Thickness Of Water Layer Research Articles

Ocean response offshore of Taiwan to super typhoon Nepartak (2016) based on multiple satellite and buoy observations

Multi-satellite and buoy observation data were used to systematically analyze the ocean response offshore of Taiwan to Super Typhoon Nepartak in 2016. The satellite data showed that a high sea surface temperature combined with a thick warm water layer and deep mixed layer provided a good thermal environment for continuous intensification of the typhoon. Two high-resolution buoys (NTU1 and NTU2) moored 375 and 175 km offshore of southeastern Taiwan were used to clarify the typhoon–ocean interaction as the typhoon approached Taiwan. The ocean conditions were similar at the two buoys before the typhoon, and both buoys were on the left side of the typhoon track and suffered similar typhoon factors (e.g., typhoon intensity and translation speed) during its passage. However, the ocean response differed significantly at the two buoys. During the forced period, the entire upper ocean was cooled at NTU1. In contrast, there was a clear three-layer vertical structure at NTU2 consisting of cool surface and deep layers with a warmer layer between the two cool layers. These responses can be attributed to strong upwelling of a cold eddy at NTU1 and vertical mixing at NTU2. These results indicate that, under similar preexisting conditions and typhoon factors, the movement of ocean eddies under typhoon forcing is an unexpected mechanism that results in upwelling and thus needs to be considered when predicting changes in the ocean environment and typhoon intensity.

Atomic insights into the mechanism of trace water influence on lipase catalysis in organic media

Lipase catalysis plays an important role in bioengineering and food science and is widely used in the organic solvent environment. The addition of trace water to organic media can significantly change lipase activity, and the reason is essential to understand. In this study, by combining experiments and molecular dynamics simulations, we studied solvent-free acidolysis of the tripalmitin (PPP) with different water contents and revealed the mechanism of the water effect on lipase activity from atomic insight. Enzyme activity experimentally exhibited an increasing but subsequently decreasing trend with the rise of water content. Through molecular dynamics (MD) simulations, we found that the reaction activity was affected by three aspects: lipase flexibility, substrate diffusion and substrate spatial distribution. Lipase flexibility, as the structural basis of catalytic activity, increased with water content. At lower water content, the diffusion ability of the substrate around the lipase was dominant. With water content increasing, water molecules on the protein surface gradually shielded hydrogen bonds (HBs) between the oleic acids (OA) and the lipase, which improved the diffusion ability of the substrate near the enzyme surface and thus beneficial to the reaction occurring. At higher water content, the spatial distribution dominated the reaction, where the thicker water layer on the lipase surface acted as a spatial barrier hindering the access of substrate OA to the enzyme and thus harmful to the reaction. Our work helps to provide guidance on controlling enzyme activities in organic solvent systems.

Saturation Effect on the Coherency Loss of Spatially Varying Vertical Ground Motions

The effect of the influence regularity of site saturation and water level on the coherency loss between spatially varying earthquake ground motions (SVEGMs) in a vertical direction is not yet clear. Therefore, taking an onshore-offshore site as an example, the influence regularity of site saturation and water level on the coherency loss of SVEGMs in a vertical direction was studied, in which the saturation degree of the whole site (SD), the groundwater level (GWL), and the thickness of the surface water layer (WLT) were considered. Under each case mentioned above, a large number of vertical in-plane SVEGMs were synthesized and then correspondingly, the mean lagged coherency loss and phase angle of coherence function were obtained, and a series of comparisons were carried out to shed light on the varying trend of the value of lagged coherency loss and phase angle, with predefined parameters. The results showed that SD, GWL, and WLT possess significant effects on the varying trend of the coherence function of vertical SVEGMs.

