Search Results (328)

Seasonal energy storage effectively addresses seasonal electricity supply–demand imbalances. This study proposes a cross-seasonal compressed air energy storage system using a depleted gas reservoir as the storage reservoir. A six-stage compression–expansion system with intercooling and reheating is designed. Also, the heat of compression is recovered for district heating, and the expansion of cold energy is for cooling supply, thereby avoiding cross-seasonal heat storage costs. For the YD1 depleted gas reservoir case, the system achieves a round-trip efficiency of 57.85% and an exergy efficiency of 70.9%. The total energy utilization ratio, which represents the combined utilization of the electricity, heating, and cooling outputs relative to the corresponding energy input, reaches 166.6%. Incorporating revenue from the heating and cooling sales, the dynamic payback period is 2.38 years, and the investment recovery ratio reaches 4.40. Parametric analysis indicates that thermodynamic performance improves with the increase in discharge pressure and decrease in discharge power. Economic performance improves with longer daily operating hours and plant lifetime. This study demonstrates that depleted gas reservoirs combined with well-designed surface combined cooling, heating, and power systems offer a new research and development direction for large-scale, long-duration seasonal storage, facilitating renewable energy integration and grid stability. Full article

Off-grid agricultural cold chains suffer from high energy conversion losses due to intermediate electrical stages in traditional refrigeration. This study addresses the lack of empirical quantification by comparing Direct Mechanical Drive (DMD) and Electrical Power Generation (EPG) drive trains for an R-134a vapor compression refrigeration system. Under steady-state conditions (randomized block design), DMD achieved a statistically significant 13.89% reduction in biomass consumption over EPG (1840.0 vs. 2136.7 g/h; p < 0.001). The biomass consumption was evaluated based on the measured charcoal mass flow under the same lower heating value basis. Conversely, refrigeration COP was statistically equivalent (2.74 vs. 2.73; p = 0.815), confirming that drive-train architecture does not alter internal vapor compression thermodynamics. Only 19.6% of the compressor shaft power appeared as useful fluid-side compression work under this fractional-load operating condition, a volumetric rather than mechanical deficiency arising from operation at 7.7–15.5% of the compressor’s rated capacity. Referenced consistently to the primary biomass chemical energy input, the First-Law biomass-to-cooling system efficiency was 3.66% (equivalent to 5.34% when referenced to the syngas delivered to the engine), with a corresponding biomass-referenced exergy efficiency of 0.44%. Component exergy analysis revealed that the internal combustion engine (59.13% of total exergy destruction, ε = 13.1%) and the gasifier (32.4%, ε = 67.7%) dominated total system exergy destruction (15.49 kW). Furthermore, a 10-year life-cycle cost (LCC) analysis indicates DMD-Syngas yields net present value savings of 21,071.57 USD over gasoline-EPG, yielding a 0.14-year (~50-day) simple payback period on the 400.12 USD net incremental hardware capital cost (the gasification subsystem less the alternator–motor drive train that the direct-drive configuration does not require, and excluding one-time installation and training costs). When the fully installed cost is accounted for—including site preparation, process-water supply and effluent handling, low-voltage provision, installation labor, operator training and contingency—the incremental investment rises to 1298–2405 USD and the payback period extends to approximately 162–301 days. Under the least favorable combination examined, in which commercially purchased charcoal is imposed simultaneously with the upper installed-cost bound, capital recovery extends to approximately 1.4 years; the base case nevertheless recovers the incremental investment within the first operating year. An operational-phase (gate-to-gate) carbon assessment indicates near parity with the gasoline baseline on a strictly attributional basis (+120 to +1200 kg CO₂e yr⁻¹); a net saving of 8880–13,320 kg CO₂e yr⁻¹ arises only under the consequential scenario in which open-field burning of orchard residues is displaced and is further contingent on including black carbon in the accounting basket. This is not a full ISO 14040/44 life-cycle assessment, and the environmental outcome is therefore scenario-dependent rather than intrinsic to fuel substitution. These results demonstrate that mechanical drive-train optimization substantially enhances fuel economy without compromising refrigeration performance, providing a rigorous evidence base for scalable biomass-powered off-grid cold chains. Full article

