Actual Surface Research Articles

Multi-scale calibration of a non-hydrostatic model for wave runup simulation

Modeling wave runup on beaches and structures is an important step toward accurate coastal flood prediction. Depth-averaged non-hydrostatic models such as XBNH (XBeach Non-Hydrostatic) are computationally cost-effective yet accurate tools to numerically simulate random wave runup. XBNH includes a number of calibration parameters, which are determined on a case-study basis. This study aims to investigate the range of XBNH input parameters that results in accurate predictions regardless of the application scale, benefiting future applications of XBNH that lack the measurements needed for model calibration. The study performs calibration and sensitivity analysis to investigate the model response to the input parameters for applications with different spatial scales, including small- and large-scale laboratory wave runup experiments and a real-scale field experiment. A Grid search method is utilized to perform a multi-scale calibration of the input parameters used in the parametrization of the wave breaking process in XBNH. The effect of parameters in the JONSWAP spectrum used to generate the offshore boundary conditions is investigated. Results show that using a single combination of calibrated input parameters, the model is able to capture random wave runup on beach, beach-dune, and beach-seawall systems with various spatial scales. Moreover, wave spectrum parameters can highly influence the model performance, and calibration of these parameters makes the model more robust to replicate the actual water surface fluctuations.

Effectiveness of a combined UV-C and ozone treatment in reducing healthcare-associated infections in hospital facilities

Hospital-acquired infections pose an ongoing threat to patient safety due to the presence of multi-drug-resistant organisms (MDROs) and other pathogens such as Clostridioides difficile which are dependent on thorough and effective cleaning and disinfection by personnel. This study evaluated the influence of UV-C air treatment: the air in the room was sanitized by UV-C and redirected into the room. In addition, ozone was released into the room to treat actual surfaces in low-risk areas such as hospital gyms, and high- to medium-risk areas such as hospital rooms. To this aim, a portable device designed for treating the environment air was tested against nine bacterial strains including Aspergillus spp. and Clostridioides spp. The use of UV-C air treatment during daily operations and ozone treatment achieved at least a 2-log10 pathogen reduction except for Clostridioides spp. Effective prevention of C.difficile normally requires the use of combined approaches that include chemical compounds and disinfection agents whose toxicity can be harmful not only to patients but also to healthcare personnel. Thus, the proposed no-touch device may be evaluated in future research to assess the needed requirements for its possible and full implementation in hospitals.

Arduino-Based Low-Cost Device for the Measurement of Detonation Times in Blasting Caps.

The use of equipment such as oscilloscopes, high-speed cameras or acoustic sensors is quite common to measure detonation times from surface connectors and detonators. However, these solutions are expensive and, sometimes, not adequate to use in field conditions, such as mining or civil works. In this regard, a low-cost portable device is designed and tested using the Arduino platform, achieving a simple, robust and precise system to carry out field measurements. This study describes the characteristics and working principles of the designed device, as well as the verifications carried out to check the accuracy of the Arduino ceramic oscillator. Additionally, a field test was carried out using 100 actual detonators and surface connectors to verify the correct operation of the designed equipment. We have designed a device, and a methodology, to measure detonation instants with a minimum accuracy of 0.1 ms, being sufficient to carry out subsequent studies of detonation time dispersion for non-electric detonators.

Application of pitch-based multi cavity carbon microsheets in capacitive deionization removal of NO3–

Capacities deionization (CDI) denitrification technology has attracted considerable attention, and electrode materials with nitrate adsorption properties have become a research hotspot. In this study, a multi cavity carbon microsheets (MCCM-5) was prepared using a hard template method and low-cost nitrated pitch as a carbon source. The results of the electrosorption experiments showed that the material had an excellent capacity of NaNO3 (45 mg g−1). Furthermore, although the actual specific surface area and specific capacitance of MCCM-5 are lower than those of hierarchical porous carbon materials (HPCM-1), MCCM-5 exhibit lower diffusion and charge-transfer resistances, resulting in a better denitrification performance. The adsorption capacity of MCCM-5 for NaNO3 was twice that HPCM-1 and 11.8 times that of commercial activated carbon, which is superior to the material properties reported thus far. Our analysis indicated that the material combined the advantages of both a layered structure and hierarchical pores. First, the uniformly distributed hierarchical pores in the layered structure enhanced the ion concentration potential. Second, the layered structure provided good ion diffusion channels, thereby increasing the effective adsorption area of the material. DFT calculation shows that the carbon cavity structure enriched in the material shows a stronger adsorption capacity for NO3–, which can promote the electron transfer process during NO3– adsorption. This study shows that a precise regulation of the carbon material structure can be achieved by adjusting the size of the template material and carbonization conditions to obtain a higher adsorption capacity and provides a new idea for the structural optimization of electrode materials.

