bluuebunny/crossref_metadata_2025 huggingface dataset:
Augmenting Residential AC Electric Water Heating with Dedicated Direct-to-Element DC Solar Photovoltaic
Authors: Pfister Daniel , Rix Arnold Johan , Booysen Marthinus Johannes
Published: February 2025

Residential water heating represents one of the most energy-intensive household applications, particularly in South Africa, where immersed resistive element heating dominates. Solar photovoltaic systems provide a promising solution for augmenting grid-based electrical water heaters, offering energy cost savings and environmental benefits. This study evaluates a novel approach to integrate solar photovoltaic directly into electrical water heater systems without using inverters. Using a combination of field experiments and simulation, four heating strategies were assessed, namely: “grid only”, “solar medium”, “solar heavy”, and “solar timer”. Metrics such as solar augmentation ratio, solar utilization, and cold event frequency were analyzed for different seasons using real-world and simulated water usage profiles. Results demonstrate significant grid energy reductions through solar augmentation, particularly in warmer seasons. However, the effectiveness of the strategies varies, with increased solar utilization often correlated with a higher frequency of cold events. A hybrid seasonal strategy is proposed to optimize energy savings while maintaining user comfort. This work highlights the potential of direct DC solar photovoltaic integration as a cost-effective and sustainable enhancement for residential water heating.
Capacity Optimization Configuration of Hybrid Energy Storage Systems for Wind Farms Based on Improved k-means and Two-Stage Decomposition
Authors: Zhang Xi , Kang Longyun , Wang Xuemei , Liu Yangbo , Huang Sheng
Published: February 2025

To address the issue of excessive grid-connected power fluctuations in wind farms, this paper proposes a capacity optimization method for a hybrid energy storage system (HESS) based on wind power two-stage decomposition. First, considering the susceptibility of traditional k-means results to initial cluster center positions, the k-means++ algorithm was used to cluster the annual wind power, with the optimal number of clusters determined by silhouette coefficient and Davies–Bouldin Index. The overall characteristics of each cluster and the cumulative fluctuations were considered to determine typical daily data. Subsequently, improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) was used to decompose the original wind power data for typical days, yielding both the grid-connected power and the HESS power. To leverage the advantages of power-type and energy-type storage while avoiding mode aliasing, the improved pelican optimization algorithm—variational mode decomposition (IPOA-VMD) was applied to decompose the HESS power, enabling accurate distribution of power for different storage types. Finally, a capacity optimization model for a HESS composed of lithium batteries and supercapacitors was developed. Case studies showed that the two-stage decomposition strategy proposed in this paper could effectively reduce grid-connected power fluctuations, better utilize the advantages of different energy storage types, and reduce HESS costs.
Renewable and Sustainable Energy—Current State and Prospects
Authors: Igliński Bartłomiej , Pietrzak Michał Bernard
Published: February 2025

The energy transition is seen as a fundamental engine of economic development and a factor in improving the quality of life [...]
Research on the Safety Risk Analysis Framework and Control System for Multi-Type New Energy Storage Technologies
Authors: Lian Ningning , Ji Wentao , Chen Jie
Published: February 2025

In the context of the global energy landscape restructuring driven by the “dual-carbon” goals, new energy storage technologies have emerged as a critical enabler for energy transformation and the development of a new power system. However, as these technologies advance and the market expands, ensuring safety remains a significant and long-term challenge. This paper focuses on the safety risk prevention and control of new energy storage systems. It systematically reviewed various new energy storage technology pathways and their associated potential risks. Furthermore, it analyzed the challenges and difficulties faced in safety risk prevention and control across different stages of new energy storage projects, including large-scale application, pilot demonstration, and R&D reserves. Considering the technical uncertainties in the future development of new energy storage, this study evaluated potential safety risks and proposed corresponding strategies and measures for risk management. By addressing these challenges, this study aims to safe-guard the security and reliability of new energy storage technologies, thereby supporting the construction of a robust and sustainable new power system.
Risk Assessment of High-Voltage Power Grid Under Typhoon Disaster Based on Model-Driven and Data-Driven Methods
Authors: Zhou Xiao , Li Jiang
Published: February 2025

