Search Results (2,397)

As a critical hydraulic component of pumped storage power stations, the side inlet/outlet directly affects unit efficiency, flow stability, and system safety. This study investigates the side inlet/outlet of a pumped storage power station using three-dimensional numerical simulations, focusing on the influence of the diffuser length L on hydraulic performance, and further analyzes the underlying mechanisms of energy loss based on entropy production theory. The results indicate that, with increasing diffuser length L, the flow rates in individual channels gradually deviate from the design values, leading to an aggravated imbalance in flow distribution. In contrast, the velocity non-uniformity coefficient C_V at the trash rack decreases, accompanied by a pronounced attenuation of recirculation and local flow separation, resulting in a more uniform and stable flow field. Moreover, increasing L improves the streamwise velocity uniformity within each channel, while the extent and intensity of the top recirculation zone are reduced, suppressing local flow separation. Quantitative analysis shows that when L increases from 65 m to 85 m, the total turbulent dissipation entropy production rate in the diffuser section increases linearly from 2732.32 W/K to 2842.32 W/K, whereas the direct dissipation entropy production rate increases from 0.41 W/K to 0.59 W/K. This indicates that turbulent dissipation entropy production plays a dominant role in the overall energy loss. Shorter diffusers tend to induce high-intensity local dissipation, whereas longer diffusers reduce local peak dissipation but increase the overall entropy production within the diffuser, reflecting a trade-off between local optimization and global energy loss. This study reveals the sensitivity and governing effects of diffuser length on the hydraulic characteristics of side inlet/outlets, providing a reference for geometry optimization and engineering design of similar hydraulic components. Full article

The increasing frequency of torrential rainfall due to global warming has resulted in a significant rise in urban flooding and river overflows. Rainwater pumping stations, typically located near rivers, serve as buffers between sewer systems and receiving water bodies, helping to mitigate flood risks. A primary challenge in operating these stations is optimizing pump performance to prevent flooding while minimizing energy consumption and costs. Various computational methods, including meta-heuristics and deep learning, have been proposed to tackle this optimization problem. However, most studies either overlook or inadequately address pump maintenance costs, which are essential for long-term operational efficiency. This gap stems from the lack of a comprehensive model that accurately captures the full spectrum of costs involved in pump operation. This paper introduces a cost estimation model that integrates both deterministic and probabilistic elements to enhance the energy-efficient operation of rainwater pumping stations. The model focuses on pumps with capacities of 100 m³/min and 170 m³/min, which are commonly used. It takes into account electricity consumption costs as well as maintenance costs arising from frequent on/off cycles and dry-run events. Predictions of failures due to these operational stresses are modeled using the Crow–AMSAA non-homogeneous Poisson process (NHPP) and Weibull distributions—probabilistic models widely used in mechanical failure analysis. To evaluate the proposed model, simulations were conducted using the Storm Water Management Model (SWMM), comparing a deep reinforcement learning-based control strategy with the current operational method at the Gasan Pumping Station in Seoul, South Korea. The pump operating costs associated with each method were calculated and analyzed using the proposed model, demonstrating its potential for ensuring cost-effective and reliable pump operation. Full article

We investigate the optical response properties of an atom-assisted spinning optomechanical system, in which a spinning optical resonator is coupled simultaneously to a two-level atomic ensemble and a mechanical resonator driven by a weak pump field. Remarkably, we demonstrate that by simply reversing the rotation direction, the system can be switched between a low-absorption electromagnetic and optomechanically induced transparency state and a high-absorption state, constituting a form of non-reciprocal optical control at the quantum level. Furthermore, by tuning the phase difference between the mechanical pump and the probe field, direction-dependent switching between absorption and gain is achieved. These non-reciprocal effects originate from the Sagnac-induced frequency shift in the optical mode, which leads to distinct optomechanical and atom–cavity couplings for opposite spinning directions. We also show that the absorption spectrum can be modulated by the angular velocity and the atomic number. Our results indicate that the optical properties of the hybrid system can be manipulated via the angular velocity, phase difference, and atom number, with potential applications in chiral photonic communications. Full article

Tropical cyclones kill thousands and inflict vast destruction annually. While ocean temperatures and atmospheric conditions dominate their formation and behaviour, forests’ potential influence has received little systematic attention. This review examines whether and how forests may affect tropical cyclone frequency, intensity, and behaviour. Support varies by mechanism and stage. Post-landfall effects have the strongest support: forests slow storms, moderate wind speeds and curb flooding through enhanced soil infiltration. Forests also influence storm tracks, though magnitudes are uncertain. Pre-landfall effects are less certain. These include processes that modify offshore humidity, temperature, and aerosols. The Biotic Pump theory proposes that forest cover creates pressure gradients drawing moisture inland, reducing its availability for ocean storms. Forest influences are likely to be most evident near thresholds for storm formation or intensification, where small perturbations in conditions can alter outcomes. This context-dependency reconciles divergent findings and aids the integration of forests into climate risk assessments. Forest conservation provides clear post-landfall protection; pre-landfall effects, while uncertain, further strengthen the case for protection and highlight research priorities. Full article

