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Search Results (191)

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Keywords = energy proportionality

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30 pages, 7246 KiB  
Article
Linear Dependence of Sublimation Enthalpy on Young’s Elastic Modulus: Implications for Thermodynamics of Solids
by Anne M. Hofmeister
Materials 2025, 18(15), 3535; https://doi.org/10.3390/ma18153535 - 28 Jul 2025
Viewed by 347
Abstract
Classical thermodynamics omits rigidity, which property distinguishes solids from gases and liquids. By accounting for rigidity (i.e., Young’s elastic modulus, ϒ), we recently amended historical formulae and moreover linked heat capacity, thermal expansivity, and ϒ. Further exploration is motivation by the importance of [...] Read more.
Classical thermodynamics omits rigidity, which property distinguishes solids from gases and liquids. By accounting for rigidity (i.e., Young’s elastic modulus, ϒ), we recently amended historical formulae and moreover linked heat capacity, thermal expansivity, and ϒ. Further exploration is motivation by the importance of classical thermodynamics to various applied sciences. Based on heat performing work, we show here, theoretically, that density times sublimation enthalpy divided by the molar mass (ρΔHsub/M, energy per volume), depends linearly on ϒ (1 GPa = 109 J m−3). Data on diverse metals, non-metallic elements, chalcogenides, simple oxides, alkali halides, and fluorides with cubic structures validate this relationship at ambient conditions. Furthermore, data on hcp metals and molecular solids show that ρΔHsub/M is proportional to ϒ for anisotropic materials. Proportionality constants vary only from 0.1 to 0.7 among these different material types (>100 substances), which shows that the elastic energy reservoir of solids is large. Proportionality constants depend on whether molecules or atoms are sublimated and are somewhat affected by structure. We show that ductility of refractory, high-ϒ metals affect high-temperature determinations of their ΔHsub. Our results provide information on sublimation processes and subsequent gas phase reactions, while showing that elasticity of solids is the key parameter needed to assessing their energetics. Implications are highlighted. Full article
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18 pages, 2761 KiB  
Article
Dual-Functioned Magnesium-Enriched Biochar Hydrogels for Phosphate Recovery and Slow-Release Nutrient Delivery
by Nur Maisarah Mohamad Sarbani, Hiroyuki Harada, Mitsuru Aoyagi and Endar Hidayat
Water 2025, 17(15), 2235; https://doi.org/10.3390/w17152235 - 27 Jul 2025
Viewed by 256
Abstract
Excessive phosphate from agriculture and industry has led to widespread eutrophication, posing a serious environmental threat. To address this issue, metal-modified biochars have emerged as promising adsorbents due to their high affinity for phosphate ions. This study investigates the application of two magnesium-modified [...] Read more.
Excessive phosphate from agriculture and industry has led to widespread eutrophication, posing a serious environmental threat. To address this issue, metal-modified biochars have emerged as promising adsorbents due to their high affinity for phosphate ions. This study investigates the application of two magnesium-modified biochar hydrogels denoted as magnesium–bamboo biochar hydrogel (Mg-BBH) and magnesium–pulp biochar hydrogel (Mg-PBH) for phosphate recovery from aqueous solutions, with an additional aim as slow-release fertilizers. The adsorbents were synthesized by impregnating Mg-modified biochars into sodium-alginate-based hydrogel. The influence of initial phosphate concentration, contact time, and temperature were investigated to determine optimal adsorption conditions. Both adsorbents exhibited excellent adsorption performance, with maximum capacities of 309.96 mg PO4/g (Mg-BBH) and 234.69 mg PO4/g (Mg-PBH). Moreover, the adsorption performance of the adsorbents was greatly influenced by the magnesium content. The adsorption process followed the Temkin isotherm and pseudo-second-order kinetics, suggesting that the adsorption energy decreases proportionally with surface coverage and the phosphate uptake was governed by chemisorption. Thermodynamic study confirmed the process was spontaneous and endothermic at 40 °C. A slow-release study further demonstrated a great release of phosphate in soil over time. These findings highlight the dual functionality of Mg-BBH and Mg-PBH as effective materials for both phosphate recovery and controlled nutrient delivery, contributing to sustainable phosphate management. Full article
(This article belongs to the Section Soil and Water)
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13 pages, 1895 KiB  
Article
Class-Dependent Solar Flare Effects on Mars’ Upper Atmosphere: MAVEN NGIMS Observations of X8.2 and M6.0 from September 2017
by Junaid Haleem and Shican Qiu
Universe 2025, 11(8), 245; https://doi.org/10.3390/universe11080245 - 25 Jul 2025
Viewed by 226
Abstract
Transient increments of X-ray radiation and extreme ultraviolet (EUV) during solar flares are strong drivers of thermospheric dynamics on Mars, yet their class-dependent impacts remain poorly measured. This work provides the first direct, side-by-side study of Martian thermospheric reactions to flares X8.2 on [...] Read more.
