Concave Surface Research Articles

Runoff generation and erosion processes at the rock–soil interface of outcrops with a concave surface in a rocky desertification area

Rock surface flow, originating from outcrop surfaces during rainfall, represents a distinctive form of runoff influencing surface erosion and subsurface soil leakage in karst rocky desertification areas. Despite their significance, the processes governing runoff generation and erosion at the rock–soil interface (RSI) under the influence of rock surface flow remain poorly understood. This study aims to elucidate the generation and transformation of runoff at the RSI, along with their scouring erosion effects influenced by rock surface flow from concave-shaped outcrops. Artificial rainfall experiments were conducted on simulated rock–soil structural units featuring exposed rock surfaces and unexposed RSIs of outcrops with concave shapes. Two driving factors, namely rainfall intensity (R) and the inclination of the rock surface (IRS), were manipulated to investigate the formation and output processes of runoffs and sediments from the surface, RSI, and non-RSI (a site away from the RSI). The presence of an exposed rock surface altered the distribution pattern of rainfall–infiltration–runoff. An increase in the IRS led to a significant decrease in surface runoff (p < 0.05). When the IRS was close to vertical, the rainfall-runoff was primarily in the form of surface runoff; however, for inclinations less than 90°, the primary contributors to rainfall-runoff were the RSI and non-RSI runoffs. Surface soil erosion emerged as the predominant form of soil loss, with runoff yield demonstrating a linear positive correlation with sediment production. Both the IRS and R were identified as significant factors affecting surface runoff and soil erosion. Notably, when the IRS was less than 45°, the total soil loss reached its minimum. Therefore, runoff generation at the RSI led to a reduction in surface runoff and an increase in subsurface runoff, contributing to soil leakage at the RSI. Nevertheless, surface erosion remained the primary mechanism of soil loss.

Mechanism of Membrane Curvature Induced by SNX1: Insights from Molecular Dynamics Simulations.

SNX proteins have been found to induce membrane remodeling to facilitate the generation of transport carriers in endosomal pathways. However, the molecular mechanism of membrane bending and the role of lipids in the bending process remain elusive. Here, we conducted coarse-grained molecular dynamics simulations to investigate the role of the three structural modules (PX, BAR, and AH) of SNX1 and the PI3P lipids in membrane deformation. We observed that the presence of all three domains is essential for SNX1 to achieve a stable membrane deformation. BAR is capable of remodeling the membrane through the charged residues on its concave surface, but it requires PX and AH to establish stable membrane binding. AH penetrates into the lipid membrane, thereby promoting the induction of membrane curvature; however, it is inadequate on its own to maintain membrane bending. PI3P lipids are also indispensable for membrane remodeling, as they play a dominant role in the interactions of lipids with the BAR domain. Our results enhance the comprehension of the molecular mechanism underlying SNX1-induced membrane curvature and help future studies of curvature-inducing proteins.

Influence of wall curvature on evolution of converged flow generated by crossing shock wave/boundary layer interaction: An experimental study

The curved surfaces widely exist in three-dimensional inward-turning inlets and variable sectional isolators, which determine the downstream evolution of the converged flow generated by the crossing shock wave/boundary layer interaction, thereby affecting the start performance and combustion efficiency of the hypersonic vehicles. In this work, the converged flow subjected to the curved surfaces is experimentally studied with the nanoparticle-based planar laser scattering method and particle image velocimetry. Results show that the velocity profiles of the converged flow on the transverse plane can be normalized at different angles. The upstream separation size is found to be decreased by the downstream convex surface due to the reduction of backpressure, especially in large-radius cases, whereas the converged flow gradually becomes smooth ought to the dependence of the acceleration effect on the velocity. The concave surface shows an opposite effect on the converged flow, which further indicates that a downstream convex surface is preferred for hypersonic inlets to weakens the flow non-uniformity to improve the inlet performance.

Analysis of machined surface quality for multi-feature standard parts

Analyzing the machined surface quality of a multi-feature part helps to find out a comprehensive solution for machining quality promotion for complex multi-feature products. It is also significant to detect the machining accuracy and performance of the machine tools. In this paper, the surface of a standard part is adopted to investigate multi-feature part machining application, which has more than 5 types of features, such as plane, bevel, curved, cylindrical, etc. Three groups of finish machining experiments with different parameters are firstly conducted to conclude the effect of features on the machined surfaces. Then, surface roughness and morphology were measured and compared for five features under the same machining parameters to reveal machined quality differences between surfaces. The effects of inclination angle and curvature on the surface quality are also theoretically analyzed. It is found that the contact area between the tool and the part varies with the inclination angle of the bevel, leading to different roughness variations. Between the plane and curved surfaces, the concave surface has the highest roughness, while the convex surface has the lowest. Moreover, the wear of four tools with different machining time is examined. It is shown that, with the increase of machining time, the tool tip wears more severely than the rake and the flank. Furthermore, the correlation between tool wear and surface roughness is also studied by regression analysis, which confirms that the quality difference of some surfaces is related to the tool wear state.

