Size Of Ridges Research Articles

Intensifying interfacial oscillations in falling film flows over rectangular corrugations

Unsteady film flows play an important role in intensifying heat and mass transfer processes, with applications, e.g., in falling film absorbers or reactors. In this context, the influence of surface structure modification on the wave dynamics of falling film flows is experimentally investigated based on localized film thickness time series data. Arrays of rectangular ridges oriented perpendicular to the main flow direction are considered, and an optimum ridge distance is identified, at which particularly strong interfacial oscillations are induced in the falling film. These potentially result from the interaction of the flow with a statically deformed base film under resonance-like conditions. The transient destabilization is amplified in the case of narrow ridge sizes, where inertia-driven flow features are particularly pronounced. With regard to mass transfer applications, the structure-induced increase in gas–liquid interfacial area may be of secondary importance compared to changes in internal flow conditions.

Evaluation of Digitally Customized Titanium Mesh-Guided Alveolar Ridge Augmentation

Background: Different bone augmentation methods are used to increase the alveolar crest following the loss of one or more teeth. Guided bone regeneration is an alternative to increasing the amount of hard tissue for subsequent implant placement in the best three-dimensional position. Objectives: To evaluate the effects of bone regeneration utilizing a customized titanium mesh scaffold covered with a combination of autologous bone transplant and xenograft for the restoration of complex jaw deformities. Methods: This prospective clinical interventional study included ten patients receiving ridge augmentation of the partly edentulous mandible or maxilla after the alveolar ridge had resorbed (horizontally). A pre-surgical cone beam computed tomography (CBCT) scan was performed to assess the pre-surgical ridge size and fabricate the customized titanium mesh (CTM). A CBCT scan will be performed immediately after surgery, followed by a second CBCT scan 6 months later to measure width and volumetric analysis. Results: Both arches had a rise in volumetric gain from preoperative to postoperative, with no significant difference. Females gained more than males, although the difference was not statistically significant (males lost density after surgery). They also discovered that age, gender, and arch were not substantially associated with mesh size exposure. Conclusions: Using tailored titanium mesh scaffolds in conjunction with autogenous bone and xenografts for alveolar ridge augmentation can efficiently increase bone mass, but future research must address many limitations.

Discrete Element Method–Multibody Dynamics Coupling Simulation and Experiment of Rotary Tillage and Ridging Process for Chili Pepper Cultivation

Rotary tillage, ridging, and mulching are commonly used cultivation methods for crops such as chili peppers, tomatoes, and strawberries in the arid regions of Northwest China. An integrated machine for rotary tillage, ridging, and mulching was designed by considering the growth characteristics of pepper root systems and the agronomic requirements of ridge beds. The structural parameters and their value ranges for key components such as the rotary tillage device and the ridging device were determined. By introducing the Bonding contact parameter, the soil cohesion between soil particles during the process of rotary tillage and ridging can be simulated. A coupled simulation model using the Discrete Element Method (DEM) and Multibody Dynamics (MBD) is established. The experimental factors selected were rotary tillage depth, ridging roller speed, and machine forward speed. The evaluation indexes were the traction resistance of the stemming roller and the soil compactness of the ridges. A response surface Box–Behnken Design test was carried out to obtain the best working parameters of the rotary tillage and ridging process for chili pepper cultivation as follows: the rotary tillage depth was 176 mm, the ridging roller speed was 283.71 r/min, and the machine forward speed was 0.55 m/s. Field experiments with optimal parameters showed that the ridge top width was 549.2 mm, the ridge bottom width was 750.5 mm, the ridge height was 222.9 mm, the ridge spacing was 1173.1 mm, the surface smoothness of the ridge was 12.3 mm, the width of soil covering the film edge was 76.3 mm, the stability coefficients of the ridge size parameters were all above 91.73%, and the soil compactness after operation was 60.82 KPa. All indicators meet the requirements for the rotary tillage and ridging cultivation of chili peppers in arid regions, providing reference for the design of rotary tillage and ridging mulching implements and the development of sustainable agriculture.

