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Number of results: 78
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Abstract

This study is focused on the image analysis of motionless hydraulic mixing process, for which pressure changes were the driving force. To improve the understanding of hydraulic mixing, mixing efficiency was assessed with dye introduction, which resulted in certain challenges. In order to overcome them, the framework and methodology consisting of three main steps were proposed and applied to an experimental case study. The experiments were recorded using a camera and then processed according to the proposed framework and methodology. The main outputs from the methodology which were based only on the recorded movie were liquid heights and colour changes during the process time. In addition, considerable attention has also been given to issues related to other colour systems and the hydrodynamic description of the process.
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Authors and Affiliations

Aleksandra Golczak
1
Waldemar Szaferski
1
ORCID: ORCID
Szymon Woziwodzki
1
Piotr T. Mitkowski
1
ORCID: ORCID

  1. Poznan University of Technology, Department of Chemical Engineering and Equipment, Berdychowo 4, 60-965 Poznan, Poland
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Abstract

In this study, the phenomenon of mixing power increase when emptying tanks with an operating propeller impeller was examined. The tests were carried out for impellers with wide and narrow blades in two geometrically similar tanks with diameters T = 545 mm and T = 300 mm equipped with four standard baffles. The varied mixing power during tank emptying was examined on a larger scale, and on a scale of T = 300 mm the distribution of axial and radial velocities in the vertical r - z plane was determined using the PIV system. A very large increase in mixing power was found when the liquid-free surface being lowered was close to the upper surface of the blades. In the limit case, as much as a three-fold increase in mixing power was observed compared to the mixing power in a tank completely filled. It was found that the increase in mixing power was caused by a change in the mode of liquid circulation in the mixing tank when the liquid surface approached the impeller area. Correlation equations determining the values of the mixing power increase factor φ depending on the geometric parameters of the impeller and the Froude number are given. The φ values for propeller impellers were compared with similar values obtained for other types of impellers.
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Authors and Affiliations

Jacek Stelmach
1
ORCID: ORCID
Czesław Kuncewicz
1
ORCID: ORCID
Tomas Jirout
2
Frantisek Rieger
2

  1. Lodz University of Technology, Faculty of Process and Environmental Engineering, Wolczanska 213, 93-005 Lodz
  2. Czech Technical University in Prague, Faculty of Mechanical Engineering, Technicka 4, 166 04 Praha 6
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Abstract

Accordingly with the principles of the circular economy, mixed plastic wastes can be recycled also by thermoforming, getting new non-oriented fibers composite materials. This study highlights the mechanical behavior of new composite material plates containing recycled glass fibers as reinforcing element and ABS-PMMA mixture as matrix, as well as an efficient way to convert a manufacturing process wastes in a product. The mechanical behavior of new composite material plates was evidenced by tensile, flexural and compression tests. In addition a surface morphology analysis was performed.
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Authors and Affiliations

M.A. Platon
1
ORCID: ORCID
O. Nemeș
1 2
ORCID: ORCID
A.-E. Tiuc
1
ORCID: ORCID
C. Vilău
3
ORCID: ORCID
C.M. Dudescu
3
ORCID: ORCID
S. Pădurețu
4
ORCID: ORCID

  1. Technical University of Cluj-Napoca, Faculty of Materials and Environmental Engineering, 28 Memorandumului Street, 400114, Cluj-Napoca, Romania
  2. National Institute for Research and Development in Environmental Protection, 294 Blvd. Splaiul Independentei, Sector 6, 060031, Bucharest, Romania
  3. Technical University of Cluj-Napoca, Faculty of Automotive, Mechatronics and Mechanical Engineering, 28 Memorandumului Street, 400114, Cluj-Napoca, Romania
  4. Technical University of Cluj-Napoca, Faculty of Machine Building, 28 Memorandumului Street, 400114, Cluj-Napoca, Romania.
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Abstract

The future and development of energy is one of the most important problems in both domestic and global politics. Limiting the use of fossil fuels in the energy sector results from new legal conditions related to the protection of the natural environment. These changes require the development of a new energy strategy, taking the limits of greenhouse gas emissions in the European Union and the requirements of the Community energy policy into account. One of the documents affecting the structure of Poland’s energy mix is the Directive on renewable energy sources (2009/28/EC). Poland has committed to achieving the goal of a 15% share of energy from renewable sources (RES) in gross final energy consumption by 2020. Current changes in Polish RES support systems – in particular the transition from the system of green certificates to auctions for green energy – may threaten the achievement of the above-mentioned goal. The article analyzes whether Poland will meet renewable energy obligations by 2020 under the current conditions. In addition, the article presents current energy consumption in the world and in the country, legal conditions taken into account when creating the country’s energy mix and forecasts of renewable energy demand.

