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Number of results: 130
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Abstract

The literature investigates the relation between savings and interest rate mainly for household sector, but in recent decades households ceased to be the main source of savings in the economy. We try to identify how the savings of different sectors respond to the interest rate change using the SVAR methodology. We focus on Poland and generalize the results for other European economies. We find that although the household savings rate tends to rise after an increase of interest rate, the corporate savings simultaneously fall, inducing a negative conditional correlation between them. The responses of savings rate of general government and foreign savings are diverse (although the former usually declines after an interest rate increase) and does not seem to be related to factors like the membership in the currency union or the level of public debt. We also check the existence of the ‘crowding-out’ effects and conclude it only applies in the case of government savings crowding out household savings.

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Authors and Affiliations

Michał Gradzewicz
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Abstract

This study examines whether the lowering interest-rate environment in CEE countries since the early 2000’s increased bank risk-taking behaviour. We employ 6,979 annual observations from the Bankscope database over the period 1997‒2011 and find a positive relationship between bank risk-taking, measured by risk assets, and interest rates. On the contrary, there is a negative relationsh ipbetween non-performing loans and interest rates. These results are robust across a number of different specifications that account,inter alia, for the potential endogeneity of interest rates and/or the dynamics of bank risk. Moreover, we provide evidence that these findings are mainly driven by the banking sector of the Russian Federation rather than that of the rest CEE countries.

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Authors and Affiliations

Georgios P. Kouretas
Chris Tsoumas
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Abstract

The swap spread is defined as the difference between the fixed rate of an interest rate swap and the yield of the treasury with the same maturity. The swap spread is usually interpreted as the effective proxy of bank liquidity and the credit spread indicator. The interpretation is very similar to the LIBOR-OIS spread and in the context of Polish interbank market – WIBOR-OIS. However, WIBOR-OIS is less reliable during the crisis of confidence because of lack of interbank operation with the maturity longer than 1 month. Swap spreads base on two liquid instruments, thus they are free of this defect.

The main goal of this paper is to assess how Polish swap spreads and their conditional variance reacted to important events connected with the subprime crisis and crisis of confidence in the Polish interbank market.

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Authors and Affiliations

Piotr Płuciennik
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Abstract

Forecasting yield curves with regime switches is important in academia and financial industry. As the number of interest rate maturities increases, it poses difficulties in estimating parameters due to the curse of dimensionality. To deal with such a feature, factor models have been developed. However, the existing approaches are restrictive and largely based on the stationarity assumption of the factors. This inaccuracy creates non-ignorable financial risks, especially when the market is volatile. In this paper, a new methodology is proposed to adaptively forecast yield curves. Specifically, functional principal component analysis (FPCA) is used to extract factors capable of representing the features of yield curves. The local AR(1) model with time-dependent parameters is used to forecast each factor. Simulation and empirical studies reveal the superiority of this method over its natural competitor, the dynamic Nelson-Siegel (DNS) model. For the yield curves of the U.S. and China, the adaptive method provides more accurate 6- and 12-month ahead forecasts.

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Authors and Affiliations

Ying Chen
Bo Li
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Abstract

Changes in the size and the age structure of a population have a great impact on an economy, especially on national savings and capital flows. Poland’s population, although still relatively young when compared to other developed countries, is expected to experience accelerated ageing and decline in forthcoming decades. In this paper, we assess the effects of these processes for Polish economy. Using an open-economy OLG model with demographic shocks and a variable retirement age, we simulate dynamics of real interest rates, main macro aggregates as well as net foreign assets to GDP. We show that rapid ageing will reduce the interest rate gap between Poland and the developed countries by 1.3-2 p.p. We also document a strong positive relationship between interest rates and the retirement age and find that the decline in the interest rate in Poland is primarily driven by the surviving probability shock

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Authors and Affiliations

Jan Acedański
Julia Włodarczyk
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Abstract

This study attempts to evaluate the field performance of various mining equipment used at the development galleries of coal mines. These are hand-held and jumbo rock drills, and a roadheader used in mechanical excavation. For this purpose, the penetration rates of rock drills were monitored and measured in the field. The physical, mechanical, and drillability properties were determined through the collected samples in order to understand the complex interactions between the rock and bit/pick. The abrasive mineral content was also analyzed with XRD analysis to examine the wear on the cutting/drilling tools. Besides, the specific energy of the equipment was calculated relying on the operational parameters. A comparison of the monthly advance and production rates of the drilling rigs and roadheader was made. The relations among operating power, specific energy, and design of buttons/picks were investigated. It has been found that the average advance and production rates of the mining equipment are consistent with the penetration rate. The results verified that the roadheader used in mechanical excavation and the jumbo drill used in drilling and blasting technique are the machines maximizing the advance and production rates.

