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Abstract

New types of models can help us better predict how well species will be able to adapt to climate change.
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Authors and Affiliations

Katarzyna Sękiewicz
1

  1. Department of Biogeography and SystematicsInstitute of Dendrology PAS in Kórnik
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Abstract

This paper deals with computer modelling of the retention of a synthetic diamond particle in a metallic matrix produced by powder

metallurgy. The analyzed sintered powders can be used as matrices for diamond impregnated tools. First, the behaviour of sintered cobalt

powder was analyzed. The model of a diamond particle embedded in a metallic matrix was created using Abaqus software. The

preliminary analysis was performed to determine the mechanical parameters that are independent of the shape of the crystal. The

calculation results were compared with the experimental data. Next, sintered specimens obtained from two commercially available powder

mixtures were studied. The aim of the investigations was to determine the influence of the mechanical and thermal parameters of the

matrix materials on their retentive properties. The analysis indicated the mechanical parameters that are responsible for the retention of

diamond particles in a matrix. These mechanical variables have been: the elastic energy of particle, the elastic energy of matrix and the

radius of plastic zone around particle.

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Authors and Affiliations

J. Borowiecka-Jamrozek
J. Lachowski
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Abstract

Hydrological modelling uses modern computational methods to simulate local and regional water circulation systems. How does this work, and what benefits does it bring?

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Authors and Affiliations

Monika Okońska
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Abstract

This paper describes modifications of the Mayr and Cassie models of the electric arc. They include the phenomena of increased heat dissipation and non-zero residual conductance when the current passes through zero. The modified models are combined into a new hybrid model connecting them in parallel and activated by a weight function. Two cases of functional dependence of models on current intensity and instantaneous conductance are considered. Mathematical models in differential and integral forms are presented. On their basis, computer macromodels are created and simulations of processes in circuits with arc models are performed. The families of static and dynamic arc voltage and current characteristics are presented.
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Bibliography

[1] King-Jet Tseng,YaomingWang D., MahindaVilathgamuwa, An experimentally verified hybrid Cassie- Mayr electric arc model for power electronics simulations, IEEE Transactions on Power Electronics, vol. 12, no. 3, pp. 429–436 (1997), DOI: 10.1109/63.575670.
[2] Sawicki A., Haltof M., Spectral and integral methods of determining parameters in selected electric arc models with a forced sinusoid current circuit, Archives of Electrical Engineering, vol. 65, no. 1, pp. 87–103 (2016), DOI: 10.1515/aee-2016-0007.
[3] Pentegov I.V., Sidorec V.N., Comparative analysis of models of dynamic welding arc, The Paton Welding Journal, no. 12, pp. 45–48 (2015), DOI: 10.15407/tpwj2015.12.09.
[4] Kalasek V., Measurements of time constants on cascade d.c. arc in nitrogen, TH-Report 71-E18, Eindhoven, pp. 1–30 (1971).
[5] Sawicki A., The universal Mayr–Pentegov model of the electric arc, Przegl˛ad Elektrotechniczny (Electrical Review), vol. 94, no. 12, pp. 208–211 (2019), DOI: 10.15199/48.2019.12.47.
[6] Katsaounis A., Heat flow and arc efficiency at high pressures in argon and helium tungsten arcs, Welding Research Supplement I, September, pp. 447-s–454-s (1993).
[7] Maximov S., Venegas V., Guardado J.L., Melgoza E., Torres D., Asymptotic methods for calculating electric arc model parameters, Electrical Engineering, vol. 94, no. 2, pp. 89–96 (2012), DOI: 10.1007/s00202-011-0214-6.
[8] Sawicki A., Arc models for simulating processes in circuits with a SF6 circuit breaker, Archives of Electrical Engineering, vol. 68, no. 1, pp. 147–159 (2019), DOI: 10.24425/aee.2019.125986.
[9] Sawicki A., Classical and Modified Mathematical Models of Electric Arc, Institute ofWelding Bulletin, no. 4, pp. 67–73 (2019), DOI: 10.17729/ebis.2019.4/7.
[10] Janowski T., Jaroszynski L., Stryczewska H.D., Modification of the Mayr’s electric arc model for gliding Arc Analysis, XXVI International Conference on Phenomena in Ionized Gases, Nagoya, Japan 2001/7/17, pp. 341–342 (2001).
[11] Ziani A., Moulai H., Hybrid model of electric arcs in high voltage circuit breakers, Electric Power Systems Research, vol. 92, pp. 37–42 (2012), DOI: 10.1016/j.epsr.2012.04.021.
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Authors and Affiliations

