem mehaničkih osobina i promjene strukture materijala u toku eksploatacije. U ovom radu su prikazana eksploataciona ispitivanja stanja konstrukcije ugrađene u procesnom postrojenju kemijskog kompleksa. Ispitivanja su obuhvatila praćenje stanja reaktora i drugih konstrukcija visoke klase u toku 10 godina rada. Na osnovu ovih ispitivanja i prikupljenih podataka, kao i na osnovu dosadašnjih iskustava koja su sakupljena u institutima i specijaliziranim radionicama i laboratorijima, donesen je zaključak o daljem radu konstrukcije u trajanju od 12 mjeseci. U ovom periodu konstrukcija će raditi bez zaustavljanja pogona. Zaključak ovoga istraživanja dat će odgovor na pitanje o daljnjem radu konstrukcije u planiranom vremenu i uslovima eksploatacije.

U radu je prikazan matematički model sustava UPROB razvijenog za montažu tenkova, izgradnju termoenergetskih objekata, te obavljanje remonta složenih postrojenja. Za tehnologije planiranja koriste se linijski dijagrami sa direktnim korištenjem ulaznih podataka iz baze podataka poduzeća. Razvijen je model određivanja kritičnog puta, te definirani koraci za najjeftinije skraćivanje trajanja cjelokupnog plana. Izrađuje se nekoliko varijanti plana (prema izabranim funkcijama cilja), te se management odlučuje za važeću varijantu. Nakon izbora plana omogućeno je kreiranje i praćenje radnih naloga za pojedine zadatke na aktivnostima, te proračun gotovosti aktivnosti, troškova i stanja ukupnog plana.

Pseudomonas aeruginosa je oportunistički patogen koji je poznat po svojim sposobnostima preživljavanja u nepovoljnim uvjetima i prisutstvu različitih antibiotika. Vrlo često se nalazi u bolnicama i nerjetko je uzročnik različitih bolničkih infekcija, te kao takav predstavlja problem. Njegov se genom vrlo lako mijenja i prilagođava okolini, pa tako i dugotrajnom izlaganju antibioticima, te vrlo lako dolazi do razvoja otpornosti. Također, pseudomonas je prirođeno otporan na djelovanje niza β-laktamskih antibiotika zbog aktivnosti kromosomske inducibilne ampC β-laktamaze (klasa C po Ambleru) i nekih stečenih β-laktamaza iz klasa A, B i D. Doripenem je noviji karbapenem u kliničkoj upotrebi koji je po spektru djelovanja sličniji imipenemu i meropenemu nego ertapenemu. U dosadašnjim istraživanjima ovaj antibiotik je pokazao izvrsnu antipseudomonalnu aktivnost, te je ovaj rad proveden u svrhu ispitivanja njegovog djelovanja na višestruko otporne kliničke izolate P. aeruginosa. Osjetljivost na doripenem je ispitana metodom E-testa prema uputama proizvođača, a rezultati su interpretirani prema aktualnim EUCAST standardima. Dobiveni rezultati uspoređeni su s rezultatima osjetljivosti sojeva na imipenem i meropenem dobivenih u Kliničkom zavodu za kliničku mikrobiologiju KBC Rijeka. Višestruko otporni izolati pseudomonasa pokazali su se otporni na djelovanje sva tri karbapenema od kojih je najbolje rezultate imao imipenem, nakon njega doripenem, dok je meropenem bio najslabije djelotvoran.

U radu se analizira stanje naprezanja oko pukotina u kaloti cilindrične posude (pritisak 15.5 MPa i temperatura 454°C). Veličina otkrivenih pukotina na unutarnjoj strani kalote određena je pomoću metode Kontrole bez razaranja. Korištena je metoda konačnih elemenata za određivanje zona naprezanja kod najkritičnije pukotine. Takva analiza je izvršena prije i nakon hidrostatske probe. Prikazan je utjecaj hidrostatske probe na širenje postojećih pukotina i lomno ponašanje popravljene pukotine kroz analizu stanja naprezanja. Izvršena je analiza promjene osobina materijala koja služi kao temelj za procjenu integriteta posude i vijeka eksploatacije.

