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Search Results (9,725)

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Keywords = energy data analysis

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14 pages, 9322 KiB  
Article
Metabolic Reprogramming Induced by Aging Modifies the Tumor Microenvironment
by Xingyu Chen, Zihan Wang, Bo Zhu, Min Deng, Jiayue Qiu, Yunwen Feng, Ning Ding and Chen Huang
Cells 2024, 13(20), 1721; https://doi.org/10.3390/cells13201721 (registering DOI) - 17 Oct 2024
Abstract
Aging is an important risk factor for tumorigenesis. Metabolic reprogramming is a hallmark of both aging and tumor initiation. However, the manner in which the crosstalk between aging and metabolic reprogramming affects the tumor microenvironment (TME) to promote tumorigenesis was poorly explored. We [...] Read more.
Aging is an important risk factor for tumorigenesis. Metabolic reprogramming is a hallmark of both aging and tumor initiation. However, the manner in which the crosstalk between aging and metabolic reprogramming affects the tumor microenvironment (TME) to promote tumorigenesis was poorly explored. We utilized a computational approach proposed by our previous work, MMP3C (Modeling Metabolic Plasticity by Pathway Pairwise Comparison), to characterize aging-related metabolic plasticity events using pan-cancer bulk RNA-seq data. Our analysis revealed a high degree of metabolically organized heterogeneity across 17 aging-related cancer types. In particular, a higher degree of several energy generation pathways, i.e., glycolysis and impaired oxidative phosphorylation, was observed in older patients. Similar phenomena were also found via single-cell RNA-seq analysis. Furthermore, those energy generation pathways were found to be weakened in activated T cells and macrophages, whereas they increased in exhausted T cells, immunosuppressive macrophages, and Tregs in older patients. It was suggested that aging-induced metabolic switches alter glucose utilization, thereby influencing immune function and resulting in the remodeling of the TME. This work offers new insights into the associations between tumor metabolism and the TME mediated by aging, linking with novel strategies for cancer therapy. Full article
(This article belongs to the Section Cellular Metabolism)
15 pages, 3214 KiB  
Article
Influence of Particle Size on Flotation Separation of Ilmenite and Forsterite
by Senpeng Zhang, Yaohui Yang, Donghui Wang, Weiping Yan and Weishi Li
Minerals 2024, 14(10), 1041; https://doi.org/10.3390/min14101041 - 17 Oct 2024
Abstract
In addition to bubble–particle interaction, particle–particle interaction also has a significant influence on mineral flotation. Fine particles that coat the mineral surface prevent direct contact with collectors and/or air bubbles, thereby lowering flotation recovery. Calculating the particle interaction energy can help in evaluating [...] Read more.
In addition to bubble–particle interaction, particle–particle interaction also has a significant influence on mineral flotation. Fine particles that coat the mineral surface prevent direct contact with collectors and/or air bubbles, thereby lowering flotation recovery. Calculating the particle interaction energy can help in evaluating the interaction behavior of particles. In this study, the floatability of coarse ilmenite (−151+74 μm) and different particle sizes (−45+25, −25+19, −19 μm) of forsterite with NaOL as a collector was investigated. The results showed that forsterite sizes of −45+25 and −25+19 μm had no effect on the ilmenite floatability, whereas −19 μm forsterite significantly reduced ilmenite floatability. A particle size analysis of artificially mixed minerals and a scanning electron microscopy (SEM) analysis of the flotation products showed that heterogeneous aggregation occurred between ilmenite and −19 μm forsterite particles. The extended DLVO (Derjaguin–Landau–Verwey–Overbeek) theory was applied to calculate the interaction energy between mineral particles using data from zeta potential and contact angle measurements. The results showed that the interaction barriers between ilmenite (−151+74 μm) and forsterite (−45+25, −25+19, and −19 μm) were 11.94 × 103 kT, 8.23 × 103 kT and 4.09 × 103 kT, respectively. Additionally, the interaction barrier between forsterite particles smaller than 19 μm was 0.51 × 103 kT. The strength of the barrier decreased as the size of the forsterite decreased. Therefore, fine forsterite particles and aggregated forsterite can easily overcome the energy barrier, coating the ilmenite particle surface. This explains the effect of different forsterite sizes on the floatability of ilmenite and the underlying mechanism of particle interaction. Full article
21 pages, 3570 KiB  
Article
Structural Market Power in the Presence of Renewable Energy Sources
by Bahareh Sirjani, Asghar Akbari Foroud, Najmeh Bazmohammadi and Juan C. Vasquez
Electronics 2024, 13(20), 4098; https://doi.org/10.3390/electronics13204098 - 17 Oct 2024
Abstract
Assessing market power in the presence of different production technologies such as renewable energies, including wind and solar power, is crucial for electric market analysis and operation. This paper investigates structural market power by incorporating wind farms and solar generation over a short-term [...] Read more.
