Planar Surface Research Articles

Latent Thermal Energy Storage for Cooling Demands in Battery Electric Vehicles: Development of a Dimensionless Model for the Identification of Effective Heat-Transferring Structures

Thermal energy storage (TES) systems open up alternative paths for air conditioning to increase the range of battery electric vehicles (BEVs) by reducing power consumption. The central prerequisites for this purpose are high storage densities: high-temperature TES systems are being focused on for heat demands, while effective solutions for cooling are missing. Due to their lower temperature potentials, concepts with high storage capacities and heat transports between the storage and cold transferring medium are needed. Latent TES systems based on water enable these capacities but require adequate internal structures for effective heat transfer. Due to the large number of geometric options, high simulation efforts must be conducted to identify favored structures, or the possible design space must be limited for investigations. For this purpose and for the first time, an alternative way is presented using newly developed dimensionless models in a top-down methodology for time-efficient design studies and evaluations. These models were successfully validated and used as a design tool to identify effective structures in latent TES systems for cooling demands in BEVs. A wide array of variation studies on tube, finned plate and novel Triply Periodic Minimal Surface (TPMS) structures were performed and uniformly evaluated with regard to storage densities, cooling efficiencies and geometry. The results show high storage densities for novel TPMS structures, including the enclosure of 100 Wh/kg or 102.2 kWh/m3 with average cooling capacities of 1 kW over 30 min, confirming the usability of latent TES systems in terms of compactness and efficiency for cooling demands in BEVs.

Microstructure and Properties of Al Foil Wrapped AZ31 Plate Prepared by Hot Pressing and Annealing

In this work, an Al foil wrapped AZ31 plate was fabricated by direct hot pressing with a thickness reduction of 50% at 300 °C. Effective metallurgical bonding was produced at the Mg/Al interface and no obvious defects were found. Annealing treatment at 400 °C can generate two continuous intermetallic compound layers (Al3Mg2 on the Al side and Mg17Al12 on the Mg side) at the bonding interface. As annealing time increases, the intermetallic compound layers thicken, accompanied by the thinning and disappearance of the pure Al layer. After annealing for 8 h, a thick coating with the Al3Mg2 and Mg17Al12 mixture is formed on the surface of Mg plate. The micro-hardness of the intermetallic compound layers is much higher than that of the AZ31-substract and pure aluminum layer. Thus, the prolonged annealing (>4 h) can greatly increase the surface hardness. Compared with the as-received AZ31 sample, the corrosion resistance of the Al foil wrapped AZ31 plate can also be greatly improved. As annealing time increased from 0.5 to 8 h, the corrosion resistance showed a slightly decrease. In the present work, the sample annealed for 4 h gave the best consideration to surface hardness and corrosion resistance.

Double-Oxidant-Induced Slurry Reaction Mechanism and Performance on Chemical Mechanical Polishing of 4H-SiC (0001) Wafer.

Single-oxidant slurries are prevalently utilized in chemical and mechanical polishing (CMP) of 4H-SiC crystal. Nevertheless, it is a challenge to achieve a high material removal rate (MRR) and surface quality using single oxidant slurries to meet the needs of global planarization and damage-free nanoscale surface processing of SiC wafers. To solve this challenge, a novel method is proposed for SiC CMP processing using the double oxidant slurry. This slurry mainly consists of alumina (Al2O3) abrasive particles, potassium permanganate (KMnO4), potassium persulfate (K2S2O8), and deionized water. Post CMP, MRR is 1045 nm/h calculated by scratch method, and surface roughness Sa is 0.33 nm measured by 3D optical surface morphometer, with the measurement area of 868 μm × 868 μm. Both the MRR and Sa are far better than those under the single oxidant slurry condition. CMP mechanism with double-oxidant slurry conditions is elucidated by energy dispersive spectrometer and X-ray photoelectron spectrometer. Initially, the Si-C bond on the SiC wafer surface was oxidized by KMnO4, then MnO2 as the reduction product of KMnO4 can also catalyze the S2O82- to further oxidize SiC wafer surface, and eventually the oxidation layers were removed by mechanical action of nano-Al2O3 abrasive particles during CMP processing. These findings offer a pioneering approach and novel perspectives to achieve a higher MRR of 4H-SiC CMP, with potential implications for the application in high-performance SiC devices.

