Erosive Action Research Articles

Surface Reconstruction of High-Voltage LiNi0.5Mn1.5O4 Cathode via the Sculpture Method toward Enhanced Stability.

High-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes suffer from severe capacity degradation during long-term cycling due the manganese dissolution and their high operating voltage (∼4.95 V), which pose serious challenges at the surface or interface. Moreover, both traditional ion-doping and passivation layer coating are difficult to apply consistently to LNMO cathode because of their complicated procedures, especially in large-scale production. To address these issues, a strategy employing HNO3/H2O2 leaching in synergy with a sintering process at a mid-temperature of 700 °C was used to achieve selective surface reconstruction. An optimal ratio of reactants was applied to balance the capacity and the cyclic stability of the LNMO cathode. The optimized valence composition of Mn on the material surface mitigates the occurrence of Jahn-Teller distortion, accompanied by a reasonable ratio of ordered and disordered phases and the concentration of oxygen vacancies after sintering, which improves the interface behavior between the electrode and electrolyte. This method delivers a high reversible capacity of 116.5 mAh g-1 after 200 cycles at 0.5 C (1 C = 147 mAh g-1) with a capacity retention of 91.30% and 110 mAh g-1 with a remarkably high capacity retention of 86.85% after 500 cycles at 2 C. This balanced approach, utilizing the protective effects of oxidation (O22-) and the erosive action of acid (H+), is proposed to achieve regional surface reconstruction of advanced LNMO cathode. This opens up a strategy for improving oxide-based cathode materials with low cost and mass production capability, especially favoring high consistency.

Performance Evaluation and Mechanism Study of Solid Waste-Based Cementitious Materials for Solidifying Marine Soft Soil under Seawater Mixing and Erosion Action

The main purpose of this research is to develop a solid waste-based cementitious material (SWC) instead of cement for solidifying a large amount of marine soft soil with high water content and low bearing capacity in coastal areas. This aims to solve the problems encountered in the practical application of cement soil, such as slow strength growth and poor durability. The SWC includes ground granulated blast furnace slag (GGBS), dust ash (DA), and activated cinder powder (ACP), with admixtures of naphthalene sulfonate formaldehyde condensate (NS) and compound salt early strength agent (SA). Both the 7 d and 28 d compressive strength values of the SWC formulations G4 and G7 are about twice as strong as those of cement soil (GC), even when mixed with seawater. Immersion tests revealed that stabilized soil had superior resistance to seawater corrosion compared to cement soil. X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis explained that the main hydration products in cement soil are C-S-H and CH, while in stabilized soil, SWC generates a large amount of C-A-S-H with gelling properties and AFt with filling properties. These hydration products have better effects on strength and seawater erosion resistance.

Closer Approach towards the Preparation of Cellulose and Microcrystalline Cellulose from Corn Husks

AbstractIn this work, cellulose was effectively produced from corn husks by a simple and eco‐friendly method. Major influencing variables for cellulose extraction were examined, and the highest yield of lignin and hemicellulose cleavage was achieved after corn husks were treated in 12.5 wt % NaOH solution at solid/liquid ratio (S/L) of 1:10 g mL−1, 70 °C for 90 min. Subsequent bleaching conducted in 10 wt % H2O2 solution at 80 °C for 90 min produced cellulose with a lightness value (L*) of ∼87, chromaticity indexes a* = −1.85, b* = 2.94 with high purity, 90.86 %, and crystallinity, 64.94 %. Fourier transform infrared, scanning electron microscopy, and x‐ray diffraction analysis showed a clear transition in morphology, structure modification, and crystallinity consistent with the alteration of the chemical composition from raw material to delignified residue and the bleached one. To synthesize microcrystalline cellulose (MCC), the hydrolysis was investigated in H2SO4 solutions of different concentrations and durations via monitoring particle size distribution by laser diffraction spectroscopy. At the most efficient conditions (30 wt % H2SO4, 18 h, 45 °C, 1:10 S/L ratio), the obtained MCC reached an average particle size of 42.68 µm, crystallinity degree of 61.6 %, and cellulose purity of 92.5 %. Meanwhile, similar parameters with 4 N HCl solution produced MCC with the same purity but higher crystallinity (65.6 %), higher mean size, 67.62 µm, and higher aspect ratio. SEM images showed that 4 N HCl caused less detrimental and erosive action, and less fragmentation on cellulose microfibrils compared to 30 wt % H2SO4. The study's outcome supports the feasibility of corn husks to produce cellulose and MCC for further applications.

