Methodological problems of the application of renewable energy sources in cultural heritage protection

Heritologija kao nauka o zaštiti kulturnog nasleđa, multidisciplinarna je oblast, u kojoj pitanje energije ima izuzetan značaj u domenu zaštite nepokretnog kulturnog nasleđa, odnosno arheoloških lokaliteta. Modeli savremene prezentacije nasleđa zasnovani su na primeni novih tehnologija, kao i na ekološkoj bezbednosti u koju je uključena i primena obnovljivih izvora energije. U ovom radu istražuju se metodološki problemi u formulisanju paradigme zasnovane na principima intentio operis i intentio auctoris, koja u projektovanju modela prezentacije kulturnog nasleđa uvažava pitanja jedinstvenosti, originalnosti i ekskluziviteta autorskih prostornih rešenja, zbog čega je veoma osetljivo i pitanje modela primene obnovljivih izvora energije.Heritology, as a science for the protection of cultural heritage, is a multidisciplinary field in which the issue of energy is of great importance in terms of protection of immovable cultural herit-age, that is, archaeological sites. Models of contemporary heritage presentation are based on the application of new technologies, as well as on environmental safety, which includes the use of re-newable energy sources. This paper explores methodological problems of formulating a paradigm based on the principles of intentio operis and intentio auctoris, which in designing a model for the presentation of cultural heritage takes into account the uniqueness, originality and exclusivity of author's spatial solutions, which makes the model of renewable energy application very sensitive

Analysis of the estimated remaining service life of gas rectification columns

Gas rectification columns are process apparatuses which are very important part of each onshore plant. Sudden failure of these types of columns causes huge daily losses, while fluid leakage can be very dangerous for the people and hazardous for the environment. For that reason, a regular and correct examination of the column is of great importance for the continual process of leading. Together with the detailed examination of the column, a risk-based inspection was applied to maximize savings, both material, time, and costs. The expected remaining service life of rectification columns was also analyzed, while the corrosion rates were calculated according to the various international standards. The minimum required column wall thickness was calculated according to the most commonly used international standard and the obtained difference was analyzed. Detailed analysis of the total risks of the column due to potential failure is presented

Digital image correlation method in experimental analysis of fracture mechanics parameters

U okviru rada su predstavljeni principi i primeri savremenih eksperimentalnih metoda za određivanje parametara mehanike loma. Metodologija analize i određivanja parametara mehanike loma obuhvatila je analizu ponašanja metalnih materijala u odnosu na lom primenom modifikovanih epruveta mehanike loma, sa inicijalnom prslinom i zateznim opterećenjem, i imala je za cilj pre svega određivanje karaktera tih procesa u slučaju problema tankih pločica, uz korišćenje osnovnih postulata mehanike loma. Metodologija uključuje primenu eksperimentalnih postupaka mehanike loma definisanih standardima, uz primenu metode za trodimenzionalno stereoskopsko merenje mehaničkog ponašanja materijala. Pomoću sistema za korelaciju digitalnih slika (Digital Image Correlation, DIC) za ispitivanje deformacija i pomeranja u materijalu ispitani su parametri mehanike loma metalnih materijala, pre svega epruveta od 316L nerđajućeg čelika i titan legure Ti-6Al-4V. 3D optički sistem GOM i softver Aramis su korišćeni za izvođenje eksperimentalne analize na pripremljenim epruvetama. Pošto se ovaj sistem koristi za merenje deformacija i parametra pomeranja otvaranja vrha prsline CTOD na modifikovanim kompaktnim epruvetama za zatezanje C(T) i epruvetama sa zarezom, dat je i kratak pregled mernih procedura i procesiranja rezultata, kao i moguće primene ovog sistema. Prikazani rezultati daju pregled polja deformacija i pomeranja tokom otvaranja vrha prsline, rasta prsline i u trenutku loma epruvete, što nije moguće putem tradicionalnih metoda merenja. Analizom rezultata pokazano je da je sa velikom preciznošću moguće izmeriti pomeranja tokom otvaranja vrha prsline i dobiti CTOD parametar. Rezultati pokazuju da odabrana metoda pruža dobre rezultate u analizi mehaničkog ponašanja i određivanju parametara mehanike loma metalnih materijala.The principles and examples of state-of-the-art experimental methods for measuring the fracture mechanics parameters are presented in this paper. The methodology of experimental analysis of the fracture mechanics parameters includes investigation of fracture behaviour of metallic materials using modified specimens with initial crack under tensile load, with the primary goal of determining the characteristics of fracture processes for the case of thin plates, using basic fracture mechanics postulates. The methodology also includes the application of experimental fracture mechanics procedures as defined by standards, using three-dimensional stereo-metric mechanical behaviour measurement methods. Fracture behaviour of metallic materials, mainly 316L stainless steel and titanium alloy Ti-6Al-4V specimens, is analyzed by using a digital image correlation (DIC) system for measuring strain and displacement in the material. GOM three-dimensional optical system and Aramis software are used to perform experimental analysis of selected specimens. As this system is used to measure strain and crack tip opening displacement (CTOD) parameter on the modified compact tension specimen C(T) and notch specimens, a basic review of measuring procedures and result processing is given, alongside other possible applications for this system. The presented results show strain and displacement fields during crack tip opening, crack growth, and the moment of fracture of specimens, which are not possible using traditional measurement methods. The analysis of results shows that it is possible to measure displacements during crack tip opening with a great precision, and thus obtain the CTOD parameter. The results show that the selected measuring method obtains good results in the analysis of mechanical behaviour and fracture mechanics parameters of metallic materials

