Erosion Damage Research Articles

Clinical aspects of pathology of the upper gastrointestinal tract in military personnel of the North Caucasian District of the Russian Guard, participating in combat operations

BACKGROUND: The use of modern technology and weapons forces us to reconsider classical approaches to the prevalence and understanding of the specifics of the existing pathology of participants in hostilities and providing them with medical care. AIM: To study the prevalence of pathology of the upper gastrointestinal tract in servicemen of the North Caucasian District of the Russian Guard, participating in hostilities, and their clinical features. DESIGN OF THE STUDY: 118 participants in combat operations were examined, all men aged 21 to 65 years, 48 officers and 70 military personnel of the contract service with a background mild surgical and therapeutic pathology and a burdened gastroenterological history. Statistical processing of the results was carried out using the variable frequency method in the MedCalc Statistical Software version 22.009 (MedCalc Software Ltd, Ostend, Belgium; https://www.medcalc.org; 2023). RESULTS: In patients participating in combat operations (at р 0.0001), acute and chronic erosive and ulcerative destructive damage to the mucous membrane in the gastrointestinal tract prevails (61%), chronic superficial gastritis occurs in 19%, GERD in 15% and functional dyspepsia in 5%. Among officers, acute gastric erosions, combined erosive-ulcerative pathology and chronic gastritis were more common; among contract military personnel, chronic duodenal ulcers, the erosive form of GERD, chronic gastritis and combined pathologies predominated. CONCLUSION: Participants in combat operations are susceptible to erosive and ulcerative lesions in the gastrointestinal tract and require close attention with an emphasis on a group of officers, as well as the creation of modern clinical and diagnostic programs for the early detection of diseases of the upper parts of the digestive organs to prevent delayed complications.

Cavitation erosion behaviour of MAB-CU4 alloy: influences of cavitation number, attack angle, time, and stand-off distance

Abstract The present study comprehensively examines the cavitation erosion behaviour of a manganese aluminium bronze alloy (MAB-CU4 alloy) as a function of several parameters (i.e., cavitation angle, cavitation number, time, and stand-off distance), particularly focusing on the influences of cavitation angle on the surface morphology and topography of the alloy. According to the design of experiment (Taguchi experimental design) analysis, mass loss increased with cavitation number and attack angle, while increasing the stand-off distance resulted in a decrease in mass loss and an increase in the surface area affected by cavitation erosion. Cavitation erosion behaviour was most affected by the cavitation attack angle, with the cavitation attack angle contributing 69.1% to total erosion, according to variance analysis. At 90° cavitation attack angle, MAB-CU4’s erosion rate was 64% greater than that at 30°. Scanning electron microscopy and optical profilometry revealed that cavitation erosion damage at 90° occurred mostly in the grain interiors as cavitation pits due to severe plastic deformation and surface corrosion, whereas pit formation was restricted around the hard secondary phases at the grain boundaries. At 30°, deep cavitation pits were limited, the erosion crater expanded, and the number of pits was reduced. Overall, finer microstructures with more grain boundaries and secondary phases may improve cavitation erosion resistance at 90°. The present study is the first to comprehensively capture erosion damage at the microstructural scale and analyse the impact of microstructural features on the erosion damage during the cavitation erosion of MAB-CU4 alloy.

Aging damage characteristics of acid‐etched sandstone samples

AbstractTo investigate the erosive damage effect of the acidic solution on sandstone, experiments were conducted to examine the macro‐ and micro‐characteristics of sandstone samples under different acid etching times. Microscopic morphology changes, pore structure characteristics, mineral composition changes, and mechanical response characteristics were obtained before and after acid etching. Finally, a comprehensive evaluation index for acid etching damage was proposed. The results show that: (1) Acidic solution will erode the sandstone skeleton and cause the sandstone to collapse. The etched surface appears “flocculent” and yellow sediment is produced. (2) The pores in sandstone samples are mainly micro‐ and mesopores, and the total porosity increases exponentially with the duration of acid etching. The volume fraction of micropores can reach up to 81.5%. (3) The acid etching process of sandstone samples includes physical diffusion and chemical dissolution, which can be divided into four stages and three regions from the outside to the inside. After acid etching, the uniaxial compression failure mode of the sample changes from shear to mixed shear‐tensile failure. (4) The comprehensive evaluation index based on three failure modes generated during the loading process shows good consistency with the overall changes of characteristics parameters such as elastic modulus, peak stress, and peak strain. The research findings of this paper can provide theoretical support for the assessment of rock mass stability and disaster prevention in acidic environments.

