Search Results (1,223)

The increasing adoption of Plant Factories with Artificial Lighting (PFAL) has intensified the reliance on Internet of Things (IoT) technologies for real-time monitoring and control of environmental and operational variables. While IoT-based architectures enable precise resource management and productivity optimization, PFAL systems remain highly vulnerable to component failures, sensor malfunctions, communication faults, and energy disruptions, which may compromise crop integrity and system reliability. These risks are particularly critical in low-cost and small-scale PFAL implementations, where maintenance capacity and redundancy are often limited. Existing IoT-based PFAL monitoring systems typically address either hardware or software redundancy in isolation and rarely incorporate a dedicated maintenance-oriented fault detection layer validated under realistic multi-failure scenarios. This study addresses these challenges by proposing a low-cost redundant system architecture for PFAL applications that simultaneously integrates (1) hardware redundancy through multi-sensor configurations; (2) analytical redundancy based on residual generation and threshold-based fault isolation; and (3) a maintenance-oriented fault detection layer capable of identifying abnormal internal device conditions. Experimental validation was conducted using four hardware configurations—Arduino Nano with Ethernet, ESP32, STM32 with Wi-Fi, and STM32 with Ethernet—evaluated across five fault scenarios: dust accumulation, water exposure, high temperature, fire detection, and physical impact. The STM32 with Ethernet configuration consistently achieved the fastest fault detection response times across all tested scenarios. Future work will focus on the integration of machine learning-based predictive maintenance algorithms, multi-node PFAL network deployments, and long-term field validation. Full article

This paper presents the design, implementation, and experimental validation of a portable photovoltaic charging station with IoT-based monitoring for autonomous low-power applications. The system integrates a 120 W photovoltaic module, LiFePO₄ battery storage, MPPT regulation, DC/AC conversion, and an ESP32-S3-based acquisition unit connected to a cloud platform for real-time telemetry. Electrical and environmental variables were recorded to evaluate energy balance, conversion losses, State of Charge evolution, and load compatibility under different seasonal operating conditions. Field tests showed that under high-irradiance summer conditions, the prototype supplied multiple laptop loads for approximately 4.5 h with stable operation. In contrast, winter trials revealed a structural energy deficit equivalent to 120% of the initial 24 Ah storage capacity, mainly due to reduced irradiance and cumulative conversion losses ranging from 15% to 25%. Based on the experimental data and deterministic energy-balance modelling, an optimized configuration using a 100 Ah LiFePO₄ battery bank and MPPT regulation was assessed through deterministic energy-balance modelling, thus reducing the required State of Charge to 28.8% under the analyzed operating profile. The results demonstrate the feasibility of a low-cost, IoT-enabled photovoltaic platform for renewable energy harvesting, autonomous power supply, and real-time performance assessment. Full article

The increasing penetration of photovoltaic (PV) systems in agricultural irrigation poses significant challenges in terms of energy self-sufficiency and operational cost, particularly when installed capacity is insufficient to cover pumping demand. This comparative study evaluates the energy and economic performance of three storage-based configurations applied to a real PV-powered irrigation system, using a PV capacity of 112 kWp as a common baseline. The methodology combines hourly energy balance modelling with linear programming optimization, implemented under both a grid energy minimization objective and a net cost minimization objective, within a model predictive control framework. Three scenarios are compared against a passive reference case: battery storage integration (Scenario 1), reservoir-based hydraulic storage (Scenario 2), and a combined electrical and hydraulic storage configuration (Scenario 3). Results show that system performance is strongly conditioned by the chosen objective function. When self-sufficiency is prioritized, Scenario 3 achieves the greatest reduction in grid imports by combining intraday electrical flexibility with demand rescheduling. When net cost minimization is the primary criterion, Scenario 2 proves most competitive, exploiting pumping flexibility and surplus compensation revenues. These findings highlight that storage technology selection in PV irrigation systems should be driven by the primary operational objective rather than by a single performance indicator. Full article

