Air Water Research Articles

Effects of pore water and pore air pressure on the slope failure mechanisms due to rainfall in centrifuge investigation

BackgroundThe slope failures triggered by heavy rainfall are challenging to predict. However, their severe impact and potential for extensive damage emphasize the urgent need for effective strategies to mitigate these risks. This study aimed to investigate the effects of pore water pressures (PWPs) and pore air pressures (PAPs) on slope failure during heavy rainfall under centrifuge condition. Three centrifuge rainfall model tests were conducted with varying rainfall intensities (I) and relative densities (Dr). In this experiment, the slope model was subjected to a centrifugal acceleration of 30 G.ResultsIn all cases, slope failures started at the slope toes when the PWPs became positive and phreatic surfaces appeared on the slope surface. In the Toyoura sand case, the PAPs increased slightly at the slope crest, hardly changed at the slope toe, and oscillated at the slope shoulder due to rainwater infiltration. The entire slope failure was observed in this case. In the Silica sand cases, only localized slope toe failures were observed. The PAPs slightly oscillated with small changes in the silica sand case with a relative density of Dr = 50%. However, in the case with a Dr = 25%, the PAPs at the slope toe significantly increased compared to the other parts, and the oscillations were comparatively large. After the first failure occurred at the slope toe in the silica sand case with a Dr = 25%, cracks and slip lines appeared at the slope crest.ConclusionsThe three cases illustrated the complex relationship between soil properties, rainfall intensity, and the dynamics of pore water and pore air pressure on slope stability during heavy rainfall. From the behaviour of PAPs and PWPs in all cases, it was found that the transition from air to water occurred smoothly, and the isolation of air was not observed even during heavy rainfall. Changes in PAPs were far smaller than those in PWPs, indicating a smaller impact on slope stability than PWPs.

Design and Improvement of Tandem Twin-Rotor Aerial-Aquatic Vehicle Based on Numerical Analysis

To enhance the air–water adaptability of the aerial-aquatic vehicles (AAVs), an improved tandem twin-rotor AAV design is proposed based on the characteristics and application requirements of air–water cross-domain movement. Computational fluid dynamics (CFD) software was used to simulate the underwater cruising state and dynamic water entry process of the tandem twin-rotor AAV. Results indicate that the underwater cruise resistance of the improved tandem twin-rotor AAV is relatively small. Among them, the two sets of tandem air power systems account for a relatively large proportion of the underwater drag, about 29.8%, while the drag reduction achieved by improving the head shape is around 15.4%. The head shape, water entry angle and speed have a great influence on the water entry trajectory and attitude of the tandem twin-rotor AAV. Following improvement, the tandem twin-rotor AAV demonstrates an enhancement in reducing the deviation of the water entry trajectory, mitigating water surface ricochet and enhancement of water entry depth to a certain extent. The inclination angle should be in the range of 20–30∘ to alleviate unfavorable outcomes, including prolonged water entry time caused by water surface ricochet at lower entry angles, while concurrently mitigating the heightened impact pressure resulting from steeper entry angles. Higher entry velocities lead to greater impact pressures, necessitating careful consideration of water entry depth and impact pressure to prevent adverse effects on structural integrity.

Numerical and Experimental Study on the Hydrodynamic Performance of a Sloping OWC Wave Energy Converter Device Integrated into Breakwater

This study presents numerical and experimental investigations on an oscillating water column (OWC) wave energy device integrated into a sloping breakwater. Regular waves were generated in a physical wave tank to investigate the hydrodynamic performance and extraction efficiency of the small-scale nested OWC device. Simultaneously, to complement various scenarios, numerical simulations were conducted using the open-source computational fluid dynamics platform OpenFOAM. The volume of fluid (VOF) method was employed to capture the complex evolution of the air–water interface, and an artificial source term (Forchheimer flow region) was introduced into the Navier–Stokes equations to replace the power take-off (PTO) system. By analyzing wave reflection properties, energy absorption efficiency, and wave run-up, the hydrodynamic characteristics of the inclined OWC device were explored. The comparison between the numerical and experimental results indicate a good consistence. A smaller front wall draft broadens the high-efficiency frequency bandwidth. For relatively long waves, increasing the air chamber width enhances energy conversion efficiency and reduces wave run-up. The optimal configuration was achieved with the following dimensionless parameters: front wall draft a/h=1/3, air chamber width d1/h=2/9, and slope i=2. Due to the sloped structure, when compared with a vertical OWC, long waves can more easily enter the chamber. This causes the efficient frequency bandwidth to shift towards the low frequency range, allowing more wave energy to be converted into pneumatic energy. As a result, wave run-up is reduced, enhancing the protective function of the breakwater.

