Search Results (3,378)

The Hwange Mining Area, located in the Mid-Zambezi Karoo Basin in northwestern Zimbabwe, is a major centre for coal mining, processing, and thermal power generation. This study evaluates the ecological and public health risks associated with these activities by characterising radionuclide (²²⁶Ra, ²³²Th, ⁴⁰K) activity concentrations in coal and surrounding soils using Hyper-Pure Germanium (HPGe) gamma spectrometry. Samples were collected from four locations, as follows: Hwange Colliery Company (underground and open-cast mines), Zambezi Gas open-cast operations, residential areas, and the Zimbabwe Power Company (ZPC) thermal power station. Radionuclide concentrations were measured using Hyper-Pure Germanium (HPGe) gamma spectrometry. Mean activity concentrations in coal were low at both mining sites (Hwange Colliery: ²²⁶Ra 16 ± 5.3 Bq/kg), ²³²Th 14 ± 5.7 Bq/kg), (⁴⁰K 51 ± 8.8 Bq/kg) and Zambezi Gas (²²⁶Ra 9.80 ± 2.3 Bq/kg), ²³²Th (11 ± 3.3 Bq/kg), ⁴⁰K (43 ± 26 Bq/kg), well below UNSCEAR world coal averages. In contrast, soils from residential areas): ²²⁶Ra (36 ± 15 Bq/kg), ²³²Th (36 ± 12 Bq/kg) and ⁴⁰K (220 ± 80 Bq/kg), and the ZPC power station (²²⁶Ra 47 ± 8.6 Bq/kg, ²³²Th (42 ± 10 Bq/kg), and ⁴⁰K 230 ± 92 Bq/kg, showed markedly elevated concentrations, consistent with the accumulation of coal-combustion by-products such as fly ash. Radiological hazard indices remained within internationally accepted limits at all sites, as follows: radium equivalent (Raeq) ranged from 29 ± 6.7 Bq/kg (Zambezi Gas) to 120 ± 18 Bq/kg (ZPC), well below the 370 Bq/kg safety ceiling, while external and internal hazard indices (H_ex, H_in) remained below unity throughout, peaking at 0.32 and 0.46, respectively, at ZPC. Annual effective dose equivalents (AEDE) ranged from 16 ± 3.8 to 69 ± 10 μSv/year, the latter (ZPC) representing approximately 7% of the ICRP public dose limit of 1 mSv/year. Excess lifetime cancer risk (ELCR) values ranged from 5.56 × 10⁻⁵ (Zambezi Gas) to 2.42 × 10⁻⁴ (ZPC), remaining below the global average outdoor reference of 0.29 × 10⁻³ but reaching approximately 83% of this reference at ZPC and 71% in residential areas. These findings indicate that, while coal mining activities in Hwange contribute minimally to environmental radioactivity, coal combustion at the ZPC thermal power station is the dominant driver of elevated radionuclide concentrations and radiological indices in the surrounding environment, with residential soils reflecting the same enrichment pathway. Although no immediate radiological hazard was identified at any location, the comparatively higher indices at ZPC and in nearby residential areas underscore the need for continuous environmental monitoring, strengthened regulatory control, and targeted radiation protection strategies to safeguard workers and nearby communities. Full article