Transient increments of X-ray radiation and extreme ultraviolet (EUV) during solar flares are strong drivers of thermospheric dynamics on Mars, yet their class-dependent impacts remain poorly measured. This work provides the first direct, side-by-side study of Martian thermospheric reactions to flares X8.2 on 10 September 2017 and M6.0 on 17 September 2017. This study shows nonlinear, class-dependent effects, compositional changes, and recovery processes not recorded in previous investigations. Species-specific responses deviated significantly from irradiance proportionality, even though the soft X-ray flux in the X8.2 flare was 13 times greater. Argon (Ar) concentrations rose 3.28× (compared to 1.13× for M6.0), and radiative cooling led CO2 heating to approach a halt at ΔT = +40 K (X8.2) against +19 K (M6.0) at exobase altitudes (196–259 km). N2 showed the largest class difference, where temperatures rose by +126 K (X8.2) instead of +19 K (M6.0), therefore displaying flare-magnitude dependent thermal sensitivity. The 1.95× increase in O concentrations during X8.2 and the subsequent decrease following M6.0 (−39 K cooling) illustrate the contradiction between photochemical production and radiative loss. The O/CO2 ratio at 225 km dropped 46% during X8.2, revealing compositional gradients boosted by flares. Recovery timeframes varied by class; CO2 quickly re-equilibrated because of effective cooling, whereas inert species (Ar, N2) stabilized within 1–2 orbits after M6.0 but needed >10 orbits of the MAVEN satellite after the X8.2 flare. The observations of the X8.2 flare came from the western limb of the Sun, but the M6.0 flare happened on the far side. The CME shock was the primary driver of Mars’ EUV reaction. These findings provide additional information on atmospheric loss and planetary habitability by indicating that Mars’ thermosphere has a saturation threshold where strong flares induce nonlinear energy partitioning that encourages the departure of lighter species. Full article
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16 pages, 1027 KiB  
Article
Climate Change Mitigation vs. Renewable Energy Consumption and Biomass Demand
by Renata Dagiliūtė and Vaiva Kazanavičiūtė
Land 2025, 14(7), 1320; https://doi.org/10.3390/land14071320 - 21 Jun 2025
Viewed by 432
Abstract
The land use, land-use change, and forestry (LULUCF) sector plays a crucial role in climate change mitigation; therefore, it is included in national and international climate change policies. However, renewable energy and bioeconomy development increase the demand for biomass for energy and material [...] Read more.