Joint utilization and harmless elimination of aluminum dross and refined magnesium slag to simultaneously recover metallic aluminum and fusing agent

Refined magnesium slag and aluminum dross are two typical hazardous solid wastes that contain significant amounts of leachable fusing agent and aluminum droplets encapsulated by dense oxidized films, respectively. This study creatively proposes a safe and green method for the joint utilization of these two wastes. The interfacial reaction behavior revealed that the dense oxidized films of the aluminum droplets were significantly broken by the erosive action of the fusing agent, providing the necessary conditions for the movement of aluminum droplets. Consequently, the aluminum droplets successfully broke free from the oxidized films and separated together with the fusing agent from the dross under the force of supergravity. The recovery ratios of metallic aluminum and fusing agent reached 98.95 % and 98.13 %, while the aluminum and fusing agent contents in the tailings were reduced to 0.82 wt% and 3.71 wt%. The study also discusses the leaching characteristic of the tailings and the scalability for industrial applications of this method in detail. This study not only achieves valuable resource recovery but also reduces the leaching risk and alleviates the land occupation and ecosystem pressure caused by industrial wastes. The tailings can be harmlessly utilized in related fields through subsequent scientific treatment.

Durability performance of superabsorbent polymer incorporated concrete modified by nano-silica addition in seasonal frozen regions

In seasonal frozen regions, ion erosion and freeze-thaw (F-T) cycles threaten pavement concrete durability. This study evaluates the suitability of superabsorbent polymer (SAP) concrete modified by nano silica (NS) for enhancing durability. Tests were conducted to analyze chloride impermeability and frost resistance effects on modified SAP concrete. The coupling impact of ion erosion and freeze-thawing was also evaluated. Mercury intrusion porosimetry (MIP), scanning electron microscopy, and energy dispersive spectrometry were employed to investigate microstructure characteristics. Results demonstrated that NS-modified SAP concrete exhibited high resistance to ion erosion and F-T cycles. Adding 3 % NS reduced the relative dynamic elastic modulus (RDEM) loss by 23.21 % after 300 F-T cycles. The enhancement was more pronounced under the coupled action of ion erosion and freeze-thawing, and the RDEM loss and scaling quantity per unit area of NS-3 % decreased by 13.21 % and 41.48 % respectively, and compressive strength was 28.33 % higher than that of SAP concrete after 135 salt-frost cycles. MIP testing indicated that 3 % NS significantly improved pore structure, reducing deterioration in much harmful pores by 12.82 %. SAP promoted the efficient pozzolanic reaction of NS, generating high-density C-S-H. Additionally, second-hydration products were adsorbed by the ionization of SAP microgel, densifying its shrinkage voids and delaying ITZ width and micro-crack propagation, thereby enhancing concrete durability.

Pore fractal characteristics and ANN model of polyacrylonitrile fiber reinforced concrete under the synergistic effects of freeze-thaw and erosion

The degradation of the concrete pore structure is a major concern among scholars due to its negative impact on durability. This study conducted a salt freezing test on polyacrylonitrile fiber concrete (PANFRC) using a composite freeze-thaw medium consisting of Na2SO4, MgSO4, and NaCl (5 % + 5% + 3.5 %). The pore volume fractal dimension was determined by analyzing the T2 spectrum obtained through nuclear magnetic resonance technology. The study explored the influence of different types of pores on frost resistance and developed an artificial neural network-based machine learning model to predict macroscopic frost resistance using the pore volume fractal dimension. The experimental findings indicate that plain concrete exhibits a density loss of 4.67 % upon failure, whereas the density loss in PANFRC is reduced to less than 3 %. The frost resistance durability index is observed to improve as the fiber mass fraction increases within specific ranges. Notably, when the fiber content surpasses 1.2 kg/m³, the durability factor (DF) can be effectively doubled. Drawing from the concept of freeze-thaw cycles, a novel frost-thaw erosion damage model was developed, which incorporates the influence of fiber content under the combined action of freeze-thaw cycles and erosion. The analysis of pore dimensions reveals that the fractal characteristics become more pronounced with the increase in pore size, although this does not extend to the micro-pore range (i.e., those smaller than 0.1 μm). In comparison to other machine learning algorithms, the ANN demonstrates its superiority by establishing a meso-macro transfer prediction model with enhanced generalization capabilities.