Mine leachate and saline industrial wastewater streams are often treated as liabilities to be remediated or disposed of. These flows often contain substantial water and dissolved mineral resources that can be reclaimed. In this work, a waste-heat-assisted falling-film evaporation reactor was developed and assessed for application as a pre-concentration step before water and mineral recovery processes. Two case studies were considered: synthetic saline wastewater containing 80 g/L Na₂SO₄ and 70 g/L NaCl for salt recovery, and iron-rich mine water containing approximately 4000 mg/L Fe²⁺, 95 mg/L Fe³⁺, and 13,000 mg/L acidity as CaCO₃ for downstream pigment and magnetite recovery. Saline water or mine leachate flows down a bank of vertical conduit pipes as a thin film while air flows through the pipe cores. Heat is transferred to the system from industrial waste gas externally. Psychrometric relationships, heat transfer, energy balances, and techno-economic analysis were used to assess the impact of air temperature, conduit diameter, column height, pipe material, and waste-gas temperature on overall reactor performance. Experiments were carried out to confirm expected psychrometric operation and establish appropriate operating temperatures while confirming the impact of conduit geometry on heat-transfer characteristics. A benchmark case of design evaporation rate equal to 100 L/h was chosen for comparison of all tests. Dry air operation was shown to be technically possible but severely limited by the moisture capacity of air; at 26 °C and 101.3 kPa, approximately 205,000 m³/h of air was required. When using industrial waste heat, the operation changed from psychrometric/mass-transfer-limited to heat-transfer-controlled. Using waste gas entering at 144 °C and exiting at 80 °C reduced airflow requirements to approximately 880 m³/h, allowing a much more compact reactor design with approximately 635 (12 mm diameter) conduit pipes. Relative to the 40 °C air benchmark, electrical power was reduced from approximately 24.7 kW to 2.9 kW, and screening-level reactor cost by ~84%. Findings demonstrated that appropriate waste heat enables the application of evaporation if there is sufficient local heat flux. Smaller conduit diameters, sufficient column height, and greater waste-gas inlet temperatures were all beneficial. Choice of material required trade-offs between heat-transfer coefficient, corrosion, and material cost. Full article

Permanent Magnet Synchronous Motors (PMSMs) are widely employed in electric vehicle (EV) propulsion systems because of their high efficiency, high power density, and superior dynamic performance. The performance of field-oriented control (FOC)-based PMSM drives strongly depends on accurate tuning of the proportional–integral (PI) controllers governing the speed and current loops. Conventional tuning approaches often optimize a single performance index and therefore fail to simultaneously enhance the dynamic behavior of all control loops. This paper proposes a multi-error Integral of Time-weighted Absolute Error (ITAE)-based optimization framework for simultaneous tuning of the PI controllers by minimizing a composite objective function that incorporates the time-weighted absolute errors of the rotor speed, q-axis current, and d-axis current. To validate the effectiveness and optimizer independence of the proposed framework, five metaheuristic optimization algorithms—Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Gray Wolf Optimizer (GWO), Gazelle Optimization Algorithm (GOA), and White Shark Optimization (WSO)—are evaluated under identical optimization settings. MATLAB/Simulink simulations are performed for reference-speed tracking, load disturbance rejection, and variable-speed operation. The results demonstrate that the proposed optimization framework consistently improves tracking accuracy and dynamic response regardless of the selected optimizer, while WSO provides the best overall performance. In the variable-speed tracking scenario, WSO achieved the lowest RMSE of 0.96 rad/s and the minimum ITAE value of 0.1716, confirming its effectiveness as the most suitable optimizer for the proposed framework in high-performance PMSM drive applications. Full article

