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Fatigue crack initiation for Al-Zn-Mg alloy welded joint

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Acta Metallurgica Sinica(English Letters) 2012年第3期25卷 235-240页

作者： Liang ZHANG Xuesong LIU Linsen WANG Ping WANG Hongyuan FANG State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin 150001China Welding process Section Dongfang Boiler Group Co. Ltd. Zigong 643001 China

To investigate fatigue crack initiation characteristics of A1-Zn-Mg alloy welded joint, notched specimens were used in fatigue test for the base metal, welding bead and heat affected zone （HAZ）. The fatigue fracture surface near the fatigue crack initiation site was observed by scanning electron microscope （SEM）. The results show that the differences of fatigue crack initiation life among base metal, welding bead and HAZ are not obvious. Inhomogeneity in microstructure and mechanical performance of HAZ influences the fatigue crack initiation life. The ratio of fatigue crack initiation life （Ni） to fatigue failure life （Nf） for the base metal, welding bead and HAZ of A7N01 aluminium alloy welded joint are 26.32%, 40.21% and 60.67%, respectively. Fatigue crack initiation life can be predicted using a uniform model. Observation of fatigue fracture surfaces shows that for the welding bead a fatigue crack initiates from the smooth surface due to the welding process, the blowhole in HAZ causes fatigue crack and the crushed second phase particles play an important role in fatigue crack initiation for the base metal.

关键词： A1-Zn-Mg alloy Welded joint Fatigue crack initiation Life pre- diction

Two-Stage Mathematical Programming Approach for Steelmaking process Scheduling Under Variable Electricity Price

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Journal of Iron and Steel Research International 2013年第7期20卷 1-8页

作者： TAN Yuan-yuan HUANG Ying-lei LIU Shi-xin College of Information Science and Engineering Northeastern University State Key Laboratory of Synthetical Automation for process Industries Enterprise Solution Business group Shanghai Baosight Software Limited Company

The steelmaking process scheduling problem by considering variable electricity price （SMSPVEP） was in- vestigated. A decomposition approach was proposed for the SMSPVEP. At the first stage, mathematical program-ming was utilized to minimize the maximum completion time for each cast without considering variable electricity price. At the second stage, based on obtained relative schedules of all casts, a mathematical model was formulated with an objective of minimizing the energy cost for all casts scheduling problem. The two-stage models were tested on randomly generated instances based on the practical process in a Chinese steelmaking plant. Computational results demonstrate the effectiveness of the proposed approach.

关键词： steelmaking process scheduling variable electricity price mathematical programming

A Constrained Local Neighborhood Approach for Efficient Markov Blanket Discovery in Undirected Independent Graphs

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Computers, Materials & Continua 2024年第8期80卷 2535-2555页

作者： Kun Liu Peiran Li Yu Zhang JiaRen Ming Li Xianyu Wang Cong Li School of Information and Communication Engineering Hainan UniversityHaikou570228China National Key Laboratory of Science and Technology on Space microwave China Academy of Space Technology Xi’anXi’an710100China Strategic Emerging Industries Department CRSC Communication&Information Group Co.Ltd.Beijing100070China Military Representative Bureau of the Army Equipment Department in Xi’an Xi’an710032China

When learning the structure of a Bayesian network,the search space expands significantly as the network size and the number of nodes increase,leading to a noticeable decrease in algorithm *** constraint-based methods typically rely on the results of conditional independence ***,excessive reliance on these test results can lead to a series of problems,including increased computational complexity and inaccurate results,especially when dealing with large-scale networks where performance bottlenecks are particularly *** overcome these challenges,we propose a Markov blanket discovery algorithm based on constrained local neighborhoods for constructing undirected independence *** method uses the Markov blanket discovery algorithm to refine the constraints in the initial search space,sets an appropriate constraint radius,thereby reducing the initial computational cost of the algorithm and effectively narrowing the initial solution ***,the method first determines the local neighborhood space to limit the search range,thereby reducing the number of possible graph structures that need to be *** process not only improves the accuracy of the search space constraints but also significantly reduces the number of conditional independence *** performing conditional independence tests within the local neighborhood of each node,the method avoids comprehensive tests across the entire network,greatly reducing computational *** the same time,the setting of the constraint radius further improves computational efficiency while ensuring *** to other algorithms,this method can quickly and efficiently construct undirected independence graphs while maintaining high *** simulation results show that,this method has significant advantages in obtaining the structure of undirected independence graphs,not only maintaining an accuracy of over 96%but also reducing the number of conditi