Background/Objectives: Hydrazones are organic compounds with the general structure R₂C=NNHR₁, distinguished by their versatility and modifiability, and are widely used in various applications due to their physicochemical and biological properties. They exhibit anticancer, anti-inflammatory, antibiofilm, and antibacterial activities. Antibiotic-resistant bacteria pose a serious public health threat, employing mechanisms such as enzymatic inactivation and efflux pumps. This study evaluated the antibacterial activity of the hydrazone HDZH1,4BENZ, a hydralazine-derived compound, as well as its potential adjuvant effect in combination with antibiotics against Staphylococcus aureus strains expressing efflux pumps. Methods: The strains used were 1199B (NorA efflux pump-expressing) and K2068 (MepA efflux pump-expressing). All assays were conducted using the broth microdilution method in Brain Heart Infusion (BHI) medium. Initially, the intrinsic antibacterial activity of the compound was determined. Subsequently, modulation assays were performed to evaluate its potential effect on efflux pump activity, with a standard efflux pump inhibitor included as a positive control. Results: Although HDZH1,4BENZ did not demonstrate significant direct antibacterial activity, the results indicate that this hydrazone exerts a notable inhibitory effect on the NorA (Norfloxacin resistance efflux pump A) and MepA (Multidrug efflux protein A) efflux pumps in S. aureus, thereby enhancing the efficacy of antibacterial agents. Conclusions: The activity of the hydrazone was comparable to that of chlorpromazine, suggesting that it may represent a promising alternative in the fight against antibiotic-resistant bacterial infections. Full article

Maintaining ballast performance in seasonal frozen regions is essential for resilient and sustainable railway infrastructure because freeze–thaw-driven fouling can shorten service life and increase maintenance-related material consumption. To investigate the deterioration mechanisms of fouled railway ballast in seasonal frozen regions, freeze–thaw cycle tests and cyclic loading model tests were conducted in sequence using a custom low-temperature geotechnical system. The test results processed by Origin software indicate that unfrozen water migrates toward the freezing front under temperature gradients and forms ice lenses during freezing. During thawing, meltwater is retained above the underlying frozen soil. Repeated freeze–thaw cycles therefore promote progressive water accumulation in the upper soil layers, eventually forming a clay layer with high water content. Under cyclic loading, interlayer thickening exhibited clear moisture thresholds relative to the clay liquid limit (LL = 24%). Below the LL (18–24%), ballast penetration and fines migration were limited and thickness increased slowly. Above the LL, rapid strength loss accelerated penetration and upward transport. At an initial water content of 32%, fines migration surpassed the ballast surface and the ballast became fully fouled, meaning that the fouled interlayer thickness equaled the full 100 mm ballast-layer thickness. Fouling severity increased sharply with moisture: the void contaminant index exceeded the maintenance criterion (VCI > 40%) at 28% water content and evolved into severe mud pumping at higher concentrations. Excess pore water pressure developed stratification with depth, maintaining an upward hydraulic gradient near the interface and yielding a net water loss of 2.24–6.91% in the upper fine-grained layer. These quantified thresholds and mechanistic insights provide actionable trigger points for condition-based maintenance and climate-adaptive design, helping extend track-bed service life and reduce resource-intensive ballast renewal in seasonal frozen regions. Full article

Deepwater drilling operations face critical challenges including narrow pore-fracture pressure windows, wellbore instability, and environmental concerns from drilling discharge. This paper presents a comprehensive systematic review of Riserless Mud Recovery (RMR) technology, tracing its evolution from its conceptual origins to its current applications, critically analyzing its technical limitations, and identifying future research directions. A systematic literature review was conducted covering peer-reviewed journals, SPE/IADC conference proceedings, industry technical reports, and independent academic studies from 1990 to 2025. Databases searched included Web of Science, Scopus, OnePetro, and Google Scholar, supplemented by Derwent Innovation Index for patents. After screening over 100 publications, approximately 60 references were selected following a two-step process excluding vendor-only promotional materials. Key findings reveal the following: (1) RMR technology has evolved through three distinct hardware generations—flexible hose systems, steel-pipe return lines with tandem pumps enabling deepwater breakthrough to 1419 m, and hybrid riser configurations for conceptual designs beyond 3000 m; (2) documented field benefits include 70% drilling fluid reduction, 9 days’ time savings per well, and successful mitigation of shallow geohazards across more than 1000 global well applications; (3) integration with casing-while-drilling and managed pressure cementing has enabled record-breaking performance of 1710 m in a single run; (4) independent academic validation confirms fatigue mechanisms affecting mud return lines; (5) systematic failure mode analysis identifies critical reliability issues in suction hoses, seals, and control systems; (6) quantitative economic analysis shows RMR cost-effectiveness depends on water depth, geological conditions, and environmental regulations. RMR technology has matured into a reliable drilling solution, yet its continued evolution requires addressing hardware limitations, developing dedicated well-control protocols, expanding to ultra-deepwater and emerging applications, and integrating digitalization for real-time optimization. Full article