The Corrosion Behavior of Carbon Steel Materials Used at Nuclear Power Plants During Deactivation and Decommissioning Processes

This study is focused on the corrosion behavior of carbon steel A106 B in a static water environment, which simulated the decommissioning transition phase of BWR power plants. When the autoclave was filled with stagnant water, the corrosion rates of carbon steel pipe for the cold-drawn and hot-rolled samples were 23 μm/year and 19 μm/year, respectively. When the autoclave was not completely filled with water, leaving the samples fully submerged, the corrosion rate for the hot-rolled sample increased to 88 μm/year. In an autoclave with periodic water flow, the corrosion rate for the cold-drawn sample decreased to 11 μm/year. When the autoclave was not completely filled with water, the sample positioned at the air–water interface exhibited the highest corrosion rate of approximately 102 μm/year. These results indicate that the influence of ion concentration on the corrosion rate outweighed that of dissolved oxygen. Sufficient oxygen concentration facilitated the formation of FeOOH or Fe2O3, while an oxygen-deficient environment favored the formation of Fe3O4.

Assessing Experts' Perspectives on Challenges and Health Priorities Based on One Health Framework in Yazd Province

This study employed One Health Framework to identify and prioritize health challenges in Yazd Province, Iran. By combining qualitative and quantitative methods, the research explored various factors influencing health outcomes, including access to healthcare, quality of services, disease prevalence, and social determinants of health. Key findings revealed that water scarcity, cancer, cardiovascular diseases, air pollution, and nutritional support for vulnerable groups were the most pressing health issues. The One Health approach offers a comprehensive strategy to address these challenges by integrating human, animal, and environmental health. By fostering intersectoral collaboration and promoting interdisciplinary education, policymakers can implement effective interventions to improve public health in Yazd Province and beyond. The study's findings can serve as a valuable resource for developing evidence-based health policies and programs.

Numerical Simulation of Wave-Induced Scour in Front of Vertical and Inclined Breakwaters

The erosion of the seabed in front of shoreline structures due to wave action is a critical concern. While previous models accurately depict fluid and sediment interactions, they each have limitations and require significant computational resources, especially when simulating complex processes. This study proposed and validated a numerical model for simulating wave-induced sediment transport by integrating three key components: (1) a main solver based on large eddy simulation that includes the porosity of permeable materials, (2) a volume of fluid module to track the air–water surface, and (3) a sediment transport module that includes both bedload and suspended load to compute sediment concentrations and seabed changes. The model was validated against previously published experimental data, demonstrating its accuracy in capturing both wave motion and seabed profile changes induced by sediment transport. Furthermore, the numerical model was applied to study the effects of varying breakwater slopes on sediment seabed profile changes. The results show that steeper breaker slopes led to more concentrated wave energy near the structure, resulting in deeper scouring and higher sediment displacement. These results indicate that the proposed model is a valuable tool for coastal engineering applications, particularly for designing breakwaters, to mitigate sediment erosion and improve sediment stability.

Is it Possible to Detect a Rotating Spherical Colloidal Particle?

A single micrometer‐size spherical colloid has been set in rotation by transfer of light orbital angular momentum. This particle is floating at an air–water interface. Steady‐state rotational frequencies of the order of one hertz have been observed, depending on the topological charge of the beam and on its power, in agreement with expected values. The detection is performed using the rotational Doppler shift of the diffused light. Two time constants have been evidenced in the rotational velocity dynamics. The first one is related to the friction of the colloid with the fluid (air and water), whereas the other one is principally associated with the wall friction of the air–liquid interface with the container. This measurement technique makes it possible to identify dynamic parameters of the rotational movement of any spherical object, which is usually impossible to detect.