The land use, land-use change, and forestry (LULUCF) sector plays a crucial role in climate change mitigation; therefore, it is included in national and international climate change policies. However, renewable energy and bioeconomy development increase the demand for biomass for energy and material needs and challenge greenhouse gas (GHG) removal in LULUCF. Therefore, this study aims to analyze whether climate change mitigation and bioeconomy goals are compatible from an LULUCF perspective at the EU level. This study mainly covers the 2000–2020 period, looking at decoupling trends and LULUCF removal as well as estimating the substitution effect, which enables a broader view of the LULUCF GHG removal potential. The results reveal that decoupling is taking place at the EU level regarding economic growth and GHG, with a steady increase in renewables. The share of biomass in renewables is increasing at a slower pace, and the reduction in LULUCF GHG removal is proportionally lower compared to the pace of wood being harvested from forest land at the EU level. Still, biomass demand raises the pressure for LULUCF GHG removal, considering the sector itself is highly uncertain. Despite this, some possibilities to align climate and bioeconomy goals could remain, especially if the substitution effect is considered. Based on historical data, the estimated substitution effect is even higher (−367 mill. t CO2 eq. on average in 2000–2020) than the sector’s removal (−300 mill. t CO2 eq. on average in 2000–2020) and is dominated by material substitution (61%). Hence, LULUCF contributes to a reduction in GHG in other sectors, but it is still seldom acknowledged and not accounted for. Full article
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28 pages, 9823 KiB  
Article
Local Entropy Optimization–Adaptive Demodulation Reassignment Transform for Advanced Analysis of Non-Stationary Mechanical Signals
by Yuli Niu, Zhongchao Liang, Hengshan Wu, Jianxin Tan, Tianyang Wang and Fulei Chu
Entropy 2025, 27(7), 660; https://doi.org/10.3390/e27070660 - 20 Jun 2025
Viewed by 228
Abstract
This research proposes a new method for time–frequency analysis, termed the Local Entropy Optimization–Adaptive Demodulation Reassignment Transform (LEOADRT), which is specifically designed to efficiently analyze complex, non-stationary mechanical vibration signals that exhibit multiple instantaneous frequencies or where the instantaneous frequency ridges are in [...] Read more.
This research proposes a new method for time–frequency analysis, termed the Local Entropy Optimization–Adaptive Demodulation Reassignment Transform (LEOADRT), which is specifically designed to efficiently analyze complex, non-stationary mechanical vibration signals that exhibit multiple instantaneous frequencies or where the instantaneous frequency ridges are in close proximity to each other. The method introduces a demodulation term to account for the signal’s dynamic behavior over time, converting each component into a stationary signal. Based on the local optimal theory of Rényi entropy, the demodulation parameters are precisely determined to optimize the time–frequency analysis. Then, the energy redistribution of the ridges already generated in the time–frequency map is performed using the maximum local energy criterion, significantly improving time–frequency resolution. Experimental results demonstrate that the performance of the LEOADRT algorithm is superior to existing methods such as SBCT, EMCT, VSLCT, and GLCT, especially in processing complex non-stationary signals with non-proportionality and closely spaced frequency intervals. This method provides strong support for mechanical fault diagnosis, condition monitoring, and predictive maintenance, making it particularly suitable for real-time analysis of multi-component and cross-frequency signals. Full article
(This article belongs to the Section Multidisciplinary Applications)
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12 pages, 2393 KiB  
Article
Influence of PVP and PEG on the Electrochemical Synthesis of Magnesium Hydroxide
by Shengqing Wang, Fangyang Liu, Zongliang Zhang, Jun Wang and Liangxing Jiang
Materials 2025, 18(12), 2917; https://doi.org/10.3390/ma18122917 - 19 Jun 2025
Viewed by 280
Abstract
The functional performance of magnesium hydroxide (Mg(OH)2) is intrinsically governed by its crystallographic morphology. Herein, we demonstrate an electrochemical deposition strategy to synthesize Mg(OH)2 from abandoned MgCl2 resources in salt lakes, achieving simultaneous waste valorization and morphology control. Systematic [...] Read more.