Europa's Double Ridges Produced by Ice Wedging

AbstractDouble ridges are sprawling features observed globally across the icy surface of Europa. They consist of two topographic highs flanking a trough. The topographic relief of the ridges is approximately 100 m, and the ridges extend up to hundreds of kilometers in length. The interior structure and dynamics of Europa's ice shell are currently poorly constrained. Therefore, accurate models for the formation of these prominent surface features can be useful for determining how the ice shell operates. We hypothesize that double ridges form as a result of incremental ice wedging. We use both analytical and numerical finite element models to quantify the deformation that occurs as an ice wedge grows incrementally within the ice shell. We show that incremental growth of the ice wedge results in surface deformation that matches the size and shape of typical Europan double ridges, including their topographic relief and surrounding troughs. We find that as the depth of the ice wedge increases, double ridges become broader and shorter. We explore the possibility of local and non‐local sources for the liquid water that freezes to produce the wedge and ultimately argue in favor of local sources of liquid water within the ice shell.

Formation and justification of the parameters of the comb for laying the drip irrigation hose and sowing seeds

The article presents the results of a study on the formation and justification of the parameters of a comb for laying a drip irrigation hose and sowing seeds. The features of the agrometeorological conditions of Uzbekistan during spring sowing are studied. Based on the variability of weather - precipitation, atmospheric air temperature and soil, the parameters of the ridge size are justified. The design of the machine for pre-sowing strip milling of the soil, the formation of the ridge, the laying of the drip irrigation hose, soil compaction, providing physical and mechanical soil of the ridge and the possibility of sowing seeds, is proposed. The design of a milling machine for strip processing with the formation of a ridge of a given shape, composition and parameters, a ridge sealer according to the required soil density has been developed. The main parameters of the comb shaper are substantiated.

Experimental study on fingertip friction perception characteristics on ridged surfaces

Abstract. Fingertip friction perception characteristics have not formed a clear and complete theory, owing to the low repeatability and accuracy of related experiments. Given this, a novel experimental method is proposed based on ridged surfaces for investigating the fingertip friction perception characteristics. In this method, based on the Universal Mechanical Tester (UMT) TriboLab, the proposed experiment makes subjects touch ridged surfaces under different ridge sizes and lubrication conditions, aiming to obtain fingertip friction and subject judgment. Subsequently, the average friction force fluctuation degree and the tactile perception accuracy are calculated to analyze the friction characteristics. For this, the relationship between friction and perception characteristics is discussed further. The results show that the adhesive and the deformation friction forces, which mainly consist of the total friction force under incomplete contact conditions, decrease due to the lubricating oil. However, the adhesive friction force increases slightly as the ridge widens. In addition, when the ridge spacing is raised, the deformation friction force increases and becomes the dominant component, while the adhesive friction force is the opposite. While analyzing the friction characteristics, it is found that the tactile perception accuracy is enhanced by raising the average friction force fluctuation. Moreover, the tactile perception accuracy can be improved by changing the surface texture and lubrication conditions, due to the changes in fingertip friction characteristics.

Performance of a transverse ridge located through the contact zone of an ultra-thin film including surface force effect

PurposeThe purpose of this paper is to investigate the performance of an ultra-thin film lubricated conjunction through the elastohydrodynamic lubrication of point contacts for various ridge shapes and sizes located within the contact zone including flat-top, triangle and cosine wave profiles, considering the influence of surface forces of solvation and Van der Waals’ in addition to the hydrodynamic effect to predict an optimum geometric characteristics for surface texture for lubricated conjunctions.Design/methodology/approachSurface features are simulated in a variety of sizes and shapes including flat-top, triangle and cosine wave profiles. While estimating the elastic deformation of the contacting surfaces, surface forces of solvation and Van der Waals’ are taken into account. The Reynolds equation is solved using the Newton–Raphson method to get the pressure profile and film thickness including the elastic deformation, and surface feature.FindingsThe geometrical characteristics of the ridge, its placement in relation to the contact zone and its height all have a significant impact on the performance of ultra-thin film lubricated conjunction. When the triangular-shaped ridge is present in contact, it forecasts even sharper peaks in film thickness and pressure. More friction, wear and eventually contact fatigue are brought on by this more acute pressure and film thickness peaks. The flat-top ridge shape shows a better performance for lubricated conjunction where, the minimum film thickness value is comparable to that obtained for the case of a smooth contact surface. This behavior is attributed to the effect of intermolecular force of solvation. An increase in the size of the ridge results in a step increase in the film thickness for different ridge shapes, particularly for the flat-topped ridge pattern.Originality/valueEvaluation of the performance of elastohydrodynamic lubricated ultra-thin film conjunction related to film thickness and pressure profile for various ridge surface features of different amplitudes, shapes and sizes located through the contact zone considering the influence of surface forces of solvation and Van der Waals’ in addition to the hydrodynamic effect.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2023-0062/

