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Energies, Volume 14, Issue 24 (December-2 2021) – 412 articles

Cover Story (view full-size image): Numerical simulation of multiple components in turbomachinery applications is very CPU demanding but remains necessary to capture the proper coupling and a reliable flow prediction in most cases. The use of realistic boundary conditions capable of accurately reproducing this coupling between components at a lower cost is of great interest. This paper presents a method able to generate more realistic boundary conditions for isolated turbine Large-Eddy Simulation (LES). The unsteady boundary conditions to be used at the inflow of the isolated turbine LES are built from the modal decomposition of the database recorded at the interface between the two components of the integrated LES simulation. The results demonstrate the capacity of this type of conditions to reproduce the coupling between the combustion chamber and the turbine when standard conditions cannot.View this paper
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Article
Energy Storage Economic Optimization Scheduling Method for Multi-Scene Demand of Peak and Frequency Modulation
Energies 2021, 14(24), 8605; https://doi.org/10.3390/en14248605 - 20 Dec 2021
Viewed by 387
Abstract
Energy storage (ES) only contributes to a single-scene (peak or frequency modulation (FM)) control of the power grid, resulting in low utilization rate and high economic cost. Herein, a coordinated control method of peak modulation and FM based on the state of ES [...] Read more.
Energy storage (ES) only contributes to a single-scene (peak or frequency modulation (FM)) control of the power grid, resulting in low utilization rate and high economic cost. Herein, a coordinated control method of peak modulation and FM based on the state of ES under different time scales is proposed. Firstly, for monotone peak and FM control scenarios, the ES configuration and scheduling model is constructed with the goal of maximizing net profit. Secondly, to further improve the ES utilization rate and optimize the operating cost of ES, a cooperative control method of peak modulation and FM is proposed. This method can realize the switch between peak modulation and FM control of ES and improve the ES utilization rate and system economy. Finally, the simulation results show that, compared with that of mono-peak and single-FM control, the ES efficiency of the peak-FM multiscenario optimization scheduling method is improved by 16.25% and 37.29%, respectively. The annual net income is increased by €28,021.50, the investment recovery period is shortened by 0.27 years, and the ES configuration economy is effectively improved. Full article
(This article belongs to the Special Issue Frontier in Special Power Conversion Systems and Control)
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Article
Influence of Injection Well Location on CO2 Geological Storage Efficiency
Energies 2021, 14(24), 8604; https://doi.org/10.3390/en14248604 - 20 Dec 2021
Viewed by 347
Abstract
An analysis of the influence of injection well location on CO2 storage efficiency was carried out for three well-known geological structures (traps) in deep aquifers of the Lower Jurassic Polish Lowlands. Geological models of the structures were used to simulate CO2 [...] Read more.
An analysis of the influence of injection well location on CO2 storage efficiency was carried out for three well-known geological structures (traps) in deep aquifers of the Lower Jurassic Polish Lowlands. Geological models of the structures were used to simulate CO2 injection at fifty different injection well locations. A computer simulation showed that the dynamic CO2 storage capacity varies depending on the injection well location. It was found that the CO2 storage efficiency for structures with good reservoir properties increases with increasing distance of the injection well from the top of the structure and with increasing depth difference to the top of the structure. The opposite is true for a structure with poor reservoir properties. As the quality of the petrophysical reservoir parameters (porosity and permeability) improves, the location of the injection well becomes more important when assessing the CO2 storage efficiency. Maps of dynamic CO2 storage capacity and CO2 storage efficiency are interesting tools to determine the best location of a carbon dioxide injection well in terms of gas storage capacity. Full article
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Article
Simulation and Techno-Economic Analysis of a Power-to-Hydrogen Process for Oxyfuel Glass Melting
Energies 2021, 14(24), 8603; https://doi.org/10.3390/en14248603 - 20 Dec 2021
Viewed by 436
Abstract
As an energy-intensive industry sector, the glass industry is strongly affected by the increasingly stringent climate protection targets. As established combustion-based production systems ensure high process stability and glass quality, an immediate switch to low greenhouse gas emission processes is difficult. To approach [...] Read more.
As an energy-intensive industry sector, the glass industry is strongly affected by the increasingly stringent climate protection targets. As established combustion-based production systems ensure high process stability and glass quality, an immediate switch to low greenhouse gas emission processes is difficult. To approach these challenges, this work investigates a step-by-step integration of a Power-to-Hydrogen concept into established oxyfuel glass melting processes using a simulation approach. This is complemented by a case study for economic analysis on a selected German glass industry site by simulating the power production of a nearby renewable energy park and subsequent optimization of the power-to-hydrogen plant performance and capacities. The results of this study indicate, that the proposed system can reduce specific carbon dioxide emissions by up to 60%, while increasing specific energy demand by a maximum of 25%. Investigations of the impact of altered combustion and furnace properties like adiabatic flame temperature (+25 °C), temperature efficiency (Δξ = −0.003) and heat capacity flow ratio (ΔzHL = −0.009) as a function of H2 content in the fuel mixture and resulting furnace efficiencyindicate that pure hydrogen-oxygen combustion has less impact on melting properties than assumed so far. Within the case study, high CO2 abatement costs of 295 €/t CO2-eq. were determined. This is mainly due to the insufficient performance of renewable energy sources. The correlations between process scaling and economic parameters presented in this study show promising potential for further economic optimization of the proposed energy system in the future. Full article
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Article
The Method to Determine the Turns Ratio Correction of the Inductive Current Transformer
Energies 2021, 14(24), 8602; https://doi.org/10.3390/en14248602 - 20 Dec 2021
Viewed by 251
Abstract
This paper presents the method for evaluation of the turns ratio correction of the inductive current transformer using the magnetization curves determined at the non-load state and in the load conditions. The presented method may be applied to determine even a fractional winding [...] Read more.
