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In fusion‐based metal additive manufacturing (MAM), the high‐intensity energy input leads to serious evaporation, but how evaporation induces composition evolution and variation and further impacts microstructure and mechanical properties remain a knowledge gap. Here a model integrating composition evolution with molten pool dynamics is developed to reproduce temperature‐ and composition‐dependent evaporative losses and subsequent transport during laser melting. Together with comprehensive experimental characterizations and tests, the simulation results illustrate varying evaporation rates of different elements altering compositions, resulting in a 3D cirrus‐shaped concentration distribution, which significantly impacts the mechanical properties. The simulations reproduce the detailed composition evolution from surface evaporation to molten pool transport and reveal underlying mechanisms relating the composition, temperature, fluid flow, and cracking, which is challenging to observe experimentally. This study elucidates the critical role of evaporation‐induced composition evolution in determining microstructure and mechanical properties. In future alloy design for MAM, integrating initial composition and manufacturing parameters is imperative, where composition evolution simulation offers valuable guidance. [ABSTRACT FROM AUTHOR]

High voltage circuit breakers are important equipment in power systems, and the valve motion of the chambers plays a role in the arc extinguishing performance of high-voltage circuit breakers. Therefore, in this paper, a 145 kV auto-expansion SF6 circuit breaker is taken as the research object, and a two-dimensional axisymmetric magnetohydrodynamic arc model considering valve motion process is established. The influence of different short circuit breaking conditions on the valve motion was studied. The results show that the backflow phenomenon of ablated steam is the main reason for the closure of the non-return valve, which plays an important role in opening the pressure relief valve. The closing time of the non-return valve is about 0.4 ms faster at a short circuit current of 40 kA than at a short circuit current of 36 kA. [ABSTRACT FROM AUTHOR]

The C4F7N/CO2 mixed gas is most expected to replace SF6 in high-voltage power equipment, and the generation of free metal particles in gas-insulated equipment is unavoidable and highly susceptible to inducing insulation failures. In this paper, the effects of flaky, spherical, and mixed shape aluminum particle defects on the breakdown characteristics of C4F7N/CO2 mixed gas are investigated and compared to those of SF6 under the same conditions. The experimental results show that the effect of particle defects on the insulating properties of C4F7N/CO2 gas mixtures is visualized by the fact that particle defects reduce the breakdown voltage of C4F7N/CO2 gas mixtures, increase their stochasticity, and reduce the enhancement of the insulating properties of C4F7N/CO2 gas mixtures by increasing the air pressure. The greater the number of particles, the greater is the degree of influence. Comparison of the SF6 and C4F7N/CO2 gas mixtures reveals that, in the case of flake defects, increasing the air pressure improves the insulation performance of the SF6 gas better than that of the C4F7N/CO2 gas mixture. Under the condition of the same number of particles, the larger the proportion of spherical particles in the hybrid particles, the smaller is the influence of metal particles on the C4F7N/CO2 mixed gas and on SF6 gas. [ABSTRACT FROM AUTHOR]

One of the most essential tasks in probabilistic damage tolerance assessment is to describe the scatter in crack growth accurately. This study proposes a stochastic model of the crack growth rate, which calculates the critical parameters of a random distribution accurately by combining the Markov chain and data fitting algorithms. The proposed method is validated by the crack growth test data of Ni‐based superalloy GH4710Li at 550°C. The validation results show that the proposed method is a robust and efficient stochastic model for the crack growth rate. [ABSTRACT FROM AUTHOR]

In this study, a combined low‐ and high‐cycle fatigue (CCF) life prediction model, which considers the crack closure effect (CCE) of micro‐defects, is proposed based on the continuous damage mechanics. The model is decomposed into three submodels: the low‐cycle fatigue (LCF), high‐cycle fatigue (HCF) under the maximum stress of LCF (HCFML), and their coupled damage models. The experimental CCF data of K403 full‐scale turbine blades are used to verify the accuracy. The prediction life falls within the ±2.62 times of scatter band compared with the experimental results. Further, there are the different damage evolution forms at different vibration stresses. When the vibration stress is below 29 MPa, the CCF damage mainly is caused by the LCF. However, while the vibration stress is above 29 MPa, the HCFML damage plays a major role. The CCF damage of the first stage serration of K403 turbine blades is mainly from HCFML. Highlights: New combined low‐ and high‐cycle fatigue (CCF) life prediction model.Consider the crack closure effect of micro‐defects based on the damage mechanics.Evolution laws of damage rate and damage under CCF loads.The main damage to the serrations of turbine blades in the actual external field. [ABSTRACT FROM AUTHOR]

