Planar Surface Research Articles

Windage loss characterisation for flywheel energy storage system: Model and experimental validation

In this paper, a windage loss characterisation strategy for Flywheel Energy Storage Systems (FESS) is presented. An effective windage loss modelling in FESS is essential for feasible and competitive design. Unlike generic aerodynamic loss models, FESS require particular attention to their unique characteristics i.e., vacuum, small airgaps, high angular speed, and presence of low friction rotor supports.The proposed model is based on several analytical and semi-empirical windage loss solutions for cylindrical and planar surface interactions, harmonised to manage the transition between laminar and turbulent flows. Also, the model is enriched by introducing corrections for rarefied gasses, using kinetic gas theory formulation. Therefore, it is possible the reduce the windage overestimation occurring with Navier–Stokes equation solutions for laminar flow. The model is compared to case studies from the literature featuring different boundary and operating conditions, to check consistency of all the harmonised models. A dedicated experimental test-rig is developed to validate the corrections to the model for rarefied gas at different vacuum levels. Then, a non-invasive characterisation approach for FESS windage losses in self-discharge phase is proposed and validated on the test-rig.

Effect of curvature on bubble dynamics and associated heat transfer characteristics for nucleate pool boiling from a hydrophilic curved surface

PurposeThis paper aims to carry out numerical study on growth of a single bubble from a curved hydrophilic surface, in nucleate pool boiling (NPB). The boiling performance associated with NPB on a curved surface has been analyzed in contrast to a plane surface.Design/methodology/approachCommercial software ANSYS Fluent 2021 R1 has been used with its built-in feature of interface tracking based on volume of fluid method. For water as the working fluid, the effect of microlayer evaporation underneath the bubble base has been included with the help of user-defined function. The phase change behavior at the interface of vapor bubble has been modeled by using “saturated-interface-volume” phase change model.FindingsAn interesting outcome of the present study is that the bubble departure gets delayed with increase in curvature of the heating surface. Wall heat flux is found to be higher for a curved surface as compared to a plane surface. Effect of wettability on the time for bubble growth is relatively more for the curved surface as compared to that for a plane surface.Originality/valueEffect of surface curvature has been investigated on bubble dynamics and also on temporal variation of heat flux. In addition, the impact of surface wettability along with the surface curvature has also been analyzed on bubble morphology and spatial variation of heat flux. Furthermore, the influence of wall superheat on the bubble growth and also the wall heat flux has been studied for fixed angle of contact and varying curvature.

Investigating the Role of Flow Plate Surface Roughness in Polymer Electrolyte Membrane Fuel Cells with the Use of Multiphysics Simulations

This study investigates the influence of surface roughness on the performance of polymer electrolyte membrane fuel cells (PEMFCs) through computational simulations using COMSOL Multiphysics. Two distinct gas flow channel (GFC) models of serpentine and parallel GFC structures were analysed, featuring various surface roughness levels to examine their impact on gas pressure and velocity dynamics. Rough surfaces are modeled using trigonometric functions to replicate machining-induced variations. Finite element simulations were conducted, assessing the time-dependent relationship between gas pressure and velocity while considering different electrode phase potentials as a function of surface roughness. Rough surfaces generally enhance mass transport, water management, and current distribution compared to smooth surfaces. The results indicated that a surface roughness of approximately 1 µm optimizes PEMFC performance by balancing pressure and velocity, enhancing electrochemical reactions, and reducing excessive pressure drops within the cell. Notably, the 0.7 V operating voltage was found to be the most efficient, achieving rapid stabilization of pressure and velocity levels swiftly. The findings underscore the importance of precise control over GFC roughness to enhance PEMFC performance gains in commercial applications, especially when multiple cells are stacked to achieve high power outputs.

Contact angle calculations for argon and water sessile droplets on planar lyophilic and lyophobic surfaces within molecular dynamics modeling

There exist many ways to calculate the contact angle of a sessile droplet on a planar surface on the basis of molecular modeling data, and the result may depend on the chosen approach. This paper presents molecular dynamics simulations of argon and water sessile droplets on simple model and more complex atomistic substrates. Several approaches for calculating contact angles are described. These approaches are based on an analysis of instantaneous droplet’s configurations and averaged density profiles. The latter are analyzed using density cutoffs and the Sobel filters. Parameters of the interaction between the planar surface and the fluid are being tuned in order to consider model lyophilic and lyophobic substrates. Dependences of the contact angle on the strength of interaction between the fluid and the substrate and on the droplet size are obtained. The apparent line tensions for the observed sessile droplets are evaluated.