Prediction of Run-Off Time for Water Film Thickness and the Effects on Wet Antenna Attenuation

Most of the reported works on wet antenna attenuation (WAA) focused on the estimation of the water-layer thickness without considering the time taken to be drained off from the reflector (that is, the runoff time). Simulated rain experiments was conducted on a parabolic antenna with a diameter of 0.6 m. Based on measurement data, this study examined the parametric effects of rain rate on water film thickness and runoff duration, and then associated those findings to the overall WAA. It was found that WAA increases with the water film thickness, while decreasing with the runoff time. More so, the latter quantity both increase with the antenna dish size. The study is useful in accounting for the WAA component in the overall link budget design for adequate service delivery.

Estimation of rain parameters for microwave backscattering model using PSO

The intention of the geophysical modelling of rain is to provide a better explanation for the effect of rainfall to the microwave backscattering and thus to interpret radar measurements. However, in the model, physical characteristic of raindrops should be estimated primarily and accurately by considering observation system, measurements and suitable rain rate retrieval algorithms to calculate backscattering coefficients from rainfall. In this study, a geophysical microwave backscattering model of rain type precipitation over sea surface is constructed by using Particle Swarm Optimization (PSO) algorithm in the multilayered Vector Radiative Transfer (VRT) model to estimate vertical profile of rain by using GPM DPR data. Rain column is partition into sublayers and for each sublayer, physical properties of raindrops such as drop radius, water volume fraction or layer thickness are estimated by using PSO to provide the best fit with measurements by searching within certain limits defined by rain rate. Backscattering coefficients from entire rain is provided by the solution of VRT equations via Matrix Doubling Method to consider multilayer effect. Results show that, vertical profile of rain parameters can be estimated accurately for moderate /high rain rates (up to 11–12 mm/h) by using presented model.

Two-color Method for Steel Temperature Measurement Unaffected by Water-induced Obstructions

Radiation thermometry, which enables non-contact temperature measurements of a moving target, plays a crucial role in temperature control during steel production. However, radiation thermometers implemented in manufacturing lines frequently encounter practical problems such as emissivity fluctuation, obstruction in the optical path, and background radiation. Herein, a new approach for solving the obstruction problem arising from the water in hot-rolling processes is presented. When a radiation thermometer detects the radiant flux emitted from a steel surface through unstable flowing water and evaporated water, the apparent transmissivity of these obstacles is unknown and it is extremely difficult to perform precise measurements. Thus, we propose a two-color thermometry technique that use specific wavelengths. A combination of wavelengths unaffected by the presence or absence of water in the optical path was studied both theoretically and experimentally. This two-color method enables simultaneous measurements of the water thickness. A prototype two-color thermometer was designed using detection wavelengths of 1200 nm and 1300 nm. The experimental results indicated that the temperature and apparent water layer thickness of heated steel beneath a water layer can be measured. It was also confirmed that two-color thermometry is useful for the obstruction of foggy steam.

The scattering of seismic waves from saturated river valley with water layer: Modelled by indirect boundary element method

River valley topography will cause local amplification effect and significant spatial variation effect of ground motion. In this paper, an indirect boundary element method (IBEM) is proposed to solve seismic wave scattering in sedimentary valleys. A ``water layer - soft sedimentary layer - poroelastic halfspace'' model is established, and the effects of water layer, soil parameters of sedimentary layer and terrain on incident P and SV waves are discussed in detail. The numerical results demonstrate that the scattering characteristics are closely related to the depth of water layer, porosity, the location of observation points, et al. The surface displacement amplitude decreases with increasing water layer thickness, with a maximum reduction of 16.2%. Moreover, the peak ground acceleration (PGA) is significantly larger and the seismic response is stronger when the observation point is located outside the valley compared to the observation point inside the valley. The influence of porosity on Fourier spectrum and response spectrum curve is mainly reflected in the peak value and predominant frequency. The research results can provide a theoretical basis for the seismic fortification of the structures around the saturated sedimentary valley.

