Residual life estimation of a thermal power plant component: The high-pressure turbine housing case

This study focuses on the estimation of residual life of damaged thermal power plant components. The high-pressure turbine housing was chosen as an example of thermal power plant component where, during the years of exploitation, damage appeared in the form of dominant crack. Residual life estimation procedure, based upon experimental and numerical methods has been introduced and applied. Material properties were determined experimentally both at room and operating temperature, while all necessary calculations were performed by the special finite element method, so-called X-FEM. The residual life estimation of the damaged high-pressure turbine housing was performed by applying the Paris's law for crack growth analysis

Numerical analysis of the penetration process of a 30mm armor-piercing projectile

Introduction/purpose: Thin plates made of high–strength steel are frequently used both in civil and military ballistic protection systems. In order to choose an appropriate type of alloy, it is necessary to fulfil a number of criteria, such as the condition of use, the desired ballistic performance, weight, dimensions, and price. This paper presents a numerical analysis of the penetration of a 30mm armor-piercing projectile with a velocity of 750m/s into steel alloy Weldox 460 plates of different thicknesses at a distance of 1000m . Methods: The analysis has been performed using numerical methods and finite element modeling to calculate stresses and deformation caused by the penetration effect. For defining material characteristics, the JohnsonCook material model and the fracture of materials model have been used. In this paper, the software packages FEMAP and LS Dyna have been used for defining models and performing numerical calculations. Results: The results of the performed numerical analysis as well as the obtained stress and displacement values are presented for four different armor plate thicknesses: 30mm, 33mm, 34mm, and 40mm. The results show a penetration effect and an interaction between the projectile and the armor plate. Conclusion: Modeling the impact on armor-piercing obstacles is very complex, extensive, and demanding, and the formed models approximate the real problem of projectile penetration in a very successful way (or with a certain deviation). In recent times, the analysis using the finite element method has proven to be one of effective approaches to solving such and similar problems. The material and the dimensions of the obstacle, as well as the material and the ballistic parameters of the projectile have the greatest influence on projectile penetration. Keeping all the input parameters at the same level and increasing the thickness of the target leads to its increased resistance to penetration

The analytical capability of laser induced breakdown spectroscopy (LIBS) based on tea CO2 laser system

This paper gives an overview of analytical capabilities of the laser induced breakdown spectroscopy (LIBS) system, based on Transversely-Excited Atmospheric pressure (TEA) CO2laser, and time-integrated, spatially-resolved detection, for the analysis of solid materials. The developed LIBS system is unique, and differs from the commonly used systems in two respects. The first one is the laser used as an energy source for plasma generation, and the second one is the applied non-gated detection scheme. Various types of materials were analyzed, from metals to biological samples, under different experimental conditions. The obtained results were critically evaluated and compared to the results obtained using commercially available LIBS that comprises Nd:YAG laser and time-gated detection.It was concluded that when it comes to detectability, precision and sensitivity, this simple and cost effective LIBS system may be regarded highly competitive to standard LIBS systems.Physical chemistry 2016 : 13th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-30 September 2016

LIBS Analysis of Geomaterials: Comparative Study of Basalt Plasma Induced by TEA CO2 and Nd:YAG Laser in Air at Atmospheric Pressure

We present a study of the plasma generated by transversely excited atmospheric (TEA) CO2 laser irradiation of a basalt sample. The plasma was induced in air at atmospheric pressure. The same sample was also analyzed using a commercial LIBS system based on Nd:YAG laser and time-gated detection. The main plasma parameters, temperature, and electron number density were determined and analytical capabilities of the two systems compared. Despite differences in laser wavelength, pulse duration, applied fluence, and signal detection scheme, the two systems are comparable in terms of element detectability and limits of detection. In both cases, all elements usually present in geological samples were identified. The estimated limits of detection for most elements were below 100 ppm, while for Cu, Cr, and Sr they were around or below 10 ppm. The obtained results led to the conclusion that simple, cost- effective TEA CO2 LIBS system can find applications for geological explorations

Determination of low alloying elements concentrations in cast iron by laser induced breakdown spectroscopy based on TEA CO2 laser system

The analytical capability of laser-produced plasma for the analysis of low alloying elements in cast iron samples has been investigated. The plasma was induced by irradiation of a sample in air at atmospheric pressure using an infrared CO2 laser. Emission spectra were recorded by time-integrated spatially-resolved measurement technique. A set of ten cast iron samples in a powder or particulate form were provided by BAM (Bundesanstalt fur Material Forschung und Prufung, Deutschland), seven of which were used for calibration, and three were treated as unknowns. Linear calibration curves were obtained for copper, chromium, and nickel, with correlation coefficients above 0.99. Precision and accuracy of the LIBS method was evaluated and compared to those obtained by the inductively coupled plasma (ICP) analysis of the same samples. Detection limits for Cu, Cr and Ni were close to those reported in the literature for other comparable iron-based alloys obtained using different LIBS systems. Analytical figures of merit of the studied LIBS system may be considered as satisfying, especially in the light of other advantages of the method, like cost effective and fast analysis with no sample preparation, and with a possibility for real-time on-site analysis

