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Number of results: 17
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Abstract

Assessing the level of metallurgical and foundry technology in prehistoric times requires the examination of raw material finds, including elongated ingots, which served as semi-finished products ready for further processing. It is rare to find such raw material directly at production settlements, but Wicina in western Poland is an exception. During the Hallstatt period (800-450 BC), this area, situated along the middle Oder River, benefited from its favorable location in the heart of the Central European Urnfield cultures and developed networks for raw material exchange and bronze foundry production. Numerous remnants of casting activities, such as clay casting molds, casting systems, and raw materials, have been discovered at the Wicina settlement. This article aims to provide an archaeometallurgical interpretation of raw material management and utilization by prehistoric communities during the Early Iron Age. To achieve this, a collection of 31 ingots from the defensive settlement in Wicina, along with two contemporary deposits from Bieszków and Kumiałtowice, both found within a 20 km radius of the stronghold, were studied. Investigations were conducted using a range of methods, including optical microscopy(OM), scanning electron microscopy (SE M), energy-dispersive X-ray spectroscopy (SE M-EDS), X-ray fluorescence spectroscopy (ED-XRF), powder X-ray diffraction (PXRD), AAS and ICP-OES spectrometer. The significance of ingots is examined in the context of increasing social complexity and the rising popularity of bronze products, which necessitated diversified production and a demand for raw materials with different properties and, consequently, different chemical compositions.
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Authors and Affiliations

A. Garbacz-Klempka
1
ORCID: ORCID
K. Dzięgielewski
2
ORCID: ORCID
M. Wardas-Lasoń
3
ORCID: ORCID

  1. AGH University Of Krakow, Faculty of Foundry Engineering, Historical Layers Research Centre, ul. Reymonta 23, 30-059 Krakow, Poland
  2. Jagiellonian University, Institute of Archaeology, ul. Gołębia 11, 31-007 Krakow, Poland
  3. AGH University Of Krakow, Faculty of Geology, Geophysics And Environmental Protection, Historical Layers Research Centre, al. Mickiewicza 30, 30-059 Krakow, Poland
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Abstract

The paper addresses the macro- and microsegregation of alloying elements in the new-developed Mn-Al TRIP steels, which belong to the third generation of advanced high-strength steels (AHSS) used in the automotive industry. The segregation behaviour both in the as-cast state and after hot forging was assessed in the macro scale by OES and by EDS measurements in different structural constituents. The structural investigations were carried out using light and scanning electron microscopy. A special attention was paid to the effect of Nb microaddition on the structure and the segregation of alloying elements. The tendency of Mn and Al to macrosegregation was found. It is difficult to remove in Nb-free steels. Microsegregation of Mn and Al between austenite and ferritic structural constituents can be removed.

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Authors and Affiliations

A. Grajcar
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Abstract

In this case ceramic layers from Metco ZrO2 and Al2O3 powders mixture (25/75; 50/50 and 75/25) were obtained through atmospheric plasma spraying (APS) after five passes on low carbon steel substrate. The sample surfaces mechanically grinded (160-2400) before and after ceramic layer deposition. Powder’s mixtures and the surface of ceramic thin layers were analyzed through: scanning electron microscopy (SEM). In order to understand the effect of surface wettability of the ceramic layers, before and after grinding the surface, three different liquids were used. Experimental results confirm the modification of the steel substrate surface characteristic from hydrophilic to hydrophobic when the ceramic layer was deposited. Surface free energy of hydration increases for all the samples with zirconia percentage addition before polishing process.
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Authors and Affiliations

M. Luțcanu
1 2
ORCID: ORCID
M. Coteață
3
ORCID: ORCID
M.A. Bernevig
1
ORCID: ORCID
C.D. Nechifor
2
ORCID: ORCID
M.M. Cazacu
2
ORCID: ORCID
P. Paraschiv
4
ORCID: ORCID
B. Istrate
5
ORCID: ORCID
G. Bădărău
1
ORCID: ORCID
I.G. Sandu
1
ORCID: ORCID
N. Cimpoeșu
1
ORCID: ORCID