Analysis of Unsteady Heat Transfer during Ice-Making Process for Ice Rink Buildings

The ice-making process is an important factor that affects the ice quality and the energy consumption of ice rinks. An unsteady heat transfer model is established and validated for the ice-making process. The transient temperature variation and ice thickness growing characteristics during the ice-making process are analyzed. The freezing time of a water layer and the final temperature of the stabilized ice layer are quantified. The effects of ice rink structural parameters on the ice-making process are studied. The results show that the water temperature variations during the process go through three stages. The ice-growing process mainly occurs in the second stage. The ice-making process takes about 305 min–420 min for a water layer of 5 mm thickness. The reduction in the ice-making time and the decrease in the final temperature of the stabilized ice layer can be attained by reducing the water layer thickness, the surface heat flux, the cooling pipe spacing, the fluid temperature in the cooling pipe, or the top concrete thickness. Among them, the influences of the thickness of the water layer, the surface heat flux, and the fluid temperature in the cooling pipe are more significant. As the thickness of the water layer decreases from 7 mm to 3 mm, the total ice-making time decreases by about 37.6%. The ice-making time is reduced by 17.1% with the surface heat flux decreasing from 330 W/m2 to 250 W/m2. The ice-making time is reduced by 21.4% with the cooling pipe temperature decreasing from −15.5 °C to −19.5 °C.

A mechanochemically created durable dynamic superhydrophilic‐like surface

Superhydrophilicity (superwettability) is generally defined as either a static water contact angle near 0° or water completely wetting the surface. Here, we show that there is a superhydrophilic‐like surface that has a large static water contact angle but demonstrates superhydrophilicity in its dynamic water contact performance. We found that polyethylene terephthalate (PET) surfaces showed such behavior following mechanical abrasion with sandpaper. We have evaluated the wettability of the abraded PET surfaces by using static water contact angle (SWCA) measurements and the dynamic water contact performance (DWCP) of impacting droplets, the latter including water sprays, water immersion, anti‐fogging and water droplet impact tests. The water was found to completely wet the abraded PET surfaces on spraying or immersion, although the measured SWCA was as high as 70°, similar to that of the unabraded PET surface. For the abraded PET surface, both the water layer thickness on water immersion and the subsequent drying time were similar to those of an especially coated superhydrophilic layer on the unabraded surface. Accordingly, superhydrophilicity may be determined by the process used to measure it.

Проницаемость слоя влажного сельскохозяйственного сырья при инфракрасном излучении, определяемая динамическим методом

The developed dynamic method of integral heat fl ux determination is based on the single-capacity dynamic model of the thermal state of the temperature measuring transducer (TMT), experiencing thermal infl uence of the constant infrared radiation fl ux and natural convective heat exchange of the TMT surface with the surrounding air. The model can help determine the permeability of moist agricultural raw materials. The eff ectiveness of the integral heat fl ux method was tested by studying the infrared radiation permeability of a layer of purifi ed drinking water with salinity not exceeding 1 g/l and a layer of apple pulp of the Golden-Deliches variety. The response of the temperature measuring transducer to infrared radiation was experimentally determined in series when the radiation was applied directly to the TMT and through a 3 mm thick sheet of monolithic polycarbonate. A 1 to 6 mm thick layer of water and a 1 to 10 mm thick layer of apple pulp were placed on the polycarbonate sheet in 1 mm increments. As a result of approximation of the experimental data obtained, the authors determined the maximum constant temperature value of the TMT and the time constant value of the TMT transient heating process. It was found that increasing the thickness of the water layer from 1 to 6 mm was accompanied by a decrease in the layer permeability from 0.804 to 0.629 in an exponential relationship with an exponent coeffi cient of -0.736. As the thickness of the apple layer increased from 1 to 6 mm, the permeability of the wet layer decreased from 0.780 to 0.097 according to an exponential relationship with an exponent coeffi cient of -0.399. The suffi cient heating duration for the spherical TMT was about 70 s and for the blackened fl attened TMT it did not exceed 30 s. The coeffi cients of the power-law ratio can be treated as attenuation coeffi cients in the Bouguer law for thermal radiation with energy maximum at wavelength λmax equaling 0.9 to 1.1 μm.