Antoni Sawicki
1
ORCID: ORCID

  1. Association of Polish Electrical Engineers (NOT-SEP), Czestochowa Division, Poland
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Abstract

Mathematical models of electric an arc with disturbed geometric sizes were created based on initial assumptions adopted from theMayr and Cassie models. Two cases of approximation of arc characteristics were considered separately. The Mayr–Voronin model was created in the low-current range with an exponential dependence of conductance on plasma enthalpy. However, the Cassie–Voronin model created is valid in the high-current range with a linear dependence of conductance on plasma enthalpy. In addition, the effect of two different assumptions about the method of energy dissipation, proportional to the lateral surface of the column or proportional to the volume of the column, on the parameters of both mathematical models was compared. It has been shown that under constant geometrical parameter values, created models can be reduced to classic Mayr and Cassie models. Then, these modelswere modified by taking into account the additional increase in heat dissipation as the current increases. Increasing voltage and current characteristics correspond to such an arc. Using the computer simulations, the effectiveness of using developed mathematical models in mapping the dynamic characteristics of the electric arc has been shown.
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Bibliography

[1] Krouchinin A.M., Sawicki A., Modelling of the constricted arc in plasma generators, Monographs series, no. 109, The Publishing Office of Częstochowa University of Technology, Częstochowa (2005).
[2] Solonenko O.P., Thermal Plasma Torches and Technologies, Cambridge International Science Publishing, vol. 1 (2000).
[3] Jaroszynski L., Stryczewska H.D., Computer simulation of the electric discharge in GlidArc plasma reactor, 3rd International Conference: Electromagnetic devices and processes in environment protection ELMECO-3, pp. 31–36 (2000).
[4] Schavemaker P.H., van der Sluis L., An Improved Mayr-Type Arc Model Based on Current-Zero Measurements, IEEE Trans. Power Delivery, vol. 15, no. 2, pp. 580–584 (2000).
[5] Kopersak V.M., The theory of welding processes – 1, KPI (in Ukrainian), Kiev (2011).
[6] Zalessky A.M., Fundamentals of the theory of electrical apparatus, Higher School Publishing House (in Russian), Moscow (1974).
[7] Taev I.S., Electrical contacts and arcing devices of low voltage devices, Energy Publishing House (in Russian), Moscow (1973).
[8] Marciniak L., Dynamic models of short-circuit arc for networks with low ground fault current, Energy Archive (in Polish), vol. 37, pp. 357–67 (2007).
[9] Ziani A., Moulai H., Hybrid model of electric arcs in high voltage circuit breakers, Electric Power Systems Research, vol. 92, pp. 37–42 (2012).
[10] Voronin A.A., Improving the efficiency of contact-extinguishing systems of high-current switching devices with an extending arc, Abstract of thesis (in Russian), Samara (2009).
[11] Ciok Z., Mathematical models of connecting arc,Warsaw University of Technology (in Polish),Warsaw (1995).
[12] Sawicki A., Models of adjustable length electric arc,Wiadomosci Elektrotechniczne (in Polish), no. 7, pp. 15–19 (2012).
[13] Berger S., Mathematical approach to model rapidly elongated free-burning arcs in air in electric power circuits, ICEC 2006, 6–9 June 2006, Sendai, Japan (2006).
[14] Pentegov I.V., Sydorets V.N., Comparative analysis of models of dynamic welding arc, The Paton Welding Journal, no. 12, pp. 45–48 (2015).
[15] Sawicki A., The universal Mayr–Pentegov model of the electric arc, Electrical Review, vol. 94, no. 12, pp. 208–211 (2019), DOI: 10.15199/48.2019.12.47.
[16] Krouchinin A.M., Sawicki A., A theory of electrical arc heating, The Publishing Office of Technical University of Częstochowa, Częstochowa (2003).
[17] Sawicki A., Arc models for simulating processes in circuits with a SF6 circuit breaker, Archives of Electrical Engineering, vol. 68, no. 1, pp. 147–159 (2019), DOI: 10.24425/aee.2019.125986.
[18] Katsaounis A., Heat flow and arc efficiency at high pressures in argon and helium tungsten arcs, Welding Research Supplement I, pp. 447-s- 454-s (1993).
[19] Kalasek V., Measurements of time constants on cascade d.c. arc in nitrogen, TH-Report 71-E18, Eindhoven, pp. 1–30 (1971).
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Authors and Affiliations

Antoni Sawicki
1
ORCID: ORCID

  1. Association of Polish Electrical Engineers (NOT-SEP), Czestochowa Division, Poland
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Abstract