Minimal Impact Pokes to Place Objects on Planar Surfaces

Minimal Impact Pokes to Place Objects on Planar Surfaces

The effect of surface flow conditions on WEPP interrill erodibilities

The Water Erosion Prediction Project erosion model (WEPP) was developed as an event-based more process-based replacement for Universal Soil Loss Equation (USLE) based models in predicting soil erosion as a guide to conserving soil in the USA. However, WEPP has not been shown to predict event soil losses for bare fallow USLE plots better than USLE-based models when stipulated input values have been used. To some extent, this problem can be attributed to the availability of more refined and site-specific input parameters for the USLE-based models. This is true with respect to WEPP’s capacity to model raindrop-driven erosion on USLE plots under natural rainfall. Stipulated values for WEPP interrill erodibilities in the USA were determined only for ridge side slopes but USLE-based models focus on the prediction of long-term average annual soil loss caused by both sheet and rill erosion on planar surfaces. The interrill erodibilities determined for ridge side slopes did not correlate well with those on adjacent flat surfaces sloping along the land slope under the same rainfall conditions. Surface flow conditions, particularly flow depth, differ between the short high gradient side slopes associated with ridges, and the lower gradient slopes in interrill and sheet erosion areas on USLE plots. Failure of WEPP to account for the influence of different flow conditions between ridged and flat areas on raindrop-driven erosion affects the veracity of WEPP to predict average annual soil loss on USLE plots under natural rainfall and the use of WEPP to act as a replacement for USLE based models as an aid to make land management decisions to conserver soil in the USA.

Design of freeform elements with a large exit pupil for AR display

This work presents an augmented reality display consisting of two freeform lenses. The first lens is composed of two aspherical polished surfaces and one plane surface, while the second lens acts as a compensator to allow distortion-free viewing of the surrounding area. One benefit of this design is the large size of the exit pupil, reaching up to 12mm, and the low distortion value of 1.63%. The optics has a thickness of 22mm and is compatible with 0.49-inch diagonal displays. The field of view is limited to 28◦, which is sufficient for various augmented reality applications.

Influence of arc energy on the microstructure and corrosion behavior of ER2209 duplex stainless steel deposited on Q345B low-alloy steel by GMAW

In order to eliminate the complex effects of thermal cycling and the thermal effects of the next pass on multi-layer multi-pass welding of low-alloy steel and duplex stainless steel, ER2209 welding wire was single-layer single-pass deposited on the surface of Q345B hot-rolled plate by gas metal arc welding (GMAW). The microstructure and corrosion resistance of welded joints were studied by different arc energies. The results showed that the arc energy had a significant impact on the “tongue-shaped” morphology and the width of heat affect zone in the welded joint, which in turn affected the corrosion performance of the welded joints. Due to the least distribution of “tongue-shaped” morphology and minimum width of heat affected zone in the welded joint with arc energy of 0.645kJ/mm, it owned the best corrosion resistance. The weld metals of the welded joints were composed of ferrite and austenite phases. The ferrite phases were distributed along grain boundaries and intergranular. As the heat input increases, the distribution of ferrite phase along grain boundaries gradually decreased. The corrosion products and corrosion morphology of the welded joint were also investigated and the corrosion mechanism was discussed in detail. The research results of this article provide a theoretical basis for improving the corrosion performance of multi-layer multi-pass welded joints of low-alloy and duplex stainless dissimilar steels.