As global warming continues to intensify, typhoon disasters will more frequently occur in East and Southeast Asia, posing a high risk of causing large-scale power outages in the power system. To investigate the impact of typhoon disasters on high-voltage power grids, a comprehensive risk assessment method that integrates model-driven and data-driven approaches is proposed, which can predict power grid faults in advance and provide support for power grid operators to generate emergency dispatching plans. Firstly, by comparing actual loads with the design strengths of the transmission tower-line system and analyzing the geometric relationship between typhoon wind circles and the system, key variables, such as wind speed, longitude, latitude, and other pertinent factors, are screened. The Spearman correlation coefficient is employed to pinpoint the meteorological variables that exhibit a high degree of relevance, enhancing the accuracy and interpretability of our model. Secondly, addressing the lack of power grid fault samples, three data balancing methods—Borderline-SMOTE, ADASYN, and SMOTE-Tomek—are compared, with Borderline-SMOTE selected for its superior performance in enhancing the sample set. Additionally, a power grid failure risk assessment model is built based on Light Gradient Boosting Machine (LightGBM), and the Borderline-Smoothing Algorithm (BSA) is used for the modeling of power grid faults. The nonlinear mapping relationship between typhoon meteorological data and the power grid equipment failure rate is extracted through deep learning training. Subsequently, the Tree-structured Parzen Estimator (TPE) is leveraged to optimize the hyperparameters of the LightGBM model, thus enhancing its prediction accuracy. Finally, the actual power system data of a province in China under a strong typhoon are assessed, validating the proposed assessment method’s effectiveness.
Sustainable Geothermal Energy: A Review of Challenges and Opportunities in Deep Wells and Shallow Heat Pumps for Transitioning Professionals
Authors: Elshehabi Tawfik , Alfehaid Mohammad
Published: February 2025

Geothermal energy has emerged as a cornerstone in renewable energy, delivering reliable, low-emission baseload electricity and heating solutions. This review bridges the current knowledge gap by addressing challenges and opportunities for engineers and scientists, especially those transitioning from other professions. It examines deep and shallow geothermal systems and explores the advanced technologies and skills required across various climates and environments. Transferable expertise in drilling, completion, subsurface evaluation, and hydrological assessment is required for geothermal development but must be adapted to meet the demands of high-temperature, high-pressure environments; abrasive rocks; and complex downhole conditions. Emerging technologies like Enhanced Geothermal Systems (EGSs) and closed-loop systems enable sustainable energy extraction from impermeable and dry formations. Shallow systems utilize near-surface thermal gradients, hydrology, and soil conditions for efficient heat pump operations. Sustainable practices, including reinjection, machine learning-driven fracture modeling, and the use of corrosion-resistant alloys, enhance well integrity and long-term performance. Case studies like Utah FORGE and the Geysers in California, US, demonstrate hydraulic stimulation, machine learning, and reservoir management, while Cornell University has advanced integrated hybrid geothermal systems. Government incentives, such as tax credits under the Inflation Reduction Act, and academic initiatives, such as adopting geothermal energy at Cornell and Colorado Mesa Universities, are accelerating geothermal integration. These advancements, combined with transferable expertise, position geothermal energy as a major contributor to the global transition to renewable energy.
Experimental Investigation of Deposition of Silica Nanocolloids by Depressurizing Supercritical Water Vapor
Authors: Bordvik Silje , Tjelta Morten , Næss Erling
Published: February 2025

This article presents the results of an experimental investigation of silica deposition from depressurized supercritical steam. The case investigated is relevant for supercritical geothermal reservoirs with high temperature and pressure, where silica content is significant and deposition occurs rapidly upon depressurization. The purpose of the presented experiments is to accurately measure the deposited mass in two different areas in a flow tube and mathematically relate the measurement to particle formation behavior. In addition, SEM analysis permits valuable insight into the morphology of the scale formed under these conditions. The measured deposition is caused by silica solids formed when depressurizing supercritical fluids from around 350 bar and 500 °C by an isenthalpic valve to a state of superheated steam and pressures ranging from 60 to 150 bar. A test rig was designed, fabricated, and used for this purpose. The deposition mechanisms differ from silica particle formation in the water phase and the limited experimental research for the investigated conditions makes the gathered data highly interesting. The measured results are compared to validated models for deposition in straight pipes. The knowledge obtained on silica solidification and deposition can be used to optimize steam treatment of high-temperature pressurized geothermal sources for maximum power utilization by aiding in the development of advanced prediction tools for scaling and mineral extraction.
Load Frequency Control Based on Gray Wolf Optimizer Algorithm for Modern Power Systems
Authors: Tuan Dao Huy , Tran Dao Trong , Nguyen Ngoc Thanh Van , Huynh Van Van
Published: February 2025

The increasing complexity of modern power systems (MPSs), driven by the integration of renewable energy sources and multi-area configurations, demands robust and adaptive load frequency control (LFC) strategies. This paper proposes a novel approach to the LFC of the MPS by integrating a proportional–integral–derivative (PID) controller optimized using the gray wolf optimizer (GWO) algorithm. The effectiveness of the GWO-PID method is evaluated on multi-area power systems, including systems integrated with wind energy. The GWO-PID controller shows superior frequency stability, achieving deviations of 49.67 Hz, 49.68 Hz, 49.87 Hz, 49.87 Hz and 49.88 Hz for area 1 and area 2 of the two-area multisource MPS, as well as for area 1, area 2 and area 3 in the three-area multisource MPS. The results demonstrate significant improvements in frequency stabilization, reduced oscillations and enhanced steady-state accuracy compared to traditional optimization techniques. This study emphasizes the scalability and adaptability of the proposed method to changing load conditions and complexity of the MPSs, providing a potential solution to ensure stability and reliability for the MPSs.
Performance Evaluation of a Combined Heat and Power Generation System with Borehole Thermal Energy Storage: A Feasibility Study of a Combined Heat Pump and Organic Rankine Cycle System
Authors: Mudasar Roshaan , Leong Wey H.
Published: February 2025