CFD-DEM study on the blocking conformation of pre-filled sand control screen by layering method

Preventing screen blockage due to sand poses a significant challenge. The article combines computational fluid dynamics (CFD) and discrete element method (DEM) to establish a fully coupled four-way interaction model. A sophisticated size particle injection model was established, taking into account the particle size distribution (PSD) characteristics of the formation. A layering method was used to study the sand control behavior of a high-performance pre-filled screen. The study also quantitatively investigated the impact of factors such as median sand size (D50), screen structure, and fluid velocity on both wellbore-screen annulus and internal screen plugging patterns. The findings reveal that the sand retention rate within the wellbore-screen annulus exceeds 93.8 %. The risk of pre-filled screen blockage is minimized when the ratio of gravel diameter to sand diameter falls within the range of 3.3–5. At a gravel filling rate of 97 %, fine sand predominantly moves radially, resulting in a low risk of blockage at the screen's entrance layer, thereby favoring oil and gas production. In cases with elevated fine sand content, it is advisable to maintain a production flow rate below 3 m/s to mitigate localized erosion damage caused by increased pressure resulting from screen blockage. This model holds significant importance in optimizing completion tools and production parameters.

Insights into the relationship between particulate flow characteristics and local erosion behaviour under waterjet: The role of particle-fluid-surface interaction

In this study, the erosion characteristics of eutectic high entropy alloy under the liquid–solid two-phase flow is investigated by a coupled numerical-experimental method, in order to reveal the intrinsic relationship between microscopic erosion mechanism (experimental test) and the related particle-fluid-surface interaction (CFD modelling). Furthermore, instead of the common relation between average erosion rate and mainstream flow velocity, the relationship between local erosion distribution and local particulate flow characteristics is clarified. The erosion rate and erosion pattern match well between the experiment and simulation. The results demonstrate that NiCoCrFeNb0.45 exhibits superior anti-erosion performance when compared to other widely used equipment metals. The erosion profile agrees well with the shape of surface velocity distribution, indicating a close relationship between surface erosion behaviour and flow characteristics. In particular, the erosion pattern at a normal angle appears as a symmetric ring due to the flow stagnation phenomenon, with slight erosion damage in the centre area and severe erosion in the surrounding, whereas the erosion profile at an oblique angle displays an elliptic shape, with severe erosion damage in centre. Notably, the primary erosion mechanism varies dramatically in different surface regions, induced by the various impact velocities and angles associated with the corresponding changes in the flow field. This study provides a deeper understanding of erosion behaviour in terms of the interrelationship among the material mechanical properties, particulate flow field and particle-surface impingement behaviour.

Laboratory Model Tests on the Deformation and Failure of Terraced Loess Slopes Induced by Extreme Rainfall

Heavy rainfall is the main factor inducing the failure of loess slopes. However, the failure mechanism and mode of terraced loess slopes under heavy rainfall have not been well investigated and understood. This paper presents the experimental study on the deformation and failure of terraced loess slopes with different gradients under extreme rainfall conditions. The deformation and failure processes of the slope and the migration of the wetting front within the slope during rainfall were captured by the digital cameras installed on the top and side of the test box. In addition, the mechanical and hydrological responses of the slope, including earth pressure, water content, pore water pressure, and matric suction, were monitored and analyzed under rainfall infiltration and erosion. The experimental study shows that the deformation and failure of terraced loess slopes under heavy rainfall conditions exhibit the characteristic of progressive erosion damage. In general, the steeper the slope, the more severe the deformation and failure, and the shorter the time required for erosion failure. The data obtained from sensors embedded in the slope can reflect the mechanical and hydraulic characteristics of the slope in response to rainfall. The earth pressure and pore water pressure in the slope exhibit a fluctuating pattern with continued rainfall. The failure mode of terraced loess slopes under extreme rainfall can be summarized into five stages: erosion of slope surface and formation of small gullies and cracks, expansion of gullies and cracks along the slope surface, widening and deepening of gullies, local collapse and flow-slip of the slope, and large-scale collapse of the slope. The findings can provide preliminary data references for researchers to better understand the failure characteristics of terraced loess slopes under extreme rainfall and to further validate the results of numerical simulations and analytical solutions.