During heavy oil development, the gathering and transportation of low-temperature wellhead-produced fluids are often accompanied by high viscosity, pipe-wall deposition, and high flow resistance, threatening the continuous and stable operation of gathering systems. Existing studies on wellhead heating mainly focus on overall steady-state heating performance, while variable-flow heat transfer and start–stop control in local heating systems remain insufficiently explored. This study aims to evaluate the steady-state heating capacity, transient thermal response, and start–stop control performance of a localized electric heating section under variable-flow conditions. A 3D fluid–solid-coupled heat-transfer model of the heating element, pipe wall, and internal fluid was developed using COMSOL Multiphysics. The steady-state temperature field, transient heating and cooling behavior, and start–stop control characteristics were analyzed under different flow rates. The results show that, at a heating power of 15 kW and a flow rate of 20 m³/d, the maximum outer-wall temperature reached 564 K, and the average outlet fluid temperature reached 308.83 K, indicating effective heating performance. As the flow rate increased from 10 m³/d to 30 m³/d, the maximum pipe-wall temperature and fluid temperature rise both decreased, whereas the average fluid-side heat-transfer coefficient increased from approximately 700 W/(m²·K) to 1800 W/(m²·K), demonstrating enhanced convective heat transfer. Under a dual-threshold control strategy of 463.15–483.15 K, the system maintained the target temperature near 473.15 K under all tested conditions, while the load factor increased from 37.83% to 86.15%. These findings provide theoretical references and engineering support for optimizing power configuration and improving temperature control strategies in local heating systems for wellhead-produced fluids. Full article

This study investigates the energy absorption capacity of large three-honeycomb cell cores of different geometrical configurations, focusing on the influence of the constructive parameters on their impact response. The analyzed sandwich structures were additively manufactured using Onyx (a nylon-based composite) for the core cells and integrated into an assembly consisting of 6060-aluminum face sheets and encapsulated within a 6060-aluminum tube. These configurations represent a realistic engineering solution for lightweight structures designed for energy absorption. The analyses were conducted for two impact energy levels, 20 J and 50 J, enabling the evaluation of the structural sensitivity to different dynamic loading conditions. The results indicate a significant reduction in peak force with an increasing number of cells along the height. Compared to the single-cell configuration, the peak force decreases by approximately 15% for the two-cell configuration and 22.5% for the three-cell configuration, corresponding to a reduction of roughly 9% between the two- and three-cell cases. These findings highlight the critical role of geometry in optimizing the impact performance of honeycomb structures and provide relevant insights for the design of additively manufactured energy-absorbing crush-type components in engineering applications. Full article

This study investigates the quasi-static mechanical behavior of a flexible anti-collision ring (FACR) for bridge protection through axial tests and finite element (FE) simulations. The FACR features a multi-layer steel wire rope coil (SWRC) encased in a chloroprene rubber matrix. Quasi-static tensile and compressive tests (80 mm/s) were conducted on both the SWRC and the FACR, with full-field strain distributions captured via digital image correlation (DIC). The results demonstrate that the rubber matrix significantly enhances load-bearing capacity (by 200% in compression and 337% in tension) and energy dissipation (by 403% and 620%, respectively), with bending identified as the dominant deformation mode. An FE model was developed and validated against experimental data, then employed for parametric analysis. The cross-sectional ratio, governed by the number of SWRC layers, exhibits a strong nonlinear influence on the tensile response, and a three-layer configuration is identified as optimal, achieving the highest energy absorption without compromising compressive performance. A layer-dependent mechanism analysis reveals that excessive layers lead to a drastic stiffness reduction in outer coils, impeding coordinated load sharing. Building upon this mechanism, an optimized two-layer arrangement maximizing the inner-layer SWRC proportion is proposed, achieving 2.0× and 1.9× improvements in peak tensile force and energy dissipation, respectively, while using fewer steel wires. This work provides a fundamental understanding and an efficient optimization strategy for FACRs. Full article

Smoke spread from concourse fires into long entrance passageways can threaten evacuation in deep-buried subway stations, especially when smoke moves upward along inclined escalator sections. This study used a 1:8-scale Fire Dynamics Simulator model to investigate smoke control in a concourse connected to two long entrance passageways. Concourse-only smoke exhaust, conventional combined smoke exhaust, different passageway vent configurations, and an optimized near-source concentrated arrangement were compared. The baseline concourse extraction rate failed to prevent smoke from entering the passageways. At a heat release rate of 15.55 kW, smoke was nearly prevented from entering landing I only when the concourse extraction rate was increased to six times the baseline value. Under conventional combined exhaust, the passageway extraction capacity was distributed between landing I and landing II, but smoke still entered escalator section I. When the total extraction rate of each single-side passageway was unchanged, concentrating the extraction capacity at landing I allowed smoke to be extracted before entering escalator section I. The optimized arrangement prevented smoke from entering escalator section I under both centered and right-offset fire source conditions for the tested passageway geometry, heat release rate, and extraction-rate conditions. Full article