Assessing market power in the presence of different production technologies such as renewable energies, including wind and solar power, is crucial for electric market analysis and operation. This paper investigates structural market power by incorporating wind farms and solar generation over a short-term period. The study examines the issue of market concentration boundaries to assess structural market power by calculating the minimum and maximum market concentration index values in the day-ahead market. It models the technical specifications of power plants, such as the maximum and minimum production limits, ramp-up and ramp-down rates, and minimum required up and down times. By extracting the spatiotemporal correlation of wind power generation from real data, the uncertainty of renewable power generation is represented through a set of scenarios. The analysis explores the correlation effects of wind farms, solar generation, and wind penetration levels under different ownership structures. Simulation results using a modified PJM five-bus system illustrate the effectiveness of the developed method. Our results indicate that integrating renewable energy can reduce the Herfindahl–Hirschman Index (HHI) by up to 30% as wind penetration levels rise from 0% to 40%, fostering a more competitive market structure. However, the correlation between wind farms also increases market volatility, with the standard deviation of the HHI rising by about 25% during peak load periods. These findings demonstrate the practical applicability of the developed methodology for assessing market dynamics in the presence of renewable energy sources. Full article
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<p>Pseudocode for the proposed wind scenario generation process.</p>
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<p>Set of 100 scenarios of wind generation for (<b>a</b>) Farm 1, (<b>b</b>) Farm 2.</p>
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<p>Mean and STD of wind generation scenarios with and without FFSR method: (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Correlation coefficient (<b>a</b>) between historical data of two farms, (<b>b</b>) between the generated scenarios of two farms.</p>
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<p>Correlation coefficient (<b>a</b>) between historical data of two farms, (<b>b</b>) between the generated scenarios of two farms.</p>
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<p>Pseudocode for the proposed statistical analysis method.</p>
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<p>Single-line diagram of the 5-bus case study.</p>
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<p>Daily load profiles for the 5-bus case study.</p>
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<p>Daily solar power generation patterns.</p>
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<p>Minimum value of HHI with and without accounting for the correlation of wind generation in base load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Minimum value of HHI with and without accounting for the correlation of wind generation in average load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Minimum value of HHI with and without accounting for the correlation of wind generation in average load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Minimum value of HHI with and without accounting for the correlation of wind generation in peak load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Maximum value of HHI with and without accounting for the correlation of wind generation in base load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Maximum value of HHI with and without accounting for the correlation of wind generation in average load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Maximum value of HHI with and without accounting for the correlation of wind generation in average load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Maximum value of HHI with and without accounting for the correlation of wind generation in peak load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Minimum value of HHI with increasing level of wind penetration in average load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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<p>Maximum value of HHI with increasing level of wind penetration in average load level for (<b>a</b>) mean, (<b>b</b>) STD.</p>
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23 pages, 5670 KiB  
Article
Comparative Analysis and Integrated Methodology for the Electrical Design and Performance Evaluation of Thermoelectric Generators (TEGs) in Energy Harvesting Applications
by Oswaldo Hideo Ando Junior, Eder Andrade da Silva, Emerson Rodrigues de Lira, Sergio Vladimir Barreiro Degiorgi and João Paulo Pereira do Carmo
Energies 2024, 17(20), 5176; https://doi.org/10.3390/en17205176 - 17 Oct 2024
Abstract
This study presents a comparative analysis of the accuracy of different methodologies for the design and performance evaluation of thermoelectric generators (TEGs), using analytical, computational numerical, and experimental approaches. TEGs are promising devices for capturing waste energy in industrial processes, converting waste heat [...] Read more.
This study presents a comparative analysis of the accuracy of different methodologies for the design and performance evaluation of thermoelectric generators (TEGs), using analytical, computational numerical, and experimental approaches. TEGs are promising devices for capturing waste energy in industrial processes, converting waste heat into electrical energy and contributing to energy sustainability. However, the efficiency of TEGs is a significant challenge due to their low conversion rates. To address this challenge, three different methodologies were developed and systematically compared. Analytical Model: Developed for the electrical design of thermoelectric micro generators, using theoretical performance data and industrial temperature gradients. This method offers a robust theoretical view but may not capture all practical variables. Computational model in Simulink/MATLAB: Created and validated to consider the variation of the Seebeck coefficient and the internal resistance of thermoelectric modules with temperature. This model provides an accurate simulation of operating conditions but depends on the accuracy of the input parameters. Experimental Multi-string Electrical Arrangement Prototype: This involved the design and construction of a prototype followed by experimental tests to validate its performance. This method provides valuable empirical data but can be limited by the complexity and cost of the experiments. The results show that each methodology has specific advantages and limitations, offering valuable insights for the development of more efficient TEG systems. The comparison of analytical, numerical, and experimental methods revealed differences in accuracy and efficiency, highlighting the importance of an integrated approach to TEG design. This study lays a solid foundation for future research and practical applications in the field of industrial residual energy harvesting. Full article
(This article belongs to the Special Issue Distributed Energy Resources: Advances, Challenges and Future Trends)
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<p>Block diagram demonstration of the TEG system.</p>
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<p>Graph and diagram on MPPT operation [<a href="#B20-energies-17-05176" class="html-bibr">20</a>,<a href="#B21-energies-17-05176" class="html-bibr">21</a>].</p>
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<p>Energy utilization in DC–DC converters (4).</p>
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<p>Performance curves (voltage, current, and power) as a function of ΔT [<a href="#B37-energies-17-05176" class="html-bibr">37</a>].</p>
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<p>Performance curve of generated voltage as a function of hot and cold temperatures [<a href="#B38-energies-17-05176" class="html-bibr">38</a>].</p>
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<p>Design of the proposed (<b>a</b>) and demonstrated parts and pieces of the generator (<b>b</b>).</p>
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<p>Internal view of the thermoelectric modules in Simulink<sup>®</sup>.</p>
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<p>Computational simulation results (no load) test (INBC1-127.08HTS).</p>
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<p>Demonstration of circuit modeling with variable load.</p>
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<p>Presents of computational simulation results (with load): (<b>a</b>) the output voltage versus output current curve; (<b>b</b>) the output power versus output current curve; and (<b>c</b>) the output power versus output voltage curve as a function of the temperature gradient.</p>
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<p>Presentation of experimental results (no load)—a graph of the output voltage in the open circuit test (INBC1-127.08HTS).</p>
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<p>Presentation of experimental results (with load): (<b>a</b>) the output voltage versus output current curve; (<b>b</b>) the output power versus output current curve; and (<b>c</b>) the output power versus output voltage curve as a function of the temperature gradient.</p>
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<p>Demonstration of buck converter circuit with a resistive load.</p>
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<p>Computational simulation results (open circuit and with load).</p>
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18 pages, 8018 KiB  
Article
Photovoltaic Power Intermittency Mitigating with Battery Storage Using Improved WEEC Generic Models
by André Fernando Schiochet, Paulo Roberto Duailibe Monteiro, Thiago Trezza Borges, João Alberto Passos Filho and Janaína Gonçalves de Oliveira
Energies 2024, 17(20), 5166; https://doi.org/10.3390/en17205166 - 17 Oct 2024
Abstract
The growing integration of renewable energy sources, such as photovoltaic and wind systems, into energy grids has underscored the need for reliable control mechanisms to mitigate the inherent intermittency of these sources. According to the Brazilian grid operator (ONS), there have been cascading [...] Read more.