The current research is focused on the introduction of a heat pump (HP)-assisted organic Rankine cycle (ORC), which runs on the heat extracted from a high-temperature borehole thermal energy storage (BTES). By varying different source temperatures from 40 °C to 60 °C, the HP cycle works to upgrade the heat to run the ORC. Different combinations of environmentally friendly fluids are studied in comparison to match the top and bottom cycles and to make the overall system a combined heat and power (CHP) system. A power sufficiency condition is defined to compare and identify the best working fluid combination for the HP cycle and ORC. Based on the analysis, ammonia for the HP and R1234zee for the ORC emerged to be a suitable combination among all the studied combinations. As an example, for a BTES heat source of 237 kW at the source temperature of 60 °C, the BTES–HP–ORC–district heating system with the ammonia–R1234zee pair has resulted in the HP compressor work input of 21.9 kW with the coefficient of performance (COP) of 10.9 for the HP cycle and the ORC net work output and district heating supply of 10.4 kW and 209 kW, respectively, with the thermal efficiency (η) of 4.3% for the ORC at the evaporation temperature of 65 °C. A study in terms of the greenhouse gas (GHG) emissions reveals the feasibility of the system depending on the regional GHG intensity and emission factor of electricity and natural gas.
Biofuel Production from Phytoremediated Biomass via Various Conversion Routes: A Review
Authors: Bao Chengjia , Cao Yi , Zhao Long , Li Xiaojuan , Zhang Jing , Mao Chunlan
Published: February 2025

Phytoremediation is recognized as a highly cost-effective technique for remediating soils contaminated with heavy metals (HMs). Biomass residues from these remediated plants constitute a significant resource with considerable potential for biofuel conversion. However, the potential of these residues for biofuel production has not been extensively reviewed. This review aims to comprehensively review the recent progress in converting phytoremediated biomass into biofuels via various pathways. Methods for the disposal and biofuel conversion of residual phytoremediated biomass are summarized. The advantages and limitations of the different techniques are discussed and compared. These residues can be converted into gaseous (biogas/methane), liquid (biodiesel, bioethanol, and bio-oil), or solid energy forms (biochar, hydrochar). The conversion methods reviewed include anaerobic digestion, nanomaterial synthesis, incineration, gasification, and pyrolysis. HMs such as copper, cadmium, and zinc significantly influence these processes, enhancing them at lower concentrations but inhibiting them at higher concentrations. However, these conversion routes often involve high costs and complex operational conditions, and are typically limited to laboratory-scale, short-term trials. Therefore, there is an urgent need for multi-objective strategies that consider economic factors, viability, scalability, and environmental sustainability through sustainable pathways. Proper treatment of phytoremediated biomass with energy recovery presents an economically viable and environmentally sustainable solution.
The Influence of Electrode Shape on the Electric and Temperature Fields in an Immersed High-Voltage Electrode Boiler
Authors: Wang Mingyong , Wang Jianfei , Zhang Yiling , Li Lu , Zhou Wenkai , Lei Zhipeng
Published: February 2025

The electric and temperature fields formed in the furnace water system by electrodes of different shapes differ to some extent when the immersed high-voltage electrode boiler is in operation. To obtain the distribution of electric and temperature fields in the furnace water when different shapes of electrodes are used in a high-voltage electrode boiler, simulation models of spherical electrodes, planar electrodes, and tangential electrodes are established, respectively. The effects of the electrode structure on the electric and temperature fields in the furnace water were investigated. The simulation results show that the electric field distribution and temperature field distribution of the spherical electrode in the furnace water are the best among the three electrode structures. Meanwhile, in order to verify the accuracy of the adopted simulation method, simulation and temperature rise tests were carried out on a small spherical electrode model under 400 V AC, and the simulation calculation results and the temperature rise test results at special points were compared. The difference between the simulation and test results is less than 3%, which proves the reasonableness of the method. The method can be used as a reference for the design of electrodes for immersed high-voltage electrode boilers, as well as the analysis of electric and temperature fields around the electrodes.
Coordinated Optimization Method of Electric Buses and Voltage Source Converters for Improving the Absorption Capacity of New Energy Sources and Loads in Distribution Networks
Authors: Liu Yang , Huang Min , Zhang Yujing , Zhang Lu , Liu Wenbin , Yu Haidong , Wang Feng , Li Lisheng
Published: February 2025