  1. Gheorghe Asachi Technical University of Iasi, Faculty of Materials Science and Engineering, Prof.dr.doc. D. Mangeron no. 41 Street, 700050 Iasi, Romania
  2. "Gheorghe Asachi” Technical University of Iasi, Department of Physics, 700050 Iasi, Romania
  3. Gheorghe Asachi Tech Univ Iasi, Dept Machine Mfg Technol, 59A D Mangeron Blvd, Iasi 700050, Romania
  4. “Gheorghe Asachi” Technical University of Iasi, Department of Sport, 700050 Iasi, Romania
  5. Gheorghe Asachi Tech Univ Iasi, Fac Mech Engn 43 D Mangeron St, Iasi 700050, Romania
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Abstract

This paper is focused on investigating the mechanisms associated with different failure modes of copper (C101) sandwich panels with honeycomb cores of different heights subjected to flexural loading. Honeycomb core is made up of copper strips which were formed to required shapes using Dies fabricated by Electric Discharge Wire cut machining technique. All the joints in the sandwich panel were established through Brazing technique. Three-point bending test was conducted as per ASTM standard C-393. It was observed that increase in height of the core resulted in panels with higher strength to weight ratio. It also exhibited higher stiffness to weight ratio and very high strain energy absorption ability. An increase in flexural strength was reported with a maximum of 43% improvement for 10.9 mm core compared to 6.9 mm core. Further, 81.75% increase in absorbed strain energy was reported for 10.9 mm thick panel compared to 6.9 mm. The Optical and scanning electron microscope (SEM) analysis confirmed the establishment of good bonding between the filler and the substrate. Energy-dispersive Spectroscopic (EDS) analysis revealed the presence of Cu, Al, Zn, SiO2 and CaCO3 in the substrate. Further it also revealed the presence of Cu, CaCO3 and GaP in the filler material. The failure mode map was constructed which can be used for predicting different types of failures more likely to occur for specific parameters of copper sandwich panel. The dominant failures occurred during testing was in good agreement with the prediction done through failure mode map. The appreciable results in the proposed research may be supportive in construction of cooling system. The structure development and process control are convenient in mass production in automobile industries.
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Authors and Affiliations

A. Vino
1
ORCID: ORCID
K. Kalaichelvan
1
ORCID: ORCID
S. Sajith
2
ORCID: ORCID
G. Kumaresan
3
ORCID: ORCID

  1. Anna University, Department of Ceramics, AC Techcampus, Chennai, India
  2. Anna University, Department of Aerospace Engineering, MIT Campus, Chennai, India
  3. Bannari Amman Institute of Technology, Department of Mechanical Engineering, Sathya Mangalam, Erode – 638 401, India
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Abstract

The subject of the research was the Middle Miocene red algal limestone from the Włochy deposit, which is currently the only place of exploitation of the Pińczów Limestone representing a local type of the Leitha Limestone. The collected samples of this rock belong to the organodetric facies of diverse grain size and sorting of clastic material. Considering the proportions of characteristic skeleton remains, the composition of the coarse-grained organodetric facies is red algal-foraminiferalbryozoic, while of the fine-grained facies is foraminiferal-red algal. The cement of these rocks is predominantly sparite compared to micrite-clay matrix. A complement to petrographic studies was the chemical analysis and identification of mineral phases with X-ray diffraction. Moreover, physical and mechanical properties of samples were analyzed. Porosity of the rock was assessed in the polarizing and scanning microscope (SEM-EDS) observations, as well as with a porosimetric tests. The coarse-detrital limestone with a dominant binder in the form of intergranular cement is characterized by the apparent density sometimes exceeded 1.90 Mg/m3, while fine-grained limestone has the highest water absorbability (above 20%) and total porosity (about 40%). The above properties influenced high water absorption by capillarity, limiting the possibility of using limestone in places exposed to moisture. The observed relationship between the ultrasonic waves velocity and the uniaxial compressive strength gives the possibility of predicting the value of the latter parameter in the future. The limestones from Włochy deposit do not differ in quality from the previously used Pińczów Limestones, and their technical parameters predestine them for use as cladding material with insulating properties.