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Authors and Affiliations

Anna Manowska
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Abstract

In this study the formation of the polygenetic High Tatra granitoid magma is discussed. Felsic and mafic magma mixing and mingling processes occurred in all magma batches composing the pluton and are documented by the typical textural assemblages, which include: mafic microgranular enclaves (MME), mafic clots, felsic clots, quartz-plagioclase-titanite ocelli, biotite-quartz ocelli, poikilitic plagioclase crystals, chemically zoned K-feldspar phenocrysts with inclusion zones and calcic spikes in zoned plagioclase. Geochemical modelling indicates the predominance of the felsic component in subsequent magma batches, however, the mantle origin of the admixed magma input is suggested on the basis of geochemical and Rb-Sr, Sm-Nd and Pb isotopic data. Magma mixing is considered to be a first-order magmatic process, causing the magma diversification. The cumulate formation and the squeezing of remnant melt by filter pressing points to fractional crystallization acting as a second-order magmatic process.

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Authors and Affiliations

Aleksandra Gawęda
Krzysztof Szopa
Roman Włodyka
Jolanta Burda
Quentin Crowley
Magdalena Sikorska
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Abstract

Coal in Poland is an available conventional fuel providing energy security and independence of the country. Therefore, conventional energy generation should be based on coal with the optimal development of renewable energy sources. Such a solution secures the energy supply based on coal and the independence of political and economic turmoil of global markets. Polish coal reserves can secure the energy supply for decades. Coal will surely be important for energy security in the future despite the growing share of oil and gas in energy mix. The development of renewable power generation will be possible with the conventional energy generation offsetting volatile renewable power generation as Poland’s climate doesn’t allow for the stable and effective use of renewable energy sources. Considering the policy of the European Union with respect to emission reductions of greenhouse gasses and general trends as reflected in the Paris agreement in 2016, as a country we will be forced to increase renewable energy production in our energy mix. However, this process cannot impact the energy security of the country and stability and the uninterrupted supply of energy to consumers. Therefore seeking the compromise with the current energy mix in Poland is the best way to its gradual change with the simultaneous conservation of each of the sources of energy. It’s obvious that Poland can not be lonely energy island in Europe and in the world, which increasingly develops distributed energy and/ renewable technologies as well as energy storage ones. One can notice that without renewable generation and the reduction of coal’s share in country’s energy mix we will become the importer of electricity with raising energy dependence.

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Authors and Affiliations

Anna Kielerz
Waldemar Beuch
Robert Marzec
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Abstract

This paper presents the results of research on the admixture of other rock fragments in the granodiorite aggregate (two types of hornfels) produced in Łażany II quarry. It discusses the impact of these components on the selected chemical and mechanical properties important for the use of the aggregate in road construction. Analysed granodiorite grit is a high-class construction material suitable for bituminous mixtures. Its quality is verified in accordance with the PN-EN 13043 standard. The admixture of hornfels in aggregate composition is a consequence of the natural occuring this rock in the Łażany II granodiorite deposit in the Strzegom-Sobótka massif. As there is not selective exploitation of the deposit an extracted raw material is not separated during processing As a result, the aggregate, composed predominantly of granodiorite, comprises variable admixture of hornfels. Tests of properties, such as water absorption, resistance to freezing, resistance to fragmentation, crushing strength, carried out on grain populations of various petrographic types separated from the general samples, exhibit that the presence of hornfels in the aggregate has a beneficial effect, particularly on the mechanical parameters of the produced aggregate. Moreover, two varieties of hornfels differ in terms of some chemical properties (affinity with bitumen, presence of sulphides). These features may affect the durability of the aggregate in the wearing course which is directly influenced by the exterior conditions typical for road pavements.
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Authors and Affiliations

Bartłomiej Grzesik
1
ORCID: ORCID

  1. Silesian University of Technology, Gliwice, Poland
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Abstract

The progressive processes of globalization and changes in the global, European and local economy require integrated efforts aimed at solving problems related to development at the national regional and the local level involving the environment, energy sources, climate and technological transformation issues. European Union Member States are given right to create an individual Energy mix. Coal will continue to play a major role in Poland’s energy mix during the next decades. Polish coal reserves can provide energy security for decades.