Micro-scale modeling and analysis on material removal mechanisms for flexible ball-end tool polishing incorporating the curvature effect

Optical freeform surfaces (OFS) have been extensively employed as core components in advanced optical systems for their excellent performances. However, the surface complexity and the high surface accuracy do impose challenges to the processing of OFS, especially the surface form maintaining or control during polishing. As one of the promising ultra-precision machining technologies to fabricate OFS, the flexible ball-end tool (FBET) polishing becomes available due to its attractive technical advantages. Nevertheless, there are still lack of more comprehensive insights on material removal mechanisms for FBET polishing incorporating the curvature effect, particularly from a microscopic scale, which is of great significance to determine the surface quality and form control in ultra-precision polishing process. In this paper, different from those published macro-scale Preston law-based models, a micro-scale material removal model is developed based on the mutual interaction of the slurry, polishing pad and curved workpiece among the FBET polishing interfaces with micro-contact theory and tribology theory, wherein various parameters embodied in FBET polishing are formulated quantitatively, such as slurry characteristics, pad properties, tool features, processing conditions, as well as workpiece curvature effect. The FBET is designed and adopted to conduct the spot polishing experiments within the concave curvature radius range from 75 mm to 225 mm, wherein the curvature radius range from 225 mm to 800 mm is theoretically chosen as an extension of this research. The predicted results agree well with the experimentally measured section profiles of polishing spots, thereby demonstrating the correctness and effectiveness of the proposed model. Furthermore, the effective relative velocity U together with the separation gap d between reference plane and workpiece surface are known as the two key parameters to account for the material removal mechanisms, and the latter is figured out to be the sensitive one to the curvature effect rather than the former. Through the analysis of key parameters, the established model is capable of helping to strengthen the understanding of material removal mechanisms for FBET polishing with the consideration of curvature effect, addressing those cannot be interpreted by the classical Preston equation previously, which is meaningful for precision control of material removal during polishing of OFS.

A novel green CeO2 polishing slurry and its chemical mechanical action mechanism for achieving atomic-level smoothing of fused silica glass surfaces

Pitch-based tools are integral to computer-controlled optical surfacing (CCOS) for polishing fused silica but face limitations such as low material removal rates (MRR) and challenges in achieving atomic-level smoothing while ensuring environmental sustainability. While chemical mechanical polishing (CMP) excels in processing planar surfaces, it struggles with complex freeform geometries. CCOS addresses this gap with specialized tool head designs that enable precise machining of intricate surfaces. This study introduces an eco-friendly CeO2-based polishing slurry suited for CCOS with pitch tools. By incorporating green reagents, such as polyethylene glycol (PEG) and ethylene glycol (EG), and minimizing harmful chemical usage, the slurry achieves significant breakthroughs in performance. Experimental results reveal a surface roughness (Sa) of 0.075nm, meeting atomic-level smoothing standards, alongside an MRR of 40.5 μm /h, marking substantial improvements over traditional methods. Physicochemical analyses of the CeO2 abrasives, including particle size, morphology, and Ce element content, revealed that abrasives with sharp edges and high Ce content are key factors for obtaining high surface quality and MRR. Molecular dynamics (MD) simulations highlight the synergistic effects of the components, optimizing chemical-mechanical interactions to enhance surface quality. These findings demonstrate the potential of green polishing technologies in advancing the precision machining of fused silica, particularly for complex geometries. The study provides a sustainable and high-performance solution for achieving atomic-level smoothing, paving the way for broader applications in precision optics.