Numerical analysis of gas-solid flow erosion in different geometries as alternatives to a standard pipe elbow

This study was conducted with the aim of replacing different geometric fittings instead of the standard 90° elbow and trying to change the flow pattern to reduce erosion damage. Among fittings, the elbows are at a more serious risk. Numerical investigation of the present erosion with the novelty of research on non-spherical particles and changes in the impact angle of particles along with fluid flow using eight new proposed fittings, including two miter fittings, three blinded fittings, one reducer elbow fitting, and two spherical elbows fittings in comparison with the standard 90° elbow was controlled. The numerical simulation of the gas-solid two-phase flow of non-spherical particles was studied using the Euler-Lagrange approach. To carry out the study numerical, first, the gas flow was modeled by the Navier-Stokes equations and the turbulent Reynolds stress model, and then the solid particles were injected using Newton's equation. Finally, the erosion was calculated using Grant and Tabakoff model of the restitution of particles of after hitting the wall and the erosion model of Oka. The amount of erosion caused by changes in the flow pattern was investigated to evaluate the performance of the new proposed fittings. Numerical results for the most critical mode (Vin = 27 m/s and DP = 300 μm) showed that the new proposed fittings increase the erosion resistance by 22.5 % to 39.6 % compared to the standard 90° elbow. Also, in this research, the effect of different parameters including flow velocity, particle diameter size, particle input rate, and particle rotation on erosion were investigated.

Relationship Between Early and Established Rheumatoid Arthritis Vascular Change of the Dorsalis Pedis Artery Observed with Ultrasound Imaging

BackgroundDespite early treatment of rheumatoid arthritis (RA) being well established to prevent erosive joint damage, studies report persistent moderate to high disease activity. Other pathologies, for example, rheumatoid vasculitis (RV) may contribute symptoms that may not be captured by existing clinical assessment. ObjectivesTo investigate ultrasound-observed changes in the proximal dorsalis pedis artery (DPA) between early (≤ 5 y) and established (>5 y) RA and the RA Disease Activity Index-5 (RADAI-5). MethodsParticipants with early (n = 20) and established RA (n = 20) were recruited. Five parameters of the DPA were examined with a previously established ultrasound method. Independent t-tests and Cohen d statistics assessed differences and effect size between ultrasound parameters and RADAI-5, and the two groups. Pearson correlation assessed associations between ultrasound parameters and RADAI-5. ResultsMajority of participants (98%) demonstrated arterial wall thickening regardless of disease duration. However, lumen diameter (Cohen's d = 0.972, p = 0.004) and artery diameter (Cohen's d = 0.694, p = 0.034) were decreased in established RA compared to early RA. No strong associations were found between RADAI-5 and ultrasound parameters, except for lumen diameter in early RA demonstrating a fair association to RADAI-5 (r = 0.445). The mean RADAI-5 score indicated moderate to high disease activity with no difference between early and established RA (p = 0.283). ConclusionArterial wall thickening of the DPA indicating the precursory changes of RV was observed in most RA participants, with reductions in artery and lumen diameter occurring in established disease. However, the long-standing instrument RADAI-5 may not reflect symptoms and clinical impacts related to vascular changes among people with RA.

Changes at Presentation in Patients With Early Rheumatoid Arthritis: A 24-Year Study of the Early Undifferentiated Polyarthritis (EUPA) Cohort.

