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Microstructure evolution and mechanical properties of large-size AZ31 magnesium alloy block fabricated by wire arc additive manufacturing

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Journal of Magnesium and Alloys 2025年第3期13卷 1187-1202页

作者： Wenzhe Yang Haiou Yang Kuitong Yang Xinghua Wang Chenghui Hu Xin Lin State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072PR China Luoyang Ship Material Research Institute Luoyang 471023PR China

With the urgent demand for lightweight and integrated structural parts in the aerospaceﬁeld,the use of cold metal transfer wire arc additive manufacturing(CMT-WAAM)to form large-size magnesium alloy structural parts has become a research *** this paper,a large AZ31 magnesium alloy multilayer block with a lower porosity was successfully prepared by *** AZ31 block exhibits a fully equiaxed grain morphology,the average grain diameters of the top,middle,and bottom are 16.1μm,12.4μm,and 10.4μm,*** submicron spherical particles measuring 0.09 to 0.4μm are Mg17Al12 phases,irregular particles are Al8Mn5+Mg17Al12 composite phases and large particles measuring 5 to 10μm are Al8Mn5 in AZ31 *** UTS of CMT-WAAM AZ31 block from the bottom of 239.9±5.0 MPa to the top of 237.3±3.1 MPa,and the EL from the bottom of 22.7±0.6%to the top of 30.0±1.1%,exceeding the casting *** the CMT-WAAM processed AZ31 alloy,the pre-existing coarse second phase particles in the AZ31ﬁlaments acted as nucleating agents,and the electromagnetic stirring effect in the WAAM process broke up the dendrites and increased the number density of nucleation sites to improve the rate of nucleation,and the complex thermal conditions in the WAAM process restricted the growth of the grains and the precipitated *** mechanical properties of AZ31 alloy were improved by effectively reﬁning its grain size and precipitated phase size.

关键词： Additive manufacturing AZ31 magnesium alloy Microstructure Mechanical property

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Synergistic effect between nitrogen-doped sites and metal chloride for carbon supported extra-low mercury catalysts in acetylene hydrochlorination

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Chinese Journal of Chemical Engineering 2025年第3期79卷 145-154页

作者： Yiyang Qiu Chong Liu Xueting Meng Yuesen Liu Jiangtao Fan Guojun Lan Ying Li Institute of Industry Catalysis Zhejiang University of TechnologyHangzhou 310014China Fujian Institute of Research on Structure of Matter Chinese Academy of SciencesFuzhou 350002China

Carbon-supported mercury catalysts are extensivelyemployed in calcium carbide-based polyvinyl chloride(PVC)industries,but the usage of mercury-based catalysts can pose an environmental threat due to the release of mercury into the surrounding area during the operation *** this study,a highly active and stable mercury-based catalyst was developed,utilizing the nitrogen atom of the support as the anchor site to enhance the interaction between active sites(HgCl_(2))and the carbon support(N-AC).Thermal loss rate testing and thermogravimetric analysis results demonstrate that,compared to commercial activated carbon,N-doped carbon can effectively increase the heat stability of HgCl_(2).The obtained mercury-based catalysts(HgCl_(2)/N-AC)exhibit significant catalytic performance,achieving 2.5 times the C2H2 conversion of conventional HgCl_(2)/AC *** analysis combined with theoretical calculations reveals that,contrary to the Eley-Rideal(ER)mechanism of HgCl_(2)/AC,the HgCl_(2)/N-AC catalyst follows the Langmuir-Hinshelwood(LH)adsorption *** nitrogen sites and HgCl_(2) on the catalyst enhance the adsorption capabilities of the HCl and C2H2,thereby improving the catalytic *** on the modification of the active center by these solid ligands,the loading amount of HgCl_(2) on the catalyst can be further reduced from the current 6.5%to 3%.Considering the absence of successful industrial applications for mercury-free catalysts,and based on the current annual consumption of commercial mercury chloride catalysts in the PVC industry,the widespread adoption of this technology could annually reduce the usage of chlorine mercury by 500 tons,making a notable contribution to mercury compliance,reduction,and emissions control in *** also serves as a bridge between mercury-free and low-mercury ***,this solid ligand technology can assist in the application research of mercury-free catalysts.