Proper orthogonal decomposition analysis of flow characteristics of aerostatic bearings based on Large Eddy Simulation

The driving mechanism of the vibration of aerostatic bearings is still unclear. Although there are several interpretations, none of them is conclusive. The difficulty lies in the complicated information concealed beneath the turbulence flow. To this end, the proper orthogonal decomposition (POD) method was systematically implemented in the aerostatic bearing flow field analysis in the present study, and some new findings have been proposed. First, the accuracy of our large eddy simulation (LES) has been validated through quantitative comparisons with the experimental references in terms of pressure distribution. Then, the mode decomposition has been conducted at a circumferential symmetry plane and bottom surface and the influence of supply pressure has been uncovered. It turns out that the vortices within the recess dominate the flowfield when the supply energy Ps=3atm, which could be recognized as the driving mechanisms of vibrations. The convection and shearing process in the vicinity of the recess inlet becomes intense and corresponding vortices become predominant in the cases of Ps=4atm and 5atm. Eventually, the influences of film thickness have also been discussed when Ps=4atm. Different from the case of h = 10 μm, the low-frequency vortices near the recess outlet could be detected when the film thickness is increased to 20 µm. The control of corresponding flow structures might be helpful for the vibration suppression.

Tailoring particle size/morphology for the stable cathode performance of polygonal-shaped Li(Ni,Mn)2O4 single crystals

We regulate the particle size and crystallographic facet of single-crystal (SC) Li(Ni,Mn)2O4 (LNMO) cathode materials via flux-selective molten salt method. By simply adjusting Li2MoO4 or LiI as sintering aids, we synthesized size controlled SC particles, both small and large, and comparatively investigated their electrochemical behavior focusing on the lithiation/delithiation reactivity in conjunction with the particle size and surface planes. Considering the growth mechanism of a SC particles with a specific crystal plane, such particle size control is not determined solely by the synthetic condition but must also consider the interfacial energy of the crystal planes in conjunction with the fluxes what we used. While the initial charge capacity is similar, the given cathode using a small SC LNMO (using LiI) with uniform particle sizes (≤5 μm) exhibits outstanding rate capability with stable capacity retention under changing current density, which indicates stable lithium transport during the repetitive electrochemical reactions. The dependency of the impedance response with change in the electrode resistances as well as the stability during the cycle reactions in conjunction with the post-mortem Li distribution by using laser-induced breakdown spectroscopy as a function of porosity change and cell degradation are thoroughly discussed from the standpoint of regulated particle property.

Unsupervised method for detecting surface defects in steel based on joint optimization of pseudo-labeling and clustering

Abstract Advances in the field of measurement science and technology have improved the detection of defects in industrial production. One of the key challenges in steel plate surface defect detection is the need to quickly detect a small number of defects in an overwhelmingly defect-free sample. Unlike supervised learning, which relies heavily on precise sample labeling, unsupervised learning leverages its inherent learning capabilities for detection. This paper introduces an innovative method for smart steel diagnosis, integrating joint optimization of feature extraction and clustering. The proposed approach merges mini-batch K-Means clustering with a feature extraction network to acquire pseudo-label information for current images. It employs a multi-view transformation strategy, enabling classification through the optimized feedback from pseudo-labels. This method allows the network to self-optimize the distinction of image features through backpropagation. The method exhibits a mere 4% classification failure rate for steel surface images. This significant reduction in additional data processing requirements enhances the inspection system's efficiency and accuracy. Furthermore, the versatility of this method extends beyond steel defect diagnosis. It holds potential for application in various engineering domains, particularly in scenarios characterized by data imbalance.

Structure of Silicon Wafers Planar Surface before and after Rapid Thermal Treatment