Covalent Organic Frameworks for Boosting H2O2 Photosynthesis via the Synergy of Multiple Charge Transfer Channels and Polarized Field

AbstractCovalent organic frameworks (COFs) serve as one of the most promising candidates for hydrogen peroxide (H2O2) photosynthesis, while attaining high‐performance COFs remains a formidable challenge due to the insufficient separation of photogenerated charges. Here, through the rational design of bicarbazole‐based COFs (Cz‐COFs), we showcase the first achievement in piezo‐photocatalytic synthesis of H2O2 using COFs. Noteworthily, the ethenyl group‐modified Cz‐COFs (COF‐DH‐Eth) demonstrates a record‐high yield of H2O2 (9212 μmol g−1 h−1) from air and pure water through piezo‐photocatalysis, which is ca. 2.5 times higher than that of pristine Cz‐COFs without ethenyl groups (COF‐DH‐H) under identical condition and COF‐DH‐Eth without ultrasonic treatment. The H2O2 production rate originates from the synergistic effect between an ultrasonication‐induced polarized electric field and the spatially separated multiple charge transfer channels, which significantly promote the utilization of photogenerated electrons by directional transfer from bicarbazole groups to the ethenyl group‐modified benzene rings. Several Cz‐COFs and bifluorenylidene‐based COFs (COF‐BFTB‐H) with similar twisted monomers exhibit obvious piezoelectric performance for promoting H2O2 generation, signifying that organic ligands with a twistable structure play a crucial role in creating broken symmetry structures, thereby establishing piezoelectric properties in COFs.

Patterns and Relationships of Pesticide Use in Agricultural Crops of Latin America: Review and Analysis of Statistical Data

The excessive use of pesticides in agriculture causes problems related to public health; biodiversity; the contamination of water bodies, soil and air; and general environmental degradation, including interactions with climate change effects. The aim of this work was to describe the patterns of pesticide use in 17 Latin American countries and their associations with the total harvested area and the harvested areas of the five main crops on the basis of statistics reported by the Food and Agriculture Organization from 1990 to 2021. Principal component analysis (PCA) revealed four different patterns among countries according to the magnitude of pesticide application: Brazil (G1) > Argentina (G2) > Colombia and Mexico (G3) > Central and South America (G4). Together, more than 1.2 million tons of active ingredients is applied annually, carrying harmful effects and risks. In the joint analysis of both datasets (applied pesticides and harvested area), different correlations were observed between the amount of pesticides applied and the harvested area; for example, in G1 and G2, positive and significant correlations were detected between the applied amounts of total pesticides, herbicides, insecticides and bactericides and the total area harvested by the main crop, but in G3, there was a negative correlation with the five main crops.

Effect of pre-deformation on corrosion fatigue crack growth of Type 316NG steel in 325 °C deaerated water

Abstract The pre-deformed 316NG (00Cr17Ni12Mo2N) was prepared by cold rolling at room temperature and hot rolling at 400°C. The effect of pre-deformation on fatigue crack growth both in 325 °C deaerated water and room temperature air was investigated. The effect of pre-deformation on corrosion fatigue crack growth (CFCG) in 325 °C deaerated water was much smaller than that on fatigue crack growth (FCG). The cold rolling significantly enhanced CFCG rates while the applied Δ K closed to 11 MPa•m1/2 or the applied loading frequency decreased to 0.1Hz. The accelerating effect of hot rolling on CFCG tended to get evident until the pre-deformation increased to 30%. Dynamic recovery was observed near the corrosion fatigue crack tip in hot rolled 316NG, which may result in relatively low CFCG rates.

Carbon dioxide exchange across water–air interface and its influencing factors in middle reaches of Yellow River during winter

ABSTRACT River systems strongly contribute to CO2 emissions. However, despite numerous reports on gas emissions from ice, the current understanding of CO2 exchange of rivers in winter and the factors affecting it is still relatively limited. To shed light on CO2 exchange and the factors influencing it for rivers during winter. Based on intensive field measurements using floating chambers, riverine CO2 exchange in middle reaches of Yellow River in China was examined. Our results showed net emissions of CO2 across the ice-free interface (51.874∼162.478 mg/m²·h). Compared with other rivers worldwide, the CO2 exchange is higher than most major rivers, such as the Lena and Kolyma Rivers. However, at the ice-covered river monitoring site, CO2 exchange across the water–air interface exhibited a net uptake, ranging from −36.336 to 0 mg/m²·h. Furthermore, the relationships between CO2 exchange and relevant physicochemical variables showed that CO2 emissions negatively correlated with pH and ice thickness and positively correlated with water velocity, wind speed, water temperature, atmospheric temperature, ammonia nitrogen levels, and total phosphorous content. This study is scientifically valuable as the findings provide insight into the CO2 exchange pattern that occurs at the water–air interface of rivers during winter both ice-covered and ice-free sites.