Despite crude oil and natural gas growth in fuel consumption, coal will continue to be the stabilizer of energy security for the country and play an important role in Poland’s energy mix in the years to come. However, further coal consumption requires investments in low carbon technologies which are of high efficiency and in high-efficiency cogeneration.

The validity of the full utilization of cogeneration potential should be highlighted. Operating cogeneration plants are more expensive than power plants but they are more efficient and generate less carbon emissions. In accordance with the assumptions of the Energy policy of Poland, a low-carbon economy with renewable Energy sources and nuclear Energy should be supported and developed, however the obsolete coal generators should be replaced with low-carbon high-efficient ones.

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Authors and Affiliations

Anna Kielerz
Monika Porzerzyńska-Antonik
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Abstract

The research was conducted in a relatively small (26.8 ha) but quite deep (17.3 m) Lake Długie in Olsztyn, Poland. For over 20 years the lake was collecting sewage which eventually caused its complete degradation. In 1987-2000 the lake was restored using the artificial aeration method with destratification of water. The results showed that the artificial aeration effectively limited the internal loading. Application of this restoration method resulted in reduction of phosphorus compounds concentrations in the analyzed water strata. The decrease of TP in bottom sediments (to the level of 3-4 mg P g·' DW) was probably associated with the fact that a new layer of sediments was created, reflecting a change in the aquatic conditions caused by the restoration. The investigations conducted in the reference years showed that the changes were not permanent. A high concentration of phosphorus compounds in bottom sediments, low sorptivc capacity and a tendency to oxygen deficiency, indicate that further possibility to decrease the amount of phosphorus compounds in the lake by this restoration method is limited.
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Authors and Affiliations

Renata Brzozowska
Helena Gawrońska
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Abstract

The future and the development of power industry are the one of the major issues in the domestic and global policy. The impact of the power sector on the earth climate changes and the attention for sufficient funds of energy in the following years are the primary challenges which the power industry is facing. The article delineates the current state of the domestic sector of energy production. In the prospect of the next few years, it will draw on conventional power engineering nevertheless, with the growing involvement of renewable energy sources. However, it is important to develop the new energy strategy, which will point the direction of domestic energy production sector changes. What is more relevant, the new legal regulations connected with environmental protection will definitely restrict using fossil fuels in the power industry. In addition, the paper discusses the most important aspects involved in creating a country’s energy mix. The first aspect is the current state of the energy sector in Poland, i.e. the percentage of particular technologies in the present power and electrical energy balances, the technical state of the manufacturing sector’s infrastructure. Based on historical data of Polskie Sieci Elektroenergetyczne SA regarding the energy consumption and demand, a mathematical estimation for electricity demand and its consumption forecast was performed. The obtained forecasts were then used to conduct a simulation of power and energy demand fulfillment in the national power system. Finally, several possible scenarios were presented, taking different factors affecting the energy sector in Poland into consideration.

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Authors and Affiliations

Radosław Szczerbowski
Dominika Kornobis
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Abstract

Obtaining a pure product by mixing together raw materials, so as to carry out a chemical reaction at high selectivity, is a difficult part of manufacturing chemical products. How can we test reactors and mixers to ensure the efficient use of energy?

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Authors and Affiliations

Magdalena Jasińska
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Abstract

The paper presents the results of research and analysis of the effect of joining by the RFSSW method of alclad sheets made of Al2024 with an anodic oxide coating, with the using the tool with modified geometry of the front surface of inner sleeve. The different effects of the modifications made on the phenomenon of plasticization and stirring of materials in the process of creating a weld, microstructure of welds and mechanical strength of lap joints were shown. The tests were carried out on 1.27 mm thick sheets, with the use of an unmodified tool and modified tools with three variants of the geometry. The welds and the joints samples were subjected to metallographic and strength tests. It has been shown that the use of a properly selected modified geometry has a beneficial effect on the transport of materials to be joined in the joint zone (flow pattern of plasticized layers and the stirring effect) during the welding, which translates into the strength of the joints and the nature of the weld failure.
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Authors and Affiliations

W. Łogin
1
ORCID: ORCID
R.E. Śliwa
2
ORCID: ORCID
R. Ostrowski
2
ORCID: ORCID

  1. Development Project Office, Polskie Zakłady Lotnicze w Mielcu Sp. z o.o., Poland
  2. Rzeszów University of Technology, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland
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Abstract