This paper presents the method for evaluation of the turns ratio correction of the inductive current transformer using the magnetization curves determined at the non-load state and in the load conditions. The presented method may be applied to determine even a fractional winding correction factor. The standard IEC 61869-2 provides the method to determine the turns ratio correction of the tested CT from the measured rms values of voltages on its primary and secondary winding in the non-load state. However, this approach is limited in determining the significant changes in the number of turns of the secondary winding. Moreover, the paper presents the influence of the applied turns ratio correction on the frequency characteristics of the current error and phase displacement of the inductive current transformers evaluated for the transformation of the distorted current. Full article
(This article belongs to the Special Issue Development of Voltage and Current Transformers in Power System)
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Article
Intelligent Service Selection in a Multi-Dimensional Environment of Cloud Providers for Internet of Things Stream Data through Cloudlets
Energies 2021, 14(24), 8601; https://doi.org/10.3390/en14248601 - 20 Dec 2021
Viewed by 352
Abstract
The expansion of Internet of Things (IoT) services and the huge amount of data generated by different sensors signify the importance of cloud computing services such as Storage as a Service more than ever. IoT traffic imposes such extra constraints on the cloud [...] Read more.
The expansion of Internet of Things (IoT) services and the huge amount of data generated by different sensors signify the importance of cloud computing services such as Storage as a Service more than ever. IoT traffic imposes such extra constraints on the cloud storage service as sensor data preprocessing capability and load-balancing between data centers and servers in each data center. Furthermore, service allocation should be allegiant to the quality of service (QoS). In the current work, an algorithm is proposed that addresses the QoS in storage service allocation. The proposed hybrid multi-objective water cycle and grey wolf optimizer (MWG) considers different QoS objectives (e.g., energy, processing time, transmission time, and load balancing) in both the fog and cloud Layers, which were not addressed altogether. The MATLAB script is used to simulate and implement our algorithms, and services of different servers, e.g., Amazon, Dropbox, Google Drive, etc., are considered. The MWG has 7%, 13%, and 25% improvement, respectively, in comparison with multi-objective water cycle algorithm (MOWCA), k-means based GA (KGA), and non-dominated sorting genetic algorithm (NSGAII) in metric of spacing. Moreover, the MWG has 4%, 4.7%, and 7.3% optimization in metric of quality in comparison to MOWCA, KGA, and NSGAII, respectively. The new hybrid algorithm, MWG, not only yielded to the consideration of three objectives in service selection but also improved the performance compared to the works that considered one or two objective(s). The overall optimization shows that the MWG algorithm has 7.8%, 17%, and 21.6% better performance than MOWCA, KGA, and NSGAII in the obtained best result by considering different objectives, respectively. Full article
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Article
Blockchain-Enabled Energy Demand Side Management Cap and Trade Model
Energies 2021, 14(24), 8600; https://doi.org/10.3390/en14248600 - 20 Dec 2021
Viewed by 373
Abstract
Global economic growth, demographic explosion, digitization, increased mobility, and greater demand for heating and cooling due to climate change in different world areas are the main drivers for the surge in energy demand. The increase in energy demand is the basis of economic [...] Read more.
Global economic growth, demographic explosion, digitization, increased mobility, and greater demand for heating and cooling due to climate change in different world areas are the main drivers for the surge in energy demand. The increase in energy demand is the basis of economic challenges for power companies alongside several socio-economic problems in communities, such as energy poverty, defined as the insufficient coverage of energy needs, especially in the residential sector. Two main strategies are considered to meet this increased demand. The first strategy focuses on new sustainable and eco-friendly modes of power generation, such as renewable energy resources and distributed energy resources. The second strategy is demand-side oriented rather than the supply side. Demand-side management, demand response (DR), and energy efficiency (EE) programs fall under this category. On the other hand, the decentralization and digitization of the energy sector convoyed by the emersion of new technologies such as blockchain, Internet of Things (IoT), and Artificial Intelligence (AI), opened the door to new solutions for the energy demand dilemma. Among these technologies, blockchain has proved itself as a decentralized trading platform between untrusted peers without the involvement of a trusted third party. This newly introduced Peer-to-Peer (P2P) trading model can be used to create a new demand load control model. In this article, the concept of an energy cap and trade demand-side management (DSM) model is introduced and simulated. The introduced DSM model is based on the concept of capping consumers’ monthly energy consumption and rewarding consumers who do not exceed this cap with energy tradeable credits that can be traded using blockchain-based Peer-to-Peer (P2P) energy trading. A model based on 200 households is used to simulate the proposed DSM model and prove that this model can be beneficial to both energy companies and consumers. Full article
(This article belongs to the Special Issue Smart Energy Management for Smart Grid)
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Article
Combined NOx and NH3 Slip Reduction in a Stoker Boiler Equipped with the Hybrid SNCR + SCR System FJBS+
Energies 2021, 14(24), 8599; https://doi.org/10.3390/en14248599 - 20 Dec 2021
Viewed by 229
Abstract
The application of secondary NOx control methods in medium to low-capacity furnaces is a relatively new topic on the energy market and thus requires further research. In this paper, the results of full-scale research of SNCR and hybrid SNCR + SCR methods [...] Read more.
The application of secondary NOx control methods in medium to low-capacity furnaces is a relatively new topic on the energy market and thus requires further research. In this paper, the results of full-scale research of SNCR and hybrid SNCR + SCR methods applied into a 29 MWth solid fuel fired stoker boiler is presented. The tests were performed for a full range of boiler loads, from 33% (12 MWth) to 103% (30 MWth) of nominal load. A novel SNCR + SCR hybrid process was demonstrated based on an enhanced in-furnace SNCR installation coupled with TiO2-WO3-V2O5 catalyst, which provides extra NOx reduction and works as an excess NH3 “catcher” as well. The performance of a brand-new catalyst was evaluated in comparison to a recovered one. The emission of NOx was reduced below 180 mg NOx/Nm3 at 6% O2, with ammonia slip in flue gas below 10 mg/Nm3. Special attention was paid to the analysis of ammonia slip in combustion products: flue gas and fly ash. An innovative and cost-effective method of ammonia removal from fly ash was presented and tested. The main idea of this method is fly ash recirculation onto the grate. As a result, ammonia content in fly ash was reduced to a level below 6.1 mg/kg. Full article
(This article belongs to the Special Issue Computational Thermal, Energy, and Environmental Engineering)
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Article
Numerical Modelling of Various Aspects of Pipe Pile Static Load Test
Energies 2021, 14(24), 8598; https://doi.org/10.3390/en14248598 - 20 Dec 2021
Viewed by 237
Abstract
Due to the development of dedicated software and the computing capabilities of modern computers, the application of numerical methods to analyse more complex geotechnical problems is becoming increasingly common. However, there are still some areas which, due to the lack of unambiguous solutions, [...] Read more.
