ABSTRACT This study employs numerical simulations to analyze flame propagation characteristics in order to investigate the evolution and acceleration mechanisms of premixed hydrogen flames under continuous disturbance. The simulation adopts a pressure-based solver, integrating the SIMPLE algorithm with adaptive mesh refinement technology. Detailed combustion reaction data are used to demonstrate the characteristics of flame acceleration and their associated physical quantities. Simulation results indicate that shear deformation induces flame curling. This process, combined with the velocity gradient formed at the combustion boundary and the resulting enhancement of turbulent kinetic energy, subsequently triggers increased flame instability. Throughout this process, the flame surface area progressively expands. The distortion of the premixed flame induced by this disturbance corresponds to an increase in velocity. When the flame front couples with pressure, both the pressure magnitude and the rise rate increase, thereby enhancing the positive feedback effect between them and improving flame acceleration efficiency. This study clarifies the transition characteristics of premixed flame acceleration. The acceleration process evolves from initial reaction-driven to flow-driven, ultimately relying on the synergistic propagation via pressure superposition. This progression systematically reveals the underlying mechanism of hydrogen flame acceleration.

ABSTRACT This study presents a comprehensive computational investigation of hydrogen (H2)/diesel dual-fuel combustion strategies for heavy-duty compression-ignition (CI) engines, with a particular focus on clarifying the combustion physics and optimization potential of dual direct injection (DDI) relative to port fuel injection of H2 with diesel direct injection (PFI/DI). A systematic comparison under identical energy and operating conditions reveals that, although PFI/DI yields lower nitrogen oxides (NOx) emissions due to ultra-lean premixed combustion, it suffers from uncontrollably high maximum pressure rise rates (MPRR) driven by end-gas autoignition, severely limiting its applicability at high loads. In contrast, DDI enables diffusion-controlled combustion with improved mixture stratification, resulting in lower MPRR and higher indicated thermal efficiency (ITE), albeit with increased NOx formation caused by localized high-temperature regions. Building on this comparison, an extensive parametric investigation of the DDI mode is conducted to identify the dominant factors governing performance and emissions. The results demonstrate that intake boosting and compression ratio primarily enhance ITE through reductions in wall heat transfer and exhaust losses, respectively. Injector jet angle and piston bowl geometry are shown to critically control jet-flame-wall interactions, with an intermediate jet angle of 72.5° combined with a toroidal piston bowl yielding the highest ITE by minimizing wall heat losses. Furthermore, the study reveals that diesel pilot injection timing and quantity have a negligible influence once reliable ignition is established, confirming that the pilot fuel primarily serves as an ignition source rather than a combustion-phasing control mechanism. Excessive swirl, however, is found to deteriorate combustion stability by promoting premixed heat release and elevated MPRR. Overall, this work provides new physical insight into the combustion dynamics of H2/diesel DDI operation and identifies key design and operating parameters for achieving high efficiency while mitigating combustion instability, offering practical guidance for the development of next-generation hydrogen-fueled heavy-duty CI engines.

Abstract From the mid‐late 2000s through at least the mid‐2010s, dynamic sea level (DSL) along the U.S. Gulf Coast rose at a rate of ∼5–6 mm , almost twice the rate of global mean steric plus barystatic sea level rise. Previous statistical and numerical modeling studies have suggested a number of hypotheses for this enhanced rise. However, the contributions from various atmospheric and hydrologic forcings had not yet been quantified in a physical model. This study quantifies forcing contributions to DSL using adjoint sensitivities from the observationally‐constrained Estimating the Circulation and Climate of the Ocean (ECCO) state estimation framework. DSL reconstructions with air‐sea fluxes from the ECCO state estimate and JRA55‐do river discharge show that winds along the Gulf and U.S. Atlantic coasts generate ∼80%–90% of subannual and 55%–70% of interannual variability of Gulf Coast DSL, indicating the dominant influence of coastal Kelvin and topographic Rossby waves at these shorter timescales. In contrast, only 1.0–1.6 mm (20%–30%) of the 2006–2017 DSL rise is associated with winds along the coastal waveguide. The remainder of the 2006–2017 DSL rise is associated with winds and heat fluxes in the tropical Caribbean and Atlantic (2.0–2.2 mm ), and winds and heat/freshwater fluxes in the subtropical‐to‐subpolar North Atlantic (1.7–1.9 mm ). A decline in Mississippi river discharge during this same period produced a decrease in Gulf Coast DSL that was most impactful along the western Gulf Coast (−1.0 mm ), reducing the rapid rise slightly.