Effects of ridge parameters on axial spreading of droplet impact on superhydrophobic surfaces

Superhydrophobic surfaces decorated with macrostructures have presented remarkable potential in diverse engineering fields, such as aircraft anti-icing. Understanding the effects of the structure shape and size on droplet dynamics is crucial to the design and application of surfaces. Herein, we investigate the maximum axial spreading for droplets impacting on ridged superhydrophobic surfaces with varied ridge shapes and sizes. We propose a mathematical formula to describe the structure shape with profiles quantified by the shape factor, which is easily applied to structure-related studies. The effects of ridge shape and size on the maximum axial spreading coefficient are clarified. The axial spreading of droplets is inhibited by the ridge due to the outward flow of liquid above the ridge tip. The maximum axial spreading coefficient reduces when the ridge becomes sharper, which can be achieved by increasing the shape factor or the ridge height–width ratio. The complex effect of the ridge–droplet size ratio is divided into two regimes according to the shape factor. Furthermore, a prediction correlation of the maximum axial spreading coefficient is established, which involves the coupled effects of all parameters, agreeing well with experimental and simulation results.

Results of determining the agrotechnical indicators of a flat cutter for fine tillage

In modern conditions, most soils are exposed to erosion processes. In this regard, it is necessary to control the amount of dust particles in the surface layer of the soil. Fine tillage with flat-cutting working bodies solves this issue by creating a finely cloddy soil structure of the upper fertile layer. The article considers the developed original design of a flat cutter for fine tillage. The results of experimental studies on the determination of agrotechnical indicators for the treated background and untreated stubble background are presented. In the course of the research, such indicators were established as: the average actual working depth, the standard deviation of the working depth from the given one, the coefficient of variation in the working depth, crumbling of the soil by the working bodies, the moisture content inside the reservoir, the number of erosion-dangerous particles in the surface soil layer. As a result of the research, it was found that the flat cutter qualitatively performs the specified depth of tillage with an acceptable deviation, the ridge size is in the range of 3.6-3.9 cm, which is allowed by agrotechnical requirements, the number of lumps up to 25 mm in size after the passage of the working body is 82-85% . With shallow tillage with a flat cutter, the removal of wet layers to the soil surface is not observed. The flat cutter can function qualitatively on an untreated stubble background as part of a combined unit that is not equipped with disk working bodies.

FORMATION AND JUSTIFICATION OF THE PARAMETERS OF THE COMB FOR LAYING THE DRIP IRRIGATION HOSE AND SOWING SEEDS

The article presents the results of a study on the formation and justification of the parameters of a comb for laying a drip irrigation hose and sowing seeds. The features of the agrometeorological conditions of Uzbekistan during spring sowing are studied. Based on the variability of weather – precipitation, atmospheric air temperature and soil, the parameters of the ridge size are justified. The design of the machine for pre-sowing strip milling of the soil, the formation of the ridge, the laying of the drip irrigation hose, soil compaction, providing physical and mechanical soil of the ridge and the possibility of sowing seeds, is proposed. The design of a milling machine for strip processing with the formation of a ridge of a given shape, composition and parameters, a ridge sealer according to the required soil density has been developed. The main parameters of the comb shaper are substantiated