Post-disaster emergency logistics is often organized according to prespecified response periods, although operational relief tasks may be completed earlier or later than those calendar boundaries. This study develops a task-completion-triggered multi-stage resource-allocation mechanism (TCMS) for a two-echelon emergency logistics network. Effective first-contact coverage and cumulative forward deployment generate three sequential operational stages—rapid coverage, intensive deployment, and recovery support—through a one-period state-update rule. The operational stage determines the priority regime used to select among feasible allocation schedules. The mechanism is evaluated within a common direct-decision rolling-horizon mixed-integer linear programming (MILP) framework. At each decision epoch, policy-neutral cost-service candidates are generated using total cost and cumulative raw weighted backlog, whereas the current operational stage supplies stage-dependent priority coefficients for selecting the implemented action. TCMS and a fixed-stage baseline therefore differ in the source of their operational stage, while a stage-free rolling-horizon benchmark retains a neutral priority regime. Computational experiments include formulation validation, Base and Medium rolling-horizon policy comparisons, a Large static MILP reference, and trigger-parameter and stage-priority-coefficient sensitivity analyses. The results show that endogenous stage timing changes the selected cost-service operating point, with effects varying across instances. Sensitivity analysis further shows that transition timing and allocation outcomes can vary with trigger settings and stage-priority calibration. TCMS is particularly suited to settings in which transition timing cannot be specified reliably in advance, and managers require an observable basis for adjusting allocation priorities as relief operations progress. Full article

Warming is making drought and heat co-occur more often, intensifying compound stress on cropland in northern China’s drylands, where water scarcity makes further irrigation expansion untenable. On the Guanzhong Plain, a major grain-producing region, it remains unclear which irrigation conditions buffer cropland carbon–water productivity—the carbon assimilated per unit of water consumed—against such events. Using growing-season (March–October) remote sensing for 2016–2024, we identified the 2022 compound drought–heat event pixel by pixel and classified cropland as stable rainfed, transitional/mixed, or stable high-coverage irrigation from the pre-event (2016–2020) irrigated-area fraction and its persistence. In 2022, 88.9% of cropland experienced at least one compound dry–hot day, with dry–hot overlap 2.4 times the independence expectation. After balancing climate, terrain, soil, spatial position, and subpixel cropland fraction, stable high-coverage irrigation held no advantage in event-year resistance, post-event recovery, or overall resilience. Carbon assimilation remained above its pre-event level while carbon–water productivity fell, so the event cost water-use efficiency rather than carbon. Event-period root-zone soil-moisture change ranked first, and irrigated-area fraction last, among twelve random-forest predictors of resistance. We flagged 6722.3 km² of cropland for water-use audits and 2418.1 km² for supplemental irrigation; limited water should be allocated by realized moisture status, exposure, and resilience, not by irrigability. Full article

Multi-energy virtual power plants (VPPs) aggregate electricity, heating, and natural gas resources to provide flexible regulation services to the external power grid. Their operational flexibility, however, cannot be accurately characterized using equipment capacities or single-period energy balances alone, because district heating and natural gas networks introduce heat transport delays, pipeline thermal storage, pressure dynamics, and linepack effects. This paper proposes an operational flexibility boundary assessment method for electricity–heating–gas VPPs based on a dynamic energy circuit model (ECM). The frequency-domain ECM converts heating-network temperature dynamics and gas-network pressure dynamics into algebraic constraints, which are integrated with electric-network and multi-energy coupling-device constraints. The net exchange power at the point of common coupling (PCC) is used as the external flexibility interface, and the period-wise upper and lower boundaries are determined subject to network and device constraints, terminal-state recovery requirements, and an economic feasibility limit. Case studies on an electricity–heating–gas VPP demonstrate that the dynamic ECM captures the intertemporal regulation capability provided by pipeline thermal storage and gas-network linepack. Compared with the static model, the dynamic ECM exhibits consistently greater downward flexibility and comparable or lower upward flexibility in several periods, thereby correcting the underestimation of electrical absorption capability and the optimistic estimation of power-export capability caused by the static approximation. The economic feasibility constraint further excludes high-cost boundary schedules, yielding a technically feasible and economically acceptable flexibility range. Full article

