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Abstract

This study discusses the synthesis, characterization and development of self-healing nanocomposite of amino-terminated PDMS (Polydimethylsiloxane), Epoxy (EPON828¸ Diethylenetriamine (DETA)), and Graphene Oxide (GO).GOwas prepared using a modified Hummer’s method andwas incorporated into the PDMS-Epoxy composite in various ratios (0.1 wt.%, 0.3 wt.%, and 0.5 wt.%) using toluene as the dispersing medium. Fourier TransformInfrared Spectroscopy was used for confirming the presence of the designed/prepared structures, and thermo-mechanical analysis was performed to test the change in glass transition temperature and initiation temperature of self-healing process. The composite resins were coated on mild steel substrates by curing freshly prepared resins over the substrates at elevated temperatures. The corrosion behavior of mild steel in 3.5 wt.% NaCl solution before and after the coatings was studied using Tafel Electrochemical Polarization test. The self-healing properties of the materials were also studied by applying cuts on the material and letting them heal under elevated temperatures, and the results showed that the prepared coating demonstrated an effective corrosion resistance for mild steel for various marine applications.
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Authors and Affiliations

Krishna Moorthi
1 2
Vishesh Saxena
1 3
R.V. Siva Prasanna Sanka
4
Sravendra Rana
1

  1. University of Petroleum & Energy Studies (UPES), School of Engineering, Energy Acres, Bidholi, Dehradun, 248007, India
  2. Georgia Institute of Technology, Atlanta, GA, 30332, USA
  3. Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen AG 9747, The Netherlands
  4. Department of Mechanical Engineering, University Institute of Engineering, Chandigarh University, Mohali, India
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Abstract

High tin bronze alloy (Cu>17wt.%Sn) is commonly as raw material to fabricate musical instruments. Gamelan musical instruments in Indonesia are produced using tin bronze alloy raw materials. The tin bronze alloy used by each gamelan craftsman has a different tin composition, generally in the range of Cu(20-24) wt.% Sn. This study aims to investigate the effect of microstructure, density, and mechanical properties of Cu(20-24)wt.%Sn against the acoustic properties processed by the sand casting method. The material is melted in a crucible furnace until it reaches a pouring temperature of 1100ºC by the sand casting method. The specimens were subjected to microstructure observations, density and porosity as well as mechanical properties testing including tensile strength, bending strength, hardness, and modulus of elasticity. Mechanical properties data then used to calculate several parameters of acoustic properties including speed of sound (c), impedance (z) and radiation coefficient (R). Processes simulation using Finite Element Analysis (FEA) and Experiment Method Analysis (EMA) were carried out to determine acoustic properties including sound intensity, natural frequency and damping capacity.
The experimental result shows that the increase in tin composition in Cu(20-24) wt.% Sn changed the microstructure of coarse grains into dendrite-columned fine grains. Physical properties of density decrease, while porosity increases. Mechanical properties including tensile strength, modulus of elasticity, and bending strength decreased, while the hardness of the alloy increases. The calculation of acoustic parameters such as the speed of sound (c), impedance (z) and radiation coefficient (R) has decreased. Moreover, sound intensity (dB), natural frequency (Hz) and damping capacity also decrease with increasing tin composition. Hence, tin bronze alloy Cu20wt.%Sn is the recommended raw material for the manufacture of gamelan instruments through the sand casting method.
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Bibliography

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[2] Sutton, R.A. (2007). Gamelan: The Traditional Sounds of Indonesia (review). Asian Music. 38(1), 142-144.
[3] Suyanto, Tjokronegoro H.A, Merthayasa I.G.N. & Supanggah R. (2015). Acoustic parameter for javanese gamelan performance in pendopo mangkunegaran Surakarta. Procedia – Social and Behavioral Sciences. 184. 322-327.
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[8] Sugita, I.K.G. Soekrisno, R. & Miasa, I.M. (2011). The effect of annealing temperature on damping capacity of the bronze 20 % Sn alloy. International Journal of Mechanical & Mechatronics Engineering. IJMME-IJENS. 11(4).1-5.
[9] Slamet, S. Suyitno, & Kusumaningtyas, I. (2019). Effect of composition and pouring temperature of Cu (20-24) wt.% Sn by sand casting on fluidity and Mechanical Properties, Journal of Mechanical Engineering and Science. 13(4). 6022-6035.
[10] Sugita, I.K.G. & Miasa, I.M. (2013). Feasibility Study On The Use Of Silicon-Bronze Alloys As An Alternative Material For Balinese Musical Instruments. 20th International Congress on Sound & Vibration; 7-11 July 2013.1-5. Bangkok, Thailand
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Authors and Affiliations

S. Slamet
1 2
S. Suyitnoa
1
I. Kusumaningtyasa
1
I.M. Miasaa
1

  1. Universitas Gadjah Mada, Yogyakarta, Indonesia
  2. Universitas Muria Kudus, Kudus, Indonesia
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Abstract

The Vistulian decline was a period of rapid environmental events. The authors correlated ages of the last Scandinavian Ice Sheet limits in northern Poland with ages of prominent events adapting the conditions of periglacial environment of Central Poland in response to the Late Vistulian climate warming. Ages from previous thematic geological and palaeogeographical studies were collected. The approach used indicates that despite methodological uncertainties and sometimes inconsistency of ages, it is especially helpful in timing of first warming signals (ca. 19–18 cal ka BP) and establishing of environmentally bipartite 3 millennia of the Oldest Dryas in the extraglacial zone. Abrupt warming at the onset of the Bølling-Allerød is well registered in biotic and abiotic archives available from Central Poland and remains in agreement with the large recession of the southern ice sheet margin.

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Authors and Affiliations

Danuta A. Dzieduszyńska
Jacek Forysiak
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Abstract

The aim of the paper is to present a procedure for generating service loading for fatigue tests of materials and structures. The generated loading characterizes desired functions of probability distribution and autocorrelation. The proposed numerical procedure uses MATLAB toolboxes and consists of three steps: (a) generation of a sequence of real numbers with the desired autocorrelation function and with any probability distribution function; (b) generation of loading history with the desired probability distribution function; (c) rearrangement of loading history (mentioned in item b) based on a sequence of real numbers with the desired correlation (mentioned in item a).

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Authors and Affiliations

Ewald Macha
Roland Pawliczek
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Abstract

Podwaliny [Foundations], the poem written by Leopold Staff right after the war and carrying traces of a profound trauma, takes advantage of the motifs drawn from the biblical parable of good and bad construction practices (Gospel According to St Matthew, 7:24–27). In her interpretation of the poem, the author analyses the way(s) in which the biblical paradigm has been transformed, and the consequences of this procedure. Use is made of the opinions of the scholars who have reconstructed the primary function of parabolic stories, having identified in them the original forms of thinking which preceded the evolvement of abstract concepts encoding qualities.

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Authors and Affiliations

Teresa Dobrzyńska

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