Autoregulatory of water level for channels of parabolic section and its capacity

The proposed design of the water level autoregulator with flexible working bodies for the channels of the parabolic section of the irrigation system is made in the form of a gate, which is a container formed by a rigid bottom, a pressure part made of flexible rubberized meliorative fabric, a rigid frame part of the spillway with a non-vacuum type profile covered with flexible meliorative fabric, and soft side elements also made of flexible rubberized meliorative fabric, which are a continuation of the pressure and spillway parts. Regulation of the water level in front of the autoregulator is carried out using a water level regulator. To determine the flow capacity of the gate of the proposed design of the water level autoregulator, a theoretical formula was derived, and experimental studies were carried out to determine the values of the flow coefficient included in this formula. The study was carried out on an experimental installation by the physical modeling method of the model and nature. As a result of the mathematical processing of the results of studies of the shutter model, an empirical formula was obtained for determining the shutter flow rate depending on the ratio of the iridescent water layer's thickness to the shutter's height. At the same time, the difference between the obtained values of the flow coefficients according to this formula and the results of experimental studies was +4...5 percent. This automatic water level regulator performs the function of a partition structure, does not require high costs, and can be portable and stationary; it is not metal-intensive, lightweight, transportable, combines the functions of stabilizing the required water level in the channel, dumping excess water, fin and debris, provides the necessary water enters the outlet openings of the channel.

Planar confined water organisation in lipid bilayer stacks of phosphatidylcholine and phosphatidylethanolamine.

Phospholipid-based liposomes are abundantly studied in biomembrane research and used in numerous medical and biotechnological applications. Despite current extensive knowledge on membrane nanostructure and its mechanical properties under various environmental conditions, there is still a lack of understanding on interfacial lipid-water interactions. In this work, the nature of the confined water layer for L-α-phosphatidylcholine (egg-PC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dimyristoyl-sn-glycerol-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) in the fluid lamellar phase of multilamellar vesicles was investigated. A new model for describing three different water regions is proposed, which have been characterised using a combination of small angle X-ray scattering (SAXS) and densitometry. The three regions concern (i) 'the headgroup water', (ii) 'perturbed water' near the membrane/water interface and (iii) a core layer of 'free water' (unperturbed water). The behaviour of all three layers is discussed as a function of temperature, concerning influences of chain saturation and headgroup type. While the overall water layer and perturbed water layer thickness increase with temperature, the free water layer displays the opposite trend for PCs, and in PEs is completely absent. Furthermore, an estimate of the temperature dependent headgroup orientation is given for both, PCs and PEs. The newly presented structural data deduced from the three-water region model will be useful for future refined molecular dynamics simulations and allow a better theoretical understanding of the attractive van der Waals force between adjacent membranes.

The role of body shape and mass in skimming on water

Over many years, there has been great practical interest in how solid bodies interact with and skim on liquid layers. In the present investigation, the focus is on the important role of body mass and shape in such skimming motions. Considering a thin two-dimensional solid body that impacts obliquely and then rebounds on a shallow inviscid water layer, we develop a mathematical model to predict quantitatively the duration and evolution of the body and fluid motions and indeed the success or failure of the whole skim. In the current setting, the shallow water layer thickness is small relative to the representative body length. The combined roles of increased mass and shape are found to be crucial, governed by a similarity solution. The relationship C ∼ M 2 / 3 between scaled body curvature and mass is identified and highlighted. In particular, increased convex curvature of the underbody is found to alter the interactive pressure in such a way that it inhibits the occurrence of a super-elastic response in the exit vertical velocity and height of the body, and in effect enables a much heavier body to skim successfully provided the above relationship is maintained.

