摘要：
Fatigue performances of critical structures are strongly affected by the microstructural (e.g. grain, defect, inclusion, etc.) size effect, and it is thus important to quantify their detrimental effect. In this work, a numerical procedure is constructed to quantify the influence of microstructure on the mechanical and fatigue behaviors of Ni-based superalloy GH4169. Specifically, by combining sub modelling approach with crystal plasticity constitutive model, a dual-scale modelling approach is developed for studying grain-level mechanical behavior of Ni-based superalloy GH4169 notched components. In addition, the dislocation-based Tanaka-Mura-Wu model is applied for fatigue crack initiation life prediction. The Paris law is then utilized for fatigue crack propagation analysis based on the simulated short crack. To study the microstructural size effect on fatigue crack initiation and propagation behaviors, sub-models containing various grain orientation, grain size, defect size/shape are built and analysed. Finally, a series of fatigue tests on notched specimens of Ni-based superalloy GH4169 were carried out for method validation. Results indicate that the established dual-scale modelling approach and fatigue life prediction framework yields good agreement with experimental results.
摘要：
Abstract Reducing the burden of social security contributions for firms, unleashing their vitality, and enhancing their total factor productivity (TFP) are crucial measures in China's pursuit of sustainable and high‐value‐added growth. This article utilizes three reductions in the corporate pension insurance contribution ratio in China as a quasi‐natural experiment to construct a treatment intensity DID (Difference‐in‐Differences) model. By utilizing data from listed companies between 2013 and 2020, this study empirically examines the impact of reducing the pension insurance contribution ratio on firms’ TFP while identifying the underlying mechanisms. The findings of the study are as follows: First, the policy exhibits a significant positive effect on corporate TFP in China. Second, this policy's contribution primarily stems from stimulating firms to increase their employment of highly skilled labour, elevating wages for ordinary employees, and enhancing firm investment efficiency. Lastly, the analysis of heterogeneity demonstrates that the policy's positive effect is more pronounced among non‐state‐owned enterprises, small and medium‐sized enterprises, and labour‐intensive enterprises. This study provides empirical evidence for evaluating the contribution reduction policy and serves as a policy reference for endeavours to deepen the reform of the pension insurance system and enhance pension insurance fund budget management.
期刊：
Biomedical Signal Processing and Control,2024年92:106022 ISSN：1746-8094
通讯作者：
Guang Li
作者机构：
[Shuo Zhao; Han Gao; Xuran Li; Huiyan Li; You Wang; Ruifen Hu; Guang Li] State Key Laboratory of Industrial Control Technology, Institute of Cyber-Systems and Control, Zhejiang University, Hangzhou, 310027, China;[Jin Zhang; Wei Yao] School of Computer and Communication Engineering, Changsha University of Science and Technology, Changsha, 410114, China
通讯机构：
[Guang Li] S;State Key Laboratory of Industrial Control Technology, Institute of Cyber-Systems and Control, Zhejiang University, Hangzhou, 310027, China
摘要：
Electroencephalography (EEG) is commonly used for measuring brain activity information due to its high temporal resolution. However, it severely suffers from noises produced by non-brain sources, called EEG artifacts. Ocular, muscle, and power line artifacts are the most common ones. In this paper, a novel two-stage automatic artifact removal method is proposed to handle different artifacts under miscellaneous EEG applications. Empirical wavelet transform (EWT), canonical correlation analysis (CCA), and an outlier detection algorithm, isolation forest constitute the pipeline. In the first stage, EEG data are decomposed by CCA and preliminary purified by isolation forest. In the second stage, a further decomposition of the EEG data is conducted using EWT and CCA, followed by removal of irrelevant components using isolation forest. We thoroughly evaluate the qualitative and quantitative performance of the proposed method on multiple datasets. Experiment results show that the proposed method can effectively remove artifacts under complex conditions and different signal-to-noise ratios. Ablation studies and comparison results demonstrate the significance of the two-stage combination, which outperforms single-stage methods and state-of-the-art methods. This paper explores the potential for a fully data-driven and adaptive way for robust artifact removal in various EEG applications.
