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A View of The Influence of Constrained Torsion on Behaviour of Thin-Walled Cantilever Channel-Section and Z-Section Beams
No full textA thin-walled cantilever beam with an open channel-section and a Z-section subjected to bending and constrained torsion is studied. The beam mass of structural thin-walled beam elements for given loads, material and geometric characteristics is minimized. The area of the cross-section is assumed to be the objective function. Stress constraints are introduced. The Lagrange multiplier method is applied to the problem. The equations, whose solutions represent the optimal values of the ratios of the parts of the chosen cross-section, are derived. As a result of the calculation the modified constrained functions are derived as polynomials of the fourth and eighth order with the coefficients derived in this paper. Illustrative examples are given. The Finite Element Method is applied to the obtained results for numerical calculations
The effect of build orientations and raster angles on impact toughness of PET-G FDM material
No full textPolyethylene terephthalate glycol (PET-G) material is used in additive manufacturing (AM) for the
production of moderately loaded polyester-based parts. Scientific papers show that build orientation and printing direction angle substantially influence the mechanical properties of additively manufactured specimens. This paper explores the effect of build orientations (flat, on edge and upright) and raster angles (0° and 90°) on the impact toughness. In this study, a low-energy instrumented Charpy Instron Ceast 9050 (Figure 1.) test was used as an experimental method to evaluate the impact behavior of PET-G material. An experimental evaluation of impact toughness in the case of AM impact specimens fabricated with different build orientations and printing angles was performed. The impact tests were carried out on five specimens per batch (a total of 30 specimens). The results obtained from an instrumented pendulum were compared between different specimen groups to gain insight into the influence of build orientations and raster angles on PET-G material impact specimens. It was confirmed that different build orientations and raster angles have a strong influence on the final mechanical properties of this material
Atlas Roman Pot Heat Sink Development for Low Pressure Working Conditions
No full textThe development of a heat sink for Atlas Roman Pots for the purpose of ATLAS Forward Proton (AFP) detector upgrade in 2024, is presented in this paper. During proton collisions, the Roman Pots (RP) used in the Large Hadron Collider (LHC) move very close to the beam. Since beam intensity had been gradually increased over the years, the temperature increase was also observed on the RP wall and bottom. Eventually, it started raising concerns that it would compromise surrounding vacuum conditions. Hence, in order to reduce RP temperature,
a heat sink needed to be developed which would transfer the excessive heat from the RP wall and bottom to the flange, which remains roughly at room temperature even during beam conditions. The RP and the flange are made of stainless steel and due to their low thermal conductivity it is impossible to avoid overheating of the RP bottom. A few concept designs were developed and the temperature field change with time was simulated in ANSYS Fluent. Since the heat sink has no symmetry planes, the simulations was performed in 3D numerical domain. The influence of Roman Pot movement on heat transfer was analysed. Operating conditions are very close to vacuum, so natural convection can be disregarded. Heat transfer mechanisms that were taken into account are radiation and conduction. Experimental investigation of the prototype was done at CERN at atmospheric and low pressure conditions. Furthermore, the temperatures are continuously
being remotely monitored in LHC working conditions. Temperature distribution obtained by numerical simulations showed very good agreement with the experimental results
Mining Management Strategy Towards Circular Economy and Sustainable Development
No full textMining is an important economic branch in Serbia, because it is highly
dependent on coal in the production of electricity. About 70% of electricity in Serbia is
produced in coal-fired thermal power plants. Viewed in the long term from the
perspective of the declared Green Transition until 2035, it is clear that coal exploitation
will decrease in the coming years. However, it cannot happen quickly. It is estimated
that coal will still remain the main source of energy until 2050, in permanent or reserve
operation. In order for this transition to be realized, it is necessary to first provide
appropriate renewable energy sources that enable safety and stability in the production
of electricity, which is not a simple goal. Complex technological processes in mining as
an economic branch facing the big tasks of transition to a green future and a sustainable
economy require a responsible attitude and the application of the modern and innovative
methods of environmental protection. That is why the rehabilitation of the environment
during and after the exploitation of ore deposits is an important and promising research
area. Modern methods of artificial intelligence help to find better solutions for
recultivation, revitalization and arrangement of degraded areas and mining pits faster.