Due to the development of dedicated software and the computing capabilities of modern computers, the application of numerical methods to analyse more complex geotechnical problems is becoming increasingly common. However, there are still some areas which, due to the lack of unambiguous solutions, require a more thorough examination, e.g., the numerical simulations of displacement pile behaviour in soil. Difficulties in obtaining the convergence of simulations with the results of static load tests are mainly caused by problems with proper modelling of the pile installation process. Based on the numerical models developed so far, a new process of static load test modelling has been proposed, which includes the influence of pile installation on the soil in its vicinity and modelling of contact between steel pile and the soil. Although the presented method is not new, this is relevant and important for practitioners that may want to improve the design of displacement piles. The results of the numerical calculations were verified by comparing them with the results of pipe pile field tests carried out in a natural scale on the test field in Southern Poland. Full article
(This article belongs to the Special Issue Sustainable Geotechnical Engineering and Its Applications)
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Article
Forecasting of Natural Gas Consumption in Poland Based on ARIMA-LSTM Hybrid Model
Energies 2021, 14(24), 8597; https://doi.org/10.3390/en14248597 - 20 Dec 2021
Viewed by 213
Abstract
Natural gas is one of the main energy sources in Poland and accounts for about 15% of the primary energy consumed in the country. Poland covers only 1/5 of its demand from domestic deposits. The rest is imported from Russia, Germany, Norway, the [...] Read more.
Natural gas is one of the main energy sources in Poland and accounts for about 15% of the primary energy consumed in the country. Poland covers only 1/5 of its demand from domestic deposits. The rest is imported from Russia, Germany, Norway, the Czech Republic, Ukraine, and Central Asia. An important issue concerning the market of energy resources is the question of the direct impact of the prices of energy resources on the income of exporting and importing countries. It should also be remembered that unexpected and large fluctuations are detrimental to both exporters and importers of primary fuels. The article analyzes natural gas deposits in Poland, raw material trade and proposes a model for forecasting the volume of its consumption, which takes into account historical consumption, prices of energy resources and assumptions of Poland’s energy policy until 2040. A hybrid model was built by combining ARIMA with LSTM artificial neural networks. The validity of the constructed model was assessed using ME, MAE, RMSE and MSE. The average percentage error is 2%, which means that the model largely represents the real gas consumption course. The obtained forecasts indicate an increase in consumption by 2040. Full article
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Article
Non-Dimensional Analysis of Diffusion Characteristics in Polymer Electrolyte Membrane Fuel Cells with Mismatched Anodic and Cathodic Flow Channels
Energies 2021, 14(24), 8596; https://doi.org/10.3390/en14248596 - 20 Dec 2021
Viewed by 272
Abstract
Polymer electrolyte membrane fuel cells were analyzed to investigate changes in the structure of the flow field and operating conditions. The cell performance, which was controlled by adjusting the width of the cathodic channel, improved as the backpressure increases. With the anodic and [...] Read more.
Polymer electrolyte membrane fuel cells were analyzed to investigate changes in the structure of the flow field and operating conditions. The cell performance, which was controlled by adjusting the width of the cathodic channel, improved as the backpressure increases. With the anodic and cathodic flow channels mismatched, the maximum power densities at 3.0 bar for a narrow cathodic channel were 1115 and 1024 mW/cm2, and those for a wide cathodic channel were 959 and 868 mW/cm2, respectively. The diffusion characteristics were investigated using the non-dimensional numbers Re (Reynolds), Sc (Schmidt), and Sh (Sherwood) to confirm the improvement of mass transport. The narrower the channel or the higher the operating pressure, the larger Re was and the smaller Sc and Sh became. In particular, the wider the anodic channel, the larger the value of Sh. Full article
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Article
Robust Enough? Exploring Temperature-Constrained Energy Transition Pathways under Climate Uncertainty
Energies 2021, 14(24), 8595; https://doi.org/10.3390/en14248595 - 20 Dec 2021
Viewed by 245
Abstract
In this paper, we study how uncertainties weighing on the climate system impact the optimal technological pathways the world energy system should take to comply with stringent mitigation objectives. We use the TIAM-World model that relies on the TIMES modelling approach. Its climate [...] Read more.
In this paper, we study how uncertainties weighing on the climate system impact the optimal technological pathways the world energy system should take to comply with stringent mitigation objectives. We use the TIAM-World model that relies on the TIMES modelling approach. Its climate module is inspired by the DICE model. Using robust optimization techniques, we assess the impact of the climate system parameter uncertainty on energy transition pathways under various climate constraints. Unlike other studies we consider all the climate system parameters which is of primary importance since: (i) parameters and outcomes of climate models are all inherently uncertain (parametric uncertainty); and (ii) the simplified models at stake summarize phenomena that are by nature complex and non-linear in a few, sometimes linear, equations so that structural uncertainty is also a major issue. The use of robust optimization allows us to identify economic energy transition pathways under climate constraints for which the outcome scenarios remain relevant for any realization of the climate parameters. In this sense, transition pathways are made robust. We find that the abatement strategies are quite different between the two temperature targets. The most stringent one is reached by investing massively in carbon removal technologies such as bioenergy with carbon capture and storage (BECCS) which have yields much lower than traditional fossil fuelled technologies. Full article
(This article belongs to the Special Issue Decision Making in Energy Systems)
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Article
Heavy-Ion Fusion Reaction Calculations: Establishing the Theoretical Frameworks for 111In Radionuclide over the Coupled Channel Model
Energies 2021, 14(24), 8594; https://doi.org/10.3390/en14248594 - 20 Dec 2021
Viewed by 228
Abstract
In this work, the production of I111n radionuclide has been investigated theoretically via heavy-ion fusion reactions of two stable nuclei: C37l+G74e, M26g+R85b, [...] Read more.