A damage constitutive model of layered slate under the action of triaxial compression and water environment erosion

Based on the macroscopic structure control theory, The slate with a significant bedding plane is a composite rock mass composed of rock blocks containing microscopic defects, joint surface closure elements, and shear deformation elements. Considering the coupling damage effect of water erosion and triaxial compressive load on bedding structure plane, the transversely isotropic damage constitutive model of slate under triaxial compressive load is derived with the dip angle of bedding and confining pressure as the variable. Firstly, based on the statistical theory of continuous damage mechanics and the maximum tensile strain criterion, the transversely isotropic deformation constitutive model of rock block with micro-defects is given; Secondly, based on the phenomenological theory of closed deformation and shear-slip deformation mechanism of layered structural plane under the coupling action of water erosion and triaxial compression load, the calculation formula of axial deformation of layered structural plane under the coupling action is given; Finally, to verify the accuracy of the established constitutive model, triaxial compression tests are carried out to study the influence of dip angle and confining pressure on the macroscopic mechanical properties and mechanism of slate. The results show that: the established triaxial compression damage constitutive model of bedding slate can accurately describe the stress–strain relationship of bedding slate after water environment erosion. With the increase of bedding dip angle, the strength and deformation capacity of the bedding slate first decreases and then increases, showing a U-shaped distribution as a whole. There are three main types of failure: tension shear composite failure, shear slip failure, and splitting tension failure.

Nomograph development for water erosion quantification in Wadi Cheliff’s catchment, Northern Algeria

Water erosion study is regarded as one of the most important axes in scientific researches. The erosive effect of water on the surface layers can have major consequences on soil loss and land degradation. The objective of our work was the development of a water erosion nomograph that represents a practical and precise tool that is adapted to local conditions for a direct quantification of erosive action in the absence of basic data. Regarding the magnitude of the phenomenon in Algeria, the catchment of Wadi Cheliff was taken as an experimental site where a significant spatio-temporal variability of liquid and solid flows was observed and the measurement network in different locations was either dispersed or non-existent. The developed methodological approach permitted the identification of 149 experimental sites (20 hydrometric stations, 15 large dams and 114 hill dams) where existing data allowed the erosion quantification. A flow coefficient variography was performed in addition to a principal component analysis (PCA), leading to the identification of three distinct groups. Moreover, the modeling of the studied variable was achieved through the application of multivariate analysis to the third group of 100 observations. Applying the principles of nomography on the final model, a nomograph of the semi-arid area of Wadi Cheliff catchment was realized for surfaces ranging from 500 to 25 000 ha. This nomograph enabled the direct quantification of water erosion from the product (Es1 Es2), taking into account the area of the catchment, its average slope and its flow coefficient with a mean absolute percentage error (MAPE) of 2%.

Experimental study of reservoir flushing through a bottom tunnel initially covered by cohesive sediment

Reservoir sediment flushing, one of the most effective strategies for alleviating reservoir sedimentation, involves discharging sediment-laden flows downstream through bottom tunnels. However, whether flushing can be accomplished if the intake of a bottom tunnel is initially covered by cohesive sediment remains poorly understood. Here, flume experiments were done to investigate cohesive sediment flushing in a reservoir. It is demonstrated that cohesive sediment in a reservoir is harder to flush than non-cohesive sediment. A higher water level in the reservoir, initially smaller cover layer thickness, and lower dry density of the sediment favor the occurrence of sediment flushing. The flushing process of cohesive sediment is significantly affected by seepage. Under the combined action of gravity erosion and water erosion, the scour hole upstream of the dam is characterized by angular and broken edges. The threshold conditions for flushing of non-cohesive and cohesive sediments are evaluated. Empirical formulas applicable to both non-cohesive and cohesive sediment are proposed to estimate the equilibrium scour depth immediately upstream of the bottom tunnel intake. Also, empirical models are proposed for the time variation of sediment position in the bottom tunnel. The current findings are significant for informing the design and operation of reservoirs on rivers carrying fine-grained cohesive sediment in support of reservoir benefits and capacity preservation.

Study on the Degradation Effect of Carbonaceous Shale under the Coupling Effect of Chemical Erosion and High Temperature.