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Authors and Affiliations

Okan Su
ORCID: ORCID
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Abstract

Between 2014 and 2016 the number of foreigners on the Polish labour market increased by over 300 per cent. They were mainly Ukrainian citizens taking up seasonal employment on the basis of the so-called ‘sim-plified system’. According to the literature, such a large increase in labour immigration in a short period of time may be an important factor in the growth of unemployment and the reduction of the employment rate of natives. The main purpose of this text is to show the correlation between the increase in the employment of foreigners in Poland and to determine whether or not this has had an impact on the deterioration of the state of the labour market. For this purpose, data from the Central Statistical Office and the Polish Ministry of Family, Labour and Social Policy were collected. As a result of our analysis, it was found that the significant increase in the presence of foreigners on the Polish labour market, which the country has faced in recent years, was not correlated with the rise in unemployment, the increase in the rate of economic inactivity and the availability of seasonal jobs. On this basis, we can state that the increase in the supply of foreigners on the Polish labour market, compared to other factors influencing it, was weak enough for the negative effects of the increased employment of foreigners to not occur.

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Authors and Affiliations

Maciej Duszczyk
Kamil Matuszczyk
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Abstract

Rain gardens are one of the best measures for rainfall runoff and pollutant abatement in sponge city construction. The rain garden system was designed and developed for the problem of severely impeded urban water circulation. The rain gardens monitored the rainfall runoff abatement and pollutant removal capacity for 46 sessions from January 2018 to December 2019. Based on these data, the impact of rain gardens on runoff abatement rate and pollutant removal rate was studied. The results obtained indicated that the rain garden on the runoff abatement rate reached 82.5%, except with extreme rainfall, all fields of rainfall can be effectively abated. The removal rate of suspended solid particles was the highest, followed by total nitrogen and total phosphorus, the total removal rate in 66.35% above. The rain garden is still in the “youth stage”, and all aspects of the operation effect are good.
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Bibliography

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Authors and Affiliations

Weijia Liu
1
Qingbao Pei
2
Wenbiao Dong
2
Pengfan Chen
2

  1. East China University of Technology, Nanchang, China
  2. Nanchang Institute of Technology Poyang Lake Basin Water Engineering Safety and Efficient Utilization National and Local Joint Engineering Laboratory, Nanchang, China
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Abstract

The polycyclic musk fragrances AHTN (Tonalide) and HHCB (Galaxolide) are the most common components of cosmetics and detergents. Use of AHTN and HHCB per year (in the USA and in EU) was estimated at 1500 Mg and 3800 Mg, respectively. Because of their persistent character, musk compounds are introduced into environment mostly via urban sewage treatment plant effluents. The aim of the presented research was to assess the receptivity of AHTN and HHCB to the oxidation by means of UV-radiation and in the UV /H2O2 process. The investigations were performed in the treated wastewater and the drinking water. After 8 minutes, in all experiments performed on drinking water, the degradations of AHTN and HHCB in the range of 99% were observed. The removal of HHCB from wastewater by means of UV radiation exceeded up 93% (after 8 minutes of the process), whereas the disappearance degree of this compound in wastewater, after only 3 minutes ofUV/H2O2 process, exceeded 99%. The degradation constant rate for AHTN in drinking water using UV radiation was equal to 0.764 rnin' when the degradation rate ofHHCB was estimated at 0.634 min'. In the wastewater, the coefficient rate ofHHCB degradation by means ofUV/H2O2 was nearly 4.5 times higher (1.580 min') in comparison to the value obtained by direct photolysis of HHCB (0.354 min').
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Authors and Affiliations

Ewa Felis
Alfredo C. Alder
Joanna Surmacz-Górska
Korneliusz Miksch
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Abstract