The large-scale integration of renewable energy sources and new loads, such as distributed photovoltaics and electric vehicles, has resulted in frequent power quality issues within distribution networks. Traditional AC distribution networks lack the necessary flexibility and have limited capacity to accommodate these new energy sources and loads. Transforming the conventional distribution network into an AC-DC hybrid network using flexible interconnection devices like Voltage Source Converters can enhance the network’s flexibility, mitigating the power quality challenges arising from the integration of renewable energy and new loads. Electric buses, with their substantial capacity, mobility, and centralized management, offer potential as mobile energy storage. They can participate in the dispatching of the distribution network, thereby improving the network’s flexibility in power regulation. This paper proposes a coordinated optimization approach that integrates electric buses and VSCs for distribution network dispatch. This method enables electric buses to assist in power dispatch without interfering with their primary public transport duties, thus enhancing the network’s capacity to absorb new energy sources and loads. Firstly, considering the mobility characteristics of electric buses, a multi-layer stochastic Time–Space Network model is developed for bus dispatching. Secondly, an optimization model is constructed that accounts for the coordination of charging and discharging power between VSCs and electric buses, with the objective of minimizing the network losses in the distribution system. Finally, the proposed model is transformed into a second-order cone programming formulation, facilitating its solution through convex optimization techniques. The effectiveness of the proposed approach is demonstrated through a case study.
Study on the Effect of Mineral Compounds on the Behavior of Heavy Metals During Oily Sludge Incineration
Authors: Han Yue , Gong Zhiqiang , Xu Mingxin
Published: February 2025

Incineration is a highly effective method for treating oily sludge. However, during the incineration process, heavy metals may either be released into the air via flue gas or remain in the bottom ash in an unstable form, posing significant environmental threats. Mineral compounds can provide adsorption sites for heavy metals and promote the stable existence of heavy metals in incineration bottom ash. In this paper, the incineration experiments of oily sludge with CaO, Fe2O3, Al2O3 and MgO were conducted using a horizontal tube furnace. The total amount, leaching characteristics, and morphological distribution of heavy metals in the obtained incineration bottom ash were analyzed. The results showed that CaO had a significant adsorption effect on Cu, Cr, Pb, As and Cd. Al2O3 exhibited the best leaching inhibition effect on Cr, Zn, Pb, As, and Cd. The influence of mineral compounds on the morphological distribution of heavy metals during incineration was highly dependent on the type of metal. This work will provide crucial theoretical support for the source control of heavy metals during oily sludge incineration and hold important practical significance for achieving the harmless treatment of oily sludge and promoting the development of oily sludge incineration technology.
An Investigation of Operational Challenges in MHz Power Converters
Authors: Hussain Aqarib , Boland Andrew , Varner Regan , Matolak David , Booth Kristen
Published: February 2025

Megahertz switching frequencies in converters significantly reduce the size of passive components, enabling high power density. However, these frequencies also introduce operational challenges, such as the semiconductor device reliability, thermal management, magnetic design and electromagnetic interference. This paper discusses a dc-dc converter operating at 1 MHz and its associated design challenges. The relationship between a GaN device on-resistance, junction temperature and losses in scenarios where the converter operates beyond its nominal design specifications is analyzed. Additionally, a PCB-based inductor is fully characterized and the parasitic effects of PCB traces are examined for a 1-MHz, 1-kW application. Finally, the conducted and radiated emissions of the converter are addressed, supported by simulation and hardware experimental measurements.
Advancing AI-Enabled Techniques in Energy System Modeling: A Review of Data-Driven, Mechanism-Driven, and Hybrid Modeling Approaches
Authors: Lin Yuancheng , Tang Junlong , Guo Jing , Wu Shidong , Li Zheng
Published: February 2025

Artificial intelligence (AI) is increasingly essential for optimizing energy systems, addressing the growing complexity of energy management, and supporting the integration of diverse renewable sources. This study systematically reviews AI-enabled modeling approaches, highlighting their applications, limitations, and potential in advancing sustainable energy systems while offering insights and a framework for addressing real-world energy challenges. Data-driven models excel in energy demand prediction and resource optimization but face criticism for their “black-box” nature, while mechanism-driven models provide deeper system insights but require significant computation and domain expertise. To bridge the gap between these approaches, hybrid models combine the strengths of both, improving prediction accuracy, adaptability, and overall system optimization. This study discusses the policy background, modeling approaches, and key challenges in AI-enabled energy system modeling. Furthermore, this study highlights how AI-enabled techniques are paving the way for future energy system modeling, including integration and optimization for renewable energy systems, real-time optimization and predictive maintenance through digital twins, advanced demand-side management for optimal energy use, and hybrid simulation of energy markets and business behavior.
Electric Vehicles and Energy Communities: Vehicle-to-Grid Opportunities and a Sustainable Future
Authors: Menyhart Jozsef
Published: February 2025

Renewable energy sources and energy independence are becoming increasingly important worldwide, and reducing emissions and optimizing energy use are high on the EU’s agenda. In this context, electric and hybrid vehicles could not only be a means of transport but also an active part of the grid. This paper analyzes one year of empirical data of a hybrid vehicle using a linear programing method that allows the optimization of energy return under different settings. The aim of the study is to determine the contribution that vehicles can make to the stability of the grid and the functioning of energy communities. It also compares the distribution of energy sources used in the EU and presents the current range of V2G-capable vehicle models. The results show that hybrid vehicles can also be effective energy storage devices, especially at fleet level. V2G technology could influence the development of battery production and contribute to the expansion of secondary markets by enabling the recycling of degraded batteries for buildings or renewable energy systems. The article also summarizes the development opportunities and challenges for V2G technology, in particular its role in energy grids and sustainable transport.
Study on the Causes and Countermeasures of High Lightning Trip-Out Rate on Electric Transmission Lines
Authors: Bi Jieting , Wang Jufeng
Published: February 2025