Presently it is important to remove mechanically disturbed layer on wafer surface during creation of up-to-date microelectronic products. Rapid thermal treatment with optical pulses of second duration is one of the applicable methods for removing disturbances in crystal lattice emerging after ion implantation. However the crystal structure of mechanically disturbed layer on wafer planar side is still unclear. Researches by transmission electronic method, analysis of diffraction reflection curve and electronic Auger spectroscopy has failed to provide reliable data about the state of crystal lattice in surface layer of at least 30 nm thickness. Hence it was impossible to suggest a model of solid phase recrystallization and to present its mathematical description. The goals of the work were as follows: – identify of silicon crystal lattice state in surface layer of 30 nm thickness before and after rapid thermal treatment by backward reflected electrons diffraction method using raw Si wafers surface; – analysis of contamination element composition on the surface of raw silicon before and after rapid thermal treatment; – model development for solid phase recrystallization of surface disturbed layer after rapid thermal treatment and its mathematical description. Images of back ward reflected electrons diffraction using surface layer of raw silicon wafers' of 30 nm thickness and also the results of the planar surface of raw silicon wafers' cleaning from impurities are provided. Processes reducing the activating energy of mechanically disturbed silicon layer recrystallization process were suggested and its mathematical description was provided. Parameters of rapid thermal treatment mitigating the thermal impact on silicon wafer for recrystallization of mechanically disturbed layer on its planar surface ware defined.

Optimum Solar Cell Power Conversion Efficiency-Based Patterned Planar Solar Surface Morphology with Various Solar Cell Absorber Structures

This paper simulated the optimum solar cell power conversion efficiency-based planar solar surface morphology with various solar cell absorber structures. The spectral light intensity, reflected, absorbed, and transmission coefficients versus wavelength band spectrum varied from 300[Formula: see text]nm to 1300[Formula: see text]nm through the visible to near-infrared regions. The optimum solar cell performance parameters or key parameters are studied with different solar cell structure designs based on different surface contact and back contact layers. Cumulative generation current, cumulative electron–hole pair generation rate and electron–hole pair generation rate are clarified versus substrate depth for various solar cell structure designs. The absorbed current in substrate is optimized for various solar cell structure designs. Maximum power voltage and current are also optimized for the proposed solar cell structure design. The effective solar cell power efficiency is also demonstrated based on the optimized maximum power current and maximum power voltage.

Cold Storage and Release Characteristics of Phase Change Cold Storage Plate with Non-Uniform Fins

Ice plates, widely used in food cold chain refrigeration transportation, involve challenges such as long cold storage time and low efficiency in use. This study establishes a mathematical model for ice plate cold storage and release. It analyzes the influence of fin setting position, distribution, and size on the cold storage and release characteristics of non-uniform fins having diverse sizes and spacing on the inner and outer surfaces of the ice plate. Results show that compared to finless ice plates, plates with inner or outer fins can reduce the cold storage and release time, accelerate the charging and discharging efficiency of the cold storage equipment, and potentially save time. Cold storage and release time savings of up to 17.5% and 19.6%, respectively, were attained using outer fins. Driven by natural convection inside the finned ice plate, cold storage proceeds from top to bottom, while cold release proceeds from bottom to top. For inner fins, the distribution has a higher impact on the cold storage and release speed than the size. For outer fins, both the distribution and size equally affect the cold storage and release speed. The smaller the reference spacing between the outer fins, the faster the cooling storage, but the slower the cold release. The larger the reference area, the faster the cooling storage, but the slower the cold release. Thus, when designing ice plate products, the distribution and the size of fins should be selected based on prior consideration of storage or release speed. This study provides a theoretical basis and design guidance for the design of ice plate products, especially for refrigerated transportation applications.

A vision measurement method for ship hull plates based on multi-view stereo and image segmentation

The background denoising of point clouds is challenging for the measurement of ship hull plates. To address this issue, a vision measurement method is proposed by combining an identity cost volume network (ICV-Net) and a segment anything model (SAM). By applying the ship hull plate masks segmented by SAM to the corresponding depth maps inferred by ICV-Net, the background noise can be directly removed at the depth map level. Additionally, an edge extraction optimization algorithm complementary to SAM is proposed to eliminate the thickness-related noise. Moreover, an efficient depth map refinement algorithm is proposed by imposing the smoothness prior of ship hull plate surfaces and multi-view photometric consistency. Sub-pixel accurate depth maps of ship hull plates can be obtained by the depth map refinement. Experimental results suggest that the proposed method can automatically, accurately and efficiently remove the background noise of ship hull plates, which is crucial toward practical application.