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Authors and Affiliations

Beata Figarska-Warchoł
Grażyna Stańczak
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Abstract

The paper addresses the microsegregation of Mn, Mo, Cr, W, V, Si, Al, Cu and P in the white cast iron. Eutectic alloy with the content of 4.25% C was studied. The white cast iron was directionally solidified in the vacuum Bridgman-type furnace at a constant pulling rate v = 83 μm/s and v = 167 μm/s and at a constant temperature gradient G = 33.5 K/mm. The microstructural research was conducted using light and scanning electron microscopy. The microsegregation of elements in ledeburite was evaluated by EDS measurements. Content of elements in ledeburitic cementite and ledeburitic pearlite was determined. The tendency of elements to microsegregation was found dependent on the solidification rate. Microsegregation of elements between pearlite and cementite structural constituents has been specified. The effect of solidification rate on the type and intensity of microsegregation in directionally solidified eutectic white cast iron was observed. A different type of microsegregation was observed in the components of ledeburite in cementite and pearlite.
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Bibliography

[1] Podrzucki, Cz. (1991). Cast iron. Structure. Properties. Application T.1 and T.2, First Edition, Publishing house ZG STOP. (in Polish)
[2] Sękowski, K. (1973). Heterogeneity of the chemical composition of the metal matrix of ductile iron. Foundry Review. 8-9, 205-255413. (in Polish)
[3] Pietrowski, S. (1987). The influence of the chemical composition of nodular cast steel and cast iron and casting cooling rate on the austenite transformation to acicular structures. Scientific Books nr 94: Technical University of Łódź. (in Polish)
[4] Pietrowski, S. & Gumienny, G. (2006). Crystallization of nodular cast iron with additions of Mo, Cr, Cu and Ni. Archives of Foundry. 6(22), 406-413. (in Polish)
[5] Pietrowski, S. & Gumienny, G. (2012). Microsegregation in nodular cast iron with carbides. Archives of Foundry Engineering. 12(4), 127-134. DOI: 10.2478/v10266-012-0120-z.
[6] Sandoz, G. (1968). Recent Research in Cast Iron, H. Marchant, ed. New York: Gordon and Breach, 509.
[7] Malinochka, Ya.N., Maslenkov, S.B. & Egorshina, T.V. (1963). Investigation of microsegregation in cast iron using electron microprobe. Liteinoe Proizvodstvo, 1, 22-25. (in Russ.)
[8] Swindelsand, N. & Burke, J. (1971). Silicon microsegregation and first stag graphitization in white cast irons. Metallurgical Transactions. 2, 3257-3263. DOI: 10.1007/BF02811605
[9] Charbonnier, J. & Margerie, J.C. (1967). Nouvelle contribution al’etude generale des mikrosegregation dans les alliages Fe-C du type ”fonte”. Fonderie. 259, 333-344.
[10] Bazhenov, V.E., & Pikunov, M.V. (2018) Microsegregation of silicon in cast iron. Izvestiya. Ferrous Metallurgy. 61(3), 230-236. DOI: 10.17073/0368-0797-2018-3-230-236 (in Russ.)
[11] Park, J.Y. and other (2002). Effect of Mn negative segregation through the thickness direction on graphitization characteristics of strip-cast white cast iron. Scripta Materialia 46(3), 199-203. https://doi.org/10.1016/S1359-6462(01)01220-9
[12] Dojka, M. & Stawarz, M. (2020). Bifilm defects on Ti-inculated chromium white cast iron. Materials. 13(14), 3124. https://doi.org/10.3390/ma13143124
[13] Trepczyńska-Łent, M. (1997). Spheroidizing annealing of whitened ductile iron. 1st National Scientific Conference "Materials Science - Foundry - Quality", 129-137, Krakow. (in Polish)
[14] Trepczyńska-Łent, M. (1998). Microsegregation of silicon and manganese after spheroidizing annealing in cast iron with spherical graphite. Scientific Journals ATR 216, Mechanics. 43, 217-226. Bydgoszcz (in Polish).
[15] Chang, W.S. & Lin, C.M. (2013). Relationship between cooling rate and microsegregation in bottom-chilled directionally solidified ductile irons. Journal of Mining and Metallurgy, Section B: Metallurgy. 49(3)B, 315-322. https://doi.org/10.2298/JMMB120702034C.
[16] Trepczyńska-Łent, M. Boroński D. & Maćkowiak P. (2021). Mechanical properties and microstructure of directionally solidified Fe-4.25%C eutectic alloy. Materials Science and Engineering A, 822(3) 141644. https://doi.org/10.1016/j.msea.2021.141644.
[17] Trepczyńska-Łent, M. (2017). Interphase spacing in directional solidification of white carbide eutectic, METAL 2017 - 26th International Conference on Metallurgy and Materials, Conference Paper, Conference Proceedings Volume 2017-January 254-260. ISBN: 978-808729479-6.
[18] Trepczyńska-Łent, M. (2017). Directional solidification of Fe-Fe3C white eutectic alloy. Crystal Research and Technology 52(7) July 2017, 1600359, version of record online: 26 JUN 2017. DOI: 10.1002/crat.201600359.
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Authors and Affiliations