期刊：
Journal of Hazardous Materials,2024年469:134022 ISSN：0304-3894
通讯作者：
Xue, Wenjing
作者机构：
[Lin, Weilong; Liu, Hongdou; Wen, Siqi; He, Qi; Shi, Xiaoyu; Xu, Yiqun; Guo, Jiaming] College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225009, PR China;[Gao, Yang] School of Hydraulic and Environmental Engineering, Changsha University of Science & Technology, Changsha 410114, PR China;[Wang, Rongzhong] School of Resource & Environment and Safety Engineering, University of South China, Hengyang 421001, PR China;[Xue, Wenjing] College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225009, PR China. Electronic address: xuewenjing@yzu.edu.cn
通讯机构：
[Xue, Wenjing] C;College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225009, PR China. Electronic address:
关键词：
Bacterial community;Cadmium;Precursor;Sediment;Sulfidized nanoscale zero-valent iron
摘要：
Sulfidized nanoscale zero-valent iron (S-nZVI) showed excellent removal capacity for cadmium (Cd) in aqueous phase. However, the remediation effects of S-nZVI on Cd-contaminated sediment and its interactions with microorganisms in relation to Cd fate remain unclear. The complexity of the external environment posed a challenge for Cd remediation. This study synthesized S-nZVI with different S and Fe precursors to investigate the effect of precursors and applied the optimal material to immobilize Cd in sediments. Characterization analysis revealed that the precursor affected the morphology, Fe(0) crystallinity, and the degree of oxidation of the material. Incubation experiments demonstrated that the immobilization efficiency of Cd using S-nZVI(Fe)(3+)(+S)(2-) (S/Fe = 0.14) reached the peak value of 99.54%. 1% and 5% dosages of S-nZVI significantly reduced Cd concentration in the overlying water, DTPA-extractable Cd content, and exchangeable (EX) Cd speciation (P<0.05). Cd leaching in sediment and total iron in the overlying water remained at low levels during 90 d of incubation. Notably, each treatment maintained a high Cd immobilization efficiency under different pH, water/sediment ratio, organic acid, and coexisting ion conditions. Sediment physicochemical properties, functional bacteria, and a range of adsorption, complexation and precipitation of CdS effects dominated Cd immobilization.
作者机构：
[Li Xu; Cuiping Yi] School of Food Science and Bioengineering, Changsha University of Science and Technology, Changsha, 410114, China;[Tao Wang; Ren Wang] Key Laboratory of Carbohydrate Chemistry and Biotechnology, National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangsu Provincial Research Centre for Bioactive Product Processing Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China;[Yang Shan] Hunan Agricultural Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, China
通讯机构：
[Cuiping Yi] S;School of Food Science and Bioengineering, Changsha University of Science and Technology, Changsha, 410114, China
摘要：
Retrogradation of fresh rice noodles (FRNs) is detrimental to the customers’ acceptance of these rice products. In this study, combined experimental analysis and molecular dynamics simulation were used to explore the mechanism underlying soybean protein isolate (SPI, 0–12%) inhibiting the retrogradation of FRNs. The FRNs showed fast retrogradation and hardening at the 1st day, whereas the aging rate was slowed down in the presence of SPI during the 5-day storage. This was due to that SPI increased the water-holding capacity and buffered the acidity of the system. Differential scanning calorimetry showed that SPI prevented the formation of ordered starch structures during retrogradation. From the results of molecular dynamics simulation, it was found that 7S of SPI could reduce the deformation degree of starch to a lower extent than 11S in the gelatinization process at 95 °C. However, 11S elicited stronger non-covalent interactions with starch than 7S during retrogradation at 4 °C, thus stabilizing starch structures and inhibiting retrogradation of FRNs. Our study illustrated a facile approach to inhibit the retrogradation of FRNs, which would properly broaden the application scenarios of traditional products with enhanced shelf life and taste attributes.
作者机构：
[Jiao, Zengkai; Deng, Zejun; Gang, Yuan; Zhou, Kechao; Deng, ZJ; Wei, Qiuping; Wang, Xiang; Ma, Li; Wei, QP; Li, Haichao] Cent South Univ, Sch Mat Sci & Engn, State Key Lab Powder Met, Changsha 410083, Peoples R China.;[Zhang, Long] Changsha Univ Sci & Technol, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.;[Wang, Yijia] Cent South Univ, Adv Res Ctr, Changsha 410083, Peoples R China.
通讯机构：
[Zhou, KC; Deng, ZJ; Wei, QP ] C;Cent South Univ, Sch Mat Sci & Engn, State Key Lab Powder Met, Changsha 410083, Peoples R China.