Multi-regional electricity markets increasingly struggle to balance data privacy requirements with the computational burden of centralized clearing. To address this issue, this study proposes a distributed joint-clearing framework based on the Alternating Direction Method of Multipliers (ADMM) to co-optimize pumped storage hydropower (PSH) and battery energy storage systems (BESS) across energy, frequency regulation, and reserve markets. A mixed-integer programming model is formulated to maximize social welfare, explicitly capturing the time-coupled, energy-oriented characteristics of PSH and the fast-response, power-oriented capabilities of BESS. The global problem is decomposed into regional subproblems that can be solved in parallel. An adaptive penalty parameter strategy is further introduced to dynamically balance primal and dual residuals, thereby improving convergence and robustness in the mixed-integer setting. To address the limited economic interpretability of dual variables in mixed-integer programming (MIP) models, an approximate marginal pricing mechanism based on subproblem sensitivity analysis is proposed. A two-region, 24 h case study shows that the proposed method converges in around 65 iterations and achieves a social welfare outcome within 0.61% of the centralized optimum. By minimizing information exchange, the framework offers a scalable and privacy-aware solution for future multi-regional market operations involving heterogeneous energy storage resources. Full article

This review deals with the development and progress of micro-electromechanical systems (MEMS) actuators, which are needed in microfluidic applications, such as lab-on-a-chip and diagnostics. In the last 10 years, there have been tremendous advances in materials, microfabrication and computational modeling that have increased the functionality and scope of MEMS-based microfluidic actuation. This study classifies MEMS actuators on the basis of the physical method of actuation, including electrostatic, piezoelectric, and pneumatic actuation designs, in comparison with their application in pumping, valving, and droplet control. It examines the suitability of emerging structural and functional materials, such as piezoelectric thin-films and electroactive polymers, paying special attention to their reliability and biocompatibility. It also highlights the progress in multiphysics modeling that incorporates electrical, thermal, mechanical, and fluidic models, which facilitates the efficient design and performance optimization procedures. Other trends are multifunctional actuators with built-in sensing capability and the use of artificial intelligence (AI)-assisted design in production. With these developments, however, there exist issues of power efficiency, thermal control, fabrication uniformity and operational durability, and also the absence of standardized benchmarking. Finally, future research directions are outlined, including hybrid MEMS actuation, intelligent microfluidic operations, to improve the performance of the system and enable the transfer of the lab demonstrations to the large scale application of the system. Full article

Electrochemical machining (ECM) offers precise shaping by material dissolution with negligible mechanical or thermal impact on the workpiece. Metal parts with three-dimensional shapes, such as freeform surfaces or additively manufactured parts, can be addressed by robots with up to six degrees of freedom without significant mechanical impacts on the end-effectors and robots. This study summarizes the state-of-the-art of the use of robots in ECM by assessing the relevant literature. Several investigations were found that implemented or conceptualized the use of robotic arms in ECM sinking, jet-ECM or wire ECM, mainly for effective utilization of the processes. This study includes results of pure ECM, as well as hybrid ECM processes and the use of robots considering their accuracy, degrees of freedom and their application potential. Special emphasis is given to the role of robots in improving machining accessibility and their usability for valuable components in the aerospace, biomedical, and tooling industries. Furthermore, the review provides insights into electrolyte delivery mechanisms and pump configurations that facilitate efficient process performance. Overall, the utilization of robots in ECM not only enhances the process flexibility and surface quality but also aligns well with the aim of intelligent, automated, and high-precision manufacturing. Full article

This review synthesizes recent progress in modern energy storage technologies and proposes a selection-oriented comparison for power-system stabilization. Technologies are grouped into electrochemical, mechanical, chemical, and thermal storage, and evaluated using harmonized criteria (power and energy capability, response time, round-trip efficiency, lifetime, cost proxies, and maturity level). A comparative dataset and use-case mapping are used to link technology characteristics to grid services, with emphasis on voltage support, operational durability, and waste-heat utilization. The analysis highlights pumped-storage hydropower as the most robust option for long-duration, high-capacity applications, while battery energy storage systems are best suited for fast ancillary services, provided that cycle life, safety, and system integration constraints are met. Finally, the review discusses current technology trends (e.g., LFP and sodium-ion deployment, solid-state development, and commercialization barriers for lithium-sulfur) and identifies evidence-based directions for future research and deployment. Full article