The symbolic analysis of heart rate variability (biomarker of cardiac autonomic homeostasis) is a nonlinear and effective tool for pattern extraction and classification in a series analysis, which implies the transformation of an original time series into symbols, represented by numbers. Autonomic heart rate control is influenced by different factors, and better indicators of heart rate variability are found in healthy young individuals than in older and sicker individuals. The aim of this study was to compare the indicators of heart rate variability among healthy dogs in different age groups and in health status using the nonlinear method of symbolic analysis to evaluate the diagnostic accuracy of this method for the risk of death in dogs. An increase in cardiac sympathetic modulation was observed in puppies and dogs at risk of death, which was evidenced by a marked increase of 0 V% (without variation – associated with sympathetic modulation) and a decrease in patterns of 2 V% (two variations – associated with parasympathetic modulation), while the opposite was observed in young adult dogs with increased parasympathetic modulation. Elderly dogs showed a gradual decrease in parasympathetic activity, which tended to worsen with loss of health. It is concluded that the variables of symbolic analysis may be useful to evaluate autonomic modulation in dogs and assist in the differentiation between health states, advanced disease and death throughout the life cycle and have been shown to be indices with high specificity, sensitivity and diagnostic accuracy to help identify dogs at risk of death.
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Bibliography

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Authors and Affiliations

L. Martinello
1
F.G. Romão
1
M.F. Godoy
2
L.H.A. Machado
1
M.H. Tsunemi
3
M.L.G. Lourenço
1

  1. São Paulo State University (Unesp), School of Veterinary Medicine and Animal Science
  2. Department of Cardiology and Cardiovascular Surgery – São José do Rio Preto Medical School (FAMERP)
  3. São Paulo State University (Unesp), Institute of Biosciences, Botucatu, São Paulo, Brazil
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Abstract

Wireless sensor network (WSN) is assortment of sensor nodes proficient in environmental information sensing, refining it and transmitting it to base station in sovereign manner. The minute sensors communicate themselves to sense and monitor the environment. The main challenges are limited power, short communication range, low bandwidth and limited processing. The power source of these sensor nodes are the main hurdle in design of energy efficient network. The main objective of the proposed clustering and data transmission algorithm is to augment network performance by using swarm intelligence approach. This technique is based on K-mean based clustering, data rate optimization using firefly optimization algorithm and Ant colony optimization based data forwarding. The KFOA is divided in three parts: (1) Clustering of sensor nodes using K-mean technique and (2) data rate optimization for controlling congestion and (3) using shortest path for data transmission based on Ant colony optimization (ACO) technique. The performance is analyzed based on two scenarios as with rate optimization and without rate optimization. The first scenario consists of two operations as kmean clustering and ACO based routing. The second scenario consists of three operations as mentioned in KFOA. The performance is evaluated in terms of throughput, packet delivery ratio, energy dissipation and residual energy analysis. The simulation results show improvement in performance by using with rate optimization technique.
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Authors and Affiliations

Savita Sandeep Jadhav
1
Sangeeta Jadhav
2

  1. Dr. D.Y. Patil Institute of Technology, Pimpri, Pune, India
  2. Army Institute of Technology, Dighi Hills, Pune, India
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Abstract

The Fe-based alloy with manganese led to the appearance of new austenitic alloys, with the antiferromagnetic property pursued, resulting in compatibility with the magnetic field as that of magnetic resonance imaging. The corrosion resistance behavior of the biodegradable Fe-Mn-Si alloy was analyzed in a thermostatic chamber at 37±1°C for 24, 48 and 72 hours by immersing in Ringer solution. Also, the cast and laminated samples were subjected to electro-corrosion tests using a potentiostat equipment. Linear and cyclic potentiometry is presented for characterize the corrosion behavior of the experimental samples in electrolyte. Due to the interaction between the alloy and the liquid medium a change in the solution pH was observed. Structure analysis and chemical composition details of the surfaces were obtained using electron scanning microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS).
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Authors and Affiliations

A.-M. Roman
1
ORCID: ORCID
R. Chelariu
1
ORCID: ORCID
R. Cimpoesu
1
ORCID: ORCID
I. Stirbu
1
ORCID: ORCID
I. Ionita
1
ORCID: ORCID
M.M. Cazacu
2
ORCID: ORCID
B.A. Prisecariu
3
ORCID: ORCID
N. Cimpoesu
3
ORCID: ORCID
P. Pietrusiewicz
4
ORCID: ORCID
A. Sodor
3
ORCID: ORCID

