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Number of results: 11
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Abstract

The aim of the study was to develop an assessment methodology for the temperature of the surface of the friction pair during the braking for mine hoists. During the braking process, the work of friction is transformed into heat at the level of friction surfaces, and in case high temperatures are reached, the friction coefficient is influenced negatively, thus the risk of braking failure exists. In the first part of the study we measured the temperature of the friction surfaces for a particular case of hoist in real braking conditions. In the second part of the study is presented a theoretical model for the calculation of the temperatures resulted in the braking process for the hoist equipped with shoe brakes. The theoretical model for calculation was simulated numerically for a particular case in real braking conditions. Based on the conclusions resulted after the study, a series of hypotheses and recommendations for adjusting the control of the process parameters have been given out, in order to avoid the excessive heating of the brakes of the hoists and, respectively, their improved safety, maintenance and availability.

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Authors and Affiliations

Miorita Ungureanu
Nicolae Stelian Ungureanu
Marius Cosma
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Abstract

Use ofvarious wastes containing iron or aluminium in wastewater treatment can be considered as an alternative method to expensive and commercial reagents. These wastes can be recycled thanks to this method, which is important from an environmental point of view. Washings generated during ground water treatment arc rather useless but they are one of waste iron sources. The article demonstrates a description of two ground water treatment plants supplying the city of Koszalin with drinking water. On the basis ofdata from the last four years, a balance of the annual amount of iron sludge formed as a result of backwashing filter beds in both plants was performed. The amount of waste iron exceeds 10 Mg Fe-year. Research on waste iron usage to remove orthophosphates from a model solution and real sludge liquor from sludge digestion showed that iron sludge from washings can be efficiently used in wastewater treatment technology.
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Authors and Affiliations

Krzysztof Piaskowski
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Abstract

Groundwater is a vital resource for domestic, agricultural, industrial activities and ecosystem services. Despite its multi-ple purposes, the resource is under significant threat owing to increasing contamination from anthropogenic activities and climate change. Hence, in order to ensure the reliability and sustainable use of groundwater for the present and future gener-ations, effective management of groundwater (quality and quantity) is highly important. This can be achieved by identifying areas more vulnerable to contamination and implementing protective measures. The present study aims at assessing the vul-nerability of groundwater using GIS-based DRASTIC index in the Quaternary catchment (A21C) within Limpopo River Basin. The vulnerability index varied from 87 to 207. About 53.6% (408 km2) of the catchment area also exhibited high risk of groundwater contamination mostly in central, north-eastern and western part of the sub-catchment. The medium and low vulnerability classes cover only 18.1% (137.5 km2) and 21.7% (165.1 km2) of the study area, respectively. The shallow groundwater at the Doornfontein Campus belongs to very high vulnerability area. The sensitivity analysis indicates that depth to water level, recharge, aquifer media, soil and topography are the important contributors to vulnerability assessment. The correlation analysis performed to validate the final vulnerability map shows a moderate positive correlation, indicating the model’s applicability to the urbanised environment. The study indicates an area that is highly vulnerable to pollution, and hence protective measures are necessary for sustainable management of the groundwater resource in the study area. The result of this study can also be further improved and verified by using other vulnerability assessment models.
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Authors and Affiliations

Simeneh S. Moges
1
ORCID: ORCID
Megersa O. Dinka
1
ORCID: ORCID

  1. University of Johannesburg, Faculty of Engineering and the Built Environment, Department of Civil Engineering Sciences, PO Box 524, Auckland Park, 2006 Johannesburg, South Africa
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Abstract

Computational Materials Engineering (CME) is a high technological approach used to design and develop new materials including the physical, thermal and mechanical properties by combining materials models at multiple techniques. With the recent advances in technology, the importance of microstructural design in CME environments and the contribution that such an approach can make in the estimation of material properties in simulations are frequently discussed in scientific, academic, and industrial platforms. Determination of the raw material characteristics that can be modeled in a virtual environment at an atomic scale by means of simulation programs plays a big role in combining experimental and virtual worlds and creating digital twins of the production chain and the products. In this study, a new generation, alternative and effective approach that could be used to the development of Al-Si based wheel casting alloys is proposed. This approach is based on the procedure of optimizing the physical and thermodynamic alloy properties developed in a computer environment with the CME technique before the casting phase. This article demonstrates the applicability of this approach in alloy development studies to produce Al-Si alloy wheels using the low pressure die casting (LPDC) method. With this study, an alternative and economical way is presented to the alloy development studies by trial and error in the aluminum casting industry. In other respects, since the study is directly related to the automotive industry, the reduction in fuel consumption in vehicles is an expected effect, as the new alloy aims to reduce the weight of the wheels. In addition to conserving energy, reducing carbon emissions also highlights the environmental aspects of this study.
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Bibliography