Direct force measurement of microscopic droplets pulled along soft surfaces

When a droplet is placed on a soft surface, surface tension deforms the substrate, creating a capillary ridge. We study how the motion of the ridge dissipates energy in microscopic droplets. Using a micropipette based method, we are able to simultaneously image and measure forces on a microscopic droplet moving at a constant speed along a soft film supported on a rigid substrate. Changing the thickness of the thin film tunes the effective stiffness of the substrate. Thus we can control the ridge size without altering the surface chemistry. We find that the dissipation depends strongly on the film thickness, decreasing monotonically as effective stiffness increases. This monotonic trend is beyond the realm of small deformation theory, but can be explained with a simple scaling analysis.

Characterizing the Bounce and Separation Dynamics of Janus Drop on Macrotextured Surface.

Janus drops are thermodynamically stable when a high-viscosity fluid is imposed on a low-viscosity fluid. To understand physical mechanisms in Janus drop impact on macrotextured surfaces, several challenges in finding parameters or strategies still remain. Here, this study investigates the asymmetric bounce and separation of impinging Janus drops on non-wettable surfaces decorated with a macroridge to explore the effect of the drop size, viscosity ratio, and ridge size on the dynamics. Through numerical simulations, we determine the threshold Weber number, above which separation occurs, by varying drop diameters and viscosity ratios of the Janus drops. We investigate the initial bouncing directions of separated drops as a function of the impact velocity and viscosity ratio. We also predict how the separation efficiency is affected by the ridge’s height and width. The asymmetric impact dynamics of Janus drops on macrotextured surfaces can provide new strategies to control drop bouncing in applications, such as liquid separation and purification.

Rotating microstructured spinnerets produce helical ridge membranes to overcome mass transfer limitations

Membrane geometry evolution boosts membrane applications to become even more sustainable, resource- and energy-efficient. This evolution is crucial as increasingly permeable membrane materials introduce the major drawback of promoting fluid resistance due to boundary layer formation. We present how to break these boundary layers with Helical Ridge Membranes produced by rotating microstructured spinnerets. 3D printing enables us to manufacture polymeric, microstructured spinnerets featuring grooved orifices. When integrating these spinnerets into a wet spinning process, microstructured hollow fiber membrane surfaces evolve. Our home-engineered spinning technology sets the spinneret in motion. Rotation twists the nascent microstructure and creates a helical ridge on the lumen side. A robust spinning process especially establishes for our novel spinneret device to rotate the needle inside the spinneret. The interplay of spinning conditions and spinneret rotation uncovers a range of producible helical ridge shapes, sizes and pitches. In addition, spinneret rotation speed affects intrinsic membrane properties, about which we derive general correlations. The helical ridges prove the manipulation of hydrodynamics inside hollow fiber membranes by inducing secondary flow. The latter enhances mass transfer to diminish boundary layers. Ultimately, a cross-flow ultrafiltration showcase reveals TMP gradients reduced by 350% and demonstrates the disruptive impact of Helical Ridge Membranes on membrane filtration.

Ellipsoidal drop impact on a single-ridge superhydrophobic surface

A water drop impacting on a superhydrophobic surface exhibits a complete bounce after a certain residence time bounded by a theoretical time scale. Recent studies have demonstrated that the residence time is modified below the time scale through an asymmetric bouncing on a ridge surface. However, previous studies still assumed initially spherical shapes of drops, focusing on a high impact velocity for a desirable residence time. Herein, we propose asymmetric bouncing dynamics of ellipsoidal drops on a single-ridge superhydrophobic surface to create synergistic cooperation between the initial drop shapes and the ridge structures. Numerical simulations demonstrate the feasibility of reducing the residence time by approximately 55% using a volume-of-fluid method, compared with a conventional drop impact on flat surfaces. We examine how the drop's ellipticity and impact velocity affect the spreading, retraction, and splitting and interpret the underlying mechanism behind the residence time reduction by quantifying the evolutions of the shape and axial momenta of the drops. We also predict the bouncing directions of the drops and the effect of the off-centred distances and ridge sizes in the height and width on the residence time. These findings are expected to illuminate the fundamentals of asymmetric bouncing on a ridge and provide beneficial guidance to strategies such as self-cleaning and anti-icing.