Trip faults are obviously increased by frequent lightning strikes, and increasing lightning trip-out seriously affects a system’s stability and power supply reliability. In this paper, the reasons for high lightning trip-out rates in electric power transmission lines are analyzed in detail from three perspectives, as follows: the substandard lightning resistance level, lightning complexity at a mid-point between towers, and the complexity of first and subsequent lightning stroke conditions. Experiments and simulations demonstrate that the solid-phase gas arc-extinguishing method has a strong ability to extinguish power–frequency continuous-current arcs and to protect against first and subsequent lightning strokes. Since the time taken by gas arc-extinguishing is much less than the response time of relay protection, trip accidents caused by lightning strikes can be avoided and the trip rates of lightning strikes can be reduced using this method. The case analysis and practical operation results show that the solid-phase gas arc-extinguishing lightning protection method can reduce the lightning trip-out rate by more than 90%, completely solve the problem of high lightning trip-out rates, and significantly improve the reliability of power supply.
Peaceful Uses of Nuclear Energy in Less Industrialized Countries: Challenges, Opportunities, and Acceptance
Authors: Raineri Ricardo , Binder Jeffrey , Cohen Adam , Muller Antonio
Published: February 2025

This paper introduces a holistic framework to assist less industrialized countries in adopting nuclear energy (NE) for peaceful purposes considering the challenges and opportunities this entails. It underscores the pressing need for sustainable and secure energy solutions, proposing NE as a viable option. The study aims to delve into the technical, social, economic, regulatory, and policy aspects of NE’s development and its broader applications beyond conventional power generation, such as industrial processes, medical applications, agricultural advancements, and mining activities, explicitly targeting less industrialized regions. Employing a systematic review of existing practices, the paper identifies and examines barriers to NE adoption alongside strategies to mitigate these issues. Findings suggest that NE can play a pivotal role in fostering economic growth and scientific progress, potentially sparking the emergence of new industries within these countries. However, significant obstacles—namely governance, public acceptance, safety, security, development of expertise, and securing financing—pose considerable challenges. The paper concludes that a strategic and well-coordinated deployment of NE is essential for driving socio-economic growth and environmental sustainability in less industrialized countries. It emphasizes the necessity for comprehensive planning and international collaboration to fully unlock NE’s potential, advocating for a multifaceted approach to overcome the identified hurdles.
New Concept of a Ground-Source Refrigeration and Air Conditioning System with Cross-Seasonal Energy Storage Capability
Authors: Delazar Amirreza , Hu Eric , Kotousov Andrei
Published: February 2025

The performance of a conventional Ground-Source Refrigeration and Air Conditioning (GSRAC) system with a borehole heat exchanger (BHE) can be enhanced by addressing the soil thermal imbalance issue that affects these systems. This study proposes a novel concept for seasonal cold energy storage using a Thermal Diode Tank (TDT). The TDT consists of an insulated water tank fitted with an array of heat pipes. By integrating the TDT into a conventional GSRAC system, “cold” energy can be passively collected from ambient air during winter, injected into the BHE, and stored in the soil. The stored “cold” energy can then be retrieved in the summer, facilitating cross-seasonal cold energy storage (CS). Thus, a conventional GSRAC system can be transformed into a GSRAC system with cross-seasonal cold energy storage capability, i.e., GSRAC + CS system. The validated BHE model previously developed by the authors is used to predict the performance improvements achieved using the GSRAC + CS system. The results indicate that the Annual Net Cold Energy Storage Efficiency (ANESE) increased from 5.7% to 10.7% over a ten year period. The average Borehole Performance Improvement (BPI) due to the addition of cold storage capability is 11% over the same timeframe. This study also discusses the impacts of varying design and operational parameters on ANESE and BPI. The results demonstrate that GSRAC + CS systems not only mitigate the soil thermal imbalance issue faced by conventional GSRAC systems, but also require less BHE depth to achieve equivalent performance.
High-Efficiency, Low-Loss, and Wideband 5.8 GHz Energy Harvester Designed Using TSMC 65 nm Process for IoT Self-Powered Nodes
Authors: Rabah Hebah , Albasha Lutfi , Mir Hasan , Quadir Nasir , Abbas Syed Zahid
Published: February 2025