Design and Mechanical Properties of Maximum Bulk Modulus Microstructures Based on a Smooth Topology with Grid Point Density

The aim of topology optimisation is to determine the optimal distribution of material phases within the periodic cells of a microstructure. In this paper, the density of grid points under element volume fraction is constructed to replace the finite elements in the traditional SIMP framework, avoiding jagged and blurry boundaries in the computational process due to grid dependence. This is then combined with homogenisation theory, a microstructure topology optimisation algorithm with maximum bulk modulus under prescribed volume constraints is proposed, which can obtain 2D and 3D topologies with smooth boundaries. In addition, a closed form expression for the two-dimensional topological concave edge structure (taking the most typical topology as an example) was derived, and a compression experiment was conducted on the topological microstructure based on 3D metal printing technology. Scanning electron microscopy showed that the powder bonded on the surface of the printed structure was not completely melted and the step effect caused the finite element analysis results to be higher than the experimental results. Overall, the finite element simulation and experimental results of the concave surface structure have good consistency, with high strength and energy absorption effects. Topologies based on grid point density obtain microstructures with smooth boundaries, and the introduction of the Heaviside smoothing function and multiple filtering steps within this algorithm leads to more robust optimisation, facilitating 3D or 4D printing of microstructures that meet specific design requirements and confirming the feasibility of the proposed topology for lightweighting studies.

Preparation and properties of bimetallic Co/Cu ZIF-67 for electrochemical application

Efforts to enhance the electrochemical properties of materials have become the focus of numerous studies because these properties are essential in various fields of application. Zeolitic imidazole framework-67 (ZIF-67) is a type of metal-organic framework (MOFs) expected to demonstrate excellent performance in electrochemical applications due to its numerous distinct properties. Consequently, various strategies and techniques have been developed to improve the electrochemical performance of ZIF-67. In this study, we employed bimetallic ZIF-67 constructed with cobalt (Co) and copper (Cu) metal ions within the imidazole frameworks. The use of bimetal is expected to increase conductivity and fine-tune the physicochemical properties of ZIF-67. Using coprecipitation methods, we synthesized both single-metal and bimetallic ZIF-67 and compared their characterizations. The addition of Cu metal ions does not alter the materials phase, ensuring compatibility with the single-metal ZIF-67 structure. However, the rhombic dodecahedron morphology of ZIF-67 shifts from a smooth to a concave and rough surface in Co/Cu ZIF-67. Furthermore, Co/Cu ZIF-67 exhibits higher peak current on their cyclic voltammetry (CV) curve by 46.15 µA. The results effectively illustrate the advantages of bimetal on ZIF-67 properties and performance. Finally, this study succesfully briefly demonstrate the potential development of Co/Cu-based ZIF-67 for various electrochemical applications.

Phase Correction of the Channels of a Fully Populated Randomized Multielement Therapeutic Array Using the Acoustic Holography Method

The acoustic holography method was used to characterize a therapeutic focused fully populated 256-element ultrasonic transducer array. Elements of the array with the shape of equal area polygons are densely arranged in an irregular pattern on a spherically concave surface with a radius of curvature of 150 mm and a diameter of 200 mm. The array has a central frequency of 1.2 MHz and is designed to operate in water. The performance of individual array elements was studied based on the holographically reconstructed normal velocity distribution over the array surface. It was shown that with the same electrical signals applied to the elements, their acoustic responses had a phase deviation relative to the nominal values, which can be caused either by the asphericity of the array surface, or by the introduction of additional phase delays by the electrical matching network. To compensate for the detected parasitic phase shifts of the elements and restore the effective sphericity of the radiating surface, the Verasonics V-1 control system was used. The hologram measured after making the correction, as well as the shape of the focal region and acoustic pressure magnitude at the focus, separately measured by a hydrophone, showed that the proposed method reconstructed the nominal operating parameters of the array with high accuracy.