Water droplet evaporation in air: Effects of interfacial thermal and mass diffusion resistance

Evaporation of water droplets in air is a process highly relevant to a variety of environmental, industrial, and biomedical applications. In conventional hydrodynamic modeling of droplet evaporation, it is usually assumed that thermodynamic equilibrium exists at the water-air interface. However, such an assumption could result in considerable errors in predicting the evaporation rate of micro/nanoscale water droplets in air. In this work, we use the combination of kinetic theory-based model and hydrodynamic model to study the effects of interfacial resistance on the evaporation behavior of water droplets in air. The interfacial thermal resistance and interfacial mass diffusion resistance predicted by the kinetic theory-based model are first validated by MD simulation results, and then incorporated into the hydrodynamic model to predict the influence of the water droplet size, air temperature, pressure and humidity on the water droplet evaporation rate and droplet temperature. The evaporation behavior of water droplets in air predicted by our kinetic-hydrodynamic model are corroborated by MD simulation results and the recent experimental data. Our modeling results show that, at normal temperature and pressure (i.e., 25 °C and 1 atm by NIST), the equivalent length of thermal resistance and mass diffusion resistance at water-air interface are both ∼200 nm. This indicates that, at normal temperature and pressure, the effects of interfacial thermal and mass diffusion resistance on evaporation of water droplets in air cannot be ignored if the droplet diameter is less than 20 μm. The thermodynamic equilibrium assumption is only valid if the droplet diameter is greater than 20 μm. Once the droplet size is greater than 100 μm, the radiation heat transfer and convection effects must also be taken into account to give a more accurate prediction of droplet evaporation rate.

Effects of Physical Cooling on the Temperature and Performance of Newly Laid Porous Asphalt Mixtures

Porous asphalt pavements need to be cured for 24 h~48 h before they can be opened to traffic. In an emergency, physical cooling methods, such as water sprinkling and air blowing, can be used to accelerate cooling, but the effects of the two methods on the mechanical properties and durability of porous asphalt mixtures are still unclear. In this research, firstly, the dropping and rising temperatures of the pavement surface during the water sprinkling process of newly laid porous asphalt mixtures in real projects were analyzed. The effects of the two conditions of water immersion and water sprinkling on the mechanical properties of porous asphalt mixtures were clarified, and water sprinkling technology for porous asphalt mixtures was proposed. Secondly, the effects of air blowing on the temperature reduction and strength loss of porous asphalt mixtures was analyzed, and the pavement surface temperature control standard that was suitable for air blowing was proposed. Finally, a seven-year observation was carried out on the water sprinkling cooling test section in the actual project. The research results show that water immersion or the sprinkling of water repeatedly during the curing period of porous asphalt pavements reduces the strength of the mixture. It is recommended to use a water amount of 0.3 kg/m2 once and sprinkling four times before painting road markings and two times after painting road markings; this was the best water sprinkling cooling process for porous asphalt pavements. The use of air blowing can accelerate the temperature reduction of porous asphalt mixtures, but the mechanical properties of the mixtures are attenuated after air blowing. Air blowing can be carried out when the pavement surface temperature is lower than 70 °C. Compared with the road section without water sprinkling for cooling, the use of the determined process to cool the newly laid porous asphalt mixtures by water sprinkling does not have a significant adverse effect on their durability. There is also no significant difference in the performances of the two road surfaces within a seven-year service. In an emergency, physical cooling methods, such as water sprinkling or air blowing, can be used to accelerate the temperature reduction of the newly laid porous asphalt mixtures, so as to achieve the purpose of quickly opening to traffic.