The functional performance of magnesium hydroxide (Mg(OH)2) is intrinsically governed by its crystallographic morphology. Herein, we demonstrate an electrochemical deposition strategy to synthesize Mg(OH)2 from abandoned MgCl2 resources in salt lakes, achieving simultaneous waste valorization and morphology control. Systematic investigations were conducted on the effects of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) as surfactants on electrochemical parameters (cell voltage, pH, current efficiency, and energy consumption) and morphological evolution (XRD, SEM, and laser particle size analysis). Results show that the cell voltage and pH increased proportionally with surfactant concentration, with a current efficiency of 93.86% and an optimal energy consumption of 4.15 kW h·t−1 at an optimal PVP concentration of 6 g·L−1. PEG addition exhibited a similar trend in process parameter modulation. Morphological evolution analysis revealed that appropriate PEG dosage promoted the transformation of irregular Mg(OH)2 flakes into near-spherical platelets, accompanied by a measurable increase in particle size. This work establishes structure–property relationships between surfactant molecular design and Mg(OH)2 crystallization, providing theoretical support for the controllable electrochemical preparation of magnesium hydroxide with different morphologies. Furthermore, it opens up a novel and innovative technical pathway to promote the high-value utilization of abandoned magnesium resources in salt lakes. Full article
(This article belongs to the Section Advanced Materials Characterization)
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14 pages, 1816 KiB  
Article
On Optimally Selecting Candidate Detectors with High Predicted Radio Signals from Energetic Cosmic Ray-Induced Extensive Air Showers
by Tudor Alexandru Calafeteanu, Paula Gina Isar and Emil Ioan Slușanschi
Universe 2025, 11(6), 192; https://doi.org/10.3390/universe11060192 - 18 Jun 2025
Viewed by 243
Abstract
Monte Carlo simulations of induced extensive air showers (EASs) by ultra-high-energy cosmic rays are widely used in comparison with measured events at experiments to estimate the main cosmic ray characteristics, such as mass, energy, and arrival direction. However, these simulations are computationally expensive, [...] Read more.
Monte Carlo simulations of induced extensive air showers (EASs) by ultra-high-energy cosmic rays are widely used in comparison with measured events at experiments to estimate the main cosmic ray characteristics, such as mass, energy, and arrival direction. However, these simulations are computationally expensive, with running time scaling proportionally with the number of radio antennas included. The AugerPrime upgrade of the Pierre Auger Observatory will feature an array of 1660 radio antennas. As a result, simulating a single EAS using the full detector array will take weeks on a single CPU thread. To reduce the simulation time, detectors are commonly pre-selected based on their proximity to the shower core, using a selection ellipse based on the Cherenkov radiation footprint scaled by a fixed constant factor. While effective, this approach often includes many noisy antennas at high zenith angles, reducing computational efficiency. In this paper, we introduce an optimal method for selecting candidate detectors with high predicted signal-to-noise ratio for proton and iron primary cosmic rays, replacing the constant scaling factor with a function of the zenith angle. This approach significantly reduces simulation time—by more than 50% per CPU thread for the heaviest, most inclined showers—without compromising signal quality. Full article
(This article belongs to the Special Issue Ultra-High-Energy Cosmic Rays)
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24 pages, 3719 KiB  
Article
Evaluating Self-Produced PLA Filament for Sustainable 3D Printing: Mechanical Properties and Energy Consumption Compared to Commercial Alternatives
by Luca Fontana, Paolo Minetola, Mankirat Singh Khandpur and Alberto Giubilini
J. Manuf. Mater. Process. 2025, 9(6), 172; https://doi.org/10.3390/jmmp9060172 - 24 May 2025
Viewed by 1182
Abstract
This study investigates the feasibility of self-producing polylactic acid (PLA) filament for use in 3D printing. The filament was fabricated using a desktop single-screw extruder and evaluated against commercially available PLA in terms of mechanical properties and energy consumption. Specimens were printed at [...] Read more.