To analyze changes in baseline characteristics of patients with very early rheumatoid arthritis (RA) over 24 years in the Early Undifferentiated Polyarthritis (EUPA) cohort. Consecutive patients with recent-onset polyarthritis fulfilling RA classification criteria recruited in EUPA were assessed at baseline. Three successive periods were defined: (1) prior to the general availability of biologics (1998-2004; 245 patients), (2) prior to the implantation of the 2010 classification criteria (2005-2010; 266 patients), and (3) the most recent decade (2011-2022; 329 patients). At baseline, demographics, BMI, swollen and tender joint counts, proportion fulfilling 2010 American College of Rheumatology/European Alliance of Associations for Rheumatology criteria, modified Health Assessment Questionnaire, shared epitope status, patient-reported outcomes except pain, and patient global assessment of disease activity remained stable over the 3 periods. Despite a marked decrease in active smoking (22.2% to 12.1%), prevalence of cardiovascular comorbidities and prior cancer increased. Although duration of symptoms increased from a median of 2.9 to 4.1 months, decreases were seen in seropositivity (53.9% to 42.2%) and C-reactive protein beginning in the 2005-2010 period. A large decrease in erosive status (Sharp/van der Heijde erosion score ≥ 5; 18.3% to 9.4%) was only observed after 2011; this decrease occurred mostly in seronegative patients. Use of disease-modifying antirheumatic drugs prior to inclusion remained low and stable (25.7%), but use of oral corticosteroids increased (18% to 33.4%). Baseline characteristics of patients with RA evolved since 2005 toward less seropositivity and lower blood inflammation but with more comorbidities. Milder erosive damage at baseline became evident only since 2011, mostly in seronegative patients. These changes at baseline, before any intervention, suggest ongoing secular trends that may favorably affect outcomes in patients with early RA.

Failure analysis of erosion wear of the pipeline after 30° elbow by adsorbent particles

An adsorbent transport pipeline after a 30° elbow experienced premature perforation and leakage during service. The failure analysis was performed by means of morphology observation, damaged surface analysis and computational fluid dynamics (CFD) simulation. The results revealed that thickness thinning occurred only on the upper wall, and the severely thinned region exhibited a special striated groove morphology. The main cause of pipeline failure was attributed to erosive wear caused by adsorbent impacts on the wall. Due to the particle redistribution process under the action of multiple force fields in the small bending angle elbow, the straight pipeline after the elbow had a very complex inlet boundary condition, so that the particle concentration at the upper wall was substantially increased. Besides, the sliding motion of the particles on the wall surface was greatly intensified. Cutting deformation became the main form of erosion damage, which induced an alteration in the erosional morphology of the failed pipeline and the backwardness of the leakage site.

Magnitude and hotspots of soil erosion types during heavy rainstorm events on the Loess Plateau: Implications for watershed management

In the context of climate change, rainstorm events are becoming increasingly frequent. In particular, on the Loess Plateau, heavy rainstorms are the primary cause of soil erosion. This study investigated and analysed different types of soil erosion hotspots and influencing factors in small watersheds under different rainstorm events in different areas of the Loess Plateau. The results indicate that the erosion intensities of rills, gullies, landslides and collapses ranged from 13600-46244, 1982-772201, 1163-172153 t km-2 and 1867-94985 t km-2, respectively. Newly constructed terraces exhibited an erosion intensity 1.6 times greater than that of old terraces, while terraces constructed before the rainy season in the current year exhibited an erosion damage intensity 2.6 times greater than that of terraces constructed after the rainy season in the previous year. In addition, under rainstorm conditions, landslides represented the most severe type of erosion in the watersheds, with the maximum amount of erosion accounting for more than 90 % of the total erosion amount, followed by gully or collapse erosion, with the collapse of terrace risers as the main contributor. Slope cultivation land, unpaved roads, terrace risers, and valley slopes below the gully shoulder line were identified as erosion hotspot areas. Rainstorm erosion was significantly influenced by the land use type and slope, which explained 14.2 %-41.5 % and 9.7 %-15.1 %, respectively, of the total variance in erosion intensity. We suggest that soil erosion prevention and control efforts on the Loess Plateau should focus on landslides on valley slopes below gully shoulder lines, followed by gullies on unpaved roads and the collapse of terraced fields. Drainage ditches and water cellars should be constructed above the gully shoulder line and on the inside of roads and terraces, thereby reducing erosion. Our research is crucial for optimizing and adjusting watershed management measures and preventing rainstorm erosion disasters.