Surface quality enhancement by constant scallop-height in three-axis milling operations

The quality of machined part surfaces are under the impact of scallop height which should be analyzed and minimized. Achieving a uniform scallop-height is important for ensuring a smooth surface finish and maintaining consistent material removal across the machined surfaces during CNC machining operations. This approach helps to reduce material waste, tool wear and part production errors while ensuring consistent and high-quality of machined parts. Maintaining a constant scallop height can also help to reduce chatter and vibration during milling operations. The research work develops a virtual machining methodology to produce constant scallops through three-axis milling operations. The proposed approach examines free-form surfaces of workpiece in order to obtain free form surfaces curvatures. Then, free-form surfaces are separated into flat, convex and concave surfaces to provide optimized cutting tool variables in order to provide constant scallop height during CNC cutting tool paths. Achieving a constant scallop height involves optimizing cutting parameters such as feed rate, spindle speed, and step over. To calculate the optimized machining parameters of feed rate, speed of spindle and step over, the Taguchi optimization methodology is utilized in the study. Then, the machining variables of feed rate, speed of spindle and step over are optimized to achieve the uniform scallop height during milling potations of free-form surfaces. As a result, using optimized machining parameters during machining operations, the surface roughness of machined components are reduced by 23.8%. So, the proposed virtual machining method can enhance surface quality of machined parts during CNC milling operations of free-from-surfaces.

A Case of Proliferative and Necrotizing Otitis Externa in a Scottish Fold Shorthair Cat

In this case report, the aim was to contribute to understanding PNOE's clinical presentation, histopathological features, and successful treatment approaches, emphasizing the significance of accurate diagnosis and appropriate management in affected felines. Proliferative necrotic otitis externa (PNOE) is a very rare skin disease of unknown etiology affecting the vertical ear canal and the concave surface of the auricle, which may be accompanied by secondary yeast or bacterial infections. In this case 8-month-old Scottish fold shorthair cat has fragile, papillomatous growths and caseous purulent exudate in the ear canal was presented. The differential diagnosis of this condition includes otoacariasis, plasma cell pododermatitis, papillomavirus and chronic bacterial or yeast otitis externa. Despite antimicrobial and antiparasitic based previous treatments, the lesions persisted. Histopathological examination revealed acanthotic epidermis, necrotic keratinocytes, and inflammatory cell infiltrates. Treatment involved methylprednisolone injection, topical pomades, and systemic antibiotics. The cat showed improvement after initial treatment week, with regression of lesions and cessation of ear discharge. Follow-up visits demonstrated continued improvement, and after two months, minimal sequelae remained. In conclusion, despite the unknown etiology of PNOE, the disease is quite responsive to immunosuppressive therapy, which is beneficial for both diagnosis and treatment.

The mechanical characteristics and cooling performance of a turbine blade with non-homogeneous lattice structure

The turbine blade is working at a high rotation speed and under constant impact from the high-temperature and high-pressure mainstream, causing deformation and a reduction in working efficiency; at the same time, the mainstream temperature at the inlet is increasing to achieve a high heat efficiency. Therefore, there is a high demand for turbine blade cooling technology. In this study, the authors proposed replacing the traditional spoiler with a non-homogeneous lattice structure in the inner cavity of the high-pressure turbine blade. The turbine blade was then simulated and experimend in real-world conditions using numerical simulation software and manufactured actual blades, and the maximum deformation of the turbine blade was measured to assess the impact of the non-homogeneous lattice structure on the blade's strength. The findings are as follows: The maximum deformation of the turbine blade optimized with a non-homogeneous lattice structure is 9.91% less than that of the traditional turbine blade with a spoiler, and its deformation-weight ratio is 11.51% less than the latter; the optimized turbine blade has a large cooling area in the concave surface of the blade, which improves the air film cooling effect, the coverage area of gas film hole outlet flow rate has increased by 12.39%. Finally, the non-homogeneous lattice structure optimizes the inner cavity structure of the turbine blade and is useful for improving the turbine blade's structural design and air film cooling performance.

Effect of truncated pin-fins on flow and heat transfer characteristics with impinging jets on a concave surface

The double-wall cooling system containing jet impingement and full-length pin-in cooling structures shows good performance in heat transfer enhancement and uniformity, which has-been used in the blade cooling design. However, the pressure loss induced by the full-length pin-fin is relatively high. It is very meaningful to get a cooling type which can balance the heat transfer performance of double-wall cooling and flow resistance, especially for the blade leading edge. In this study, numerical simulations have been carried out to study the influences of truncated pin-fins height and arrangement on heat transfer increment and flow behavior of jets impinging onto a concave double wall channel with varying truncated pin-fins arranged, considering the heat transfer enhancement potential and relatively weaken pressure loss penalty of truncated/broken pin-fin. Jets impingement on a smooth-concave surface is regarded as Baseline. Streamlines in two-dimensional sections in the channel and limiting streamlines near the target wall conjugated with flow characteristics figures are applied to better understand the flow structures in the channel. The local and averaged heat transfer performance is analyzed based on the flow discussions. The overall parameters, i.e., thermal performance, friction factor and pumping power, are also obtained. The results show that the introduction of relatively high truncated pin-fins located on the upper wall presents higher heat transfer enhancement and lower pressure loss comparing with the full-length case and truncated pin-fins located on pressure loss comparing with the full-length case and truncated pin-fins located on target wall cases. The truncated pin-fins placed on the upper surface with relative height of 0.75 reaches the highest overall thermal performance and uniformity in this work.