  1. Faculty of Materials Science and Engineering, “Gheorghe Asachi” Technical University of Iasi, 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. “Grigore T. Popa” University of Medicine and Pharmacy of Iasi, 16 Univ. Street, 700115 Iasi, Romania
  4. Częstochowa University of Technology, Department of Physics , 42-200 Częstochowa, Poland
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Abstract

Luminescence dating is based mainly on the dosimetric properties of quartz and feldspar. These minerals are among the most popular found on Earth, resulting in the possibility of using luminescence methods in practically any environment. Currently, quartz remains the best recognized mineral in terms of dosimetric properties, particularly with regards to results obtained for quartz grains, which are regarded as being the most reliable in luminescence dating. Supporters of luminescence methods are constantly growing, however, these groups do not always have sufficient knowledge to avoid even the most basic of issues that may be encountered overall – from the process of sampling through to the awareness of what a single luminescence result represents. The present paper provides an overview of several practical aspects of luminescence dating such as correct sampling procedures and all necessary information regarding the calculation of the dose rate and equivalent dose with particular reference to potential problems that occur when the age of the sample is being determined. All these aspects are crucial for obtaining a reliable dating result, on the other hand, they remain a potential source of uncertainty.

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Authors and Affiliations

Piotr Moska
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Abstract

Several conclusions and recommendations concerning sediment trap geometry, the technique of their deployment and interpretation of measurements results are described in this paper. Only cylindrical sediment traps are able to cope with the diverse and dynamic environment of glaciated fjords. The relation between different trap parameters shows the optimal proportion of cylinder diameter as being between 6 and 10 cm and ratio length/diameter not less than 7/1. During the peak of the melting season in Kongsfjorden (Spitsbergen) the rate of sedimentation of total matter reaches over 900 g m–2 d–1 and the velocity of brackish water current can reach 80 cm s–1 on the surface. Owing to the high productivity of Arctic fiords and large concentration of suspended mineral matter it is possible to collect of large samples in a short time, therefore prevention of sediment traps by swimmers is not necessary.

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Authors and Affiliations

Marek Zajączkowski
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Abstract

In the summer of 1977/78, materials for determining the age and growth rate of Pseudochaenichthys georgianus Norman, 1937 were obtained in the South Georgia region. The 11—51 cm long fishes were of the age 1+ to 13+. The curvilinear relationship between the body length and the otolith radius took an S shape. In the first four years annual increments are almost identical and start to decrease in the following years. Spawning may occur in the 5th or 6th year of life, and hatching of larvae from eggs laid in autumn (IV—VI) takes place at the end of winter (IX of X). Larvae and juvenile fish lead an exclusively pelagic life, while older fish feed in near-bottom layers: when resources are scare there they seek food in the pelagial.

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Authors and Affiliations

Juliusz Chojnacki
Piotr Palczewski
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Abstract

Filler surface modification has become an essential approach to improve the compatibility problem between natural fillers and polymer matrices. However, there is limited work that concerns on this particular effect under dynamic loading conditions. Therefore, in this study, both untreated and treated low linear density polyethylene/rice husk composites were tested under static (0.001 s –1, 0.01 s –1 and 0.1 s –1) and dynamic loading rates (650 s –1, 900 s –1 and 1100 s –1) using universal testing machine and split Hopkinson pressure bar equipment, respectively. Rice husk filler was modified using silane coupling agents at four different concentrations (1, 3, 5 and 7% weight percentage of silane) at room temperature. This surface modification was experimentally proven by Fourier transform infrared and Field emission scanning electron microscopy. Results show that strength properties, stiffness properties and yield behaviour of treated composites were higher than untreated composites. Among the treated composites, the 5% silane weight percentage composite shows the optimum mechanical properties. Besides, the rate of sensitivity of both untreated and treated composites also shows great dependency on strain rate sensitivity with increasing strain rate. On the other hand, the thermal activation volume shows contrary trend. For fracture surface analysis, the results show that the treated LLDPE/RH composites experienced less permanent deformation as compared to untreated LLDPE/RH composites. Besides, at dynamic loading, the fracture surface analysis of the treated composites showed good attachment between RH and LLDPE.
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Authors and Affiliations