Small bucket models with many short fictitious micro-periods ensure high-quality schedules in multi-level systems, i.e., with multiple stages or dependent demand. In such models, setup times longer than a single period are, however, more likely. This paper presents new mixedinteger programming models for the proportional lot-sizing and scheduling problem (PLSP) with setup operations overlapping multiple periods with variable capacity.
A new model is proposed that explicitly determines periods overlapped by each setup operation and the time spent on setup execution during each period. The model assumes that most periods have the same length; however, a few of them are shorter, and the time interval determined by two consecutive shorter periods is always longer than a single setup operation. The computational experiments showthat the newmodel requires a significantly smaller computation effort than known models.
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Bibliography

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[2] G. Belvaux and L.A. Wolsey: Modelling practical lot-sizing problems as mixed-integer programs. Management Science, 47(7), (2001), 993–1007, DOI: 10.1287/mnsc.47.7.993.9800.
[3] J.D. Blocher, S. Chand and K. Sengupta: The changeover scheduling problem with time and cost considerations: Analytical results and a forward algorithm. Operations Research, 47(7), (1999), 559-569, DOI: 10.1287/opre.47.4.559.
[4] W. Bozejko, M. Uchronski and M. Wodecki: Multi-machine scheduling problem with setup times. Archives of Control Sciences, 22(4), (2012), 441– 449, DOI: 10.2478/v10170-011-0034-y.
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[7] K. Copil, M. Worbelauer, H. Meyr and H. Tempelmeier: Simultaneous lotsizing and scheduling problems: a classification and review of models. OR Spectrum, 39(1), (2017), 1–64, DOI: 10.1007/s00291-015-0429-4.
[8] A. Drexl and K. Haase: Proportional lotsizing and scheduling. International Journal of Production Economics, 40(1), (1995), 73–87, DOI: 10.1016/0925-5273(95)00040-U.
[9] B. Fleischmann: The discrete lot-sizing and scheduling problem. European Journal of Operational Research, 44(3), (1990), 337-348, DOI: 10.1016/0377-2217(90)90245-7.
[10] K. Haase: Lotsizing and scheduling for production planning. Number 408 in Lecture Notes in Economics and Mathematical Systems. Springer-Verlag, Berlin, 1994.
[11] W. Kaczmarczyk: Inventory cost settings in small bucket lot-sizing and scheduling models. In Total Logistic Management Conference, Zakopane, Poland, November 25-28 2009.
[12] W. Kaczmarczyk: Modelling multi-period set-up times in the proportional lot-sizing problem. Decision Making in Manufacturing and Services, 3(1-2), (2009), 15–35, DOI: 10.7494/dmms.2009.3.2.15.
[13] W. Kaczmarczyk: Proportional lot-sizing and scheduling problem with identical parallel machines. International Journal of Production Research, 49(9), (2011), 2605–2623, DOI: 10.1080/00207543.2010.532929.
[14] W. Kaczmarczyk: Valid inequalities for proportional lot-sizing and scheduling problem with fictitious microperiods. International Journal of Production Economics, 219(1), (2020), 236–247, DOI: 10.1016/j.ijpe.2019.06.005.
[15] W.Kaczmarczyk: Explicit modelling of multi-period setup times in proportional lot-sizing problem with constant capacity. (2021), Preprint available at Research Square, DOI: 10.21203/rs.3.rs-1086310/v1.
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Authors and Affiliations

Waldemar Kaczmarczyk
1
ORCID: ORCID

  1. Department of Strategic Management, AGH University of Science and Technology, Al.Mickiewicza 30, 30-059, Kraków, Poland
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Abstract

Most algorithms for the economic lot scheduling problem (elsp) following the extended basic period approach consist of two decision levels. On the upper level, the length of the production cycle and the number of lots (frequency) within the cycle for all products are determined. On the lower level, lots are scheduled to level workloads of all periods and ensure a timely start of production. This paper presents a new mixed-integer programming (mip) model for the scheduling subproblem under the power-of-two policy. This is the first mip model that exactly determines and minimizes additional inventory holding costs due some lots’ premature start of production. It may be solved by a free general-purpose solver within a fraction of a second. Experiments with several problem instances described in the literature confirmed that using the new model within a heuristic algorithm ensures a significant cost reduction for the entire elsp. Additionally, all optimal schedules for the Bomberger case are presented.
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Authors and Affiliations