The short outlook at main problems related to pollutant migration modelling in the granular layer is critically discussed in the paper. The general model of pollutant migration in granular was transposed into dimensionless form. The general model was adapted to describe the examined decontamination technology and two operational models were differentiated due to the dominant mass transfer resistances in the system. The verification validated the functional effectiveness of the suggested model and its numerical implementation under different conditions. It approves the possibility of the practical application of the proposed method. The problem of influence of irregular distribution of negative mass sources (sorptivc agglomerates) on mass transport in the granular layer was underlined.
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Authors and Affiliations

Anna Adach
Stanisław Wroński
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Abstract

Modern geological maps are 3D, or even 4D models representing the complex structure of the Earth. They interpret a variety of geological information and represent it in graphical form.
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Authors and Affiliations

Joanna Rychel
1
Łukasz Nowacki
1
Mirosław Kamiński
1

  1. Polish Geological Institute – National Research Institute in Warsaw
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Abstract

The article presents the results of model research concerning the change of technology of argon blowing into liquid steel at the ladle furnace, using the dual plug system. The results of numerical simulations were verified with experimental data carried out on the water model device. The verified model was used to perform numerical simulations to predict the impact of using a new gas injection technology – with different flow rates – on the time to achieve the assumed degree of metal chemical homogenization after alloy addition. Simulation results show that argon blowing metal bath in dual plug mode can effectively reduce mixing time compared to conventional technology with the same gas flow rates. Generally, the use of the dual plug system is beneficial for reducing the bath mixing time, however, the assumed optimal proportion of gas blown through individual plug should be followed. Finally, numerical predictions were used to perform experimental melt under industrial conditions. Industrial verification has clearly confirmed the validity of numerical modeling and showed that also in industrial conditions, a shorter time of chemical homogenization was obtained for the dual plug system.
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Authors and Affiliations

M. Warzecha
1
A. Hutny
1
P. Warzecha
1
Z. Kutyła
2
T. Merder
3

  1. Czestochowa University of Technology, Faculty of Production Engineering and Materials Technology, 19 Armii Krajowej Av., 42-200 Czestochowa, Poland
  2. CMC Poland Sp. z o.o., 82 Piłsudskiego Str., 42-400 Zawiercie, Poland
  3. Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, 8 Krasinskiego Str., 40-019 Katowice, Poland
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Abstract

Coagulation is a process during which a flocculent suspension may sediment. It is characterized by its polydisperse structure. There are three main fractions of sedimentation particles after coagulation: spherical, non-spherical and porous agglomerates. Each of the fractions sediments in a different manner, for different forces act on them, due to interactions between the particles, inhibition or entrainment of neighboring particles. The existing sedimentation models of polydisperse suspension do not consider the flocculation process, i.e. the change of one particle into another during sedimentation, resulting from their agglomeration. The presented model considers the shape of particles and flocculation, which is a new approach to the description of the mathematical process of sedimentation. The velocity of sedimentation depends on the concentration of particles of a given fraction in a specific time step. Following the time step, the heights of individual fractions are calculated. Subsequently, new concentration values of individual fractions are determined for the correspondingly reduced volume of occurrence of a given fraction in the volume analyzed, taking particle flocculation into consideration. The new concentration values obtained in this way allow to recalculate the total sedimentation rates for the next time step. Subsequent iterations allow for numerical simulation of the sedimentation process.
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Bibliography