M. Trepczyńska-Łent
1
ORCID: ORCID
J. Seyda
1
ORCID: ORCID

  1. Bydgoszcz University of Science and Technology, Poland
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Abstract

In the latest period hundreds of concrete viaducts were built in Poland within a short time range. The cases of destruction of concrete road viaducts described by the author in the article concern in the construction of such structures in various parts of our country, such as central regions of Poland, Warmia-Masuria, south – east - a total of about 30 objects. The occurring phenomenon is related to the micro cracks of the cement matrix which are not visible on the surface of the elements and become visible only after the cyclic freezing process as a result of the standard F150 frost resistance test, the so-called the standard method according to Annex N to the PN-B-06265: 2018 standard. The destruction took an unprecedented course and aroused much discussion in the scientific community. This article summarizes this discussion and indicates the root cause of the destruction.

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Authors and Affiliations

Józef Jasiczak
ORCID: ORCID
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Abstract

Copper-based alloys with the addition of Al present excellent properties and can be considered a proper choice for applications as contact materials based on their good strength and fret resistance. Cu-Al alloys are used in different systems parts as bearings, gears and worm gears. The intention is to replace steel materials with new copper-based materials for parts that work in a possible explosive environment to reduce the possibility of spark appearance. Copper-berilyum alloys are known as non-sparking alloys and are used in different tools obtaining for environments with possible explosive gaseous. Results from the obtaining and analysis of a new alloy based on CuAlBe are given. The material was melted in a vacuum induction furnace from CuBe master alloy and high purity aluminium and cast into a metallic die. The alloys obtained were analyzed using EDS – energy dispersive spectroscopy for chemical composition, OM-optical and SEM-electronic microscopy for the microstructure, and the electro-corrosion resistance was tested using linear Tafel diagram and cyclic potentiometry.
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Authors and Affiliations

R.G Chelariu
1
ORCID: ORCID
N. Cimpoeșu
1
ORCID: ORCID
T.I. Birnoveanu
1
ORCID: ORCID
B. Istrate
2
ORCID: ORCID
C. Baciu
1
ORCID: ORCID
C. Bejinariu
1
ORCID: ORCID

  1. “Gheorghe Asachi” University of Iasi, Faculty of Materials Science Engineering, Prof.dr.doc. D. Mangeron Street, no. 41, Iași 700050, Romania
  2. “Gheorghe Asachi” University of Iasi, Faculty of Mechanical Engineering, Prof.dr.doc. D. Mangeron Street, No. 61-63, Iași 700050, Romania
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Abstract

The reaction of alkalis with aggregate containing reactive forms of silica (ASR) plays a significant role in shaping the durability of concrete, as the strongly hygroscopic reaction products generated lead to internal stress, causing its expansion and cracking. This study presents an extended analysis of corrosive processes occurring in mortars with reactive natural aggregate from Poland, using computed tomography and scanning microscopy methods. Numerous cracks in the grains and the surrounding cementitious matrix were observed, indicating a high degree of advancement of corrosive processes. Over time, the proportion of pores with reduced sphericity increased, indicating ongoing degradation of the mortars. The usefulness of computed tomography in studying the progress of ASR was demonstrated. Scanning microscopy confirmed that the cause of mortar degradation is the formed ASR gel with a typical composition, located within the volume of reactive grains, cracks propagating into the cementitious matrix, and accumulated in air voids.
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Authors and Affiliations