Hidden mysteries in ancient Egyptian paintings from the Theban Necropolis observed by in-situ XRF mapping.

The material study of ancient Egyptian paintings began with the advent of Egyptology during the 19th century. By the 1930s, a lot had already been sampled and described. The limited palette for example has been analysed from actual painted surfaces but also from pigments and painting tools retrieved on site. However, most of these studies took place in museums while the painted surfaces, preserved in funerary chapels and temples, remained somewhat estranged from this primary physical understanding. The artistic process has been also reconstructed, mainly from the information presented by unfinished monuments, showing surfaces at different stages of completion. A lot of this modern and theoretical reconstruction is, however, based on the usual archaeological guessing game that aims at filling the remaining blanks. Our interdisciplinary project has decided to experiment on-site with state-of-the-art portable analysis tools, avoiding any physical sampling, to see if our knowledge of the work of the ancient Egyptian painters and draughtsmen could be taken at a further stage, while based on physical quantification that could be seen as a stronger and more reliable foundation for a redefined scientific hypothesis. The use of XRF mapping has, for instance, been applied to a known case of correction by surface repaint, something that is supposedly rare in the ancient Egyptian formal artistic process, while another fully unexpected one was discovered during the analytic exploration of a royal representation. In both cases, the precise and readable imaging of the physical composition of the painted surface offers a renewed visual approach based of chemistry, that can be shared through a multi- and interdisciplinary approach. However, this also leads to a more complex description of pigment mixtures that could have multiple meanings, where the practical often leads towards the symbolic, and from there hopefully to a renewed definition of the use of colours in complex sets of ancient Egyptian representations. At this stage, though the progress in this on-site material assessment of ancient works of art definitely means astonishing progress, one humbly has to face the fact that these ancient treasures shall still retain part of their defining mysteries.

Environment-Induced Crack Initiation in Aluminum Alloys: Experimental Studies Since the 1950s and Future Opportunities

The initiation of environment-induced cracking (EIC) in aluminum alloys typically dominates the total life during both service-life for structural applications and for smooth tensile test specimens subjected to conventional standard EIC testing. Experience and literature published over the past 70 y have been reviewed, and in some cases re-interpreted. The authors propose we are now well-positioned to use today’s advanced experimental techniques to properly elucidate the EIC initiation phenomena for aluminum alloys. EIC initiation typically involves at least three stages: incubation, intergranular cracking that may “arrest” and a transition to propagating cracks where the mechanical driving force exceeds a threshold, KIEIC, and a surface feature that has become a crack potentially propagating at mm/y. Alloy developers, product designers, and commercial users now need quantitative EIC initiation and growth data from accelerated laboratory testing that is directly relatable to actual surface conditions and the expected service conditions.

Manufacturing error and misalignment effect on the transient lubrication behavior of dynamically loaded journal bearing with micro-groove

The novelty of this paper is to numerically investigate the effect of manufacturing error and misalignment on the transient lubrication behavior of dynamically loaded journal bearings with micro-groove. Based on the average Reynolds equation considering the mass conservation cavitation algorithm, the asperity contact model, and the force balance equation, the mixed lubrication model under time-varying dynamic loads is developed. Meanwhile, mathematical functions are given for the bearings with different surface profiles, including the circumferential and axial manufacturing errors of the bearing, the horizontal and vertical deflection angles of the journal, and the micro-grooves with different distribution forms. According to this model, the lubrication characteristics of the bearing are systematically investigated at different horizontal and vertical deflection angles, amplitudes, spatial numbers, and phase angles of the circumferential waviness, as well as shape profiles of the axial error. In addition, the performance parameters of dynamically loaded journal bearings with ideal and actual surfaces under different micro-groove distributions are comparatively evaluated. Numerical results show that manufacturing errors and misalignment have a remarkable effect on the transient behavior of dynamically loaded journal bearings, and the coupling effect will be more consistent with practical engineering. It can be found that the distribution form of the micro-groove surface directly affects the friction reduction effect of bearing systems. The numerical model can serve as a meaningful guideline for the optimum design of dynamically loaded journal bearing with micro-groove.