Energy harvesting systems are becoming increasingly vital for sustainable power supply in Internet of Things (IoT) applications. These systems involve capturing and converting energy from environmental sources into electrical power. This paper presents a high-efficiency 5.8 GHz energy harvester for powering such devices, designed in a 65 nm pure CMOS process. The proposed design utilizes a metal-oxide-semiconductor field-effect-transistor-based Dickson charge pump energy harvester for high-frequency energy conversion. Simulation results are presented and discussed on the post-layout verified and extracted circuits with matching implemented to emulate the real-world testing scenarios. The design addresses challenges specific to high-frequency operation, including parasitic capacitances, frequency-dependent leakage currents, and impedance mismatches, ensuring optimal performance at higher frequencies. The evaluation focuses on key metrics such as output voltage and power conversion efficiency (PCE), with the harvester demonstrating an output voltage of 2.88 V and an efficiency of 82.94%.
Frequency Stability Analysis and Control Parameter Optimization in High-Voltage Direct Current-Asynchronous Power Systems with Automatic Generation Control
Authors: Ye Kai , Yang Rongzhao , Li Wei , Mo Weike
Published: February 2025

Asynchronous interconnected systems connected by High-Voltage Direct Current (HVDC) transmission lines struggle with frequency support between interconnected areas, increasing the risk of frequency instability and resulting in low efficiency in frequency resource utilization. This study establishes a frequency dynamic analysis model for asynchronous interconnected power grids and develops an HVDC frequency controller for frequency control in these systems. It analyzes the control effects of HVDC frequency under two scenarios: without Automatic Generation Control (AGC) and with AGC. The research conducts an in-depth study on the system stability and frequency control parameter optimization for HVDC-asynchronous interconnected systems, significantly improving the system’s response speed and accuracy under various conditions through parameter optimization. Furthermore, the introduction of AGC demonstrates good adaptability, and a comparative analysis of HVDC frequency control effects under different AGC control modes is conducted. Finally, case studies validate the effectiveness and robustness of the proposed optimization scheme for frequency stability control in asynchronous interconnected systems under various fault scenarios.
Design and Energy-Saving Analysis of a New LNG Vaporizer Based on Mg-Based Hydrogen Storage Metal
Authors: Yuan Wenke , Yin Zixuan , Su Yan , Liu Zhangyu , Bao Leyi , An Jinyu
Published: February 2025

In order to save the large amount of energy consumption associated with traditional water-bath LNG vaporizer, this paper proposes a novel design for a liquefied natural gas (LNG) vaporizer by comprehensively applying the exothermic property of hydrogen storage metals and the high efficiency of solar energy storage devices. In this paper, the working theory of the proposed LNG vaporizer is first addressed; then, a system featuring a new LNG vaporizer with 1312 mm diameter and 4000 mm length is designed, and its feasibility is demonstrated through technical and economic analysis. After comparison, Mg2Ni has higher economic benefits as a hydrogen storage metal than Mg. When Mg2Ni is used as the hydrogen storage metal, the daily power consumption for vaporizing 1000 m3 of LNG at night during winter is just 89.78 kW·h, with an energy efficiency of about 50%. Combined with solar energy storage devices, for a northern city in China (about 40° N), the savings in electricity costs could be about $2200 per year.
Effect of Dynamic Injection Velocity and Mixed Wettability on Two-Phase Flow Behavior in Porous Media: A Numerical Study
Authors: Hui Wei , Wang Le , Liu Xurui , Wang Yueshe
Published: February 2025

Immiscible displacement in porous media is a crucial microscale flow phenomenon in many fields, necessitating an understanding of the flow mechanisms under dynamic injection velocity and mixing wettability to predict and affect this flow accurately. Initially, a dynamic injection velocity method and a computational domain model considering non-dominant/dominant wetting angles were proposed. Then, microscale flow phenomena were modeled in a pore throat structure and doublet geometry under mixed wetting conditions. Finally, the influence of dynamic injection velocity and mixed wettability on microscale flow were investigated using numerical simulations. The results indicate that when stepwise and piecewise linear changes in injection velocity are observed, unlike continuous injection, two preferential displacement pathways are predominantly formed in the porous media. As the difference between the maximum and minimum injection velocity increases, the recovery efficiency initially decreases and then increases. Recovery efficiency is higher under piecewise linear injection velocity changes. The non-dominant wetting angle determines the distribution and flow of oil-water two-phase systems in porous media. With a dominant controlling wetting angle of 45°, as the non-dominant wetting angle increases, the flow phenomenon changes from one preferential pathway in the back region (30°, 45°) to two preferential pathways (60°, 90°, 120°) and then to one preferential pathway in the middle porous media (150°). As the degree of the non-dominant wetting angle increases, the recovery efficiency first increases and then decreases, with a maximum and minimum difference of 13.6%.
Reinforcement Learning-Based Current Compensation for Brushless Doubly Fed Induction Generators Under Transient- and Low-Voltage Ride-Through Faults
Authors: Marri Muhammad Ismail , Malik Najeeb Ur Rehman , Masud Muhammad , Jumani Touqeer Ahmed , Khidrani Atta Ullah , Shahid Zeeshan
Published: February 2025