  1.  Z. Su et al., “Coagulation of Surface water: Observations of the significance of biopolymers,” Water Res., vol. 126, pp. 144–152, 2017, doi: 10.1016/j.watres.2017.09.022.
  2.  L. Postolachi et al., “Improvement of coagulation process for the Prut River water treatment using aluminum sulphate,” Chem. J. Mold., vol. 10, no. 1, pp. 25–32, 2015, doi: 10.3923/jest.2017.268.275.
  3.  D. Mroczko and I. Zimoch, “Coagulation of pollutions occurring in surface waters during time of dynamic water flow,” Ecol. Eng., vol. 19, no. 2, pp. 15–22, 2018, doi: 10.12911/22998993/118273.
  4.  S. Janiszewska, “Comparison of coagulation methods and electrocoagulation in purification model gray water,” Eko-Dok, vol. 26, pp. 223– 229, 2012.
  5.  I. Krupińska and A. Konkol, “The influence of selected technological parameters on the course and effectiveness of coagulation in graund water treatment”, Uniwersytet Zielonogórski, Zeszyty Naukowe, Environmental Egineering, vol. 37, no. 157, pp. 36–52, 2015.
  6.  T.E. Dutkiewicz, Fizykochemia powierzchni, Wydawnictwa Naukowo-Techniczne, Warsaw, 1998.
  7.  R. Wardzyńska, L. Smoczyński, R. Wolicki, B. Załęska-Chróst, and Z. Bukowski, “Computer simulation of flocculation and chemical coagulation,” Ecol. Chem. Eng., vol. 17, no. 12, pp.  1663–1672, 2010.
  8.  B. Joon Lee and F. Molz, “Numerical simulation of turbulenceinduced flocculation and sedimentation in a flocculent-aided sediment retention pond,” Environ. Eng. Res., vol. 19, no. 2, pp. 165–174, 2014, doi: 10.4491/eer.2014.19.2.165.
  9.  M.A. Goula, M. Kostoglou, D.T. Karapantsios, and I.A. Zoubolis, “A CFD methodology for the design of sedimentation tanks in potable water treatment, Case study: The influence of a feed flow control baffle,” Chem. Eng. J., vol. 140, pp. 110–121, 2008, doi: 10.1016/j. cej.2007.09.022.
  10.  L.A. Kowal and M. Świderska-Bróż, Water Treatment, Polish Scientific Publishers PWN, Warsaw–Wroclaw, 2000.
  11.  P.W. Atkins, Physical chemistry, Polish Scientific Publishers PWN, Warsaw, 2007.
  12.  W.T. Hermann, Physical chemistry, Wydawnictwo lekarskie PZWL, Warsaw, 2007.
  13.  S. Berres, R. Bürger, and M.E. Tory, “Applications of polydisperse sedimentation models,” Chem. Eng. J., vol. 111, no.  2–3, pp. 105–117, 2005.
  14.  R. Błażejewski, Sedimentation of solid particles. Fundamentals of theory with examples of applications, Polish Scientific Publishers PWN, Warsaw, 2015.
  15.  J. Bandrowski, H. Merta, and J. Zioło, Sedimentation of suspensions. Rules and design, Silesian University of Technology Publisher, Gliwice, 1995.
  16.  M. Dziubiński and J. Prywer, Mechanics of two-phase fluids, WNT publisher, Warsaw, 2018.
  17.  Z. Orzechowski, J. Prywer, and R. Zarzycki, Fluid mechanics in engineering and environmental protection, Scientific and Technical Publishers, Warsaw 2009.
  18.  K.D. Basson, S. Berres, and R. Bürger, “On models of polydisperse sedimentation with particle-size-specific hindered-settling factors,”Appl. Math. Modell., vol. 33, no. 4, pp. 1815–1835, 2009, doi: 10.1016/j.apm.2008.03.021.
  19.  M. Bargieł, A.R. Ford, and M.E. Tory, “Simulation of sedimentation of polydisperse suspensions: A particle-based Approach,” AIChE J., vol. 51, no. 9, pp. 2457–2468, 2005.
  20.  S.P. Antal, R.T. Lahey, and L.E. Flaherty, “Analysis of Phase Distribution in Fully Developed Laminar Bubbly Two-Phase Flow,” Int. J. Multiphase Flow, vol. 17, pp. 635, 1991, doi: 10.1016/0301-9322(91)90029-3.
  21.  J.F. Richardson and W.N. Zaki, “Sedimentation and Fluidization. Part 1,” Trans. Inst. Chem. Eng., vol. 32, pp. 35–53, 1954.
  22.  J.F. Richardson, J.H. Harker, and J.R. Backhurst, Chemical engineering, vol.2 – Particle Technology and Separtion Processes, Butterworth- Heinemann, 2002.
  23.  J. Garside and M.R. Al-Dibouni, “Velocity-voidage relationship for fluidization and sedimentation in solid-liquid systems,” Ind. Eng. Chem. Process Des. Dev., vol. 16, pp. 206–214, 1977, doi: 10.1021/i260062a008.
  24.  J. Happel and N. Epstein, “Viscous flow in multiparticle systems: cubical assemblage of uniform spheres,” Ind. Eng.Chem., vol. 46, pp. 1187–1194, 1954.
  25.  F. Barnea and J. Mizrahi, “A generalized approach of fluid dynamics of particulate system. Part I. General correlation for fluidization and sedimentation in solid multiparticle systems,” J. Fluid Mech., vol. 52, no. 2, pp. 245–268, 1973.
  26.  E. Barnea and J. Mizrahi, “A generalized approach to the fluid dynamics of particulate systems: General correlation for fluidization and sedimentation in solid multiparticle systems,” The Chem. Eng. J., vol. 5, no. 2, pp. 171–189, 1973, doi: 10.1016/0300-9467(73)80008-5.
  27.  P.M. Biesheuvel, H. Verweij and V. Breedveld, “Evaluation of instability criterion for bidisperse sedimentation,” AIChE J., vol. 47, no. 1, pp. 45–52, 2001, doi: 10.1002/aic.690470107.
  28.  V.S. Patwardhan and C. Tien, “Sedimentation and fluidization in solid-liquid systems: A simple approach,” AIChE J., vol. 31, no. 1, pp. 146–149, Jan. 1985, doi: 10.1002/aic.690310117.
  29.  M. Syamlal and T.J. O’Brien, “Simulation of granular layer inversion in liquid fluidized beds,” Int. J. Multiphase Flow, vol. 14, no. 4, pp. 473–481, 1988, doi: 10.1016/0301-9322(88)90023-7.