In this work, the production of I111n radionuclide has been investigated theoretically via heavy-ion fusion reactions of two stable nuclei: C37l+G74e, M26g+R85b, S30i+B81r, and C46a+C65u reactions. Fusion cross-sections, barrier distributions, and potential energies on mutual orientations in the reactions planes of all reactions have been researched in detail around the barrier region via a coupled channel (CC) model using different codes. First of all, the most suitable codes and calculation parameter sets were determined through the C37l+G74e reaction, whose experimental data were available. The compatibility of the calculations via NRV knowledge base, CCFULL, CCDEF codes, and Wong’s formula with experimental data was analyzed. Barrier distributions and cross-sections for heavy-ion fusion reactions have been investigated with miscellaneous codes and vibrational-rotational nuclei combinations for interacting nuclei. Afterward, calculations were made with the determined parameter values for new reaction suggestions (M26g+R85b, S30i+B81r, and C46a+C65u reactions) and the results were compared. This study aims to suggest the new reaction combinations for the production of 111In radionuclide, to explore the impacts of different calculation codes and nuclear parameter combinations on the heavy-ion fusion cross-sections and barrier distributions, to demonstrate that the results are reliable, and to emphasize the importance of developing these studies in the preparation of new experiments. Full article
(This article belongs to the Special Issue Nuclear Fusion Energy Development)
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Article
Augmentation of Heat Transfer in a Circular Channel with Inline and Staggered Baffles
Energies 2021, 14(24), 8593; https://doi.org/10.3390/en14248593 - 20 Dec 2021
Viewed by 268
Abstract
This numerical investigation presents the effects of the position of baffles in the shape of a circle’s segment placed inside a circular channel to improve the thermal and flow performance of a solar air heater. Three different baffles’ positions with Reynolds number varying [...] Read more.
This numerical investigation presents the effects of the position of baffles in the shape of a circle’s segment placed inside a circular channel to improve the thermal and flow performance of a solar air heater. Three different baffles’ positions with Reynolds number varying between 10,000 to 50,000 were investigated computationally. The k-omega SST model was used for solving the governing equations. Air was taken as the working fluid. Three pitch ratios (Y = 3, 4, and 5) were considered, while the height of the baffles remained fixed. The result showed an enhancement in Nusselt number, friction factor, j-factor, and thermal performance factor. Staggered exit-length baffles showed maximum enhancement in heat transfer and pressure drop, while inline inlet-length baffles showed the least enhancement. For a pitch ratio of Y = 3.0, the enhancement in all parameters was the highest, while for Y = 5.0, the enhancement in all parameters was the least. The highest thermal performance factor of 1.6 was found for SEL at Y = 3.0. Full article
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Article
Trip Based Modeling of Fuel Consumption in Modern Heavy-Duty Vehicles Using Artificial Intelligence
Energies 2021, 14(24), 8592; https://doi.org/10.3390/en14248592 - 20 Dec 2021
Viewed by 210
Abstract
Heavy-duty trucks contribute approximately 20% of fuel consumption in the United States of America (USA). The fuel economy of heavy-duty vehicles (HDV) is affected by several real-world parameters like road parameters, driver behavior, weather conditions, and vehicle parameters, etc. Although modern vehicles comply [...] Read more.
Heavy-duty trucks contribute approximately 20% of fuel consumption in the United States of America (USA). The fuel economy of heavy-duty vehicles (HDV) is affected by several real-world parameters like road parameters, driver behavior, weather conditions, and vehicle parameters, etc. Although modern vehicles comply with emissions regulations, potential malfunction of the engine, regular wear and tear, or other factors could affect vehicle performance. Predicting fuel consumption per trip based on dynamic on-road data can help the automotive industry to reduce the cost and time for on-road testing. Data modeling can easily help to diagnose the reason behind fuel consumption with a knowledge of input parameters. In this paper, an artificial neural network (ANN) was implemented to model fuel consumption in modern heavy-duty trucks for predicting the total and instantaneous fuel consumption of a trip based on very few key parameters, such as engine load (%), engine speed (rpm), and vehicle speed (km/h). Instantaneous fuel consumption data can help to predict patterns in fuel consumption for optimized fleet operations. In this work, the data used for modeling was collected at a frequency of 1Hz during on-road testing of modern heavy-duty vehicles (HDV) at the West Virginia University Center for Alternative Fuels Engines and Emissions (WVU CAFEE) using the portable emissions monitoring system (PEMS). The performance of the artificial neural network was evaluated using mean absolute error (MAE) and root mean square error (RMSE). The model was further evaluated with data collected from a vehicle on-road trip. The study shows that artificial neural networks performed slightly better than other machine learning techniques such as linear regression (LR), and random forest (RF), with high R-squared (R2) and lower root mean square error. Full article
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Article
The Issue of Operating Security Systems in Terms of the Impact of Electromagnetic Interference Generated Unintentionally
Energies 2021, 14(24), 8591; https://doi.org/10.3390/en14248591 - 20 Dec 2021
Viewed by 259
Abstract
This article discusses issues regarding electromagnetic interference generated unintentionally by transport telematics systems and electronic security systems (ESS) located within a railway area. These systems should operate correctly, since they ensure the safety of both vehicles and passengers. The electronic devices they use [...] Read more.