The southwest region of China has abundant groundwater and high-temperature geothermal energy. Carbonaceous shale, as one of the typical surrounding rocks in this region, often suffers from deterioration effects due to the coupled action of groundwater chemical erosion and high temperature, which affects the long-term stability of tunnel engineering. In order to investigate the deterioration effects of carbonaceous shale under the coupled action of chemical erosion and high temperature, carbonaceous shale from a tunnel of Lixiang Railway in Yunnan Province was taken as the research object. The microstructure and mineral composition of the samples before and after chemical erosion were obtained with a scanning electron microscope-energy dispersive spectrometer and an X-ray diffraction test. Then, triaxial compression tests were conducted on the samples under different time points and different temperature effects of chemical erosion, and the stress-strain curves and the deterioration laws under a single factor were obtained. An improved numerical simulation method based on the parallel bond model was developed, which can account for the coupled effects of chemical erosion and high temperature on the rock. By simulating the triaxial compression test of carbonaceous shale, the deterioration law of carbonaceous shale under the coupled action was discussed. The results show that chemical erosion has a significant deterioration effect on the triaxial compressive strength of carbonaceous shale, and the degree of deterioration is related to the erosion time. In the first 30 days of erosion, the triaxial compressive strength of carbonaceous shale decreased by 11.38%, which was the largest deterioration range. With the increase in erosion time, the deterioration rate gradually decreased; temperature had a significant threshold effect on the strength of carbonaceous shale, and a clear turning point appeared at about 200 °C. By simulating the deterioration effects of carbonaceous shale under the coupled action of chemical erosion and high temperature, it was found that the longer the duration of chemical erosion, the stronger the temperature sensitivity of carbonaceous shale, and the more serious the loss of compressive strength during the heating process. When the temperature was low, the strength of carbonaceous shale changed little, and some samples even showed an increase in strength; when the temperature was high, the strength of carbonaceous shale decreased significantly, showing deterioration characteristics. The numerical simulation method was compared and verified with the indoor test results, and it was found that the numerical calculation had a good agreement with the test results.

An Experimental Study on the Effect of Distance and Sheltering Area of a Group of Linearly Arranged Sacrificial Piles on Reducing Local Scour around a Circular Bridge Pier under Clear-Water Conditions

One of the major problems associated with bridge piers is ensuring their safety against local scouring caused by the erosive action of flow. Numerous countermeasures have been developed and tested to solve this problem, among which sacrificial piles are highly recognized due to their high performance, economy, durability, and ease of construction. Several factors affect the performance of sacrificial piles, such as their number, size, degree of submergence, and geometric arrangement parameters. In this study, the performance of a group of linearly arranged cylindrical sacrificial piles in reducing local scour around a circular bridge pier was investigated by varying the number of piles (or sheltering area) and distance between piles and the pier under clear-water conditions. Three values of distance between piles and the pier and three values of sheltering area (or number of piles) were tested. The efficiencies of sacrificial piles in different configurations were presented in terms of the percentage reduction in maximum scour depth at an unprotected pier under the same hydraulic conditions. The results of this experiment show that when linearly arranged sacrificial piles are placed close to the pier (at distance D; D is the pier diameter), an increase in the number of piles (or sheltered area) results in an increased scour depth, and when placed far from the pier (2D and 3D), an increase in the number of piles results in a decrease in scour depth around the pier. In addition, for 40% and 60% sheltering conditions, scour depth increased with an increase in the spacing between piles and the pier, while for 80% sheltering conditions, optimum protection was observed at a distance of 2D. Overall, two piles placed at distance D provided optimum protection with a scour depth reduction of 41.6%, while minimum protection was recorded when the same were placed at a spacing of 3D from the pier (25.5%).