Background/Objectives: Caesarean section (CS) is the most frequently performed abdominal operation worldwide, and surgical technique continues to evolve to reduce peri-operative morbidity. Electrosurgery is now used in the majority of surgical procedures because it allows simultaneous tissue dissection and haemostasis, yet its systematic use during the abdominal-wall phase of CS remains debated, mainly because of concerns about neonatal safety and uncertain benefit in reducing maternal blood loss. This retrospective study aimed to compare the use of an electrosurgical unit with the conventional cold scalpel in women undergoing elective CS. The primary endpoint was maternal blood loss before hysterotomy; the secondary endpoint was the short-term neonatal effect assessed through umbilical cord blood gas analysis. Methods: We retrospectively reviewed 40 elective caesarean sections performed at a tertiary referral centre between September 2024 and May 2025. In 24 procedures (cold scalpel group), the abdominal wall was opened with a cold scalpel, whereas in 16 procedures (ESU group) an electrosurgical unit was used to dissect the subcutaneous abdominal tissues and the muscle fascia and to achieve subcutaneous haemostasis. Blood loss was quantified by weighing laparotomy gauze and by graduated suction. Continuous variables were compared with Student’s t-test for independent samples. Results: The distribution of pre-hysterotomy blood loss departed from normality in both groups (Shapiro–Wilk p < 0.001 and p = 0.003), and the comparison was therefore performed with the Mann–Whitney U test. Pre-hysterotomy blood loss was significantly lower in the ESU group (median 32.5 mL, IQR 25–50) than in the cold scalpel group (median 60 mL, IQR 50–75; Hodges–Lehmann difference −25 mL, 95% CI −45 to 0; p = 0.025; rank-biserial r = 0.42). Differences in haemoglobin, red blood cell and platelet counts measured 24 h after CS did not reach statistical significance (p = 0.27, 0.70 and 0.66, respectively), nor did total blood loss (p = 0.23). Umbilical cord blood gas analysis showed a mean pH of 7.29 ± 0.06 in the ESU group and 7.26 ± 0.08 in the cold scalpel group (p = 0.55), with comparable Apgar scores. Conclusions: In this retrospective series, the use of an electrosurgical unit during the abdominal-wall phase of elective CS was associated with a significant reduction in blood loss up to hysterotomy, with no detectable short-term effect on the neonate. Given the retrospective, non-randomised design and the limited sample size, these findings are hypothesis-generating and require confirmation in adequately powered randomised or prospective studies. Full article

The decarbonization of maritime transportation requires shipboard energy systems to coordinate conventional generators, renewable energy sources, energy storage devices, and thermal energy units under voyage-dependent operating constraints. This paper develops a configurable hybrid multienergy ship system for coordinated electrical and thermal energy scheduling. The proposed framework functionally separates the propulsion subsystem from the service and thermal subsystem while retaining system-level coordination among photovoltaic generation, wind generation, diesel generators, micro gas turbines, energy storage batteries, and thermal energy units. A convolutional neural network is employed to provide short-term photovoltaic power forecasts for day-ahead scheduling. The resulting scheduling problem simultaneously considers voyage completion, power balance, equipment operating limits, ramp-rate constraints, battery charging and discharging restrictions, operating costs, and pollutant emission treatment costs. The nonlinear operating logic is reformulated as a mixed-integer optimization problem and solved using CPLEX. A representative coastal voyage case study is used to evaluate the proposed framework. The results demonstrate that the method can coordinate multiple shipboard energy sources, satisfy the prescribed electrical and thermal demands, and provide a set of Pareto-optimal solutions describing the trade-off between operating cost and emission-related cost. The proposed framework provides a system-level scheduling approach for supporting the economic and low-carbon operation of hybrid multienergy ships under increasingly stringent maritime emission reduction requirements. Full article

The increasing penetration of renewable energy has significantly intensified the demand for flexible operation of thermal power plants, making dynamic simulation an essential tool for understanding transient behaviors and developing advanced operational strategies for circulating fluidized bed (CFB) power plants. This review critically examines the existing dynamic modeling approaches for industrial-scale CFB power plants, with particular emphasis on their applicability to flexibility studies. Existing CFB flue-gas side models are systematically classified into three categories: 3D physics-based CFD models, behavioral/data-driven models, and semi-empirical mechanistic models. Their characteristics are critically compared in terms of spatial and temporal scales, empirical dependence, model generality, computational and implementation burden, and applicability to CFB flexibility studies. Dynamic modeling of the steam–water cycle is also reviewed, showing that it has reached a relatively mature stage owing to well-established thermo-hydraulic theories and standardized modeling platforms. The current research bottleneck is therefore identified as the dynamic coupling between the flue-gas side and the steam–water cycle for integrated CFB whole-plant simulation. Based on the comparative analysis, semi-empirical mechanistic models are identified as a particularly suitable framework for industrial-scale CFB flexibility studies requiring minute-to-hour transient simulation, physical interpretability, and whole-plant coupling. Finally, future research directions are discussed, highlighting how integrated dynamic models can support CFB flexibility-enhancement technologies and the development of new-generation coal-fired power plants. 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