This article discusses issues regarding electromagnetic interference generated unintentionally by transport telematics systems and electronic security systems (ESS) located within a railway area. These systems should operate correctly, since they ensure the safety of both vehicles and passengers. The electronic devices they use are exposed to electromagnetic interference that may lead to incorrect ESS functioning. In order to determine the impact of electromagnetic interference on ESS, the authors measured unintentional low-frequency electromagnetic field generated by MV—15 and 30 kV—power lines. This enabled determining the areas with maximum values of electromagnetic interference. The next stage of the research was to develop an ESS operating process model that takes into account the impact of unintentionally generated electromagnetic interference on the operating process. Introducing the electromagnetic interference impact coefficient enables a rational selection of solutions aimed at protecting against electromagnetic interference through the application of technical and organizational measures. Full article
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Editorial
Mining Technologies Innovative Development: Economic and Sustainable Outlook
Energies 2021, 14(24), 8590; https://doi.org/10.3390/en14248590 - 20 Dec 2021
Viewed by 203
Abstract
Today science faces the task of ensuring the innovative development of the mineral extractive sector of the economy in resource-rich countries, in the context of unfolding two opposite trends [...] Full article
(This article belongs to the Special Issue Mining Technologies Innovative Development)
Editorial
Advances in Fluid Power Systems
Energies 2021, 14(24), 8589; https://doi.org/10.3390/en14248589 - 20 Dec 2021
Viewed by 248
Abstract
The main purpose of this special edition of “Advances in Fluid Power Systems” was to present new scientific work in the field of fluid power systems for the hydraulic and pneumatic control of machines and devices that are used in various industries [...] [...] Read more.
The main purpose of this special edition of “Advances in Fluid Power Systems” was to present new scientific work in the field of fluid power systems for the hydraulic and pneumatic control of machines and devices that are used in various industries [...] Full article
(This article belongs to the Special Issue Advances in Fluid Power Systems)
Article
Methodology for Assessing the Stability of Drilling Rigs Based on Analytical Tests
Energies 2021, 14(24), 8588; https://doi.org/10.3390/en14248588 - 20 Dec 2021
Viewed by 248
Abstract
Underground mining machines, such as wheel-tyre drilling rigs, are articulated and equipped with booms that project far beyond the undercarriage. Such a structure makes these machines prone to losing stability. Hence, it is necessary to analyse the distribution of masses and geometry as [...] Read more.
Underground mining machines, such as wheel-tyre drilling rigs, are articulated and equipped with booms that project far beyond the undercarriage. Such a structure makes these machines prone to losing stability. Hence, it is necessary to analyse the distribution of masses and geometry as well as their broadly understood stability during the entire design process, taking into account many factors resulting from the manner and conditions of their operation. However, there are no appropriate computational models that would enable analytical tests to be carried out for machines with this kind of construction. This article is concerned with the author’s computational model, which allows the stability of single- and twin-boom drilling rigs to be quickly assessed. The model makes it possible to perform analyses without having to solve differential equations that are present in dynamic models or using specialist software based on CAD and CAE tools. The developed model allows determination of the pressure of wheels and jacks as a function of many important parameters and variables. Additionally, the distances of the centre of gravity from the tipping edge are calculated. The developed computational model was verified by comparing the obtained results with the results of the full dynamic model, the results of model tests carried out in the CAD/CAE program, and the results of empirical tests of wheel and jack pressures on the ground for the selected drilling rig. The model was subjected to verification and validation, which proved that it was fully correct and useful. The model was used to prepare a practical and user-friendly calculation sheet. Apart from the numerical values, the calculation sheet contains a graphical representation of the machine, the location of the centre of gravity, the tipping edges, as well as graphs of the wheel and jack pressures. Next, analytical tests of the stability of the selected drilling rig were carried out. The obtained calculation results are consistent with the results of empirical research. The computational model and the spreadsheet provide handy tools used during the design process by one of the Polish company’s producing drilling rigs. Full article
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Article
Application of the ARMA Model to Describe and Forecast the Flotation Feed Solids Flow Rate
Energies 2021, 14(24), 8587; https://doi.org/10.3390/en14248587 - 20 Dec 2021
Viewed by 247
Abstract
The flow rate of solids is subject to random disturbances of the changing feed and can significantly affect the quantitative and qualitative parameters of the coal flotation products. This quantity can be described as a stochastic process. The paper presents the results of [...] Read more.
The flow rate of solids is subject to random disturbances of the changing feed and can significantly affect the quantitative and qualitative parameters of the coal flotation products. This quantity can be described as a stochastic process. The paper presents the results of the solids flow rate model for coal flotation identification calculations, treated as a disturbance to the process. This is an innovative approach to modelling those quantitative parameters of the flotation feed that are measurably available and whose random changes have a significant impact on the enhancement process under industrial conditions. These include the volumetric flow rate of the feed and, in particular, concentration of solids in the feed. Therefore, it is suggested that random changes of these two parameters of the feed should be mapped using a model of one quantity—the flow rate of solids. This solution is advantageous because this quantity, as a quantitative parameter of the feed, has a significant impact on the course of the coal flotation process. The model is necessary in the process of designing an automatic control system through simulation tests. It allows us to generate a data string simulating random changes to this quantitative parameter of the feed. On this basis, in the simulation model, the correct functioning of the automatic control system is tested, the task of which is to compensate the influence of this disturbance. To determine the empirical model of the feed solids flow rate, measurement data obtained during the registration of the solids concentration and volumetric flow rate of the feed were used in four consecutive periods of operation of an industrial facility of one of the Polish coal processing plants. The time courses of the solids flow rate in the feed were described by ARMA (autoregressive–moving-average model) means, and the two-stage least squares method was used to estimate the model parameters. The results of the identification and verification of the designated model showed the correctness of adopting the third-order ARMA model, with parameters a1 = −1.0682, a2 = −0.2931, a3 = 0.3807, c1 = −0.1588, c2 = −0.2301, c3 = 0.1037, and variance σ2ε = 0.0891, white noise sequence εt, determined on the basis of a series of residuals described by the fifth-order model. It has been shown that the identified model of the flow rate of solids of the feed to flotation as disturbances can be used to develop a predictive model that allows forecasting the modelled quantity with a prediction horizon equal to the sampling period. One-step forecasting based on the determined predictor equation was found to give results consistent with the recorded values of the solid part flow rate of the feed and the extreme values of the prediction error are within the range from −1.08 to 2.90 kg/s. Full article
(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)
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Article
Analysis of Solar Energy Utilization Effect of Air-Based Photovoltaic/Thermal System
Energies 2021, 14(24), 8586; https://doi.org/10.3390/en14248586 - 20 Dec 2021
Viewed by 295
Abstract
Recently, the use of new and renewable energy sources to reduce carbon dioxide emissions and minimize global warming has attracted attention. Among the different renewable energy sources, solar energy is utilized for energy reduction in buildings because of its ease of use and [...] Read more.