Non-Newtonian rivulet-flows on unsteady heated plane surface

Non-Newtonian rivulet-flows on unsteady heated plane surface

Adaptive Model Compression for Steel Plate Surface Defect Detection: An Expert Knowledge and Working Condition-Based Approach

Adaptive Model Compression for Steel Plate Surface Defect Detection: An Expert Knowledge and Working Condition-Based Approach

Interaction of Kerguelen and Amsterdam-St. Paul dual hotspots with Southeast Indian Ridge

We investigated the influence of the Kerguelen (K) and Amsterdam-St. Paul (ASP) dual hotspots on mantle evolution and crustal accretion in the eastern Indian Ocean. Using surface plate motion constraints from the global plate reconstruction model and the 3-D mantle convection code (ASPECT), we illustrated detailed processes of mantle upwelling, melting, and crustal accretion in the ridge-dual hotspot system. Model results demonstrate that the K hotspot significantly increased the mantle temperature over a wide region of over 1,500 km, leading to a 1–2 km increase in average crustal thickness along the entire Southeast Indian Ridge (SEIR). Only ridge-dual hotspot interaction models can explain key crustal variations along the SEIR. Gravity analysis revealed the K hotspot's long-term interaction with nearby ridges formed significant crustal anomalies, while the ASP hotspot's 10 Myr interaction with SEIR created localized anomalies. The distance between the ridge and hotspot, as well as plume flux, are key factors controlling the strength of ridge-hotspot interaction. The K hotspot, with its relatively higher plume flux, has double the influence distance of the ASP hotspot. Furthermore, our models indicate a possible direct interaction between the K and ASP hotspots, resulting in the ASP plume materials flowing towards the K plume.

Biofouling changes the settling dynamics of macroplastic plates

Plastic pollution transported in rivers remains poorly understood due to the diversity of shapes, sizes, and densities of plastics, as well as their complex interactions with biofilms. While previous studies have explored the settling velocities of plastics and their interactions with biofilms, they often overlook how biofouling alters plastic dynamics and settling behaviour. To address this, over 800 settling experiments were conducted to demonstrate that the dynamics and falling velocities of isotropic (spheres) and anisotropic (square and rectangle plates) macroplastics of different densities (1050 to 2200 kg/m3) are significantly impacted by biofouling. Three-dimensional tracking of plastic trajectories revealed that biofilm colonisation on the surface of anisotropic plastic plates triggered them to exhibit more chaotic trajectories, larger horizontal dispersion and higher oscillatory frequencies. These dynamics reduced the average vertical settling velocity of anisotropic biofouled plates by up to 12%—despite greater plastic densities and considering the multimodal distribution of a plate’s fall velocity—compared to their pristine counterparts. Results highlight the necessity of accounting for the intricate multimodal settling dynamics of plastics, including their interactions with biofilms, to provide more reliable predictions of plastic transport and fate in aquatic environments.

Unraveling the Environmental Applications of Nanoporous Ultrananocrystalline Diamond Films

In this work, a nanoporous ultrananocrystalline diamond film (B-UNCDWS/TDNT/Ti) was obtained and compared with a commercial electrode in the degradation of methomyl, a recalcitrant pesticide. The morphological and structural differences between the materials were highlighted by SEM and XRD analysis: while the commercial electrode presented a regular and planar surface with microcrystalline grains, supported by XRD features, the B-UNCDWS/TDNT/Ti electrode presented a porous morphology with DRX features indicating a high film renucleation rate. Those differences affected the electrooxidation of methomyl; B-UNCDWS/TDNT/Ti was responsible for faster and more economic degradation of the pollutant, achieving a methomyl degradation of 78% (against 35% by the commercial electrode). The highly porous surface of UNCDWS/TDNT/Ti provides an electrochemical area threefold greater than the one found in the commercial electrode, justifying the better efficiency in the formation of persulfate, which can be singled out as the main mechanism in methomyl degradation.