Investigation on gas/water two-phase flow in quartz nanopores from molecular perspectives

Understanding the gas/water two-phase occurrence, flow patterns, and underlying mechanisms in quartz nanopores is crucial for gas transport and production in shale reservoirs. In this study, we investigated the flow characteristics of methane and water in hydroxylated quartz nanopores employing the grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations and focused on elucidating the effects of water saturation, pressure gradient and ion concentration in various aperture nanopores. Results show that water molecules preferentially adsorb on the hydrophilic quartz surface to form water film, increasing methane flow friction and reducing its slippage velocity significantly. Water bridges are formed to wrap gas bubbles and hinder the gas flow with increased water saturation. The water phase occupies a larger pore space with increasing water saturation resulting in an increase in methane effective viscosity and a decrease in apparent permeability. The water bridge is broken under the joint action of external force and gas driving when the pressure gradient is much larger, leading to a dramatic growth of gas flow, and the high-speed gas will produce a shear driving effect on the thick water layers. Ions will weaken the formation of hydrogen bonds between water molecules, but the flux of the water phase decreases with the increasing ion concentration due to the combined impact of ion spatial structure and electroviscous effects and counteracts the gas phase, thus impeding its flow. This study shed light on the flow phenomena of gas/water phases in hydrophilic nanopores. The results are expected to provide some insight into energy and environmental issues, such as fracturing fluid optimization, enhanced gas recovery (EGR) by water flooding, and the fabrication of microfluidic chips.

Galvanic Corrosion Between Coated Al Alloy Plate and Stainless Steel Fasteners, Part 2: Application of Finite Element Method and Machine Learning to Study Galvanic Current Distributions

Aluminum alloy panels joined with stainless steel fasteners have been known to occur in aerospace structures, due to their respective optimized mechanical properties. When connected via a conductive solution, a high-driving force for galvanic corrosion is present. The combination of the dissimilar materials, indicating galvanic corrosion, and complex geometry of the occluded fastener hole, indicating crevice corrosion, leads to the detrimental combined effect of galvanic-induced crevice corrosion, as investigated previously in Part I. The present work extends the validated finite element method (FEM) model to predict the current distribution and magnitude in a variety of geometric and environmental conditions, with the goal of preventing corrosion damage within the highly susceptible fastener hole. Specifically, water layer thicknesses ranging from bulk full-immersion (800 μm) to atmospheric (89 μm) conditions were investigated, as well as the impact of external scribe dimensions. Two avenues for mitigation were determined: (1) to force the majority of current away from the fastener hole and onto the bulk surface of the panel and (2) to lower the overall galvanic coupling current. A random forest machine learning algorithm was developed to generalize the FEM predictions and create an open-source applicable prediction tool.

VUV/UV oxidation performance for the elimination of recalcitrant aldehydes in water and its variation along the light-path

Vacuum ultraviolet/ultraviolet (VUV/UV) oxidation using a low-pressure mercury lamp emitting dual wavelengths (185 nm (VUV) and 254 nm (UV)) significantly varies in performance along the light-path (lP), which has not been fully characterized. Therefore, VUV/UV oxidation in solution was investigated at various lP in terms of the degradation kinetics and mineralization pathway of representative aldehydes with various alkyl-chain lengths. Oxidative degradation of parent aldehydes with shorter alkyl chains was less efficient, specifically the pseudo-zero-order rate constant (kobs) of formaldehyde was only 51% of that of propionaldehyde (kobs = 0.078 μM s−1). In contrast, the mineralization of aldehydes with longer alkyl chains was less efficient because these aldehydes underwent mineralization into more refractory carboxylic byproducts, e.g., oxalic acid. VUV was mainly absorbed by superficial water (lP < 0.55 cm), which resulted in highly heterogeneous oxidation in homogeneous water. Thus, kobs of acetaldehyde dramatically decreased from 0.13 to 0.033 μM s−1 as the total lP of solution increased from 1.0 to 3.0 cm. On the basis of mineralization pathways proposed above, an iterative kinetic model was developed to characterize the degradation of parent aldehydes and the formation of carboxylic acids along lP. This model predicted the VUV/UV oxidaton for the first time by considering the fast diffusion of pollutants by limited diffusion of transient radical species. Thus, it realized the prediction of •OH concentration at specific water solution and byproduct evolution within specific water solution in turbulent flow regime, wherein •OH was predominantly formed in superficial water-layers wherein •OH in water-layers of lP <0.16 cm and <0.81 cm contributed to 50% and 90% of the total oxidation performance, respectively. This result would help to improve the VUV-UV-reactor design in terms of optimizing the thickness of water-layer and turbulence of water-flow.