Recently, the use of new and renewable energy sources to reduce carbon dioxide emissions and minimize global warming has attracted attention. Among the different renewable energy sources, solar energy is utilized for energy reduction in buildings because of its ease of use and excellent maintenance and repair. In this study, an air-based photovoltaic/thermal (PVT) system that improves solar energy utilization was developed, and its performance was experimentally compared with that of the existing photovoltaic (PV) system. The PVT system could increase the amount of generated power by decreasing the panel temperature raised by the air passing through the lower part of the panel. Moreover, it was possible to use the high-temperature air collected from the panel for heating or hot-water supply in the building. Based on the experimental results obtained for the PV and PVT panels subjected to the same weather conditions, the power generation efficiency of the PVT panel through which air was passed increased by approximately 10.1% compared to that of the PV panel. In addition, a heat collection efficiency of approximately 46.6% was generated by the temperature increase of the air passing through the PVT panel. Full article
(This article belongs to the Special Issue Energy Performance, Management and Recovery in Buildings)
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Review
A Review on Power Electronics Technologies for Power Quality Improvement
Energies 2021, 14(24), 8585; https://doi.org/10.3390/en14248585 - 20 Dec 2021
Viewed by 366
Abstract
Nowadays, new challenges arise relating to the compensation of power quality problems, where the introduction of innovative solutions based on power electronics is of paramount importance. The evolution from conventional electrical power grids to smart grids requires the use of a large number [...] Read more.
Nowadays, new challenges arise relating to the compensation of power quality problems, where the introduction of innovative solutions based on power electronics is of paramount importance. The evolution from conventional electrical power grids to smart grids requires the use of a large number of power electronics converters, indispensable for the integration of key technologies, such as renewable energies, electric mobility and energy storage systems, which adds importance to power quality issues. Addressing these topics, this paper presents an extensive review on power electronics technologies applied to power quality improvement, highlighting, and explaining the main phenomena associated with the occurrence of power quality problems in smart grids, their cause and effects for different activity sectors, and the main power electronics topologies for each technological solution. More specifically, the paper presents a review and classification of the main power quality problems and the respective context with the standards, a review of power quality problems related to the power production from renewables, the contextualization with solid-state transformers, electric mobility and electrical railway systems, a review of power electronics solutions to compensate the main power quality problems, as well as power electronics solutions to guarantee high levels of power quality. Relevant experimental results and exemplificative developed power electronics prototypes are also presented throughout the paper. Full article
(This article belongs to the Special Issue Active Power Filters and Power Quality)
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Article
Assessment of Cumulative Energy Needs for Chosen Technologies of Cattle Feeding in Barns with Conventional (CFS) and Automated Feeding Systems (AFS)
Energies 2021, 14(24), 8584; https://doi.org/10.3390/en14248584 - 20 Dec 2021
Viewed by 260
Abstract
The increasing popularity of automated systems and the increased market share of producers of robotic feeding equipment for cows causes the need for a deeper study of energy demand in such technologies. This article provides an analysis of the inputs of energy accumulated [...] Read more.
The increasing popularity of automated systems and the increased market share of producers of robotic feeding equipment for cows causes the need for a deeper study of energy demand in such technologies. This article provides an analysis of the inputs of energy accumulated in conventional (CFS) and automated feeding systems (AFS) for cattle. The aim of this is to determine the impact of robotic technologies for the preparation and feeding of fodder on the cumulative energy inputs. The aim of this paper is to investigate the effect of machinery and the equipment applied to the cumulative energy intensity in cattle farming facilities. The cumulative energy consumption for four technologies of automated cattle feeding (AFS) was tested and compared to the energy consumption for six technologies with a conventional feeding system (CFS). The research involved nine cow barn facilities for dairy cows and one for beef cattle. An evaluation has been made for cattle farming structures (milk and meat production) with various mixing and feeding systems for feeds of various concentrations, and keeping system (tied system and free-stall). The cow barns differed in feed mixing, feeding machinery, and equipment. Measurements of live labor inputs and the consumption of electric and mechanical energy carriers were carried out, and the mass of various types of machines and devices with software was taken into account, which became the basis for calculating cumulative energy consumption for individual technologies. The obtained average of electric and mechanical energy inputs for robotic technologies of feeding fodder (AFS) was 0.60025 kWh∙day−1∙LU−1(where LU means Large Animal Unit 500 kg), and it was 39.3% lower than for conventional technologies (CFS) where it was 0.989052 kWh∙day−1∙LU−1. However, taking into account all components of cumulative energy consumption, the average for the group of robotic technologies (AFS) was higher by 35.18% than for conventional technologies (CFS). Full article
(This article belongs to the Topic Exergy Analysis and Its Applications)
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Article
Well-Logging Prediction Based on Hybrid Neural Network Model
Energies 2021, 14(24), 8583; https://doi.org/10.3390/en14248583 - 20 Dec 2021
Viewed by 342
Abstract
Well-logging is an important formation characterization and resource evaluation method in oil and gas exploration and development. However, there has been a shortage of well-logging data because Well-logging can only be measured by expensive and time-consuming field tests. In this study, we aimed [...] Read more.