Comprehensive Surface Histology of Fresh Resection Margins With Rapid Open-Top Light-Sheet (OTLS) Microscopy.

For tumor resections, margin status typically correlates with patient survival but positive margin rates are generally high (up to 45% for head and neck cancer). Frozen section analysis (FSA) is often used to intraoperatively assess the margins of excised tissue, but suffers from severe under-sampling of the actual margin surface, inferior image quality, slow turnaround, and tissue destructiveness. Here, we have developed an imaging workflow to generate en face histologic images of freshly excised surgical margin surfaces based on open-top light-sheet (OTLS) microscopy. Key innovations include (1) the ability to generate false-colored H&E-mimicking images of tissue surfaces stained for < 1 min with a single fluorophore, (2) rapid OTLS surface imaging at a rate of 15 min/cm2 followed by real-time post-processing of datasets within RAM at a rate of 5 min/cm2, and (3) rapid digital surface extraction to account for topological irregularities at the tissue surface. In addition to the performance metrics listed above, we show that the image quality generated by our rapid surface-histology method approaches that of gold-standard archival histology. OTLS microscopy has the feasibility to provide intraoperative guidance of surgical oncology procedures. The reported methods can potentially improve tumor-resection procedures, thereby improving patient outcomes and quality of life.

A Kind of Water Surface Multi-Scale Object Detection Method Based on Improved YOLOv5 Network

Visual-based object detection systems are essential components of intelligent equipment for water surface environments. The diversity of water surface target types, uneven distribution of sizes, and difficulties in dataset construction pose significant challenges for water surface object detection. This article proposes an improved YOLOv5 target detection method to address the characteristics of diverse types, large quantities, and multiple scales of actual water surface targets. The improved YOLOv5 model optimizes the extraction of bounding boxes using K-means++ to obtain a broader distribution of predefined bounding boxes, thereby enhancing the detection accuracy for multi-scale targets. We introduce the GAMAttention mechanism into the backbone network of the model to alleviate the significant performance difference between large and small targets caused by their multi-scale nature. The spatial pyramid pooling module in the backbone network is replaced to enhance the perception ability of the model in segmenting targets of different scales. Finally, the Focal loss classification loss function is incorporated to address the issues of overfitting and poor accuracy caused by imbalanced class distribution in the training data. We conduct comparative tests on a self-constructed dataset comprising ten categories of water surface targets using four algorithms: Faster R-CNN, YOLOv4, YOLOv5, and the proposed improved YOLOv5. The experimental results demonstrate that the improved model achieves the best detection accuracy, with an 8% improvement in mAP@0.5 compared to the original YOLOv5 in multi-scale water surface object detection.

Reconstruction of a Monthly 1 km NDVI Time Series Product in China Using Random Forest Methodology

The normalized difference vegetation index (NDVI) is one of the most common metrics used to describe vegetation dynamics. Unfortunately, low-quality pixels resulting from contamination (by features including clouds, snow, aerosols, and mixed factors) have impeded NDVI products’ widespread application. Researchers have thought of several ways to improve NDVI quality when contamination occurs. However, most of these algorithms are based on the noise-negative deviation principle, which aligns low-value NDVI products to an upper line but ignores cases where absolute surface values are low. Consequently, to fill in these research gaps, in this article, we use the random forest model to produce a set of high-quality NDVI products to represent actual surface characteristics more accurately and naturally. Climate and geographical products are used as model inputs to describe environmental factors. They represent the random forest (RF) model that establishes relationships between MODIS NDVI products and meteorological products in high-quality areas. In addition, auxiliary data and empirical knowledge are employed to meet filling requirements. Notably, the random forest (RF) algorithm exhibits a mean absolute error (MAE) of 0.024 and a root mean squared error (RMSE) of 0.034, in addition to a coefficient of determination (R2) value of 0.974. Furthermore, the MAE and RMSE of the RF-based method decreased by 0.014 and 0.019, respectively, when compared to those of the STSG (spatial–temporal Savitzky–Golay) plan and by 0.013 and 0.015, respectively, when compared to the LSTM (long short-term memory) method. R2 increased by 0.039 and 0.027, respectively, compared to the STSG and LSTM methods. We introduced a novel series of NDVI products that demonstrated consistent spatial and temporal connectivity. The novel product exhibits enhanced adaptability to intricate environmental conditions and promises the potential for utilization in investigating vegetation dynamics within the Chinese region.