This study investigates the feasibility of self-producing polylactic acid (PLA) filament for use in 3D printing. The filament was fabricated using a desktop single-screw extruder and evaluated against commercially available PLA in terms of mechanical properties and energy consumption. Specimens were printed at two layer heights (0.2 mm and 0.3 mm) and four infill densities (25%, 50%, 75%, and 100%). The self-produced filament exhibited lower diameter precision (1.67 ± 0.21 mm), which resulted in mass variability up to three orders of magnitude higher than that of the commercial filament. Thermal analysis confirmed that the extrusion and printing process did not significantly alter the thermal properties of PLA. Mechanical testing revealed that a layer height 0.3 mm consistently yielded higher stiffness and tensile strength in all samples. When normalized by mass, the specimens printed with commercial filament demonstrated approximately double the ultimate tensile strength compared to those that used self-produced filament. The energy consumption analysis indicated that a 0.3 mm layer height improved printing efficiency, cutting specific energy consumption by approximately 50% and increasing the material deposition rate proportionally. However, the total energy required to print with self-produced filament was nearly three times higher than that for commercial filament, primarily due to material waste that stems from inconsistencies in the diameter of the filament. These findings are significant in evaluating the practicality of self-produced PLA filament, particularly in terms of mechanical performance and energy efficiency. Full article
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23 pages, 4102 KiB  
Article
Analysis and Validation of the Signal-to-Noise Ratio for an Atmospheric Humidity Profiling Spectrometer Based on 1D-Imaging Spatial Heterodyne Spectroscopy
by Shaochun Xie, Haiyan Luo, Zhiwei Li, Wei Jin, Qiong Wu, Mai Hu, Yang Hong and Wei Xiong
Remote Sens. 2025, 17(11), 1810; https://doi.org/10.3390/rs17111810 - 22 May 2025
Viewed by 463
Abstract
Sub-kilometer spatial resolution humidity profiles from the stratosphere to the mesosphere are essential for investigating the function of atmospheric water vapor in the global water and energy cycles as well as in radiation transport. The significant variations in atmospheric radiation at low altitudes [...] Read more.
Sub-kilometer spatial resolution humidity profiles from the stratosphere to the mesosphere are essential for investigating the function of atmospheric water vapor in the global water and energy cycles as well as in radiation transport. The significant variations in atmospheric radiation at low altitudes and the gradual changes at high altitudes pose challenges to the data acquisition and processing methods of limb imaging spectrometers that rely on atmospheric scattering and absorption mechanisms. In this paper, the effects of two binning techniques—interferogram binning and recovered spectrum binning—on improving the spectral signal-to-noise ratio (SNR) are examined through theoretical analysis and simulations, exemplified by a one-dimensional (1D) imaging spatial heterodyne spectrometer designed for measuring atmospheric humidity profiles. Rician random variables are employed to characterize the amplitude of the recovered spectral points under varying signal conditions, from which spectral SNR expressions are derived for both binning methods. The difference in both methods is evaluated through numerical simulations and experiments. Simulation results demonstrate that, with an integration time of 0.3 s and a spectral resolution of 0.03 nm, the input signal below 50 km is strong, with photon noise being the dominant factor, and both binning methods improve SNR proportionally to the square root of the number of binned rows. As the signal weakens above 50 km, additive noise gradually becomes dominant with increasing tangent altitude, and spectrum binning yields a higher SNR than interferogram binning. Experimental data obtained from a similar type of spectrometer further validate these simulation findings. The results indicate that spectrum binning provides greater advantages in improving the SNR for detecting water vapor in the mesosphere, paving the way for achieving a higher vertical resolution in subsequent retrievals. Full article
(This article belongs to the Special Issue Optical Remote Sensing Payloads, from Design to Flight Test)
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23 pages, 6826 KiB  
Article
Digestate Application on Grassland: Effects of Application Method and Rate on GHG Emissions and Forage Performance
by Petr Šařec, Václav Novák, Oldřich Látal, Martin Dědina and Jaroslav Korba
Agronomy 2025, 15(5), 1243; https://doi.org/10.3390/agronomy15051243 - 20 May 2025
Viewed by 563
Abstract
The application of digestate as a fertilizer offers a promising alternative to synthetic inputs on permanent grasslands, with benefits for productivity and environmental performance. This four-year study evaluated the impact of two digestate application methods—disc injection (I) and band spreading (S)—combined with four [...] Read more.