This study presents a novel iterative dual-loop methodology for the technical sizing of DC-coupled PV-BESS systems. The method was implemented for a commercial broiler farm characterized by a highly variable electricity demand profile (annual consumption: 7.6 MWh; coefficient of variation: 53%). The methodology introduces two original energy utilization indicators—the photovoltaic-to-converter matching factor (W_{PV_S}) and the photovoltaic-to-BESS matching factor (W_{PV_B})—enabling purely technical optimization independent of economic conditions. Minimization of the radius of curvature of the WPVB characteristic curve is applied as a rigorous mathematical criterion for determining the optimal BESS capacity. Simulation results indicate that the optimal configuration consists of a 9.7 kWp photovoltaic system, a 7 kW DC converter, and a 15 kWh battery storage system. The integration of an optimally sized energy storage system increased the self-consumption coverage ratio from 38% to 59% and improved the photovoltaic energy utilization factor from 35% to 54%. Additional economic analysis demonstrates that the PV-only subsystem achieves a simple payback period ranging from 8 to 18 years, depending on the selected pricing scenario. Consequently, the technically optimal configuration identified using the proposed methodology represents a practically feasible investment for broiler production facilities operating under Polish net-billing conditions. The proposed methodology provides a reproducible, economically independent framework for the design of DC-coupled PV-BESS systems in agricultural prosumer facilities, addressing a critical gap in the optimization literature and offering practical sizing guidelines applicable to similarly high-variability load profiles. Full article

Hybrid power generation systems are an effective solution for matching energy production with electrical load demand. In this study, we examine the viability of a grid-connected hybrid PV/Wind system for meeting the electricity demand of the Lafarge cement factory in Al-Tafilah, Jordan, using HOMER Pro software. The results indicate that the optimal configuration consists of a $6.1 \mathrm{M}\mathrm{W}$ wind turbine and a $22.8 \mathrm{M}\mathrm{W}$ PV array, producing $71.94 \mathrm{G}\mathrm{W}\mathrm{h}$ annually, with wind and PV contributing $31.3\%$ and $68.7\%,$ respectively. The system achieves a 100% renewable fraction while maintaining a high level of reliability, with unmet load and capacity shortage limited to $0.057\%$ and $0.1\%,$ respectively. The economic evaluation reveals a levelized cost of energy (LCOE) of $0.13 \mathrm{U}\mathrm{S}\mathrm{D}/\mathrm{k}\mathrm{W}\mathrm{h}$ and a net present cost (NPC) of $\mathrm{U}\mathrm{S}\mathrm{D} 25.827 \mathrm{m}\mathrm{i}\mathrm{l}\mathrm{l}\mathrm{i}\mathrm{o}\mathrm{n}$, representing a $27.8\%$ reduction in LCOE compared to the national grid tariff. In this study, we present a novel large-scale PV/Wind system for the cement industry in Jordan, based on real data, with enhanced techno-economic performance. The innovation of this research lies in the development and optimization of a large-scale grid-connected hybrid PV/Wind system for the cement industry in Jordan, utilizing actual industrial load data and site-specific renewable energy resources. Unlike previous PV-dominated studies, the proposed system integrates a significant contribution of wind energy to improve system reliability and renewable energy penetration, reduce dependency on the national grid, and improve the overall techno-economic performance under actual industrial operating conditions. Full article