[1] Cullen, J.M. & Allwood, J.M. (2013). Mapping the global flow of aluminum: from liquid aluminum to end-use goods. Environmental Science & Technology. 47(7), 3057-3064. DOI: 10.1021/es304256s.
[2] Liu, G. & Müller, D.B. (2012). Addressing sustainability in the aluminum industry: a critical review of life cycle assessments. Journal of Cleaner Production. 35, 108-117. DOI: 10.1016/j.jclepro.2012.05.030.
[3] Ashkenazi, D. (2019). How aluminum changed the world: A metallurgical revolution through technological and cultural perspectives. Technological Forecasting and Social Change. 143, 101-113. DOI: 10.1016/j.techfore.2019.03.011.
[4] Musfirah, A.H. & Jaharah, A.G. (2012). Magnesium and aluminum alloys in automotive industry. Journal of Applied Sciences Research. 8(9): 4865-4875.
[5] Davies, J.R. (1993). Aluminum and Aluminum Alloys. ASM International, OH.
[6] Mondolfo, L.F. (1976). Aluminum alloys: Structure and Properties. London, Butterworths.
[7] Rana, R.S., Purohit, R. & Das S. (2012). Reviews on the influences of alloying elements on the microstructure and mechanical properties of aluminum alloys and aluminum alloy composites. International Journal of Scientific and Research Publications. 2(6).
[8] Heusler, L. & Schneider, W. (2002). Influence of alloying elements on the thermal analysis results of Al–Si cast alloys. Journal of Light Metals. 2(1), 17-26. DOI: 10.1016/s1471-5317(02)00009-3.
[9] Miller, W., Zhuang, L., Bottema, J., Wittebrood, A., De Smet, P., Haszler, A. & Vieregge, A. (2000). Recent development in aluminium alloys for the automotive industry. Materials Science and Engineering: A. 280(1), 37-49. DOI: 10.1016/s0921-5093(99)00653-x.
[10] Krol, M., Tanski, T., Snopinski, P. & Tomiczek, B. (2017). Structure and properties of aluminium–magnesium casting alloys after heat treatment. Journal of Thermal Analysis and Calorimetry. 127, 299-308.
[11] Callister, W.D. (1997). Materials science and engineering: An introduction. New York: John Wiley & Sons.
[12] Allison J., Backman D. & Christodoulou L. (2006). Integrated computational materials engineering: A new paradigm for the global materials profession. JOM. 58, 25-27.
[13] Allison, J., Li M., Wolverton, C. & Su, X.M. (2006). Virtual aluminum castings: an industrial application of ICME. JOM. 58, 28-35.
[14] Schmid-Fetzer, R. & Gröbner, J. (2001). Focused development of magnesium alloys using the CALPHAD approach. Advanced Engineering Materials. 3(12), 947-961. DOI: 10.1002/1527-2648(200112)3:1.
[15] Jung, J.-G., Cho, Y.-H., Lee, J.-M., Kim, H.-W. & Euh, K. (2019). Designing the composition and processing route of aluminum alloys using CALPHAD: Case studies. CALPHAD. 64, 236-247. DOI: 10.1016/j.calphad.2018.12.010.
[16] Jha, R. & Dulikravich, G.S. (2020). Solidification and heat treatment simulation for aluminum alloys with scandium addition through CALPHAD approach. Computational Materials Science. 182, 109749. DOI: 10.1016/j.commatsci.2020.109749.
[17] Assadiki A., Esin V.A., Bruno, M. & Martinez, R. (2018). Stabilizing effect of alloying elements on metastable phases in cast aluminum alloys by CALPHAD calculations. Computational Materials Science. 145, 1-7. DOI: 10.1016/j.commatsci.2017.12.056.