Centrifuge and analytical modeling of counterweight retaining walls under translation mode

Counterweight retaining walls (CRWs) are a variant of gravity-retaining walls that feature a pressure relief platform (RP) on the backfill side to reduce total earth pressure, offering a cost-effective option compared to traditional forms. However, the intricate interactions between CRWs and backfill, coupled with the lack of clear design guidelines, have restricted their use. This study examines the behavior of CRWs in translation mode using three different centrifuge model tests, each with varying fill heights. Observations show a slightly concave slip surface through the wall heel and a nearly planar slip surface extending from the edge of the RP to the back of the wall in an active limit state. Backfill movement can be classified into translation, sliding, and stable zones. Earth pressure distribution on the upper wall follows a trapezoidal pattern, whereas the pressure on the lower wall exhibits a triangular distribution. Earth pressure on the RP is approximately linear, peaking near the RP’s edge. Introducing a friction angle mobilization factor for the potential first slip surface improves accuracy in calculating earth pressure. The tests were replicated to validate the analytical model for earth pressure calculations, using the adaptive finite-element limit analysis method.

Parabolic concave surface modified by carbonized micro-cone array on rattan enables multi-dimensional light harvest for bio-based solar evaporators

It is imperative to delve into multi-dimensional light harvest solution that enhance vapor production without increasing solar energy input. Herein, we demonstrate a rattan-based evaporator with parabolic concave surface modified by carbonized micro-cone array. The parabolic concave surface facilitates multiple reflections of light, which could exhibit peak evaporation ability under not vertically irradiated light. The carbonized micro-cone array not only multiply enlarges available evaporation area and promotes the full directional release of vapor, but also forms the Marangoni flow which drives a liquid circulation to facilitate salt reflux. The design of our evaporator achieve a evaporation rate of 2.06 kg·m−2·h−1 with 94.48 % energy conversion efficiency credited to 90.27 % light absorption owing to the distinctive and sophisticated surface. Simultaneously, this evaporator showcases stable performance for long-time use and achieves a commendable salt purification rate of 99.6 %. We harness the widespread grow rattan in potable-water-scarce regions/countries, forming an integration of complementary resources.

Ultrasonic measurement of fill volume of bulk solids in discharge vessels

In bulk solid handling, measuring the fill volume of vessels with powders is complex due to the uneven material surface. This research presents a method using an array of narrow-beam ultrasonic range finders in a powder discharge vessel. The vessel's cross-sectional area was divided into equal sub-sections, each measured by a range finder. The total fill volume was calculated by summing up the volumes of these sections. This system allows quick volume estimates at around 0.9 Hz under various flow states. In static conditions, tests on flat, concave, and convex powder surfaces showed a volume discrepancy of <5% of vessel capacity. For a vessel discharging polyethylene pellets, the estimated fill volume was under 0.6% uncertainty (confidence interval: 0.95). The findings underscore the utility of ultrasonic range finders for accurate volume determination in powder discharge vessels.

Enhancing the performance of Savonius rotor using tiered-height zigzag patterns in concave surface

A technique to reduce CO2 emissions from the use of fossil fuels is to use clean energy. One of them is wind energy, which is generated by a wind turbine. Savonius, a type of vertical axis wind turbine, is a small-scale energy conversion device suitable for low wind speeds, such as those characteristic of Indonesian wind speed. The objective of the current study was to analyze the impact of implementing a tiered-height zigzag pattern on the concave surface of the Savonius blade. The zigzag angle operates to direct the wind toward the reverse blade, consequently augmenting the pressure on the reverse blade. In addition, the tiered-height zigzag pattern in the concave surface increases the area of the turbine that is in contact with the wind, which in turn generates more energy. This study used an open-type wind tunnel to conduct experiments as the primary technique of investigation. Its performance was assessed in terms of power and torque coefficients. Additionally, experiments were conducted with other standard semi-circular blades to get a direct comparison. According to the findings of the experiments, incorporating a tiered-height zigzag pattern into a concave surface may produce a power coefficient (Cp) that is 16 % higher than that of a semi-circular. The highest Cp was 0.286 at a TSR of 0.55 and U = 6 m/s. In this case, the Savonius wind turbine's ability may be elevated by including a tiered-height zigzag pattern in the Savonius concave surface.