Numerical simulation of temperature in forming surroundings for E-Glass fiber

In spinning, the temperature of the glass melt and the forming surroundings play a crucial role in determining the diameter of the electrical glass (E-glass) filament. It is essential to control or predict the temperature of the forming surroundings. In this study, a simplified cooling model of the fin for G75 E-glass fiber was constructed and simulated to explore the influence of ambient temperature on the forming process of E-glass fiber. The multi-physical field coupling of solid-fluid conjugate heat transferring and surface-to-surface radiation imitates the cooling model. The temperature of the bottom of the bushing plate was measured with an infrared thermal imaging instrument, and the ambient temperature of the area of filament root forming was measured with a thermocouple. Considering the device is fixed, the key experimental variable of the numerical simulation is the distance from the top of the cooling fin to the bottom surface of the bushing plate. The simulated results are compared with the actual measurements, proving that it is feasible for the simplified cooling model to simulate the forming of E-glass fiber. The results of numerical simulations also show that (1) the temperature of the glass melt at the outlet of the nozzle is 1400 K and the ambient temperature of the filament root forming dropped by >500 K; (2) when the top of the cooling fin is 4 mm away from the bottom surface of the bushing plate, the fin has the best cooling effect on the E-glass fiber.

The Rule of Fours-Clinical and Radiographic Parameters for Trans-articular Distal Interphalangeal Joint Kirschner Wire Insertion.

Distal phalangeal and interphalangeal joint injuries are common, and confer a significant burden to the individual, healthcare system and society. Operative intervention (when required) may involve retrograde trans-articular Kirschner wire (K-wire) fixation. Safe wire passage through the center of the distal interphalangeal joint (DIPJ) and associated phalanges is key in maintaining alignment and reducing complications. There is little evidence to guide optimal wire entry point and passage. The aim of this study was to determine soft tissue and radiographic landmarks to guide optimal trans-articular k-wire placement at the DIPJ. A retrospective cohort study was conducted at a single institute, with 100 uninjured lateral phalangeal radiographs with a clear sagittal projection assessed by 3 independent assessors. Each assessor drew a line of ideal insertion, traversing the isthmus of the middle and distal phalanges, and the midline of the DIPJ, with soft tissue and bony parameters identified. The mean distance from the dorsal aspect of the nail plate to the line of ideal insertion was 3.86 mm, with a disparity between sexes noted. The distance from the dorsum of the soft tissue to the line of ideal insertion was expressed as a proportion of the total soft tissue diameter-the line of ideal insertion traversed approximately 40% of total width at the DIPJ and DIPJ soft tissue crease. The results suggest that a simple 'rule of fours' can be utilized to allow expedient and optimal passage. The entry point should be midline in the coronal plane, approximately 4 mm volar to the dorsal surface of the nail plate and aimed at a point 40% volar to the dorsal aspect of the soft tissue envelope at the level of the DIPJ crease. These guidelines are easily replicable and conveyable; additionally, they can guide insertion in the absence of fluoroscopy.

A simple model for faceted topographies at normal faults based on an extended stream-power law

Abstract. Mountain fronts at normal faults are often faceted in the sense that they contain strikingly planar surface elements that follow the surface trace of the fault. Since the dip angle of the facets is typically much lower than the dip angle of the fault, it is clear that the facets are not just the exhumed footwall but have been eroded considerably. It has also been shown that a constant erosion rate in combination with a constant rate of displacement can explain the occurrence of planar facets. Quantitatively, however, the formation of faceted topographies is still not fully understood. In this study, the shared stream-power model for fluvial erosion and sediment transport is used in combination with a recently published extension for hillslopes. As a major theoretical result, it is found that the ratio of the tangents of the facet angle and the dip angle of the fault as well as the ratio of the baseline length and horizontal width of perfect triangular facets mainly depend on the ratio of the horizontal rate of displacement and the hillslope erodibility. Numerical simulations reveal that horizontal displacement is crucial for the formation of triangular facets. For vertical faults, facets are rather multiangular and much longer than wide. While the sizes of individual facets vary strongly, the average size is controlled by the ratio of hillslope erodibility and fluvial erodibility.