Hydrological Connectivity Response of Typical Soil and Water Conservation Measures Based on SIMulated Water Erosion Model: A Case Study of Tongshuang Watershed in the Black Soil Region of Northeast China

The black soil region of Northeast China is the largest commercial grain production base in China, accounting for about 25% of the total in China. In this region, the water erosion is prominent, which seriously threatens China’s food security. It is of great significance to effectively identify the erosion-prone points for the prevention and control of soil erosion on the slope of the black soil region in Northeast China. This article takes the Tongshuang small watershed (Heilongjiang Province in China) as an example, which is dominated by hilly landforms with mainly black soil and terraces planted with corn and soybeans. Based on the 2.5 cm resolution Digital Elevation Model (DEM) reconstructed by unmanned aerial vehicles (UAVs), we explore the optimal resolution for hydrological simulation research on sloping farmland in the black soil region of Northeast China and explore the critical water depth at which erosion damage occurs in ridges on this basis. The results show that the following: (1) Compared with the 2 m resolution DEM, the interpretation accuracy of field roads, wasteland, damaged points, ridges and cultivated land at the 0.2 m resolution is increased by 4.55–27.94%, which is the best resolution in the study region. (2) When the water depth is between 0.335 and 0.359 m, there is a potential erosion risk of ridges. When the average water depth per unit length is between 0.0040 and 0.0045, the ridge is in the critical range for its breaking, and when the average water depth per unit length is less than the critical range, ridge erosion damage occurs. (3) When local erosion damage occurs, the connectivity will change abruptly, and the remarkable change in the index of connectivity (IC) can provide a reference for predicting erosion damage.

Computational Fluid Dynamics Study on Bottom-Hole Multiphase Flow Fields Formed by Polycrystalline Diamond Compact Drill Bits in Foam Drilling

High-temperature geothermal wells frequently employ foam drilling fluids and Polycrystalline Diamond Compact (PDC) drill bits. Understanding the bottom-hole flow field of PDC drill bits in foam drilling is essential for accurately analyzing their hydraulic structure design. Based on computational fluid dynamics (CFD) and multiphase flow theory, this paper establishes a numerical simulation technique for gas-liquid-solid multiphase flow in foam drilling with PDC drill bits, combined with a qualitative and quantitative hydraulic structure evaluation method. This method is applied to simulate the bottom-hole flow field of a six-blade PDC drill bit. The results show that the flow velocity of the air phase in foam drilling fluid is generally higher than that of the water phase. Some blades’ cutting teeth exhibit poor cleaning and cooling effects, with individual cutting teeth showing signs of erosion damage and cuttings cross-flow between channels. To address these issues, optimizing the nozzle spray angle and channel design is necessary to improve hydraulic energy distribution, enhance drilling efficiency, and extend drill bit life. This study provides new ideas and methods for developing geothermal drilling technology in the numerical simulation of a gas-liquid-solid three-phase flow field. Additionally, the combined qualitative and quantitative evaluation method offers new insights and approaches for research and practice in drilling engineering.

Preparation of protective coatings for the leading edge of wind turbine blades and investigation of their water droplet erosion behavior

The damage caused by rain droplet erosion to the leading edge of wind turbine blades is extremely severe. To reduce this issue, in this study, hydroxyl-terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI) were used as the polyurethane (PU) polyol and curing agent, respectively, to prepare a PU coating with a high resistance to water droplet erosion (WDE) for the protection of the leading edge of wind turbine blades. The effect of n (–NCO):n (–OH) (R-value, n is the molar ratio) on the mechanical properties and WDE resistance of PU coatings, the relationship between the two performances, and the influence of the erosion conditions on the WDE behavior were investigated for the first time. The results show the existence of a correlation between the mechanical properties (hardness, impact, flexibility, and tensile strength) and WDE resistance of the coating. While, a better abrasion resistance is found not to result in a better WDE resistance. The PU coating with an R-value of 1.2 shows an optimal WDE resistance in both atomization and jet erosion experiments. In atomized droplet erosion (ADE) experiments, the change in erosion velocity accelerates the incubation period of coating erosion damage and increases the erosion rate. In jet droplet erosion (JDE) experiments, the damage to the coating is closely related to the erosion angle, reaching a maximum at an impact angle of 60°. Furthermore, in the ADE experiments, various erosion morphologies, such as pits, grooves, cracks, and stepped texture, are observed on the damaged coating surface. While, regarding the JDE experiments, holes, grooves, and cracks are observed. Such damage is caused by the combined effects of water hammer pressure, lateral jets, and local permeation.