[18] Jiao, X.Y., Liu, C.F., Guo, Z.P., Tong, G.D., Ma, S.L., Bi, Y. et al. (2020). The characterization of Fe-rich phases in a high-pressure die cast hypoeutectic aluminum-silicon alloy. Journal of Materials Science & Technology. 51, 54-62. DOI: 10.1016/j.jmst.2020.02.040.
[19] Pehlivanoglu, U., Yağcı, T. & Çulha, O. (2021). Effects of air-cooling-hole geometries on a low-pressure die-casting process. Materials and Technology. 55(4), 549-558. DOI: 10.17222/mit.2021.043
[20] Lumley, R. (2011). Fundamentals of Aluminium Metallurgy. Wood Publishing Limited, Oxford, Cambridge, Philadelphia, New Delhi.
[21] Snugovsky, L., Major, J.F., Perovic, D.D. & Rutter, J.W. (2000). Silicon segregation in aluminium casting alloy. Materials Science and Technology. 16(2), 125-128. DOI: 10.1179/026708300101507604.
[22] Ebhota, W.S. & Jen, T.C. (2017). Effects of modification techniques on mechanical properties of Al-Si cast alloys. In Subbarayan Sivasankaran (Eds.), Aluminium Alloys - Recent Trends in Processing, Characterization, Mechanical Behavior and Applications. London, UK: IntechOpen. DOI: 10.5772/intechopen.70391
[23] Jiang, W., Yu, W., Li, J., You, Z., Li, C. & Lv, X. (2018). Segregation and morphological evolution of Si phase during electromagnetic directional solidification of hypereutectic Al-Si alloys. Materials. 12(1), 10. DOI: 10.3390/ma12010010
[24] Yıldırım, M. & Özyürek, D. (2013). The effects of Mg amount on the microstructure and mechanical properties of Al–Si–Mg alloys. Materials and Design. 51, 767-774. DOI: 10.1016/j.matdes.2013.04.089.
[25] Kumar V., Mehdi, H., Kumar A. (2015). Effect of silicon content on the mechanical properties of aluminum alloy. International Research Journal of Engineering and Technology. 2(4), 1326-1330.
[26] Li, W., Cui, S., Han, J. & Xu, C. (2006). Effect of silicon on the casting properties of Al-5.0% Cu alloy. Rare Metals. 25, 133-135. DOI: 10.1016/s1001-0521(08)60067-4
[27] Yang, Y.S. & Tsao, C.Y.A. (1997). Viscosity and structure variations of Al-Si alloy in the semi-solid state. Journal of Materials Science, 32(8), 2087-2092. DOI: 10.1023/A:1018522805543.
[28] Campbell, J. (2003). Castings: the new metallurgy of cast metals. 2nd Edition, Elsevier Butterworth-Heinemann, Oxford.
[29] Atasoy, Ö.A. (1990). Ötektik Alaşımlar: Katılaşma Mekanizmaları ve Uygulamaları. İstanbul Technical University, İstanbul.
[30] Sahoo, M. & Sahu, S. (2014). Principles of metal casting. 3rd Edition, McGraw-Hill Education.
[31] Clemex, Dendrite Arm Spacing in Aluminum Alloy Report. Retrieved August 24, 2021, from https://clemex.com/analysis/dentritic-arm-spacing/
[32] Peres, M.D., Siqueira, C.A. & Garcia, A. (2004). Macrostructural and microstructural development in Al-Si alloys directionally solidified under unsteady-state conditions. Journal of Alloys and Compounds. 381(1-2), 168-181. DOI: 10.1016/j.jallcom.2004.03.107.
[33] Spear, R.E. & Gardner, G.R. (1963). Dendrite cell size. AFS Transactions. 71, 209-215. [34] Rhadhakrishna, K, Seshan, S. & Seshadri, M.R. (1980). Dendrite arm spacing in aluminium alloy castings, AFS Transactions. 88, 695-702.
[35] Flemings, M. Kattamis, T.Z. & Bardes, B.P. (1991). Dendrite arm spacing in aluminium alloys. AFS Transactions. 99, 501-506.
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Authors and Affiliations