关键词： Acetylene hydrochlorination Activated carbon Catalyst support Mercury catalyst DFT calculation Kinetics

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Deep level defect passivation for printable mesoporous CsSnI_(3) perovskite solar cells with efficiency above 10%

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Journal of Energy Chemistry 2025年第3期102卷 10-17页

作者： Haixuan Yu Zhiguo Zhang Huaxia Ban Xiongjie Li Zhirong Liu Junyi Huang Wanpeng Yang Yan Shen Mingkui Wang Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074HubeiChina Optics Valley Laboratory Wuhan 430074HubeiChina

The lead-free inorganic perovskite CsSnI_(3) is considered as one of the best candidates for emerging ***,CsSnI_(3)-based perovskite solar cells experience a significant drop in performance due to the nonradiative recombination facilitated by ***,we show an electron donor passivation method to regulate deep-level defects for CsSnI_(3) perovskite with electron donor *** observations combined with theoretical simulations verify that the saturation of Tin dangling bonds with pyrrole on the CsSnI_(3) surface via a Lewis acid-base addition reaction can significantly reduce the density of deep-level ***,the printable mesoporous perovskite solar cells with an FTO/compact-TiO_(2)/mesoporous-TiO_(2)/Al_(2)O_(3)/NiO/carbon framework device structure penetrated with CsSnI_(3) achieve a power conversion efficiency of up to 10.11%.To our knowledge,this represents the highest efficiency reported to date for lead-free pero vs kite-based printable mesoporous solar ***,the unencapsulated devices demonstrated remarkable long-term stability,retaining 92%of their initial efficiency even after 2400 h of aging in a nitrogen atmosphere.

关键词： Lead-freeperovskite Dangling bonds Defect Recombination Solar cell

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Remote photoplethysmography based on reflected light angle estimation

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PHYSIOLOGICAL MEASUREMENT 2024年第3期45卷 035005-035005页

作者： Fan, Xuanhe Liu, Fangwu Zhang, Jinjin Gao, Tong Fan, Ziyang Huang, Zhijie Xue, Wei Zhang, Jingjing China Univ Geosci Sch Automat Hubei Key Lab Adv Control & Intelligent Automat Co Wuhan Peoples R China Shanghai Inst Tech Phys Chinese Acad Sci Shanghai Peoples R China

Objective. In previous studies, the factors affecting the accuracy of imaging photoplethysmography (iPPG) heart rate (HR) measurement have been focused on the light intensity, facial reflection angle, and motion artifacts. However, the factor of specularly reflected light has not been studied in detail. We explored the effect of specularly reflected light on the accuracy of HR estimation and proposed an estimation method for the direction of specularly radiated light. Approach. To study the HR measurement accuracy influenced by specularly reflected light, we control the component of specularly reflected light by controlling its angle. A total of 100 videos from four different reflected light angles were collected, and 25 subjects participated in the dataset collection. We extracted angles and illuminations for 71 facial regions, fitting sample points through interpolation, and selecting the angle corresponding to the maximum weight in the fitted curve as the estimated reflected angle. Main results. The experimental results show that higher specularly reflected light compromises HR estimation accuracy under the same value of light intensity. Notably, at a 60 degrees angle, the HR accuracy (ACC) increased by 0.7%, while the signal-to-noise ratio and Pearson correlation coefficient increased by 0.8 dB and 0.035, respectively, compared to 0 degrees. The overall root mean squared error, standard deviation, and mean error of our proposed reflected light angle estimation method on the illumination multi-angle incidence (IMAI) dataset are 1.173 degrees, 0.978 degrees, and 0.773 degrees. The average Pearson value is 0.8 in the PURE rotation dataset. In addition, the average ACC of HR measurements in the PURE dataset is improved by 1.73% in our method compared to the state-of-the-art traditional methods. Significance. Our method has great potential for clinical applications, especially in bright light environments such as during surgery, to improve accuracy and monitor blood

关键词： remote heart rate measurement remote photoplethysmography reflected light uneven illumination angle estimation

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DOPA/PEI surface-modified poly-4-methyl-1-pentene membranes and application in membrane aeration biofilm reactor

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Chinese Journal of Chemical Engineering 2025年第1期77卷 114-122页

作者： Yue Zhou Wenjun Li Hongjun Hu Zhaohui Wang Zhaoliang Cui State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 210009China National Engineering Research Center for Special Separation Membrane Nanjing Tech UniversityNanjing 210009China