  30.  T.N. Smith, “The differential sedimentation of particles of two different spacies,” Inst. Chem. Eng. Trans., vol. 43, pp. T69–T73, 1965.
  31.  P. Krishnamoorthy, “Sedimentation model and analysis for differential settling of two-particle-size suspensions in the Stokes region,” Int. J. Sediment Res., vol. 25, no. 2, pp. 119–133, 2010, doi: 10.1016/S1001-6279(10)60032-7.
  32.  J. Bandrowski, H. Merta and J. Zioło, Sedimentation of suspensions, principles and design, Silesian University of Technology Publisher, Gliwice, 1995.
  33.  J.F. Richardson and F.A. Shabi, “The determination of concentration distribution on sedimenting suspension using radioactive solids,” Transactions of the Institution of Chemical Engineers, vol. 38, pp. 33–41, 1960.
  34.  T.N. Smith, “The differential sedimentation of particles of various species,” Transactions of the Institution of Chemical Engineers, vol. 45, pp. T311–T313, 1967.
  35.  B. Xue and Y. Sun, “Modeling of sedimentation of polydisperse spherical beads with a broad size distribution,” Chem. Eng. Sci., vol. 58, pp. 1531–1543, 2003, doi: 10.1016/S0009-2509(02)00656-5.
  36.  Y. Zimmels, “Theory of hindered sedimentation of polydisperse mixtures,” AIChE J., vol. 29, no. 4, pp. 669–676, 1983, doi: 10.1002/ AIC.690290423.
  37.  J. Happel, “Viscus flow in multiparticle systems: slow motion of fluids relative to beds of spherical particles,” AIChE J., vol. 4, no. 2, pp. 197–201, 1958.
  38.  S.F. Chien, “Settling Velocity of Irregularly Shaped Particles, Society of Petroleum Engineers,” SPE Drill. Complet., vol. 4, no. 04, pp. 281–289, 1994, doi: 10.2118/26121-PA.
  39.  G.H. Ganser, “A Rational Approach to Drag Prediction of Spherical and Non-Spherical Particles,” Powder Technol., vol. 77, no.  2, pp. 143–152, 1993, doi: 10.1016/0032-5910(93)80051-B.
  40.  A. Haider and O. Levenspiel, “Drag Coefficient and Terminal Velocity of Spherical and Non-Spherical Particles,” Powder Technol., vol. 58, no. 1, pp. 63–70, 1989, doi: 10.1016/0032-5910(89)80008-7.
  41.  L. Rosendahl, “Using a multi-parameter particle shape description to predict the motion of non-spherical particle shapes in swirling flow,” Appl. Math. Modell., vol. 24, no. 1, pp. 11‒25, 2000, doi: 10.1016/S0307-904X(99)00023-2.
  42.  M. Zastawny, G. Mallouppas, F. Zhao, and B. van Wachem, “Derivation of drag and lift force and torque coefficients for nonspherical particles in flows,” Int. J. Multiphase Flow, vol. 39, pp 227‒239, 2012, doi: 10.1016/j.ijmultiphaseflow.2011.09.004.
  43.  A. Hölzer and M. Sommerfeld, “New simple correlation formula for the drag coefficient of non-spherical particles,” Powder Technol., vol. 184, no. 3, pp. 361–365, June 2008, doi: 10.1016/j.powtec.2007.08.021.
  44.  R. Barati, S.A. Neyshabouri, and G. Ahmadi, “Issues in Eulerian– Lagrangian modeling of sediment transport under saltation regime,” Int. J. Sediment Res., vol. 33, no. 4, pp. 441–461, 2018, doi: 10.1016/j.ijsrc.2018.04.003.
  45.  B. Oesterle and B. Dinh, ”Experiments on the lift of a spinning sphere in the range of intermediate Reynolds numbers,” Exp. Fluids, vol. 25, no.1, pp. 16–22, 1998, doi: 10.1007/s003480050203.
  46.  I. Mema, V.V. Mahajan, B W. Fitzgerald, and J.T. Padding, “Effect of lift force and hydrodynamic torque on fluidisation of nonspherical particles,” Chem. Eng. Sci., vol. 195, no. 23, pp. 642– 656, 2019, doi: 10.1016/j.ces.2018.10.009.
  47.  S.K.P. Sanjeevi, J.A.M. Kuipers, and J.T. Padding, “Drag, lift and torque correlations for non-spherical particles from Stokes limit to high Reynolds numbers,” Int. J. Multiphase Flow, vol.  106, pp. 325–337, 2018, doi: 10.1016/j.ijmultiphaseflow.2018.05.011.
  48.  S.F. Hoerner, Fluid-dynamic drag, Published by the Autor, 1965.
  49.  R. Ouchene, M. Khalij, B. Arcen, and A. Tanière, “A new set of correlations of drag, lift and torque coefficients for non-spherical particles and large Reynolds numbers,” Powder Technol., vol. 303, pp. 33–43, 2016, doi: 10.1016/j.powtec.2016.07.067.
  50.  M. Leva, M. Weintraub, M. Grummer, M. Pollchik, and H.H. Storsh, “Fluid flow through packed and fluidized systems,” Bull. U. S. Min. Bur., vol. 504, 1951.
  51.  V. Saritha, N. Srinivas, and N.V. Srikanth Vuppala, “Analysis and optimization of coagulation and ?occulation process,” Appl. Water Sci., vol. 7, pp. 451–460, 2017, doi: 10.1007/s13201-014-0262-y.
  52.  M. Smoluchowski, “Versuch einer mathematischen theorie der koagulationskinetic,” Kolloider Lsungen Zeitschrift für Physikalische Chemie, vol. 92, pp. 129–168, 1917.
  53.  H. Müller, “Zur allgemeinen teorie der raschen koagulation,” Kolloidbeihefte, vol. 27, pp. 223‒250, 1928.
  54.  F.S. Torrealba, A Continuous mathematical model of the one-dimensional sedimentation process of flocculated sediment particles, University of Kentucky Doctoral Dissertations, 2010.
  55.  D. Miedzińska, T. Niezgoda, E. Małek, and Z. Zasada, “Study on coal microstructure for porosity levels assessment,” Bull. Pol. Acad. Sci. Tech. Sci., vol. 61, no. 2, pp. 499–505, doi: 10.2478/bpasts-2013-0049.
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Authors and Affiliations