Process plants in the oil refining industry are designed with a useful life of 15 years. Most users of these types of plants try to extend their exploitation time to over 20 years. This can be accomplished through investment maintenance, which includes modifications or changes of design solutions based on rationalization of production, or by modifying roles of particular elements in the overall process. A great number of modern lubricants is produced through different oil refining procedures and by further processing products of the oil refining process, mainly paraffin based. Successful utilization of the oil refining technology aims our activities to production optimization and/or modifying roles of some plant components, while accepting some new techniques of plant operation. This paper will present research results from oil refining plants for hydrocracking and production of the basic oil distillate that includes the VPS plant into the production process. Investment maintenance, with modifying certain design parameters of the hydrocracking process and including the VPS plant, will lead to selective conversion of the entering charge instead of the total conversion. Referring to that point, an analysis was performed and comparison made between the original design defined data and the data obtained through laboratory tests for hydrocracking and production of the basic oil distillate. Based on this analysis, it can be concluded that there are still some possibilities in the production of fractionator for hydrocracking. That leads to a need for checking and calculating the possibility of controlled modification of certain designed process parameters. This would be done through determining the phase makeup of the process flow at the top and bottom of the debutanizator and of the products on the top of the condenser outlet. It is also important to analyze the influence of these modifications on the process furnace operation.

Classical approach in pressure vessel analysis includes the comparison of stresses present in characteristic section and stresses that are characterized by behaviour of the selected material. Yield stress is a material property that is used the most in design. The second approach includes toughness and the possibility of crack appearance throughout the useful life, as well as the change in material properties during exploitation. This knowledge can be easily used in determining vessel thickness, but also helps in the material selecftion process. The analysis of causes for a change in material properties from manufacturing all the way to the removal from exploitation was performed on over fifty vessels in oil processing. A special attention was given to a reactor vessel that operates under heavy operating conditions (operating pressure of 15.5 MPa, operating temperature of over 450 oC, and with a complex catalytic chemical process using hydrogen). The vessel body is made out of low-alloyed steel ASTM A 387 Gr.D, and is reinforced on the inside with a 4-mm thick layer of stainless austenite steel AISI 347. Another problem is present when determining further usage of this vessel, that is, after observing certain changes in chemical and material properties of the vessel body material during exploitation. Based on the analysis of causes for a change in material properties, it is a possible to improve the design of these types of vessels. It is also possible to determine its useful life more accurately.

Tooth side wear is a result of some mechanical, thermal, or chemical surface stress. More complex wear mechanisms are present when there are high temperatures in tribological areas and with the appearance of oxidizing particles and layers. This paper presents some experimental results that were obtained during the tooth side wear testing due to thermal desorption and oxidation. Complex tribological effects develop an incomplete relationship between the wear in sliding and rolling which is present in every gear mesh and especially in those teeth which are in line contact and in those teeth where the sliding direction is normal to the contact line.

High quality vessels are expected to be very safe and have a high reliability during their useful life. It is often the case in practice that devices and machines in the process industry remain in service even after the expiration of their designed life. This is especially present in the high quality vessels which have a high production and installation cost. The main safety check for these vessels is performed according to rules and regulations for hydraulic (pressure) tests. Research on the high quality vessels leads to the conclusion that hydraulic tests are harmful, which was confirmed by a large number of cracks that appear after these hydraulic tests. This fact gives a basis for adjusting these tests according to the length of service. In several cases, this problem appeared toward the end of the useful life of the vessel. Hydraulic tests that are performed during manufacturing (inter-phase check) and during the trial operation did not cause crack appearance. The problem itself is beyond the interest of users and comes back to the designer and planner as well as those who control the application of rules and standards.

Regulations in the field of pressure vessel include inevitable actions in design, production and exploitation of pressure vessels. The problem of safe and reliable work exists in countries known for production of the highest class pressure vessels, as well as in those countries that use those vessels. Long term experience in production and exploitation of pressure vessels of all classes is now used as the basis for defining of rules, regulations and standards. In this article, different regulations for vessels, which are used in classical and nuclear technology of developed countries, are critically examined. Using comparison and critical review of certain parts of those regulations, based on research, need for revision of regulation of parts concerning hydraulic tests in the period of exploitation is obvious. This especially includes those types of appliances whose life has expired, but because of a high price, the length of their usage is extended. The comparison of references, regulations and standards which are usually used for pressure vessels, should be used as a guide for definition of the Book of Regulations for Technical Norms of Vessels.