Pictorial depth cues elicit the perception of tridimensionality in dogs

The perception of tridimensionality is elicited by binocular disparity, motion parallax, and monocular or pictorial cues. The perception of tridimensionality arising from pictorial cues has been investigated in several non-human animal species. Although dogs can use and discriminate bidimensional images, to date there is no evidence of dogs’ ability to perceive tridimensionality in pictures and/or through pictorial cues. The aim of the present study was to assess the perception of tridimensionality in dogs elicited by two pictorial cues: linear perspective and shading. Thirty-two dogs were presented with a tridimensional stimulus (i.e., a ball) rolling onto a planar surface until eventually falling into a hole (control condition) or until reaching and rolling over an illusory hole (test condition). The illusory hole corresponded to the bidimensional pictorial representation of the real hole, in which the pictorial cues of shading and linear perspective created the impression of tridimensionality. In a violation of expectation paradigm, dogs showed a longer looking time at the scene in which the unexpected situation of a ball rolling over an illusory hole occurred. The surprise reaction observed in the test condition suggests that the pictorial cues of shading and linear perspective in the bidimensional image of the hole were able to elicit the perception of tridimensionality in dogs.

Identification of cracks and mathematical model of the magnetostatic field of defects in a plate

A mathematical model of defects in the inner surface of a ferromagnetic plate is presented. The model compares crack-type defects with wide-opening corrosion defects.

Study of Heat Flow at Substrate during Sputtering of Copper-Titanium Sandwich Target.

The purpose of this work is to study the kinetics of the heat flow heating the substrate, which is generated by a two-layer sandwich magnetron target when sputtered in argon. Its novelty resides in the application of the COMSOL Multiphysics to study the kinetics of thermal processes during sputtering of a target of the new type. The analysis was performed for a sandwich target with internal copper and external titanium plates when the discharge power varied in the range of 400-1200 W. The heating of the external target plate is described by a two-dimensional homogeneous Fourier equation. The solution to the equation reveals how the kinetics of the external plate's surface temperature distribution depends on the discharge power. To study the heat flow heating the substrate, the external plate is presented in the form of an additive set of small-sized surface heat sources. Previously unknown features of the thermal process are established. It is shown that numerical modeling adequately describes the experimental results.

Endoprosthetic replacement with preservation of the epiphysis for proximal tibial reconstruction after osteosarcoma resection in children: a case report

BackgroundLimb salvage surgery is an important method for treating malignant tumors of the bone involving the adjacent parts of the major joints in children. This technique allows for preservation of limb function, especially in the lower limb. However, the reconstruction of the proximal end of the tibia after removing the tumor mass with a rational scale to preserve the total knee joint and reduce limb length discrepancy presents a challenge.Case presentationWe present a case of osteosarcoma of the proximal tibia. After being treated with an extended tumor resection, the proximal tibia of the child was restructured using endoprosthetic replacement with epiphyseal preservation. This procedure preserves the entire articular surface and growth plate of the knee joint of the affected limb and provides a feasible alternative protocol for retaining the function and growth potential of the affected limb. The patient remained disease-free and normal limb motor function was observed during the 3.5 year follow-up since the initial surgery.ConclusionsPreservation of the epiphysis enabled our patient to perform better limb function after limb-saving surgery as a result of his undamaged knee joint and minimized limb-length discrepancy. We believe that endoprosthetic replacement with preservation of the epiphysis can provide the best strategy for reconstruction after resection of focal malignant tumors in long bones without epiphytic involvement.

Warpage control and interface characteristics of Ti/Al composite plates by differential temperatures rolling with mobile induction heating

This study addresses the issue of warping and low interfacial bonding strength in composite plates due to uncoordinated deformation during the rolling of titanium/aluminum composites. By adopting mobile induction heating with differential temperature rolling composite technology, heated titanium plates and room-temperature aluminum plates were successfully rolled into composites. The results show that when the titanium plate is heated to 500–900°C, the warpage of the titanium/aluminum composite plates first decreases and then increases, while the interface shear strength first increases and then decreases. It is particularly emphasized that the rolled composite plates is straight at 800°C, the Ti6O oxide layer formed on the titanium plate surface exhibits excellent adhesion to the substrate, while displaying susceptibility to cracks during the rolling process, allowing fresh aluminum metal to be squeezed into the cracks to form a mechanical mesh and an atomic bonding diffusion layer occurs due to the fresh metal contact between titanium and aluminum within the crack, thereby resulting in the composite plates exhibiting optimal shear strength. The findings verify the preliminary feasibility of the proposed novel rolling process and provide a novel solution for prepared titanium/aluminum composite plates, which is an important step for future fabrication and applications of composite plates.

Astragalus Extract Mixture HT042 Alleviates Dexamethasone-Induced Bone Growth Retardation in Rat Metatarsal Bones.