The growing integration of renewable energy sources, such as photovoltaic and wind systems, into energy grids has underscored the need for reliable control mechanisms to mitigate the inherent intermittency of these sources. According to the Brazilian grid operator (ONS), there have been cascading disconnections in renewable energy distributed systems (REDs) in recent years, highlighting the need for robust control models. This article addresses this issue by presenting the validation of an active power ramp rate control (PRRC) function for a PV plant coupled with a Battery Energy Storage System (BESS) using WECC generic models. The proposed model underwent rigorous validation over an extended analysis period, demonstrating good accuracy using the Root Mean Squared Error (RMSE) and an R-squared (R2) metrics for the active power injected at the Point of Connection (POI), PV active power, and BESS State of Charge (SOC), providing valuable insights for medium and long-term analyses. The ramp rate control module was implemented within the plant power controller (PPC), leveraging second-generation Renewable Energy Systems (RES) models developed by the Western Electricity Coordination Council (WECC) as a foundational framework. We conducted simulations using the Anatem software, comparing the results with real-world data collected at 100 ms to 1000 ms intervals from a PV plant equipped with a BESS in Brazil. The proposed model underwent rigorous validation over an extended analysis period, with the presented results based on two days of measurements. The positive sequence model used to represent this control demonstrated good accuracy, as confirmed by metrics such as the Root Mean Squared Error (RMSE) and R-squared (R2). Furthermore, the article underscores the critical role of accurately accounting for the power sampling rate when calculating the ramp rate. Full article
(This article belongs to the Special Issue Grid Integration of Renewable Energy Conversion Systems)
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<p>Ramp rate Calculation Techniques.</p>
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<p>PV Model with network solution. Source: Author, adapted from [<a href="#B11-energies-17-05166" class="html-bibr">11</a>].</p>
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<p>BESS Model considering the new Ramp Rate Control function in the Plant Controller. Source: Author, adapted from [<a href="#B11-energies-17-05166" class="html-bibr">11</a>].</p>
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<p>Ramp rate control (RR_Control) implemented in the REPC_A controller.</p>
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<p>Ramp rate control using the Rate LM block.</p>
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<p>Block Diagram of the Charging/Discharging Mechanism of the BESS Model (REEC_C). Source: Author, adapted from [<a href="#B9-energies-17-05166" class="html-bibr">9</a>].</p>
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<p>Flowchart illustrating the Improved WECC 2nd Generation Model implementation and validation for PV and BESS [<a href="#B11-energies-17-05166" class="html-bibr">11</a>].</p>
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<p>5-bus test system with the association of Anatem codes (DMDG and DFNT) and Bus Type (<span class="html-italic">P-V</span>, <span class="html-italic">V-θ and P-Q)</span>.</p>
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<p>Active Power Measured in the POI, in the PV and BESS SOC. (<b>a</b>) Day 1—RR = 150 kW/min; (<b>b</b>) Day 2—RR = 100 kW/min.</p>
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<p>Histogram of accumulated Active Power Ramp Rate in the PV. Analysis of the sampling period ∆<span class="html-italic">t</span> and its impact on the calculation of the ramp rate control. (<b>a</b>) Day 1—RR = 150 kW/min; (<b>b</b>) Day 2—RR = 100 kW/min.</p>
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<p>Histogram of accumulated Active Power Ramp Rate in the POI. Analysis of the sampling period ∆<span class="html-italic">t</span> and its impact on the calculation of the ramp rate control. (<b>a</b>) Day 1—RR = 150 kW/min; (<b>b</b>) Day 2—RR = 100 kW/min.</p>
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<p>Represents a PV plant associated with BESS for ramp rate control.</p>
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<p>Comparison of the Anatem ramp rate control simulation results with real PV data for a 100 kW/min rate and ∆<span class="html-italic">t</span> = 60 s.</p>
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<p>Comparison of the Anatem ramp rate control simulation results with real POI data for a rate of 100 kW/min and ∆<span class="html-italic">t</span> = 60 s.</p>
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<p>Comparison of the Anatem ramp rate control simulation results with real BESS SOC data for a rate of 100 kW/min and ∆<span class="html-italic">t</span> = 60 s.</p>
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<p>Validation of Anatem ramp rate control simulation results with real data for a 100 kW/min rate.</p>
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22 pages, 4837 KiB  
Article
A Machine Learning Approach to Forecasting Hydropower Generation
by Sarah Di Grande, Mariaelena Berlotti, Salvatore Cavalieri and Roberto Gueli
Energies 2024, 17(20), 5163; https://doi.org/10.3390/en17205163 - 17 Oct 2024
Viewed by 99
Abstract
In light of challenges like climate change, pollution, and depletion of fossil fuel reserves, governments and businesses prioritize renewable energy sources such as solar, wind, and hydroelectric power. Renewable energy forecasting models play a crucial role for energy market operators and prosumers, aiding [...] Read more.
In light of challenges like climate change, pollution, and depletion of fossil fuel reserves, governments and businesses prioritize renewable energy sources such as solar, wind, and hydroelectric power. Renewable energy forecasting models play a crucial role for energy market operators and prosumers, aiding in planning, decision-making, optimization of energy sales, and evaluation of investments. This study aimed to develop machine learning models for hydropower forecasting in plants integrated into Water Distribution Systems, where energy is generated from water flow used for municipal water supply. The study involved developing and comparing monthly and two-week forecasting models, utilizing both one-step-ahead and two-step-ahead forecasting methodologies, along with different missing data imputation techniques. The tested algorithms—Seasonal Autoregressive Integrated Moving Average, Random Forest, Temporal Convolutional Network, and Neural Basis Expansion Analysis for Time Series—produced varying levels of performance. The Random Forest model proved to be the most effective for monthly forecasting, while the Temporal Convolutional Network delivered the best results for two-week forecasting. Across all scenarios, the seasonal–trend decomposition using the LOESS technique emerged as the most successful for missing data imputation. The accurate predictions obtained demonstrate the effectiveness of using these models for energy planning and decision-making. Full article
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Figure 1
<p>Comparison between time series with outliers (in gray) and time series after outliers detection through single boxplot (in blue).</p>
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<p>Comparison between time series with outliers (in gray) and time series after outliers detection through multiple boxplots (in green).</p>
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<p>Comparison between the two time series aggregated monthly after reconstruction with the two different methods. The gray dashed line in the plot defines the starting point of the non-reconstructed data, which is used as the test set.</p>
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<p>Comparison between the two time series aggregated every two weeks after reconstruction with the two different methods. The gray dashed line in the plot defines the starting point of the non-reconstructed data, which is used as the test set.</p>
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<p>Comparison between actual and forecasted values for the four monthly models using datasets with STL reconstruction.</p>
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<p>SMAPE results of the four best-performing models for monthly hydropower forecasts.</p>
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<p>Comparison between actual and forecasted values from the four two-week models using datasets with STL reconstruction.</p>
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<p>SMAPE results of the four best-performing models for two-week hydropower forecasts.</p>
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17 pages, 4164 KiB  
Article
Evolutionary Game Analysis Between Large Power Consumers and Power Sellers in the Context of Big-Data-Driven Value-Added Services
by Hua Pan, Xin Song, Jianchao Hou and Siyi Tan
Sustainability 2024, 16(20), 8974; https://doi.org/10.3390/su16208974 - 17 Oct 2024
Viewed by 318
Abstract
As power system reforms deepen, direct trading with large power consumers has emerged as a crucial aspect of opening up the power sales market. In light of this trend, power sales enterprises should accelerate their digital transformation in response to the growing demand [...] Read more.