One of the most significant impacts of climate change is sea-level rise, which is increasingly threatening to the coastal setting, infrastructure, and socioeconomic systems. Since a change at the sea level is spatially non-uniform and highly modulated by local oceanographic and climatic events, local or regional-scale measurements are necessary—especially in semi-enclosed basins. This paper examines the long-term variability of sea levels throughout the Persian Gulf and illustrates a strong spatial variance of the trends over the past and the future. Using three decades of satellite-derived observations, regional sea-level trends were estimated from monthly sea-level anomaly (SLA) data, which were also used to generate future projections to 2100. The analysis shows that the rate of sea-level rise along the UAE–Oman stretch is 3.88 mm year−1 and that of the Strait of Hormuz is 5.23 mm year−1, with a mean of 4.44 mm year−1 in the basin. Statistical forecasts of sea-level change were projected by a statistical forecasting scheme with high predictive ability with the optimal configuration of an average of 0.0391 m, an RMSE of 0.0492 m, and an R2 of 0.80 when independent validation was conducted. It is estimated that by 2100, the average rise of the sea level in the Persian Gulf is about 0.30–0.40 m, and the peak rise in sea level is at the Strait of Hormuz. Since these projections are based on statistical extrapolation rather than physics-based climate models, they are interpreted within the uncertainty envelope defined by IPCC AR6 scenarios. This study presents a unique, regionally resolved viewpoint on sea-level rise that is relevant to coastal risk management and adaptation planning in semi-enclosed marine basins by connecting robust statistical performance with physically interpretable regional patterns.

ABSTRACT To evaluate the effect of copper foam on the explosion safety of methane-hydrogen mixtures, this study investigated the influence of its location and hydrogen volume fraction on explosion characteristics with multiple obstacles, analyzing key parameters like explosion impulse and deflagration index. Results show that the reticulated copper foam attenuates the Helmholtz oscillation of overpressure and alters the maximum overpressure peak. The deflagration index, pressure rise rate, and peak positive impulse at 50 cm, and 60 cm are consistently higher than those at 75 cm. Furthermore, copper foam at 75 cm effectively suppresses secondary positive impulse generation. Copper foam significantly influenced the later stages; jet, reflux, and swallowtail flames were observed. The explosion hazard is highest with copper foam installed at 50 cm, followed by 60 cm, and lowest at 75 cm. Moreover, increasing the hydrogen volume fraction (up to 30%) enhances the overpressure peak, impulse, and flame evolution rate, resulting in more severe explosion hazards. These findings provide a reference for flame arrester design and enhancing the safety of hydrocarbon fuel use.

Over the last decade, crams on transformer oil-based nanofluids has advanced rapidly. Compared to pure transformer oils, vegetable oil-based nanofluids may be considered the future insulation fluids since they offer a unique potential for improving breakdown strength and heat transmission efficiency. In this paper, nanofluids (NFs) were made by dispersing nanoparticles (NPs) into mustard oil as the base oil because of their superior electrical and thermal properties. To create nanofluids, two types of nanoparticles, insulating nanoparticles Al2O3 and SiO2, were chosen and suspended in mustard oil at varying concentrations of 0.15 g/L, 0.3 g/L and 0.5g/L. The breakdown strength of AC and DC in oil samples with and without nanoparticles was determined using IEC 60156 standard test with a gap of 2.5 mm and a voltage rise rate of 2.5 kV/s. Summarizes the experiment's findings for the Alumina and silica-based nanofluids and their concentrations. The enhancement in breakdown voltage was approximately 15.23%, increased by adding alumina 0.15g/L concentration. It was also observed that the improvement in breakdown voltage was about 11.51% by adding silica 0.5g/L concentration. The experimental results were compared to those from earlier studies, revealing that most of the test results obtained in this study were comparable to those obtained in previous studies.