Mariusz Rząsa
1
ORCID: ORCID
Ewelina Łukasiewicz
2
ORCID: ORCID

  1. Department of Computer Science, Opole University of Technology, ul. Oleska 48, 45-052 Opole, Poland
  2. Department of Thermal Engineering and Industrial Facilities, Opole University of Technology, ul. St. Mikołajczyka 5, 45-271 Opole, Poland
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Abstract

In 2015 an important part of the official evaluation of Polish scientific journals was left to experts’ judgement. In this paper we try to establish which observable factors (with available data) are closely related to the outcome of experts’ evaluation of Polish journals in economic sciences. Using the multiple regression statistical model we show that only 5 variables (out of 17) significantly explain almost 50% of the empirical variance of the experts’ evaluation. The determinants of particular interest, not entering the formal criteria and not related to the impact on global science, are: the number of citations mainly in Polish journals and the affiliation with the Polish Academy of Sciences.

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Authors and Affiliations

Jacek Osiewalski
Anna Osiewalska
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Abstract

The article concerns computer modelling of processes in cooling systems of internal combustion engines. Modelling objectives and existing commercial programs are presented. It also describes Author’s own method of binding graphs used to describe phenomena in the cooling system of a spark ignition engine. The own model has been verified by tests on the engine dynamometer. An example of using a commercial program for experimental modelling of an installation containing a heat accumulator is presented.

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Authors and Affiliations

Zbigniew Kneba
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Abstract

Prof. Daniel Wójcik from the Nencki Institute of Experimental Biology explains the principles of brain modelling

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Authors and Affiliations

Daniel Wójcik
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Abstract

Mathematical models offer certain solutions to social problems, but implementing them in practice may spark certain controversies – says Prof. Piotr Dworczak from Northwestern University.
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Authors and Affiliations

Piotr Dworczak
1

  1. Northwestern University
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Abstract

We discuss econometric modeling with Prof. Aleksander Welfe from the University of Łódź and Warsaw School of Economics (SGH), Vice-President of the Polish Academy of Sciences.
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Authors and Affiliations

Aleksander Welfe
1

  1. Vice-President of the Polish Academy of Sciences
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Abstract

In this paper, we show that the signal sampling operation considered as a non-ideal one, which incorporates finite time switching and operation of signal blurring, does not lead, as the researchers would expect, to Dirac impulses for the case of their ideal behavior.
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Authors and Affiliations

Andrzej Borys
1
ORCID: ORCID

  1. Gdynia Maritime University, Poland
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Abstract

This paper introduces security assessment methodology for isolated single-workstation multilayer systems processing sensitive or classified data according with a corresponding security model for such system. The document provides a high-level tool for systematizing certain-class-systems security models development. The models based on the introduced methodology cover data confidentiality and availability attributes protection on a sufficient level.