关键词： Bayesian network structure learning Markov blanket conditional independence

Pyrite oxidation in column at controlled redox potential of 900 mV with and without bacteria

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Rare Metals 2022年第12期41卷 4279-4288页

作者： He-Yun Sun Qiao-Yi Tan Yan Jia Rong-Bo Shu Shui-Ping Zhong Ren-Man Ruan State Key Laboratory of Biochemical Engineering Institute of Process EngineeringChinese Academy of ScienceBejing 100190China Key Laboratory of Green process and Engineering Institute of Process EngineeringChinese Academy of ScienceBejing 100190China National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology Institute of Process EngineeringChinese Academy of ScienceBeijing 100190China Institute of Multipurpose Utilization of Mineral Resources Chinese Academy of Geological SciencesChengdu 610041China State Key Laboratory of Gold Extraction Zijin Mining Group Co.Ltd.Shanghang 364200China

Comparisons on the bioleaching and sterile oxidation of pyrite were performed at controlled redox potential of 900 mV(***) and different temperatures of 30 and 60℃.For sterile experiments,the redox potential of irrigation solution was controlled by adding hydrogen peroxide solution(15 wt%),while the redox potential of irrigation solution for bioleaching was elevated by flowing through the packed bed in which bacteria were activated and *** rate of pyrite bioleaching is faster than that of sterile oxidation at temperature of 30℃.The reason is that the potential gradient of leaching solution in bioleaching column is much smaller than that in sterile *** redox potentials of irrigation solution and leaching solution are similar for bioleaching;however,the redox potential difference of irrigation solution and leaching solution for sterile oxidation is about 150 *** temperature increases to 60℃ for sterile oxidation,the rate of pyrite leaching is faster than that of bioleaching at temperature of 30℃,even though the redox potential gradient of leaching solution is *** mineralogy analyses of pyrite residue were performed by scanning electron microscopy-energy-dispersive spectroscopy(SEM-EDS),X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) *** results confirm that pyrite oxidation might only occur at specific sites with high surface energy on surface and obeys the "indirect mechanism" whether there are bacteria or *** pyrite oxidation rate is not inhibited by inert sulfur on residue surface at elevated redox *** to the conclusions,the way to accelerate pyrite oxidation is proposed.

关键词： Pyrite column leaching Temperature Controlled redox potential Bacteria

Investigation of CFD Calculation Method of a Centrifugal Pump with Unshrouded Impeller

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 376-384页

作者： WU Dazhuan YANG Shuai XU Binjie LIU Qiaoling WU Peng WANG Leqin Institute of process Equipment Zhejiang University Engineering Research Center of High Pressure process Equipment and Safety of Ministry of Education Zhejiang University

Currently, relatively large errors are found in numerical results in some low-specific-speed centrifugal pumps with unshrouded impeller because the effect of clearances and holes are not accurately modeled. Establishing an accurate analytical model to improve performance prediction accuracy is therefore necessary. In this paper, a three-dimensional numerical simulation is conducted to predict the performance of a low-specific-speed centrifugal pump, and the modeling, numerical scheme, and turbulent selection methods are discussed. The pump performance is tested in a model pump test bench, and flow rate, head, power and efficiency of the pump are obtained. The effect of taking into consideration the back-out vane passage, clearance, and balance holes is analyzed by comparing it with experimental results, and the performance prediction methods are validated by experiments. The analysis results show that the pump performance can be accurately predicted by the improved method. Ignoring the back-out vane passage in the calculation model of unshrouded impeller is found to generate better numerical results. Further, the calculation model with the clearances and balance holes can obviously enhance the numerical accuracy. The application of disconnect interface can reduce meshing difficulty but increase the calculation error at the off-design operating point at the same time. Compared with the standard k-ε, renormalization group k-ε, and Spalart-Allmars models, the Realizable k-ε model demonstrates the fastest convergent speed and the highest precision for the unshrouded impeller flow simulation. The proposed modeling and numerical simulation methods can improve the performance prediction accuracy of the low-specific-speed centrifugal pumps, and the modeling method is especially suitable for the centrifugal pump with unshrouded impeller.