Justyna Zapała-Sławeta
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Abstract

Explosion protection is of particular importance for safety as explosions also endanger the health of workers due to the uncontrolled effects of flames and pressure, the presence of harmful reaction products and the consumption of oxygen in the ambient air breathed by workers. CuAlBe alloy is proposed as a solution for mechanical actuators such as gears that work in environments with possible explosive atmosphere. Made of CuBe master alloy and pure aluminum in a induction furnace the material present large grains in melted state. After the hot rolling (heated 600s at 900°C) of the ingots small variation of chemical composition was observed based on the oxidation of the material, appearance of small cracks on the edges and a preferential orientation of the grains along the lamination direction. Scanning electron microscopy (SEM) was used to characterize the microstructural states of CuAlBe as laminated and heat treated states.
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Authors and Affiliations

G.R. Chelariu
1
ORCID: ORCID
N. Cimpoeșu
1
ORCID: ORCID
P. Paraschiv
1
ORCID: ORCID
B.A. Prisecariu
2
ORCID: ORCID
I. Rusu
1
ORCID: ORCID
I. Știrbu
1
ORCID: ORCID
G.I. Sandu
1
ORCID: ORCID
M. Benchea
3
ORCID: ORCID
C. Bejinariu
1
ORCID: ORCID

  1. Gheorghe Asachi University of Iasi, Faculty of Materials Science and Engineering, 43 Dimitrie Mangeron str., 700050, Iasi
  2. “Grigore T. Popa” University of Medicine and Pharmacy, Iasi, Romania
  3. Gheorghe Asachi University of Iasi, Mechanica l Faculty, 43 Dimitrie Mangeron str., 700050, Iasi
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Abstract

Economic dispatch (ED) is an essential part of any power system network. ED is howto schedule the real power outputs from the available generators to get the minimum cost while satisfying all constraints of the network. Moreover, it may be explained as allocating generation among the committed units with the most effective minimum way in accordance with all constraints of the system. There are many traditional methods for solving ED, e.g., Newton-Raphson method Lambda-Iterative technique, Gaussian-Seidel method, etc. All these traditional methods need the generators’ incremental fuel cost curves to be increasing linearly. But practically the input-output characteristics of a generator are highly non-linear. This causes a challenging non-convex optimization problem. Recent techniques like genetic algorithms, artificial intelligence, dynamic programming and particle swarm optimization solve nonconvex optimization problems in a powerful way and obtain a rapid and near global optimum solution. In addition, renewable energy resources as wind and solar are a promising option due to the environmental concerns as the fossil fuels reserves are being consumed and fuel price increases rapidly and emissions are getting higher. Therefore, the world tends to replace the old power stations into renewable ones or hybrid stations. In this paper, it is attempted to enhance the operation of electrical power system networks via economic dispatch. An ED problem is solved using various techniques, e.g., Particle Swarm Optimization (PSO) technique and Sine-Cosine Algorithm (SCA). Afterwards, the results are compared. Moreover, case studies are executed using a photovoltaic-based distributed generator with constant penetration level on the IEEE 14 bus system and results are observed. All the analyses are performed on MATLAB software.
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Bibliography