Quantifying interfacial interactions for improved membrane antifouling: A novel approach using triangulation and surface element integration method

To gain a thorough understanding of interfacial behaviors such as adhesion and flocculation controlling membrane fouling, it is necessary to simulate the actual membrane surface morphology and quantify interfacial interactions. In this work, a new method integrating the rough membrane morphology reconstruction technology (atomic force microscopy (AFM) combining with triangulation technique), the surface element integration (SEI) method, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the compound Simpson's approach, and the computer programming was proposed. This new method can exactly mimic the real membrane surface in terms of roughness and shape, breaking the limitation of previous fractal theory and Gaussian method where the simulated membrane surface is only statistically similar to the real rough surface, thus achieving a precise description of the interfacial interactions between sludge foulants and the real membrane surface. This method was then applied to assess the antifouling propensity of a polyvinylidene fluoride (PVDF) membrane modified with Ni-ZnO particles (NZPs). The simulated results showed that the interfacial interactions between sludge foulants in a membrane bioreactor (MBR) and the modified PVDF-NZPs membrane transformed from an attractive force to a repulsive force. The phenomenon confirmed the significant antifouling propensity of the PVDF-NZPs membrane, which is highly consistent with the experimental findings and the interfacial interactions described in previous literature, suggesting the high feasibility and reliability of the proposed method. Meanwhile, the original programming code of the quantification was also developed, which further facilitates the widespread use of this method and enhances the value of this work.

Investigation on surface quality in micro milling of additive manufactured Ti6Al4V titanium alloy

The additive manufactured technology is widely applied to produce titanium alloy parts with complex structures. The subsequent machining operations are necessary for additive manufactured parts to achieve the required machining quality. In this paper, the theoretical surface roughness model in micro milling was established. The model indicated the theoretical milled roughness mainly depends on the feed per tooth, tool nose radius and bottom edge inclination angle. Then, micro milling experiments are conducted on additive manufactured titanium alloy using PCD micro end mill. The surface roughness on milled surface was measured and investigated. At the middle position of micro milled surface, the distribution curves of surface roughness Ra and Sa show the same variation trend under different milling parameters. Moreover, the measured surface roughness results on different transverse positions of milled surface showed that the difference value between the actual and theoretical surface roughness of milled surface is mostly induced by the unstable cutting behaviors, which is also mainly responsible for the surface roughness size effect. The transverse distribution of surface roughness on milled surface exhibited a W shape because of the variation of the instantaneous undeformed chip thickness and material removal mode at different transverse positions.

Silicon electrodeposition from the KF-KCl-K&lt;sub&gt;2&lt;/sub&gt;SiF&lt;sub&gt;6&lt;/sub&gt; and KF-KCl-KI-K&lt;sub&gt;2&lt;/sub&gt;SiF&lt;sub&gt;6&lt;/sub&gt; melts

Silicon and silicon-based materials find extensive applications in metallurgy, microelectronics, and other emerging industries. The field of use of synthesized silicon varies based on its morphology and purity. This study employs voltammetry, galvanostatic electrolysis, and scanning electron microscopy to examine the impact of KI surfactant (in mol %) to 66.5KF–33.3KCl–0.23K2SiF6 melt at 750°C on the electrowinning kinetics of silicon ions and the morphology of silicon deposits formed on a glassy carbon electrode. The findings demonstrate that the addition of potassium iodide to the KF–KCl–K2SiF6 melt at a concentration of 2 mol % induces changes in interfacial tension at the boundary between the glassy carbon, melt, and atmosphere. Consequently, the wetting of the glassy carbon with the melt decreases, leading to a reduction in the actual working surface area and, consequently, a decrease in cathode current while maintaining current density. Taking into account this effect and employing an algebraic estimation of the influence of the melt meniscus shape, it is postulated that the addition of KI does not significantly affect the kinetics of the cathode process. Nevertheless, the impact of KI addition on the morphology of electrodeposited silicon is mentioned. During the electrolysis of the KF–KCl–K2SiF6 melt, fibrous silicon deposits with arbitrary shapes are formed on the glassy carbon electrode, whereas the addition of 2 and 4 mol % of potassium iodide to the melt leads to the agglomeration and smoothing of silicon deposits under the same electrolysis conditions (cathode current density: 0.02 A/cm2, electrolysis duration: 2 h). The obtained results indicate the potential to manipulate the morphology of electrodeposited silicon for specific applications in various fields.