关键词： centrifugal pump unshrouded impeller numerical simulation clearance turbulence model

Comparison and Performance Analysis of Heat Storage Equipment in Solar Heating System

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Journal of Donghua University(English Edition) 2013年第3期30卷 197-201页

作者：穆振英丁玉龙 Beijing Gas group Corporation Ltd. State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of Sciences

Solar heating system is widely used recently. Heat storage equipment is the guarantee for steady performance of solar heating system. A design of latent heat storage exchanger with submerged coil was introduced with the structure, working principle, and the main advantages. This heat exchanger was integrated into solar heating system as the heat storage equipment. Advantage comparison of the designed heat exchanger in solar heating system with hot water tank was carried out. The analysis results show that the latent heat storage exchanger is superior to hot water tank obviously. The heat exchanger performance parameters and variations of these parameters are got：（1） with the increase of phase change material （PCM） volume ratio, heat storage equipment volume ratio decreases; （2） heat storage efficiency has the same varying tendency with outdoor and air temperature; while the bigger PCM volume ratio is, the weaker the effect of outdoor air temperature on heat storage efficiency is; （3） heat storage capacity and heat storage efficiency increase together; when PCM volume ratio is big, heat storage efficiency is high and the system can begin operating effcienfly and quickly; （4） with the increase of heat storage capacity, life cyde operation cost （LCOC） of system increases gradually in high speed; but with the increase of PCM volume ratio, the difference between the two systems LCOCs becomes smaller and smaller; （5） the reasonable range of PCM volume ratio is 0.5 - 0.7. Temperature characteristic analysis shows that, with the filled PCM, heat storage medium temperature presents several segments at different time, under conditions of different heat storage capacity and different PCM state.

关键词： solar heating system latent heat storage exchanger with submerged coil hot water tank comparative analysis temperature characteristic

Stress control of silicon nitride films deposited by plasma enhanced chemical vapor deposition

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Optoelectronics Letters 2016年第4期12卷 285-289页

作者：李东玲冯小飞温志渝尚正国佘引 National Key Laboratory of Fundamental Science of Novel micro/nano Device and System Technology Chongqing University Chongqing 400030 China Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China Chongqing University Chongqing 400030 China No.24 Reaearch Institute of China Electronics Technology group Corporation Chongqing 400060 China

Stress controllable silicon nitride(Si Nx) films deposited by plasma enhanced chemical vapor deposition(PECVD) are reported. Low stress Si Nx films were deposited in both high frequency(HF) mode and dual frequency(HF/LF) mode. By optimizing process parameters, stress free(-0.27 MPa) Si Nx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited Si Nx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit(IC), micro-electro-mechanical systems(MEMS) and bio-MEMS.