Coal-fired power plants equipped with selective catalytic reduction (SCR) and wet flue-gas desulfurization (WFGD) can co-control mercury, but performance is limited by incomplete upstream Hg⁰ oxidation and downstream re-emission. This study evaluated a 660 MW unit using gas-, liquid-, and solid-phase measurements and coordinated single-factor and coupled operating tests. Under baseline conditions, SCR Hg⁰ oxidation was 31.66%, WFGD Hg²⁺ capture was 73.79%, and net mercury removal was 31.08%, with a stack Hg^T concentration of 4.70 µg/Nm³. Coupled optimization increased SCR Hg⁰ oxidation to 69.76% and WFGD Hg²⁺ capture to 96.05%, reduced the re-emission index from 0.596 to 0.250, and raised net removal to 70.83%. SCR inlet temperature, equivalent space velocity, and catalyst health were the dominant upstream factors, while S(IV), oxidation–reduction potential (ORP), slurry pH, and oxidation air supply governed downstream stabilization. A practical operating window was identified near 340 °C, with a normalized stoichiometric ratio (NSR) of approximately 1.0, high ammonia injection uniformity, pH of 5.5–6.0, ORP of approximately 200 mV, and S(IV) of approximately 2 mmol/L. The results show that coordinated operation of existing SCR–WFGD equipment can substantially reduce stack mercury without dedicated mercury-control hardware, provided that NH₃ slip, SO₃-related risk, catalyst condition, and absorber stability are simultaneously constrained. Full article

A fractional-order image enhancement and fractal complexity-guided fusion method was developed to improve weak fault representation and introduce complexity-aware priors into dissolved gas analysis (DGA)-based diagnosis of oil-immersed power transformers. Gas-ratio features derived from five characteristic gases were combined into an extended DGA feature sequence and converted into two-dimensional representations using the Markov transition field (MTF), recurrence plot (RP), and Gramian angular field (GAF). A fractional-order difference operator then strengthened texture details and local variations, while fractal complexity features quantified structural irregularities across fault conditions. Based on these features, a fractal complexity-guided multi-image attention fusion module was designed to adaptively integrate the three image representations. An improved RIME optimization algorithm was further employed to jointly optimize the fractional order, imaging parameters, and network hyperparameters. On the public DGA dataset, the proposed model achieved precision, recall, accuracy, and F1-score values of 97.68%, 97.51%, 97.82%, and 97.71%, respectively. External validation on a self-collected DGA dataset further demonstrated its robust cross-condition generalization capability. Full article

Integrated electricity–gas–heat systems require coordinated scheduling while limiting data sharing and representing network constraints. This paper develops a day-ahead model incorporating reactive power, voltage magnitudes, network losses, demand response, and CHP/P2G coupling. Piecewise linearization and second-order cone relaxation reformulate the model as a mixed-integer second-order cone program, while a hierarchical ATC–ADMM method coordinates the electricity–heat and natural gas subsystems by exchanging coupling variables. Residual checks verify approximation accuracy and original equation feasibility. In the test system, ATC–ADMM reached consensus within five iterations, with a total-cost deviation of 0.0075% from centralized optimization, whereas ATC did not converge within 500 iterations. Coordinated operation reduced the total cost by 1.13%, and Shapley allocation benefited both subsystems. Increasing demand-side flexibility from 5% to 9% reduced the total cost by 0.88% and wind curtailment from 6.02% to 4.86%; increasing reactive compensation from 40% to 60% reduced the total cost by 0.41% and wind curtailment to 5.70%. The results reveal non-monotonic penalty-update effects and diminishing marginal benefits of flexibility resources, providing guidance for parameter selection and capacity allocation. Full article