The application of digestate as a fertilizer offers a promising alternative to synthetic inputs on permanent grasslands, with benefits for productivity and environmental performance. This four-year study evaluated the impact of two digestate application methods—disc injection (I) and band spreading (S)—combined with four dose variants (0, 20, 40, and 80 m3·ha−1), including split-dose strategies. Emissions of ammonia (NH3), carbon dioxide (CO2), and methane (CH4) were measured using wind tunnel systems immediately after application. Vegetation status was assessed via Sentinel-2-derived Normalized Difference Vegetation Index, Normalized Difference Water Index, and Modified Soil Adjusted Vegetation Index, and agronomic performance through dry matter yield (DMY), net energy for lactation (NEL), and relative feed value (RFV). NH3 and CO2 emissions increased proportionally with digestate dose, while CH4 responses suggested a threshold effect, but considering solely the disc injection, CH4 flux did not increase markedly with higher application rates. Disc injection resulted in significantly lower emissions of the monitored fluxes than band spreading. The split-dose I_40+40 variant achieved the highest DMY (3.57 t·ha−1) and improved forage quality, as indicated by higher NEL values. The control variant (C, no fertilization) had the lowest yield and NEL. These results confirm that subsurface digestate incorporation in split doses can reduce emissions while supporting yield and forage quality. Based on the findings, disc injection at 40+40 m3·ha−1 is recommended as an effective option for reducing emissions and maintaining productivity in managed grasslands. Full article
(This article belongs to the Section Grassland and Pasture Science)
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24 pages, 5634 KiB  
Article
An MINLP Optimization Method to Solve the RES-Hybrid System Economic Dispatch of an Electric Vehicle Charging Station
by Olukorede Tijani Adenuga and Senthil Krishnamurthy
World Electr. Veh. J. 2025, 16(5), 266; https://doi.org/10.3390/wevj16050266 - 13 May 2025
Cited by 1 | Viewed by 535
Abstract
Power systems’ increased running costs and overuse of fossil fuels have resulted in continuing energy scarcity and momentous energy gap challenges worldwide. Renewable energy sources can meet exponential energy growth, lower reliance on fossil fuels, and mitigate global warming. An MINLP optimization method [...] Read more.
Power systems’ increased running costs and overuse of fossil fuels have resulted in continuing energy scarcity and momentous energy gap challenges worldwide. Renewable energy sources can meet exponential energy growth, lower reliance on fossil fuels, and mitigate global warming. An MINLP optimization method to solve the RES-hybrid system economic dispatch of electric vehicle charging stations is proposed in this paper. This technique bridges the gap between theoretical models and real-world implementation by balancing technical optimization with practical deployment constraints, making a timely and meaningful contribution. These contributions extend the practical application of MINLP in modern grid operations by aligning optimization outputs with the stochastic character of renewable energy, which is still a gap in the existing literature. The proposed economic dispatch simulation results over 24 h at an hourly resolution show that all generation units contributed proportionately to meeting EVCS demand: solar PV (51.29%), ESS (13.5%), grid (29.92%), and wind generator (8.29%). The RES-hybrid energy management systems at charging stations are designed to make the best use of solar PV power during the EVCS charging cycle. The supply–demand load profile problem dynamic in EVCS are designed to reduce reliance on grid electricity supplies while increasing renewable energy usage and reducing carbon impact. Full article
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24 pages, 5550 KiB  
Article
Energy-Aware Edge Infrastructure Traffic Management Using Programmable Data Planes in 5G and Beyond
by Jorge Andrés Brito, José Ignacio Moreno and Luis M. Contreras
Sensors 2025, 25(8), 2375; https://doi.org/10.3390/s25082375 - 9 Apr 2025
Cited by 1 | Viewed by 998
Abstract
Next-generation networks, particularly 5G and beyond, face rising energy demands that pose both economic and environmental challenges. In this work, we present a traffic management scheme leveraging programmable data planes and an SDN controller to achieve energy proportionality, matching network resource usage to [...] Read more.