Background: Effective opioid-sparing analgesia after median sternotomy remains an unmet need in cardiac surgery. We evaluated whether bilateral intercostal cryoanalgesia, added to standard multimodal analgesia, was associated with postoperative pain, opioid consumption, recovery and early hospital-resource use after isolated coronary artery bypass grafting (CABG). Methods: This single-centre, non-randomised comparative service evaluation included 60 patients undergoing isolated CABG through median sternotomy between 1 November 2025 and 30 May 2026 (30 cryoanalgesia; 30 standard care). The prespecified primary endpoint was cumulative movement-evoked pain burden, quantified as the area under the curve (AUC) for scores recorded on postoperative days 1–3. Secondary endpoints included rest-pain AUC, opioid consumption expressed as oral morphine equivalents (OME), time to first bowel opening, postoperative length of stay and an exploratory break-even calculation. Results: Cryoanalgesia was associated with lower movement-pain AUC (adjusted mean difference −3.56 score-days, 95% confidence interval [CI] −4.62 to −2.50; p < 0.001) and rest-pain AUC (−3.16 score-days, 95% CI −4.19 to −2.14; p < 0.001). Total observed opioid consumption was lower by 112.9 mg OME (95% CI −192.8 to −33.1; p = 0.006), length of stay by 1.32 days (95% CI −1.93 to −0.71; p < 0.001), and time to first bowel opening by 0.49 days (95% CI −0.92 to −0.06; p = 0.027). Conclusions: In this small non-randomised evaluation, bilateral intercostal cryoanalgesia was associated with lower early pain and opioid exposure and faster recovery. Selection, temporal and residual confounding preclude causal or cost-effectiveness conclusions. Prospective randomised evaluation with fixed observation periods and longer-term safety follow-up is required. Full article

This research presents a straightforward and detailed method for calculating the cost of recycling solar panels and the associated economic benefits. The contribution of this research is to estimate the impact of the recycling process on the cost of energy and the payback period. The Full Recovery End-of-Life Photovoltaic (FRELP) method was utilized to assess the PV recycling process. Calculations were made for every 1000 kg of solar panels and converted to calculate the cost and revenue per square meter of panels. Calculations showed that the cost of recycling in Saudi Arabia reached 9.46 $/m² based on the geographical environment, fuel prices, and the various materials used in recycling processes, while the revenue was approximately 24.6 $/m² according to the current prices of materials resulting from the recycling process, especially the price of silver. The study results were applied to a 400 MW solar power plant to determine the feasibility of recycling the energy price and the payback period. The solar power plant was designed using variable-sized solar panels with capacities of 255, 330, and 580 watts. The recycling revenue for the plant with the smaller panels was the highest, being $2.6 M as an annual rate. Full article

Continuous carbon anode roasting in industrial parks requires a stable high-temperature heat supply and remains highly dependent on grid electricity and natural gas. However, existing energy-system studies rarely coordinate hydrogen production and storage, volumetric hydrogen blending, and temperature-graded waste-heat recovery under continuous production constraints. To address this gap, this study proposes an electricity–heat–gas–hydrogen integrated energy system for carbon anode industrial parks and develops a 24 h multi-objective scheduling model. The model coordinates heat demands at different temperature levels with hourly electricity and hydrogen flows, using surplus photovoltaic power to produce hydrogen for later high-load periods. The selected scheme achieves a daily volumetric hydrogen-blending ratio of 10.79%, with an operating cost of 82,985.75 CNY and carbon emissions of 54,371.53 kg. Relative to an otherwise equivalent non-hydrogen configuration, hydrogen coupling provides additional reductions of 7.2% in operating cost and 2.3% in carbon emissions. Compared with a basic conventional configuration, operating cost and carbon emissions decrease by 27.9% and 26.0%, respectively. Cascade recovery also increases the daily waste-heat utilization rate by approximately 30 percentage points. These results show that the proposed scheduling framework can coordinate hydrogen utilization and graded waste-heat recovery while maintaining continuous carbon anode production. Full article

Background/Objectives: Hypertension remains one of the leading modifiable risk factors for cardiovascular disease worldwide. Although exercise is widely recommended as a first-line non-pharmacological intervention, adherence to conventional exercise programs is often limited. Isometric training, particularly wall squat exercise, has emerged as a promising alternative for blood pressure (BP) management. This study evaluated blood pressure changes following a 12-week isometric wall squat training program in adults with hypertension and explored whether these changes differed according to subsequent antihypertensive medication initiation. Methods: A quasi-experimental longitudinal study was conducted in 119 adults with medically diagnosed hypertension. Participants completed a 12-week isometric wall squat training program consisting of three weekly sessions, each including four 2 min contractions separated by 2 min recovery periods. Blood pressure was assessed at baseline, week 8, and week 12 using standardized procedures. Mixed repeated-measures analysis of variance (ANOVA) was performed to assess changes over time in systolic blood pressure (SBP) and diastolic blood pressure (DBP), with antihypertensive medication initiation included as a between-subject factor. Results: Mean blood pressure progressively decreased throughout the intervention. Mean SBP decreased from 148.0 ± 7.1 mmHg at baseline to 132.0 ± 10.7 mmHg at week 12 (Δ = −16.0 mmHg), whereas mean DBP decreased from 94.4 ± 4.9 mmHg to 85.1 ± 5.6 mmHg (Δ = −9.3 mmHg). Significant main effects of time were observed for both SBP (F = 321.61, p < 0.001, ηp² = 0.733) and DBP (F = 191.60, p < 0.001, ηp² = 0.621). No significant time × antihypertensive medication initiation interaction was observed for either SBP (p = 0.526) or DBP (p = 0.126). Conclusions: A 12-week isometric wall squat training program was associated with clinically meaningful reductions in systolic and diastolic blood pressure in adults with hypertension. These findings suggest that isometric wall squat exercise may represent a feasible, low-cost, and time-efficient complementary strategy for non-pharmacological blood pressure management. However, because of the quasi-experimental design and the absence of a control group, randomized controlled trials are needed to confirm these findings and establish the effectiveness of this intervention. Full article