Электронная микроскопия дисперсной фазы дистиллированной воды

This article continues a series of works by the authors on the study of the dispersed phase of water using an optical microscope. Previously, it was found that each unit of the dispersed phase is a NaCl microcrystal surrounded by a thick layer of water of hydration, which prevents its dissolution. When free water evaporates from the glass surface, the osmotic pressure in the remaining water increases, which leads to the dissociation of hydration shells and contact of the salt with water. After complete evaporation, large NaCl crystals and gel-like non-evaporating water remain on the glass substrate. The use of a scanning electron microscope made it possible to reveal a number of previously unknown details: the formation of small crystals of sodium chloride on the surface of the dispersed phase of water and the growth of crystals on filaments of gel-like water. According to the authors, a significant part of NaCl in high-resistivity water is in the form of crystals inside the dispersed phase, which manifests itself after the evaporation of free water. The versions of other authors who observed "stable water clusters" in serially diluted solutions are discussed.

Insights from electrochemical crack tip modeling of atmospheric stress corrosion cracking

Crack tip electrochemical conditions are explored utilizing a reactive transport Finite Element Method model for stainless steel 304 exposed to 3 M NaCl. Under simulated full immersion conditions, a steady state pH of 3 and metal chloride concentration of 1.4 M were calculated. It was determined that an increase in cathode length and a decrease in water layer thickness increases total cathodic current per unit thickness, metal chloride concentrations, and decreases crack tip pH. The presented results and discussion call into question whether electrochemical similitude is achieved between different specimens, crack lengths, and between laboratory specimen and field relevant samples.

Deconvoluting the Surface Area and Geometric Effects of Fastener Heads on Galvanic Corrosion Prediction through FEM Modelling

Galvanic couples are common in commercial and military aerospace applications and arise from a difference in the substrate and fastener materials. These couples are often formed between aluminum alloys (e.g., AA7075-T6) with stainless steels (e.g., SS316L) or Ti-6Al-4V and can cause extensive corrosion damage to occur. This work uses laboratory techniques, including polarization curves and rotating disk electrode testing, to determine the kinetics of the electrochemical reactions. Collecting over a range of revolution rates on the RDE allows for the determination of the dependence of limiting current density due to oxygen diffusion at variable water layer thicknesses. Constructing geometries in commercial software that will be comparable to aerospace structures, coupled with experimentally-determined boundary conditions, allows for quantification and prediction of galvanic corrosion in aerospace applications. With the wide array of fasteners used, many material and geometric combinations are possible. This work focuses on the deconvolution of the impact of surface area and geometry on the prediction of the galvanic corrosion through the FEM software to better understand their effects.

Assessing the effect of a liquid water layer on the adsorption of hydrate anti-agglomerants using molecular simulations.

We have performed molecular dynamics simulations to study the adsorption of ten hydrate anti-agglomerants onto a mixed methane-propane sII hydrate surface covered by layers of liquid water of various thickness. As a general trend, we found that the more liquid water that is present on the hydrate surface, the less favorable the adsorption becomes even though there are considerable differences between the individual molecules, indicating that the presence and thickness of this liquid water layer are crucial parameters for anti-agglomerant adsorption studies. Additionally, we found that there exists an optimal thickness of the liquid water layer favoring hydrate growth due to the presence of both liquid water and hydrate-forming guest molecules. For all other cases of liquid water layer thickness, hydrate growth is slower due to the limited availability of hydrate-forming guests close to the hydrate formation front. Finally, we investigated the connection between the thickness of the liquid water layer and the degree of subcooling and found a very good agreement between our molecular dynamics simulations and theoretical predictions.