This research will not only look for solutions in the field of compensation and/or
environmental restoration in the mining industry, but will also make a step forward
towards the use of some mining residues and their recycling. The goal is to use them as
raw materials in another economic branch. The motive is environmental protection with
zero waste reduction. The task is to introduce a circular economy. For a linear economy
in which raw materials are only used and waste is deposited, and the environment is
polluted, it has long been understood that it is an unsustainable and outdated approach.
Sustainable development requires that the principles of circular economy be applied in
mining, and artificial intelligence as a modern tool in the function of finding advanced
solutions for environmental restoration and reuse of discarded raw materials helps in achieving those goals. The research presented here improves the economics of the
mineral-raw material complex and upgrades it to the level of sustainable mining
APPLICATION OF NUMERICAL ANALYSIS IN DETERMINATION OF FRACTURE RESISTANCE OF PIPELINE MATERIALS
No full textINTEGRITY OF THE STEAM COLLECTOR MADE OF STEEL 12X1MF
No full textThe method of proving the integrity of the output collector of the steam super heater manufactured from the material 12X1MF, presented in the paper, is a material for working at elevated temperatures that is most often used in facilities of thermal power plants. Proving the integrity of the assembly was performed primarily using non-destructive testing methods, software processing of metallographic samples, conventional methods of proving the stress state in the material, application of the finite element method for the entire assembly and hydrostatic testing of the assembly with cold water pressure. Each collector segment is individually tested for the overall integrity of the super heater outlet collector. In addition to conventional methods of testing with/without destruction, software processing of the microstructure was also used in order to evaluate the proportion of the beanie phase in the structure, which is the main quality feature of the 12X1MF material. The qualification of the welding technology with additional materials available on the European market was an indispensable part of the proof of the integrity of the welded joints as the most critical segments of the assembly. The final stage of the assessment of the integrity of the assembly was the finite element method and hydrostatic testing of the assembly with cold water pressure
DRONE INSPECTION AS AN ADVANCED NDT METHOD IN THE OIL AND GAS INDUSTRY
No full textThe paper presents drone inspection as an advanced non-destructive testing method in the oil and gas industry. This type of monitoring is performed where visual inspections are required as part of maintenance or inspection procedures. By using a drone to collect visual data, we can assess the structural integrity of constructions without placing inspectors in dangerous situations, thus reducing risk and significantly lowering costs. Drone inspections are increasingly used in refineries and on oil platforms. Particularly for offshore inspections, drones save time, improve safety, and reduce mobilization costs. This paper will discuss the application of drone inspections at methanol tanks in a refinery in Norway, which are part of the regular inspection program according to the API 563 standard. The results of both external and internal inspections of the tank will be presented, covering general visual inspection (GVI) and closer visual inspection (CVI). The use of drones in regular API inspections greatly reduces inspection time, increases efficiency, and eliminates the need for scaffolding and rope access personnel. Additionally, high-resolution video inspection data and high-quality captured images can be used for detailed condition assessments
First Escalators and Their Inventors Until the End of the 19th Century
No full textVery important factors in vertical transportation are escalators (moving stairways). In this historical respect the escalators and moving stairways differ from elevators, which basic principles were formulated several centuries ago, but at their beginnings they were considered as some kind of elevators and/or conveyors. Nowadays, escalators are widely used and operate in different places such as shopping centers, underground stations, airports, etc. The basic design employed has not varied from those patented more than a century ago. All crucial patents regarding the fascinating history of escalators have been developed in the second half of the 19th century, until 1900. However, some of those patents are quite different from the traditional ones. Inventors and engineers, who created the first patents and installations of escalators as we know them nowadays, can be considered as fathers” of escalators. They are: Nathan Ames, Leamon Souder, Jesse Reno, George Wheeler, Charles Seeberger, Jacques Hallé and James Dodge. Their patents and installations are described in chronological order, including some available short biographical notes on those first inventors of escalators. The formal name of moving stairways the word “escalator” was trademarked in 1900 by Otis Company and coincides with escalator debut at the Paris Exposition