Well-logging is an important formation characterization and resource evaluation method in oil and gas exploration and development. However, there has been a shortage of well-logging data because Well-logging can only be measured by expensive and time-consuming field tests. In this study, we aimed to find effective machine learning techniques for well-logging data prediction, considering the temporal and spatial characteristics of well-logging data. To achieve this goal, the convolutional neural network (CNN) and the long short-term memory (LSTM) neural networks were combined to extract the spatial and temporal features of well-logging data, and the particle swarm optimization (PSO) algorithm was used to determine hyperparameters of the optimal CNN-LSTM architecture to predict logging curves in this study. We applied the proposed CNN-LSTM-PSO model, along with support vector regression, gradient-boosting regression, CNN-PSO, and LSTM-PSO models, to forecast photoelectric effect (PE) logs from other logs of the target well, and from logs of adjacent wells. Among the applied algorithms, the proposed CNN-LSTM-PSO model generated the best prediction of PE logs because it fully considers the spatio-temporal information of other well-logging curves. The prediction accuracy of the PE log using logs of the adjacent wells was not as good as that using the other well-logging data of the target well itself, due to geological uncertainties between the target well and adjacent wells. The results also show that the prediction accuracy of the models can be significantly improved with the PSO algorithm. The proposed CNN-LSTM-PSO model was found to enable reliable and efficient Well-logging prediction for existing and new drilled wells; further, as the reservoir complexity increases, the proxy model should be able to reduce the optimization time dramatically. Full article
(This article belongs to the Special Issue Application of Machine Learning in Rock Characterization)
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Article
A 1.2 kV SiC MOSFET with Integrated Heterojunction Diode and P-shield Region
Energies 2021, 14(24), 8582; https://doi.org/10.3390/en14248582 - 20 Dec 2021
Viewed by 240
Abstract
A 1.2 kV SiC MOSFET with an integrated heterojunction diode and p-shield region (IHP-MOSFET) was proposed and compared to a conventional SiC MOSFET (C-MOSFET) using numerical TCAD simulation. Due to the heterojunction diode (HJD) located at the mesa region, the reverse recovery time [...] Read more.
A 1.2 kV SiC MOSFET with an integrated heterojunction diode and p-shield region (IHP-MOSFET) was proposed and compared to a conventional SiC MOSFET (C-MOSFET) using numerical TCAD simulation. Due to the heterojunction diode (HJD) located at the mesa region, the reverse recovery time and reverse recovery charge of the IHP-MOSFET decreased by 62.5% and 85.7%, respectively. In addition, a high breakdown voltage (BV) and low maximum oxide electric field (EMOX) could be achieved in the IHP-MOSFET by introducing a p-shield region (PSR) that effectively disperses the electric field in the off-state. The proposed device also exhibited 3.9 times lower gate-to-drain capacitance (CGD) than the C-MOSFET due to the split-gate structure and grounded PSR. As a result, the IHP-MOSFET had electrically excellent static and dynamic characteristics, and the Baliga’s figure of merit (BFOM) and high frequency figure of merit (HFFOM) were increased by 37.1% and 72.3%, respectively. Finally, the switching energy loss was decreased by 59.5% compared to the C-MOSFET. Full article
(This article belongs to the Special Issue Advances in Power Electronics Technologies)
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Article
Effect of Seawater and Fly Ash Contaminants on Insulator Surfaces Made of Polymer Based on Finite Element Method
Energies 2021, 14(24), 8581; https://doi.org/10.3390/en14248581 - 20 Dec 2021
Viewed by 213
Abstract
Polymer is an insulating substance that has become increasingly popular in recent years due to its benefits. Light density, superior dielectric and thermal properties, and water-resistant or hydrophobic properties are only a few of the benefits. The presence of impurities or pollutants on [...] Read more.
Polymer is an insulating substance that has become increasingly popular in recent years due to its benefits. Light density, superior dielectric and thermal properties, and water-resistant or hydrophobic properties are only a few of the benefits. The presence of impurities or pollutants on the insulator’s surface lowers its dielectric capacity, which can lead to current leakage. The influence of seawater and fly ash pollutants on the distribution of the electric field and the current density of the insulator was simulated in this study. The finite element method was used to execute the simulation (FEM). Polymer insulators are subjected to testing in order to gather current leakage statistics. The tested insulator is exposed to seawater pollution, which varies depending on the equivalent salt density deposit value (ESDD). The pollutant insulator for fly ash varies depending on the value of non-soluble deposit density (NSDD). The existence of a layer of pollutants increased the value of the electric field and the value of the surface current density, according to the findings. Both in simulation and testing, the ESDD value of seawater pollutants and the NSDD value of fly ash contaminants influenced the value of the leakage current that flowed. The greater the ESDD and NSDD values are, the bigger the leakage current will be. Full article
(This article belongs to the Special Issue Advanced Research of High Voltage Insulation)
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Article
A New Prediction Method for the Complete Characteristic Curves of Centrifugal Pumps
Energies 2021, 14(24), 8580; https://doi.org/10.3390/en14248580 - 20 Dec 2021
Viewed by 246
Abstract
Complete pump characteristics (CPCs) are the key for establishing pump boundary conditions and simulating hydraulic transients. However, they are not normally available from manufacturers, making pump station design difficult to carry out. To solve this issue, a novel method considering the inherent operating [...] Read more.
Complete pump characteristics (CPCs) are the key for establishing pump boundary conditions and simulating hydraulic transients. However, they are not normally available from manufacturers, making pump station design difficult to carry out. To solve this issue, a novel method considering the inherent operating characteristics of the centrifugal pump is therefore proposed to predict the CPCs. First, depending on the Euler equations and the velocity triangles at the pump impeller, a mathematical model describing the complete characteristics of a centrifugal pump is deduced. Then, based on multiple measured CPCs, the nonlinear functional relationship between the characteristic parameters of the characteristic operating points (COPs) and the specific speed is established. Finally, by combining the mathematical model with the nonlinear relationship, the CPCs for a given specific speed are successfully predicted. A case study shows that the predicted CPCs are basically consistent with the measured data, showing a high prediction accuracy. For a pump-failure water hammer, the simulated results using the predicted CPCs are close to that using the measured data with a small deviation. This method is easy to program and the prediction accuracy meets the requirements for hydraulic transient simulations, providing important data support for engineering design. Full article
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Article
Suppression Method of Partial Discharge Interferences Based on Singular Value Decomposition and Improved Empirical Mode Decomposition
Energies 2021, 14(24), 8579; https://doi.org/10.3390/en14248579 - 20 Dec 2021
Viewed by 251
Abstract
Partial discharge detection is an important means of insulation diagnosis of electrical equipment. To effectively suppress the periodic narrowband and white noise interferences in the process of partial discharge detection, a partial discharge interference suppression method based on singular value decomposition (SVD) and [...] Read more.