Multiscale characterization and contact performance analysis of machining surfaces

Accurately characterizing the surface topography of parts is crucial to improve the surface measurement accuracy and analyze the surface contact performance. A method is proposed to separate the morphological characteristics of the actual machined surface based on the layer-by-layer error reconstruction method and the signal-to-noise ratio method during the wavelet transform process, so as to evaluate the contact performance of the different joint surfaces. First, the actual machined surface morphological features are separated by using the wavelet transform method, the layer-by-layer error reconstruction method, and the signal-to-noise ratio method. Second, the reconstructed three-dimensional surface contact model is established by the reverse modeling engineering method. Third, the finite element method is used to analyze the impact of processing methods and surface roughness on contact surface parameters. The result demonstrates that the simplified and efficient three-dimensional reconstructed surface is achieved based on the real machining surface in contrast to other existing approaches. The surface roughness has a more significant influence on contact performance. The contact deformation increases with the increase of surface roughness, while the curves of average contact stress, contact stiffness, and contact area have the opposite trend.

A simple slope correction of horizontally measured albedo in sloping terrain

In sloping terrain, albedo measured in the horizontal plane is typically not representative for the underlying surface. Accordingly, albedo should be measured either parallel (termed slope-parallel albedo) or corrected from horizontal measurements (termed slope-corrected albedo) to represent the actual sloping surface. This study presents the theory and the effect when applying a simple slope correction with the aim to transform albedo measured in the horizontal plane over a slope (termed horizontally measured albedo) to the sloping surface. Simultaneous measurements of horizontal and slope-parallel albedo for three different classes of atmospheric clearness conditions (clear, partly overcast, cloudy) and for four different terrain aspects (north, east, west, south) were collected during the study period. The results show that applying the slope correction improved the linear correlation coefficient between the slope-parallel and horizontally measured albedo by 0.60, 0.51 and 0.24 for clear, partly overcast, and cloudy conditions, respectively. During clear atmospheric conditions, slope-parallel and slope-corrected albedo deviated by 5% in terms of mean absolute error, while the slope correction reduced the deviation between the horizontally measured and slope-parallel albedo by 70%. Diurnal trends revealed a large discrepancy with smaller/larger horizontally measured albedo than slope-parallel albedo for the western/eastern slope during morning (opposite during afternoon). For the southern/northern slope the horizontal orientation of the radiation sensors overestimated/underestimated the albedo for all atmospheric clearness conditions. The horizontally measured reflected radiation had on average a difference of 3 Wm-2 from the slope-parallel reflected radiation, corresponding to a deviation of 3%. The findings show that the simple slope correction considerably improve the reliability of the horizontally measured albedo in sloping terrain when slope-parallel measurements are not possible. However, during partly overcast conditions, the simple slope correction suffers under the complex radiation regime and should preferably not be applied.

The liquefaction pressure characteristics of silty soil in the Chengdao area: Numerical simulations

This study employs the Massachusetts Institute of Technology General Circulation Model (MITgcm) to simulate the pressure of liquefied soil during the initial stage of liquefaction in the Chengdao area of the Yellow River delta. Unlike previous studies that simulated the liquefaction process using single waves, this study employs 32 linear waves as driving factors, which is more consistent with the wave conditions on an actual sea surface. By setting the density, viscosity and topography, the simulated pressure can be consistent with the measured pore pressure and soil pressure. The simulation results accurately reflect the pressure characteristics induced by wave groups, indicating that MITgcm's excellent ability to simulate the pressure of liquefied silty soil. By comparison, numerical simulation is more accurate than theoretical formula calculation, and the correspondence between the simulation results and measured pressure highlights the importance of the physical factors considered in the model. These factors represent objective physical laws and play an essential role in the simulation's accuracy and reliability. This study reveals the pressure characteristics of liquified soil induced by wave groups and is expected to provide useful information for offshore engineers and researchers of soil liquefaction.

Gear evaluation deviations-based crucial geometric error identification of five-axis CNC gear form grinding process

The gear form grinding accuracy is significantly affected by crucial geometric errors. The gear form grinding process is a special line contact forming method. There are exclusive evaluation standards for gear grinding accuracy. While the existing sensitivity analysis for spatial point errors cannot meet the final gear report requirements. Hence, a novel method for analysis of geometric error influence on the key gear evaluation deviations (GED) is proposed. First, the actual digital tooth surface considering geometric errors and gear form grinding mechanism was constructed according to the homogeneous transformation matrix (HTM) and multi-body system theory (MBS). Second, the GED of the digital tooth surface was gained according to the modified gear meshing equations. Third, the analytic mapping relationship between the GED and machine tool geometric errors was first established. Then, the crucial geometric errors affecting the GED were identified based on a proposed Morris method. Finally, the identification results were compared to the existing publications, and the compensation discussions of crucial errors were demonstrated to validate the advantages of the proposed method. It can be found that the compensation results of GED-oriented key errors are better than those of the traditional methods, which is beneficial to the improvement of evaluation reports.