Mohd Firdaus Omar
1 2
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
1 2
ORCID: ORCID
Sam Sung Ting
1 2
ORCID: ORCID
B. Jeż
3
ORCID: ORCID
M. Nabiałek
3
ORCID: ORCID
Hazizan Md Akil
4
ORCID: ORCID
Nik Noriman Zulkepli
1
ORCID: ORCID
Shayfull Zamree Abd Rahim
1
ORCID: ORCID
Azida Azmi
2
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP),Centre of Excellent Geopolymer & Green Technology (CeGeoGTech), Perlis, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Faculty of Chemical Engineering Technology, Perlis, Malaysia
  3. Częstochowa University of Technology, Faculty of Mechanical Engineering and Computer Science, 42-200 Częstochowa, Poland
  4. Universiti Sains Malaysia, School of Materials and Mineral Resources Engineering, Pulau Pinang, Malaysia
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Abstract

The article considers the issues of the value of invested capital, methods of its measurement and its growth mechanisms. The author draws attention to relationship between the value of capital and the paradigm of economics, which ultimately indicates the existence of connections between the effectiveness of investment and the philosophy of economics. The main purpose of the article is to identify abnormalities in the valuation of assets by investors due to their incorrect or incomplete understanding of the value growth mechanism, the effects of which may assume significance on a macroeconomic scale.

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Authors and Affiliations

Michał Mrowiec
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Abstract

We propose a Bayesian approach to estimating productive capital stocks and depreciation rates within the production function framework, using annual data on output, employment and investment only. Productive capital stock is a concept related to the input of capital services to production, in contrast to the more common net capital stock estimates, representing market value of fixed assets. We formulate a full Bayesian model and employ it in a series of illustrative empirical examples. We find that parameters of our model, from which the time-path of capital is derived, are weakly identified with the data at hand. Nevertheless, estimation is feasible with the use of prior information on the production function parameters and the characteristics of productivity growth. We show how precision of the estimates can be improved by augmenting the model with an equation for the rate of return.
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Authors and Affiliations

Jakub Boratyński
1
Jacek Osiewalski
2

  1. University of Lodz, Lodz, Poland
  2. Cracow University of Economics, Cracow, Poland
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Abstract

Glass and ceramic industries are the main consumption areas of quartz sand, which is a formed as a result of the weathering of igneous metamorphic rocks. In such industries, it is very important to select the correct ball size in order to grind the raw material to the desired particle size in optimum time. In this study, the changes in the specific rate of breakage of the quartz sand sample were investigated by using cylpebs of three different sizes. For this purpose, three different mono-size samples were prepared according to 4√2 series in the range of 0.090-0.053 mm. The quartz sand prepared in these three intervals were ground with 10×10, 20×20 and 30×30 mm cylpebs for different durations. Specific rate of breakage values were obtained from the particle size distributions acquired after various grinding periods. As a result of grinding tests, an increase in rate of breakage is observed due to the increase in cylpebs diameter.
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Bibliography