Supplementary material for the article: Izrael-Živković, L.; Rikalović, M.; Gojgić-Cvijović, G.; Kazazić, S.; Vrvić, M.; Brčeski, I.; Beškoski, V.; Lončarević, B.; Gopčević, K.; Karadžić, I. Cadmium Specific Proteomic Responses of a Highly Resistant: Pseudomonas Aeruginosa San Ai. RSC Advances 2018, 8 (19), 10549–10560. https://doi.org/10.1039/c8ra00371h

Supplementary material for: [https://doi.org/10.1039/c8ra00371h]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2118

Cadmium specific proteomic responses of a highly resistant Pseudomonas aeruginosa san ai

Pseudomonas aeruginosa san ai is a promising candidate for bioremediation of cadmium pollution, as it resists a high concentration of up to 7.2 mM of cadmium. Leaving biomass of P. aeruginosa san ai exposed to cadmium has a large biosorption potential, implying its capacity to extract heavy metal from contaminated medium. In the present study, we investigated tolerance and accumulation of cadmium on protein level by shotgun proteomics approach based on liquid chromatography and tandem mass spectrometry coupled with bioinformatics to identify proteins. Size exclusion chromatography was used for protein prefractionation to preserve native forms of metalloproteins and protein complexes. Using this approach a total of 60 proteins were observed as up-regulated in cadmium-amended culture. Almost a third of the total numbers of up-regulated were metalloproteins. Particularly interesting are denitrification proteins which are over expressed but not active, suggesting their protective role in conditions of heavy metal exposure. P. aeruginosa san ai developed a complex mechanism to adapt to cadmium, based on: extracellular biosorption, bioaccumulation, the formation of biofilm, controlled siderophore production, enhanced respiration and modified protein profile. An increased abundance of proteins involved in: cell energy metabolism, including denitrification proteins; amino acid metabolism; cell motility and posttranslational modifications, primarily based on thiol-disulfide exchange, were observed. Enhanced oxygen consumption of biomass in cadmium-amended culture versus control was found. Our results signify that P. aeruginosa san ai is naturally well equipped to overcome and survive high doses of cadmium and, as such, has a great potential for application in bioremediation of cadmium polluted sites.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3179

Supplementary material for the article: Izrael-Živković, L.; Rikalović, M.; Gojgić-Cvijović, G.; Kazazić, S.; Vrvić, M.; Brčeski, I.; Beškoski, V.; Lončarević, B.; Gopčević, K.; Karadžić, I. Cadmium Specific Proteomic Responses of a Highly Resistant: Pseudomonas Aeruginosa San Ai. RSC Advances 2018, 8 (19), 10549–10560. https://doi.org/10.1039/c8ra00371h

Supplementary material for: [https://doi.org/10.1039/c8ra00371h]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2118

Singlet state formation and its impact on magnetic structure in tetramer system SeCuO3_3

We present an experimental investigation of the magnetic structure in a tetramer system SeCuO$_3$ using neutron diffraction and nuclear resonance techniques. We establish a non-collinear, commensurate antiferromagnetic ordering with a propagation vector $\textbf{k} = \left(0,0,1 \right)$. The order parameter follows a critical behavior near $T_N = 8$ K, with a critical exponent $\beta = 0.32$ in agreement with a 3D universality class. Evidence is presented that a singlet state starts to form on tetramers at temperatures as high as 200 K, and its signature is preserved within the ordered state through a strong renormalization of the ordered magnetic moment on two non-equivalent copper sites, $m_{Cu1} \approx 0.4 \mu_B$ and $m_{Cu2} \approx 0.7 \mu_B$ at 1.5 K

Standardized Aronia melanocarpa Extract as Novel Supplement against Metabolic Syndrome: A Rat Model

The aim of our study was to examine the effects of different dietary strategies, high-fat (HFd) or standard diet (Sd) alone or in combination with standardized oral supplementation (0.45 mL/kg/day) of Aronia melanocarpa extract (SAE) in rats with metabolic syndrome (MetS). SAE is an official product of pharmaceutical company Pharmanova (Belgrade, Serbia); however, the procedure for extraction was done by EU-Chem company (Belgrade, Serbia). Rats were divided randomly into six groups: control with Sd, control with Sd and SAE, MetS with HFd, MetS with HFd and SAE, MetS with Sd and MetS with Sd and SAE during 4 weeks. At the end of the 4-week protocol, cardiac function and liver morphology were assessed, while in the blood samples glucose, insulin, iron levels and systemic redox state were determined. Our results demonstrated that SAE had the ability to lower blood pressure and exert benefits on in vivo and ex vivo heart function. Moreover, SAE improved glucose tolerance, attenuated pathological liver alterations and oxidative stress present in MetS. Obtained beneficial effects of SAE were more prominent in combination with changing dietary habits. Promising potential of SAE supplementation alone or in combination with different dietary protocols in triggering cardioprotection should be further examined in future