Experiments and numerical simulations on fatigue properties of laser shock peening for FV520B steel

Laser shock peening (LSP) experiments, low cycle fatigue experiments, microhardness and residual stress measurements, and scanning electron microscopy (SEM) analyses were conducted on FV520B steel cylindrical specimens. Additionally, ABAQUS software was employed to predict fatigue life following the LSP process. The experimental results indicate that the surface compressive residual stresses induced by LSP inhibit both the initiation and propagation of fatigue cracks effectively, thereby prolonging the fatigue life of FV520B steel. The fatigue life of specimens at strain amplitudes of ± 0.5 %, ±0.6 %, ±0.7 %, and ± 1.0 % is improved by 132.2 %, 0.4 %, 18.0 %, and 88.8 %, respectively. A residual stress of −90 MPa is measured on the surface of the specimen and the surface hardness value increase by 48 % after LSP. The SEM results reveal that the characteristic of single crack sources for crack initiation is presented after LSP. The results of single point LSP simulation using ABAQUS demonstrate that the circumferential surface experiences a lower compressive residual stress of 30 MPa compared to a higher value of 45 MPa on the planar surface, this discrepancy arises due to rapidly decay associated with reduced rebound tensile strain on convex surfaces. A “multi-point continuous shock” simulation strategy was implemented for modeling LSP effects on the circumferential surface. The average compressive residual stress achieved was found to be 92 MPa, additionally, tensile residual stresses ranging from 8 MPa to 29 MPa were detected within secondary surfaces and inside the cylinder. Notably, discrepancies between simulated and experimental fatigue lives for LSP specimens across strain amplitudes of ± 0.5 %, ±0.6 %, ±0.7 %, and ± 1.0 % were minimal-ranging only between 10.4 % and 22.3 %.

Conic sections in ferroelectric nematics: Experiments and mathematical modeling

The domain structure of a fluid ferroelectric nematic is dramatically different from the domain structure of solid ferroelectrics since it is not restricted by rectilinear crystallographic axes and planar surface facets. We demonstrate that thin films of a ferroelectric nematic seeded by colloidal inclusions produce domain walls (DWs) in the shape of conics such as a parabola. These conics reduce the bound charge within the domains and at the DWs. An adequate description of the domain structures requires one to analyze the electrostatic energy, which is a challenging task. Instead, we demonstrate that a good approximation to the experimentally observed polydomain textures is obtained when the divergence of spontaneous polarization—which causes the bound charge—is heavily penalized by assuming that the elastic constant of splay in the Oseen-Frank energy is much larger than those for twist and bend. The model takes advantage of the fact that the polarization vector is essentially parallel to the nematic director throughout the sample. Published by the American Physical Society 2024

Critical adsorption of polyelectrolytes onto highly oppositely charged surfaces: Effects of charge renormalization.

The critical adsorption conditions of polyelectrolytes (PEs) onto planar, cylindrical, and spherical surfaces were obtained by solving the Edwards equation using the Wentzel-Kramers-Brillouin (WKB) method. It demonstrated to provide a suitable analytical approach for all three geometries, in conformity with some experimental results for weakly charged micelles. However, our Monte Carlo simulations implementing approximate solutions of the nonlinear Poisson-Boltzmann equation for highly charged surfaces indicated recently the emergence of a limiting value of ionic strength due to a nonlinear dependence of the electrostatic (ES) potential on the surface-charge density σ. Beyond this limiting ionic strength, the PE adsorption no longer occurs, shifting the standard paradigm. In this work, we employ the concept of a renormalized charge and use the WKB method to study the effects of this nonlinearity on the critical adsorption conditions, density profile, and adsorbed layer of PE segments, all in comparison with the results of the linear Debye-Hückel (DH) approach. Charge renormalization makes it possible to use the known WKB solutions in the DH regime also for surfaces with high σ, introducing a saturation effect observed in the nonlinear case. The larger ES screening affects the density profile and the adsorbed layer of PEs, promoting a more dispersed distribution of PEs at higher surface-charge densities. Our analytical results for the critical adsorption curve reproduce the limiting ionic strength for high σ and also recover the DH regime at low σ.