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[2] SERH AM, Seramik, cam ve çimento hammaddeleri üreticileri derneği 2015-2017 dönemi faaliyet raporu, (2017).
[3] N . Yıldız, Cevher Hazırlama ve Zenginleştirme, Ertem Basım Yayın Dağıtım, Ankara (2014).
[4] S . Haner, The Effects of Ball Size on the Determination of Breakage Parameters of Nepheline Syenite. J. Min. Sci. 56 (5), 848-856 (2020). DOI : https://doi.org/10.1134/S1062739120057191
[5] K.S. Lidell, Machines for Fine Milling to Improve the Recovery of Gold from Calcines and Pyrite. Proceeding of the International Conference on Gold, Johannesburg 405-417 (1986).
[6] J. Bouchard, G. LeBlanc, M. Levesque, P. Radziszewski, D. Georges-Filteau, Breaking down Energy Consumption in Industrial Grinding Mills. In Proceedings 49th Annual Canadian Mineral Processors Operators Conference, 25-35, Canadian Institute of Mining, Metallurgy and Petroleum (2017).
[7] D.W. Fuerstenau, A.-Z.M. Abouzeid, The Energy Efficiency of Ball Milling in Comminution. Int. J. Miner. Process. 67 (1-4), 161-185 (2002). DOI : https://doi.org/10.1016/S0301-7516(02)00039-X
[8] A.K. Schellinger, A Calorimetric Method for Studying Grinding in a Tumbling Medium, Trans. AIME 190, 518- 522 (1951).
[9] M . Vardar, E. Bozkurtoğlu, Yerkabuğunu Oluşturan Maddeler Mineraller ve Kayaçlar. İnşaat Jeolojisi, 2009-2010 Course Year Grades, 20 (2009).
[10] L .G. Austin, K. Shoji, P.T. Luckie, The Effect of Ball Size on Mill Performance. Powder Technol. 14 (1), 71-79 (1976). DOI : https://doi.org/10.1016/0032-5910(76)80009-5
[11] F .C. Bond, Grinding Ball Size Selection. Trans. AIME , 592-595 (1958).
[12] T.S. Yusupov, E.A. Kirillova, G.A. Denisov, Dressing of Quartz-Feldspar Ores on the Basis of Selective Grinding and Mechanical Activation. J. Min. Sci. 39, 174-177 (2003). DOI : https://doi.org/10.1023/B:JOMI.0000008464.34124.1d
[13] W.H. Coghill, F.D. Devaney, Ball Mill Grinding. (1937). https://play.google.com/books/reader?id = k4MbYBy8674C&hl = tr&pg = GBS.PP1,access:15.12.2019
[14] M . Wolosiewicz-Glab, D. Foszcz, T. Gawenda, S. Ogonowski, Design of an Electromagnetic Mill. Its Technological and Control System Structures for Dry Milling. E3S Web of Conferences: Mineral Engineering Conference (MEC 2016), Poland 8 01066 (2016).
[15] K. Barani, H. Balochi, First-order and Second-order Breakage Rate of Coarse Particles in Ball mill Grinding. Physicochem. Probl. Miner. Process. 52 (1), 268-278 (2016). DOI : https://doi.org/10.5277/ppmp160123
[16] K. Barani, H. Balochi, A Comparative Study on the Effect of Using Conventional and High Pressure Grinding Rolls Crushing on the Ball Mill Grinding Kinetics of an Iron Ore. Physicochem. Probl. Miner. Process. 52 (2), 920-931 (2016). DOI : https://doi.org/10.5277/ppmp160231
[17] T.P. Olejnik, Grinding Kinetics of Granite Considering Morphology and Physical Properties of Grains. Physicochem. Probl. Miner. Process. 48 (1), 149-158 (2012).
[18] L .G. Austin, R.R. Klimpel, P.T. Luckie, Process Engineering of Size Reduction: Ball Milling, American Institute of Mining Metallurgical and Petroleum Engineers Inc., New York, United States of America (1984).
[19] L .G. Austin, R. Bagga, M. Çelik, Breakage Properties of Some Materials in a Laboratory Ball Mill. Powder Technol. 28 (2), 235-241 (1981). DOI : https://doi.org/10.1016/0032-5910(81)87049-0.
[20] K. Shoji, L.G. Austin, F. Smaila, K. Brame, P.T. Luckie, Further Studies of Ball and Powder Filling Effects in Ball Milling. Powder Technol. 31 (1), 121-126 (1982). DOI : https://doi.org/10.1016/0032-5910(82)80013-2
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Authors and Affiliations

Serhan Haner
1
ORCID: ORCID

  1. Afyon Kocatepe University, Department of Industrial Product Design, Dinar Yerleşkesi, Cumhuriyet Mh. Kooperat if Cd . No: 1, Dinar, Afyonkarahisar, Turkey
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Abstract

In this study, an old rotational landslide that has reactivated in the NW sector of an open-pit mine operated within the gneiss rock unit was evaluated for geological and hydrogeological properties. The pit slopes were susceptible to mass movement when there were variations in water inflows. Considering this fact, a conceptual numerical model concerning geostructural features, rainfall infiltration, and varying hydrological conditions was constructed. Initially, finite element (FE) groundwater seepage analyses were performed to evaluate the effect of water flow on stability in the dry and rainy seasons. The rainy season was simulated by vertical infiltration. Since the dewatering measures are of importance in open pit slope instability mitigation, pumping wells were designed to control water flow through the disturbed zone to improve the stability of the sector that can be triggered again with changing environmental conditions. The performance and organization of the pumping wells were also simulated in the FE model. This FE model was part of a dewatering plan. From this, the effect of the pumping rate from the wells on the stability of the sector was revealed. It was also found that there should be an increase in the pumping rate in the rainy season.
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Authors and Affiliations