A simple method to align cells on 3D hydrogels using 3D printed molds

Vascular smooth muscle cells align circumferentially around the vessel lumen, which allows these cells to control vascular tone by contracting and relaxing. It is essential that this circumferential alignment is recapitulated in tissue engineered blood vessels. While many methods have been reported to align cells on 2D polymeric substrates, few techniques enable cell alignment on a 3D physiologically relevant hydrogel substrate. We hypothesized that the ridges inherent to the sides of fused deposition modeling 3D printed molds could be used to topographically pattern both stiff and soft substrates and thereby align cells on flat and curved surfaces. Flat and curved molds with 150, 250, and 350 µm ridges were 3D printed and used to topographically pattern polydimethylsiloxane and gelatin-methacryloyl. The ridges transferred to both substrates with less than 10% change in ridge size. Vascular smooth muscle cells were then seeded on each substrate, and nuclear and actin alignment were quantified. Cells were highly aligned with the molded ridges to a similar extent on both the stiffer polydimethylsiloxane and the softer gelatin-methacryloyl substrates. These data confirm that fused deposition modeling 3D printed molds are a rapid, cost-effective way to topographically pattern stiff and soft substrates in varied 3D shapes. This method will enable investigators to align cells on 3D polymeric and hydrogel structures for tissue engineering and other applications.

Modeling and simulation of capillary ridges on the free surface dynamics of third-grade fluid

Abstract Most of the viscoelastic fluids have deformation while flowing over a heated plate. A typical feature of a thin viscous or viscoelastic fluid is the formation of the capillary ridges over locally heated plates. The creation of such ridges in the thin-film surface can affect the smoothness of the coating. This work particularly concerned the flow of non-Newtonian third-grade fluid over an inclined heated plate and the formation of ridges. The conservation laws associated with free surface and wall boundary conditions model the two-dimensional fluid flow. The long wave approximation of the model results in an equation of evolution to explain the structure of free surfaces. The resulting equation is discretized implicitly using the finite volume method. The obtained results are discussed for different flow parameters that affect capillary ridge emergence on the free surface. Variation in the height of capillary ridges of third-grade fluid is compared with the second-grade fluid and Newtonian fluid flow. We observe, the ridge size gets smaller for the third-grade fluid compared to the Newtonian and the second-grade fluid. Our analysis investigates how the third-grade viscoelastic parameters affect the dynamics of the free surface and the size of the capillary ridge concerning temperature changes and other phenomena of interest.

Effect of changing geometrical characteristics for different shapes of a single ridge passing through elastohydrodynamic of point contacts

Purpose The purpose of this paper is to study the behavior of a single ridge passing through elastohydrodynamic lubrication of point contacts problem for different ridge shapes and sizes, including flat-top, triangular and cosine wave pattern to get an optimal ridge profile. Design/methodology/approach The time-dependent Reynolds’ equation is solved using Newton–Raphson technique. Several shapes of surface feature are simulated and the film thickness and pressure distribution are obtained at every time step by simultaneous solution of the Reynolds’ equation and film thickness equation, including elastic deformation. Film thickness and pressure distribution are chosen to be the criteria in the comparisons. Findings The geometrical characteristics of the ridge play an important role in the formation of lubricant film thickness profile and the pressure distribution through the contact zone. To minimize wear, friction and fatigue life, an optimal ridge profile should have smooth shape with small ridge size. Obtained results are compared with other published numerical results and show a good agreement. Originality/value The study evaluates the performance of different surface features of a single ridge with different shapes and sizes passing through elastohydrodynamic of point contact problem in relation to film thickness and pressure profile.