关键词：
Cu-matrix composite;Diamond skeleton;Gas pressure infiltration;High-efficiency heat transfer
摘要：
The weak interfacial bonding strength between diamond and copper intrinsically restricts the enhancement of the thermal conductivity of diamond particles/copper composites (abbreviated as DP/Cu). This work first proposed the diamond skeleton (DS) as the reinforcement element rather than dispersed diamond particles. The tungsten (W) transition layer (c.a. similar to 300 nm thick) having adequate thermal expansion coefficient was sputtered onto the surface of DS via vacuum evaporation technology, aiming to improve the wettability between diamond and copper and accordingly increase the thermal conductivity of DS/copper composites extruded by gas pressure infiltration technique. The experimental results show that the coated W layer can effectively improve the wettability of the diamond surface and reduce the wettability angle from 108.6 degrees to 13.2 degrees. Raman and XRD spectra show that the W layer can, to a great extent, prevent the graphitization of the diamond surface. SEM and EDX evidence a continuous heat transfer path of DS inside the composites. The thermal conductivity of the DS/Cu composite with low diamond loading of 18.4 vol% reaches 575 W/mK, 43.3% higher than that of pure Cu. Finite element simulations show that DS exhibits excellent heat transfer characteristics, agreeing well with the thermal conductivity simulation results.
关键词：
White layer;Dark layer;Grinding processes;Forming mechanism;Microstructures;Hardness
摘要：
To establish a systematic cognition of formation mechanisms of affected layers in hardened AISI 52100 steel, the experiments were conducted to measure and characterize the microstructure and properties of the affected layers subject to a varying grinding depth and thermal and mechanical effects at different-levels. It is found that the affected layers can be formed mechanically or thermally depending on whether the mechanically-induced effect predominates the thermally-induced effect, and the 25 mu m is exactly the critical grinding depth of the above two effects. From the novel perspective of thermo-mechanical decoupling, when the grinding depth exceeds 25 mu m, grinding temperature is higher than the nominal austenization temperature (Ac1) of the bulk material, the thermally-induced effect becomes dominate, the thickness of the white layer changes abruptly, and there is an obvious dark layer underneath. When the grinding depth is less than 25 mu m, grinding temperature is lower than Ac1, the mechanically-induced effect becomes dominate, the white layer is extremely thin and no dark layer can be observed. The thermally-induced affected layers are formed mainly by a rapid austenite transformation, accompanied by the fragmentation and dissolution of carbide particles, and the white layer is formed on the ground surface. Meanwhile, the subsurface undergoes tempering subjected to high temperature; this leads to the decomposition of austenite and precipitation of a large amount of cementite. With a continuous dynamic recrystallization, a dark softening layer is formed under the white layer. The mechanical-induced affected layers are formed by fragment and refinement of nano- and micro-structures subject to severe plastic deformation and dynamic recovery.
关键词：
双碳目标;“外语 + X”复合型人才;培养路径Carbon Peaking and Neutrality Goal
摘要：
Abstract: With the proposal and implementation of the carbon peaking and carbon neutrality strategy, a large number of high-quality “Foreign Languages + X” international inter-disciplinary talents are urgently needed for international exchanges and cooperation in the energy and power industries in China. Through the analysis of the scientific connotation of the carbon peaking and carbon neutrality goal, this paper discusses the prominent problems in the cultivating of “Foreign Languages + X” inter-disciplinary talents under the carbon peaking and carbon neutrality goal and explores the effective measures of cultivating “Foreign Languages + X” inter-disciplinary talents in terms of expertise, cross-disciplines, teaching system and college-enterprise cooperation, hoping for cultivating more international language service talents to satisfy the carbon peaking and carbon neutrality goal of energy and electric power.#@#@#摘要: 随着双碳战略的提出与实施，我国能源电力行业的国际交流与合作迫切需要大批高素质“外语 + X”国际化复合型人才。本文通过对双碳目标的科学内涵进行分析，探讨了双碳目标下“外语 + X”复合型人才培养中的突出问题，并从专业知识、学科交叉、教学体制、校企合作等方面探索了“外语 + X”复合型人才培养的有效措施，以期培养出更多满足双碳目标下能源电力国际化语言服务人才。
期刊：
Scripta Materialia,2024年240:115850 ISSN：1359-6462
通讯作者：
Chen, CS;Song, M
作者机构：
[Chen, Chuansheng; Chen, Jiaxuan] Changsha Univ Sci & Technol, Sch Mat Sci & Engn, Changsha 410114, Hunan, Peoples R China.;[Li, Dan; Liu, Chaoqiang; Song, Miao; Zhang, Xiaoyong; Chen, Jiaxuan; Zhou, Kechao; Niu, Pengda] Cent South Univ, Powder Met Res Inst, Changsha 410083, Hunan, Peoples R China.;[Ma, Xiaolong] City Univ Hong Kong, Dept Mat Sci & Engn, Kowloon, Hong Kong 999077, Peoples R China.;[Zhao, Yunqiang] Guangdong Acad Sci, China Ukraine Inst Welding, Guangdong Prov Key Lab Adv Welding Technol, Guangzhou 510650, Peoples R China.