Proper operation and safety of pressure vessel is achieved by maintaining stresses during exploitation belo the critical values. In other words, not letting operating conditions become critical conditions.

U radu se ukazuje na važnost kvalitete pogonskih voda u industrijskim postrojenjima. Navedene su prednosti i nedostaci korištenja klora ili klor- dioksida kod pripreme napojne vode, sa preporukama vezanim za normativne i zakonske aspekte, koje su prihvaćene u razvijenim evropskim zemljama.

U radu su prikazani rezultati u razvoju digitalnog poduzeća na primjeru poduzeća za proizvodnju opruga ESCO d.o.o. u Hrvatskoj. Koncept razvoja digitalnog poduzeća odvijao se u dva pravca: automatizacija proizvodnih kapaciteta i digitalizacija i integracija pripremnih i proizvodnih procesa u ERP sustavu. Postignuti rezultati u ostvarenoj konkurentnosti na tržištu EU pokazuju opravdanost ulaganja u automatizaciju, informatizaciju i digitalizaciju radnih procesa u poduzeću.

The length of useful life of the reactor vessel is much more questionable than the estimate of a probable breakdown. It particularly arises as a need and an obligation after regular technical inspections. The problem of determining the remaining life of the vessel is especially arises when there are errors or cracks on the vessel walls. Research on high quality vessels leads to the conclusion that hydraulic tests are harmful, which was confirmed by a large number of cracks that appeared after these hydraulic tests. This fact gives a basis for evaluation of these tests and their adjustment depending on the length of exploitation. The analysis of causes for a change in material properties from manufacturing all the way to the removal from exploitation was performed on over fifty vessels in oil processing. Special attention was given to a reactor vessel that operates under heavy operating conditions and with a complex catalytic chemical process using hydrogen. Changes in material characteristics were monitored from the production of the reactor vessel until its shutdown and removal from service. The causes for crack occurrence and expansion in vessel walls and heads were analyzed. The occurrence of new cracks and expansion of old cracks was particularly considered during hydraulic tests.

U radu je dana koncepcija centra za razvoj i primjenu novih proizvodnih i informatičkih tehnologija, poduzetništva i menadžmenta na Strojarskom fakultetu u Slavonskom Brodu. Pokazalo se da su transformacijom velikih proizvodnih sustava (Energoinvest, Rade Končar, Đuro Đaković, Prvomajska, Jugoturbina, Unis, Jelšingrad) na srednja i mala poduzeća, nestali Instituti i Razvojni odjeli, koji su bili generatori razvoja, ne samo u tim proizvodnim sustavima, već i za veliki broj srednjih i malih poduzeća kao i poduzetnika i obrtnika. Na primjeru projekta zajedničkog laboratorija za edukativno digitalno poduzeće strojarskih fakulteta (FESB Split, FSB Zagreb, Tehnički fakultet Rijeka i Strojarski fakultet u Slavonskom Brodu) predlažu se Strojarski fakulteti za nositelje tehnološkog razvoja.

U radu je pregledno obrađen izvod iz šest važnih europskih standarda za označivanje čelika, koji su doneseni u periodu 1991.-2002. Države u tranziciji kao Hrvatska, BiH i dr. moraju stalno pratiti razvoj i stanje i na području standardizacije i osiguranja kvalitete radi što bržeg njihovog uključivanja u europske i svjetske trendove, a to je ujedno i vrlo važno za predstojeće europske integracije.