As power system reforms deepen, direct trading with large power consumers has emerged as a crucial aspect of opening up the power sales market. In light of this trend, power sales enterprises should accelerate their digital transformation in response to the growing demand for personalized services from large consumers and continuous advancements in energy digitalization and smart technologies. In particular, big data technology is critical for power enterprises to satisfy users and increase profitability as it can help enterprises gain deeper insights into user needs and behavioral characteristics. The application of big data to provide customized value-added services for large power consumers has become a key development focus. In this paper, we develop a two-party evolutionary game model involving power sellers using big data technology to profile large consumers and offer them customized value-added power packages. We conduct a detailed analysis of the local stability of equilibrium points and employ MATLAB.R2021a to examine the impact of changes in the benefits of value-added services for large consumers and the cost coefficients associated with big data on the system’s evolutionary outcomes. The study results indicate that big data technology can enhance the competitiveness of power sellers in the market. Value-added services based on user-profiling using big data have become a crucial factor in influencing the decision-making behavior of large consumers. Additionally, the investment cost in big data infrastructure by power sellers impacts system evolution, with the cost coefficient being inversely proportional to their willingness to offer customized services. Full article
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<p>Game flow chart.</p>
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<p>Replicator dynamics phase diagram of power sellers.</p>
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<p>Replicator dynamics phase diagram of large consumers.</p>
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<p>Simulation results of evolutionary game stable point (0, 0) <math display="inline"><semantics> <mrow> <mfenced separators="|"> <mrow> <msub> <mrow> <mi>Q</mi> </mrow> <mrow> <mn>1</mn> </mrow> </msub> <mo>+</mo> <mi>P</mi> <mo>−</mo> <msub> <mrow> <mi>Q</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <mo>&gt;</mo> <msub> <mrow> <mi>C</mi> </mrow> <mrow> <mi>n</mi> </mrow> </msub> </mrow> </mfenced> </mrow> </semantics></math>.</p>
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<p>Simulation results of evolutionary game stable point (0, 0) <math display="inline"><semantics> <mrow> <mo stretchy="false">(</mo> <mn>0</mn> <mo>&lt;</mo> <mstyle scriptlevel="0" displaystyle="true"> <mfrac> <mrow> <msub> <mrow> <mi>Q</mi> </mrow> <mrow> <mn>3</mn> </mrow> </msub> <mo>−</mo> <msub> <mrow> <mi>Q</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> </mrow> <mrow> <mi>M</mi> <mo>+</mo> <msub> <mrow> <mi>Q</mi> </mrow> <mrow> <mn>1</mn> </mrow> </msub> <mo>−</mo> <msub> <mrow> <mi>Q</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <mo>−</mo> <mi>W</mi> </mrow> </mfrac> </mstyle> <mo>&lt;</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> </semantics></math>.</p>
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<p>Evolution of initial values <span class="html-italic">α</span> and <span class="html-italic">β</span> at W = 150, 350, and 650.</p>
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<p>Evolution of initial values α and α at <math display="inline"><semantics> <mrow> <mi>W</mi> <mo>/</mo> <msub> <mrow> <mi>C</mi> </mrow> <mrow> <mi>n</mi> </mrow> </msub> </mrow> </semantics></math> = 0.5, 1, 2, 4.</p>
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<p>Evolution of initial values <span class="html-italic">α</span> and <span class="html-italic">β</span> at k = 200.</p>
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18 pages, 1949 KiB  
Review
Geochemical and Physical Methods for Estimating the Saturation of Natural Gas Hydrates in Sediments: A Review
by Yuan Xue, Hailong Lu, Hailin Yang, Wenjiu Cai and Linsen Zhan
J. Mar. Sci. Eng. 2024, 12(10), 1851; https://doi.org/10.3390/jmse12101851 - 16 Oct 2024
Viewed by 344
Abstract
The saturation of natural gas hydrates is a key parameter for characterizing hydrate reservoirs, estimating hydrate reserves, and developing hydrate as an energy resource. Several methods have been proposed to estimate hydrate saturation, although most of these studies rely on logging and seismic [...] Read more.