One of the remaining challenges in deploying 3D CNN models in resource-constrained environments is the high computational demand. In this paper, we design three lightweight architectures that have distinct spatiotemporal topologies, namely, Lite-R21D, Lite-MC3, and Lite-LF, to reduce computational cost. However, these compact models have restricted representational capacity, which consequently limits their ability to capture complex spatiotemporal features. To overcome this, we employ Knowledge Distillation (KD) and further investigate hybrid combinations of response-based, spatiotemporal attention, and intermediate feature alignment paradigms. By analyzing knowledge transfer across these diverse architectures, our experiments on UCF101 and HMDB51 demonstrate that combining these distillation configurations consistently outperforms single KD methods, resulting in a substantial increase in accuracy across all Student models. Our optimal hybrid setup achieves 92.07% accuracy on UCF101 and 65.56% on HMDB51, compared to the Teacher’s 94.74% and 69.48%, reducing the accuracy gap to only 2.67% and 3.92%. These gains are achieved alongside significant efficiency improvements. The proposed models operate with up to 87% fewer parameters and an 89% reduction in Floating-Point Operations (FLOPs), achieving 6.7× faster inference. Our findings highlight that hybrid distillation is an effective approach for transferring and utilizing complex spatiotemporal knowledge in lightweight models. Full article

This study presents a comprehensive Life Cycle Assessment (LCA) of a perovskite/silicon (PVSK/Si) tandem photovoltaic technology. The study evaluates the environmental impact considering an application in a hypothetical PV plant. This analysis uses laboratory-scale data projected onto industrial-scale conditions, with a focus on a theoretical utility-scale photovoltaic plant located in Italy. Three electrode configurations, Au, Au/ITO, and MoOx/ITO, are assessed to identify environmental hotspots and optimize material and energy use. Among these options, MoOx/ITO produces lower environmental impacts, especially in terms of climate change (4.54 g CO₂-eq/cm² compared with 5.54 g CO₂-eq/cm² generated by Au electrode cell) and resource consumption (PVSK cell with MoOx/ITO electrode: 3.23 × 10^−f5 g Sb-eq/cm², and PVSK cell with Au electrode: 5.24 × 10⁻⁵ g Sb-eq/cm²), due to the absence of gold use. The study finally compares environmental impacts of a photovoltaic system employing tandem-cell modules with those of a system based on heterojunction (HJT) modules, highlighting the advantages of higher efficiency and reduced land consumption at equal installed capacity, leading to a 25% reduction in impacts in the land-use category. These findings support the strategic development of tandem modules for future large-scale deployment in the photovoltaic energy sector. Full article

The growing demand for energy-efficient urban rail transit has led to the increasing deployment of reversible substations (RS) in traction power supply systems. These substations, equipped with bidirectional converter devices (BCDs), involve high initial costs and complex parameter optimization challenges. This paper presents a coordinated optimization method for BCD-equipped RS using a two-layer model. In the upper layer, the model determines the siting of RS and the capacity of BCD to minimize life-cycle cost (LCC). In the lower layer, it adjusts the control parameters of BCDs to reduce annual operating cost. An improved salp swarm algorithm (ISSA), incorporating Tent chaotic mapping and Levy flight, is developed to solve the model. A case study based on an 18.2 km subway line shows that the optimized configuration reduces overall cost by 5.12% and electricity cost by 10.53% compared with a conventional rectifier system. Moreover, it achieves a 1.19% reduction in electricity cost over a system with fixed control parameters, while maintaining rail potential and catenary voltage within safe limits. These findings demonstrate that the proposed method strikes an effective balance between initial investment and long-term operational benefits, contributing to improved energy efficiency and economic performance. Full article

Radio-over-Fiber (RoF) integrated with Free-Space Optical (FSO) communication as a fronthaul is a promising solution for next-generation wireless systems, but severely suffers from the frequency-selective characteristics of hybrid RoF-FSO channels. This paper presents a measurement-driven, deployment-oriented optimization that jointly performs structure-aware pilot placement and sixth-order polynomial regression channel interpolation to enhance spectral efficiency and signal quality in quasi-static indoor FSO environments. Differential channel analysis across three transmission scenarios—Electrical Back-to-Back (B2B), Fiber B2B, and FSO—identifies critical subcarriers with high frequency-selective variation that require dense pilot allocation. A gradient-based algorithm positions 50 pilots with dense spacing (every 3 subcarriers) in critical regions and sparse spacing (every 9 subcarriers) in stable regions, reducing pilot overhead by 26.5% and increasing data capacity by 5.3% (340 → 358 subcarriers) compared to uniform placement of 68 pilots. Sixth-order polynomial regression models the non-linear channel frequency response, overcoming limitations of conventional linear interpolation. Experimental validation on a 4-QAM RoF-OFDM system over 40.6 MHz bandwidth shows that structure-aware pilot placement alone reduces Error Vector Magnitude (EVM) by 15.9%, while polynomial regression alone improves it by 15.7%. Combined optimization of structure-aware pilot placement with polynomial regression interpolation achieves 23.5% EVM reduction and 460× lower BER, equivalent to 3.2 dB SNR gain at BER = ${10}^{-6}$. Comparative analysis of four system configurations confirms consistent performance advantages across SNRs of 12–30 dB. The proposed measure-once, optimize-forever paradigm requires only one-time channel characterization, making it suitable for short-range controlled quasi-static indoor FSO links in 5G/6G fronthaul, optical wireless networks, and inter-building backhaul applications. Full article