Malachite green dye adsorption by jackfruit based activated carbon: Optimization, mass transfer simulation and surface area prediction

The exposure of basic dye towards human and environment can caused severe adverse effects. Hence, this study aimed (i) to optimize the adsorption of malachite green (MG) dye onto jackfruit peel based activated carbon (JPAC) by using response surface methodology (RSM) and (ii) to simulate the mass transfer process using Polymath mass transfer (PMT) model. The RSM revealed that the optimum activation temperature, activation time and potassium hydroxide (KOH) impregnation ratio, IR to be 782 °C, 1 h and 2.96 g/g which translated into 66.80 mg/g of MG adsorption and 34.52 % of JPAC's yield. The Freundlich isotherm model described the adsorption process the best while the Langmuir monolayer adsorption capacity was computed to be 376.33 mg/g. The kinetic data obeyed the PMT model the best where the rate constant, KPMT decreased from 1.20 to 0.41 h−1 as the MG concentration increased from 25 to 300 mg/L. Also, the PMT model was succeeded in predicting the surface area, aPMT of JPAC to be 807.77 m2/g and this value is comparable with the actual JPAC's mesopores surface area of 714.25 m2/g (error 11.58 %). The adsorption of MG onto JPAC was aided by several functional groups such as primary or secondary alcohol, non-bonded hydroxy group and methoxy through ion-dipole force and dipole-dipole force. Based on thermodynamic parameters, MG-JPAC adsorption system was endothermic in nature (∆H° = 37.12 kJ/mol), had an increment of randomness at solid-liquid interface (∆S° = 0.19 kJ/mol·K), spontaneous in nature (−20.11 kJ/mol) and physisorptionally governed (Ea = 9.46 kJ/mol).

Liquid temperature gradient estimation for screen channel liquid acquisition device bubble point tests in liquid nitrogen

The LAD screen utilizes surface tension forces in microgravity environments to allow liquid to flow through the screen while blocking vapor ingestion up to a certain pressure differential across the screen. The limiting pressure differential of LAD screen operation prior to bubble breakthrough is known as the bubble point pressure (ΔPBP). Previous cryogenic ΔPBP studies have identified how noncondensable pressurization decreases the interface temperature within the pores of a LAD screen via evaporative cooling and how autogenous pressurization increases the interface temperature within a LAD screen via condensation heating. The temperature gradient in the liquid side boundary layer near the screen caused by these effects has not been previously quantified. This study provides an order of magnitude analysis to show how certain variables can influence the liquid side temperature gradient during ΔPBP tests in liquid nitrogen (LN2) using noncondensable pressurization. Furthermore, cryogenic LN2ΔPBP data is taken for a 325x2300 Dutch Twill and 200x600 Dutch Twill screen with liquid side temperature measurements collected at varying distances away from the screen using dewar pressures ranging from ∼0-8psig (∼101.3-156.5kPa absolute). It has been shown that measuring the liquid screen side temperature 1/8″ (3.2 mm) away from the screen can result in a liquid side surface tension value that is ∼10-12.5% lower than the actual surface tension value at the interface for GHe tests in LN2. An empirical correlation is provided based on experimental temperature gradient data to correct historical and future ΔPBP data for the liquid screen side diode placement.

Numerical simulation of the residual stress and failure probability of solid oxide fuel cells with nonplanar cathode–electrolyte interfaces

ABSTRACT The actual surface of solid oxide fuel cells exhibits a fluctuating nature. In this study, the residual stresses and failure probability of nonplanar interfaces with different waveforms and wavelengths were investigated using a cosine interface approximation technique to simulate the actual cathode – electrolyte interface. Results showed that the electrolyte was subjected to compressive stresses with a maximum value at the trough. During cell preparation, the anode underwent conversion from an oxidized state to a reduced state, reducing residual stress in the electrode. Increasing the amplitude exerted a significantly greater effect on stress change than decreasing it. When the wavelength is longer, the stress fluctuation is lower. During anode reduction, the cathode reached the highest probability of failure and was damaged when the nickel oxide content exceeded 55%. A minimum anode thickness of 0.6 mm ensured anode stability.