Waldemar Kaczmarczyk
1
ORCID: ORCID

  1. Faculty of Management, AGH University, al. Mickiewicza 30, 30-059, Kraków, Poland
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Abstract

The leakage of natural gas pipelines will waste energy and damage the environment. Research on the leakage and diffusion features of hydrogen-doped natural gas is beneficial to the safe management of natural gas pipelines. This paper established a numerical model used for simulating and computing the diffusion of hydrogen-doped natural gas. Then, simulation experi-ments were conducted. First, the model accuracy was verified through experiments, and the appropriate mesh number of the model was determined. Then, the influence of different hydrogen blending ratios and various leakage hole diameters on the leakage and diffusion of gas was calculated. Under the same diffusion time, the higher the hydrogen content in the gas, the higher the diffusion rate of methane and hydrogen, and the diffusion rate of hydrogen had the most obvious change. Under the same diffusion time, the closer to the leakage hole, the higher the concentration of natural gas, and the concentration at the monitoring points at the same level differed little.
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Authors and Affiliations

Xiang Zhou
1
Dewen Kong
1
Teng Ren
2

  1. Jiangsu Vocational College of Information Technology, No. 1 Qianou Road, Huishan District, Wuxi City, Jiangsu 214153, China
  2. Shenyang University of Technology, Shenyang, Liaoning 110023, China
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Abstract

This study presents the results of tests on the mixing power and distribution of three velocity components in the mixing tank for an FBT impeller during tank emptying with an operating impeller. A laser PIV system was used to determine speed distributions. It was found that for the relative liquid height in the tank H* = H/H0 ≈ 0.65 and H* ≈ 0.45, the liquid circulation in the impeller zone changed from radial to axial and vice versa. These changes were accompanied by changes in the mixing power which even reached 40%. In the theoretical part, a method of calculating the mixing power using the classical model of the central vortex and distribution of the tangential speed in the impeller zone was proposed. Although the method turned out to be inaccurate, it was useful for determining the relative power.
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Authors and Affiliations

Jacek Stelmach
1
ORCID: ORCID
Czesław Kuncewicz
1
ORCID: ORCID
Tomáš Jirout
2
ORCID: ORCID
František Rieger
2
ORCID: ORCID

  1. Lodz University of Technology, Faculty of Process and Environmental Engineering, Wólczańska 213, 93-005 Łódź
  2. Czech Technical University in Prague, Faculty of Mechanical Engineering, Technická 4, 166 07 Praha 6
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Abstract

The present work comprises a numerical analysis using the Ansys program to solve the problem of combined free-forced convection around a circular cylinder located in a horizontal lid-driven trapezoidal enclosure. The enclosure is filled with water. The upper moving wall and lower fixed wall are cold at a constant temperature, whereas the inclined walls are adiabatically insulated. The uniformly heated cylinder is located at different positions in the cavity. The study covers three values of Richardson number (0.01, 1, and 10). The results show that the streamlines and isotherms in the enclosure, the Nusselt number and friction factor in the moving wall, hot wall and bottom wall are strongly dependent on the position of the inner hot cylinder. The results are validated with previous work, and the comparison gives good agreement.
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Authors and Affiliations

Asmaa Ali Hussein
1

  1. Middle Technical University, Institute of Technology/Baghdad, Baghdad, Iraq
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Abstract

The production of ethyl oleate, by homogenous acid esterification of oleic acid with ethanol, have discussed experimentally and via computational simulation in a plug flow reactor. An innovative simulation model has developed to predict the esterification reaction performance in an ideal plug flow reactor. The amount of H2SO4 acid catalyst, the initial molar ratio of alcohol to oleic acid, ethanol concentration, reaction temperature, and esterification time have examined their effects on ethyl oleate production and the conversion of oleic acid. Then the simulation extended to examine the esterification reaction kinetics and determine the reaction rate coefficients. The simulation results demonstrate that the increasing of H2SO4 acid, initial molar ratio of ethanol to oleic acid, ethanol concentration, and reaction temperature improved the productivity of the ethyl oleate and reduced the reactor space-time. The kinetics results illustrated that the reaction sensitivity to the temperature unchanging by using higher ethanol concentration and alcohol to oleic acid initial ratio. Lastly, the experimental yields at different conditions were slightly higher from those simulating with average values of 93.62 and 92.29%, respectively, indicating that the phenomenon of back-mixing cannot be ignored in esterification reactors, especially with a relatively high retention time within the reactor.
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Authors and Affiliations