The saturation of natural gas hydrates is a key parameter for characterizing hydrate reservoirs, estimating hydrate reserves, and developing hydrate as an energy resource. Several methods have been proposed to estimate hydrate saturation, although most of these studies rely on logging and seismic data. However, the methods for estimating hydrate saturation from recovered core sediments have not been thoroughly reviewed, which hinders a deeper understanding, proper application, and the use of these experimental data to integrate geophysical and numerical model results with the actual geological conditions. In this paper, the methods widely used for estimating natural gas hydrate saturation from core sediments, including those based on pore water chemistry (Cl concentration, δD, and δ18O values), gas volumetric analysis, and temperature anomaly, have been summarized in terms of the principle, estimation strategy, and issues to be considered of each method. The applicability, advantages and disadvantages, and scope of application of each method are also compared and discussed. All methods for estimating gas hydrate saturation have certain limitations. A comprehensive application of results from multiple methods could lead to a better understanding of the amount of gas hydrate in sediments, although the chlorinity of pore water is the most commonly used method of estimation. Full article
(This article belongs to the Special Issue Advances in Marine Gas Hydrates)
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<p>Morphologies of natural gas hydrates in sediments: (<b>a</b>) pore-filling hydrates, existing in sediment pores; (<b>b</b>) fracture-filling hydrates, randomly distributed along faults or fractures. The dark blue color represents gas hydrates, while the brown color denotes sediments.</p>
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<p>Three hydrate crystal structures.</p>
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<p>Profiles of ion concentrations in pore water under different conditions. (<b>a</b>) Increase in pore water Cl<sup>−</sup> concentration at a specific depth due to ion exclusion during rapid hydrate formation. (<b>b</b>) Reduction in Cl<sup>−</sup> concentration caused by pore water advection and diffusion. (<b>c</b>) Recovery of Cl<sup>−</sup> concentration to its original level after an extended period of complete advective and diffusive processes in the pore water. (<b>d</b>) Decrease in pore water Cl<sup>−</sup> concentration at a specific depth due to the freshening effect during hydrate dissociation. (<b>e</b>) A general profile of SO<sub>4</sub><sup>2−</sup> concentration in pore water of sediments with scarce organic matter and an extremely low hydrocarbon flux. (<b>f</b>) A profile of SO<sub>4</sub><sup>2−</sup> concentration in pore water of sediments with a certain content of organic matter and hydrocarbon flux.</p>
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<p>Schematic of temperature and corresponding infrared image (<b>a</b>), Cl<sup>−</sup> concentration (<b>b</b>), δD (<b>c</b>), δ<sup>18</sup>O (<b>d</b>), and the hydrate saturation (<b>e</b>) estimated from these parameters.</p>
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<p>A schematic sketch of the pressure curve (blue) and temperature curve (red) of the hydrate dissociation experiment. t<sub>0</sub> marks the beginning of the experiment; t<sub>a</sub>, t<sub>b</sub>, t<sub>c</sub>, and t<sub>d</sub> denote key time points in the experimental process; and t<sub>e</sub> indicates the end of the experiment.</p>
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16 pages, 417 KiB  
Article
Bioelectrical Impedance Analysis Demonstrates Reliable Agreement with Dual-Energy X-ray Absorptiometry in Identifying Reduced Skeletal Muscle Mass in Patients with Metabolic Dysfunction-Associated Steatotic Liver Disease and Hypertension
by Anna F. Sheptulina, Ekaterina O. Lyusina, Elvira M. Mamutova, Adel A. Yafarova, Anton R. Kiselev and Oxana M. Drapkina
Diagnostics 2024, 14(20), 2301; https://doi.org/10.3390/diagnostics14202301 - 16 Oct 2024
Viewed by 246
Abstract
Background/Objectives: Body composition (BC) affects the risk of developing metabolic dysfunction-associated steatotic liver disease (MASLD) and hypertension (HTN). Currently, dual-energy X-ray absorptiometry (DEXA) is considered the gold standard for assessing BC, even though it has some limitations, including immobility, ionizing radiation, and patient [...] Read more.
Background/Objectives: Body composition (BC) affects the risk of developing metabolic dysfunction-associated steatotic liver disease (MASLD) and hypertension (HTN). Currently, dual-energy X-ray absorptiometry (DEXA) is considered the gold standard for assessing BC, even though it has some limitations, including immobility, ionizing radiation, and patient weight restrictions. The aim of the study was to evaluate the correlations of BC parameters measured by bioelectrical impedance analysis (BIA) with those measured by DEXA in patients with MASLD and HTN. Methods: Overall, 78 patients with MASLD and HTN underwent the following study procedures: compilation of an anamnesis, physical examination of a patient, laboratory tests, abdominal ultrasound, BIA, DEXA, and anthropometric measurements. Results: The agreement between BIA and DEXA in diagnosing reduced skeletal muscle mass (SMM) in patients with MASLD and HTN was moderate (kappa values were 0.440 and 0.404 in males and females, respectively). Significant strong direct correlations were found between fat mass (FM) and body fat percentage measured by BIA with corresponding measurements by DEXA (p < 0.001 for both). The area under the receiver operating characteristic curves (AUC) of SMM to body weight ratios calculated using BIA data were 0.834 and 0.929 for reduced appendicular SMM determined by DEXA in males and females with MASLD and HTN, respectively. Conclusions: In conclusion, BIA is an easy-to-use and widely available tool for assessing SMM and FM in patients with MASLD and HTN, demonstrating reliable agreement with DEXA measurement results and completely free of its limitations. Full article
(This article belongs to the Section Medical Imaging and Theranostics)
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<p>Receiver operating characteristic (ROC) curve for SMM/W ratio to exclude decreased ASMM/W index values measured by DEXA in female patients with MASLD and HTN. The area under the ROC curve (AUC) ± standard errors (SE) for SMM/W ratio was 0.834 ± 0.061; 95% confidence interval (CI): 0.715–0.954.</p>
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<p>Receiver operating characteristic (ROC) curve for SMM/W ratio to confirm the presence of decreased ASMM/W index values measured by DEXA in male patients with MASLD and HTN. The area under the ROC curve (AUC) ± standard errors (SE) for SMM/W ratio was 0.929 ± 0.032; 95% CI: 0.865–0.992.</p>
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20 pages, 27208 KiB  
Article
Optimization of Organic Rankine Cycle for Hot Dry Rock Power System: A Stackelberg Game Approach
by Zhehao Hu, Wenbin Wu and Yang Si
Energies 2024, 17(20), 5151; https://doi.org/10.3390/en17205151 - 16 Oct 2024
Viewed by 250
Abstract
Due to its simple structure and stable operation, the Organic Rankine Cycle (ORC) has gained significant attention as a primary solution for low-grade thermal power generation. However, the economic challenges associated with development difficulties in hot dry rock (HDR) geothermal power systems have [...] Read more.