通讯机构：
[Song, M ; Chen, CS ] C;Changsha Univ Sci & Technol, Sch Mat Sci & Engn, Changsha 410114, Hunan, Peoples R China.;Cent South Univ, Powder Met Res Inst, Changsha 410083, Hunan, Peoples R China.
关键词：
Crack;Titanium alloy;Phase transformation;Transmission electron microscopy (TEM)
摘要：
Designing dual-phase titanium (Ti) alloys with exceptional damage tolerance holds profound scientific and engineering significance. A comprehensive understanding of microstructure evolution around cracks under diverse loading conditions is pivotal in advancing this pursuit. Here, tensile and fatigue cracks were formed quasi in-situ in a dual-phase Ti alloy, and the microstructures around the cracks were systematically analyzed and compared using TEM. Our findings reveal that the deflection of tensile cracks is primarily influenced by the hindrance posed by the straight alpha/beta heterointerfaces and is further facilitated by the beta-to-alpha" martensite transformation within the beta matrix. In contrast, fatigue cracks exhibit deflection within the beta matrix, located far from the alpha lamellae. Furthermore, the presence of spindle-shaped short alpha lamellae holds promise for enhancing resistance to fatigue crack nucleation. These results contribute to fundamental comprehension of the crack nucleation and propagation in dual-phase Ti alloys and provide valuable guidance for materials design.
作者：
Wang, Ziwei;Hu, Lin;Wang, Fang;Lin, Miao;Wu, Ning
期刊：
Sustainability,2024年16(5) ISSN：2071-1050
通讯作者：
Hu, L
作者机构：
[Hu, Lin; Wang, Ziwei; Hu, L; Wang, Fang] Changsha Univ Sci & Technol, Sch Automot & Mech Engn, Changsha 410114, Peoples R China.;[Lin, Miao] China Automobile Technol Res Ctr Co Ltd, Tianjin 300300, Peoples R China.;[Wu, Ning] Ruhr Univ, Inst Traff Engn & Management, D-44801 Bochum, Germany.
通讯机构：
[Hu, L ] C;Changsha Univ Sci & Technol, Sch Automot & Mech Engn, Changsha 410114, Peoples R China.
关键词：
traffic safety;injury severity;intersection;random parameters logit model
摘要：
Examining 1192 intersection car and two-wheeled vehicle collision accidents from the China In-Depth Accident Study (CIDAS) database, this study employs population density heat maps for precise assessment of surrounding population densities at accident sites. The K-Medoid clustering algorithm and silhouette coefficient were used to classify accidents into two distinct groups based on population density. Subsequent application of the random parameter logit model revealed key contributing factors to these accidents in varying population densities. The results show notable differences in factors such as collision direction of two-wheeled vehicles, types of accident conflict, road conditions, and traffic flow, depending on the population density. Based on these conclusions, the research can inform differentiated risk prediction for two-wheeled vehicle accidents at intersections and provide insights for intersection design in various population density scenarios.
摘要：
In this study, the axial compressive behaviors of steel reinforced ternary composite geopolymer recycled fireclay brick aggregates concrete columns were investigated. The ternary binder material used in this study was produced by the combination of industrial by-products (i.e., granulated blast furnace slag (GGBS), recycled fireclay brick powder (RFBP), and fly ash (FA)) and alkali-activated solution. A total of 60 square steel reinforced composite columns (with a 200-mm side length and 600-mm height) were tested under axial compression. The tested variables included the mix proportion of ternary composite geopolymer concrete with recycled aggregates containing recycled fireclay brick aggregates (GRA-RFBAC), the recycled coarse aggregate replacement ratios (0%, 30%, 50%, 70%, 100%), the longitudinal reinforcement ratios (1.13%, 2.01%), and the hoop stirrup reinforcement ratios (0.81%, 1.62%). Each group contained three identical samples. The ductility, failure mode, and axial load-bearing capacity of the columns were recorded and analyzed. The experimental results revealed that the damage progression and patterns of steel reinforced GRA-RFBAC columns were similar to those of ordinary Portland cement based recycled concrete columns. The ultimate bearing capacity of steel reinforced GRARFBAC columns decreased with an increasing replacement ratio of recycled coarse aggregate and increased with an increasing reinforcement ratio of longitudinal and hoop stirrups. Meanwhile, the stress-strain model of steel reinforced GRA-RFBAC columns under axial compression was proposed based on the experimental results. The present study suggests an efficient and environmental-friendly compression member.