A numerical study of volcanic ash ingestion and erosion of the front components of a high bypass turbofan engine

Abstract Airborne particles, such as dust and volcanic ash, pose a serious hazard to aircraft in flight due to their potential to cause erosion damage to engine components. It is crucial to anticipate and address the impact of erosion wear on engine performance and safety. This study aims to enhance our understanding of how volcanic ash particles behave when ingested through a high bypass turbofan engine (HBTFE) and assess the development of erosion wear in the front components. The effects of four different ash samples are assessed in various scenarios of encountering volcanic ash during cruise flight conditions. First, the flow solution is obtained for all front components, including the Pitot intake, spinner, fan, inlet guide vanes (IGVs), outlet guide vanes (OGVs), and connecting ducts. Based on the flow data, the particle motion equations are solved step by step using an in-house trajectory and erosion code. This latter adopts the Lagrangian approach, which incorporates a particle-eddy interaction model and includes probabilistic descriptions for the release positions of particles, sizes, and restitution factors. The finite element method (FEM) is used to track particles through the computational cells and determine impact positions and conditions. As a result, the Pitot intake design seems to prevent many ash particles from reaching the fan blade beyond 80% of the span. The fan blade leading edge (LE) exhibits extreme erosion on both sides. The blade’s pressure side (PS) displays erosion spreading practically on the entirety of the surface, especially near the trailing edge (TE). In contrast, the suction side (SS) has scattered erosion at lower rates. Furthermore, the rotor’s hub presents almost uniform erosion patterns, whereas the shroud depicts scattered erosion. This large fan appears to function as a separator, expelling a significant amount of ash particles through the secondary duct, thereby reducing the engine core’s susceptibility to erosion. Out of the four volcanic ash samples, those from the Kelud and Etna volcanoes appear to cause the highest hourly eroded mass, about twice as much as the samples from the Chaiten and Eyjafjallajokull volcanoes.

Experimental research of corroded concrete beams with natural cooling after fire considering the bond deterioration

The residual bearing capacity after fire is of great significance for safety assessment and repair of building structures. To accurately evaluate the residual strength of corroded beam after natural cooling, this study investigated the residual bearing capacity of corroded beam considering the bond deterioration after fire exposure. First, the bond behavior and flexural-deformation capacity was conducted by pullout test and bending test after corrosion erosion and fire temperatures damage. The bond deterioration test shows that when the temperature rises above 200℃ and the corrosion level exceeds 4.3%, the bond strength decreases by 16.5%. At the temperature reaches 600℃ or the corrosion degree reaches 13.8%, the bond behavior damage exceeds 50%. The bending test indicates that corrosion and high temperature damage both decrease the bending bearing capacity of the beam, but the influence of high temperature damage on the residual bearing capacity is greater than that of corrosion. The bond property deterioration decreases the strain value of the tensile rebar during the bending process, and decreases the bending capacity of the beam. Finally, a bond-slip constitutive model suitable for corroded beams after fire is proposed, which is applied to the calculation of the ultimate moment of the beam. The modified value of beam bearing capacity considering bond deterioration has better collimation and higher safety margin. The bond-slip constitutive model and the modified calculation method of bending moment of beam are helpful to provide more accurate performance assessment of beam after the coupling effect of corrosion and fire damage.

Establishment of an Animal Model of Oral Squamous Cell Carcinoma Invading the Mandible.