T. Yağcı
1
Ü. Cöcen
1
O. Çulha
2

  1. Dokuz Eylul University, Dept. of Metallurgical and Materials Engineering, İzmir, Turkey
  2. Manisa Celal Bayar University, Dept. of Metallurgical and Materials Engineering, Manisa, Turkey
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Abstract

In 1822 and 1838 two finds of late Roman solidi hoarded around AD 430/440 were unearthed at the Goldberg near Klein Tromp in former Eastern Prussia (now Trąbki Małe, Poland). With an approximate total of 141 gold coins confi rmed (including one aureus of Gordian III) this hoard represents the largest hoard of Roman solidi in Poland and the Baltic region to date. Most of the coins entered the Royal Cabinet in Berlin, while smaller parts were given to the University at Königsberg and the landowner. This article provides an overview of the history of the hoard’s discovery and later fate.

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Authors and Affiliations

Karsten Dahmen
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Abstract

This study gives an analysis of the variation of main meteorological parameters on the Station Arctowski in the time from December 1979 through March 1980 — the summer season of the IV Antarctic Expedition of the Polish Academy of Sciences. Characteristics of wind speed and direction, of air temperature, atmospheric pressure, precipitation, cloudiness, soil temperature at the station and surface water temperatures of the Admiralty Bay are based on the standard synoptic observations.

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Authors and Affiliations

Barbara Cygan
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Abstract

This article aims to reconstruct Max Scheler’s conception of three types of knowledge, outlined in his late work Philosophical Perspectives (1928). Scheler distinguished three kinds of knowledge: empirical, used to exercise control over nature, eidetic (essential) and metaphysical. I review the epistemological criteria that underlie this distinction, and its functionalistic assumptions. In the article’s polemic part I accuse Scheler of a) crypto-dualism in his theory of knowledge, which draws insufficient distinctions between metaphysical and eidetic knowledge; b) totally omitting the status of the humanities in his classification of knowledge types; c) consistently developing a philosophy of knowledge without resort to the research tools offered by the philosophy of science, which takes such analyses out of their social and historical context (i.e., how knowledge is created in today’s scientific communities).

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Authors and Affiliations

Stanisław Czerniak
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Abstract

The article includes considerations and author’s proposals concerning the regional dimension of social policy. This aspect of social policy has not been investigated widely so far. The scope of regionalism and its forms are linked with the dominant social doctrine in a given country. They reflected in the ratio of territorial self-governments’ own incomes against those of the state budget, and in the institutional freedom they have in the area of benefit structuring, that is in decentralization. In the case of Poland, the political changes connected with the doctrinal ones hamper the development of regional social policy. This may have a negative impact on the coordination and implementation of social policy actions undertaken on different government levels and on the adjustment of social benefits to the needs of a region’s residents.

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Authors and Affiliations

Józef Orczyk
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Abstract

This paper deals with the experimental validation of the suitability of the method for measuring radial variations of components on the process tool. The tests were conducted using a computerized PSA6, which was compared to a Talyrond 73. The results of measurement of roundness deviations as well as roundness profiles were analyzed for a sample of 70 shafts. The roundness deviations were assessed by determining the experimental errors, while the profiles obtained with the tested device were compared to those registered by the reference device using three correlation coefficients.

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Authors and Affiliations

Krzysztof Stępień
Włodzimierz Makieła
Stanisław Adamczak
Adam Janusiewicz
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Abstract

The paper presents an analysis of the influence of elevated temperature on thin-walled purlins restrained by sheeting. In the first part of the study the bearing capacity of purlins cooperating with sheeting is examined in normal and elevated temperature based on European Standards. Next, special attention is paid to creating a numerical FEM model of the restrained purlins in Abaqus program taking into account different materials properties with respect to temperature increase.

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Authors and Affiliations

K. Rzeszut
Ł. Polus
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Abstract

Article published in Science, 2012 by Jennifer A. Doudna, Emmanuelle Charpentier and their team presented a novel tool named as CRISPR/Cas9. The original CRISPR/Cas9 tool and the whole system developed from it since then allow making precise changes in the nucleotide sequence in the defined locus of the genome. The article presents the already known as well the potential future applications of the system for improvement of cultivated plants. The separate section is devoted to present the background of the Court of Justice decision C-528/16. Discussed are the far reaching negative consequences of this, based not on the merit decision, for the future of European green biotechnology.

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Authors and Affiliations

Wacław Orczyk

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