The Langmuir Monolayer as a Model Membrane System for Studying the Interactions of Poly(Butyl Cyanoacrylate) Nanoparticles with Phospholipids at the Air/Water Interface

Poly(butyl cyanoacrylate) (PBCA) nanoparticles have numerous applications, including drug and gene delivery, molecular imaging, and cancer therapy. To uncover the molecular mechanisms underlying their interactions with cell membranes, we utilized a Langmuir monolayer as a model membrane system. This approach enabled us to investigate the processes of penetration and reorganization of PBCA nanoparticles when deposited in a phospholipid monolayer subphase. Atomic force microscopy (AFM) was employed to visualize Langmuir–Blodgett (LB) films of these nanoparticles. Additionally, we examined the state of a monolayer of Pluronic F68, a stabilizer of PBCA nanoparticles in suspension, by measuring the changes in relative surface area and surface potential over time in the barostatic regime following PBCA suspension spreading. Based on these findings, we propose a molecular mechanism for nanoparticle reorganization at the air–water interface.

Hydrolytic instability of laser-ablatively deposited CaSi2 coatings in air and neutral water affects the behavior of bone healing-related cell types

Calcium silicide (CaSi2) instability in humid air or pH-neutral water remains unknown, although the topochemical formation of silicene from CaSi2 in various aqueous phases is a well-known process. Here we report on laser ablation of CaSi2 in the vacuum and ethanol, characterize coatings deposited on titanium substrates with electron microscopy, X-ray photoelectron, Raman, and infrared spectroscopy, and examine the instability of the deposited coatings in humid air and neutral water. We further investigate the behavior of human mesenchymal stromal cells (hMSCs), vascular cells (HUVECS, human umbilical vein endothelial cells), and macrophages (derived from THP-1 cell line) in contact with the deposited coatings submerged in cell culture medium. The observed results indicate that the CaSi2 coatings undergo topochemical conversion to silicene, which is accompanied by hydrolytic reactions leading to inorganic Ca compounds and SiO2, and that the response of all cell types in the hydrolyzed CaSi2 surface domain is negatively affected by the nature of the hydrolytic products. In contrast, cells showed a tendency for enhanced biocompatibility towards the CaSi2 particles ablated in the vacuum. The results suggest that coating approaches can significantly influence cell behavior outcomes.

Site selection for solar power plants using GIS and Fuzzy Analytic Hierarchy Process: Case study of the Western Mediterranean Region of Turkiye

As global warming becomes increasingly evident, the need to use renewable energy sources cannot be overstated. The consumption of fossil fuels in energy production not only exacerbates the effects of global warming but also negatively affects air quality and puts human health at serious risk. The objective of this research is to determine the most suitable locations for solar power plants (SPPs) in the Turkish provinces of Antalya, Burdur, and Isparta, which are situated in the Western Mediterranean Region (WMR). The study employs the Fuzzy Analytic Hierarchy Process (FAHP), a Multi-Criteria Decision Making (MCDM) method, in conjunction with Geographic Information Systems (GIS) for the extraction of spatial information. In evaluating SPP site selection, 11 criteria were considered, including climate, economy, topography, and environmental factors. To produce more objective results during the decision-making phase, a thorough analysis of the relationship between solar irradiance and climatic factors such as air temperature, cloud frequency, and water vapor density which are crucial for the power plant's efficiency in SPP projects was conducted using machine learning techniques. The criteria weights were calculated by the FAHP method, considering expert opinions, literature observations, and machine learning results. The results show that approximately 20% of the region is suitable for SPP.

3D printing of a multi-performative building envelope: Assessment of air permeability, water tightness, wind loads, and impact resistance

This study investigated the 3D printing feasibility of mono-material facade panels with recycled thermoplastic. The design had integrated performance parameters, namely air permeability, water tightness, resistance to wind loads, and impact resistance, and fabrication parameters in a computational iterative process to inform the geometry topology. The fabrication parameters were integrated and evaluated for geometry accuracy, print path accuracy of 5 mm length, overhang higher than 45°, inner layer adhesion, and adhesion to the print bed. Two panels, measuring 1.6-meter length and 2-meter height, and six connections were fabricated and evaluated in a standardized facade testing rig. The air permeability displayed a larger than 1.5 m3/m2·h permissible Class 1 value due to air gaps in the manufactured panels. The same gaps that occurred during the fabrication process permitted water flow in both panels after 7 minutes of testing. The panels passed standardized serviceability and safety standards for wind load resistance and achieved a maximum E5 class for impact resistance. The structural strength values were 1500 Pa for serviceability, 2250 Pa for safety load, and 3262 Pa for breaking load. These findings demonstrated that 3D-printed geometries have a high potential to facilitate sustainable design strategies by integrating multiple performances within a mono-material building envelope.