The most widely used synthetic glucocorticoid, dexamethasone (DEX), causes stunted growth in children when used excessively or for long periods of time; however, there are still plenty of pediatric patients require long-term treatment with DEX. As an alternative, growth hormone is used in combination, but it has side effects, a high cost, and psychological factors, and it is not satisfactory in terms of effectiveness. It is necessary to develop a safe and affordable treatment that can replace it. The Korean Food and Drug Administration approved HT042, a standardized functional food ingredient, with the claim that it can help height growth of children. In this study, it was found that HT042 activated the Indian hedgehog/parathyroid hormone-related protein signaling pathway and enhanced the number of growth hormone receptors and insulin-like growth factor-1 receptors on the growth plate surface, which were reduced by DEX treatment, and restored growth retardation. In metatarsal bone and primary chondrocyte models, it was found that HT042 can promote the length of growth plate and recover DEX-induced growth retardation. It was also found that HT042 promotes cell proliferation using bromodeoxyuridine and terminal deoxynucleotidyl transferase dUTP nick end labeling assays; moreover, we verified increased expression of GHR/IGF-1R and Ihh/PTHrP pathway activity using qRT-PCR, western blotting, and siRNA analyses to verify its direct action on the growth plate. The anti-apoptotic effect of HT042 was identified by regulating the expression of apoptotic factors such as caspase-3, Bcl2, Bclx, and Bax. These results were identified using both ex vivo and in vitro models. Our study verified that co-administration of HT042 could recover the DEX induced growth retardation.

Asymmetric vehicle performance assessment using GG diagrams

In closed-circuit racing such as NASCAR, vehicles often travel on highly-banked oval tracks that are dominated by left-hand corners. The aim of this paper is to study the generation and interpretation of the associated asymmetric GG diagrams and performance metrics. These include GG diagrams on inclined and/or cambered planar road surfaces, and GG diagrams on curved surfaces such as the interior face of an inverted cone. It is shown that a general fixed point on a traditional GG diagram is associated with acceleration or braking along a logarithmic spiral. Under pure acceleration and braking this spiral becomes a straight line, while under constant-speed cornering it becomes a circle. Some of these ideas are developed using a single-track car model. The paper then addresses the calculation and interpretation of GG-diagrams and performance metrics for a Generation 7 (Gen-7) NASCAR on curved road surfaces. The car's stability and performance limits under extreme lateral acceleration conditions are of particular interest. The main results come from a high-fidelity vehicle model and a representative set of parameters.

Preparation of oil-in-water type Pickering emulsions stabilized by partially deacetylated nanochitin and pH-triggered drug release

Partially deacetylated nanochitin (DAcNC) exhibits amphiphilicity owing to the hydrophilic protonated amino groups and hydrophobic surface planes of DAcNC. Although DAcNCs possess emulsifying abilities, their role and versatility as emulsifiers remain unclear. In this study, we investigated oil-in-water (O/W) type Pickering emulsions stabilized with DAcNCs. Stable emulsions were formed using a variety of oils such as vegetable oils, decane, and ether oils. Measurements of the interfacial tension and adsorption of DAcNC showed that formation of tolerant interfacial films stabilized the emulsions. Furthermore, the pH-triggered release of ibuprofen, an antipyretic drug, was demonstrated using the emulsion. Enhanced ibuprofen release was observed upon increasing the pH from 2.0 to 6.0. This phenomenon can be attributed to the deprotonation of ammonium moieties on the DAcNC, which induced the desorption of DAcNC from oil/water interfaces. The DAcNC emulsion can be useful for the oral administration of ibuprofen as an antipyretic agent, facilitating intestinal release.

Enhancing the Kinetics of Vapor-based Polymerization by Pulsed Filament Approach.

Initiated chemical vapor deposition is a versatile technique for synthesizing conformal polymer films on both planar and porous surfaces. It can retain functional groups and avoid undesired cross-linking. However, there is still room for enhancing its performance without altering the feed parameters. Here, we investigate a pulsed iCVD approach to improve the deposition process, achieved by switching on and off the resistively heated filament periodically. By strategically switching off the filament, a shortage of thermally activated primary radicals was created, which allowed uninterrupted chain propagation with fewer termination reactions and potentially increased monomer conversion rates. This has caused significantly faster deposition kinetics with a higher molecular weight and longer chain length for poly(glycidyl methacrylate) compared to continuous deposition. Spectra analyses confirmed that the functionality and stoichiometry ratios remained intact throughout the pulsed deposition process. The pulsed iCVD method is therefore a competitive and sustainable tool, demonstrating fast deposition kinetics and a well-preserved functionality.