Tümay Kadakci Koca
1
ORCID: ORCID

  1. Muğla Sıtkı Koçman University, Turkey
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Abstract

In this article, gold is analyzed from an investment perspective as an asset that allows you to increase your wealth. The analysis is twofold. First, it is about examining to what extent changes in gold prices in the world markets translate into changes in the prices of shares of companies that extract gold. Second, it was checked whether there is a financial leverage effect, which in this case means that changes in the price of shares of gold mining companies are greater than changes in the price of gold itself. Methodically, the Sharpe model was used and two basic parameters of the model were estimated, i.e. the intercept (alpha), and the beta coefficient as a measure of systematic risk, for the gold market and the equity market of gold mining companies and ET Fs based on these companies.
The research carried out in accordance with the logic of the Sharpe model shows that the obtained value of the alpha parameter for the stock market was positive, while for the gold market it was negative. At the same time, higher levels of this parameter are beneficial to the investor, which means that an advantage of the stock market over the gold market exists. In turn, the estimated beta for the stock market is much lower than for the gold market. The systematic risk level for stocks is 0.45, and for the gold market it is 1.98, which is a significant difference. The stocks of gold mining companies can be classified as defensive against the stock market (the rate of return of the gold mine stock is insensitive to market movements) and aggressive against the gold market (the rate of return of the gold mine shares reacts more strongly than the movement in the price of gold).
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Authors and Affiliations

Mikołaj Baranowski
1
Krystian Pera
1
ORCID: ORCID

  1. University of Economics, Katowice, Poland
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Abstract

The paper deals with the issue of financial efficiency, measured by the arithmetic rate of return, of indirect financial investments in the area of strategic raw materials (hard coal, copper, crude oil). Two forms of indirect investments were analyzed: shares of natural resources companies listed on the Warsaw Stock Exchange and futures contracts for strategic commodities: hard coal, copper and crude oil.

The time of the analysis is the first 6 months of 2019 and 2020. The year 2019 was regarded as an analysis of the period of economic growth, and the year 2020 was the analysis of the period of economic crisis. The comparisons were made in two dimensions. Firstly, it whether indirect commodity investments show the characteristics of efficiency resilience to the time of the economic crisis was checked (by comparing the achieved rates of return in the two analyzed periods). Secondly, which of the analyzed forms of investment (stocks, contracts) gives better investment results during economic growth and economic crisis was compared.

As it was shown in the paper, indirect commodity investments do not show an above-average rate of return neither during economic growth nor economic crisis. The achieved rates of return on shares compared to changes in the WIG20 index in the analyzed first half of 2019 were negative. Only one company showed a positive and significantly higher than the market rate of return. Very similar results were achieved by the analyzed companies in 2020.

On the other hand, the analysis of prices and rates of return on commodity futures contracts showed that in the period of economic growth it is effective to take a long position on crude oil contracts and a short position on hard coal contracts. In a period of economic crisis, the opposite position is profitable due to the observed growth in hard coal prices and a significant drop in crude oil prices.

The answers to the research questions posed in the paper do not provide indications for recommending indirect forms of investment in commodities as an alternative to analogous forms of other sectors of the economy. The analysis shows that the impact of the economic situation on the efficiency of commodity investment is most noticeable for crude oil, and the least (among the analyzed commodities) for indirect copper-based investments.