To establish an animal model of oral squamous cell carcinoma invading the mandible through multi-sample experiments that verified the stability, repeatability, tumorigenicity and mandible destruction rate of the model. Oral squamous cell carcinoma cell suspension was injected into the outer side of the mandible through the anterior edge of the masseter muscle of naked mice to observe the tumourforming process. Then, the anatomical, histological and imaging examinations were carried out to determine whether the tumour had invaded the mandible. By comparing the tumour growth of multiple groups of various squamous cell carcinoma cells (CAL27, HN6 and HN30 cells), the changes in body weight and characteristics of tumour formation were compared, and the experience was summarised to further verify the stability, repeatability, tumour formation rate and arch damage rate of the model. The subsequent specimens of tumour-bearing nude mice were validated once the model had been established. In vitro, tumour tissue wrapped around the mandible's tumour-bearing side, and the local texture was tough with no resistance to acupuncture. Haematoxylin and eosin staining revealed that squamous cells were infiltrating the mandible in both the horizontal and sagittal planes. Microcomputed tomography results showed that the mandible on the tumour-bearing side displayed obvious erosion damage. Cell lines with various passage rates clearly had diverse tumour-bearing life cycles. This study successfully established an animal model of oral squamous cell carcinoma invasion of the mandible. The model has excellent biological stability, repeatability, tumorigenesis rate and mandible destruction rate.

Machine Learning for Dynamic Pressure Coefficient Prediction in Vertical Water Jets

Vertical water jets present significant challenges for hydraulic structures due to their potential to cause erosion and structural damage. This study aimed to predict the dimensionless pressure coefficient (Cp) of vertical water jets by examining the relationships between experimental parameters, such as Froude number, slope, and the ratio of waterfall height over the product of the Froude number and diameter, referred to as α, using machine learning models. Two hundred forty controlled experiments were conducted, with pressure data collected. To address the problem’s non-linearity, six machine learning models were tested: linear regression, K-nearest neighbors, decision tree, support vector regression, random forest, and XGBoost. The XGBoost model outperformed others, achieving an R-squared of 0.953 and a Root Mean Squared Error (RMSE) of 0.191. Residual analysis validated its better performance, demonstrating that it delivered the most accurate predictions with minimal bias. Feature importance analysis revealed the Froude number was the most significant predictor, followed by slope and diameter. This study emphasizes the importance of the Froude number in predicting jet behavior and shows the efficacy of advanced machine learning models in capturing complex fluid dynamics, providing valuable insights for optimizing engineering applications such as water jet cutting and cooling systems.

Integrating TiNx to Fe-based amorphous coating by reactive plasma spray for ameliorating multi-scale mechanical behavior and corrosion-abrasion resistance

Ocean engineering components are subjected to intense corrosion and abrasion. To address these challenges, the Fe-based amorphous composite coating was engineered for compatibility with these harsh conditions. The Fe-based amorphous composite coating, incorporating TiNx, demonstrated improved nanomechanical properties, offering enhanced resistance against external forces. The integration of TiNx acted as a structural backbone, limiting crack propagation within the amorphous matrix. Although the corrosion resistance of this composite coating was slightly reduced, it demonstrated improved durability subjected to hydraulic machinery corrosion abrasion working condition. Notably, under conditions of higher tribological pair speeds and increased sand concentrations, this composite coating exhibited significantly lower weight loss increase and reduced wear rates escalation compared to coatings made entirely from Fe-based amorphous material. Moreover, the composite coating exhibited diminished susceptibility to erosion damage, with reduced size and severity of erosion craters. These underlying mechanisms are thoroughly discussed in the paper.

Passive flow control of a Francis turbine operating in sand-laden rivers for mitigating sediment erosion

In a typical Francis turbine operating in sand-laden rivers, owing to its complicated geometry and variable operating conditions, vortex structures appear and cause severe erosion damage to turbine components. Here, we present a bioinspired method to mitigate severe sediment erosion on Francis turbines. The proposed method includes a passive flow control strategy using biomimetic convex domes for the inter-blade vortex, a major contributor to severe sediment erosion on the turbine runner. The effects of biomimetic convex domes on sediment erosion are investigated through numerical simulations and experiments. The results indicate that biomimetic convex domes significantly reduce the impact velocity and accretion rate of the particles, eventually reducing sediment erosion by at least 50 %. The mechanism underlying the effect of convex domes on sediment erosion is their inhibition of the development of the inter-blade vortex. The convex domes induce small-scale vortices from the blade boundary layer. When located in the nascent region of the inter-blade vortex, the small-scale vortex effectively inhibits its formation. Moreover, convex domes placed in severe erosion areas can accelerate the dissipation process of the inter-blade vortex.