Partial discharge detection is an important means of insulation diagnosis of electrical equipment. To effectively suppress the periodic narrowband and white noise interferences in the process of partial discharge detection, a partial discharge interference suppression method based on singular value decomposition (SVD) and improved empirical mode decomposition (IEMD) is proposed in this paper. First, the partial discharge signal with periodic narrowband interference and white noise interference x(t) is decomposed by SVD. According to the distribution characteristics of single values of periodic narrowband interference signals, the singular value corresponding to periodic narrowband interference is set to zero, and the signal is reconstructed to eliminate the periodic narrowband interference in x(t). IEMD is then performed on x(t). Intrinsic mode function (IMF) is obtained by EMD, and based on the improved 3σ criterion, the obtained IMF components are statistically processed and reconstructed to suppress the influence of white noise interference. The methods proposed in this paper, SVD and SVD + EMD, are applied to process the partial discharge simulation signal and partial discharge measurement signal, respectively. We calculated the signal-to-noise ratio, normalized correlation coefficient, and mean square error of the three methods, respectively, and the results show that the proposed method suppresses the periodic narrowband and white noise interference signals in partial discharge more effectively than the other two methods. Full article
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Article
Smart Modulation for Control Systems with High Regulation Capabilities for Cooling Systems Optimisation and Carbon Footprint Reduction in Industry
Energies 2021, 14(24), 8578; https://doi.org/10.3390/en14248578 - 20 Dec 2021
Viewed by 271
Abstract
Nowadays, every large enterprise is concerned about reducing CO2 emissions. Along with legislation, management, packaging, and transportation decisions, optimising the operation of automated systems in the industry is important. Overheating processes or large cooling systems of one machine during product assembly may [...] Read more.
Nowadays, every large enterprise is concerned about reducing CO2 emissions. Along with legislation, management, packaging, and transportation decisions, optimising the operation of automated systems in the industry is important. Overheating processes or large cooling systems of one machine during product assembly may seem minor but at the industry level it is quite significant. Either an optimisation of cooling systems or an intelligent machine control which will prevent heat strokes and allow the transition to passive cooling of the whole system is an important issue for improving machine tools efficiency and contributing therefore to CO2 reduction in the industry sector. This research is a transitional phase from the creation of a control system to solve the problems of resonance in the control of systems with parallel piezo kinematics, which were designed to automate the iterative process of non-circular drilling with a precise shape and the subsequent research on the implementation of smart control to optimise the cooling of industrial machines. The total dynamics of the example system in this research is unknown and consists of the dynamics of electrical converters, piezo kinematics, and mechanics. The control signal of this system is generated by the model of the system state with assumptions and simplifications in combination with machine learning techniques considering the previous errors of the transient characteristics with the possibility of re-drilling without damaging the workpiece and with possibility of further trainings to eliminate the iterative process in general. Algorithms for further training at different resonances with a drilling depth change for cylinders of internal combustion engines are offered. These algorithms are proposed for accurate transmission of the input signal amplitude even in resonant situations, power optimisation, increase the system efficiency, as well as reducing the carbon footprint when used in industry in specific applications. Full article
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Editorial
Editorial for Special Issue: “Clean Energy Innovations: Challenges and Strategies for Low and Middle Income Countries”
by and
Energies 2021, 14(24), 8577; https://doi.org/10.3390/en14248577 - 20 Dec 2021
Viewed by 240
Abstract
All the papers in this Special Issue situate their research in the context of a failing clean cooking strategy and the potential contribution of electricity to this [...] Full article
Article
Photovoltaic Solar Energy from Urban Sprawl: Potential for Poland
Energies 2021, 14(24), 8576; https://doi.org/10.3390/en14248576 - 20 Dec 2021
Viewed by 423
Abstract
Urban sprawl is a process that shapes contemporary urban spaces. Generally, this process is associated with negative effects due to the generation of high costs. However, not all the effects of urban sprawl should be considered in the context of the increasing costs [...] Read more.
Urban sprawl is a process that shapes contemporary urban spaces. Generally, this process is associated with negative effects due to the generation of high costs. However, not all the effects of urban sprawl should be considered in the context of the increasing costs of the use of space; some of them should be regarded as cost cutting factors, for example, the possibility of the use of roofed areas in generating energy from sunlight. Solar energy is believed to be one of the sources of clean energy that reduce pollution and greenhouse gas emissions into the atmosphere. However, solar energy generation necessitates the development of large areas for the purpose of installing photovoltaic modules and substantial funds for creating large solar farms. For this reason, a significant role in state energy policies is played by small dispersed installations mounted on the roofs of buildings. There is a gap in existing research on the assessment of urban sprawl in terms of the potential use of rooftops for solar installations in suburban areas. This research gap has not yet been filled, either conceptually and methodologically. Hence, the contribution of the research to the development of the current state of knowledge involves the identification of economic and environmental benefits of usually negatively perceived urban sprawl. The proposal of a method for the identification of suburban housing potential for solar energy generation constitutes another addition to the state of knowledge. The main objective of this article is to analyse the energy generating potential of buildings located in suburban and urban areas characterised by the confirmed occurrence of urban sprawl phenomena. CityGML data were used to conduct an analysis of the exposure of roofs to sunlight using algorithms based on vector data. The authors estimated the dynamics of changes in time and referred the existing photovoltaic installations to the total potential of a selected area. The use of the energy potential of the analysed roofs of buildings was used to evaluate the external costs and benefits of spatial planning. The discussion presented the current conditions of the energy sector and energy policies in Poland and the EU. In addition, recommendations were proposed for local spatial policies concerning the mitigation of the effects of suburbanization in the context of developing the system of PV micro-installations. Full article
(This article belongs to the Special Issue The Role of Spatial Policy Tools in Renewable Energy Investment)
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