Konstrukcija mlaznica prskalice za zaštitu bilja rasprskivanjem definiraju tehnički zahtjevi (funkcionalna potrajnost, odnosno ispunjavanje funkcije za koju je predviđena u određenom vijeku trajanja i tehnološka ispravnost, odnosno oblikovanje koje će omogućiti jednostavnu i jeftinu izradbu, kontrolu, transport, skladištenje i montažu) i zahtjevi isplativosti (što manji troškovi od projektiranja i konstruiranja, preko izradbe, eksploatacije i održavanj, do isključenja iz uporabe). Optimiranje navedenih tehničkih i gospodarskih zahtjeva najbolje se ostvaruje prikupljanjem podataka iz realne eksploatacije. U radu je analizirana funkcionalna ispravnost u smislu pokrivenosti površine lica i naličja lista tekućinom pesticida, primjenom različitih konstrukcija mlaznica pri promjeni radnog tlaka rasprskivanja. Ispitivanja su obavljena upotrebom T-mlaznica ili mlaznica s prorezom koje oblikuju lepezast mlaz.

The article shows the review of two models for determination of optimal intervals of preventive maintenance. The data that have been used in suggested models is taken from Management Information Maintenance System – MIMS and its following subsystems: Technical data, Corrective and Preventive Maintenance. Models are given in mathematical forms and its implementation in Management Information Maintenance System, as well.

This paper explains application of CNC automat for TIG welding of butt pipe joints in steam boiler manufacturing. Welding is performed in single pass "I" weld groove preparation. Because of the small diameter pipe weld specifics, welding parameters were split in several different parts, related to pipe circumference. Beside the welding parameters for automatic TIG welding of 15Mo3 and 10 CrMo 9 10 pipes, authors offer some results of weld joints quality investigation. In the end of the paper, the techno-economic comparison between automatic and manual TIG is given

Brzi ekonomski i tehnološki razvoj doveli su do velikih promjena u živote pojedinca, društva i države. Nova mjerila konkurentnosti proizvoda i usluga (znanje, inventivnost) omogućile su i manjim, prirodnim bogatstvima siromašnijim zemljama, da postanu značajniji sudionici globalizacije. Istovremeno se povećavaju razlike između razvijenih i zemalja koje su posljednje desetljeće imala usporen razvoj, prijeteći da zbog sporog napredovanja te razlike postanu još veće. U radu su prikazani trendovi primjene novih tehnologija u razvijenim zemljama te njihov utjecaj na povećanje proizvodnosti i poboljšanje konkurentnosti proizvodnih sistema.

U strojarskim konstrukcijama poznato je da je jačina adhezivne veze na mjestima neposrednog kontakta dva metala proporcionalna stupnju rastvorljivosti u čvrstom stanju jednog metala u drugom. U slučaju potpune rastvorljivosti (kod metala koji stvaraju legure) mikrozavarena mjesta pružaju velike otpore smicanju pri kretanju i visoke koeficijente trenja.

Znanost o konstruranju kao samostalna znanstvena disciplina novijeg je datuma i dosta teško zauzima svoje mjesto i obim koji joj pripada. Pravilno konstruranje s obzirom na održavanje dio je znanosti o konstruiranju. Iznalaženje optimalnih rjšenja pri konstruiranju odvija se postepenim načinom razrade uzročno posljedičnih veza konstruiranja i čimbenika koji utječu na kvalitetu konstrukcije. dio informacija s kojima se obavlja provjera valjanosti konstrukcije dobiva se praćenjem rada postrojenja u eksloataciji uz optimalne uvjete održavanja. U članku je prikazan primjer izmjene konstruktivnog rješenja podnih ploča reaktorske peći linije prerade nafte na temelju saznanja iz eksloatacije i potreba za lakšim te ekonomičnim i pouzdanim održavanjem.

Design is a relatively new scietific discipline and represents one of the technical disciplines. In studies the process of creating structures with a goal of finding certain design rules so that, based on those rules, methods and techniques can be developed to mater the design process. Proper design based on maintenance, reliability theory principles, and new findings from the area of fracture mechanics are all part of the design science and have only recently been given proper value. Part of information that leads to optimal design solutions is gained through studying elements and assemblies based on reliability theory during all steps of their operation.