Next-generation networks, particularly 5G and beyond, face rising energy demands that pose both economic and environmental challenges. In this work, we present a traffic management scheme leveraging programmable data planes and an SDN controller to achieve energy proportionality, matching network resource usage to fluctuating traffic loads. This approach integrates flow monitoring on programmable switches with a dynamic power manager in the controller, which selectively powers off inactive switches. We evaluate this scheme in an emulated edge environment across multiple urban traffic profiles. Our results show that disabling switches not handling traffic can significantly reduce energy consumption, even under relatively subtle load variations, while maintaining normal network operations and minimizing overhead on the control plane. We further include a projected savings analysis illustrating the potential benefits if the solution is deployed on hardware devices such as Tofino-based switches. Overall, these findings highlight how data plane-centric, energy-aware traffic management can make 5G-and-beyond edge infrastructures both sustainable and adaptable for future networking needs. Full article
(This article belongs to the Special Issue Energy-Efficient Communication Networks and Systems: 2nd Edition)
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31 pages, 10347 KiB  
Article
Green One-Step Synthesis and Characterization of Fluorescent Carbon Quantum Dots from PET Waste as a Dual-Mode Sensing Probe for Pd(II), Ciprofloxacin, and Fluoxetine via Fluorescence Quenching and Enhancement Mechanisms
by Christian Ebere Enyoh, Qingyue Wang, Weiqian Wang, Miho Suzuki, Go Masuda, Daisuke Nakajima and Senlin Lu
Surfaces 2025, 8(2), 24; https://doi.org/10.3390/surfaces8020024 - 3 Apr 2025
Cited by 1 | Viewed by 2000
Abstract
In this study, we report a green, one-step synthesis of fluorescent carbon quantum dots (PET-FCQDs) derived from polyethylene terephthalate (PET) waste using an environmentally friendly pyrolytic method. The PET-FCQDs were systematically characterized using techniques such as UV-Vis spectroscopy, fluorescence spectroscopy, ATR-FTIR, TGA, and [...] Read more.
In this study, we report a green, one-step synthesis of fluorescent carbon quantum dots (PET-FCQDs) derived from polyethylene terephthalate (PET) waste using an environmentally friendly pyrolytic method. The PET-FCQDs were systematically characterized using techniques such as UV-Vis spectroscopy, fluorescence spectroscopy, ATR-FTIR, TGA, and fluorescence microscope, confirming their nanoscale size (2–50 nm), rich functional groups and thermal stability. Thermal stability and dynamics evaluated by the Coats–Redfern method showed endothermic reactions with an activation energy of 88.84–125.05 kJ/mol. Density functional theory studies showed a binding energy, highest occupied molecular orbital, lowest unoccupied molecular orbital, and energy gap of −675.39, −5.23, −5.07, and 0.17 eV, respectively. The as-synthesized PET-FCQDs demonstrated excellent optical properties with quantum yield (Φ) of 49.6% and were applied as a dual-mode fluorescent sensing probe for the detection of Pd2+, ciprofloxacin (CIP), and fluoxetine (FLX) in aqueous systems via fluorescence quenching and enhancement mechanisms. For Pd2+, the fluorescence emission intensity at 470 nm was quenched proportionally to the increasing concentration, while CIP and FLX induced fluorescence enhancement. The Stern–Volmer analysis confirmed strong interaction between the analytes and PET-FCQDs, distinguishing dynamic quenching for Pd2+ and static interactions for CIP and FLX. The method exhibited linear detection ranges of 1–10 mg/L for Pd2+, 50–150 µg/L for CIP, and 100–400 ng/L for FLX, with corresponding limits of detection (LOD) of 1.26 mg/L, 3.3 µg/L, and 134 ng/L, respectively. Recovery studies in spiked tap water and river water samples demonstrated the practical applicability of PET-FCQDs, although matrix effects were observed, particularly for FLX. This work not only highlights a sustainable route for PET waste upcycling but also demonstrates the potential of PET-FCQDs as cost-effective, sensitive, and versatile fluorescent probes for environmental monitoring of heavy metal ions and pharmaceutical pollutants. Further optimization of the sensing platform could enhance its selectivity and performance in real-world applications. Full article
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35 pages, 5368 KiB  
Article
Systematic Optimize and Cost-Effective Design of a 100% Renewable Microgrid Hybrid System for Sustainable Rural Electrification in Khlong Ruea, Thailand
by Montri Ngao-det, Jutturit Thongpron, Anon Namin, Nopporn Patcharaprakiti, Worrajak Muangjai and Teerasak Somsak
Energies 2025, 18(7), 1628; https://doi.org/10.3390/en18071628 - 24 Mar 2025
Cited by 1 | Viewed by 1061
Abstract
This study presents a systematic approach to designing and optimizing a 100% renewable hybrid microgrid system for sustainable rural electrification in Khlong Ruea, Thailand, using HOMER Pro software (Version 3.15.3). The proposed system integrates photovoltaic (PV) panels (20 kW), pico hydro (9.42 kW), [...] Read more.