Diel temperature patterns unveiled: High-frequency monitoring and deep learning in lake Kasumigaura

The diel variation of water temperatures is crucial information for lakes. This study investigated such variation in Lake Kasumigaura, the second largest lake in Japan, situated 60 km from the Tokyo metropolitan area, utilizing high-frequency monitoring and deep learning techniques. Data from high-frequency monitoring of vertical water temperatures at seven depths were employed. A convolutional neural network (CNN) based deep learning model was developed and assessed across three input scenarios. The impact of forecast horizons ranging from one to 48 h ahead on model performance was examined. Results indicate a degradation in model performance with increasing forecast horizons, irrespective of input scenario or water depth. Notably, the CNN model demonstrates superior performance in near-term and medium-term forecasts compared to long-term predictions, underscoring the need for enhanced efforts in long-term forecasting. Overall, the CNN model effectively reproduces vertical water temperature profiles and captures diel variations in lake water temperatures. Incorporating additional input variables does not necessarily improve model performance; however, using surface water temperatures and air temperatures as inputs produces acceptable results for modeling vertical temperature profiles. These findings have implications for lake management in Lake Kasumigaura (e.g., controlling phytoplankton and zooplankton communities) and offer insights into water temperature modeling for other lakes.

Tropical Cyclone Intensity Prediction Using BP-RNN From GPS-Derived Precipitable Water Vapor and Surface Meteorological Data

Abstract Tropical cyclones frequently threaten tropical coastal areas, making accurate prediction vital. While cyclone track forecasting has improved, predicting cyclone intensity remains challenging. This study uses precipitable water vapor (PWV) and other surface meteorological data to predict wind intensity during tropical cyclone Seroja in southern Indonesia. Data from two GPS stations, CKUP and CRTE, near the cyclone’s path, were analyzed. We employed neural network (NN) algorithms to model nonlinear relationships between variables, utilizing backpropagation to minimize error. The NN was fed with time series data across various hour window sizes (0h, 6h, 9h, and 12h), under the assumption that current parameters influence future conditions. Independent variables included PWV, ZTD, partial pressure of water vapor, temperature, and air pressure, with additional attributes implemented in multiple scenarios. Two years of data (2019-2020) were used to train the model, and wind velocities were estimated during cyclone Seroja. At CKUP, scenario 1 with a 9h window size achieved a probability of detection (POD) of 89% and a critical success index (CSI) of 84%. At CRTE, scenario 4 with a 6h window size achieved a POD of 73% and a CSI of 55%. The root mean square error for predicted wind speed was 1.32 m/s at CKUP and 2.08 m/s at CRTE. This study demonstrates the potential of integrating GPS and meteorological data to enhance cyclone intensity prediction, especially in cyclone-prone regions like Indonesia, offering a valuable contribution to local and global disaster preparedness.

Dynamic analysis of the air–water interface instability in a wind-wave flume: Initial conditions for wave generation

This paper aims to investigate the dynamic mechanism for a previously calm water surface under a background wind field, which would lose stability due to minor perturbations. When spatial distribution and growth rate of the shear wind field satisfy a certain relationship, an Orr–Sommerfeld equation can be derived from linearized Navier–Stokes equations, for the amplitude of perturbation waves at the air–water interface. After transforming its coordinates to a finite interval, this fourth-order linear ordinary differential equation with variable coefficients can turn into a linear singular differential equation. It is solved under the background flow fields of air and water using the corrected Fourier method that we previously developed, to yield two sets of four analytical solutions with physical significance. The perturbation flow at the air–water interface must satisfy the kinematic and dynamic matching conditions (continuity of velocity and smooth transition of shear stress), which results in a fourth-order homogeneous linear algebraic equation for four undetermined constants. Setting various parameters in accordance with measured data with a wind-wave flume, the corresponding perturbation waves solution is identified. Our calculation densely distributes the most unstable and readily growing waves among perturbation waves with small phase speeds, consistent with the experimental results. Our perturbation solutions over a flat air–water interface are only applicable to the short period after instability onset, which provides an initial condition for wave generation. The consequent interaction between small-amplitude waves and wind field is beyond the scope of our linear theory, which has indeed been sufficiently addressed in the literature.