摘要：
The DOC (diesel oxidation catalyst), DPF (diesel particulate filter), SCR (selective catalytic reduction), and ASC (ammonia slip catalyst) are widely used in diesel exhaust after-treatment systems. The thermal management of after-treatment systems using DOC, DPF, SCR, and ASC were investigated to improve the efficiency of these devices. This paper aims to identify the challenges of this topic and seek novel methods to control the temperature. Insulation methods and catalysts decrease the energy required for thermal management, which improves the efficiency of thermal management. Thermal insulation decreases the heat loss of the exhaust gas, which can reduce the after-treatment light-off time. The DOC light-off time was reduced by 75% under adiabatic conditions. A 400 W microwave can heat the DPF to the soot oxidation temperature of 873 K at a regeneration time of 150 s. An SCR burner can decrease NOx emissions by 93.5%. Electrically heated catalysts can decrease CO, HC, and NOx emissions by 80%, 80%, and 66%, respectively. Phase-change materials can control the SCR temperature with a two-thirds reduction in NOx emissions. Pt-Pd application in the catalyst can decrease the CO light-off temperature to 113 degrees C. Approaches of catalysts can enhance the efficiency of the after-treatment systems and reduce the energy consumption of thermal management.
作者机构：
[Tang, Yu; Huang, Zhi-Yong; Wang, Wei; Huang, Ya-Lan; Liu, Qi; Zhang, Bing-Hao; Ren, Jin-Can; Wang, Xing-Yu; Chen, Bo-Wen] City Univ Hong Kong, Dept Phys, Hong Kong 999077, Peoples R China.;[Lan, Si; Liu, Qi; He, Zhang-Long; He, Hao] City Univ Hong Kong, Shenzhen Res Inst, Shenzhen 518057, Peoples R China.;[He, Hao; He, Zhang-Long] Changsha Univ Sci & Technol, Coll Mat Sci & Engn, Changsha 410114, Peoples R China.
通讯机构：
[Liu, Q ; Liu, Q; He, H ] C;City Univ Hong Kong, Dept Phys, Hong Kong 999077, Peoples R China.;City Univ Hong Kong, Shenzhen Res Inst, Shenzhen 518057, Peoples R China.
关键词：
Lithium-ion batteries;Ni fraction;Extreme fast charging;Structural evolution
摘要：
Lithium-ion batteries (LIBs) with extreme fast charging (XFC) capability are considered an effective way to alleviate range anxiety for electric vehicle (EV) buyers. Owing to the high ionic and electronic conductivity of LiNixCoyMnzO2 (x + y + z = 1, NCM) cathodes, the inevitable Li plating of graphite in NCM | graphite cell is usually identified as a key bottleneck for XFC LIBs. However, the capacity decay mechanism of cathode materials under XFC has not been fully investigated. In this work, three typical NCM cathode materials with different Ni fractions were chosen and their electrochemical performances under XFC associated with structural evolution were investigated. A faster capacity decay of NCMs under XFC conditions is observed, especially for Ni-rich NCMs. In-situ X-ray diffraction (XRD) reveals that the multiple c-axis parameters appear at the high-voltage regions in Ni-rich NCMs, which is probably triggered by the larger obstruction of Li (de)intercalation. Particularly, NCMs with moderate Ni fraction also present a similar trend under XFC conditions. This phenomenon is more detrimental to the structural and morphological stability, resulting in a faster capacity decay than that under low current charging. This work provides new insight into the degradation mechanism of NCMs under XFC conditions, which can promote the development of NCM cathode materials with XFC capability.
摘要：
The welding of steel generates substantial welding residual stress (WRS), which exerts a significant impact on the fatigue life of steel bridges. In this study, a physical model for calculating the fatigue crack growth (FCG) life of welded specimens in the WRS field is established based on the weight function method. Experimental data validates the reliability and precision of the proposed physical model. The impact of WRS on the fatigue life of structural components is scrutinized and analyzed. On this basis, a digital twin (DT) framework driven by a physical-data model is proposed to consider the inherent parameter uncertainty in FCG behavior within the WRS domain. A dynamic Bayesian network (DBN) is used to characterize the evolution characteristics of fatigue crack states over time in the digital space. Particle filter algorithm is used as DBN inference method. The results show that the calculation of the physical model is in good agreement with the experimental values. Neglecting the influence of WRS distribution may lead to an overestimation of fatigue life in welded structures. The DT framework can update uncertain parameters online and realize the accurate prediction of the FCG life in the WRS field.