Impact of residual ridge anatomy on masticatory efficiency of conventional complete denture users

ABSTRACT Objective: The aim of this cross-sectional study was to evaluate the anatomical characteristics of edentulous residual ridges in stone casts of complete dentures users and assess correlations with masticatory efficiency. Methods: The sample included 74 study casts, of which 37 were higher and 37 bottom. Measurements were performed using a drypoint compass and a transparent ruler. Arches and ridges of maxillae and mandibles were classified into small, medium, and large. Masticatory efficiency was obtained by the sieve method with the old prostheses and 3 months after placement of new prostheses. The correlations between the anatomical variables of the ridges and arches (height, width and size) and masticatory efficiency were verified by the Spearman correlation test. Significant differences in masticatory efficiencies were assessed by the Wilcoxon test. Results: People with larger maxillary alveolar ridge presented better masticatory performance with old and new dentures. There was no correlation between maxillary ridge width and size with masticatory efficiency, but a correlation was found between maxillary arch width and masticatory efficiency evaluated with the old dentures. Conclusions: With the new dentures, the correlation had a tendency for significance. For the mandible, no correlation was found between height, width, and size of the ridge or with width, length, and size of the arch and masticatory efficiency. In addition, there was no significant difference between masticatory efficiencies evaluated with the old and new prostheses. For the maxilla, ridge height and arch width influence masticatory efficiency. For the mandible, the anatomy had little influence on masticatory performance.

Trabecular bone in domestic dogs and wolves: Implications for understanding human self-domestication.

The process of domestication is complex and results in significant morphological, cognitive, and physiological changes. In canids, some of the traits indicative of domestication of domestic dogs compared to their wild counterparts the wolves are prosociality toward humans, reduced stress hormone levels, and reduced cranial capacity. Research suggests that selection for prosociality among dogs resulted in morphological changes such as reduction in cranial capacity, juvenilization of the face, and overall gracile morphology. Interestingly, similar features have been described in modern humans compared to extinct species of Homo, for example, Neanderthals. Therefore, the human self-domestication hypothesis has been proposed to partially explain the gracile modern human skeleton. Specifically, that as modern humans settled in communities, there was increased selection for prosociality (intergroup cooperation); and one of the by-products of this selection was the evolution of a gracile skeleton, including a slight reduction in cranial capacity, reduced brow ridge and tooth size, and low trabecular bone fraction (TBF). However, TBF variation has not been tested between domestic dogs and wolves, who underwent self-domestication. Thus, this study tests the hypothesis that dogs have low TBF as a consequence of domestication compared to their wild counterparts, the wolves, by comparing TBF in the hindlimbs-proximal femur and distal tibia- of the two species. Wilcoxon rank sum tests show that dogs have lower TBF values than wolves in both elements. These preliminary results add to the literature documenting changes in self-domesticated species and provide a potential analog to further the understanding of self-domestication.

Insertion sites in manual proximal phalanges of African apes and modern humans.

The primary aim of this study was to describe the insertion sites of the ligaments holding the flexor digitorum profundus and superficialis muscles (flexor ridges) in proximal phalanges 2-5 of African apes and modern humans. To interpret differences in flexor ridge size based on general behavioral differences among taxa. We analyzed 3D models of manual proximal phalanges 2-5 from 29 gorillas (Gorilla beringei and Gorilla gorilla), 30 chimpanzees (Pan troglodytes) and 36 recent modern humans. Flexor ridges (mm2) were compared within and across genera. Gorillas and chimpanzees had larger flexor ridges for phalanges 2-4 than humans and this difference subsists when controlling for body size. Each genus had a unique insertion size pattern across the digits, with the most heterogeneous pattern found in chimpanzees, followed by humans, and lastly gorillas. These patterns corresponded strongly to the differences in the size of the phalanges within each genus, except for phalanx 5 in humans, which had a larger flexor ridge than expected. When comparing these genera, the flexor ridges signal differences between taxa that use their hands for manipulation and locomotion (gorillas and chimpanzees) and taxa that use them exclusively for manipulation (humans). This functional signal was also apparent in the PP5 of humans, whose larger FR may be indicating the high recruitment of this digit during forceful precision grip characteristic of humans.