Impact of Acid, Salt, and Wetting-Drying Cycles on Weathering Deterioration of the Red Sandstone Used for Leshan Giant Buddha China

ABSTRACT The red sandstone of the well-known Leshan Giant Buddha is currently undergoing a severe deterioration threat such as frequent wetting-drying cycles, seasonal and occasional acid rain, and widespread sulfate attacks. The variations in the physical properties of the red sandstone and the hydrochemistry of the soaking solution through an accelerated simulation experiment were comprehensively analyzed in the present manuscript, aiming to investigate and gain insights into environmental weathering impact and deterioration mechanisms on the Leshan Giant Buddha. The results presented that the wetting-drying cycle would significantly decrease the physical and mechanical performances of the red sandstone due to the water-rock interaction and the acid or salt compound undoubtedly aggravated this deterioration process. Thereinto, acid corrosion promptly occurred on the surface of red sandstone and ceased upon depletion of the acid compound, which was deemed as a short-term corrosion, while the sulfate attack was a long-term and repeated process damage caused by the swell stress from salt crystallization. Furthermore, a synergistic and mutually reinforcing relationship was established among the coupling actions of water-rock erosion, acid rain corrosion, and sulfate attack, resulting in serious weathering and deterioration that compromised both the historical and cultural significances of the Giant Buddha statue. According to the findings from this work, the application of appropriate weathering prevention materials for waterproofing and desalination should be considered to safeguard the red sandstone, while the optimization of diversion ditches and reconstruction of the covering buildings were the key to prevent the world heritage site Leshan Giant Buddha.

Flow enhanced corrosion of tee in gas transmission pipeline

A tee failed due to flow enhanced corrosion at an oil field was investigated and analyzed by macroscopic analysis, nondestructive tests, material tests (including chemical composition, metallurgical analysis) and microstructure analysis (including microtopography, SEM, EDS and XRD) in this paper. It was concluded that the chemical composition and metallurgical properties of the tee accord with related standards, and the anti-corrosion coating on the inner wall peeled off is considered as one of the main failure factors of tee. The corrosion failure mechanism analysis results shows that the change of flow pattern caused the sudden change of the inner diameter between weld reinforcement and nickel based coating results in water gathering and flow enhanced corrosion at the concave area. Also, galvanic corrosion occurs at the concave area formed by weld reinforcement and nickel based coating between the carbon steel tee and nickel based coating due to high electrode potential difference. The galvanic corrosion further accelerated the corrosion process. Under the combined action of erosion, galvanic corrosion and flow enhanced corrosion, perforation leakage finally occurs.

Submerged pulsating water jet erosion of ductile material

This article deals with the manifestations of erosion of statically acting concentrated multiple droplet impingements on materials over different lengths of time in order to assess the erosion evolution when the materials are submerged, as compared with the action of droplets on the materials under atmospheric conditions. The study aims to determine the extent of the erosive effects of droplets in underwater conditions. Experiments were conducted in a plastic pool in which the water level was varied from h = 80 to h = 120 mm to identify the effect of hydrostatic pressure at p120 = 0.1025 MPa and p80 = 0.1021 MPa. The results were compared with that of a control group of samples obtained under atmospheric air conditions. To observe the erosive damage evolution, 15 (n = 5) sites on the ductile materials EN AW-Al 99.5 and CW004A were exposed to high-intensity droplet impingement at defined exposure times. The exposure time varied from 0.125 s to 1.875 s, with increments of 0.125 s. As a droplet generator, an ultrasonic pulsating water jet with a frequency f = 20 kHz, a pressure p = 30 MPa and a nozzle diameter d = 0.4 mm was used to achieve the theoretical subsonic speed of the droplets. The results exceeded the assumptions regarding the possible attenuation of water pulses. It was found that under the theoretical speed of the jet vw = 225 m/s, the submerged condition causes attenuation in its erosive action. The incident area in the case of submerged treatment was more symmetrical. The erosion shift in term of prolonging incubation erosion stage was found to be a result of the increasing hydrostatic pressure. The results suggest that this method can also be used under submerged conditions for treatment or material drilling.

Study on the Influence of Urban Water Supply Pipeline Leakage on the Scouring Failure Law of Cohesive Soil Subgrade

Urban water supply pipelines serve as vital lifelines for urban operations. However, the occurrence of underground pipeline leakage, caused by various factors, results in significant water loss and gives rise to safety hazards such as pavement collapse due to the erosive action of leaking water on the overlying soil. To conduct a more comprehensive investigation into the erosion characteristics of the leaking jet on the soil, this study employed a custom-built soil-test system to investigate the erosive effects of leakage from the water supply pipe network on the clay roadbed above. The study considered water flow rate, leakage port size, and leakage angle as influential factors. The experimental results demonstrated that reducing the water flow rate significantly enhances the soil’s erosion resistance. There is a positive correlation between the caliber of pipe leakage, pipe diameter, and the erosion rate of the soil cavity. Under identical conditions, the erosion rate of the specimen increased consistently with an increase in the leakage port angle. The study also investigated and summarized the curve depicting the formation of soil cavities. The aforementioned findings offer valuable insights for the implementation of reinforcement measures using fine-grained cohesive soil backfill in urban water supply pipelines.