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Authors and Affiliations

Daniel Wiechecki
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Abstract

This paper deals with the subject of high temperature analysis of refining slags originating from a ladle from an actual/industrial secondary refining process. The objective of the conducted research was to learn about the rheological behaviour of the complex industrial slag systems analysed in conditions of variable rheological parameters and temperature, also analyses with a high-temperature microscope. The analysed system seems to be a Newtonian body (with viscosity between 0.1 and 0.8 Pa·s, depend on temperature value, and chemical composition).
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Authors and Affiliations

M. Ślęzak
1
ORCID: ORCID
M. Karbowniczek
1
ORCID: ORCID
P. Migas
1
ORCID: ORCID
W. Ślęzak
1
ORCID: ORCID

  1. AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland
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Abstract

The aim of this research was to determine the embryotoxic and teratogenic effects and lethal dose (LD50) of maropitant in ovo, using fertile chicken eggs. The study was designed in two stages, CHEST-I and CHEST-II. For CHEST-I, 210 fertile eggs were divided into seven equal groups; control, saline solution and 5 different doses of maropitant (10, 5, 2.5, 1.25, 0.625 mg/kg) injected groups. For CHEST-II, 150 fertile eggs were divided into five equal groups; control, saline solution and 3 different doses of maropitant (8, 6, 4 mg/kg)-injected groups. Eggs were opened on day 21 of incubation. Maropitant did not cause teratogenicity at any dose, while higher embryonic death rates were observed at doses above 4 mg/kg. The LD50 dose of maropitant was determined as 7.24 mg/kg. In conclusion, maropitant should only be used after full consideration of risks and benefits in pregnancy.
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Bibliography


Cada DJ, Levien T, Baker DE (2003) Aprepitant. Hosp Pharm 38: 763-774.
Canbar R, Uslu M, Tufan O, Yazar E (2021) Determination of embryotoxic dose limit of detomidine with in-ovo model. Eurasian J Vet Sci 37: 71-75.
El-Bahri L (2009) Maropitant: A novel treatment for acute vomiting in dogs. Vet Med 104: 422-423.
EMA (2009) Casopitant https://www.ema.europa.eu/en/documents/withdrawal-report/withdrawal-assessment report-zunrisa_en.pdf.
EMA (2021) Maropitant. https://www.ema.europa.eu/en/documents/scientific-discussion/cerenia-epar-scientific discussion_en.pdf.
FDA (2015) Rolapitant. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/206500s003,208399s002lbl.pdf.
Hill EF, Hoffman DJ (1984) Avian models for toxicity testing. J Am Coll Toxicol 3: 357-376.
Jelinek R (1982) Use of chick embryo in screening for embryotoxicity. Teratog Carcinog Mutagen 2: 255-261.
Jelinek R, Peterka M, Rychter Z (1985) Chick embryotoxicity screening test – 130 substances tested. Indian J Exp Biol 23: 588-595.
La Russo J, Waldman SA, Kraft WK (2008) Aprepitant for the prevention of nausea and vomiting associated with chemotherapy and postop-erative recovery. Expert Rev Clin Pharmacol 1: 27-37.
Ozparlak H (2015) The use of chick embryos in embryotoxi city and teratogenicity tests. SUFEFD 40: 13-22.
Singh V, Yadav Y, Solanki S (2021) Rolapitant: effects of an antiemetic agent on the growth of developing chick embryo. Int J Med Res Health Sci 10: 103-110.
Yazar E (2018) Veterinary drug and vaccine from A to Z, 1st ed., Nobel press, Istanbul, pp 153-154.
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Authors and Affiliations

M. Uslu
1
R. Canbar
2
G. Akcakavak
3
E. Yazar
1

  1. Department of Pharmacology and Toxicology, Veterinary Medicine, Selcuk University, 42130, Selcuklu, Konya, Turkey
  2. Department of Pharmacology and Toxicology, Veterinary Medicine, Necmettin Erbakan University, 42310, Eregli, Konya, Turkey
  3. Department of Pathology, Faculty of Veterinary Medicine, Yozgat Bozok University, 66900, Yozgat, Turkey
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Abstract