ABSTRACT A combined high and low cycle fatigue (CCF) life prediction model, considering creep, low‐cycle fatigue (LCF), high‐cycle fatigue (HCF) at the maximum LCF nominal stress (HLCF) damages, and the interaction damage between LCF and HLCF, is proposed. The proportions for these four types of damage in total CCF damage are quantified. Compared with the existing CCF models, the CCF model proposed in this paper considers creep damage in CCF and has higher accuracy. The escalation in HCF stress amplitudes leads to reduced CCF life owing to the augmentation of HLCF and interaction damages. The increase in the cycle ratio of HCF to LCF, causing a reduction in CCF life is ascribed to elevated HLCF and creep damages. The calculated damage proportion results from the proposed model are consistent with the observations of the fracture characteristics using a scanning electron microscope (SEM), indicating the necessity of considering creep damage in CCF life prediction at high temperatures. [ABSTRACT FROM AUTHOR]

In this paper, a digital image correlation (DIC) method is developed and applied on film cooling holes in the submillimeter scale in high temperature. Compared with the traditional DIC method, the speckle patterning method and the optical system are improved. In detail, a kind of high temperature-resistant black paint is selected as the basecoat, and the white ZrO2 particles are evenly distributed on the specimen using high-pressure splashing method. Besides, to eliminate the radiation effect of the high-temperature specimen, the blue light source is used to illuminate the specimen, and the optical bandpass filter is placed in front of the camera to allow the blue light passing. In order to verify the DIC method, the strain measurement on a specimen with single skew hole is performed. The relative error in high temperature of the maximum strain between the measurement results and the numerical simulation results given by the finite element method (FEM) is 12%. The strain concentration factor of the single skew hole is measured as 1.83. Finally, the developed method is applied to the strain measurement of the structure with multiple film cooling holes in 870°C. The X-shape strain distribution can be observed at the hole with maximum stress, which suggests that the strain field of multiple holes has coupling effect. In addition, the strain concentration factor of multiple film cooling holes increases to 2.34. [ABSTRACT FROM AUTHOR]

Denitrification in river sediments is the hotspot of nitrogen removal and nosZ I gene is essential for reducing nitrous oxide (N 2 O) emissions. However, few studies tried to link nosZ I communities with variations of denitrification rates in sediments along the high-elevation rivers. Here, we investigated the spatial variation of potential denitrification rates of sediments along a section (hereafter YJ) of the middle reaches of the Yarlung Zangbo River in the Qinghai-Tibetan Plateau. We also used the real-time quantitative PCR (qPCR) and high-throughput sequencing techniques to evaluate the abundance and composition of nosZ I-containing microbial groups. The influences of physicochemical factors and denitrifier communities on potential denitrification rates were further revealed through structural equation modeling. The obtained results indicated that potential denitrification rates and N 2 O/(N 2 O + N 2) ratio in the sediments along YJ section were greatly different. Moreover, the alpha diversity and composition of nosZ I-containing microbial community in river sediments differed remarkably, mainly driven by the ammonia nitrogen (NH 4 +-N), organic matter (OM) and pH in sediments. The relative abundances of Zoogloeaceae , Oxalobacteraceae , Rhodospirillaceae and Bradyrhizobiaceae significantly differed among five groups (P < 0.05). Structural equation modeling further suggested that nitrogen nutrients directly influenced the potential denitrification rates, while total phosphorus (TP) showed indirect effects on potential denitrification rates through modulating denitrifier abundances and nosZ I community. The abundance and composition of nosZ I community were powerful predictors in regulating denitrification rates and N 2 O/(N 2 O + N 2) ratio. Our findings highlight that the nosZ I-containing microbial groups play a non-negligible role in nitrogen removal and N 2 O mitigation in high-elevation river sediments. • Denitrification rates and nosZ I community spatially varied greatly. • Physicochemical factors and community explained 89.9% of denitrification variation. • Physicochemical properties indirectly control denitrification by altering community. • nosZ I community was a powerful predictor for denitrification and N 2 O emission. [ABSTRACT FROM AUTHOR]