[1] Zee-Lee Gaing, Particle swarm optimization to solving the economic dispatch considering the generator limits, IEEE Trans. Power Syst., vol. 18, pp. 1187–1195 (2003).
[2] Nidul Sinha, Chakrabarti R., Chattopadhyay P.K., Evolutionary programming techniques for economic load dispatch, IEEE Transactions on Evolutionary Computation, vol. 7, iss. 1, pp. 83–94 (2003).
[3] Jeyakumar D., Jayabarathi T., Raghunathan T., Particle swarm optimization for various types of economic dispatch problems, International Journal of Electrical Power Energy System, vol. 36, pp. 42–28 (2006).
[4] Leandro dos Santos Coelho, Chu-Sheng Lee, Solving economic load dispatch problems in power system using chaotic and Gaussian particle swarm optimization approaches, Elsevier, International Journal of Electrical Power and Energy Systems (IJEPES), vol. 30, iss. 5, pp. 297–307 (2008).
[5] Vishnu Prasad, Amita Mahor, Saroj Rangnekar, Economic dispatch using particle swarm optimization: A review, Renewable and Sustainable Energy Reviews, vol. 13, pp. 2134–2141 (2009).
[6] Kumar C., Alwarsamy T., Dynamic Economic Dispatch – A Review of Solution Methodologies, European Journal of Scientific Research, ISSN 1450-216X, vol. 64, no. 4, pp. 517–537 (2011).
[7] Deep K., Bansal J.C., Solving Economic Dispatch Problems with Valve-point Effects using Particle Swarm Optimization, J. UCS, vol. 18, no. 13, pp. 1842–1852 (2012).
[8] Timothy Ganesan, Pandian Vasant, Irraivan Elamvazuthy, A hybrid PSO approach for solving nonconvex optimization problems, Archives of Control Sciences, vol. 22 (LVIII) (2012).
[9] Jie Meng, Geng-yin Li, Shi-jun Cheng, Economic Dispatch for Power Generation System Incorporating Wind and Photovoltaic Power, Applied Mechanics and Materials, vol. 441, pp. 263–267 (2014).
[10] Kumar C., Anbarasan A., Karpagam M., Alwarsamy T., Artificial Intelligent Techniques in Economic Power Dispatch Problems, International Journal of Applied Engineering Research, ISSN 0973-4562, vol. 10, no. 9, pp. 23243–23254 (2015).
[11] Zeinab G. Hassan, Ezzat M., Almoataz Y. Abdelaziz, Solving Unit Commitment and Economic Load Dispatch Problems Using Modern Optimization Algorithms, International Journal of Engineering, Science and Technology, vol. 9, no. 4, pp. 10–19 (2017).
[12] Quande Q., Cheng S., Xianghua C., Solving non-convex/non-smooth economic load dispatch problems via an enhanced particle swarm optimization, Applied Soft Computing, vol. 59, no. 1, pp. 229–242 (2017).
[13] Sanjoy R., The maximum likelihood optima for an economic load dispatch in presence of demand and generation variability, Energy, vol. 147, pp. 915–923 (2018).
[14] Jagat Kishore Pattanaik, Mousumi Basu, Deba Prasad Dash, Dynamic economic dispatch: a comparative study for differential evolution, particle swarm optimization, evolutionary programming, genetic algorithm, and simulated annealing, Pattanaik et al., Journal of Electrical Systems and Information Technology (2019).
[15] Bishwajit Dey, Shyamal Krishna Roy, Biplab Bhattacharyya, Solving multi-objective economic emission dispatch of a renewable integrated microgrid using latest bio-inspired algorithms, Engineering Science and Technology, International Journal 22, pp. 55–66 (2019).
[16] Aissa Benchabira, Mounir Khiat, A hybrid method for the optimal reactive power dispatch and the control of voltages in an electrical energy network, Archives of Electrical Engineering, vol. 68, no. 3, pp. 535–551 (2019).
[17] Patel N., Bhattacharjee K., A comparative study of economic load dispatch using sine cosine algorithm, Scientia Iranica International Journal of Science and Technology, vol. 27, no. 3, pp. 1467–1480 (2020).
[18] Tankut Yalcinoz, Halis Altun, Murat Uzam, Economic dispatch solution using a genetic algorithm based on arithmetic crossover, IEEE Porto Power Tech Proceedings (2001).
[19] Anurag Gupta, Himanshu Anand, Analysis of scheduling of solar sharing for economic/environmental dispatch using PSO, INDICON IEEE (2015).
[20] Hafez A.I., Zawbaa H.M., Emary E., Hassanien A.E., Sine cosine optimization algorithm for feature selection, International Symposium on INnovations in Intelligent SysTems and Applications (INISTA) (2016).
[21] Ajay Wadhawan, Preeti Verma, Sonia Grover, Himanshu Anand, Economic Environmental Dispatch with PV Generation Including Transmission Losses using PSO, IEEE Power India International Conference (PIICON) (2016).
[22] Suid M.H., Ahmad M.A., Ismail M.R.T.R., Ghazali M.R., Irawan A., Tumari M.Z., An Improved Sine Cosine Algorithm for Solving Optimization Problems, IEEE Conference on Systems, Process and Control (ICSPC) (2018).
[23] Jiajun Liu, Bo Song,Ye Li, An Optimum Dispatching for Photovoltaic-thermal Mutual-Complementing Power Plant Based on the Improved Particle Swarm Knowledge Algorithm, IEEE Conference on Industrial Electronics and Applications (ICIEA) (2018).
[24] Kennedy J., Particle swarm optimization, Encyclopedia in Machine Learning, pp. 760–766 (2010).
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Authors and Affiliations