Tropical cyclones reduce port capacity and leave heterogeneous congestion. Yet empirical measurements of port resilience are rarely connected to operational strategy evaluation on the same observed event baseline. This study develops a dual-layer framework that measures event-level operational resilience under prevailing practice and estimates modelled marginal improvements from three operational levers. Aggregate baseline measures calibrate multi-server queues for 28 ports without event-period tuning, and discrete-event simulation replays 178 port-event trajectories. The calibrated representation places heterogeneous ports on a common queueing scale. Measured states are benchmarked against a dynamic four-hour business-as-usual (BAU) baseline that retains normal temporal variation. During exposure, median service-capacity loss reaches 0.627, and sustained operational-capacity restoration is confirmed after a median 44 h. Service-focused recovery (SES), coordinated recovery (CRS), and two-stage proactive–reactive response (TPRS) are compared after matching costs within each event. CRS gives the largest mean reduction in cumulative queue burden under the base-case cost coefficients and ranks first in 113 of 128 cost-sensitivity scenarios. SES leads when capacity coordination becomes sufficiently expensive, while TPRS becomes more competitive under prolonged, high-loss exposure. The framework supports strategy assessment according to event state, operational feasibility, and implementation cost. Full article

Under the impact of earthquakes, substation systems may experience equipment failures, prolonged functional recovery periods, and expanded power outage consequences. This paper proposes a collaborative optimization framework for enhancing the seismic performance of substation systems and deploying repair resources, aimed at pre-earthquake planning. The system function is characterized by the outage availability of feeders weighted by load and user importance, and the user outage cost is explicitly defined as an economic consequence indicator with monetary units, rather than a dimensionless resilience index. A directed graph model is constructed to simulate the post-earthquake functional recovery process, and under given seismic hazard and vulnerability parameters, Monte Carlo sampling is used to capture the randomness of equipment condition failures and repair durations. Sensitivity analysis is employed to identify critical equipment, and the elitism-preservation and adaptive evolution non-dominated sorting genetic algorithm II (ERA-NSGA-II algorithm), which integrates heuristic initialization, adaptive evolution, and diversity maintenance mechanisms, is proposed to achieve joint optimization of repair teams and equipment reinforcement plans. A typical 220 kV substation case study demonstrates that the framework is feasible under the analyzed scenarios and exhibits better empirical search performance compared to the selected benchmark algorithm. Due to the limitations of a single topology and certain fixed input parameters, the obtained results are scenario-dependent and cannot be used to infer general applicability or global convergence. Full article

The post-pandemic recovery of the hotel sector has been primarily associated with revenue growth; however, there is limited evidence on how this process translates into the generation of financial value. The aim of this study was to carry out a descriptive and exploratory financial analysis to examine how commercial growth translates into sustainable financial results in four-star hotels in the province of Imbabura, Ecuador, during the period 2019–2023. The research was carried out using a descriptive and exploratory financial analysis based on a ‘small-sample financial diagnostics’ approach, involving a longitudinal analysis of 45 firm-year observations (nine hotels × five years), compiled from complete and comparable public financial statements for the period 2019–2023. The data was organised by hotel and year, enabling an analysis of trends in operating revenue, the structure of costs and expenses, operating profit, net profit, net margin, and, as supplementary indicators, immediate liquidity, return on assets, and indebtedness. The results show that the recovery in revenue did not uniformly translate into an improvement in financial performance due to differences in operational structure and in the capacity to generate sustainable profits. As a contribution, the study proposes an integrated approach to financial diagnosis that broadens our understanding of the process by which commercial growth may or may not translate into the generation of sustainable financial value in emerging tourist destinations. Full article