We study water uptake in plants by modelling the xylem as a narrow capillary tube through which sap rises under transpiration pull. We modify the classical Bosanquet equation, incorporating the effect of friction f, arising from xylem wall protrusions, while including corrections to the surface tension due to the presence of ions in the sap and due to local curvature via the Tolman correction. We also take into consideration an externally imposed transpiration flux. We identify a dimensionless tuning parameter, , that is a relative measure of capillary to hydrostatic forces that, along with f, affects system behaviour. In the absence of transpiration, transitions between oscillatory and non-oscillatory behavior of the sap column depends on , while its rate of rise depends on f. We find that the addition of transpiration to the xylem capillary system, by considering diffusion and evaporation at the leaves, causes the system to instead stabilize around a nonlinear center, also crucially increasing the maximal height to which the water rises. We obtain scaling power-laws for the time required for the sap to reach to reach its maximum height, and the characteristic time scale for oscillations in the column to decay to its fixed point, as functions, respectively, of f and of . We investigate the competitive effects of transpiration pull and presence of corrugation in the conduits. Our approach integrates capillary flow physics with dynamical systems theory to uncover new insights and get a more comprehensive and novel understanding of the problem of water transport in plants.

Abstract Accelerating sea level rise and increasing frequency of storms are impacting coastal wetlands. Similar to salt marshes, coastal freshwater wetlands provide important flood protection and storm abatement services, but their capacity to keep up with sea level rise and associated saltwater intrusion remains unclear. Long-term monitoring of wetland soil surface elevation using surface elevation table and marker horizons (SET-MH) has been conducted in salt marshes, while forested wetlands have not received as much attention. In 2015, we installed 18 SET-MHs in one restored and two mature forested wetlands on the coastal plain of North Carolina, all of which have experienced saltwater intrusion in recent years. We hypothesized that the restored wetland would have higher surface elevation gains, and areas protected from saltwater intrusion within all three sites would also have higher surface elevation gains. From 2016 to 2022 we measured surface elevation change and used marker horizons to measure vertical accretion. Rates of surface elevation change ranged from -4.25 to 4.79 mm/year, and vertical accretion rates ranged from -0.27 to 4.16 mm/year. All sites are vulnerable to future inundation, as even the highest rates of surface elevation gain were less than the observed 50-year rate of local sea level rise. Areas that experienced higher salinity exhibited higher rates of shallow subsidence. Our results support previous evidence that many coastal forested wetlands in the southeastern US are lagging behind sea level rise and, if elevation change rates do not accelerate substantially, they will experience ecological transformations in the coming decades.

Purpose While the irrigation and heating method has proven effective for monitoring cracks in underwater concrete structures, its localization accuracy is limited by the spacing of sensing-heating elements. This study aims to introduce an enhanced crack localization strategy that integrates a thin copper tube with a high-density fiber Bragg grating (FBG) array, thereby improving localization accuracy while maintaining monitoring efficiency. Design/methodology/approach A thin copper tube is embedded between the monitoring and irrigation tubes. A bare optical fiber with a sensing section of multiple fiber Bragg gratings (FBGs)at specific intervals is threaded through it. After coarse crack localization via the irrigation and heating method, the FBG section is moved near the crack. Hot water is then injected into the irrigation tube, forming a localized high-temperature zone around the crack, with efficient heat conduction via the copper tube. The precise crack location is determined based on the characteristic temperature response patterns at each FBG measurement point. Findings Experimental results under varying crack widths (0.3 mm and 0.8 mm) and water temperatures (45?°C, 55?°C and 65?°C) show that both heating rate and temperature rise amplitude follow a unimodal distribution centered at the crack. The proposed method achieves a localization accuracy of 10 mm (half the FBG spacing), with sensitivity improving as crack width and injected water temperature increase. Originality/value This paper presents a novel approach for precise crack localization using optical fibers and active thermal tracing. It innovatively combines a thin copper tube with a movable FBG array to address the final critical step missing in traditional irrigation and heating methods for underwater concrete structures. The study systematically examines temperature rise and heating rate distributions near cracks and their influencing factors. A novel two-stage monitoring strategy is proposed, starting with coarse screening via the irrigation and heating method, followed by precise localization using the proposed technique, significantly improving both accuracy and operational efficiency.

