Layer Mesh Research Articles

Experimental assessment of a multilayered packed-sphere La–Fe–Si active magnetic regenerator

This study investigates the performance of a multilayered packed-bed active magnetic regenerator (AMR) using spheroidal particles with first-order magnetocaloric properties. The hydraulic performance is assessed via the interstitial friction factor, showing significant underestimation by the Ergun Equation at high mass flow rates. Coefficient adjustments are made to accurately represent the AMR pressure drop, considering particle nonuniformity and structural components, such as layer mesh dividers. This facilitates the pressure drop modeling and provides a means to check the AMR integrity on a routine basis, without requiring AMR disassembly. The thermal performance, evaluated in terms of the regenerator effectiveness, shows a satisfactory cooling potential for practical applications but emphasizes the need for flow control to prevent effectiveness imbalance between hot and cold flows, crucial for optimal operation. The cooling capacity and maximum temperature span are also evaluated, demonstrating that higher mass flow rates yield higher cooling capacities with lower temperature spans, while lower rates achieve higher spans. Varying the blow fraction shows that regenerators at 50% blow fraction achieve 10% higher cooling capacities than at 37.5%. Increasing operational frequency improves cooling by increasing the number of cycles and reducing losses, resulting in a 15% capacity increase between 0.25 and 0.50 Hz. However, this trend may reverse at higher frequencies beyond the experimental limits. While this study improves the understanding of the hydraulic and thermal performance of packed-bed AMRs, its findings underscore the importance of flow balance and frequency in achieving optimal performance, thus providing insights for future system improvements.

Investigation of the aerodynamic characteristics of the entire operation process of the car–counterweight system within the annular flow field of ultra-high-speed elevators

The ultra-high-speed elevator car–counterweight system will experience substantial aerodynamic effects when operating at high speeds in the annular flow field, particularly at the moment of intersection. These effects will have a considerable impact on the stability of the elevator's operation. This study utilized the unsteady Reynolds-averaged Navier–Stokes approach to investigate the aerodynamic characteristics of the car–counterweight system's entire operation process. The ultra-high-speed elevator three-dimensional transient model is created using dynamic layering mesh technology and then validated through experiments. We investigate the impact of three crucial factors—acceleration, car height, and contact ratio—on the aerodynamic characteristics of the car and the ventilation effect in the hoistway. Specifically, we analyze the instantaneous variations in the aerodynamic force of the car during the intersection process. The results indicate a rapid change in the car's drag and lift at the moment of intersection, with a greater magnitude of change observed in the pressure drag. The acceleration increases gradually, while the drag peak at the intersection time decreases by 1.8%, 3.0%, and 3.6%, respectively. Additionally, the hoistway exhaust volume ratio decreases by 0.9%, 1.5%, and 2.0%. Compared to the drag peak, the lift peak is more responsive to variations in car height. The contact ratio exhibits a sequential increase, but the lift peak demonstrates an uneven upward pattern with increments of 3.07%, 10.35%, and 16.88%. This study greatly enhances the investigation of the aerodynamic characteristics of ultra-high-speed elevators and offers a crucial point of reference for optimizing elevator design in engineering.

EFFECTS OF CONTINUOUS AND FRACTURED RIBS PLACED AT THE ENDWALL SURFACE UPSTREAM OF THE TURBINE-VANE LEADING-EDGE

Total pressure loss, chaotic and heavy flow downstream of the turbine passage exit area are a few effects of the desired increase in inlet temperature input at the upstream part of the turbine vane passage. Huge amount of energy from the cross-flows near the middle of the vane actual chord are transported downstream by this chaotic flow which often results in aerodynamic loss and differential heat penalties. To compare the different arrangement, comparisons of the two geometries, the impact of adding various rib configurations upstream are studied for heat augmentation efficacies. The leading-edge rib(s) effects at the mid-stream of the vane passage are quantitatively examined in this work using computational fluid dynamics (CFD) technique. With the employment of Reynolds Averaged Navier-Stoke energy equations, the geometries are modelled choosing the appropriate boundary conditions. Polyhedral mesh is used with fifteen prism layer mesh at the endwall and vane surfaces to capture the flow physics close to the endwall area. Although the two configurations employed showed relative reduction in the total pressure loss coefficient, however, the fractured ribs produced superior outcomes of Nusselt number reduction of over 10% along the passage exit region. The data demonstrate a considerable difference in the overall pressure loss between the two configurations.