Background/Objectives: Recovery nutrition must restore near-term readiness without indiscriminately suppressing biological signals that contribute to repair and training adaptation. This review evaluates recovery–adaptation coupling (RAC) as a research framework and clarifies its contribution relative to established recovery, nutrient-periodization, and athlete-monitoring models. Methods: Targeted narrative searches of PubMed/MEDLINE, Scopus, and Web of Science were supplemented by Google Scholar citation tracking and backward and forward screening. Peer-reviewed English-language literature available through 31 May 2026 was considered. Human athlete studies, randomized trials, systematic reviews, meta-analyses, consensus statements, and position stands were prioritized; mechanistic evidence was used to explain pathways rather than to support stand-alone performance recommendations. The final cited corpus comprised 130 records. No formal risk-of-bias tool, certainty grading, PRISMA denominator, or quantitative pooling was used. Claims were instead identified as established practice (EP), context-dependent evidence (CDE), mechanistic rationale (MR), or RAC hypothesis (RH). Results: The most consistent applied support concerns adequate energy availability, distributed high-quality protein, carbohydrate restoration when recovery windows are short, and individualized fluid and sodium replacement. Evidence for polyphenol-rich products, curcumin, omega-3 fatty acids, and creatine is context- and product-dependent. Collagen or gelatin evidence is mainly mechanistic or pilot-level, while RAC recovery-pattern categories and multimodal monitoring rules remain unvalidated hypotheses. RAC differs from existing frameworks by jointly specifying the next athletic demand, dominant recovery bottleneck, possible adaptive cost of intervention, and response-verification plan. Conclusions: RAC should presently be interpreted as an evidence-organization and hypothesis-generation architecture, not as a validated predictive, diagnostic, or treatment algorithm. Prospective comparative studies are required before RAC-specific decision rules can guide individualized practice. Full article

Silica gel is extensively used as a desiccant for dehumidifying methane gas during natural gas treatment operations. Over time, the adsorbent becomes saturated with total petroleum hydrocarbons (TPHs), including saturated, unsaturated, and aromatic compounds, rendering it ineffective. This study presents a laboratory-scale bioremediation technology employing a consortium of non-pathogenic bacterial strains (Bacillus amyloliquefaciens, Bacillus pumilus, Bacillus subtilis, and Bacillus macerans) combined with a nutrient supplement to degrade TPH compounds adsorbed on silica gel granules. Three replicate experiments were conducted over 42 days with periodic aeration and partial water replacement every three days. The initial TPH concentration of 1309.06 mg/kg was reduced to 1.006 mg/kg after 42 days, corresponding to a removal efficiency of 99.92%. TPH degradation followed first-order kinetics (k = 0.192 day⁻¹, R² = 0.987, t₁/₂ = 3.6 days). Water adsorption capacity of the treated silica gel was 28% w/w compared to 35% w/w for virgin material, representing an 80% recovery of desiccant performance. These results demonstrate that biological remediation constitutes a cost-effective and environmentally sound alternative to landfill disposal of spent silica gel in the natural gas industry, with strong potential for industrial scale-up. Full article

The rapid growth of graphics processing unit (GPU)-accelerated AI workloads has made data centers significant sources of medium-grade waste heat, creating both a sustainability challenge and an urban decarbonization opportunity. This paper presents the Cascaded Exergy-Economic Valorization (CEEV) framework, a three-stage system that converts data-center waste heat through (1) an organic Rankine cycle for GPU liquid-cooling loops at 65–85 °C; (2) a transcritical CO₂ heat pump, upgrading residual heat to 75–90 °C; and (3) thermochemical energy storage using SrBr₂·6H₂O for seasonal heat banking. The framework introduces two metrics: the Exergy Value Index (EVI, $/kJ) and the Levelized Cost of Stored Heat (LCSH, $/kWhth). Results for a 10 MW liquid-cooled data center across three climate zones show cascade exergy utilization of 31.2–38.7%, operational cost reductions of 15–25%, 20-year NPV of $2.2–8.4 million, and payback periods of 5.8–7.8 years. The simpler HP (heat pump) +TCES (thermochemical energy storag) configuration achieves higher deterministic Net Present Value (NPV) because it preserves the full waste-heat temperature for the heat pump; however, the full three-stage cascade becomes preferable when electricity prices exceed approximately $50/MWhe, when revenue diversification is valued, or when real-options flexibility is important. Real-options analysis shows that traditional NPV undervalues cascaded waste-heat recovery investments by 18–32%. Even without carbon credit revenue, NPV remains positive at $1.6–6.1 million, confirming that district-heating sales and electricity revenue alone can support investment. The CEEV framework advances sustainable data-center development by providing quantifiable tools for waste-heat performance assessment, supporting policy instruments such as the EU Energy Efficiency Directive and the German EnEfG, and aligning with SDGs 7, 9, 11, and 13. Full article