Wind and solar energy are increasingly vital for meeting clean renewable energy needs, with Brushless Doubly Fed Induction Generators gaining popularity due to their cost efficiency and reliability. A key challenge in integrating wind energy into the grid is ensuring low-voltage ride-through capability during faults and mitigating voltage fluctuations at the point of common coupling. Existing techniques, such as analytical models and evolutionary algorithms, aim to optimize reactive current compensation but suffer from low accuracy and high response times, respectively. This paper introduces a novel reinforcement learning-based current compensation technique for brushless doubly fed induction generators to address these limitations. The proposed reinforcement learning agent dynamically adjusts the reactive power to minimize voltage dips and stabilize the voltage profile during transient- and low-voltage ride-through faults, leveraging a reward function that penalizes deviations in voltage magnitude and increases in total harmonic distortion beyond 3%. By integrating reinforcement learning with traditional methods, the approach achieves faster and more adaptive compensation. Simulation results show that the reinforcement learning-based technique improves voltage recovery time by up to 50%, reduces total harmonic distortion by up to 44%, and minimizes current overshoot by up to 90% compared to state-of-the-art methods, enhancing the reliability and efficiency of wind energy systems.
The Possibility of Intermittent Water Spray Implementation in a Non-Porous Indirect Evaporative Cooler
Authors: Stefaniak Łukasz , Walaszczyk Juliusz , Karpuk Michał , Rajski Krzysztof , Danielewicz Jan
Published: February 2025

Evaporative cooling is a sustainable and energy-efficient technology based on water evaporation to achieve cooling. It uses air (R-729) and water (R-718) as refrigerants, so its effect on global warming is limited. Recent research focuses development of porous heat exchanger surfaces to be used in evaporative cooling technology with intermittent water spray. However, non-porous surfaces were not investigated. Here, we present the possibility of implementing intermittent water spray in a non-porous indirect evaporative cooler. The experimental results show that it increases the cooling capacity when compared to the constant water spray for chosen outdoor air parameters (20–30 °C and 40–50% relative humidity). Also, the time after the outlet air temperature achieves minimum value (4–6 min) is presented for a certain non-porous heat exchanger. The maximum cooling capacity obtained without spraying is 25–64% higher than the cooling capacity in steady-state conditions under constant water spraying. The regression model approach is employed to describe the observation. The results introduce a new path in evaporative cooling technology development. They also create the possibility of improving the effectiveness of existing systems by modifying only the water system management, without any changes in construction or replacing the heat exchanger.
Ecological Flow Deficit in a Context of Institutional Rigidities and Climate Change: The Case of Mapocho Alto, Central Chile
Authors: Sturla Gino , Figueroa Eugenio
Published: February 2025

Climate change impacts on runoff, coupled with population and production growth, pose significant risks to aquatic ecosystems. These risks are heightened in countries with rigid institutional frameworks that prevent water extraction from adapting to ecological requirements. Central Chile presents a particularly compelling case due to the coexistence of private water rights, challenges in establishing ecological flows, projected reductions in runoff, and the high country’s population share. This study aims to determine current and future ecological flow deficits using two indicators: the accumulated water volume deficit and the frequency of runoff falling below ecological flow thresholds. Given the absence of defined ecological flows in some basins and uncertainties about future water system operations, an original methodology tailored to the Chilean context is proposed. This analysis focuses on the Mapocho Alto system (five basins), which is highly affected by water extraction and outdated ecological flow definitions. Results indicate that annual deficit volumes during the historical period are low across basins and are concentrated between September and November. Under climate change scenarios (three basins), the deficits remain relatively stable in two basins but shift in January–July. However, in the Arrayán en la Montosa basin, climate change significantly increases the deficit volumes and frequencies due to imbalances between the natural water supply and water demand. The conclusions underscore the necessity of addressing institutional constraints, such as static ecological flow definitions, to prevent severe ecosystem issues in basins where runoff is projected to decline while demand remains constant or increases, a concern applicable to other countries with similar institutional frameworks.
Sodium Alginate as a Green Consolidant for Waterlogged Wood—A Preliminary Study
Authors: Villani Elisa , Popescu Carmen-Mihaela , Jancelewicz Mariusz , Stagno Valeria , Capuani Silvia , Broda Magdalena
Published: February 2025

Traditional consolidants commonly used for waterlogged wood conservation often present long-term drawbacks, prompting research into new and reliable alternatives. Reducing reliance on fossil-based chemicals that are harmful to people, the environment, and the climate is a growing trend, and sustainable materials are now being explored as alternative consolidants for conserving waterlogged archaeological wood. Among these bio-based products, sodium alginate, a natural polysaccharide, has shown promising potential. This study aimed to evaluate its effectiveness in stabilising dimensions of severely degraded archaeological elm wood during drying. Various treatments were tested, and dimensional stabilisation (ASE), weight percent gain (WPG), and volumetric shrinkage (Vs) were assessed. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were used to evaluate alginate penetration and interactions with residual wood components. Results indicated that the effectiveness of sodium alginate depends on the treatment method, with the soaking approach and slow drying providing the highest WPG and the best stabilisation without altering the natural wood colour. Although the best achieved anti-shrink efficiency of 40% is insufficient from the conservation perspective, sodium alginate has proven to be a promising consolidant for the conservation of waterlogged wood. Further studies will focus on enhancing its penetration and interactions with residual wood components.
Task-Driven Virtual Machine Optimization Placement Model and Algorithm
Authors: Yang Ran , Li Zhaonan , Qian Junhao , Li Zhihua
Published: February 2025