This paper proposes an automatic method based on wavelet analysis to detect multiple oscillations in control loops. Continuous wavelet transform provides a way to represent the signal as a superposition of wavelets. The redundancy of the representation can be exploited to precisely indicate the location of oscillatory behaviors in the time-frequency plane. Oscillatory components are separated by the adaptive design of filter bank. It uncovers all the zero-crossings in the frequency bands which possibly include oscillations to be confirmed by Auto-covariance Function (ACF). The method is applicable to non-stationary and noisy data due to the multi-resolution analysis of orthonormal wavelet bases. This paper ends with demonstrating the effectiveness of the proposed method with benchmark industrial data. [ABSTRACT FROM AUTHOR]

Glue-free fiberboard, as a substitute for traditional fiberboard, does not contain a large amount of synthetic resins, which can avoid harm to human health and environment. However, glue-free fiberboard still has some disadvantages of insufficient mechanical strength and excessive thickness swelling of water absorption. Here, corn straw lignin was co-modified by demethylation/hydrothermal degradation to obtain high hydroxyl content increased by 210.85% compared with raw lignin. The co-modified lignin was then introduced into freezing activated wood fibers to prepare the environment-friendly medium density fiberboard (MDF). The effect of co-modified lignin content on the properties of MDF was investigated. MDF with 3 wt% co-modified lignin exhibited the best comprehensive performance with the modulus of elasticity (MOE) of 5809 MPa, modulus of rupture (MOR) as high as 70 MPa, internal bonding strength (IB) of 2.29 MPa and thickness swelling (TS) as low as 16.65%, completely matching the requirements of the Chinese national standard GB/T 11718-2009 and EU national standard BS EN 622–5–2009. The interaction mechanism of co-modified lignin on the wood fibers was further explored by Fourier infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) and scanning electron microscope (SEM) analysis. The phenolic structures of co-modified lignin could be chemically crosslinked with wood fibers during the hot-pressing process and the large amount of hydroxyl groups provided strong hydrogen bond interactions for the glue-free fiberboard. The glue-free fiberboard enhanced by co-modified lignin with excellent comprehensive performance exhibits a broad application prospect. 1 1 MDF: medium density fiberboard; MOR: modulus of rupture; MOE: modulus of elasticity; IB: internal bonding strength; TS: thickness expansion; DSC: differential scanning calorimetry [Display omitted] • Corn straw lignin was co-modified by demethylation and hydrothermal degradation. • Co-modified lignin with high hydroxyl content enhanced the performance of MDF. • Internal bonding strength of MDF was 2.29 MPa much higher than national standards. • Interaction mechanism of co-modified lignin and wood fiber was analyzed. [ABSTRACT FROM AUTHOR]

Bioelectronic medicine uses electrical stimulation of the nervous system to improve health outcomes throughout the body primarily by regulating immune responses. This concept, however, has yet to be applied systematically to the auditory system. There is growing interest in how cochlear damage and associated neuroinflammation may contribute to hearing loss. In conjunction with recent findings, we propose here a new perspective, which could be applied alongside advancing technologies, to use auditory nerve (AN) stimulation to modulate immune responses in hearing health disorders and following surgeries for auditory implants. In this article we will: (1) review the mechanisms of inflammation in the auditory system in relation to various forms of hearing loss, (2) explore nerve stimulation to reduce inflammation throughout the body and how similar neural-immune circuits likely exist in the auditory system (3) summarize current methods for stimulating the auditory system, particularly the AN, and (4) propose future directions to use bioelectronic medicine to ameliorate harmful immune responses in the inner ear and auditory brainstem to treat refractory conditions. We will illustrate how current knowledge from bioelectronic medicine can be applied to AN stimulation to resolve inflammation associated with implantation and disease. Further, we suggest the necessary steps to get discoveries in this emerging field from bench to bedside. Our vision is a future for AN stimulation that includes additional protocols as well as advances in devices to target and engage neural-immune circuitry for therapeutic benefits., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2023 Seicol, Guo, Garrity and Xie.)