Due to its simple structure and stable operation, the Organic Rankine Cycle (ORC) has gained significant attention as a primary solution for low-grade thermal power generation. However, the economic challenges associated with development difficulties in hot dry rock (HDR) geothermal power systems have necessitated a better balance between performance and cost effectiveness within ORC systems. This paper establishes a game pattern of the Organic Rankine Cycle with performance as the master layer and economy as the slave layer, based on the Stackelberg game theory. The optimal working fluid for the ORC is identified as R600. At the R600 mass flow rate of 50 kg/s, the net system cycle work is 4186 kW, the generation efficiency is 14.52%, and the levelized cost of energy is 0.0176 USD/kWh. The research establishes an optimization method for the Organic Rankine Cycle based on the Stackelberg game framework, where the network of the system is the primary optimization objective, and the heat transfer areas of the evaporator and condenser serve as the secondary optimization objective. An iterative solving method is utilized to achieve equilibrium between the performance and economy of the ORC system. The proposed method is validated through a case study utilizing hot dry rock data from Qinghai Gonghe, allowing for a thorough analysis of the working fluid and system parameters. The findings indicate that the proposed approach effectively balances ORC performance with economic considerations, thereby enhancing the overall revenue of the HDR power system. Full article
(This article belongs to the Special Issue Big Data Analysis and Application in Power System)
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<p>ORC system flowchart.</p>
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<p>Schematic diagram of Stackelberg game pattern for ORC system optimization.</p>
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<p>Shell and tube heat exchanger geometry.</p>
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<p>Schematic diagram of heat exchange process of evaporator.</p>
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<p>Schematic diagram of tube bundle arrangement.</p>
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<p>Schematic diagram of condenser heat exchange process.</p>
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<p>ORC system optimization Stackelberg game approach.</p>
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<p>Optimal network of organic working fluids.</p>
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<p>Minimum heat transfer area per kW for organic working fluids.</p>
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<p>Levelized cost of energy for organic working fluids.</p>
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<p>Relationship between tube bundle arrangement and heat transfer area.</p>
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18 pages, 321 KiB  
Article
Re-Imagining Trade Policy and Energy Efficiency: Groundbreaking Pathways to Strengthen Environmental Sustainability in South Korea
by Dongxue Wang and Yugang He
Appl. Sci. 2024, 14(20), 9443; https://doi.org/10.3390/app14209443 - 16 Oct 2024
Viewed by 421
Abstract
This study explores the long-term interplay between trade policy, energy efficiency, and carbon dioxide (CO2) emissions in South Korea, using data spanning from 1985 to 2023. By applying the Fourier autoregressive distributed lag (FARDL) model, the analysis reveals that while trade [...] Read more.
This study explores the long-term interplay between trade policy, energy efficiency, and carbon dioxide (CO2) emissions in South Korea, using data spanning from 1985 to 2023. By applying the Fourier autoregressive distributed lag (FARDL) model, the analysis reveals that while trade liberalization initially leads to a 0.23% increase in CO2 emissions for each 1% rise in trade openness—driven by the energy demands of industrial expansion—integrating energy efficiency standards within trade agreements helps mitigate these effects over time; this results in a 0.26% reduction in emissions for every 1% improvement in energy efficiency. The study also highlights the dual role of foreign direct investment (FDI), which contributes to a short-term 0.08% rise in emissions but significantly reduces carbon intensity in the long term by facilitating the adoption of cleaner technologies. These findings underscore the importance of innovation and FDI in decoupling economic growth from environmental degradation. The study advocates for the incorporation of energy efficiency measures into trade agreements and the prioritization of green technologies, recommending strategies that could enable South Korea to reduce its CO2 emissions by up to 40% by 2030. This research positions South Korea as a key actor in achieving global climate goals while maintaining economic competitiveness, offering valuable insights into the balance between sustainable development and industrial growth. Full article
9 pages, 534 KiB  
Article
Energy Availability and Body Composition in Professional Athletes: Two Sides of the Same Coin
by Roberto Palazzo, Tommaso Parisi, Sara Rosa, Marco Corsi, Edoardo Falconi and Laura Stefani
Nutrients 2024, 16(20), 3507; https://doi.org/10.3390/nu16203507 - 16 Oct 2024
Viewed by 250
Abstract
Background/Objectives: Energy availability (EA) is essential for maintaining physiological functions, significantly influencing athletes’ health and performance. Nutritional behaviors, however, vary across sports. This study aims to assess EA levels in athletes from different disciplines, focusing on the relationship between EA and body composition [...] Read more.
Background/Objectives: Energy availability (EA) is essential for maintaining physiological functions, significantly influencing athletes’ health and performance. Nutritional behaviors, however, vary across sports. This study aims to assess EA levels in athletes from different disciplines, focusing on the relationship between EA and body composition in endurance athletes compared to rugby players. Methods: This study involved 18 endurance athletes (15 men, 3 women) and 36 rugby players (all men). Data were gathered through interviews, questionnaires, and bioimpedance analysis. Energy intake (EI) was measured with a 24 h dietary recall, and exercise energy expenditure (EEE) was calculated using the IPAQ questionnaire. EA was calculated as EA = (EI − EEE)/fat-free mass (FFM), with results categorized into clinical, subclinical, and optimal ranges. Results: The endurance group had a lower average FFM (57.81 kg) compared to the rugby players (67.61 kg). EA was also significantly lower in endurance athletes (11.72 kcal/kg FFM) than in rugby players (35.44 kcal/kg FFM). Endurance athletes showed more restrictive nutritional behavior with lower EI and higher EEE, but both groups maintained body composition within normal ranges. Conclusions: Endurance athletes exhibit greater nutritional restrictions compared to rugby players, though their body composition remains healthy. Further research is required to investigate the long-term effects of low EA on performance, injury risk, and potential impairment when EA falls below the optimal threshold of 45 kcal/kg FFM/day. Full article
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<p>(<b>A</b>,<b>B</b>) representing the EA levels in endurance athletes (E) and in rugby players (R), respectively. In E athletes, no optimal EA was observed, while in R players, the majority were within the subclinical and optimal range.</p>
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<p>Comparison of average EI, EEE, and EA levels in the two groups of athletes.</p>
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19 pages, 6139 KiB  
Article
Estimation of Regional Electricity Consumption Using National Polar-Orbiting Partnership’s Visible Infrared Imaging Radiometer Suite Night-Time Light Data with Gradient Boosting Regression Trees
by Xiaozheng Guo and Yimei Wang
Remote Sens. 2024, 16(20), 3841; https://doi.org/10.3390/rs16203841 - 16 Oct 2024
Viewed by 238
Abstract
With the rapid development of society and economy, the growth of electricity consumption has become one of the important indicators to measure the level of regional economic development. This paper utilizes NPP-VIIRS nighttime light remote sensing data to model electricity consumption in parts [...] Read more.