STUDY OF CORROSION-MECHANICAL RESISTANCE OF REINFORCING STEEL INTENDED FOR OPERATION IN HYDROTECHNICAL STRUCTURES

Analytical review showed that duringthe long term of operation of reinforced concrete structures of hydraulic tructures, their individual elements, such as reinforcing rods, are destroyed due to insufficient fatigue and corrosion resistance of the metal of the reinforcement. They arise mostly under the action of the main variable loads - bending, vibrations of reinforced concrete slabs, mechanical and erosive actions of the environment.The main reasons for the destruction of reinforcement are its rupture and wear as a result of repeated action of force factors. The surface zone of the reinforcement in the connection with concrete is especially intensively destroyed due to weak bondstrength. One of the reasons for the destruction of reinforcement joints with concrete can also be the use of low-strength reinforcing steels. An increasein the corrosion-mechanical reliability of reinforced concrete structures of hydrotechnical structures is possible due to the use: for the manufacture of reinforcing rods, which are the main strength structure of reinforced concrete, economically modified alloy steels that undergo complex heat treatment and arecharacterized by high corrosion-fatigue properties when working in aggressive environments with cyclic ( sign-changing) loads.The studied resistance against SCRN, VIR and corrosion-mechanical fatigue of reinforcing steels intended for the construction industry. It was established that experimental steels economically modified with REE, copper, nickel, especially chromium, niobium, and vanadium meet the requirements of the International Standard NACE MR0175-96 in terms of chemical composition and mechanical properties, and steels of grades 10ХСНДАand 20Ф do not have a sufficiently high resistanceof the SCRN (limit stresses < 0.8 ∙σ0.2min) and corrosion-fatigue failure, and steel grades 20F and 06G2B showed low VIR resistance (CLR > 6% and CTR > 3%). Therefore, a full (100%) input controlof the corrosion-mechanical resistance of all materials involved in the production of reinforced concrete structures for hydrotechnical purposes for operation in hydrogen sulfide-containing environments should be carried out.

Influence of perennial grasses usage duration on fertility of irtysk oma meadow-black earth soil

Studies were carried out in order to establish the in uence of legume- cereal grass mixtures on the fertility indicators of irrigated meadow- chernozem soil, depending on the duration of their cultivation in grain- grass crop rotation. Two factors were studied in the experiment: A - grass mixture: 1) awnless brome + alfalfa 6 years old, 2) awnless brome + eastern goat’s rue + eastern goat’s rue 12 years old, 3) awnless brome + eastern goat’s rue 21 years old; B - mineral fertilizers: 1) without fertilizers. Nitrogen fertilizers were applied for each of the two mowings, and phosphorus fertilizers were applied as reserves. The dependence of the amount of agronomically valuable aggregates and their resistance to water erosion action on the age of legume-bluegrass grass mixtures was revealed. With an increase in the age of herbs, the number of these aggregates in the soil layer 0…20 cm increased from 48 % under the grass mixture of 6 years of life to 69 % under the grass mixture of 12 years, reaching 79 % under the grass mixture of 21 years of life. When introducing nitrogen-phosphorus fertilizers, a decrease in fractions of agronomically valuable aggregates under the grass stand of 12 and 21 years of life was established by 7…9 % in relation to options without fertilizers. With the increase in the age of grass stand, the content of humus and humic acids in its composition, exchange cations and the reaction of the medium did not change significantly, to a greater extent the changes are associated with the influence of mineral fertilizers. The amount of humus under the herbs in the soil layer 0…20 cm was high and reached 6.7…7.1 % in fertilized versions and 7.5…7.8 % in versions without fertilizers. In the composition of humus, the share of humic acid carbon accounted for from 1.9…2.4 to 2.6…2.7 %, respectively, options. The reaction of the medium in the test variants varied from 5.8 to 6.8 units of pH the aqueous suspension. In the composition of exchangeable cations, calcium accounted for 70 to 87 %. In the experimental variants without fertilizers, the content of mobile phosphorus (according to Chirikov) in the soil was 55…90 mg/ kg; when applying fertilizers, its amount increased by 68…95 mg/kg in a layer of 0…20 cm and by 40 …70 mg/kg in a layer of 20…40 cm. Indicators of the chemical and physicochemical properties of the soil reached optimal parameters after 6 years of cultivating the legume-poa grass mixture, so further use (12 and 21 years) of the soil under grass is not practical.