Integrity assessment of tanks with microcracks in welded joints

Tokom eksploatacije rezervoara za skladištenje tečnog ugljendioksida ukazala se potreba za ugradnjom dva nova priključka u jedno od danaca. Rezervoar je izrađen od mikrolegiranog čelika, a priključci od visokolegiranog austenitnog čelika. Za izradu novih priključaka izabrani su isti dodatni materijali i ista tehnologija zavarivanja, koji su korišćeni i pri izradi rezervoara. Ispitivanjima metodama bez razaranja zavarenih spojeva novih priključaka otkrivene su mikroprsline u zoni uticaja toplote mikrolegiranog čelika. Primenom postupka prikazanom u standardu BSI PD 6493 'Uputstvo za ocenu prihvatljivosti grešaka u zavarenim konstrukcijama', ocenjen je uticaj ovih mikroprslina na integritet zavarenih spojeva novih priključaka i time i na integritet rezervoara.During the exploitation of tanks used for storing liquid carbon dioxide there was a need to install two new connectors on one of the lids. The tank is made of micro-alloyed steel and its connectors are made of high-alloyed austenite steel. The same welding technology and added materials are used for both the tank and connectors. Non-destructive testing methods of welded joints in new connectors revealed microcracks in the heat-affected zone of micro-alloyed steel. By applying the procedure given in standard BSI PD 6493 'Manual for assessment of acceptability of flaws in welded structures', it is possible to estimate the effect of these microcracks on the integrity of welded joints in new connectors, and therefore their effect on the integrity of the tank

Surface modification of laser welded nimonic 263 sheets

Laser surface treatment is both a thermomechanical and mechanical process, based on the ability of a high energy laser pulse to generate shock waves and plastic deformation in metallic materials. Laser welding is a high energy density process with many advantages such as narrow heat affected zone, lower heat input and lower heat/energy distortion compared to conventional welding processes. In this paper, Nimonic 263 alloy sheets are laser welded by Nd:YAG laser using different laser processing parameters. The microstructure, surface roughness and mechanical properties are investigated. Welded joints are mechanically treated by laser in order to improve the surface and mechanical characteristics. Mechanical characteristics are determined by tensile test, and fractures and laser treated weld surfaces are observed by scanning and optical microscopy. Surface topography is analysed by optical profilometry and micro hardness is measured by Vickers method

Digital image correlation method in experimental analysis of fracture mechanics parameters

U okviru rada su predstavljeni principi i primeri savremenih eksperimentalnih metoda za određivanje parametara mehanike loma. Metodologija analize i određivanja parametara mehanike loma obuhvatila je analizu ponašanja metalnih materijala u odnosu na lom primenom modifikovanih epruveta mehanike loma, sa inicijalnom prslinom i zateznim opterećenjem, i imala je za cilj pre svega određivanje karaktera tih procesa u slučaju problema tankih pločica, uz korišćenje osnovnih postulata mehanike loma. Metodologija uključuje primenu eksperimentalnih postupaka mehanike loma definisanih standardima, uz primenu metode za trodimenzionalno stereoskopsko merenje mehaničkog ponašanja materijala. Pomoću sistema za korelaciju digitalnih slika (Digital Image Correlation, DIC) za ispitivanje deformacija i pomeranja u materijalu ispitani su parametri mehanike loma metalnih materijala, pre svega epruveta od 316L nerđajućeg čelika i titan legure Ti-6Al-4V. 3D optički sistem GOM i softver Aramis su korišćeni za izvođenje eksperimentalne analize na pripremljenim epruvetama. Pošto se ovaj sistem koristi za merenje deformacija i parametra pomeranja otvaranja vrha prsline CTOD na modifikovanim kompaktnim epruvetama za zatezanje C(T) i epruvetama sa zarezom, dat je i kratak pregled mernih procedura i procesiranja rezultata, kao i moguće primene ovog sistema. Prikazani rezultati daju pregled polja deformacija i pomeranja tokom otvaranja vrha prsline, rasta prsline i u trenutku loma epruvete, što nije moguće putem tradicionalnih metoda merenja. Analizom rezultata pokazano je da je sa velikom preciznošću moguće izmeriti pomeranja tokom otvaranja vrha prsline i dobiti CTOD parametar. Rezultati pokazuju da odabrana metoda pruža dobre rezultate u analizi mehaničkog ponašanja i određivanju parametara mehanike loma metalnih materijala.The principles and examples of state-of-the-art experimental methods for measuring the fracture mechanics parameters are presented in this paper. The methodology of experimental analysis of the fracture mechanics parameters includes investigation of fracture behaviour of metallic materials using modified specimens with initial crack under tensile load, with the primary goal of determining the characteristics of fracture processes for the case of thin plates, using basic fracture mechanics postulates. The methodology also includes the application of experimental fracture mechanics procedures as defined by standards, using three-dimensional stereo-metric mechanical behaviour measurement methods. Fracture behaviour of metallic materials, mainly 316L stainless steel and titanium alloy Ti-6Al-4V specimens, is analyzed by using a digital image correlation (DIC) system for measuring strain and displacement in the material. GOM three-dimensional optical system and Aramis software are used to perform experimental analysis of selected specimens. As this system is used to measure strain and crack tip opening displacement (CTOD) parameter on the modified compact tension specimen C(T) and notch specimens, a basic review of measuring procedures and result processing is given, alongside other possible applications for this system. The presented results show strain and displacement fields during crack tip opening, crack growth, and the moment of fracture of specimens, which are not possible using traditional measurement methods. The analysis of results shows that it is possible to measure displacements during crack tip opening with a great precision, and thus obtain the CTOD parameter. The results show that the selected measuring method obtains good results in the analysis of mechanical behaviour and fracture mechanics parameters of metallic materials