Волны Рэлея на гладкой кривой поверхности

A model has been developed that describes the propagation of surface waves on smooth curved surfaces. This model is developed using the hyperbolic wave equation and is applicable to studying the propagation of surface waves on any curved surface described by a related orthogonal curvilinear coordinate system and for any values of the product of the wave vector and the radius of curvature. The behavior of Rayleigh waves on canonical curved surfaces (cylinder, sphere) is simulated, and the results are used to quantify the effect of curvature on the speed of Rayleigh waves. The condition for the existence of a Rayleigh wave is the validity of the values of the wave vectors K obtained from the dispersion equations. The actual values of the wave vectors K determine the waves propagating along the surface without carrying the energy deep into the body. The speed of the surface wave increases with increasing curvature of the concave surface, and decreases on the concave surface. The Rayleigh wave has limited growth as the positive radius of curvature decreases. At positive values of the radius of curvature (outer surface), as the radius decreases, a maximum is observed, and then the speed of waves decreases and breaks of curves are observed at negative curvature (inner surface), which is associated with resonance along the circumference of the envelope of a cylinder or great circle of a sphere.

Strengthening of the railroad track for high-speed traffic on the Bukhara-Misken section

In the article the work of ballast prism and subgrade is considered, on the basis of analysis two-layer reinforcement from geotextile is offered, also strengthening by water-soluble polymer in conditions of sandy zone on high-speed sections of railroads is suggested. The principle of stationarity of the total potential energy of deformable Lagrangian systems is used to determine the stress-strain state of the earth bed. The dependences between the components of stress and strain tensors characterizing specific models of the medium have been established, and an elastic ground medium with no residual deformation from external load has been considered. And also offer designs of sleepers with concave surface, which will increase the service life and ensure the reliability of its operation on horizontal and vertical curves of railroads. A new fluoroplastic under-rail gasket, which does not change its characteristics during 5 years, contacting with the base of the rail, flat inner support surface, contacting with the sleeper, reduces load vibration from the rolling stock on the sections of high-speed traffic is offered.

Characteristic Differences between Freeze-dried Tenogenic Secretomes and Freeze-dried Crude Secretomes of Mesenchymal Stem Cells under Hypoxic Conditions

ABSTRACT Introduction: Tendons that are crucial for movement are struggling with self-healing. Regenerative medicine has been using mesenchymal stem cells (MSCs) and their secretomes, and it offers promise. These secretomes, rich in growth factors, aid tissue healing. Tenogenic secretomes target tendon-specific healing, while crude ones provide a broader view of MSC signaling. The study aims to enhance targeted interventions in tendon regeneration and improve the quality of life for those with tendon-related issues. Methods: This laboratory study compares freeze-dried tenogenic and crude secretomes of MSCs under hypoxic conditions for regenerative potential. Stem cells from adipose tissue undergo isolation, culture, and multiplication then treated in hypoxic conditions. Characterization, Interleukin-6 (IL-6) and Interleukin-10 (IL-10) analysis with enzyme-linked immunosorbent assay (ELISA) follow. The results, including organoleptic, pH, and scanning electron microscope assessments, were presented descriptively. Statistical analysis will enhance understanding. Results: Physical characteristics (odor, color, and pH) are similar in both groups. Tenogenic secretome has a more concave surface, potentially aiding cell migration compared to the crude secretome. There were significant differences in cytokine levels (P = 0.001). IL-6 levels expressed from tenogenic secretome were 10.2 ± 2.432 pg/mL compared to the crude one which 18.3 ± 3.175 pg/mL. Levels of IL-10 expressed from tenogenic and crude secretomes were 309.2 ± 50.973 pg/mL and 200.1 ± 32.030, respectively. Conclusion: The tenogenic secretome and crude secretome exhibit no differences in physical characteristics but differ in surface morphology. The concave surface of the tenogenic secretome facilitates cell migration more than the crude secretome. Under hypoxic conditions, the tenogenic secretome shows lower pro-inflammatory (IL-6) and higher anti-inflammatory (IL-10) effects than the crude secretome.

A non-null interferometry for concave aspheric surface

A non-null interferometry for concave aspheric surface

Characterization of Secondary Vortices in Supercritical CO&lt;sub&gt;2&lt;/sub&gt; Flow in a Channel Formed by a Concave Surface of a Pyramid

Characterization of Secondary Vortices in Supercritical CO&lt;sub&gt;2&lt;/sub&gt; Flow in a Channel Formed by a Concave Surface of a Pyramid