In cloud data centers, determining how to balance the interests of the user and the cloud service provider is a challenging issue. In this study, a task-loading-oriented virtual machine (VM) optimization placement model and algorithm is proposed integrating consideration of both VM placement and the user’s computing requirements. First, the VM placement is modeled as a multi-objective optimization problem to minimize the makespan of the loading tasks, user rental costs, and energy consumption of cloud data centers; then, an improved chaos-elite NSGA-III (CE-NSGAIII) algorithm is presented by casting the logistic mapping-based population initialization (LMPI) and the elite-guided algorithm in NSGA-III; finally, the presented CE-NSGAIII is employed to solve the aforementioned optimization model, and further, through combination of the above sub-algorithms, a CE-NSGAIII-based VM placement method is developed. The experiment results show that the Pareto solution set obtained using the CE-NSGAIII exhibits better convergence and diversity than those of the compared algorithms and yields an optimized VM placement scheme with shorter makespan, less user rental costs, and lower energy consumption.
Low-Cost Software Evaluation of Communication Delays in Networked Industrial Systems
Authors: Cheminod Manuel , Cibrario Bertolotti Ivan , Valenzano Adriano , Durante Luca
Published: February 2025

Equipment to be installed in real-time industrial control system networks must be carefully characterized before commissioning to ensure it meets performance requirements. However, performance analysis tools may be expensive and come with stringent hardware and software requirements that render them out of reach for many small and medium enterprises. In this paper, we propose a software tool that leverages inexpensive, commonly available personal computer hardware and Linux-based, user-level open source software to enhance portability, flexibility, and ease of use without sacrificing measurement accuracy. An extensive evaluation of the tool’s custom-designed traffic generator shows that it compares favorably with related work. At the same time, the measurement system is able to achieve remarkable accuracy in determining the mean delay and delay variance of the device under test, as also demonstrated by a practical device evaluation example.
Machine Learning for Blockchain and IoT Systems in Smart City
Authors: Lee Cheng-Chi , Do Dinh-Thuan , Imoize Agbotiname Lucky
Published: February 2025

Recent advancements in machine learning algorithms have facilitated the rapid use of blockchain technology and the Internet of Things in the design and development of smart cities [...]
MAGIC: Multi-User Advanced Graphic Immersive Configurator for Sustainable Customization of Complex Design Products—A Sailing Yacht Case Study
Authors: Piccininni Saverio , Dastan Mine , Vangi Fabio , Fiorentino Michele
Published: February 2025

Modern design products are increasingly complex and emotionally significant, demanding versatile and collaborative customization. However, a literature and commercial review reveals a limited availability of flexible, multi-user, photorealistic Virtual Reality (VR) systems for product configuration. We introduce MAGIC (Multi-user Advanced Graphic Immersive Configurator), a collaborative platform combining realistic graphics with ergonomic validation using digital avatars, addressing the limitations of 2D visualization and existing tools. MAGIC is evaluated in a yacht design case study involving 30 participants in an immersive, co-located configuration of a sailing yacht to assess the system’s usability and the potential of VR for customizing complex products. Results show MAGIC’s feasibility in supporting multi-user configuration (100% success rate) and achieving a strong usability score (SUS = 80.83). User feedback highlights that high-quality graphics and additional content significantly enhance immersion and user engagement. However, encountered challenges with navigation methods and spatial perception indicate areas for improvement. MAGIC’s collaborative and immersive capabilities can be extended to other industries demanding proactive customer engagement in the customization of large, heavy products and ergonomic design. Moreover, by promoting prototype dematerialization and providing an interactive remote tool for end users, MAGIC offers potential environmental and economic benefits to boost the competitiveness of small and medium enterprises (SMEs).
Application of Composite Dry Powders for Simultaneous Fire Extinguishment and Liquid Solidification of Methanol
Authors: Ni Xiaomin , Zhang Kai , Zheng Zhong , Wang Wenjie , Hu Shi
Published: February 2025

Extinguishing methanol fires poses significant challenges due to methanol’s high toxicity, polarity, and fluidity. While conventional fire suppressants, such as alcohol-resistant firefighting foam, water mist and dry powders, can extinguish methanol fires, they fail to prevent the spread of liquid methanol, creating a risk of environmental contamination as the mixture of suppressants and methanol flows into surrounding soil and water resources. To address this issue, a novel kind of composite dry powder has been developed to effectively combat methanol pool fires. The powder can not only rapidly extinguish flames but also transform liquid methanol into gel-like substances, significantly reducing the hazards caused by the flow of harmful liquids. Laboratory experiments identify an optimal mass ratio of 0.16 between the composite powder and methanol to achieve complete flame extinction and liquid solidification. The superior performance of as-prepared composite powder could be mainly ascribed to the cooperation of metallic salts, polymers, and silica additives. Additionally, the powder is effective for extinguishing ethanol fires, making it a valuable tool for the emergency management of alcohol fires in leakage incidents.