Water droplet erosion assessment in the initial stages on AISI 316 L using kernel average misorientation

Surfaces exposed to natural forces in the form of water droplets are structurally deformed over time through changes in their surface morphology. Plastic deformation in thin subsurface layers where compressive stress prevails is typical for this stage of erosion. The stress accumulation does not exceed the fatigue limit, so the structural integrity is not broken. Information about this stage has been obtained by post-experimental assessments using various observation techniques. This article considers the changes to a surface using techniques to assess a specific site before and after exposure to the erosive action of water droplets. An electron backscatter diffraction analysis was conducted pre-exposure of water droplets for detection on an electrochemically polished surface of stainless steel AISI 316 L. Specific areas that were exposed to the effects of water droplets at subsonic speed were marked with indents. The droplets were generated by an ultrasonic pulsating water jet (PWJ) with a nominal frequency of 40 kHz and supply pressure of p = 50 MPa. To assess the development in the very early stages of erosion, individual runs were performed with a time range of 1–3 s. The erosion development was compared with control runs, where a continuous water jet (CWJ) with a frequency of 1 Hz was used with a time range of 3–6 s. A post-exposure electron backscatter diffraction analysis showed a real change in the grain orientation using kernel average misorientation. It was found that multiple droplet impingement changes the grain geometry and results in an increase in misorientation inside the grains. The misorientation distribution in the zone treated by the water jet was not homogeneous over the entire cross-section of the sample; the CWJ required double or even triple the time to achieve a similar level of plastic deformation when compared to the PWJ.

Morphodynamics of two Mediterranean microtidal beaches presenting permanent megacusps under the influence of waves and strong offshore winds

This study focuses on four years of survey of two low-microtidal emerged beaches (average tidal range ≈ 0.3 m), presenting permanent megacusps on the French Mediterranean coast. These beaches are representative of the southern part of the Gulf of Lion (45 km of coast): the Leucate beach backed by a small dune and the La Franqui beach backed by a small lagoon. An analysis of the hydrodynamic and meteorological forcing along with morphological changes allows to define the key parameters controlling the system. These results are used to develop a conceptual model composed of five main situations and then compare it to the microtidal literature. Dominant offshore winds can reach speeds of up to 20 m s−1 (Gusts up to 30 m s−1) and have an erosive action on the backshore and produce advance of the shoreline of a few metres. This shoreline advance is mainly concentrated on the horns when it is concomitant with small fair-weather waves. Waves of moderate to high intensity (storms) lead to strong erosion and steepening of the beach face, as well as the migration or construction of a new higher berm located landward and associated with sediment deposition on the upper beach. The low tidal range may also allow the high run-up level to stabilise for a longer period of time in a high elevation on the backshore. The alternation of storm episodes and offshore wind periods could control the relative stability of the emerged beach.

Modelling and simulation of MRR in electro-chemical surface grinding of Al-SiC-Gr using hybrid analytical approach

Electro-Chemical Surface Grinding (ECSG) is a hybrid machining process which utilizes synergic actions of three sub-processes viz. electrochemical dissolution, grinding action of abrasive particles and erosive action of electrolyte flow in inter electrode gap. Since, occurrence of turbulence in machining zone significantly affects the machining performance, it is required to analyze the turbulence phenomenon in ECSG process. The exact solution and Numerical solution–based hybrid analytical approach has been used to predict the Material Removal Rate (MRR) in ECSG of Al-SiC-Gr. In this model, the streaming potential of electrolytic action, abrasive action of grinding wheel and shear force of electrolyte flow between inter electrode gap have been considered. Finite Element Method based Numerical modelling has been carried out to analyze the electrolyte flow in machining zone in order to evaluate the MRR due to erosive action. It was observed that the application of shear force on oxide layer rises with the increase in flow rate of electrolyte. Confirmation experiment has been performed to validate the modelling results. Validation results show a minor error of 8.21% in prediction of MRR using analytical as well as finite element model.