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Abstract

In this study, the potential of the substitution of the conventional preservative potassium sorbate by fermented wheat flour as an alternative was analysed. The organic acid content and antibacterial activity of preservatives and the macronutrient characterisation were tested, as was the sensory evaluation of biscuits with added conventional and alternative preservatives. The results show that the fermented wheat flour contains secondary fermentation metabolites (e.g. acetic, lactic and pyruvic acids). Both fermented wheat flour and potassium sorbate have antibacterial effects against Staphylococcus aureus, Bacillus cereus and Bacillus subtilis. The sensory evaluation demonstrated that fermented wheat flour in the recommended concentration range had no impact on sensory quality. Therefore, fermented wheat flour represents a potential substitution for conventional potassium in bakery products.

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Abstract

The efficiency of the most modern photovoltaic cells currently reaches 40–45%, which is achieved by concentrator systems. However, despite better device efficiencies concentrator photovoltaic cells have major drawback, namely the high amount of waste heat, which requires new cooling solutions.

This paper gives a short overview of the current cooling techniques and proposes a novel microchannel cooling solution for concentrator photovoltaic cells. In the concept, the microscale channels are integrated into the backside metallization of the PV device. The paper gives a description of the technological process that can be used to produce microchannels on the back of solar cells and shows the optimization of the channels to achieve optimal cooling performance.

Open access
Pollack Periodica
Authors: Gábor Rózsás, György Bognár, Gábor Takács, and Balázs Plesz

Abstract

The efficiency of the most modern photovoltaic cells currently reaches 40–45%, which is achieved by concentrator systems. However, despite better device efficiencies concentrator photovoltaic cells have major drawback, namely the high amount of waste heat, which requires new cooling solutions.

This paper gives a short overview of the current cooling techniques and proposes a novel microchannel cooling solution for concentrator photovoltaic cells. In the concept, the microscale channels are integrated into the backside metallization of the PV device. The paper gives a description of the technological process that can be used to produce microchannels on the back of solar cells and shows the optimization of the channels to achieve optimal cooling performance.

Open access
Pollack Periodica
Authors: Marek Šutúš, Jaroslav Hrudka, Gergély Rózsa, Ivona Škultétyová, and Štefan Stanko

Abstract

This research deals with creating a hydrodynamic combined sewerage overflow chamber model an ANSYS Workbench 19.2, Fluid Flow (Fluent). The 3D graphics model was created in the SpaceClaim modeling software, which serves as the basis for hydrodynamic modeling. The model was created according to a real combined sewerage overflow chamber in Banská Bystrica. The cores of the work are simulations that should correspond to the estimated flow in the combined sewerage overflow chamber. The aim of this paper is to compare the impact of inflow speed and flow rakes.

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Pollack Periodica
Authors: Marek Šutúš, Jaroslav Hrudka, Gergély Rózsa, Ivona Škultétyová, and Štefan Stanko

Abstract

This research deals with creating a hydrodynamic combined sewerage overflow chamber model an ANSYS Workbench 19.2, Fluid Flow (Fluent). The 3D graphics model was created in the SpaceClaim modeling software, which serves as the basis for hydrodynamic modeling. The model was created according to a real combined sewerage overflow chamber in Banská Bystrica. The cores of the work are simulations that should correspond to the estimated flow in the combined sewerage overflow chamber. The aim of this paper is to compare the impact of inflow speed and flow rakes.

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Abstract

Nowadays, digital technology and measurement are improving to measure some systems in accurate conditions without errors. From these improvements and developments, it is necessary to analyse performances and condition of bicycle and biker before high level computations. In this experimental investigation, a high quality and very light bicycle and a well-equipped trained biker were trained to test the system with different road and region conditions. The purpose of this investigation is to predict unwanted conditions of bicycle before computations and activity. Otherwise, this kind of experimental trained testing will give some information from unwanted bicycle accidents. Moreover, in this experimental work, a power meter and measurement instrument with sensors are used to measure real time parameters. As can be concluded from experimental results and the analysis, the proposed work has a good design and analysis for good material bicycles. The displacement analysis is also outlined with load of a 63 kg biker.

Open access

Abstract

Presence of pathogenic strains of Escherichia coli in foodstuffs may pose a health risk for a consumer. Therefore, knowledge on the effect of environmental factors on the growth ability of E. coli is of great importance. In this work, the effect of incubation temperature (6–46 °C) and the combined effect of temperature and water activity (0.991–0.930) on the growth dynamic of E. coli PSII were analysed. Based on the growth curves obtained, growth parameters were calculated by using the Baranyi D-model. Growth parameters were further analysed in secondary phase of predictive modelling. Using the CM model that describes the effect of combined factors, cardinal values (T min = 4.8 ± 0.4 °C, T opt = 41.1 ± 0.8 °C, T max = 48.3 ± 0.9 °C, a wmin = 0.932 ± 0.001, and a wopt = 0.997 ± 0.003) for the isolate were calculated. Under optimal conditions, the specific growth rate is µ opt = 2.84 ± 0.08 h−1. The results obtained may contribute to the assessment of the risk associated with the possible E. coli presence in raw materials and to the search for preventive measures with defined degree of accuracy and reliability.

Open access

Abstract

A numerical simulation procedure is presented to predict residual stress states in multi-pass welds in oil transportation pipes. In this paper, a two-dimensional thermo-mechanical finite element model is used to calculate the temperature distribution, hardness, and the distribution of residual stresses during multi-pass welding of pipes of dissimilar metals and varying thicknesses. In this model, the temperature dependence of the thermal and mechanical properties of the material was considered. The present model was validated using the hardness measurement. Good agreement was found between the measurement and the numerical simulation results. The simulated result shows that the two-dimensional model can be effectively used to simulate the hardness test and predict the residual stress in the pipe weld. The simulation results and measurements suggest that the model with moving heat source can obtain a good prediction of residual welding stress. Both the two-dimensional and the three-dimensional modeling can be used to estimate the residual stresses in different weld regions and help saving time.

Open access

Abstract

A numerical simulation procedure is presented to predict residual stress states in multi-pass welds in oil transportation pipes. In this paper, a two-dimensional thermo-mechanical finite element model is used to calculate the temperature distribution, hardness, and the distribution of residual stresses during multi-pass welding of pipes of dissimilar metals and varying thicknesses. In this model, the temperature dependence of the thermal and mechanical properties of the material was considered. The present model was validated using the hardness measurement. Good agreement was found between the measurement and the numerical simulation results. The simulated result shows that the two-dimensional model can be effectively used to simulate the hardness test and predict the residual stress in the pipe weld. The simulation results and measurements suggest that the model with moving heat source can obtain a good prediction of residual welding stress. Both the two-dimensional and the three-dimensional modeling can be used to estimate the residual stresses in different weld regions and help saving time.

Open access

Abstract

Energy storage on grid level is still a critical issue. Inventions related to development and control of smart buildings, including integrated solar systems can be easily realized by smart control of building management including storage. At buildings, which have high heat capacitance the part of the stored heat can be used for grid stabilization. This means the grid can be balanced with well-set up heating/cooling strategy and well-scheduled timetable via intelligent control of buildings. A possible solution is introduced in this paper, where the surplus production is used for overcooling the building, while the building thermodynamic properties are making it possible to store this amount of energy for days. This paper analyses a cost-effective solution of grid energy storage through a case study.

Open access