Addressing the challenge of power supply stability caused by the intermittent nature of photovoltaic power generation in off-grid microgrids, this study uses a commercial park in Wuhan as a case study and optimizes the capacity configuration of a photovoltaic–storage–hydrogen fuel cell hybrid microgrid system based on HOMER Pro software. First, a topology of the off-grid microgrid is constructed, comprising photovoltaic (PV), lithium-ion batteries, hydrogen fuel cells, and a diesel generator as backup. The power output characteristics, efficiency curves, and life-cycle cost models of each component are accurately established. On this basis, two typical operation strategies, namely Load Following (LF) and Cycle Charging (CC), are proposed and compared. The influence of different strategies on the optimal capacity configuration and operational economics is systematically analyzed, and the Cycle Charging strategy is identified as the optimal operation strategy for this scenario. Subsequently, a multi-scenario capacity optimization design is further conducted based on the optimal operation strategy. The minimization of net present cost (NPC) is taken as the primary objective, while multiple evaluation indicators such as renewable fraction (RF), levelized cost of electricity (LCOE), energy storage cycle life degradation, and system redundancy rate are comprehensively considered. The results show that, while ensuring 100% power supply reliability, the proposed model reduces the net present cost (NPC) by approximately 14.4% compared with the conventional PV-storage scheme. The renewable fraction (RF) reaches 95.8%, while the reliance on lithium-ion battery capacity is significantly reduced (battery capacity configuration decreased by 24.3%). This effectively extends the energy storage lifespan and enhances the overall economic and environmental benefits. The results provide a theoretical basis and technical reference for the planning and design of off-grid microgrids with high penetration of renewable energy. Full article

The intermittent nature of renewable energy systems and the mismatch between power generation and load demand necessitate the integration of efficient energy storage systems (ESSs). Among large-scale energy storage technologies, pumped hydro-energy storage systems (PHESs) are widely recognized as one of the most cost-effective and longest-lifetime storage solutions under favorable geographical conditions. This study proposes and optimizes a hybrid renewable energy system (HRES) for the Wadi Baish region in Saudi Arabia as a real case study, where the significant elevation difference between the nearby mountains and the existing lake provides favorable conditions for PHES implementation. A nested optimization framework is developed to determine the optimal sizing and operation of the HRES components. The external optimization loop employs the non-dominated sorting genetic algorithm II (NSGA-II) to optimize system sizing, while the internal optimization loop uses mixed-integer linear programming (MILP) to optimally dispatch the PHES, battery energy storage system (BESS), and hydrogen energy storage system (HESS). In addition, demand-side management (DSM) is coordinated with the MILP dispatch strategy to improve system performance and reliability. The results show that the optimized system can supply a 10 MW average load with a renewable energy penetration of 98.7%. The proposed configuration achieves a total lifecycle cost of USD 231.37 million and avoids approximately 898.58 kt of CO₂ emissions over the project lifetime. PHES operates as the primary bulk energy storage technology due to its high storage capacity and low degradation characteristics. Furthermore, the degradation-aware model predicts battery replacement every 12 years and HESS replacement every 5 years. Compared with rule-based control, the MILP-based dispatch strategy reduces grid dependency by 87%. The coordinated DSM and MILP operation also reduces the levelized cost of energy to USD 0.066/kWh while improving overall system reliability. These findings demonstrate the importance of coordinated energy management and accurate degradation modeling in the optimal design and operation of renewable-based HRES configurations. Full article