The study examines various approaches oriented towards conceptual and numerical reduction of first-principle models, data-driven methodologies for surrogate (black box) and hybrid (grey box) modeling, and addresses the prospect of using digital twins in chemical and process engineering. In the case of numerical reduction of mechanistic models, special attention is paid to methodologies in which simulation data are used to construct light but robust numerical models while preserving all the physics of the problem, yielding reduced-order datadriven but still white-box models. In addition to reviewing various methodologies and identifying their applications in chemical engineering, including industrial process engineering, as well as fundamental research, the study outlines associated problems and challenges, as well as the risks posed by the era of big data.
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Authors and Affiliations

Katarzyna Bizon
1
ORCID: ORCID

  1. Cracow University of Technology, Faculty of Chemical Engineering and Technology,Warszawska 24, 31-155 Kraków, Poland
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Abstract

The paper presents a plane model of articulated vehicles worked out for the analysis of their dynamics. The dAlambert principle was used for derivation of motion equations for this system. The forces and moments acting on wheels were formulated on the basis of the Dugoff-Uffelmann tyre model. The system consists of any number of vehicles connected by kinematic pair of the 5th class (non friction joint of pivot-bush type) and the fifth wheel (with dry fricton). Since crash calculations usually take into account the impulse of crash force only, and since it is not appropriate for articulated vehicles, a new approach to crash calculation is presented in this paper. The authors propose to calculate the force in crash point both as a function of the relative velocity of vehicles and the stiffness of their bodies. Simulation results of articulated lorry crashes and the attempt to verify the performed simulation are presented in the article.
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Authors and Affiliations

Witold Grzegożek
Piotr Świder
Andrzej Polański
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Abstract

The paper presents modelling proposal of the curvilinear scraper arm geometry by means of Bezier' s curve of the third degree. A physical model of scraping process of the unit load with the use of curvilinear arm for the most difficult sorting cases has been worked out. As a result of the performed numerical optimisation, there has been proposed the scraper arm shape geometry that makes it possible to decrease dynamic interaction exerted on the sorted loads.
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Authors and Affiliations

Tomasz Piątkowski
Janusz Sempruch
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Abstract

The paper presents a numerical model of car exhaust pollutant dispersion. The model can be used for estimation of the impact of pollutant emissions from road vehicles on the environment. The finite volume method has been used for model formulation. Equations obtained after discretisation are solved by using different methods like Runge-Kutta, Crank-Nicholson or decomposition methods. On the basis of the numerical simulation, conclusions are formulated about the numerical effectiveness of the integration methods used. In the paper, a problem of nitrogen oxides dispersion is formulated and solved, whereby chemical reactions are included in considerations. The model presented in the paper has been used for numerical calculations of car exhaust pollutant concentrations in a real car park. The last part of the paper presents some numerical results of calculations, which include emissions after cold start of engines.
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Authors and Affiliations

Krzysztof Brzozowski
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Abstract

The paper presents the numerical model of a supply vessel-load-crane-offshore vessel system for simulation of heave motion and dynamic analysis of the system during critical phases of the handling operation: taking the load off from and lowering it to a moving base. The model enables extreme forces in elements and deflection of the structure to be determined. Different operating and emergency conditions can be simulated (e.g. horizontal motion of a supply vessel). The elaborated software can be applied also for determination of derated load charts and ultimate crane capacity (sequence of failure).
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Authors and Affiliations

Marek Osiński
Andrzej Maczyński
Stanisław Wojciech
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Abstract

In model predictive control (MPC), methods of linear offset free MPC are well established such as the disturbance model, the observer method and the state disturbance observer method. However, the observer gain in those methods is difficult to define. Based on the drawbacks observed in those methods, a novel algorithm is proposed to guarantee offset-free MPC under model-plant mismatches and disturbances by combining the two proposed methods which are the proposed Recursive Kalman estimated state method and the proposed Disturbance-Kalman state method. A comparison is made from existing methods to assess the ability of providing offset-free MPC onWood-Berry distillation column. Results shows that the proposed offset free MPC algorithm has better disturbance rejection performance than the existing algorithms.
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Authors and Affiliations

Truong Thanh Tuan
1
Haslinda Zabiri
2
Mohammad Ibrahim Abdul Mutalib
2
Dai-Viet N. No
3

  1. Petrovietnam University, 762 Cach Mang Thang Tam Street, Long Toan Ward, Ba Ria City 78109, Ba Ria Vung Tau Province, Vietnam
  2. Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 32610 Tronoh, Perak, Malaysia
  3. Center of Excellence for Green Energy and Environmental Nanomaterials (CE@GrEEN), Nguyen Tat Thanh University, 300A Nguyen Tat Thanh, District 4, Ho Chi Minh City755414, Viet Nam

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