Suondos K.A. Barno
1
Sarmad A. Rashid
2
Ammar S. Abbas
2

  1. Presidency of the University of Baghdad, Baghdad, Iraq
  2. Chemical Engineering Department, College of Engineering, University of Baghdad, Baghdad, Iraq
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Abstract

The current trend in the preparation of green sand mixtures emphasizes the acceleration of the mixing process while maintaining the quality of the mixture. This requirement results in the necessity of determining the optimal conditions for mixing the mixture with a given mixer. This work aims to determine the optimal mixing conditions for the newly introduced eddy mixer LM-3e from the company Multiserw-Morek in the sand laboratory at the Department of Metallurgical Technologies, Faculty of Materials and Technology, VŠB - Technical University of Ostrava. The main monitored properties of mixtures will be green compressive strength and moisture of the mixture. The measured properties of the mixture mixed on the eddy mixer will be compared with the properties of the mixture mixed on the existing LM-2e wheel mixer. The result of the experiment confirmed that the eddy mixer is suitable for the preparation of a mixture of the same quality as the wheel mixer but with a significantly reduced mixing time.
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Bibliography

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Authors and Affiliations

Š. Kielar
1
M. Bašistová
1
ORCID: ORCID
P. Lichy
1
ORCID: ORCID

  1. VSB - Technical University of Ostrava Faculty of Materials Science and Technology, Czech Republic
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Abstract

We demonstrate in this study that a rotating magnetic field (RMF) and spinning magnetic particles using this kind of magnetic field give rise to a motion mechanism capable of triggering mixing effect in liquids. In this experimental work two mixing mechanisms were used, magnetohydrodynamics due to the Lorentz force and mixing due to magnetic particles under the action of RMF, acted upon by the Kelvin force. To evidence these mechanisms,we report mixing time measured during the neutralization process (weak acid-strong base) under the action of RMF with and without magnetic particles. The efficiency of the mixing process was enhanced by a maximum of 6.5% and 12.8% owing to the application of RMF and the synergistic effect of magnetic field and magnetic particles, respectively.
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Authors and Affiliations

Rafał Rakoczy
1
ORCID: ORCID
Marian Kordas
1
ORCID: ORCID
Agata Markowska-Szczupak
1
ORCID: ORCID
Maciej Konopacki
1
ORCID: ORCID
Adrian Augustyniak
1
ORCID: ORCID
Joanna Jabłońska
1
Oliwia Paszkiewicz
1
ORCID: ORCID
Kamila Dubrowska
1
Grzegorz Story
1
Anna Story
1
Katarzyna Ziętarska
1
Dawid Sołoducha
1
Tomasz Borowski
1
Marta Roszak
2
Bartłomiej Grygorcewicz
2
ORCID: ORCID
Barbara Dołęgowska
2
ORCID: ORCID

  1. West Pomeranian University of Technology in Szczecin, Faculty of Chemical Technology and Engineering, Department of Chemical and Process Engineering, al. Piastów 42,71-065 Szczecin, Poland
  2. Pomeranian Medical University in Szczecin, Chair of Microbiology, Immunology and Laboratory Medicine, Department of Laboratory Medicine, al. Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland
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Abstract

A statistical approach was conducted to investigate effect of independent factors of the mixing time compactability and bentonite percentage on dependent variables of permeability, compression and tensile strength of sand mould properties. Using statistical method save time in estimating the dependent variables that affect the moulding properties of green sand and the optimal levels of each factor that produce the desired results.
The results yielded indicate that there are variations in the effects of these factors and their interactions on different properties of green sand. The outcomes obtained a range of permeability values, with the highest and lowest numbers being 125 and 84. The sand exhibited high values of tensile and compressive strength measuring at 0.33N/cm2 and 17.67N/cm2. Conversely it demonstrated low levels of tensile and compressive strength reaching 0.14N/cm2 and 9.32N/cm2.
These results suggest that the moulding factors and their interactions have an important role in determining properties of the green sand. ANOVA was used to assess effect of various factors on different properties of the green sand. The results obtained suggest that compactability factor play a significant effect on permeability, the mixing time or bentonite factor has a significant effect on the compressive strength and mixing time or compactability factor has a significant impact on the tensile strength with a significance level lower than 5%. It is found that neither the mixing time nor the amount of bentonite used in the green sand mix has a significant impact on its permeability. Compactability of the green sand does not has a significant effect on the compressive strength. Bentonite used in green sand mix does not have a significant impact on its tensile strength.
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Authors and Affiliations