With the rapid development of society and economy, the growth of electricity consumption has become one of the important indicators to measure the level of regional economic development. This paper utilizes NPP-VIIRS nighttime light remote sensing data to model electricity consumption in parts of southern China. Four predictive models were initially selected for evaluation: LR, SVR, MLP, and GBRT. The accuracy of each model was assessed by comparing real power consumption with simulated values. Based on this evaluation, the GBRT model was identified as the most effective and was selected to establish a comprehensive model of electricity consumption. Using the GBRT model, this paper analyzes electricity consumption in the study area across different spatial scales from 2013 to 2022, demonstrating the distribution characteristics of electricity consumption from the pixel level to the city scale and revealing the close relationship between electricity consumption and regional economic development. Additionally, this paper examines trends in electricity consumption across various temporal scales, providing a scientific basis for the optimal allocation of energy and the effective distribution of power resources in the study area. This analysis is of great significance for promoting balanced economic development between regions and enhancing energy efficiency. Full article
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<p>The map of the location and elevation of the study area.</p>
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<p>Flowchart of the methodology.</p>
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<p>Scatter plot of actual electricity consumption vs. simulated electricity consumption using four different models: (<b>a</b>) LR, (<b>b</b>) SVR, (<b>c</b>) MLP, and (<b>d</b>) GBRT.</p>
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<p>Distribution characteristics of electricity consumption at the grid scale in the study area from 2013 to 2022.</p>
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<p>Distribution characteristics of electricity consumption at the city scale in the study area from 2013 to 2022.</p>
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<p>Annual power consumption at provincial level in the study area from 2013 to 2022.</p>
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<p>The average of monthly electricity consumption at the provincial level in the study area from 2013 to 2022.</p>
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<p>Distribution characteristics of electricity consumption in Nanning and Fuzhou in 2013 and 2022.</p>
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<p>Distribution characteristics of electricity consumption in Shenzhen and Guangzhou in 2013 and 2022.</p>
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<p>Annual electricity consumption in typical cities in the study area from 2013 to 2022.</p>
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22 pages, 14941 KiB  
Article
Profiling of Key Hub Genes Using a Two-State Weighted Gene Co-Expression Network of ‘Jao Khao’ Rice under Soil Salinity Stress Based on Time-Series Transcriptome Data
by Prasit Khunsanit, Kitiporn Plaimas, Supachitra Chadchawan and Teerapong Buaboocha
Int. J. Mol. Sci. 2024, 25(20), 11086; https://doi.org/10.3390/ijms252011086 (registering DOI) - 16 Oct 2024
Viewed by 274
Abstract
RNA-sequencing enables the comprehensive detection of gene expression levels at specific time points and facilitates the identification of stress-related genes through co-expression network analysis. Understanding the molecular mechanisms and identifying key genes associated with salt tolerance is crucial for developing rice varieties that [...] Read more.
RNA-sequencing enables the comprehensive detection of gene expression levels at specific time points and facilitates the identification of stress-related genes through co-expression network analysis. Understanding the molecular mechanisms and identifying key genes associated with salt tolerance is crucial for developing rice varieties that can thrive in saline environments, particularly in regions affected by soil salinization. In this study, we conducted an RNA-sequencing-based time-course transcriptome analysis of ‘Jao Khao’, a salt-tolerant Thai rice variety, grown under normal or saline (160 mM NaCl) soil conditions. Leaf samples were collected at 0, 3, 6, 12, 24, and 48 h. In total, 36 RNA libraries were sequenced. ‘Jao Khao’ was found to be highly salt-tolerant, as indicated by the non-significant differences in relative water content, cell membrane stability, leaf greenness, and chlorophyll fluorescence over a 9-day period under saline conditions. Plant growth was slightly retarded during days 3–6 but recovered by day 9. Based on time-series transcriptome data, we conducted differential gene expression and weighted gene co-expression network analyses. Through centrality change from normal to salinity network, 111 key hub genes were identified among 1,950 highly variable genes. Enriched genes were involved in ATP-driven transport, light reactions and response to light, ATP synthesis and carbon fixation, disease resistance and proteinase inhibitor activity. These genes were upregulated early during salt stress and RT-qPCR showed that ‘Jao Khao’ exhibited an early upregulation trend of two important genes in energy metabolism: RuBisCo (LOC_Os10g21268) and ATP synthase (LOC_Os10g21264). Our findings highlight the importance of managing energy requirements in the initial phase of the plant salt-stress response. Therefore, manipulation of the energy metabolism should be the focus in plant resistance breeding and the genes identified in this work can serve as potentially effective candidates. Full article
(This article belongs to the Special Issue Abiotic Stress Tolerance and Genetic Diversity in Plants, 2nd Edition)
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<p>Comparison of phenotypic traits between normal and saline conditions of ‘Jao Khao’. (<b>A</b>) tiller number, (<b>B</b>) SES, (<b>C</b>) shoot fresh weight, (<b>D</b>) root fresh weight, (<b>E</b>) shoot dry weight, (<b>F</b>) root dry weight, (<b>G</b>) shoot dry-to-fresh weight ratio, (<b>H</b>) root dry-to-fresh weight ratio, (<b>I</b>) CMS, and (<b>J</b>) RWC. Data are presented as means ± SD (n = 3). Statistical significance was determined using the Duncan multiple range test. Significant differences (<span class="html-italic">p</span> ≤ 0.05) are indicated by different letters. ns: not significant.</p>
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<p>Leaf greenness and chlorophyll fluorescence of ‘Jao Khao’ compared between that of control and salt conditions. (<b>A</b>) SPAD index, (<b>B</b>) Maximum PSII efficiency (Fv/Fm), and (<b>C</b>) Performance index (Pi). Data are presented as means ± SD (n = 3). Statistical significance was determined using the Duncan multiple range test. Significant differences (<span class="html-italic">p</span> ≤ 0.05) are indicated by different letters. ns: not significant.</p>
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<p>Normalized read counts of 36 RNA-sequencing library (<b>A</b>), scale-free topology and mean connectivity (the horizontal red line was at <span class="html-italic">R</span><sup>2</sup> = 0.9) (<b>B</b>), the heatmap of topological overlapping matrix (TOM) plot visualizing the strength of the connections (similarity) between genes with the bright yellow color indicating genes with more connections or shared neighbors in the network and the colors representing modules displayed on both axes (<b>C</b>), and module–trait relationships (MTR) (<b>D</b>). The colors of modules include blue, red, turquoise, green, brown, yellow and grey. The letters ct and ss indicate control conditions and salt stress conditions, respectively. ME: Module Eigengene, a representative of gene expression levels in a cluster of co-expressed genes. Significant differences (<span class="html-italic">p</span> ≤ 0.05) are indicated by *.</p>
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<p>Comparison of the distribution of centrality between the normal-state and saline-state networks for (<b>A</b>) degree, (<b>B</b>) closeness, (<b>C</b>) betweenness, and (<b>D</b>) the clustering coefficient.</p>