As variable renewable generation grows, intermittent dispatch of run-of-river hydropower plants may transfer required environmental-flow releases from turbines to spillways, creating conditions that favor total dissolved gas (TDG) supersaturation and may constrain hydropower flexibility. This study presents a reproducible basin-scale screening assessment for 24 selected hydropower plants in the Brazilian Amazon and Tocantins–Araguaia basins. The analysis combines a plant inventory, spillway typology, standardized environmental-flow scenarios, and two configuration-specific linear relationships between unit discharge and the increase in TDG saturation (ΔTDG), derived from digitized Pubugou and Gongzui observations. Two release configurations were examined: flow distributed among all available bays and flow concentrated in a single bay as a theoretical hydraulic bounding case. The Pubugou-based relationship was applied only to broadly comparable ski-jump configurations within 9.1 ≤ UD ≤ 72.3 m³ m⁻¹ s⁻¹, whereas the Gongzui-based relationship was provisionally assigned, as an inventory-level first-order analog, to controlled spillways discharging into stilling basins within 34.6 ≤ UD ≤ 234.6 m³ m⁻¹ s⁻¹. Hydraulically dissimilar cases were classified as NE-H, and cases outside the applicable empirical domain as NE-UD. Digitization sensitivity, regression uncertainty, and model-form selection were explicitly evaluated and documented. None of the distributed-flow scenarios produced a numerical estimate: cases assigned to the Pubugou- or Gongzui-based relationships were classified as NE-UD, whereas hydraulically dissimilar free-surface cases were classified as NE-H. Four single-bay scenarios produced configuration-specific $\Delta \mathrm{T}\mathrm{D}\mathrm{G}$ increments: 22.5–33.4 percentage points for three Gongzui-based cases and 13.6 percentage points for one Pubugou-based case. Upstream TDG was not added, and no plant-specific final concentration or universal ranking was reported. Sinop and Colíder observations were retained as qualitative contextual evidence of limited transferability and the importance of site-specific hydraulics. The outputs support conditional monitoring prioritization under standardized assumptions, not compliance prediction, ecological-risk assessment, or gate-operation recommendations. Synchronized monitoring and plant-specific rating curves are required before TDG-related variables can be incorporated into operational planning. Full article

Ammonia, a toxic and volatile pollutant commonly found in chemical industrial environments, requires reliable real-time detection to ensure industrial safety and effective environmental monitoring. Conventional gas sensors typically operate at elevated temperatures, resulting in high power consumption. Moreover, pure metal oxides and conductive polymers often suffer from significant aggregation and exhibit suboptimal sensing performance under ambient conditions, limiting their practical applications. In this study, hierarchical porous V₂O₅/PANI composites were synthesized via a straightforward one-step coprecipitation method combined with in situ polymerization. The interlaced architecture of polyaniline (PANI) and vanadium pentoxide (V₂O₅) effectively reduces structural aggregation and increases the availability of surface active sites. Furthermore, the synergistic interaction at the bi-phase interface significantly enhances charge carrier transport, leading to improved ammonia-sensing capabilities at room temperature. Notably, the composite containing 20% V₂O₅ demonstrated superior response, selectivity, and reproducibility toward 10 ppm NH₃. Due to its simple fabrication process and room-temperature operation without external heating, the developed V₂O₅/PANI composite sensor holds significant potential for practical applications in low-concentration ammonia detection under ambient conditions. Full article