With rapid economic development in China’s coastal regions, more oil stations are being built on soft soil foundations, facing risks such as foundation settlement and pipeline failures. Mechanical vibrations of oil pumps can induce resonance in pipelines, leading to rupture, leakage, and fire or explosion, threatening both safety and sustainable operation. Traditional monitoring methods, relying on physical models or data-driven approaches alone, are limited in capturing these coupled risks. This study proposes an ABC-XGBoost hybrid risk warning model, where the artificial bee colony algorithm optimizes XGBoost hyperparameters (iteration number, tree depth, learning rate) to improve predictive accuracy. By using multidimensional data—such as internal pressure, vibration amplitude, and ground settlement—the model evaluates stress and resonance risks in real time, supporting sustainable safety management. Validation with real station data shows an accuracy of 95.22%, 2.61% higher than the unoptimized model, demonstrating effective early warning and contribution to sustainable pipeline operation. Full article

Subtropical forest ecosystems, especially evergreen broad-leaved forests in the East Asian monsoon region, are a crucial component of the global terrestrial carbon cycle and make a key contribution to the “missing carbon sequestration” in the Northern Hemisphere. This review systematically integrates recent research progress on the carbon pool patterns, aboveground-subsurface biogeochemical processes, and global change responses of subtropical forests, summarizing the potential mechanisms of their sustainable carbon sequestration capacity and identifying current cognitive bottlenecks. Studies have shown that subtropical mature forests have carbon sequestration potential that exceeds traditional theoretical expectations, but there are still significant shortcomings in terms of carbon stability in deep soil (>1 m), quantitative constraints on rhizosphere activating effects, and assessment of ecosystem resilience under extreme climate events. Furthermore, the nonlinear interactions between factors such as climate warming, precipitation changes, and nitrogen deposition may trigger a critical turning point in carbon sink functions, and the water-carbon-geological coupling processes in special habitats such as karst and mangrove forests are often underestimated. We further propose that future research should focus on developing coupled models of “plant–soil–microbe hydrology”, combining molecular and isotopic techniques to elucidate microbial carbon pump mechanisms and strengthening long-term in situ experiments under combined extreme events to provide scientific support for subtropical forest carbon sink management and prediction. Full article

Hydrodynamic cavitation (HC) is an efficient technique for biodiesel production. The main contribution of this study is the development of a modular reactor with a universal stainless steel joint, whose design facilitates the installation, replacement, and maintenance of the orifice plate by eliminating flanges and bolts during assembly. Using this reactor, the study evaluated the synergistic interaction between feed pressure and methanol:oil molar ratio in the transesterification of soybean oil, employing a 3² factorial design. The orifice plate was 3 mm thick and had 19 holes with a diameter of 1.0 mm, installed downstream of the pump. The process was carried out for 45 min, using NaOH at 1 wt% relative to the oil and at 60 ± 5 °C. Feed pressures of 1.72, 2.41, and 3.10 bar and methanol:oil molar ratios of 6:1, 8:1, and 10:1 were evaluated, reaching a maximum yield of 92.98% at 3.10 bar and 8:1. Analysis of variance (ANOVA) confirmed a significant interaction (p < 0.0001) and allowed a second-order polynomial model to be fitted (R² = 0.9981). In contrast, conventional mechanical agitation required 90 min to achieve 95% yield. The biodiesel produced met most American Society for Testing and Materials (ASTM) D6751 requirements, confirming the potential of HC as a viable alternative for intensifying biodiesel production. Full article

Antimicrobial resistance is a growing global health crisis, with projections estimating up to 10 million deaths annually and more than 130 million hospitalizations attributable to resistant infections. Resistance emerges through microbial adaptation to sustained antimicrobial pressure, resulting in genetic and phenotypic mechanisms such as target mutations, enzymatic drug inactivation, efflux pump activation, biofilm formation, and metabolic adaptation that drive the emergence of multidrug-resistant pathogens and limit effective therapy. This bibliometric review analyzes the MEDLINE-indexed articles to characterize patient health and age factors, resistance mechanisms, pathogen types, and therapeutic strategies associated with antimicrobial resistance. The findings demonstrate that antimicrobial resistance is disproportionately reported among adults and chemotherapy-treated patients, with transmitted resistance emerging as the dominant driver, emerging from antibiotic misuse or overuse. Despite extensive mechanistic knowledge, treatment remains largely focused on escalation to newer antibiotics, while combination and adjunctive therapies are less commonly reported. These results analyze 308,290 studies to identify patient-related contexts, resistance mechanisms, pathogens, and therapeutic strategies. Full article