Welding safety by using a new model of welders' recertification in the oil and gas industry

The paper presents a solution applied for determining the quality of the welding process in oil and gas industrial plants, as well as reliable verification of professional qualification of welding personnel. By applying the solution, welded joint quality can increase and thus the safety (especially in the field of high-pressure gas plants) and the reliability of the process in oil and gas-, petrochemical and nuclear plants, as a whole. The paper analyses safety aspects in the welding process, depending on the competence in welding and an appropriate qualification, taking into account that high levels of skill and competence are required where safety-critical items are fabricated. The results in the application of the new recertification model are presented and analysed, and it is emphasized that the areas of application of the new solution are wide, mainly applied in the oil and gas-, petrochemical industry, and the construction of nuclear plants. The application of the new model of Welders Recertification enables project savings, but also safety at work since the employer has a constant insight into the qualifications and welding capabilities of each welder

Gasification of wastes and residues for electricity production

Gasification technology presents one of the promising options for converting biomass energy into electricity. Gasification process converts carbonaceous materials into carbon-monoxide, hydrogen, carbon-dioxide, and gaseous hydrocarbons (producer gas). Producer gas can be supplied as fuel to the internal combustion engines and power generators. In order to maximize the efficiency of biomass conversion, producer gas should be utilized not only for power generation but also for thermal production from the producer gas sensible heat. In this paper, one of common types of agricultural residues, in Serbia, corn cob and corn stalks, were compared with wood chips and analysed in order to evaluate their possible utilisation for electric and thermal energy production. Plant consists of downdraft gasification unit coupled with gas engine. Modelling results show that for 1000kg of dry biomass can be produced: 1566 kWe and 1016 kWth (for wood chips material with HHV=19.70 MJ/kg); 11142 kWe and977.8 kWth (for corn cob HHV=19.25 MJ/kg); 1399 kWe and 960.4 kWth (for corn stalks with HHV=17.31 MJ/kg)

Welding safety by using a new model of welders' recertification in the oil and gas industry

The paper presents a solution applied for determining the quality of the welding process in oil and gas industrial plants, as well as reliable verification of professional qualification of welding personnel. By applying the solution, welded joint quality can increase and thus the safety (especially in the field of high-pressure gas plants) and the reliability of the process in oil and gas-, petrochemical and nuclear plants, as a whole. The paper analyses safety aspects in the welding process, depending on the competence in welding and an appropriate qualification, taking into account that high levels of skill and competence are required where safety-critical items are fabricated. The results in the application of the new recertification model are presented and analysed, and it is emphasized that the areas of application of the new solution are wide, mainly applied in the oil and gas-, petrochemical industry, and the construction of nuclear plants. The application of the new model of Welders Recertification enables project savings, but also safety at work since the employer has a constant insight into the qualifications and welding capabilities of each welder

Analysis of the estimated remaining service life of gas rectification columns

Gas rectification columns are process apparatuses which are very important part of each onshore plant. Sudden failure of these types of columns causes huge daily losses, while fluid leakage can be very dangerous for the people and hazardous for the environment. For that reason, a regular and correct examination of the column is of great importance for the continual process of leading. Together with the detailed examination of the column, a risk-based inspection was applied to maximize savings, both material, time, and costs. The expected remaining service life of rectification columns was also analyzed, while the corrosion rates were calculated according to the various international standards. The minimum required column wall thickness was calculated according to the most commonly used international standard and the obtained difference was analyzed. Detailed analysis of the total risks of the column due to potential failure is presented