Underground gas storage (UGS) facilities serve to balance natural gas networks within a given area. The nature of natural gas network balancing is twofold: long-term (seasonal) during periods of significant gas withdrawal (the cold half-year) and short-term (daily) during periods of peak natural gas demand throughout the day. The first type of balancing has been a standard characteristic for many years, covering increased demand during the winter season. In contrast, the importance of daily balancing is growing alongside the ongoing energy transition, where natural gas-based power generation sources flexibly replace renewable energy sources that are dependent on the time of day or weather conditions. The necessity for increased balancing of energy systems makes them more sensitive to crisis situations. This article presents the key role of UGS as a fundamental resilience factor for European energy systems, particularly in the face of energy crises triggered by geopolitical instability. Conflicts are redefining the role of UGS as a pillar of energy security. This study analyzes how strategic gas reserves mitigate the effects of sudden supply disruptions and price shocks caused by geopolitical factors. It describes impact scenarios of two conflicts: Russia’s invasion on Ukraine and the conflict in the Persian Gulf leading to the closure of the Strait of Hormuz. While UGS is essential for the short-term management of natural gas supply flows, its long-term value lies in providing a “strategic buffer” that allows energy systems to adapt to unforeseen geopolitical conflicts. Integrated storage management is indispensable for maintaining the operational integrity of the European transmission and energy system during periods of heightened instability. The paper also identifies necessary directions for the development of UGS systems. Between 2016 and Q1 2026, the share of eastern gas imports declined from over 40% to 5.2%, while LNG increased to 41.7% of total inflows, confirming the strategic importance of underground gas storage in maintaining energy system resilience. Full article

Diamond has emerged as a promising ultrawide-bandgap semiconductor material for next-generation electronics because of its unique combination of a wide bandgap, high critical electric field, superior carrier transport properties, exceptionally high thermal conductivity, and strong chemical and radiation stability. Over the past two decades, progress in crystal growth, substrate engineering, surface control, dielectric integration, and device fabrication has advanced diamond electronics beyond early proof-of-concept demonstrations. The review connects material properties, growth, doping, defects, and figures of merit with reported performance in hydrogen-terminated field-effect transistors, MOSFETs, Schottky and p–i–n diodes, and related power-device architectures. Emerging opportunities in ultraviolet photodetectors, multifunctional electronics, and memory-oriented diamond devices are also briefly considered. Among the device classes reviewed, diamond diodes currently show the strongest evidence of high-voltage capability, whereas transistor development remains constrained by threshold-voltage control, normally off operation, contact resistance, interface stability, and reliability. Diamond is therefore more likely to complement than replace established SiC and GaN technologies, particularly in specialized high-field, high-temperature, radiation-rich, and chemically demanding applications. Broader deployment will require scalable low-defect wafers, reliable n-type doping, stable interfaces and contacts, and more cost-effective manufacturing. Full article

The large-scale integration of photovoltaic generation into distribution grids has introduced significant operational challenges, including voltage excursions, reverse power flows, and increased variability. Battery energy storage systems (BESSs) offer a versatile solution by providing coordinated active- and reactive-power support. However, their scheduling in active distribution networks is challenging because of the non-convex alternating-current (AC) power-flow equations, the nondifferentiability of battery-degradation modeling, and uncertainty in renewable generation and demand. This paper proposes a two-stage methodology for the day-ahead operation of BESSs in ADNs. In the first stage, parallel particle swarm optimization (PPSO) determines the hourly active- and reactive-power schedules of the BESS units. In the second stage, a matrix-based multi-period AC power flow based on successive approximations evaluates the schedules and verifies voltage, thermal, converter-capability, and state-of-charge (SoC) constraints. A rainflow-counting degradation model is incorporated into the objective function to account for cycling and calendar aging costs. The methodology is assessed through ablation analyses comparing active-power-only and coordinated P–Q dispatches, degradation-unaware and degradation-aware scheduling, and serial and parallel PSO implementations. It is validated on modified 33-, 69-, and 136-node systems under deterministic and uncertainty-based operating conditions, including 100 demand and PV-generation scenarios. PPSO is compared with parallel versions of the adaptive Jaya algorithm (AJAYA), genetic algorithm (GA), multi-verse optimizer (MVO), salp swarm algorithm (SSA), grey wolf optimizer (GWO), and vortex search algorithm (VSA), using operating-cost reduction, computational time, solution variability, feasibility indicators, BESS lifetime, and weekly cost analysis. Additionally, exact one-sided Wilcoxon signed-rank tests with Holm adjustment are used to assess the statistical significance of the economic differences between PPSO and the benchmark methods. Results show that PPSO provides the lowest or most competitive operating costs and the shortest computational time in the evaluated cases, while all network and storage constraints remain satisfied. Full article