Dheya Abdulamer
1
ORCID: ORCID

  1. University of Technology, Iraq
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Abstract

The article presents the results of a sociolinguistic study of surzhyk in the speech of residents of the North‑Eastern region of Ukraine. The focus is on the main trends of communicative possibilities of surzhyk and its functional features in the situation of a multi‑code. It was found that the conscious use of surzhyk speech is a characteristic primarily of young speakers, who are able to realise its irregularity and use for a certain purpose, although in a limited range of situations. In situations of family communication, they use surzhyk as their ‘home language’. Such behaviour can also be a sign of a certain communicative ‘game’ when the speaker uses any language ‘image’ adapted to the specific needs of language communication. A diachronic analysis of the functional capabilities of surzhyk made it possible to reveal, on the one hand, its gradual ‘ageing’ as a functional first language, and on the other hand, its ‘getting younger’ as a conventional stylistic marker. Besides, its increased frequency in extra‑family communication has been recorded, which may indicate a gradual transition of the Russian‑speaking residents of Sumy to Ukrainian‑speaking forms of behaviour.
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Authors and Affiliations

Tetiana Kuznietsova
1 2

  1. Ольденбург, Інститут славістики Університету ім. Карла фон Осецького
  2. Київ, Київський університет імені Бориса Грінченка
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Abstract

The beginning of the COVID-19 pandemic brought about a sudden and significant change in the conditions of various academic activities. In the present study, we wanted to investigate the influence of the first pandemic lockdown on procrastination tendencies among Polish students. To achieve this goal we employed a mixed-method, embedded longitudinal study. In the quantitative part of the research, the same group of university students completed the procrastination questionnaire twice: a year before, and two months after the introduction of the first pandemic lockdown. The qualitative part included the open-ended questions about the perceived reasons for an observed change in a tendency to postpone tasks after the pandemic outbreak. Our analyses showed a significant increase in academic procrastination after the lockdown introduction. In particular, students reported a decrease in the study interest and lower working discipline. As the causes of higher procrastination during the lockdown period, students most frequently pointed out the reduced monitoring of work progress by supervisors and lower negative consequences of delaying tasks. The second most frequent theme in provided answers included difficulty in restraining from alternative activities and problems with focusing on tasks or ignoring distractions. Embedding qualitative and quantitative data gave a consistent picture of students' situation in the first lockdown and provided potential explanation for the exacerbation of procrastinatory behaviors after the pandemic outbreak.
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Authors and Affiliations

Marcel Kawczyński
2
ORCID: ORCID
Ewa Wiwatowska
1
ORCID: ORCID
Jarosław Michałowski
1
ORCID: ORCID

  1. SWPS University of Social Sciences and Humanities, Poznań, Poland
  2. Adam Mickiewicz University, Poznań, Poland
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Abstract

To meet the requirements of the image processing process on image quality, as the ore image contains Gaussian noise, pepper noise, Rayleigh noise, and other kinds of mixed noise is easy to destroy the real information of the image combined with the advantages of wavelet and non-local mean filtering, a new wavelet + non-local mean (NL-means) fusion denoising algorithm is proposed. Taking the ore image with mixed noise obtained from a mine as the research object, the wavelet function is used to carry out a two-dimensional wavelet transform on the filled image, separating the high and low-frequency information, setting the threshold vector to deal with the high-frequency wavelet coefficients, inverting the transform to get the first reconstructed image, followed by the second inverse transform. Then, the second reconstructed image is subjected to NL-mean denoising to remove the complex mixed noise in the ore image to the maximum extent. The experimental results show that the noise reduction performance of the fusion denoising algorithm has a greater improvement compared with the single filter and several other fusion algorithms. The peak signal-to-noise ratio of the denoised image is 31.0181dB. The structural similarity is 0.59913, which is 15.7584dB and 0.45241, respectively, compared with that before denoising. It has an obvious effect on the removal of the mixed noise in the ore image, which provides strong technical support to improve the noise removal of the ore image.
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Authors and Affiliations

Zhi Hong Jiang
1
Ao Chen
1
ORCID: ORCID
Wen Cong Xiao
1
Jin Ruo Huang
1

  1. Jiangxi University of Science and Technology, Faculty of Mechatronic Engineering, China

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