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Authors and Affiliations

Krystian Pera
ORCID: ORCID
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Abstract

The choice of financing sources made by coal mining companies reflects a number of macro- and microeconomic factors. The paper attempts to present only those that play the most important role in mining companies’ market activities. The structure of sources of financing mining companies’ operations is presented by computing the share of equity in liabilities and shareholders’ equity, the golden balance sheet rule showing the degree of financing of non-current assets through shareholders’ equity and the silver balance sheet rule which shows the ratio of long-term capital to non-current assets. Only a few mining companies can satisfy those two rules as they finance their economic activity through equity and short-term liabilities. Mining companies are not indebted. Their caution in incurring long- -term debt results from the implementation of high volatility of financial results, which are prone to the effects of the economic situation. The basic determinants of the choice of financing sources include the structure of assets, the rate of return on assets and companies’ ability to service debt. The high capital intensity of the mining sector is reflected in the large share of non-current assets in total assets, which in some mining companies exceeds 80% of total assets. The rates of return on assets vary widely and are influenced by fluctuations in coal prices at different phases of the market situation. They also have a significant impact on companies’ ability to service debt. Empirical research conducted by the author revealed that the structure of financing sources in Polish coal mining companies is like that of global mining corporations, as are the economic relations shaping this structure.
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Authors and Affiliations

Marta Sierpińska
1
ORCID: ORCID

  1. University of Economics and Human Sciences in Warsaw, Poland
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Abstract

Cut-off grades optimization is a fundamental issue for mineral deposits. A cut-off grade is any grade that is used to separate two courses of action; to mine or not to mine, to process or to dump. In order to achieve the maximum discounted cash flow, generally a decreasing order of cut-off grades schedule takes place. Variable mining costs are applied to the extracted material, not to all of the depletion rate as some of the depletion can be left in-situ. B ecause of access constraints, some of the blocks that have an average grade less than the determined cut-off grade are left in-situ, some of them are excavated and dumped as waste material. The probability density function of an exponential distribution is used to find the portion of the material below the cut-off used that is left in situ. The parts of a mineral deposit that are excavated but will be dumped as waste material and tailings of ore incur some additional cost of rehabilitation. The method of memetic algorithms is a very robust optimization tool. It is a step further from the genetic algorithms. The crossover, mutation and natural selection behavior of the method ensures it escape from a local optimum point, and a further local search improves the optimum further. This paper describes the general problem of cut-off grades optimization, outlines the use of memetic algorithms in cut-off grades optimization and further extension of the method including partial depletion rates and variable rehabilitation cost. This paper is the first application of memetic algorithms to cut-off grades optimization in this context.
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Bibliography

Cetin, E . 2016. Cut-off grades optimization by means of memetic algorithms with uncertain market conditions. Middle East Journal of Technic 1(1).
Cetin, E . and Dowd, P. A. 2002. The use of genetic algorithms for multiple cut-off grade optimisation. Proceedings of the 30th International Symposium on the Application of Computers and Operations Research in the Minerals Industries, Littleton, Colorado, USA.
Cetin, E . and Dowd, P.A. 2016. M ultiple cut-off grade optimization by genetic algorithms and comparison with grid search method and dynamic programming. The Journal of the South African Institute of Mining and Metallurgy 116(7), pp. 681–688, DOI: 10.17159/2411-9717/2016/v116n7a10.
Dowd, P.A. 1976. Application of dynamic and stochastic programming to optimise cut-off grades and production rates. Transactions of the Institution of Mining and Metallurgy Section A: Mining Industry 81. pp. 160–179.
Dawkins, R. 1976. The Selfish Gene, Oxford University Press.
Garg, P. 2009. A Comparison between Memetic algorithm and Genetic algorithm for the Cryptanalysis of Simplified Data Encryption Standard Algorithm. International Journal of Network Security & Its Applications (IJNSA), 1(1), pp. 34–42.
Gholamnejad, J. 2008. Determination of the optimum cutoff grade considering environmental cost. Journal of International Environmental Application and Science 3(3), pp. 186-194.
Gholamnejad, J. 2009. Incorporation of rehabilitation cost into the optimum cut-off grade determination. The Journal of the South African Institute of Mining and Metallurgy 109(2), pp. 89–94.
Holland, J.H. 1975. Adaptation in N atural and Artificial Systems. University of Michigan Press, USA.
Lane, K.F. 1964. Choosing the optimum cutoff grade. Colorado School of Mines Quarterly 59(4), pp. 811–829.
Lane, K.F. 1988. The Economic Definition of Ore. Mining Journals Books Ltd., L ondon, UK.
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Authors and Affiliations

Erhan Cetin
1
ORCID: ORCID
Abdurrahman Dalgic
2

  1. Dicle University, Diyarbakır, Turkey
  2. Alanya Alaaddin Keykubat University, Alanya, Turkey

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