Navigating the unknown: Nature-based solutions for coastal climate adaptation under deep uncertainty.

Sources of organic carbon and environmental response characteristics in the mangrove region of Trat Province, Thailand, over the past 1,019 years.

The Investigation of Vitamin D and Menstrual Cycles Trial (the inVitD Trial): A clinical trial of vitamin D supplementation on the hypothalamic-pituitary-ovarian axis.

Seaward expansion of mangrove wetlands in the Dafeng Estuary, Beibu Gulf from 1988 to 2022.

Tidal dynamics and implications for coastal aquifer pollution vulnerability ranking.

The growing share of renewable energy sources in recent years has been driven by the development of national legislation in various countries aiming to reduce carbon dioxide emissions originating from fossil fuels. Sustainable growth of national economies therefore requires the search for novel green technologies. Biomass has recently been used as a supplementary fuel to coal. The literature describes the synergetic effect in the technical context of combustion in the power engineering sector. In the presented research, five types of biomass dust were added to coal dust. The selected explosion indices were determined using a 20 L sphere apparatus, in accordance with EN 14034 standards. The results demonstrate the impact of biomass on the course of dust–air explosions. A synergetic effect was observed and explained. Certain types of biomass were found to be characterized by a higher explosion pressure rise (15-17 % or 0.88-1.28 bar) and higher maximum explosion pressure rates (16-148 % or 57-143 bar/s) than those obtained for the samples tested separately. The results indicate that the implementation of biomass for co-combustion always requires a revision of the existing process safety measures designed for coal combustion.

An X-type rotary engine (XRE) that utilizes a High Efficiency Hybrid Cycle, combining high compression ratio with constant-volume combustion, could be considered an attractive option for both improved combustion efficiency and decreased emissions. However, research on optimizing its combustion in XREs is still limited. The optimization of ignition strategy can be beneficial for enhancing combustion performance and especially for reducing the unburned region due to the particular recess chamber. In this study, a three-dimensional CFD model of the XRE was developed and verified. A numerical study was conducted to analyze how ignition number, ignition location, and asynchronous ignition on combustion characteristics and energy losses of the XRE. Results showed that the twin-spark scenarios had a significantly higher flame propagation speed than the single-spark scenario due to the formation of larger flame fronts. The twin-spark plugs arranged along the rotor rotating direction (Case A1) had maximum peak pressure and indicated thermal efficiency, which increased by 19.6% and 9.8%, respectively, over the single-spark scenario. However, Case A1 produced higher NOx emissions and had the highest heat transfer losses, which boosted by 14% over the single-spark scenario. For this twin-spark arrangement, advancing the ignition of the leading-spark plug (L-plug) significantly reduced ignition delay and combustion duration, as well as boosted the pressure rise rate, peak pressure, and combustion efficiency at the price of a smaller increment of NOx and CO emissions. Notably, advancing the L-plug timing drastically decreased exhaust losses, but had only a minor impact on heat transfer losses. Thereby, it is recommended to set the L-plug timing in advance for practical engineering applications.

ABSTRACT This study aims to identify the re-explosion hazard after a primary explosion of a fuel-rich methane and bituminous coal powder mixture. Primary and re-explosion experiments were conducted using a spherical explosion testing apparatus. The results reveal that once the mixture of methane and bituminous coal powder reaches a certain degree of fuel enrichment, an explosion can occur under the condition of reintroducing a certain volume of air and igniting. However, the pressure rise rate and explosion pressure of re-explosions are both lower than those recorded in the primary explosion. Nonetheless, the residual gas re-explosion exhibits a maximum pressure exceeding 0.3 MPa, with the maximum rate of pressure rise surpassing 1.8 MPa/s. The residual gas mixture with explosibility significantly reduces the lower explosion limit of methane and increases the risk of re-explosion. The re-explosion characteristics exhibited significant variations with the changing re-added methane concentration after a primary explosion. The premixed laminar burning velocity and flame temperature followed consistent trends with the explosion characteristic parameters. Furthermore, the key elementary reactions governing the combustion kinetics were identified. The results provide new insights into the re-explosion phenomenon and provide data support for assessing the hazards of a re-explosion accident in coal mines.