ЕГЗОСКЕЛЕТ ЗА РУЧНИ АЛАТ
No full textЕгзоскелет за ручни алат, саСТОЈИ се из спољашње цеви (9) кроз КОЈУ Је клизно уметнута унутрашња цев (13), при чему су и кроз спољашњу цев (9) и кроз унутрашњу цев (13) пробушени отвори (9а, 13а) тако да се положај унутрашње цеви (13) у односу на спољашњуцев (9) подешава завртњем (11) за фиксирање међусобног положаја његовим провлачењем кроз отворе (9а, 13а). На крај унутрашње цеви (13), која се усмерава према рамену или надлактици корисника причвршћен је кундак (12), а са друге стране завртњем (6) причвршћен је носач (5) шипки (4). На шипке (4) клизно је навучена шипка (17) савијена у "U" профил, а на њу клиз но навучена шипка (18). На шипку (18) навученаје цев (1) на коју је причвршћен доњи стезач (2) алата, на који је завртањском везом причвршћен горњи стезач (3) алата. Између носача (5) и спољашње цеви (9) постављен је еластични прстен (8), На спољашњу цев (9) навучена је чаура (10) са чичак траком (14), а друга чичак трака (16) причвршћенаје за носач (5). Механизам је универзално применљив за све кориснике без обзира на телесне димензије и масу, а нарочито за раднике који на послу значајно време проводе у коришћењу ручних електричних алата нпр. бушењу малим електричним бушилицама и одвртачима
VIŠESTEPENO DOVOĐENJE VAZDUHA PO VISINI LOŽIŠTA KAO PRIMARNA MERA REDUKCIJE AZOTNIH OKSIDA
No full textTemu ovog rada predstavlja istraživanje složenih procesa u ložištu parnog kotla koji
funkcioniše sa višestepenim dovođenjem vazduha po visini ložišta, kao glavnom primarnom merom
redukcije azotnih oksida. Ova kompleksna oblast još uvek nije dovoljno istražena, naročito u
domenu uticaja nove šeme sagorevanja na toplotni proces u ložištu i rad parnog kotla u celini.
Prikazanim istraživanjem afirmisan je pristup primene numeričkih proračuna izdvojenog elementa
složenog energetskog sistema čime je omogućeno definisanje glavnih pravaca promena koje su
nastale u ložištu sa novom organizacijom sagorevanja, što je rezultiralo mogućnošću proširenja
normativnih inženjerskih metoda.
Proširenje postojećih projektnih jednodimenzijskih procedura, izvorno namenjenih samo
nadstehiometrijskim uslovima rada, izvršeno je definisanjem glavnih uticajnih parametara na
procese u domenu gde se sagorevanje odvija u uslovima nedostatka kiseonika. Na ovakav način
dopunjena metodologija omogućila je primenu integralnih proračuna koji kao takvi zahtevaju
skromnije računarske kapacitete i neuporedivo manji utrošak vremena uz značajno suženje
prostora za računsku grešku. Potvrdom rezultata proračuna sa radnim parametrima na realnim
termoenergetskim postrojenjima stvoreni su uslovi za proširenje oblasti primene jednodimenzijskih
modela. Ovim je ujedno i sačuvano, u oblasti primenjenih inženjerskih metoda, akumulirano
iskustvo u projektovanju i praćenju rada energetskih parnih kotlova.
Jedan od glavnih ciljeva sprovedenog istraživanja je da se ovakva metodologija može primeniti
za ispitivanje mogućnosti produženja radnog veka energetskih postrojenja u Republici Srbiji
koja su u eksploataciji preko 30 godina. Kako bi zadovoljili sve strože ekološke norme koje se
odnose na sadržaj azotnih oksida postojeći sistemi moraju implementirati nove koncepcije sagorevanja.
Ovakve procedure mogu se primeniti i za proveru radnih parametara novih postrojenja, na
način na koji se to danas ne vrši, sa mogućnostima ispitivanja mera za povećanje njihove sigurnosti
i efikasnosti.
Prikazani model primenjen je za procenu radnih uslova energetskih parnih kotlova u Republici
Srbiji, koji rade sa novim šemama organizacije sagorevanja primarnim merama redukcije
azotnih oksida. Ovim radom biće prezentovani i rezultati procene rada uzornog energetskog parnog
kotla nakon implementacije nove šeme sagorevanja, za različita opterećenja pri promeni mesta i količine vazduha koja se uvodi po visini njegovog ložišta, a koji predstavljaju osnov za optimizaciju
procesa u celini.ugovor br. 451-03-65/2024-03/200105 i ugovor broj 451-03- 66/2024-03/ 200105 od 5.2.2024