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<p>Gene Ontology (GO) enrichment analysis results for each module. <span class="html-italic">p</span>-values were adjusted using the Benjamini–Hochberg correction. (<b>A</b>) Brown module, (<b>B</b>) turquoise module, (<b>C</b>) yellow module, (<b>D</b>) blue module, (<b>E</b>) red module, and (<b>F</b>) green module. GO terms include biological process (BP), cellular component (CC), and molecular function (MF).</p>
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<p>Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment results for each module. <span class="html-italic">p</span>-values were adjusted using the Benjamini–Hochberg correction.</p>
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<p>Gene networks and key genes were identified based on the centrality change between the two states (normal and saline) and mapped to the global state network. (<b>A</b>) Brown module, (<b>B</b>) turquoise module, (<b>C</b>) yellow module, (<b>D</b>) blue module, (<b>E</b>) red module, (<b>F</b>) green module, and (<b>G</b>) grey module. Small nodes and edges are colored according to the module they belong to. Large nodes represent key genes detected based on DG, BW, CN, and CC centrality, with combinations of 1, 2, 3, and 4 centrality measures, which are indicated in bright colors: green, blue, orange, and red, respectively.</p>
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<p>Relative expression levels (fold change) of two genes involved in energy metabolism: <span class="html-italic">LOC_Os10g21268</span> and <span class="html-italic">LOC_Os10g21264</span> in three varieties: ‘Jao Khao’ (<b>A</b>,<b>D</b>), ‘Pokkali’ (<b>B</b>,<b>E</b>), and ‘IR29’ (<b>C</b>,<b>F</b>) grown under salt stress conditions relative to those under control conditions by RT-qPCR. Data are presented as means ± SD (<span class="html-italic">n</span> = 3). Statistical significance was determined using the Duncan multiple range test. Significant differences (<span class="html-italic">p</span> ≤ 0.05) are indicated by different letters.</p>
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<p>Proposed mechanism of salt stress responses in ‘Jao Khao’ rice as inferred from a comprehensive analysis of time-course transcriptome data. Names bordered by colored lines are key genes. Transcription factors are shown in red letters. GO enrichment analysis revealed several GO terms related to key plant energy metabolism processes, such as light reactions, carbon fixation, and ATP synthesis. Many genes associated with these GO terms exhibited increased expression under salt stress. These enriched processes indicate the importance of maintaining energy production early during salt stress to regulate ion and water uptake and transport. Other enriched GO terms suggested the involvement of ATP-driven transport and the ubiquitination-proteasome pathway in responses to salt stress. Several candidate transcription factors, including <span class="html-italic">bZIP46</span>, <span class="html-italic">SPL4</span>, <span class="html-italic">ASR5</span>, and the transcriptional corepressor LEUNIG, may coordinate these processes. Dash-arrows and question marks suggest potential regulatory relationships.</p>
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<p>Diagram illustrating the co-expression network analysis pipeline used in the present study.</p>
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19 pages, 10729 KiB  
Article
Experimental Study on Human Kinetic Energy Harvesting with Wearable Lifejackets to Assist Search and Rescue
by Jeffrey To and Loulin Huang
Electronics 2024, 13(20), 4059; https://doi.org/10.3390/electronics13204059 (registering DOI) - 15 Oct 2024
Viewed by 259
Abstract
This study explores the integration of a human kinetic energy-harvesting mechanism into lifejackets to address the energy needs of aid search and rescue operations in aquatic environments. Due to the limited data on the movement patterns of drowning individuals, a human motion model [...] Read more.
This study explores the integration of a human kinetic energy-harvesting mechanism into lifejackets to address the energy needs of aid search and rescue operations in aquatic environments. Due to the limited data on the movement patterns of drowning individuals, a human motion model has been developed to identify optimal design parameters for energy harvesting. This model is developed from computer vision analysis of underwater footage and motion capture laboratory experiments and is used to quantify the potential for power generation. The field testing experiment is conducted underwater, replicating the environment used for footage collection and analysis for the modelling. During the field testing, the participant wears a lifejacket integrated with the energy-harvesting device. Field testing data are then collected to verify the model. The efficacy of this approach is demonstrated with observed power outputs ranging from 0 mW to 754 mW in simulations and experiments. Despite challenges such as the “dead zone” in a drowning person’s motion, the success of the experiments underscores the potential of the proposed energy-harvesting mechanism to efficiently harness the kinetic energy generated by a drowning person’s movements. This study contributes to the development of sustainable, energy-efficient solutions for search and rescue operations, particularly in remote and challenging aquatic environments. Full article
(This article belongs to the Special Issue Energy Harvesting and Energy Storage Systems, 3rd Edition)
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<p>Conceptual design where the energy harvester is located at the waist strap of the lifejacket.</p>
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<p>Specification details of YG2734 12 V motor [<a href="#B15-electronics-13-04059" class="html-bibr">15</a>].</p>
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<p>Circuit diagram for the experiment’s prototype.</p>
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<p>Circuit diagram consideration for the DC motor as the energy harvester of the future.</p>
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<p>Dynamic model of human performing ladder-climbing motion.</p>
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<p>Illustration of the fluid forces acting on the truncated elliptical cone—limb.</p>
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<p>Body segments for motion analysis.</p>
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<p>A sketch of the harvesting system with the ideal position of the energy harvester.</p>
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<p>Transmission diagram of the energy-harvesting system.</p>
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<p>Screenshot from the underwater video with computer vision and MediaPipe analysis.</p>
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<p>Sample of some of the data collected from the experiment where Point No. 24 is the hip joint and Point No. 26 is the knee joint.</p>
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<p>The hip angle changes over time during the ladder-climbing motion.</p>
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<p>The angular speed of the hip angle during the ladder-climbing motion.</p>
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<p>Energy harvester position and angular velocity calculation.</p>
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<p>Energy harvester angular velocity vs. hip joint angular velocity—computer vision.</p>
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<p>Power output from Matlab calculation with electrical load using computer vision data.</p>
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<p>Circuit diagram of the energy harvester [<a href="#B22-electronics-13-04059" class="html-bibr">22</a>,<a href="#B23-electronics-13-04059" class="html-bibr">23</a>].</p>
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<p>Energy harvester prototype.</p>
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<p>Power (mW) vs. time (s).</p>
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<p>Bus voltage (V) vs. time (s).</p>
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<p>Shunt voltage (V) vs. time (s).</p>
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<p>Load voltage (V) vs. time (s).</p>
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<p>Current (mA) vs. time (s).</p>
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<p>Energy harvested in Matlab simulation.</p>
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