Numerical calculation of air permeability of warp-knitted jacquard spacer shoe-upper materials based on CFD

Abstract In order to realize the rapid design of warp-knitted jacquard spacer shoe-upper materials and to explore the influence of different fabric surface organization structures on their air permeability, it is proposed to numerically simulate the air permeability performance of jacquard shoe-upper materials using ANSYS fluid analysis. First, four kinds of shoe material specimens with different upper and lower layer mesh alignment relationships are designed and tested, then the corresponding geometric structure models of the fabric are established based on the samples and appropriately processed, and finally the air permeability of the shoe material is numerically simulated and calculated based on computational fluid dynamics. The results show that, under the same conditions, the air permeability of double-sided mesh structure is significantly better than that of single-sided mesh structure, and its air permeability can be optimized by adjusting the relationship between the upper and lower layers of the fabric mesh; the airflow mainly passes through the fabric pores and gaps between the yarns, and the closer the fabric structure is, the more the air flow is hindered, and the worse the air permeability is. The simulation results of the established numerical model are consistent with the measured results, and the error is less than 10%, so it can be used to simulate and predict the air permeability of the warp-knitted jacquard spacer footwear materials, and provide theoretical support for the design and performance research of footwear materials.

Bottlebrush Polyethylene Glycol Nanocarriers Translocate across Human Airway Epithelium via Molecular Architecture-Enhanced Endocytosis.

Pulmonary drug delivery is critical for the treatment of respiratory diseases. However, the human airway surface presents multiple barriers to efficient drug delivery. Here, we report a bottlebrush poly(ethylene glycol) (PEG-BB) nanocarrier that can translocate across all barriers within the human airway surface. Guided by a molecular theory, we design a PEG-BB molecule consisting of a linear backbone densely grafted by many (∼1000) low molecular weight (∼1000 g/mol) polyethylene glycol (PEG) chains; this results in a highly anisotropic, wormlike nanocarrier featuring a contour length of ∼250 nm, a cross-section of ∼20 nm, and a hydrodynamic diameter of ∼40 nm. Using the classic air-liquid-interface culture system to recapitulate essential biological features of the human airway surface, we show that PEG-BB rapidly penetrates through endogenous airway mucus and periciliary brush layer (mesh size of 20-40 nm) to be internalized by cells across the whole epithelium. By quantifying the cellular uptake of polymeric carriers of various molecular architectures and manipulating cell proliferation and endocytosis pathways, we show that the translocation of PEG-BB across the epithelium is driven by bottlebrush architecture-enhanced endocytosis. Our results demonstrate that large, wormlike bottlebrush PEG polymers, if properly designed, can be used as a carrier for pulmonary and mucosal drug delivery.

Emission characteristics of a forevacuum plasma-cathode source of wide-aperture pulsed electron beam with layer (mesh) stabilization of emission plasma

Research of emission characteristics of a pulsed forevacuum plasma electron source with layer (mesh) stabilization of emission plasma boundary has been carried out. Generation of a pulsed wide-aperture electron beam is provided by DC accelerating voltage (1–10 kV) and pulse-periodic formation of emission plasma by a cathodic arc with current 5–80 A, pulse duration 500–600 μs. Pressure (4–30 Pa) and the type of working gas (N2, O2, Ar, He, Kr) significantly influence on the emission characteristics of the forevacuum plasma electron source. An increase in the gas pressure and the use of gas with larger ionization cross-section provide an increase in the electron emission current. At low pressure (below a certain threshold value, which determined by the type of gas) an increase in the discharge current leads to an increase in the efficiency of electron emission. But at pressures more than the threshold value the emission efficiency decreases as the discharge current increases. The influence of pressure and type of gas on the emission characteristics are caused by the ion flux from the beam plasma which is formed due to ionization of gas by accelerated beam's electrons.

Analysis of flow characteristics of a pump turbine under the transient condition of 75% load rejection

Abstract In this study, the flow calculations for a pump turbine under the transient condition of 75% load rejection was conducted. The model incorporated a boundary layer on the surface of the guide vane, with the node coordinates of each element in the boundary layer region being updated. This approach ensured the stability of the boundary layer mesh. Experimental measurements provided parameter curves for inlet pressure, outlet pressure, runner speed, and guide vane opening over time. The pressure fluctuation at each monitoring point was compared with the experimental data, and a good agreement was found. Additionally, the variation curve of the axial hydraulic thrust of the head cover and the pressure distribution nephogram of the head cover at typical moments were analysed. The results of this study could be used as a reference for the safe and stable operation of pumped-storage power stations.