关键词： Deposition Deposition rates Integrated circuits MEMS Nitrides Optical properties Plasma CVD Refractive index Silicon nitride Stresses Vapor deposition

Distribution characteristics and removal rate of antibiotics and antibiotic resistance genes in different treatment processes of two drinking water plants

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Frontiers of Environmental Science & Engineering 2024年第9期18卷 143-152页

作者： Jun Wang Mingtao Huang Bolin Li Hassan Ibrahim Mohamed Huanjie Song Gezi Li Ying Yu Han Zhang Weimin Xie School of Resource and Environmental Engineering Wuhan University of TechnologyWuhan 430070China Wuhan Lingang Economic and Technological Development Zone Service Industry Development Investment group Co.Ltd. Wuhan 430040China Civil Engineering Department Faculty of EngineeringAssiut UniversityAssiut 71516Egypt Changjiang Basin Ecology Environment and Monitoring and Scientific Research Center Changjiang Basin Ecology and Environment AdministrationMinistry of Ecological EnvironmentWuhan 430010China

Emerging pollutants,such as antibiotics and antibiotic-resistance genes,are becoming increasingly important sources of safety and health *** water safety,which is closely related to human health,should receive more attention than natural water body ***,minimal research has been performed on the efficacy of existing treatment processes in water treatment plants for the removal of antibiotics and antibiotic resistance *** address this research gap,this study detected and analyzed six main antibiotics and nine antibiotic resistance genes in the treatment processes of two drinking water plants in *** were collected over three months and then detected and analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry and fluorescence *** total concentrations of antibiotics and antibiotic resistance genes in the influent water of the two water plants were characterized as December>March>*** precipitation and filtration processes of the Zou Maling Water Plant and Yu Shidun Water Plant successfully removed the *** ozone-activated carbon process increased the removal rate of most antibiotics to 100%.However,a large amount of antibiotic resistance gene residues remained in the effluents of the two water *** experiments demonstrated that the existing ozone-activated carbon processes could not effectively remove antibiotic resistance *** study provides a reference for the optimization of drinking water treatment processes for antibiotics and antibiotic resistance gene removal.

关键词： Antibiotics Antibiotics resistance genes Water treatment process unit Spatiotemporal distribution Removal efficacy

Occurrence and vertical distribution of aluminum and rare earths in weathered crust elution-deposited rare earth ore:Effect of soil solution pH and clay minerals

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Journal of Rare Earths 2024年第7期42卷 1394-1402,I0007页

作者： Jiaxin Pan Longsheng Zhao Zheng Li Xiaowei Huang Zongyu Feng Jun Chen National Engineering Research Center for Rare Earth China GRINM Group Co.Ltd.Beijing100088China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing100083China GRIREM Hi–Tech Co. Ltd.Langfang065201China GRIREM Advanced Materials Co. Ltd.Beijing100088China GRIMAT Engineering Institute Co. Ltd.Beijing101407China

Weathered crust elution-deposited rare earth ore is crucial source of medium and heavy rare earths,with in-situ leaching being the most common mining *** high contents of impurity of aluminum in the leach solution are a significant challenge for the subsequent enrichment process of rare earths.A comprehensive understanding of the occurrences and vertical distribution of aluminum and rare earths within typical vertical profiles can provide valuable insights into entire design of the in-situ *** paper improves a five-step sequential extraction method to analyze the occurrence and vertical distribution of rare earths and aluminum in vertical profiles from Chongzuo and *** results demonstrate that soil solution pH is the main factor affecting the vertical distribution of ionexchangeable rare *** samples have distinct areas of enrichment for ion-exchangeable rare earths or ***-exchangeable rare earths are primary concentrated in the middle and lower parts of the ore layer(4-13 m in Chongzuo,14-22 m in Longyan),while the ion-exchangeable aluminum is mainly enriched in the upper part of the ore layer(1-5 m in Chongzuo,and 2-14 m in Longyan).The vertical distribution of inorganic hydroxy aluminum is likely influenced by the micromorphology and particle size of the clay *** inorganic hydroxy aluminum concentration in Chongzuo samples decreases continuously from 415.65 to 120.95 mg/kg with increasing sampling depth,whereas the concentration in Longyan samples(110.55-171.27 mg/kg)is almost independence with sampling *** results provide direct guidance for the entire design of the injection well depth and the leaching parameters,thereby inhibiting the leaching of impurity of aluminum and lower the consumption of leaching agent.

关键词： Weathered crust elution-deposited rare earth ore Sequential extraction Occurrence Aluminum Rare earth elements