This study presents a systematic approach to designing and optimizing a 100% renewable hybrid microgrid system for sustainable rural electrification in Khlong Ruea, Thailand, using HOMER Pro software (Version 3.15.3). The proposed system integrates photovoltaic (PV) panels (20 kW), pico hydro (9.42 kW), and lithium-ion battery storage (264 kWh) to provide a reliable, cost-effective, and environmentally sustainable energy solution for a remote village of 306 residents. The methodology encompasses site-specific resource assessment (solar irradiance, hydro flow), load demand analysis, and techno-economic optimization, minimizing the net present cost (NPC) and cost of energy (COE) while achieving zero emissions. Simulation results indicate the optimal configuration (S1) achieves an NPC of USD 362,687 and COE of USD 0.19/kWh, with a 100% renewable fraction, outperforming the current diesel–hydro system (NPC USD 3,400,000, COE USD 1.85/kWh, 61.4% renewable). Sensitivity analysis confirms robustness against load increases (1–5%), though battery capacity and costs rise proportionally. Compared to regional microgrids, the proposed system excels in terms of sustainability and scalability, leveraging local resources effectively. The lifecycle assessment highlights the battery’s embodied emissions (13,200–39,600 kg CO2e), underscoring the need for recycling to enhance long-term sustainability. Aligned with Thailand’s AEDP 2018–2037 and net-zero goals, this model offers a replicable framework for rural electrification in Southeast Asia. Stakeholder engagement, including community input and EGAT funding, ensures practical implementation. The study demonstrates that fully renewable microgrids are technically feasible and economically viable, providing a blueprint for sustainable energy transitions globally. Full article
(This article belongs to the Section A: Sustainable Energy)
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12 pages, 5722 KiB  
Article
Steady Smoldering of Fuel Rods: Relationship Between Propagation Velocity and Fume Thickness on Schlieren Photographs
by Guangxin Yu, Xin Chen, Yi Zhang, Jianwen Zha and Fang He
Processes 2025, 13(4), 954; https://doi.org/10.3390/pr13040954 - 24 Mar 2025
Viewed by 2225
Abstract
The steady smoldering of rod-shaped fuels, a traditional Chinese disinfection and pest control technique, presents unique challenges in theoretical modeling. Conventional analytical approaches based on energy and mass conservation equations form an underdetermined system, failing to uniquely resolve three critical parameters: temperature field, [...] Read more.
The steady smoldering of rod-shaped fuels, a traditional Chinese disinfection and pest control technique, presents unique challenges in theoretical modeling. Conventional analytical approaches based on energy and mass conservation equations form an underdetermined system, failing to uniquely resolve three critical parameters: temperature field, char morphology, and propagation velocity. This study establishes a quantitative relationship between smoldering propagation velocity and smoke schlieren thickness through integrated experimental and theoretical methodologies. Systematic experiments were conducted on vertically oriented fuel rods (upward and downward configurations), measuring propagation velocity, char cone geometries, and schlieren photographs. By incorporating surface oxidation kinetics and oxygen transport mechanisms into a theoretical model, we revealed an inverse proportionality between propagation velocity and schlieren thickness, thereby introducing a third constraint to resolve the system. Comparative analysis demonstrated excellent agreement between calculated and measured velocities for downward smoldering, with deviations below 20% for biomass rods and 60% for commercial incense rods. Significant discrepancies in upward smoldering were attributed to smoke plume entrainment effects. This work enhances the mechanistic understanding of smoldering propagation dynamics in anisotropic fuel systems. Full article
(This article belongs to the Section Particle Processes)
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