The membrane aeration biofilm reactor(MABR)represents an innovative approach to wastewater treatment,integrating gas separation membranes with biofilm process and demonstrating effectiveness in treating wastewater rich in ammonia *** this system,hollow fiber membranes are essential,serving as a substrate for biofilm attachment while facilitating oxygen transfer to microorganisms through aeration,hydrophobic microporous membranes are utilized in MABR *** study focuses on the use of poly-4-methyl-1-pentene(PMP)hollow fiber membranes,which exhibit superior oxygen permeation capabilities compared to traditional hydrophobic microporous *** overcome the challenges posed by the hydrophobic nature and low bubble point of PMP microporous membranes,a hydrophilic modification was conducted using dopamine/poly(ethyleneimine)(DOPA/PEI)co-deposition to enhance microbial adhesion on the membrane *** composite membrane modified with DOPA/PEI exhibited an approximately 20%higher NH_(4)^(+)-N removal efficiency than the unmodified *** findings suggest that the incorporation of DOPA/PEI significantly improves MABR performance,underscoring its potential for further research and development in membrane technology for MABR.

关键词： Membrane aeration biofilm reactor Poly(4-methyl-1-pentene) Hollow fiber membrane Co-deposition modification

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A stepwise approach to enhancing flotation of low-grade zinnwaldite through the cationic/DL-2-octanol/anionic reagent combinations: Behavior and mechanism analysis

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International Journal of Mining Science and Technology 2024年第6期34卷 881-891页

作者： Zhonghua Xue Yali Feng Haoran Li Jinrong Ju Xingquan Du School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China Key Laboratory of Biochemical Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

In order to alleviate the pressure on the supply of lithium resources, this research proposes the use of binary/ternary collectors with high selectivity and collecting ability to enhance the flotation purification of low-grade zinnwaldite ore. The binary collector is a mixture of dodecylamine polyoxyethylene ether and DL-2-octanol. A binary collector is added first, followed by sodium oleate, known as a ternary collector. Under acidic conditions, the recovery of Li2O in the concentrate was increased by 8.26% with the binary collector and 13.70% with the ternary collector, compared to the dodecylamine polyoxyethylene ether. The binary collector enhanced the dispersibility of the single collector, while co-adsorption strengthened the hydrophobic nature of the zinnwaldite surface. Consequently, zinnwaldite particles,after the application of binary collector, displayed inter-particle flocculation and attachment to bubbles within 60×10^(-9)m compared to other particles. Ternary collector exhibited the capacity to lower critical micelle concentration and surface tension, subsequently inducing a denser and thicker hydrophobic layer through electrostatic forces, hydrophobic interactions, and chemical reactions. The objective of this research is to facilitate the recovery of lithium resources from low-grade ores in order to meet the needs of sustainable development.

关键词： Zinnwaldite Molecular dynamics simulation Flotation Ternary collector Extended DLVO theory

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Size-Dependent Analysis of Piezoelectric–Elastic Bilayer Microbeams Based on General Strain Gradient Theory

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Acta Mechanica Solida Sinica 2024年第4期37卷 622-633页

作者： Kanghui Wu Shenjie Zhou Zhenjie Zhang Juanjuan Li School of Mechanical Engineering Shandong UniversityJinan250061China Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of EducationShandong UniversityJinan250061China

The classical piezoelectric theory fails to capture the size-dependent electromechanical coupling behaviors of piezoelectric microstructures due to the lack of material length-scale *** study presents the constitutive relations of a piezoelectric material in terms of irreducible transversely isotropic tensors that include material length-scale *** these relations and the general strain gradient theory,a size-dependent bending model is proposed for a bilayer cantilever microbeam consisting of a transversely isotropic piezoelectric layer and an isotropic elastic *** solutions are provided for bilayer cantilever microbeams subjected to force load and voltage *** proposed model can be simplified to the model incorporating only partial strain gradient *** study examines the effect of strain gradient by comparing the normalized electric potentials and deflections of different *** results show that the proposed model effectively captures size effects in piezoelectric microbeams,whereas simplified models underestimate size effects due to ignoring partial strain gradient effects.