Abrar Mohamed Hafiz
1
ORCID: ORCID
M. Ezzat Abdelrahman
1
Hesham Temraz
1

  1. Electrical Power and Machines Department, Faculty of Engineering, Ain Shams University, Egypt
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Abstract

This paper presents the results of testing samples of shield-centering elements from medium-voltage surge arresters. The elements were made of TSE glass textolite. The elements have been dismantled from different operated surge arresters, which were subjected to discharge currents (short-circuit currents) of different intensity and duration. The discharge currents led to degradation of the tested elements with various degrees of advancement. The degradation was investigated using microscopic methods and energy-dispersive X-ray spectroscopy (EDS). Changes in the content of elements of the surface of textolite materials – as the degradation progresses – were documented.
It was found that high discharge current flows resulted in melting of the organic binder, epoxy resin, especially its surface layer. Partial charring and even burning of the resin was noticeable. Furthermore, it was found that with increasing degradation on the surface of the TSE laminate, the carbon and oxygen content, which are part of the organic resin, decreases. Simultaneously the amount of silicon, calcium and aluminium, which are present in the glass fibres, increases. The charring effect of the resin and the formation of conductive paths result in a decrease in the performance of surge arresters and their subsequent failure.
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Authors and Affiliations

P. Papliński
1
H. Śmietanka
1
P. Ranachowski
2
Z. Ranachowski
2
ORCID: ORCID
K. Wieczorek
3
S. Kudela Jr
4

  1. Institute of Power Engineering – Research Institute, 8 Mory Str., 01-330 Warsaw, Poland
  2. Institute of Fundamental Technological Research PAS, 5b Pawińskiego Str., 02-106 Warsaw, Poland
  3. Wrocław University of Science And Technology, Faculty of Electrical Engineering, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
  4. Institute of Materials and Machine Mechanics Slovak Academy of Sciences, Dúbravská Cesta 9/6319, 845 13 Bratislava, Slovakia
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Abstract

The aim of this work was to characterize the changes in microstructure and chemical composition of the austenitic overlays on a pressure vessel steel that occur in the vicinity of the interface between the overlay and the base material. The investigations were carried out on a 16Mo3 boiler pipes weld overlaid by 309 and 310 steels. The microstructural examinations were performed on longitudinal cross-sectioned samples. The qualitative and quantitative chemical composition analyses on metallographic samples were determined on Scanning Electron Microscopy (SEM) by means of Energy Dispersive Spectrometry (EDS). The article analyzes the influence of the solidification sequence in both types of steel on final microstructure.
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Authors and Affiliations

M. Rozmus-Górnikowska
1
S. Dymek
1
M. Blicharski
1
Ł. Cieniek
1
J. Kusiński
1

  1. AGH University of Science and Technology, Faculty of Metals Engineering and Industrial Computer Science, al. A. Mickiewicza 30, 30-059 Krakow, Poland
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Abstract

High temperature vacuum brazing is a well-known and commonly used method for joining of nickel based elements and subassemblies of gas turbines, both for stationary and aviation applications. Despite the fact that currently used brazing filler metals meet stringent requirements of aviation and energetic industries, a lot of effort is spent on improving operational properties of the joints through modification of chemical composition or brazing process parameters. This paper aims for both of these aspects – its purpose is evaluation of the impact of filler metal composition, brazing gap width and process conditions on the microstructure of joints between sheet metal elements made of Hastelloy X nickel superalloy. Two different Ni-based filler materials (BNi-2 and Amdry 915) were investigated, based on the results of light and scanning electron microscopy evaluations, energy dispersive X-ray spectroscopy and hardness measurements.
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Authors and Affiliations