Projected sediment supply deficits threaten intertidal wetland resilience to sea-level rise in southeast Australia.

Supercritical CO2 pipeline transportation is a crucial link in Carbon Capture, Utilization, and Storage (CCUS). Compared with traditional oil and gas pipelines, if a supercritical CO2 pipeline is shut down for an excessively long time, the phase state of CO2 may transform into a gas-liquid two-phase state. It is urgently necessary to conduct research on the phase change mechanism and safety control during the restart process of gas-liquid two-phase CO2 pipelines. Based on a certain planned supercritical carbon dioxide pipeline demonstration project, this paper proposes a new pipeline safety restart scheme that actively seeks the liquefaction of gaseous CO2 inside the pipeline by injecting liquid-phase CO2 at the initial station. Through numerical simulation and experimental methods, the co-variation laws of parameters such as temperature, pressure, density, and phase state during the pipeline restart process were revealed. It was found that the pipeline shutdown and restart process could be subdivided into four stages: shutdown stage, liquefaction stage, pressurization stage, and displacement stage. The phase transition line would form a closed curve that is approximately trapezoidal. It is suggested to optimize the restart scheme from aspects such as reducing the restart time, controlling the pressure rise rate, and saving CO2 consumption. It is proposed that the liquid holdup of CO2 fluid in the pipe at the initial moment of restart and the mass flow rate of CO2 injected at the initial station during the restart process are the main controlling factors affecting the evolution of the phase path of pipeline restart. For the demonstration project, the specific critical threshold values are given. The research results can provide a certain theoretical guidance and reference basis for the safe restart method of supercritical CO2 pipelines.

BackgroundValid cognitive screening tools are necessary as worldwide rates of dementia rise. Screening tools such as the Addenbrooke's Cognitive Examination‐III (ACE‐III) validated in several languages and countries, including India, are useful for identifying cognitive impairment in older adults. However, certain ACE‐III items may yield high error rates, even among cognitively normal individuals, especially when level of education is considered. This study assessed the performance of individual ACE‐III items in a cohort of cognitively normal older adults in India.MethodParticipants included 132 Malayalam‐speaking older adults (mean age: 66.8, SD=4.7; 61% male; mean education: 10.6, SD=3.1 years) from the Kerala Einstein Study, a community‐based longitudinal study of pre‐dementia syndromes in Kerala, India. Participants completed the Malayalam‐version of the ACE‐III, along with a comprehensive neuropsychological battery. Cognitive normality was established through a consensus diagnosis by a neuropsychologist and neurologist; of these individuals 70 were without cognitive complaint and 62 reported some cognitive complaint. Frequencies of full, partial, and no credit for individual ACE‐III items were analyzed. Education was dichotomized to higher (10+ years) versus lower (<10 years) and chi square analyses of individual ACE‐III items between these groups were evaluated.ResultCertain ACE‐III items were nearly universally credited (≥94%) in this cognitively normal cohort, including orientation, word repetition, sentence repetition, comprehension of instructions, picture identification, word reading, dot counting, and letter identification. However, other items revealed high rates of partial or no credit, with over 25% of participants struggling to achieve perfect scores on tasks such as clock drawing, cube copying, picture naming, serial 7s, and recalling a name and address. For many of these items, lower education was significantly associated with higher error rates.ConclusionWhile the ACE‐III is a robust and validated cognitive screening tool, certain items may have limited utility due to a high error rate among cognitively normal participants. This is particularly evident in Malayalam‐speaking Indian older adults with lower levels of education. These findings highlight that errors on specific ACE‐III items (as identified in this study) are relatively common in this population and should be interpreted cautiously to avoid mischaracterizing normal variations in performance as pathological.