关键词： Size dependency Piezoelectric microbeam Size effect Strain gradient effect

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Synthesis of palladium-rare earth alloy as a high-performance bifunctional catalyst for direct ethanol fuel cells

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Nano research 2024年第11期17卷 9525-9531页

作者： Qingqing Li Chang Sun Xiaolei Sun Zijun Yin Yaping Du Jin-Cheng Liu Feng Luo Tianjin Key Laboratory of Rare Earth Materials and Applications School of Materials Science and Engineering Center for Rare Earth and Inorganic Functional Materials Nankai University Tianjin 300350 China The Experimental High School Attached to Beijing Normal University Beijing 100032 China

Direct ethanol fuel cells (DEFCs) have drawn attention for their simplicity, rapid start-up, high power density and environmental friendliness. Despite these advantages, the widespread application of DEFCs faces challenges, primarily due to the inadequate performance of anode and cathode catalysts. Pd-based materials have shown exceptional catalytic activity for both the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR). Alloying noble metals with rare earth elements has emerged as an effective strategy to further enhance the catalytic activity by modulating the electronic structure. In this study, we synthesized a series of palladium-rare earth (Pd3RE) alloys supported on carbon to serve as bifunctional catalysts that efficiently promote both ORR and EOR. Compared to Pd/C, the Pd3Tb/C catalyst exhibits 3.1-fold and 1.8-fold enhancement in activity for ORR and EOR, respectively. The charge transfer in the Pd3Tb/C results in an electron-rich Pd component, thereby weakening the binding energy with oxygen species and facilitating the two reactions.

关键词： rare earth alloy oxygen reduction reaction ethanol oxidation reaction direct ethanol fuel cells bifunctional electrocatalyst charge transfer

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Risk Assessment for Hybrid AC/DC Systems Based on Transient Energy Function

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1654-1663页

作者： Peng Sun Yun Teng Mingli Zhang Zhe Chen Shenyang University of Technology Shenyang 110870China Liaoning Electric Power Co.Ltd.Economic Research Institute Shenyang 110000China Department of Energy Technology Aalborg UniversityAalborgDK DK 9220

In order to accurately assess the risk of the hybrid AC/DC network under fault,a risk assessment method for the hybrid AC/DC system based on the transient energy function is ***,based on the energy transfer relationship of the hybrid AC/DC power system,the transient energy function model of the hybrid AC/DC system is *** on the operating data of the power grid,the energy function is used as an efficiency variable,and the efficiency variable is integrated into the prior risk probability calculation of nodes in the network,and a Bayesian network-based risk assessment model of hybrid AC/DC system is *** the dynamic update model of network cascading failures,the clique tree propagation algorithm is used to dynamically calculate the posterior risk probability of the node to realize the dynamic assessment of the network ***,the improved IEEE-39 node hybrid AC/DC system is used as an example for *** results show that the proposed model can not only effectively evaluate the overall safety of the network,but also has feasibility in predicting faults,which can provide a theoretical basis for the stability control of the hybrid AC/DC system.

关键词： Cascading failure energy function hybrid AC-DC system risk assessment

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Free Probability Theory Based Event Detection for Power Grids Using IoT-enabled Measurements

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Journal of Modern Power Systems and Clean Energy 2024年第5期12卷 1396-1407页

作者： Hongxia Wang Bo Wang Jiaxin Zhang Chengxi Liu Hengrui Ma Hubei Engineering and Technology Research Center for AC/DC IntelligentDistribution Network School of Electrical Engineering and AutomationWuhanUniversityWuhanChina School of Electrical Engi neering and Automation Wuhan UniversityWuhanChina

Taking the advantage of Internet of Things(IoT)enabled measurements,this paper formulates the event detection problem as an information-plus-noise model,and detects events in power systems based on free probability theory(FPT).Using big data collected from phasor measurement units(PMUs),we construct the event detection matrix to reflect both spatial and temporal characteristics of power gird *** event detection matrix is further described as an information matrix plus a noise matrix,and the essence of event detection is to extract event information from the event detection *** associating the event detection problem with FPT,the empirical spectral distributions(ESDs)related moments of the sample covariance matrix of the information matrix are computed,to distinguish events from“noises”,including normal fluctuations,background noises,and measurement *** on central limit theory(CLT),the alarm threshold is computed using measurements collected in normal ***,with the aid of sliding window,this paper builds an event detection architecture to reflect power grid state and detect events *** studies with simulated data from Anhui,china,and real PMU data from Guangdong,china,verify the effectiveness of the proposed *** with other data-driven methods,the proposed method is more sensitive and has better adaptability to the normal fluctuations,background noises,and measurement errors in real PMU *** addition,it does not require large number of training samples as needed in the training-testing paradigm.

关键词： Big data event detection empirical spectral distribution(ESD) free probability theory(FPT) information-plus-noise model Internet of Things(IoT) phasor measurement unit(PMU)

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