FaceFolds: Meshed Radiance Manifolds for Efficient Volumetric Rendering of Dynamic Faces

3D rendering of dynamic face captures is a challenging problem, and it demands improvements on several fronts---photorealism, efficiency, compatibility, and configurability. We present a novel representation that enables high-quality volumetric rendering of an actor's dynamic facial performances with minimal compute and memory footprint. It runs natively on commodity graphics soft- and hardware, and allows for a graceful trade-off between quality and efficiency. Our method utilizes recent advances in neural rendering, particularly learning discrete radiance manifolds to sparsely sample the scene to model volumetric effects. We achieve efficient modeling by learning a single set of manifolds for the entire dynamic sequence, while implicitly modeling appearance changes as temporal canonical texture. We export a single layered mesh and view-independent RGBA texture video that is compatible with legacy graphics renderers without additional ML integration. We demonstrate our method by rendering dynamic face captures of real actors in a game engine, at comparable photorealism to state-of-the-art neural rendering techniques at previously unseen frame rates.

Numerical Simulation of Double Layered Wire Mesh Integration on the Cathode for a Proton Exchange Membrane Fuel Cell (PEMFC)

The optimization of reactant and product mass transfer within fuel cells stands as a critical determinant for achieving optimal fuel-cell performance. With a specific focus on stationary applications, this study delves into the comprehensive examination of fuel-cell mass transfer properties, employing a sophisticated blend of computational fluid dynamics (CFD) and the innovative design of a double-layered wire mesh (DLWM) as a flow field and gas diffusion layer. The investigation notably contrasts a meticulously developed 3D fine mesh flow field with a numerical model of the integrated DLWM implemented on the cathode end of a proton exchange membrane fuel cell (PEMFC). Evaluations reveal that the 3D fine mesh experiences a notable threefold increase in pressure drop compared to the DLWM flow field, indicative of the enhanced efficiency achieved by the DLWM configuration. Oxygen distribution analyses further underscore the promising performance of both the 3D fine mesh and the proposed DLWM, with the DLWM showcasing additional improvements in water removal capabilities within the cell. Impressively, the DLWM attains a remarkable maximum current density of 2137.17 mA/cm2 at 0.55 V, indicative of its superior performance over the 3D fine mesh, while also demonstrating the potential for cost-effectiveness and scalability in mass production.

Performance of RC beams developed with ECC layer and AR glass fiber mesh under flexural loading

Performance of RC beams developed with ECC layer and AR glass fiber mesh under flexural loading

Study on Resistance Loss of Fly Ash Slurry Multistage High‐Pressure Grouting Pipeline Based on Fluent

In order to understand the resistance loss along the way during multistage high‐pressure slurry transportation, the flow state of fly ash slurry in the pipeline was simulated by Fluent software in this paper, and the effects of pipe diameter D, pipe transportation flow rate Q, and fly ash mass concentration Cw on the resistance loss along the pipeline were studied. The fly ash slurry is a non‐Newtonian Bingham fluid that moves in a turbulent state in a pipeline. When simulating the flow of fly ash slurry using Fluent software, the mesh type is a mixed mesh of hexahedron and wedge shapes, and the viscous model is selected as realizable k‐ε Turbulence Model, with Enhanced‐Wall Function (EWF) selected as the wall function, combined with a four‐layer boundary layer mesh, which can more accurately capture the details of velocity changes at the wall, thereby improving the accuracy of the model. The inlet of the model is the velocity inlet, and the outlet is the pressure outlet. The coupled algorithm is chosen as the solution method. Under these conditions, the model converges quickly and the calculation accuracy is high. The results show that the resistance loss along the pipeline decreases as a power function with the increase of pipeline diameter, and there is a polynomial relationship between the pipeline flow and the resistance loss along the pipeline, while the mass concentration of fly ash slurry changes linearly with the resistance loss along the pipeline. In addition, three friction coefficient models, namely Blasius formula, Colebrook–White equation, and Wilson–Thomas model, were selected according to the flow characteristics of fly ash slurry. Based on the Blasius formula with the smallest relative calculation error, the Blasius formula was modified by multiple linear regression analysis to improve the accuracy of the frictional resistance coefficient model and to provide help for the design and use of separate layer grouting conveying system.