Sitting down for long periods of time can lead to health problems. While sitting, the pressure is present at contact surfaces due to the basic principle that the body weight is distributed through bones and soft tissue onto the seat and vice versa. This pressure acts on big muscles and big bones so its continuous influence can cause changes in the soft tissue and in bones. Research was done at several workplaces with five different shapes of seats. Testing sample included 37 male and 33 female participants who work while sitting down. Participants were of different age groups and gender. Their anthropometrical characteristics were measured: height, weight, sitting pressure, hip and chest circumference, and body posture while working. Seat characteristics were also analyzed, including: seat dimensions (width, length), seat shape, seat inclination, seat hardness. The main goal of this research was to determine, out of available seats, which seat is acceptable for the given group of participants based on comfort (pressure magnitude and distribution while sitting). The paper uses an original model for evaluating seating parameters when selecting an acceptable chair. Evaluating model uses the theory of graphs in analyzing evaluation criteria. Defining a weighing factor for each analyzed parameter lead to establishing a hierarchy of chairs. The chair with the highest combined weighing factor represents an acceptable type of chair for the given criteria.

U ovom se radu obrazlaže primjena On-line monitorig sistema za praćenje, prikupljanje i obradu glavnih parametara eleketrolučnog zavarivanja - napona i jačine struje kod automatskog MAG zavarivanja uz primjenu bazičim praškom punjene žice i CO2 zaštitne atmosfere. Prikazana je On-line distribucija srednjih kvadratnih vrednosti parametara zavarivanja, te Off-line distribucija realnih vrijedosti parametara zavarivanja. Pored ostaloga je prikazana i međusobna ovisnost napona i jačine struje zavarivanja za stohastički izabran interval snimanja parametara zavarivanja. Predstavljeni sistem ima mogućnost registriranja do 20 kHz podataka po svakom kanalu.

U članku su prikazana istraživanja uzroka pucanja vijaka na prirubničnom spoju procesnih cjevovoda. Pokazana je povezanost degradacije vijaka i nepravilnog rada višestepenih klipnih kompresora. Mjerenja vibracija na cjevovodu su pokazala da su isti prisutni i na dijelu cjevovoda na kojima dolazi do pucanja vijčanih spojeva. Izvršena su mjerenja karakterističnih vibracijskih veličina na sastavnim elementima kompresora i kompresora sa temeljom. Zaključeno je da na pojavu vibracija presudan uticaj imaju elastični elementi kompresora, kao i oslonci i ovješenja cjevovoda koji su procesno povezani sa kompresorima.

Spherical and cylindrical pressure vessels are manufactured as welded structures, where cracks could be initiated/propagated during fabrication, pre-service hydro-test, service itself, service welding repair, or during the service hydro-test. In this case, fracture mechanics approach is necessary. This paper analyzes the stress state around cracks in the bottom head which is one of the main components in a cylindrical pressure vessel (radius of 1056 mm, wall thickness of 92 mm, pressure of 15.5 MPa and temperature of 454°C). Sizes of several detected cracks at the inner surface are determined by the NDE methods. Finite element analysis is performed to determine the stress zones in the vicinity of the most critical crack. Such analysis is done before and after the hydro-test. It will show the influence of the hydro-test on propagation of the existing cracks and fracture behavior of repaired cracks through the stress state analysis. Changes in material properties were analyzed. Results will be used to assess the pressure vessel integrity and estimate its useful life.

U radu procesnih postrojenja pojavile su se vibracije takvog karaktera da su uzrokovale pucanje vijaka na prirubničnom spoju cijevnih instalacija visokog pritiska. Cijevne instalacije rade pod visokim pritiskom i u sklopu su kompresorske stanice sa četiri višestepena klipna kompresora. Na višestepenim klipnim kompresorima vodika u postrojenju izomeracije zapažene su izrazite vibracije u toku rada. Ove vibracije su se u znatnoj mjeri dalje prenosile na cijevne vodove. Mjerenja vibracija na cjevovodu su pokazala velike vibracije i na većim udaljenostima od kompresorske stanice. U članku su prikazana istraživanja uzroka nastajanja povećanih vibracija. Na osnovu rezultata provedenih mjerenja, njihove analize ali i analize ukupnih utjecaja na konstrukciju postrojenja izomeracije, zaključeno je da najveći utjecaj na pojavu velikih vibracija imaju elastični elemenati za spajanje cilindara različitih stepeni kompresora, elementi ovješenja i oslonaca cjevovoda uz kompresorsku stanicu i na postrojenju i rad nekih procesnih pumpi.