K. Krystek
1 2
ORCID: ORCID
K. Krzanowska
1
ORCID: ORCID
M. Wierzbińska
1
ORCID: ORCID
M. Motyka
1
ORCID: ORCID

  1. Rzeszow University of Technology, Department of Materials Science, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland
  2. Pratt & Whitney Rzeszów S.A., 120 Hetmańska Str., 35-078 Rzeszów, Poland
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Abstract

The structural, morphological and photoluminescent properties of thermally evaporated neodymium oxide (Nd2O3) thin films deposited onto nanostructured silicon (Si-ns) are reported. Si-ns embedded in silicon nitride (SiN) thin films are prepared by plasma-enhanced chemical vapour deposition (PECVD). SiN and Nd2O3 thin films uniformity and Si-ns formation are confirmed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The presence of neodymium (Nd), silicon (Si), oxygen (O), and phosphorus (P) is investigated by energy-dispersive spectroscopy (EDS) and secondary ion mass spectrometry (SIMS). Post-annealing SIMS profile indicates an improvement of the homogeneity of activated P distribution in Si bulk. The X-ray diffraction (XRD) combined with Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) have been employed to determine amorphous silicon (a-Si), crystalline silicon (c-Si), Nd2O3 and SiN phases present in the Nd2O3-SiN bilayers with their corresponding chemical bonds. After annealing, a Raman shift toward lower wavenumbers is recorded for the Si peak. XPS data reveal the formation of Nd2O3 thin films with Nd-O bonding incorporating trivalent Nd ions (Nd3+). Strong room-temperature photoluminescence is recorded in the visible light range from the Si-ns. Nd-related photoluminescent emission in the near infrared (NIR) range is observed at wavelengths of 1025–1031 nm and 1083 nm, and hence is expected to improve light harvesting of Si-based photovoltaic devices.
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Authors and Affiliations

Amine Mefoued
1 2
ORCID: ORCID
Bedra Mahmoudi
1
Nasser Benrekaa
2
Faiza Tiour
1
Hamid Menari
1
Abdelyamine Naitbouda
3
Amar Manseri
1
Afaf Brik
1
Salah Mezghiche
1
Moustafa Debbab
4

  1. Centre de Recherche en Technologie des Semi-conducteurs pour l’Énergétique (CRTSE), 02 Bd Frantz Fanon BP140, Alger–7 merveilles, 16027 Algiers, Algeria
  2. Faculté de Physique, Université des Sciences et de la Technologie Houari Boumediene (USTHB), BP 32 Bab-Ezzouar, 16111 Algiers, Algeria
  3. Centre de Développement des Technologies Avancées (CDTA), Cité 20 août 1956, 16081 Algiers, Algeria
  4. Université Abou Bekr Belkaid BP 230, 13000 Chetouane, Tlemcen, Algeria
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Abstract

The Electronic System «Archival Card Index» (АСI) represents the digital format of lexical and illustrative materials of the Commission of the Dictionary Living Ukrainian language (All-Ukrainian Academy of Sciences), which created the «Russian-Ukrainian Dictionary» by ed. A. Krymsky and S. Yefremov, today recognized as the superlative of Ukrainian lexicography of the 20-30’s of the 20th century, and which is becoming even more relevant today. The value of the АСI consists in the fact that it contains materials IV volume of the «Russian-Ukrainian Dictionary» destroyed in 1933. For the first time since the 1930’s ACI became the object of scientific attention precisely as materials of the repressed Commission, for more than half a century they were considered lost. ACI digital format is needed in order to prevent its physical decay, to return to the linguistic-cultural process, to optimize research work. After all, ACI contains professionally processed linguistic sources of general dictionaries first half XXth century, which are of great value for the restoration of the authenticity of Ukrainian language thinking, to eliminate the prolonged russification of Ukrainian vocabulary and the creation of dictionaries of the Ukrainian language of the 21th century.

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Authors and Affiliations

Оксана М. Тищенко

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