Harnessing CFD Modeling Techniques for Optimizing Automotive Streamlines and Reducing Aerodynamic Drag

Computational fluid dynamics (CFD) has emerged as an indispensable tool in automotive design, significantly enhancing vehicle performance through aerodynamic optimization. This paper offers a comprehensive exploration of the application of CFD modeling techniques in refining automotive streamline designs, with the overarching goal of mitigating aerodynamic drag and amplifying vehicle efficiency. To contextualize the discussion, the author commences with a historical overview of fluid dynamics, segueing into a detailed exposition of core CFD algorithms, numerical methodologies, and advanced modeling approaches encompassing boundary layer dynamics, turbulence modeling, meshing strategies, and coupling techniques. Through illustrative case studies, the author elucidates the transformative impact of CFD in streamlining the design process and achieving tangible drag reduction outcomes. The discourse extends to the implications of CFD on fuel economy, vehicular speed, stability, and holistic design considerations. In conclusion, the author addresses the challenges inherent in transposing CFD insights to tangible automotive applications and charts prospective trajectories for CFD's continued evolution in automotive engineering, underscoring its pivotal role in steering the future of vehicular design.

Measurements and Prediction of Ash Deposition in a Cyclone-Fired Boiler Operating under Variable Load Conditions

Measurements of ash deposition rates were made between the secondary superheater and reheater sections of a 450 MW cyclone-fired lignite boiler as the operational load varied from 33 to 100%. Significant reductions in deposition rates with a decrease in operational load were observed. To uncover the causative mechanisms behind these observations, operational data from the power plant were used to carry out computational fluid dynamic (CFD) simulations of the boiler. After ascertaining that the gas temperatures and velocities at various sections within the boiler were being represented adequately, decoupled simulations of the ash deposition process on the deposit probe were carried out using a finely resolved boundary layer mesh. Fly ash particle size distribution (PSD) and its concentration for the decoupled calculations were determined from stand-alone cyclone barrel simulations. The ash partitioning (mass %) between the fly ash and slag was found to be ~50:50, which was in line with previous field observations, and it did not vary significantly across different cyclone loads. The predicted PSD of the deposit ash was concentrated in the size range 10–30 microns, which was in agreement with cross-sectional images of the deposit obtained from the measurements. At lower loads, sharp variations in the deposition rates were predicted in the gas temperature range 950–1150 K. The particle kinetic energy—particle viscosity-based capture methodology utilized in this study in conjunction with appropriate ash compositions, ash viscosity models and gas temperature estimates can help estimate slagging propensities at different loads reasonably well in these systems.

Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

Slug flow or high GVF (Gas Volume Fraction) conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps, endangering the safety of multiphase pump units. The mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation model. UDF (User Define Function) programs such as structural dynamics equations, alternating load equations, and pressure disturbance equations are embedded in numerical calculations, and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh technology. The results show that when the pressure disturbance occurs at the inlet, as the amplitude and period of the disturbance increase, the film thickness gradually decreases. And the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely manner. The maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance amplitude. The mutual interference between enhanced waves does not have a significant impact on the film thickness, while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes, and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial values. Compared with pressure disturbance conditions, alternating load conditions have a more significant impact on film thickness and leakage. During actual operation, it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

An hp Weak Galerkin FEM for singularly perturbed problems

We present the analysis for an hp Weak Galerkin-FEM for singularly perturbed reaction-convection-diffusion problems in one-dimension. Under the analyticity of the data assumption, we establish robust exponential convergence, when the error is measured in the energy norm, as the degree p of the approximating polynomials is increased. The Spectral Boundary Layer mesh is used, which is the minimal (layer adapted) mesh for such problems. Numerical examples illustrating the theory are also presented.

12-Month Outcomes of Carotid Artery Stenting With CGuard MicroNET-Covered Stent: A Single-Center Study in 113 Patients.

Dual layer mesh stents constitute a novel treatment option for patients who undergo carotid artery stenting (CAS). The aim of this prospective study is to report 12month outcomes of patients who underwent CAS with CGuard (Inspire MD, Tel Aviv, Israel) microNET self-expanding stent with embolic protection system in a tertiary center from October 2018 to March 2022. Primary endpoints included in-stent restenosis >70% verified by ultrasound (DUS), ipsilateral transient ischemic attack (TIA), and stroke at 12months. Secondary endpoints included cardiovascular-related mortality (stroke, myocardial infarction, heart failure) and all-cause mortality during follow-up. One hundred thirteen patients were included in the study (male 72.5%), symptomatic 47.8%. Median follow-up was 25months (2-48). By 12months, there was one in-stent occlusion that manifested as stroke (1/113, 0.8%) but no other forms of in-stent restenosis. Two patients experienced contralateral TIA (1.7%). CVRM was 3.5% (4 MI) and all-cause mortality was 6% at follow-up. This prospective study shows that CAS with CGuard MicroNET-covered stent is safe with minimal neurological adverse events at 12months follow-up. Larger, and longer-term studies are necessary to define CGuard long-term safety and protection against carotid-related stroke.

An [formula omitted] finite element method for a two-dimensional singularly perturbed boundary value problem with two small parameters

We consider a singularly perturbed boundary value problem, of reaction–convection–diffusion type with two small parameters, and the approximation of its solution by the hp version of the Finite Element Method on the Spectral Boundary Layer mesh. We show that the method converges uniformly, with respect to both singular perturbation parameters, at an exponential rate when the error is measured in the energy norm. Numerical examples illustrating our theoretical findings are also included.

The Dual Role of the Airway Epithelium in Asthma: Active Barrier and Regulator of Inflammation.

Chronic airway inflammation is the cornerstone on which bronchial asthma arises, and in turn, chronic inflammation arises from a complex interplay between environmental factors such as allergens and pathogens and immune cells as well as structural cells constituting the airway mucosa. Airway epithelial cells (AECs) are at the center of these processes. On the one hand, they represent the borderline separating the body from its environment in order to keep inner homeostasis. The airway epithelium forms a multi-tiered, self-cleaning barrier that involves an unstirred, discontinuous mucous layer, the dense and rigid mesh of the glycocalyx, and the cellular layer itself, consisting of multiple, densely interconnected cell types. On the other hand, the airway epithelium represents an immunologically highly active tissue once its barrier has been penetrated: AECs play a pivotal role in releasing protective immunoglobulin A. They express a broad spectrum of pattern recognition receptors, enabling them to react to environmental stressors that overcome the mucosal barrier. By releasing alarmins-proinflammatory and regulatory cytokines-AECs play an active role in the formation, strategic orientation, and control of the subsequent defense reaction. Consequently, the airway epithelium is of vital importance to chronic inflammatory diseases, such as asthma.

Costal margin injuries and trans-diaphragmatic intercostal hernia: Presentation, management and outcomes according to the Sheffield classification.

Costal margin rupture (CMR) injuries are under-diagnosed and inconsistently managed, while carrying significant symptomatic burden. We hypothesized that the Sheffield Classification system of CMR injuries would relate to injury patterns and management options. Data were collected prospectively between 2006 and 2023 at a major trauma center in the United Kingdom. Computed tomography scans were interrogated and injuries were categorized according to the Sheffield Classification. Clinical, radiologic, management and outcome variables were assessed. Fifty-four patients were included in the study. Intercostal hernia (IH) was present in 30 patients and associated with delayed presentation ( p = 0.004), expulsive mechanism of injury (i.e. such as occurs with coughing, sneezing, or retching), higher body mass index ( p < 0.001), and surgical management ( p = 0.02). There was a bimodal distribution of the level of the costal margin rupture, with IH Present and expulsive mechanism injuries occurring predominantly at the ninth costal cartilage, and IH Absent cases and other mechanisms at the seventh costal cartilage ( p < 0.001). There were correlations between the costal cartilage being thin at the site of the CMR and the presence of IH and expulsive etiology ( p < 0.001). Management was conservative in 23 and surgical in 31 cases. Extrathoracic mesh IH repairs were performed in 3, Double Layer Mesh Repairs in 8, Suture IH repairs in 5, CMR plating in 8, CMR sutures in 2, and associated Surgical Stabilization of Rib Fractures in 11 patients. There was one postoperative death. There were seven repeat surgical procedures in five patients. The Sheffield Classification is associated statistically with presentation, related chest wall injury patterns, and type of definitive management. Further collaborative data collection is required to determine the optimal management strategies. Therapeutic/Care Management; Level III.

Facile Electrochemical Biosensing Platform Based on Laser Induced Graphene/Laccase Electrode for the Effective Determination of Gallic Acid

In this study, a facile electrochemical biosensing platform was fabricated with Laccase (Lac) immobilized on laser-induced graphene (LIG) electrode by glutaraldehyde covalently binding for the effective determination of gallic acid (GA). The patterned graphene for the LIG electrode was prepared by a one-step laser direct writing on the polyimide film in ambient air. The sheet layer and spatial mesh structures of LIG give the prepared LIG electrode a large specific surface area and good conductivity. The oxygen enrichment and good hydrophilicity cause LIG to favor covalent crosslinking with laccase through glutaraldehyde. The electrochemical sensor of GA on the prepared electrode was determined by chronoamperometry. Results show that the current signals of the laccase electrodes had an excellent linear relationship with GA in the concentration range of 0.1–20 mmol/L with a detection limit of 0.07 mmol/L under optimized experimental conditions. The prepared GA sensor with good selectivity, regeneration, and stability can be applied to biological samples such as sweat, urine and serum without needing sample pretreatment.